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Approximately 90% of diabetic males have varying degrees of testicular dysfunction. The current study investigates the possible beneficial consequences of ranolazine against T1DM-induced testicular dysfunction in rats. Thirty-two male Sprague Dawley rats were assorted into 4 groups; normal, diabetic (single 50 mg/kg STZ, I.P.) and ranolazine (40 and 80 mg/kg, orally). The present investigation revealed that the hypoglycemic impact of ranolazine significantly improved the testicular weight and body weight of the final rats, as well as the concentration of blood testosterone, sperm count, and viability, all of which were associated with STZ-induced testicular dysfunction. Furthermore, as demonstrated by elevated reduced glutathione (GSH) activity and lowered malondialdehyde (MDA) levels, diabetic rats administered ranolazine showed a noteworthy improvement in the oxidant/antioxidant ratio. Furthermore, a substantial rise in beclin-1 concentration was seen in conjunction with a significant decrease in thioredoxin-interacting protein (TXNIP) and interleukin-18 (IL-18) concentrations when ranolazine was administered. Although ranolazine exhibited a reduction in inflammation as seen by lower expression of nuclear factor-κB (NF-κB) and cluster of differentiation (CD68) in the testicles, these biochemical findings were validated by improvements in the morphological and histopathological outcomes of both the pancreatic and testicular tissues. In conclusion, daily oral administration of ranolazine (40 and 80 mg/kg) for 8 weeks could be a promising therapy for T1DM-induced testicular dysfunction through its dose-dependent anti-oxidant and anti-inflammatory effects., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

We studied changes of pulmonary microhemodynamics when modeling pulmonary artery thromboembolism on perfused isolated rabbit lungs after pretreatment with ranolazine and ivabradine. The increase in pulmonary artery pressure, pulmonary vascular resistance, and pre- and postcapillary resistance was less pronounced than in control animals, but was close to that in case of pulmonary thromboembolism after pretreatment with voltage-gated Na + channel blockers lidocaine and ropivacaine. The increase of capillary filtration coefficient inversely correlated with values of capillary hydrostatic pressure. Thus, ranolazine and ivabradine exhibit the properties of voltage-gated Na + channel blockers mainly in smooth muscles of pulmonary arterial vessels and promote the decrease in endothelial permeability., (© 2024. Springer Science+Business Media, LLC, part of Springer Nature.)

Background: Multi-faceted evidence from a range of cancers suggests strongly that de novo expression of voltage-gated sodium channels (VGSCs) plays a significant role in driving cancer cell invasiveness. Under hypoxic conditions, common to growing tumours, VGSCs develop a persistent current (I NaP ) which can be blocked selectively by ranolazine., Methods: Several different carcinomas were examined. We used data from a range of experimental approaches relating to cellular invasiveness and metastasis. These were supplemented by survival data mined from cancer patients., Results: In vitro, ranolazine inhibited invasiveness of cancer cells especially under hypoxia. In vivo, ranolazine suppressed the metastatic abilities of breast and prostate cancers and melanoma. These data were supported by a major retrospective epidemiological study on breast, colon and prostate cancer patients. This showed that risk of dying from cancer was reduced by ca.60% among those taking ranolazine, even if this started 4 years after the diagnosis. Ranolazine was also shown to reduce the adverse effects of chemotherapy on heart and brain. Furthermore, its anti-cancer effectiveness could be boosted by co-administration with other drugs., Conclusions: Ranolazine, alone or in combination with appropriate therapies, could be reformulated as a safe anti-metastatic drug offering many potential advantages over current systemic treatment modalities., (© 2024. The Author(s).)

A recent study investigated the correlation between telmisartan (TEL) exposure and Alzheimer's disease (AD) risk among African Americans (AAs) and European Americans. Their findings indicated that moderate-to-high TEL exposure was linked to a decreased incidence of AD among AAs. These results suggest a potential association between TEL and a reduced risk of AD specifically within the AA population. Here, we investigated the effects of TEL, either alone or in combination with ranolazine (Ran) or dapagliflozin (Dapa), on voltage-gated Na + currents ( INa ) in Neuro-2a cells. TEL, primarily used for treating hypertension and cardiovascular disorders, showed a stimulatory effect on INa , while Ran and Dapa reversed this stimulation. In Neuro-2a cells, we demonstrated that with exposure to TEL, the transient ( INa(T) ) and late ( INa(L) ) components of INa were differentially stimulated with effective EC 50 's of 16.9 and 3.1 μM, respectively. The research implies that TEL's impact on INa might be associated with enhanced neuronal excitability. This study highlights the complex interplay between TEL, Ran, and Dapa on INa and their potential implications for AD, emphasizing the need for further investigation to understand the mechanisms involved., (Copyright © 2024 Copyright: © 2024 Journal of Physiological Investigation.)

The vast majority of antianginal drugs decrease heart rate and or blood pressure levels or the inotropic status of the left ventricle to decrease myocardial oxygen consumption (MVO2) and thus anginal symptoms. Ranolazine presents a completely different mechanism of action, which reduces the sodium-dependent calcium overload inhibiting the late sodium current. Current European Society of Cardiology (ESC) guidelines for the management of angina in patients with chronic coronary symptoms recommend the use of several drugs such as ranolazine, b-blockers, calcium channel blockers, long-acting nitrates, ivabradine, nicorandil and trimetazidine for angina relief. However, ranolazine, in addition to symptom relief properties, is an antianginal drug showing favorable effects in decreasing the arrhythmic burden and in ameliorating the glycemic profile of these patients. In this review, we summarize the available data regarding the antianginal and pleiotropic effects of this drug., Competing Interests: Declaration of Competing Interest None, (Copyright © 2023 Southern Society for Clinical Investigation. Published by Elsevier Inc. All rights reserved.)

Background and Objectives : Remote ischemic preconditioning (RIPC) has demonstrated efficacy in protecting against myocardial ischemia-reperfusion injury when applied before percutaneous coronary revascularization. Ranolazine, an anti-ischemic drug, has been utilized to minimize ischemic events in chronic angina patients. However, there is a lack of trials exploring the combined effects of ranolazine pretreatment and RIPC in patients undergoing percutaneous coronary interventions (PCIs). Materials and Methods: The present study is a prospective study which enrolled 150 patients scheduled for nonemergent percutaneous coronary revascularization. Three groups were formed: a control group undergoing only PCIs, an RIPC group with RIPC applied to either upper limb before the PCI (preconditioning group), and a group with RIPC before the PCI along with prior ranolazine treatment for stable angina (ranolazine group). Statistical analyses, including ANOVAs and Kruskal-Wallis tests, were conducted, with the Bonferroni correction for type I errors. A repeated-measures ANOVA assessed the changes in serum enzyme levels (SGOT, LDH, CRP, CPK, CK-MB, troponin I) over the follow-up. Statistical significance was set at p < 0.05. Results : The ranolazine group showed (A) significantly lower troponin I level increases compared to the control group for up to 24 h, (B) significantly lower CPK levels after 4, 10, and 24 h compared to the preconditioning group ( p = 0.020, p = 0.020, and p = 0.019, respectively) and significantly lower CPK levels compared to the control group after 10 h ( p = 0.050), and (C) significantly lower CK-MB levels after 10 h compared to the control group ( p = 0.050). Conclusions : This study suggests that combining RIPC before scheduled coronary procedures with ranolazine pretreatment may be linked to reduced ischemia induction, as evidenced by lower myocardial enzyme levels.

Microglia chronic activation is a hallmark of several neurodegenerative diseases, including the retinal ones, possibly contributing to their etiopathogenesis. However, some microglia sub-populations have anti-inflammatory and neuroprotective functions, thus making arduous deciphering the role of these cells in neurodegeneration. Since it has been proposed that functionally different microglia subsets also rely on different metabolic routes, we hypothesized that modulating microglia metabolism might be a tool to enhance their anti-inflammatory features. This would have a preventive and therapeutic potential in counteracting neurodegenerative diseases. For this purpose, we tested various molecules known to act on cell metabolism, and we revealed the anti-inflammatory effect of the FDA-approved piperazine derivative Ranolazine on microglia cells, while confirming the one of the flavonoids Quercetin and Naringenin, both in vitro and in vivo. We also demonstrated the synergistic anti-inflammatory effect of Quercetin and Idebenone, and the ability of Ranolazine, Quercetin and Naringenin to counteract the neurotoxic effect of LPS-activated microglia on 661W neuronal cells. Overall, these data suggest that using the selected molecules -also in combination therapies- might represent a valuable approach to reduce inflammation and neurodegeneration while avoiding long term side effects of corticosteroids., (© 2023. The Author(s).)

Resistance of melanoma to targeted therapy and immunotherapy is linked to metabolic rewiring. Here, we show that increased fatty acid oxidation (FAO) during prolonged BRAF inhibitor (BRAFi) treatment contributes to acquired therapy resistance in mice. Targeting FAO using the US Food and Drug Administration-approved and European Medicines Agency-approved anti-anginal drug ranolazine (RANO) delays tumour recurrence with acquired BRAFi resistance. Single-cell RNA-sequencing analysis reveals that RANO diminishes the abundance of the therapy-resistant NGFR hi neural crest stem cell subpopulation. Moreover, by rewiring the methionine salvage pathway, RANO enhances melanoma immunogenicity through increased antigen presentation and interferon signalling. Combination of RANO with anti-PD-L1 antibodies strongly improves survival by increasing antitumour immune responses. Altogether, we show that RANO increases the efficacy of targeted melanoma therapy through its effects on FAO and the methionine salvage pathway. Importantly, our study suggests that RANO could sensitize BRAFi-resistant tumours to immunotherapy. Since RANO has very mild side-effects, it might constitute a therapeutic option to improve the two main strategies currently used to treat metastatic melanoma., (© 2023. The Author(s).)

Ranolazine (RN) is a drug used in the treatment of chronic coronary ischemia. Different clinical trials have shown that RN behaves as an anti-diabetic drug by lowering blood glucose and glycosylated hemoglobin (HbA1c) levels. However, RN has not been shown to improve insulin (IN) sensitivity. Our study investigates the possible facilitating effects of RN on the actions of IN in the rabbit aorta. IN induced vasodilation of the abdominal aorta in a concentration-dependent manner, and this dilatory effect was due to the phosphorylation of endothelial nitric oxide synthase (eNOS) and the formation of nitric oxide (NO). On the other hand, IN facilitated the vasodilator effects of acetylcholine but not the vasodilation induced by sodium nitroprusside. RN facilitated all the vasodilatory effects of IN. In addition, IN decreased the vasoconstrictor effects of adrenergic nerve stimulation and exogenous noradrenaline. Both effects were in turn facilitated by RN. The joint effect of RN with IN induced a significant increase in the ratio of p-eNOS/eNOS and pAKT/AKT. In conclusion, RN facilitated the vasodilator effects of IN, both direct and induced, on the adrenergic system. Therefore, RN increases vascular sensitivity to IN, thus decreasing tissue resistance to the hormone, a key mechanism in the development of type II diabetes.

Clinical studies suggest low testosterone levels are associated with cardiac arrhythmias, especially in later life. We investigated whether chronic exposure to low circulating testosterone promoted maladaptive electrical remodeling in ventricular myocytes from aging male mice and determined the role of late inward sodium current ( I Na,L ) in this remodeling. C57BL/6 mice had a gonadectomy (GDX) or sham surgery (1 mo) and were aged to 22-28 mo. Ventricular myocytes were isolated; transmembrane voltage and currents were recorded (37°C). Action potential duration at 70 and 90% repolarization (APD 70 and APD 90 ) was prolonged in GDX compared with sham myocytes (APD 90 , 96.9 ± 3.2 vs. 55.4 ± 2.0 ms; P < 0.001). I Na,L was also larger in GDX than sham (-2.4 ± 0.4 vs. -1.2 ± 0.2 pA/pF; P = 0.002). When cells were exposed to the I Na,L antagonist ranolazine (10 µM), I Na,L declined in GDX cells (-1.9 ± 0.5 vs. -0.4 ± 0.2 pA/pF; P < 0.001) and APD 90 was reduced (96.3 ± 14.8 vs. 49.2 ± 9.4 ms; P = 0.001). GDX cells had more triggered activity (early/delayed afterdepolarizations, EADs/DADs) and spontaneous activity than sham. EADs were inhibited by ranolazine in GDX cells. The selective Na V 1.8 blocker A-803467 (30 nM) also reduced I Na,L , decreased APD and abolished triggered activity in GDX cells. Scn5a (Na V 1.5) and Scn10a (Na V 1.8) mRNA was increased in GDX ventricles, but only Na V 1.8 protein abundance was increased in GDX compared with sham. In vivo studies showed QT prolongation and more arrhythmias in GDX mice. Thus, triggered activity in ventricular myocytes from aging male mice with long-term testosterone deficiency arises from APD prolongation mediated by larger Na V 1.8- and Na V 1.5-associated currents, which may explain the increase in arrhythmias. NEW & NOTEWORTHY Older men with low testosterone levels are at increased risk of developing cardiac arrhythmias. We found aged mice chronically exposed to low testosterone had more arrhythmias and ventricular myocytes had prolonged repolarization, abnormal electrical activity, larger late sodium currents, and increased expression of Na V 1.8 sodium channels. Drugs that inhibit late sodium current or Na V 1.8 channels abolished abnormal electrical activity and shortened repolarization. This suggests the late sodium current may be a novel target to treat arrhythmias in older testosterone-deficient men.

&lt;b&gt;Background and Objective:&lt;/b&gt; Functional Voltage-Gated Sodium Channels (VGSCs) are expressed in metastatic prostate cancer (PCa) cells. A number of &lt;i&gt;in vitro&lt;/i&gt; studies have evaluated the effect of functional VGSC expression on the metastatic cell behavior of PCa cells. This study aimed to evaluate the effect of VGSC inhibition on metastatic cell behavior in PCa cells by meta-analysis. &lt;b&gt;Materials and Methods:&lt;/b&gt; Meta-analysis was performed on data taken from 13 publications that examined the effect of VGSC inhibitors on the metastatic cell behavior of metastatic PCa cells expressing functional VGSCs. The measure of effect was calculated according to the random effects model using mean differences and presented with a forest plot graph. Heterogeneity was checked using the Cochran's Q Test (Chi-square statistic) and the I&lt;sup&gt;2&lt;/sup&gt; test statistic. In order to evaluate the objectivity, the funnels-plot graph was used. &lt;b&gt;Results:&lt;/b&gt; The g value showing the effect size was calculated as 4.49 (95% CI = 5.35-3.62) in the experiments where Tetrodotoxin (TTX) was used, which has a very high specificity for VGSCs but is not licensed for clinical use. In experiments using licensed inhibitors Lamotrigine, Oxcarbazepine, Phenytoin, Ranolazine, Riluzole and Lidocaine, the g value was 1.37 (95 % CI = 2.02-0.71). Suppression of metastatic cell behavior in both subgroups is statistically significant (p<0.00001). &lt;b&gt;Conclusion:&lt;/b&gt; Meta-analysis confirmed that VGSCs are an enhancing factor in the metastasis of PCa cells. The VGSCs appear to be an important target in the diagnosis and development of new treatment options in PCa.

Competing Interests: Competing interests The authors declare no competing interests.

Objective: The aim of this study was to evaluate the effectiveness of ranolazine on hypoxia-inducible factor-1α (HIF-1α) and oxidative stress in H9c2 cardiomyocyte cells., Materials and Methods: We have assessed the effects of increasing concentrations of methotrexate (MTX) and ranolazine on proliferation of H9c2 rat cardiomyocyte cells by MTT assay. Malondialdehyde (MDA) protein oxidation [advanced oxidation protein products (AOPPs)], lipid hydroperoxide (LOOH) and xanthine oxidase (XO) activity as oxidative stress markers and HIF-1α levels increased and total thiol (T-SH), catalase (CAT) activity and total antioxidant capacity (TAC) antioxidant capacity markers decreased in MTX-treated cells compared to control cells., Results: Oxidative stress markers decreased, and antioxidant capacity markers increased in cells treated with ranolazine alone compared to control cells. For all parameters, we showed that the levels of oxidant, antioxidant markers and HIF-1α in cells treated with MTX and ranolazine together reached the level of the control group, and ranolazine reversed the oxidative damage caused by MTX., Conclusions: The cell viability increased the levels of oxidant and prooxidant markers and decreased the levels of antioxidant markers decreased in H9c2 cardiomyocytes induced by oxidative stress. These results suggest that ranolazine may protect the cardiomyocytes from MTX-induced oxidative damage. The effects of ranolazine could result from its antioxidant properties.

Background: Excitation-contraction (E-C) coupling, the interaction of action potential duration (APD) and contractility, plays an essential role in arrhythmogenesis. We aimed to investigate the arrhythmogenic role of E-C coupling in the right ventricular outflow tract (RVOT) in the chloroquine-induced long QT syndrome., Methods: Conventional microelectrodes were used to record electrical and mechanical activity simultaneously under electrical pacing (cycle lengths from 1000-100 ms) in rabbit RVOT tissue preparations before and after chloroquine with and without azithromycin. KB-R7943 (a Na + -Ca 2+ exchanger [NCX] inhibitor), ranolazine (a late sodium current inhibitor), or MgSO 4 were used to assess their pharmacological responses in the chloroquine-induced long QT syndrome., Results: Sequential infusion of chloroquine and chloroquine plus azithromycin triggered ventricular tachycardia (VT) (33.7%) after rapid pacing compared to baseline (6.7%, p = 0.004). There were greater post-pacing increases of the first occurrence of contractility (ΔContractility) in the VT group (VT vs. non-VT: 521.2 ± 50.5% vs. 306.5 ± 26.8%, p < 0.001). There was no difference in the first occurrence of action potential at 90% repolarization (ΔAPD 90 ) (VT vs. non-VT: 49.7 ± 7.4 ms vs. 51.8 ± 13.1 ms, p = 0.914). Pacing-induced VT could be suppressed to baseline levels by KB-R7943 or MgSO 4 . Ranolazine did not suppress pacing-induced VT in chloroquine-treated RVOT. ΔContractility was reduced by KB-R7943 and MgSO 4 , but not by ranolazine., Conclusion: ΔContractility (but not ΔAPD) played a crucial role in the genesis of pacing-induced VT in the long QT tissue model, which can be modulated by NCX (but not late sodium current) inhibition or MgSO 4 ., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Objectives: We assessed the efficacy and safety of ranolazine in real-world patients with hypertrophic cardiomyopathy (HCM)., Background: Ranolazine is an anti-anginal drug that inhibits the late phase of the inward sodium current. In a small prospective trial, ranolazine reduced the arrhythmic burden and improved biomarker profile in HCM patients. However, systematic reports reflecting real-world use in this setting are lacking., Methods: Changes in clinical and instrumental features, symptoms and arrhythmic burden were evaluated in 119 patients with HCM before and during treatment with ranolazine at a national referral centre for HCM., Results: Patients were treated with ranolazine for 2 [1-4] years; 83 (70%) achieved a dosage ≥1000 mg per day. Treatment interruption was necessary in 24 patients (20%) due to side effects (n = 10, 8%) or disopyramide initiation (n = 8, 7%). Seventy patients (59%) were treated with ranolazine for relief of angina. Among them, 51 (73%) had total symptomatic relief and 47 patients (67%) showed ≥2 Canadian Cardiovascular society (CCS) angina grade improvement. Sixteen patients (13%) were treated for recurrent ventricular arrhythmias, including 4 with a clear ischemic trigger, who experienced no further arrhythmic episodes while on ranolazine. Finally, 33 patients (28%) were treated for heart failure associated with severe diastolic dysfunction: no symptomatic benefit could be observed in this group., Conclusion: Ranolazine was safe and well tolerated in patients with HCM. The use of ranolazine may be considered in patients with HCM and microvascular angina., Competing Interests: Declaration of Competing Interest Prof. Olivotto is in the advisory board and had research grant from BMS-Myokardia, Cytokinetics, Boston Scientific, Sanofi Genzyme, Shire Takeda, Amicus, Menarini International, Bayer, Tenaya., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Recent studies suggest a pathogenetic association between metabolic disturbances, including type 2 diabetes (T2DM), and cognitive decline and indicate that T2DM may represent a risk factor for Alzheimer's disease (AD). There are a number of experimental studies presenting evidence that ranolazine, an antianginal drug, acts as a neuroprotective drug. The aim of the present study was to evaluate the effects of ranolazine on hippocampal neurodegeneration and astrocytes activation in a T2DM rat model. Diabetes was induced by a high fat diet (HFD) and streptozotocin (STZ) injection. Animals were divided into the following groups: HFD/STZ + Ranolazine, HFD/STZ + Metformin, HFD/STZ + Vehicle, NCD + Vehicle, NCD + Ranolazine and NCD + Metformin. The presence of neurodegeneration was evaluated in the hippocampal cornus ammonis 1 (CA1) region by cresyl violet staining histological methods, while astrocyte activation was assessed by western blot analysis. Staining with cresyl violet highlighted a decrease in neuronal density and cell volume in the hippocampal CA1 area in diabetic HFD/STZ + Vehicle rats, while ranolazine and metformin both improved T2DM-induced neuronal loss and neuronal damage. Moreover, there was an increased expression of GFAP in the HFD/STZ + Vehicle group compared to the treated diabetic groups. In conclusion, in the present study, we obtained additional evidence supporting the potential use of ranolazine to counteract T2DM-associated cognitive decline.

Ranolazine, an antianginal and antiarrhythmic drug blocking slow inactivating persistent sodium currents, is described as a compound with anticonvulsant potential. Since arrhythmia often accompanies seizures, patients suffering from epilepsy are frequently co-treated with antiepileptic and antiarrhythmic drugs. The aim of this study was to evaluate the effect of ranolazine on maximal-electroshock (MES)-induced seizures in mice as well as interactions between ranolazine and classical antiepileptic drugs in this model of epilepsy. Types of pharmacodynamic interactions were established by isobolographic analysis of obtained data. The main findings of the study were that ranolazine behaves like an antiseizure drug in the MES test. Moreover, ranolazine interacted antagonistically with carbamazepine, phenytoin, and phenobarbital in the proportions of 1:3 and 1:1. These interactions occurred pharmacodynamic, since ranolazine did not change the brain levels of antiepileptic drugs measured in the fluorescence polarization immunoassay. Ranolazine and its combinations with carbamazepine, phenytoin, and phenobarbital did not impair motor coordination evaluated in the chimney test. Unfortunately, an attempt to conduct a passive avoidance task (evaluating long-term memory) resulted in ranolazine-induced delayed lethality. In conclusion, ranolazine exhibits clear-cut anticonvulsant properties in the MES test but interacts antagonistically with some antiepileptic drugs. The obtained results need confirmation in clinical studies. The mechanisms of ranolazine-induced toxicity require specific explanation., Competing Interests: The authors declare no conflicts of interest.

Objective: To determine the electrophysiological effects and related mechanisms of late sodium current inhibitors on hearts with short QT intervals. Methods: The electrophysiological study was performed on isolated Langendorff perfused rabbit hearts. A total of 80 New Zealand White rabbits were used and 34 hearts without drug treatment were defined as control group A, these hearts were then treated with I KATP opener pinacidil, defined as pinacidil group A. Then, 27 hearts from pinacidil group A were selected to receive combined perfusion with sodium channel inhibitors or quinidine, a traditional drug used to treat short QT syndrome, including ranolazine combined group ( n =9), mexiletine combined group ( n =9), and quinidine combined group ( n =9). Nineteen out of the remaining 46 New Zealand rabbits were selected as control group B (no drug treatments, n =19), and then treated with pinacidil, defined as pinacidil group B ( n =19). The remaining 27 rabbits were treated with sodium inhibitors or quinidine alone, including ranolazine alone group ( n =9), mexiletine alone group ( n =9), and quinidine alone group ( n =9). Electrocardiogram (ECG) physiological parameters of control group A and pinacidil group A were collected. In control group B and pinacidil group B, programmed electrical stimulation was used to induce ventricular arrhythmias and ECG was collected. ECG physiological parameters and ventricular arrhythmia status of various groups were analyzed. The concentrations of pinacidil, ranolazine, mexiletine and quinidine used in this study were 30, 10, 30 and 1 μmol/L, respectively. Results: Compared with control group A, the QT interval, 90% of the repolarization in epicardial and endocardial monophasic action potential duration (MAPD 90 -Epi, MAPD 90 -Endo) was shortened, the transmural dispersion of repolarization (TDR) was increased, and the effective refractor period (ERP) and post-repolarization refractoriness (PRR) were reduced in pinacidil group A (all P <0.05). Compared with the pinacidil group A, MAPD 90 -Epi, MAPD 90 -Endo, QT interval changes were reversed in quinidine combined group and mexiletine combined group (all P <0.05), but not in ranolazine combined group. All these three drugs reversed the pinacidil-induced increases of TDR and the decreases of ERP and PRR. The induced ventricular arrhythmia rate was 0 in control group B, and increased to 10/19 (χ 2 =13.6, P <0.05) in pinacidil group B during programmed electrical stimulation. Compared with the pinacidil group B, incidences of ventricular arrhythmia decreased to 11% (1/9), 11% (1/9) and 0 (0/9) (χ 2 =4.5, 4.5, 7.4, P <0.05) respectively in ranolazine group, mexiletine group and quinidine group. Conclusions: Inhibition of late sodium current does not increase but even decreases the risk of malignant arrhythmia in hearts with a shortened QT interval. The antiarrhythmic mechanism might be associated with the reversal of the increase of TDR and the decrease of refractoriness (including both ERP and PRR) of hearts with shortened QT interval.

Aims: Hypothyroidism is associated with an increased risk of cardiovascular disease and enhanced susceptibility to arrhythmias. In our investigation, we evaluated the potential involvement of late sodium current (I Na,late ) in cardiac arrhythmias in an experimental murine model of hypothyroidism., Main Methods: Male Swiss mice were treated with methimazole (0.1 % w/vol, during 21 days) to induce experimental hypothyroidism before ECG, action potential (AP) and intracellular Ca 2+ dynamics were evaluated. Susceptibility to arrhythmia was measured in vitro and in vivo., Key Findings: The results revealed that hypothyroid animals presented ECG alterations (e.g. increased QTc) with the presence of spontaneous sustained ventricular tachycardia. These changes were associated with depolarized resting membrane potential in isolated cardiomyocytes and increased AP duration and dispersion at 90 % of the repolarization. Aberrant AP waveforms were related to increased Ca 2+ sparks and out-of-pace Ca 2+ waves. These changes were observed in a scenario of enhanced I Na,late . Interestingly, ranolazine, a clinically used blocker of I Na,late , restored the ECG alterations, reduced Ca 2+ sparks and aberrant waves, decreased the in vitro events and the severity of arrhythmias observed in isolated cardiomyocytes from hypothyroid animals. Using the in vivo dobutamine + caffeine protocol, animals with hypothyroidism developed catecholaminergic bidirectional ventricular tachycardia, but pre-treatment with ranolazine prevented this., Significance: We concluded that animals with hypothyroidism have increased susceptibility to developing arrhythmias and ranolazine, a clinically used blocker of I Na,late , is able to correct the arrhythmic phenotype., Competing Interests: Declaration of competing interest The author declares that there is no conflict of interest., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Cardiac contractility evaluation using human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) has recently attracted much attention as a clinical cardiotoxicity predictive model. Most studies on this were conducted under spontaneous beating conditions and involved video-based analyses. Cardiac contractility is known to be influenced by beating rates; accordingly, beating rate control is recommended to accurately analyze the effects of drugs on cardiac contractility. Therefore, we investigated the relationship between contraction parameters and beating rates of cardiac cell sheet tissues by directly measuring the contraction force and compared the effects of ion channel drugs (mexiletine, ranolazine, and dofetilide) on contraction parameters under spontaneous beating conditions with those under pacing (1 Hz) conditions. To characterize the contraction/relaxation kinetics, we introduced a novel analysis tool, called a "C-V loop," a plot of contraction force versus force-changing rate ("velocity"). When we increased the beating rate, the contraction force, force-changing rate, and relaxation time markedly decreased. The occurrence frequencies of beating arrest and irregular beats at high concentration ranges of mexiletine and ranolazine were more suppressed in paced samples than in spontaneously beating ones. We also found that relaxation time increased by treatment with dofetilide and contraction amplitude decreased in a concentration-dependent manner by mexiletine treatment only in the samples under pacing. These drug responses were consistent with the previous reports using human samples. These results indicated that beating rate control is necessary to stably evaluate the effects of drugs on contractility and that tests under 1-Hz pacing are more relevant to clinical settings., Competing Interests: Declaration of Competing Interest Yuto Hinata, Yuki Kagawa, and Hirotsugu Kubo are employees of Nihon Kohden Corporation. The University of Tokyo received research funding from Nihon Kohden Corporation. Tatsuya Shimizu is a stakeholder in CellSeed Inc. Tokyo Women's Medical University receives research funding from CellSeed Inc. and Nihon Kohden Corporation. Katsuhisa Matsuura and Tatsuya Shimizu are inventors of bioreactor systems., (Copyright © 2022 The Author(s). Published by Elsevier Inc. All rights reserved.)

Ranolazine (Rn) is a drug used to treat persistent chronic coronary ischemia. It has also been shown to have therapeutic benefits on the central nervous system and an anti-diabetic effect by lowering blood glucose levels; however, no effects of Rn on cellular sensitivity to insulin (Ins) have been demonstrated yet. The present study aimed to investigate the permissive effects of Rn on the actions of Ins in astrocytes in primary culture. Ins (10 -8 M), Rn (10 -6 M), and Ins + Rn (10 -8 M and 10 -6 M, respectively) were added to astrocytes for 24 h. In comparison to control cells, Rn and/or Ins caused modifications in cell viability and proliferation. Rn increased protein expression of Cu/Zn-SOD and the pro-inflammatory protein COX-2 was upregulated by Ins. On the contrary, no significant changes were found in the protein expression of NF-κB and IκB. The presence of Rn produced an increase in p-ERK protein and a significant decrease in COX-2 protein expression. Furthermore, Rn significantly increased the effects of Ins on the expression of p-AKT, p-eNOS, p-ERK, Mn-SOD, and PPAR-γ. In addition, Rn + Ins produced a significant decrease in COX-2 expression. In conclusion, Rn facilitated the effects of insulin on the p-AKT, p-eNOS, p-ERK, Mn-SOD, and PPAR-γ signaling pathways, as well as on the anti-inflammatory and antioxidant effects of the hormone.

Doxorubicin (Dox), a powerful chemotherapeutic agent, has been shown to cause cardiotoxicity and neurotoxicity. Ranolazine, a drug that is commonly used to treat patients with chronic angina, has been shown to reduce toxicity from Dox therapy. Therefore, the present study aims to investigate the mechanisms behind the protective effects of ranolazine on the heart and brain in Dox-treatment. Twenty-four male Wistar rats received 6 doses of either 0.9% normal saline (0.9% NSS, i.p., n = 8) or Dox (3 mg/kg, i.p., n = 16). All Dox-treated rats were assigned into 2 groups to receive vehicle (0.9% NSS, orally; n = 8) or ranolazine (305 mg/kg/day, orally; n = 8) for 30 consecutive days. Following the treatments, left ventricular (LV) function and cognition were determined. Animals were euthanized, then the heart and brain were collected for further analysis. Dox induced systemic oxidative stress/inflammation, and cardiac injury evidenced by mitochondrial dysfunction, mitochondrial dynamic imbalance, and apoptosis, resulting in LV dysfunction. Ranolazine significantly improved LV function via attenuating cardiac injury. Dox also caused brain pathologies as indicated by increased brain inflammation, impaired blood-brain barrier integrity, brain mitochondrial dysfunction, microglial dysmorphology, hippocampal dysplasticity, and increased apoptosis, resulting in cognitive decline. Ranolazine exerted neuroprotective effects by suppressing brain pathologies and restoring cognitive function. These findings suggest that ranolazine has a potential role in cardio- and neuro-protection against chemotherapy., (Copyright © 2022 Elsevier Inc. All rights reserved.)

A plethora of ion channels have been shown to be involved systemically in the pathophysiology of cancer and ion channel blockers can produce anti-metastatic effects. However, although ion channels are known to frequently function in concerted action, little is known about possible combined effects of ion channel modulators on metastatic cell behaviour. Here, we investigated functional consequences of pharmacologically modulating ATP-gated potassium (K ATP ) channel and voltage-gated sodium channel (VGSC) activities individually and in combination. Two triple-negative human breast cancer cell lines were used: MDA-MB-231 and MDA-MB-468, the latter mainly for comparison. Most experiments were carried out on hypoxic cells. Electrophysiological effects were studied by whole-cell patch clamp recording. Minoxidil (a K ATP channel opener) and ranolazine (a blocker of the VGSC persistent current) had no effect on cell viability and proliferation, alone or in combination. In contrast, invasion was significantly reduced in a dose-dependent manner by clinical concentrations of minoxidil and ranolazine. Combining the two drugs produced significant additive effects at concentrations as low as 0.625 μM ranolazine and 2.5 μM minoxidil. Electrophysiologically, acute application of minoxidil shifted VGSC steady-state inactivation to more hyperpolarised potentials and slowed recovery from inactivation, consistent with inhibition of VGSC activation. We concluded (i) that clinically relevant doses of minoxidil and ranolazine individually could inhibit cellular invasiveness dose dependently and (ii) that their combination was additionally effective. Accordingly, ranolazine, minoxidil and their combination may be repurposed as novel anti-metastatic agents., (© 2022. The Author(s).)

Changes in Ca2 + influx during proinflammatory stimulation modulates cellular responses, including the subsequent activation of inflammation. Whereas the involvement of Ca 2+ has been widely acknowledged, little is known about the role of Na + . Ranolazine, a piperazine derivative and established antianginal drug, is known to reduce intracellular Na + as well as Ca2 + levels. In stable coronary artery disease patients ( n = 51) we observed reduced levels of high-sensitive C-reactive protein (CRP) 3 mo after the start of ranolazine treatment ( n = 25) as compared to the control group. Furthermore, we found that in 3,808 acute coronary syndrome patients of the MERLIN-TIMI 36 trial, individuals treated with ranolazine (1,934 patients) showed reduced CRP values compared to placebo-treated patients. The antiinflammatory effects of sodium modulation were further confirmed in an atherosclerotic mouse model. LDL -/- mice on a high-fat diet were treated with ranolazine, resulting in a reduced atherosclerotic plaque burden, increased plaque stability, and reduced activation of the immune system. Pharmacological Na + inhibition by ranolazine led to reduced express of adhesion molecules and proinflammatory cytokines and reduced adhesion of leukocytes to activated endothelium both in vitro and in vivo. We demonstrate that functional Na + shuttling is required for a full cellular response to inflammation and that inhibition of Na + influx results in an attenuated inflammatory reaction. In conclusion, we demonstrate that inhibition of Na + -Ca 2+ exchange during inflammation reduces the inflammatory response in human endothelial cells in vitro, in a mouse atherosclerotic disease model, and in human patients.

Drug-induced human ether-à-go-go-related gene (hERG) channel block and QT interval prolongation increase torsade de pointes (TdP) risk. However, some drugs block hERG channels and prolong QT interval with low TdP risk, likely because they block additional inward currents. We investigated the utility of J-T peak interval, a novel biomarker of inward current block and TdP risk, in conscious telemetered guinea pigs. Electrocardiogram parameters were analysed in Hartley guinea pigs orally administered one of eight test compounds (dofetilide, flecainide, nifedipine, quinidine, quinine, ranolazine, sotalol, verapamil) or vehicle alone as controls. Heart rate-corrected QT (QTcX) and J-T peak (J-T peak cX) were calculated to evaluate the relations of QT-RR and J-T peak -RR. Dofetilide and sotalol significantly increased ΔQTcX and ΔJ-T peak cX intervals to similar degrees. Quinidine, quinine and flecainide also increased ΔQTcX and ΔJ-T peak cX intervals, but the degrees of ΔJ-T peak cX interval prolongation were shorter than those of ΔQTcX interval prolongation. Ranolazine showed slight increasing trends in ΔQTcX and ΔJ-T peak cX intervals, but the differences were not significant. Verapamil and nifedipine did not increase the ΔQTcX or ΔJ-T peak cX intervals. Based on the relations of ΔΔJ-T peak cX and ΔΔQTcX intervals, dofetilide, sotalol and quinidine were classified as high risk for TdP, quinine, flecainide and ranolazine were classified as intermediate risk and verapamil and nifedipine were classified as low risk. These results supported the usefulness of J-T peak interval assessment in conscious guinea pigs for predicting drug-induced balanced block of inward currents and TdP risk in early-stage preclinical studies., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Non-alcoholic fatty liver disease (NAFLD) is characterized by the accumulation of excess fat in the liver in the absence of alcohol and increases one's risk for both diabetes and cardiovascular disease (e.g., angina). We have shown that the second-line anti-anginal therapy, ranolazine, mitigates obesity-induced NAFLD, and our aim was to determine whether these actions of ranolazine also extend to NAFLD associated with type 2 diabetes (T2D). Eight-week-old male C57BL/6J mice were fed either a low-fat diet or a high-fat diet for 15 weeks, with a single dose of streptozotocin (STZ; 75 mg/kg) administered in the high-fat diet-fed mice at 4 weeks to induce experimental T2D. Mice were treated with either vehicle control or ranolazine during the final 7 weeks (50 mg/kg once daily). We assessed glycemia via monitoring glucose tolerance, insulin tolerance, and pyruvate tolerance, whereas hepatic steatosis was assessed via quantifying triacylglycerol content. We observed that ranolazine did not improve glycemia in mice with experimental T2D, while also having no impact on hepatic triacylglycerol content. Therefore, the salutary actions of ranolazine against NAFLD may be limited to obese individuals but not those who are obese with T2D.

Phospholamban (PLN) is a key regulator that controls the function of the sarcoplasmic reticulum (SR) and is required for the regulation of cardiac contractile function. Although PLN-deficient mice demonstrated improved cardiac function, PLN loss in humans can result in dilated cardiomyopathy (DCM) or heart failure (HF). The CRISPR-Cas9 technology was used to create a PLN knockout human induced pluripotent stem cell (hiPSC) line in this study. PLN deletion hiPSCs-CMs had enhanced contractility at day 30, but proceeded to a cardiac failure phenotype at day 60, with decreased contractility, mitochondrial damage, increased ROS production, cellular energy metabolism imbalance, and poor Ca 2+ handling. Furthermore, adding ranolazine to PLN knockout hiPSCs-CMs at day 60 can partially restore Ca 2+ handling disorders and cellular energy metabolism, alleviating the PLN knockout phenotype of HF, implying that the disorder of intracellular Ca 2+ transport and the imbalance of cellular energy metabolism are the primary mechanisms for PLN deficiency pathogenesis., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

β-Cyfluthrin, a class II Pyrethroid, is an insecticide used worldwide in agriculture, horticulture (field and protected crops), viticulture, and domestic applications. β-Cyfluthrin may impair the function of biological systems; however, little information is available about its potential cardiotoxic effect. Here, we explored the acute toxicity of β-Cyfluthrin in isolated heart preparations and its cellular basis, using isolated cardiomyocytes. Moreover, β-Cyfluthrin effects on the sodium current, especially late sodium current (INa-L), were investigated using human embryonic kidney cells (HEK-293) cells transiently expressing human NaV1.5 channels. We report that β-Cyfluthrin raised INa-L in a dose-dependent manner. β-Cyfluthrin prolonged the repolarization of the action potential (AP) and triggered oscillations on its duration. Cardiomyocytes contraction and calcium dynamics were disrupted by the pesticide with a marked incidence of non-electronic-stimulated contractions. The antiarrhythmic drug Ranolazine was able to reverse most of the phenotypes observed in isolated cells. Lastly, ventricular premature beats (VPBs) and long QT intervals were found during β-Cyfluthrin exposure, and Ranolazine was able to attenuate them. Overall, we demonstrated that β-Cyfluthrin can cause significant cardiac alterations and Ranolazine ameliorated the phenotype. Understanding the insecticides' impacts upon electromechanical properties of the heart is important for the development of therapeutic approaches to treat cases of pesticides intoxication., (© 2022 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.)

Background: Electrical storm (ES) is a life-threatening emergency in patients at high risk of ventricular tachycardia/ventricular fibrillation (VF), but the pathophysiology and molecular basis are poorly understood., Objective: The purpose of this study was to explore the electrophysiological substrate for experimental ES., Methods: A model was created by inducing chronic complete atrioventricular block in defibrillator-implanted rabbits, which recapitulates QT prolongation, torsades des pointes (TdP), and VF episodes., Results: Optical mapping revealed island-like regions with action potential duration (APD) prolongation in the left ventricle, leading to increased spatial APD dispersion, in rabbits with ES (defined as ≥3 VF episodes/24 h). The maximum APD and its dispersion correlated with the total number of VF episodes in vivo. TdP was initiated by an ectopic beat that failed to enter the island and formed a reentrant wave and perpetuated by rotors whose centers swirled in the periphery of the island. Epinephrine exacerbated the island by prolonging APD and enhancing APD dispersion, which was less evident after late Na + current blockade with 10 μM ranolazine. Nonsustained ventricular tachycardia in a non-ES rabbit heart with homogeneous APD prolongation resulted from multiple foci with an electrocardiographic morphology different from TdP driven by drifting rotors in ES rabbit hearts. The neuronal Na + -channel subunit Na V 1.8 was upregulated in ES rabbit left ventricular tissues and expressed within the myocardium corresponding to the island location in optically mapped ES rabbit hearts. The Na V 1.8 blocker A-803467 (10 mg/kg, intravenously) attenuated QT prolongation and suppressed epinephrine-evoked TdP., Conclusion: A tissue island with enhanced refractoriness contributes to the generation of drifting rotors that underlies ES in this model. Na V 1.8-mediated late Na + current merits further investigation as a contributor to the substrate for ES., (Copyright © 2021 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Ranolazine is a second-line drug for the management of chronic coronary syndromes (CCS). Glucose-lowering and endothelial effects have also been reported with this agent. However, whether ranolazine may improve short-term glycemic variability (GV), strictly related to the prognosis of patients with type 2 diabetes (T2D), is unknown. Thus, we aimed to explore the effects of adding ranolazine to standard anti-ischemic and glucose-lowering therapy on long- and short-term GV as well as on endothelial function and oxidative stress in patients with T2D and CCS., Methods: Patients starting ranolazine ( n = 16) were evaluated for short-term GV, haemoglobin 1Ac (Hb1Ac) levels, endothelial-dependent flow-mediated vasodilation (FMD), and oxidative stress levels at enrolment and after 3-month follow-up. The same measurements were collected from 16 patients with CCS and T2D that did not receive ranolazine, matched for age, gender, and body mass index., Results: A significant decline in Hb1Ac levels was reported after 3-month ranolazine treatment (mean change -0.60%; 2-way ANOVA p = 0.025). Moreover, among patients receiving ranolazine, short-term GV indexes were significantly improved over time compared with baseline ( p = 0.001 for time in range; 2-way ANOVA p = 0.010). Conversely, no significant changes were reported in patients without ranolazine. Finally, greater FMD and lower oxidative stress levels were observed in patients on ranolazine at 3 months., Conclusions: Ranolazine added to standard anti-ischemic and glucose-lowering therapy demonstrated benefit in improving the glycemic status of patients with T2D and CCS. How this improvement contributes to the overall myocardial benefit of ranolazine requires further studies., Competing Interests: The authors declare that they have no conflict of interest related to the content of the manuscript., (Copyright © 2021 Annunziata Nusca et al.)

Dyslipidemia is commonly linked to skeletal muscle dysfunction, accumulation of intramyocellular lipids, and insulin resistance. However, our previous research indicated that dyslipidemia in apolipoprotein E and low-density lipoprotein receptor double knock-out mice (ApoE/LDLR -/-) leads to improvement of exercise capacity. This study aimed to investigate in detail skeletal muscle function and metabolism in these dyslipidemic mice. We found that ApoE/LDLR -/- mice showed an increased grip strength as well as increased troponins, and Mhc2 levels in skeletal muscle. It was accompanied by the increased skeletal muscle mitochondria numbers (judged by increased citrate synthase activity) and elevated total adenine nucleotides pool. We noted increased triglycerides contents in skeletal muscles and increased serum free fatty acids (FFA) levels in ApoE/LDLR -/- mice. Importantly, Ranolazine mediated inhibition of FFA oxidation in ApoE/LDLR -/- mice led to the reduction of exercise capacity and total adenine nucleotides pool. Thus, this study demonstrated that increased capacity for fatty acid oxidation, an adaptive response to dyslipidemia leads to improved cellular energetics that translates to increased skeletal muscle strength and contributes to increased exercise capacity in ApoE/LDLR -/- mice.

Purpose: Previous clinical studies have shown that ranolazine (RAN) added to amiodarone (AMIO) might accelerate the termination of recent-onset atrial fibrillation. This study was undertaken to delineate possible mechanisms that contribute to the enhancement of the antiarrhythmic efficacy of RAN-AMIO coadministration., Methods: Ten rabbits were anesthetized and two monophasic action potential (MAP) catheters were sequentially inserted into the right atrium. One MAP electrode was used to pace and record; the other electrode was used only for recording MAP from an adjacent atrial region. Intraatrial conduction time (IACT), 2:1 intraatrial conduction block (IACB), and atrial post-repolarization refractoriness (aPRR) were consecutively determined by high-rate atrial burst pacing and programmed stimulation, respectively. All parameters were evaluated during baseline and following AMIO (3 mg/kg iv) or AMIO+RAN (2.4 mg/kg iv bolus +0.134 mg/kg/min maintenance infusion)., Results: The IACT remained unchanged post AMIO compared with baseline (37.6 ± 3.8 vs 36.4 ± 2.4 ms), whereas the addition of RAN to AMIO significantly prolonged IACT (50.4 ± 3.6 ms, p < .001). The pacing cycle length producing 2:1 IACB was 101.2 ± 21.7 ms at baseline , 117.5 ± 15 ms after AMIO (p = 0.265), and 150 ± 14 ms after AMIO+RAN (p < .001). Baseline aPRR was longer following AMIO treatment (35 ± 5 vs 50 ± 9 ms, p < .01) but remarkably prolonged with RAN supplementation (105 ± 11 ms, p < .001)., Conclusions: RAN significantly prolonged the propagation time of rapid atrial depolarizations and potentiated the AMIO-induced moderate increases in aPRR. These mechanisms possibly contribute to the earlier termination of atrial fibrillation when RAN is co-administered with AMIO., (© 2020. Springer Science+Business Media, LLC, part of Springer Nature.)

Native myocardial voltage-gated sodium (NaV) channels function in macromolecular complexes comprising a pore-forming (α) subunit and multiple accessory proteins. Here, we investigated the impact of accessory NaVβ1 and NaVβ3 subunits on the functional effects of 2 well-known class Ib antiarrhythmics, lidocaine and ranolazine, on the predominant NaV channel α subunit, NaV1.5, expressed in the mammalian heart. We showed that both drugs stabilized the activated conformation of the voltage sensor of domain-III (DIII-VSD) in NaV1.5. In the presence of NaVβ1, the effect of lidocaine on the DIII-VSD was enhanced, whereas the effect of ranolazine was abolished. Mutating the main class Ib drug-binding site, F1760, affected but did not abolish the modulation of drug block by NaVβ1/β3. Recordings from adult mouse ventricular myocytes demonstrated that loss of Scn1b (NaVβ1) differentially affected the potencies of lidocaine and ranolazine. In vivo experiments revealed distinct ECG responses to i.p. injection of ranolazine or lidocaine in WT and Scn1b-null animals, suggesting that NaVβ1 modulated drug responses at the whole-heart level. In the human heart, we found that SCN1B transcript expression was 3 times higher in the atria than ventricles, differences that could, in combination with inherited or acquired cardiovascular disease, dramatically affect patient response to class Ib antiarrhythmic therapies.

Late sodium current (late INa) inhibition has been proposed to suppress the incidence of arrhythmias generated by pathological states or induced by drugs. However, the role of late INa in the human heart is still poorly understood. We therefore investigated the role of this conductance in arrhythmias using adult primary cardiomyocytes and tissues from donor hearts. Potentiation of late INa with ATX-II (anemonia sulcata toxin II) and E-4031 (selective blocker of the hERG channel) slowed the kinetics of action potential repolarization, impaired Ca 2+ homeostasis, increased contractility, and increased the manifestation of arrhythmia markers. These effects could be reversed by late INa inhibitors, ranolazine and GS-967. We also report that atrial tissues from donor hearts affected by atrial fibrillation exhibit arrhythmia markers in the absence of drug treatment and inhibition of late INa with GS-967 leads to a significant reduction in arrhythmic behaviour. These findings reveal a critical role for the late INa in cardiac arrhythmias and suggest that inhibition of this conductance could provide an effective therapeutic strategy. Finally, this study highlights the utility of human ex-vivo heart models for advancing cardiac translational sciences.

Dynamic changes in motor abilities and motivated behaviors occur during the juvenile and adolescent periods. The striatum is a subcortical nucleus critical to action selection, motor learning, and reward processing. Its tonically active cholinergic interneuron (ChI) is an integral regulator of the synaptic activity of other striatal neurons, as well as afferent axonal projections of midbrain dopamine (DA) neurons; however, little is known about its development. Here, we report that ChI spontaneous activity increases during postnatal development of male and female mice, concomitant with a decreased afterhyperpolarization (AHP). We characterized the postnatal development of four currents that contribute to the spontaneous firing rate of ChIs, including I SK , I A , I h , and I NaP We demonstrated that the developmental increase in I NaP drives increased ChI firing rates during the postnatal period and can be reversed by the I NaP inhibitor, ranolazine. We next addressed whether immature cholinergic signaling may lead to functional differences in DA release during the juvenile period. In the adult striatum, nicotinic acetylcholine receptors (nAChRs) prevent linear summation of DA release in response to trains of high-frequency stimuli. We show that, in contrast, during the second postnatal week, DA release linearly sums with trains of high-frequency stimuli. Consistently, nAChR antagonists exert little effect on dopamine release at postnatal day (P)10, but enhance the summation of evoked DA release in mice older than postnatal day P28. Together, these results reveal that postnatal maturation of ChI activity is due primarily to enhanced I NaP and identify an interaction between developing cholinergic signaling and DA neurotransmission in the juvenile striatum. SIGNIFICANCE STATEMENT Motor skills and motivated behavior develop rapidly in juvenile rodents. Recent work has highlighted processes that contribute to the postnatal maturation of striatal principal neurons during development. The functional development of the striatal cholinergic interneuron (ChI), however, has been unexplored. In this study, we tracked the ontogeny of ChI activity and cellular morphology, as well as the developmental trajectory of specific conductances that contribute to the activity of these cells. We further report a link between cholinergic signaling and dopamine (DA) release, revealing a change in the frequency-dependence of DA release during the early postnatal period that is mediated by cholinergic signaling. This study provides evidence that striatal microcircuits are dynamic during the postnatal period and that they undergo coordinated maturation., (Copyright © 2021 the authors.)

Purpose: Cellular changes occurring in diabetic cardiomyopathy include disturbances of calcium and sodium homeostasis. Voltage-gated sodium channels are responsible for the initiation of cardiac action potentials, and the excitability would create relevance. The effect of ranolazine as a sodium channel blocker on atrium electromechanical parameters is investigated and compared with lidocaine in streptozocin-treated diabetic rats., Methods: After an 8-week induction of diabetes type I, the effect of cumulative concentrations of ranolazine and lidocaine on the electrophysiology of isolated atrium was studied. Ranolazine's effects were evaluated on cardiac sodium current in normal- and high-glucose medium, with whole-cell patch-clamp technique., Results: Ranolazine at therapeutic concentrations had no significant statistical effect on refractory period in normal and diabetic isolated heart. Ranolazine (10 μM) caused a hyperpolarizing shift of V 1/2 for steady-state inactivation in normal media, while it significantly elicited a depolarizing shift in high-glucose media (p < 0.05)., Conclusion: It is concluded that in the isolated rat atrium preparation, ranolazine and lidocaine have no beneficial on diabetic cardiomyopathy. Although refractoriness and contractility were not much different in normal and diabetic atria, there was a definite effect of ranolazine and lidocaine on sodium current in varying concentrations. This may have significance in future therapeutics.

Background: There is still an unmet need for pharmacologic treatment of atrial fibrillation (AF) with few effects on ventricular electrophysiology. Ranolazine is an antiarrhythmic drug reported to have strong atrial selectivity., Objective: The purpose of this study was to investigate the electrophysiological effects of ranolazine in atria with AF-induced electrical remodeling in a model of lone AF in awake goats., Methods: Electrode patches were implanted on the atrial epicardium of 8 Dutch milk goats. Experiments were performed at baseline and after 2 and 14 days of electrically maintained AF. Several electrophysiological parameters and AF episode duration were measured during infusion of vehicle and different doses of ranolazine (target plasma levels 4, 8, and 16 μM, respectively)., Results: The highest dose of ranolazine significantly prolonged atrial effective refractory period and decreased atrial conduction velocity at baseline and after 2 days of AF. After 2 weeks of AF, ranolazine prolonged the p5 and p50 of AF cycle length distribution in a dose-dependent manner but was not effective in restoring sinus rhythm. No adverse ventricular arrhythmic events (eg, premature ventricular beats or signs of hemodynamic instability) were observed during infusion of ranolazine at any point in the study., Conclusion: The lowest investigated dose of ranolazine, which is expected to block both late I Na and atrial peak I Na , had no effect on the investigated electrophysiological parameters. The highest dose affected both atrial and ventricular electrophysiological parameters at different stages of AF-induced remodeling but was not efficacious in cardioverting AF to sinus rhythm in a goat model of lone AF., (Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

This study investigates the role of ranolazine in contrast-associated acute kidney injury (CA-AKI) and potential mechanisms. For in vivo studies, mouse models of CA-AKI and control mice were treated with ranolazine or vehicle. Blood urea nitrogen (BUN) and serum creatinine were detected by spectrophotometry. Anti-T-cell immunoglobulin and mucin domain 1 (TIM 1) and anti-lipocalin 2 antibody (LCN2) were detected by immunofluorescence. Hemodynamic parameters were detected via invasive blood pressure measurement and renal artery color doppler ultrasound, capillary density was measured by CD31 immunofluorescence, vascular permeability assay was performed by Evans blue dye. The expressions of oxidative stress and apoptotic markers were measured and analyzed by immunofluorescence and western blotting. For in vitro studies, intracellular calcium concentration of HUVECs was measured with Fluo 3-AM under confocal microscopy. Results show that compared with control mice, serum BUN, creatinine, TIM 1 and LCN2 levels were elevated in CA-AKI mice, but this effect was alleviated by ranolazine-pretreatment. Safe doses of ranolazine (less than 64 mg/kg) had no significant effect on overall blood pressure, but substantially improved renal perfusion, reduced contrast-induced microcirculation disturbance, improved renal capillary density and attenuated renal vascular permeability in ranolazine-pretreated CA-AKI mice. Mechanistically, ranolazine markedly down-regulated oxidative stress and apoptosis markers compared to CA-AKI mice. Intracellularly, ranolazine attenuated calcium overload in HUVECs. These results indicate that ranolazine alleviates CA-AKI through modulation of calcium independent oxidative stress and apoptosis., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Introduction: A major outcome determinant in patients with precapillary pulmonary hypertension (PH) is right ventricular (RV) function. We studied the effect of ranolazine on RV function over 6 months using cardiovascular magnetic resonance (CMR) imaging in patients with precapillary PH (groups I, III, and IV)., Methods and Results: We enrolled patients with PH and RV dysfunction (CMR imaging ejection fraction [EF] of <45%) in a longitudinal, randomized, double-blinded, placebo controlled, multicenter study of ranolazine treatment. All enrolled patients were on stable PH-specific therapy. Enrolled patients were assessed using CMR imaging, New York Heart Association functional class, N-terminal pro brain natriuretic peptide, 6-minute walk test, and quality of life health outcomes at baseline and repeated at the end of treatment. The primary outcome was change in RVEF after 6 months of treatment. Analysis of covariance was used to analyze the longitudinal changes taking into account baseline values, age, and sex, based on per protocol population. Twenty-two patients were enrolled, and 9 patients completed follow-up CMR imaging after ranolazine treatment and 6 completed placebo treatment. There was significant increase in RVEF at end of treatment compared with baseline in the ranolazine group adjusted for baseline values, age, and sex. There were no statistically significant changes in secondary outcomes such as changes in New York Heart Association functional class, 6-minute walk distance, N-terminal pro brain natriuretic peptide, or quality of life measures. Ranolazine treated patients experienced a higher number of adverse events, but only one was discontinued owing to side effects., Conclusions: Ranolazine may improve RV function in patients with precapillary PH. Larger studies are needed to confirm the beneficial effects of ranolazine., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Lipid catabolism represents an Achilles heel in prostate cancer (PCa) that can be exploited for therapy. CPT1A regulates the entry of fatty acids into the mitochondria for beta-oxidation and its inhibition has been shown to decrease PCa growth. In this study, we examined the pharmacological blockade of lipid oxidation with ranolazine in TRAMPC1 PCa models. Oral administration of ranolazine (100 mg/Kg for 21 days) resulted in decreased tumor CD8 + T-cells Tim3 content, increased macrophages, and decreased blood myeloid immunosuppressive monocytes. Using multispectral staining, drug treatments increased infiltration of CD8 + T-cells and dendritic cells compared to vehicle. Functional studies with spleen cells of drug-treated tumors co-cultured with TRAMPC1 cells showed increased ex vivo T-cell cytotoxic activity, suggesting an anti-tumoral response. Lastly, a decrease in CD4 + and CD8 + T-cells expressing PD1 was observed when exhausted spleen cells were incubated with TRAMPC1 Cpt1a-KD compared to the control cells. These data indicated that genetically blocking the ability of the tumor cells to oxidize lipid can change the activation status of the neighboring T-cells. This study provides new knowledge of the role of lipid catabolism in the intercommunication of tumor and immune cells, which can be extrapolated to other cancers with high CPT1A expression.

Studies have demonstrated that diabetic (db/db) mice have increased susceptibility to myocardial ischemia-reperfusion (IR) injury and ventricular tachyarrhythmias (VA). We aimed to investigate the antiarrhythmic and molecular mechanisms of ranolazine in db/db mouse hearts with acute IR injury. Ranolazine was administered for 1 week before coronary artery ligation. Diabetic db/db and control db/+ mice were divided into ranolazine-given and -nongiven groups. IR model was created by 15-min left coronary artery ligation and 10-min reperfusion. In vivo electrophysiological studies showed that the severity of VA inducibility was higher in db/db mice than control (db/ +) mice. Ranolazine suppressed the VA inducibility and severity. Optical mapping studies in Langendorff-perfused hearts showed that ranolazine significantly shortened action potential duration, Ca i transient duration, Ca i decay time, ameliorated conduction inhomogeneity, and suppressed arrhythmogenic alternans induction. Western blotting studies showed that the expression of pThr 17 -phospholamban, calsequestrin 2 and voltage-gated sodium channel in the IR zone was significantly downregulated in db/db mice, which was ameliorated with ranolazine pretreatment and might play a role in the anti-arrhythmic actions of ranolazine in db/db mouse hearts with IR injury.

Aims: Diabetic cardiomyopathy (DCM) is a common diabetes complication that can cause arrhythmia, heart failure, and even sudden death. Ranolazine is an antianginal agent used to treat chronic stable angina and has been demonstrated as an effective treatment for many cardiovascular diseases. However, the mechanism by which ranolazine alleviates DCM is unclear, motivating this study investigating the effects of ranolazine in DCM., Materials and Methods: DCM rats were treated with one of three doses of ranolazine (10, 30, and 90 mg/kg/day) for 12 weeks. B-cell lymphoma 2 (Bcl-2), Bcl-2 associated X protein (Bax), cysteinyl aspartate specific proteinase-3 (Caspase-3), Notch homolog 1 (NOTCH1), and Neuregulin 1 (NRG1) expression was assayed using western blot and qRT-PCR. Cardiac changes were assayed using echocardiography, CT, HE staining, and Masson's trichrome staining. TUNEL staining and flow cytometry were used to detect cell apoptosis. NOTCH1 inhibitor (DAPT) was used to explore the mechanism of ranolazine., Key Findings: Compared with the DCM group, the ranolazine groups had no obvious weight loss and significantly decreased blood glucose levels. Ranolazine prevented diabetes-caused cardiac injury. Ranolazine also decreased the number of apoptotic cells and altered the expression of apoptosis-related mRNAs and proteins. Ranolazine-induced NOTCH1 activated NRG1 and inhibited the downstream apoptosis-related pathway, while DAPT partially inhibited ranolazine-induced NOTCH1 and NRG1 expression., Significance: To our knowledge, this study is the first to demonstrate that ranolazine protects against DCM-induced apoptosis by activating the NOTCH1/NRG1 signaling pathway. Moreover, our study identified new mechanisms involved in DCM., (Copyright © 2020. Published by Elsevier Inc.)

GS-967 and eleclazine (GS-6615) are novel sodium channel inhibitors exhibiting antiarrhythmic effects in various in vitro and in vivo models. The antiarrhythmic mechanism has been attributed to preferential suppression of late sodium current ( I NaL ). Here, we took advantage of a high throughput automated electrophysiology platform (SyncroPatch 768PE) to investigate the molecular pharmacology of GS-967 and eleclazine on peak sodium current ( I NaP ) recorded from human induced pluripotent stem cell-derived cardiomyocytes. We compared the effects of GS-967 and eleclazine with the antiarrhythmic drug lidocaine, the prototype I NaL inhibitor ranolazine, and the slow inactivation enhancing drug lacosamide. In human induced pluripotent stem cell-derived cardiomyocytes, GS-967 and eleclazine caused a reduction of I NaP in a frequency-dependent manner consistent with use-dependent block (UDB). GS-967 and eleclazine had similar efficacy but evoked more potent UDB of I NaP (IC 50 = 0.07 and 0.6 µM, respectively) than ranolazine (7.8 µM), lidocaine (133.5 µM), and lacosamide (158.5 µM). In addition, GS-967 and eleclazine exerted more potent effects on slow inactivation and recovery from inactivation compared with the other sodium channel blocking drugs we tested. The greater UDB potency of GS-967 and eleclazine was attributed to the higher association rates and moderate unbinding rate of these two compounds with sodium channels. We propose that substantial UDB contributes to the observed antiarrhythmic efficacy of GS-967 and eleclazine. SIGNIFICANCE STATEMENT: We investigated the molecular pharmacology of GS-967 and eleclazine on sodium channels in human induced pluripotent stem cell-derived cardiomyocytes using a high throughput automated electrophysiology platform. Sodium channel inhibition by GS-967 and eleclazine has unique effects, including accelerating the onset of slow inactivation and impairing recovery from inactivation. These effects combined with rapid binding and moderate unbinding kinetics explain potent use-dependent block, which we propose contributes to their observed antiarrhythmic efficacy., (Copyright © 2020 by The Author(s).)

Introduction: Corrected QT (QTc) interval is an essential proarrhythmic risk biomarker, but recent data have identified limitations to its use. The J to T-peak (JTp) interval is an alternative biomarker for evaluating drug-induced proarrhythmic risk. The aim of this study was to evaluate pharmacological effects using spatial magnitude leads and DII electrocardiogram (ECG) leads and common ECG confounders (ie, stress and body temperature changes) on covariate adjusted QT (QTca), covariate adjusted JTp (JTpca), and covariate adjusted T-peak to T-end (Tpeca) intervals., Methods: Beagle dogs were exposed to body hyper- (42 °C) or hypothermic (33 °C) conditions or were administered epinephrine to assess confounding effects on heart rate corrected QTca, JTpca, and Tpeca intervals. Dofetilide (0.1, 0.3, 1.0 mg/kg), ranolazine (100, 140, 200 mg/kg), and verapamil (7, 15, 30, 43, 62.5 mg/kg) were administered to evaluate pharmacological effects., Results: Covariate adjusted QT (slope -12.57 ms/°C) and JTpca (-14.79 ms/°C) were negatively correlated with body temperature but Tpeca was minimally affected. Epinephrine was associated with QTca and JTpca shortening, which could be related to undercorrection in the presence of tachycardia, while minimal effects were observed for Tpeca. There were no significant ECG change following ranolazine administration. Verapamil decreased QTca and JTpca intervals and increased Tpeca, whereas dofetilide increased QTca and JTpca intervals but had inconsistent effects on Tpeca., Conclusion: Results highlight potential confounders on QTc interval, but also on JTpca and Tpeca intervals in nonclinical studies. These potential confounding effects may be relevant to the interpretation of ECG data obtained from nonclinical drug safety studies with Beagle dogs.

Ranolazine, a late sodium current inhibitor, has been demonstrated to be effective on heart failure. 18β-glycyrrhetinic acid (18β-GA) has the similar inhibitory effect on late sodium currents. However, its effect on diastolic function is still unknown. This study aimed to determine whether 18β-GA can improve the diastolic function and to explore the underlying mechanisms. Eighty male Sprague Dawley (SD) rats of Langendorff model were randomly divided into the following groups: group A, normal cardiac perfusion group; group B, ischemia-reperfusion group; group C, ischemia-reperfusion with anemoniasulcata toxin II (ATX-II); group D, ranolazine group; and group E, 18β-GA group with four different concentrations. Furthermore, a pressure-overloaded rat model induced by trans-aortic constriction (TAC) was established. Echocardiography and hemodynamics were used to evaluate diastolic function at 14th day after TAC. Changes of free intracellular calcium (Ca 2+ ) concentration was indirectly detected by laser scanning confocal microscope to confirm the inhibition of late sodium currents. With the intervention of ATX-II on ischemia reperfusion injury group, 5 µmol/L ranolazine, and 5, 10, 20, 40 µmol/L 18β-GA could improve ATX-II-induced cardiac diastolic dysfunction. 630 mg/kg glycyrrhizin tablets could improve cardiac diastolic function in the pressure-overloaded rats. 18β-GA and ranolazine had similar effects on reducing the free calcium in cardiomyocytes. The study demonstrates that 18β-GA and glycyrrhizin could improve diastolic dysfunction induced by ischemia-reperfusion injury in Langendorff-perfused rat hearts and pressure-overloaded rats. The mechanism may be attributed to the inhibition of enhanced late sodium currents.

Objectives: Ranolazine improves vascular function in animal models. We evaluate the effects of ranolazine on vascular function and adrenergic response in human saphenous vein., Methods: Rings from 53 patients undergoing coronary artery bypass grafting were mounted in organ baths. Concentration-response curves to ranolazine were constructed in rings precontracted with phenylephrine, endothelin-1, vasopressin, KCl and the thromboxane A2 analogue U-46619. In rings precontracted with phenylephrine, relaxation to ranolazine was tested in the absence and presence of endothelial factors inhibitors, K+ channel blockers and verapamil. The effects of ranolazine on frequency-response and concentration-response curves to phenylephrine were performed in the absence and presence of endothelial factors inhibitors and K+ channel blockers. Endothelial nitric oxide synthase, α1 adrenergic receptor and large conductance Ca2+-activated K+ channel protein expressions were measured by Western blotting., Results: Ranolazine (10-9-10-4 M) produced a concentration-dependent relaxation only in rings precontracted with phenylephrine that was reduced by endothelial denudation, NG-nitro-l-arginine methyl ester (10-4 M), charybdotoxin (10-7 M) and verapamil (10-6 M). Ranolazine diminished adrenergic contractions induced by electrical field stimulation (2-4 Hz) and phenylephrine (10-9-10-5 M) that were prevented by tetraethylammonium (10-3 M) and charybdotoxin (10-7 M). Ranolazine significantly decreased α1 adrenergic receptor and increased large conductance Ca2+-activated K+ channel protein expression in the saphenous vein., Conclusions: Ranolazine diminishes the adrenergic vasoconstriction, acting as α1 antagonist, and by increasing large conductance Ca2+-activated K+ channel involvement. The relaxant effects of ranolazine are partially mediated by endothelial nitric oxide, large conductance Ca2+-activated K+ channels and the blockade of voltage-dependent Ca2+ channels., (© The Author(s) 2020. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.)

Cardiovascular complications are leading causes of morbidity and mortality in patients with chronic kidney disease (CKD). CKD significantly affects cardiac calcium (Ca 2+ ) regulation, but the underlying mechanisms are not clear. The present study investigated the modulation of Ca 2+ homeostasis in CKD mice. Echocardiography revealed impaired fractional shortening (FS) and stroke volume (SV) in CKD mice. Electrocardiography showed that CKD mice exhibited longer QT interval, corrected QT (QTc) prolongation, faster spontaneous activities, shorter action potential duration (APD) and increased ventricle arrhythmogenesis, and ranolazine (10 µmol/L) blocked these effects. Conventional microelectrodes and the Fluo-3 fluorometric ratio techniques indicated that CKD ventricular cardiomyocytes exhibited higher Ca 2+ decay time, Ca 2+ sparks, and Ca 2+ leakage but lower [Ca 2+ ] i transients and sarcoplasmic reticulum Ca 2+ contents. The CaMKII inhibitor KN93 and ranolazine (RAN; late sodium current inhibitor) reversed the deterioration in Ca 2+ handling. Western blots revealed that CKD ventricles exhibited higher phosphorylated RyR2 and CaMKII and reduced phosphorylated SERCA2 and SERCA2 and the ratio of PLB-Thr17 to PLB. In conclusions, the modulation of CaMKII, PLB and late Na + current in CKD significantly altered cardiac Ca 2+ regulation and electrophysiological characteristics. These findings may apply on future clinical therapies., (© 2020 The Authors. Journal of Cellular and Molecular Medicine published by Foundation for Cellular and Molecular Medicine and John Wiley & Sons Ltd.)

: Type 2 diabetes mellitus (T2DM) is a risk factor for cognitive impairment. Ranolazine, an anti-ischemic drug used in the treatment of angina pectoris, has been shown to possess hypoglycemic properties in pre-clinical and clinical studies. The aim of this study was to evaluate the effects of ranolazine on glucose metabolism and cognitive function in a T2DM model of Wistar rats. Diabetes was induced by a high fat diet (HFD) and streptozotocin (STZ). The control group received a normal caloric diet (NCD) and sodium citrate buffer. Metformin, an effective hypoglycemic drug, was employed as a positive control. Animals were divided into the following groups: HFD/STZ + Ranolazine, HFD/STZ + Metformin, HFD/STZ + Vehicle, NCD + Vehicle, NCD + Ranolazine, and NCD + Metformin. Rats received ranolazine (20 mg/kg), metformin (300 mg/kg), or water, for 8 weeks. At the end of the treatments, all animals underwent to an intraperitoneal glucose tolerance test (IPGTT) and behavioral tests, including passive avoidance, novel object recognition, forced swimming, and elevate plus maze tests. Interleukin-6 plasma levels in the six treatment groups were assessed by Elisa assay. Body mass composition was estimated by nuclear magnetic resonance (NMR). Glucose responsiveness significantly improved in the HFD/STZ + Ranolazine ( p < 0.0001) and HFD/STZ + Metformin ( p = 0.003) groups. There was a moderate effect on blood glucose levels in the NCD + Ranolazine and NCD + Metformin groups. Lean body mass was significantly increased in the HFD/STZ + Ranolazine and HFD/STZ + Metformin animals, compared to HFD/STZ + Vehicle animals. Ranolazine improved learning and long-term memory in HFD/STZ + Ranolazine compared to HFD/STZ + Vehicle ( p < 0.001) and ameliorated the pro-inflammatory profile of diabetic mice. These results support the hypothesis of a protective effect of ranolazine against cognitive decline caused by T2DM., Competing Interests: The Authors declare no conflict of interests.

Fatty acid oxidation (FAO) is a key bioenergetic pathway often dysregulated in diseases. The current knowledge on FAO regulators in mammalian cells is limited and sometimes controversial. Previous FAO analyses involve nonphysiological culture conditions or lack adequate quantification. We herein described a convenient and quantitative assay to monitor dynamic FAO activities of mammalian cells in physiologically relevant settings. The method enabled us to assess various molecular and pharmacological modulators of the FAO pathway in established cell lines, primary cells and mice. Surprisingly, many previously proposed FAO inhibitors such as ranolazine and trimetazidine lacked FAO-interfering activity. In comparison, etomoxir at low micromolar concentrations was sufficient to saturate its target proteins and to block cellular FAO function. Oxfenicine, on the other hand, acted as a partial inhibitor of FAO. As another class of FAO inhibitors that transcriptionally repress FAO genes, antagonists of peroxisome proliferator-activated receptors (PPARs), particularly that of PPARα, significantly decreased cellular FAO activity. Our assay also had sufficient sensitivity to monitor upregulation of FAO in response to environmental glucose depletion and other energy-demanding cues. Altogether this study provided a reliable FAO assay and a clear picture of biological properties of potential FAO modulators in the mammalian system.

We hypothesized that ranolazine-induced adenosine release is responsible for its beneficial effects in ischemic heart disease. Sixteen open-chest anesthetized dogs with noncritical coronary stenosis were studied at rest, during dobutamine stress, and during dobutamine stress with ranolazine. Six additional dogs without stenosis were studied only at rest. Regional myocardial function and perfusion were assessed. Coronary venous blood was drawn. Murine endothelial cells and cardiomyocytes were incubated with ranolazine and adenosine metabolic enzyme inhibitors, and adenosine levels were measured. Cardiomyocytes were also exposed to dobutamine and dobutamine with ranolazine. Modeling was employed to determine whether ranolazine can bind to an enzyme that alters adenosine stores. Ranolazine was associated with increased adenosine levels in the absence (21.7 ± 3.0 vs. 9.4 ± 2.1 ng/mL, P < 0.05) and presence of ischemia (43.1 ± 13.2 vs. 23.4 ± 5.3 ng/mL, P < 0.05). Left ventricular end-systolic wall stress decreased (49.85 ± 4.68 vs. 57.42 ± 3.73 dyn/cm 2 , P < 0.05) and endocardial-to-epicardial myocardial blood flow ratio tended to normalize (0.89 ± 0.08 vs. 0.76 ± 0.10, P = nonsignificant). Adenosine levels increased in cardiac endothelial cells and cardiomyocytes when incubated with ranolazine that was reversed when cytosolic-5'-nucleotidase (cN-II) was inhibited. Point mutation of cN-II aborted an increase in its specific activity by ranolazine. Similarly, adenosine levels did not increase when cardiomyocytes were incubated with dobutamine. Modeling demonstrated plausible binding of ranolazine to cN-II with a docking energy of -11.7 kcal/mol. We conclude that the anti-adrenergic and cardioprotective effects of ranolazine-induced increase in tissue adenosine levels, likely mediated by increasing cN-II activity, may contribute to its beneficial effects in ischemic heart disease. NEW & NOTEWORTHY Ranolazine is a drug used for treatment of angina pectoris in patients with ischemic heart disease. We discovered a novel mechanism by which this drug may exhibit its beneficial effects. It increases coronary venous levels of adenosine both at rest and during dobutamine-induced myocardial ischemia. Ranolazine also increases adenosine levels in endothelial cells and cardiomyocytes in vitro, by principally increasing activity of the enzyme cytosolic-5'-nucleotidase. Adenosine has well-known myocardial protective and anti-adrenergic properties that may explain, in part, ranolazine's beneficial effect in ischemic heart disease.