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The naked mole-rat (NMR) is a unique long-lived rodent with low cancer incidence. Understanding the molecular mechanisms that NMR evolved to control aging and tumorigenesis is important for biomedicine. It is commonly accepted that the immune system has essential functions in the tumor growth control in animals. In-depth study of the NMR immune system has recently begun, thus peculiarities of antitumor response in these animals remain undiscovered. However, it was shown that myelopoiesis predominates in NMR, therefore it can be assumed that the innate immune cells in the naked mole rat contribute to the successful control of the cancer incidence and tumor growth. This brief provides an overview of ongoing research into the properties of naked mole rat macrophages. Recent study shown that naked mole rat peritoneal macrophages are capable of acquiring an inflammatory phenotype (M1) but polarization into an anti-inflammatory phenotype (M2) under standard stimulus is limited. A more in-depth study using transcriptome sequencing and immunometabolic profiling in novel in vitro model of naked mole rat bone marrow macrophages suggested by our group revealed non-canonical features of M1 as well as M2 phenotypes of naked mole rat macrophages, which can be associated with the evolutionary adaptation of the species. Continued study of the different polarization conditions of naked mole rat macrophages is important to determine unique adaptations in NMR antitumor immunity.

Substances of silver nanoparticles dialyzed through a 13 kDa membrane, synthesized in a medium of humic ligands modified with hydroquinone and 2-hydroxynaphthoquinone from PowHumus brown coal, specifically enhance the M2 properties of peritoneal macrophages due to inhibition of NO synthase and significant activation of arginase, thus enhancing anti-inflammatory properties of cells. In small, but effective concentrations, they do not have cytotoxic properties and do not contain pyrogenic impurities. The studied humates are able to influence the mechanisms of immune response formation and are an effective means for correcting inflammation and regeneration. [ABSTRACT FROM AUTHOR]

The aim of this study was to assess the production of reactive nitrogen species in the hearts of rats subjected to surgical trauma simulated against the background of post-traumatic stress disorder (PTSD). Materials and methods.The study was conducted on 42 white Wistar rats weighing 210-230 g, then divided into 6 groups: Group 1 consisted of intact animals, Group 2 included animals exposed to the induction of the PTSD model through single-prolonged stress (SPS), Group 3 – rats subjected to a sham operation, Group 4 – animals undergoing laparotomy, Group 5 – rats undergoing a sham surgical operation following SPS, and Group 6 – animals undergoing laparotomy under modeled SPS. NO synthase activity in the heart homogenate was determined spectrophotometrically. Results. The formation of peroxynitrite was assessed by the content of peroxynitrite of alkaline and alkaline-earth metals. SPS exposure significantly increases the production of reactive nitrogen species in the hearts of rats, in particular, it enhances NO synthase activity by activating the inducible isoform and reduces the activity of constitutive NO synthases, which is accompanied by the growth in the concentration of peroxynitrites. On the 7th day after laparotomy against the background of the experimental PTSD model, the indicators of nitrosative stress in the hearts of rats (total and inducible NO synthase activity and peroxynitrite concentration) significantly exceeded their values in the groups subjected to a single laparotomy and to a sham operation against the background of simulated SPS.

A restoration of low homoarginine (hArg) levels in obese ZSF1 rats (O-ZSF1) before (S1-ZSF1) and after (S2-ZSF1) the manifestation of heart failure with preserved ejection fraction (HFpEF) did not affect the worsening of cardiac HFpEF characteristics. Here, potential regulation of key enzymes of arginine metabolism in other organs was analyzed. Arginase 2 (ARG2) was reduced >35% in the kidney and small intestine of hArg-supplemented rats compared to O-ZSF1. Glycine amidinotransferase (GATM) was 29% upregulated in the kidneys of S1-ZSF1. Dimethylarginine dimethylaminohydrolase 1 (DDAH1) levels were reduced >50% in the livers of O-ZSF1 but restored in S2-ZSF1 compared to healthy rats (L-ZSF1). In the skeletal muscle, iNOS was lower in O-ZSF1 and further decreased in S1-ZSF1 and S2-ZSF1 compared to L-ZSF1. iNOS levels were lower in the liver of the S2-ZSF1 group but higher in the kidneys of S1-ZSF1 compared to L-ZSF1. Supplementation with hArg in an in vivo HFpEF model resulted in the inhibition of renal ARG2 and an increase in GATM expression. This supplementation might contribute to the stabilization of intestinal iNOS and ARG2 imbalances, thereby enhancing barrier function. Additionally, it may offer protective effects in skeletal muscle by downregulating iNOS. In the conceptualization of hArg supplementation studies, the current disease progression stage as well as organ-specific enzyme regulation should be considered. [ABSTRACT FROM AUTHOR]

The aim of the study was to evaluate the effect of curcumin on the ratio of constitutive and inducible NOS isoforms in the cerebral cortex of rats under a round-the-clock lighting (RCL) with a high fructose and fat diet. The experiments were performed on 21 white Wistar rats weighing 235±20 g, divided into 3 groups. Animals in the first group (control) received a standard diet (energy value 2720 kcal/kg) and were exposed to an equal alternation of light and darkness. The rats of the second and third groups were kept in RCL conditions against the background of the administration of a high-calorie carbohydrate-lipid diet (HCCLD, 4477 kcal/kg). In addition, animals of the third group received curcumin daily through a gavage, intragastrically, at a dose of 200 mg/kg. The activity of total NOS and its constitutive isoforms (cNOS) in the cerebral homogenate was measured, inducible isoenzyme (iNOS) activity and cNOS coupling index were calculated. Curcumin administration significantly reduced the total and inducible activity of NOS in the cerebral homogenate– by 34 and 38%, respectively, compared with the values of the second group. At the same time, cNOS activity (2.3-fold) and its coupling index (3.8-fold) increased significantly compared with the data of the second group. It is concluded that the use of curcumin in metabolic disorders associated with pathogenic factors of the “Western lifestyle” – light disorders and the use of HCCLD restores the normal ratio of constitutive and inducible NOS isoforms, cNOS coupling in the rat cerebral hemispheres, which prevents the development of oxidative-nitrosative stress.

Introduction. Helicobacter pylori (Hp) is a class I biological carcinogen and the third leading cause of cancer death in the world, according to the World Health Organization. Hp infection represents a global public health problem in the 4.4 billion people living with Hp worldwide. The pathogenesis of helicobacteriosis is multifaceted: disorders in the nitric oxide (NO) system are involved in the development of the disease, along with other mechanisms. These aspects of the pathogenesis of helicobacteriosis are not well understood. In particular, such parts of the general problem as the significance of changes in the level of NO, its metabolites in the development of inflammatory and erosive-ulcer diseases of the gastroduodenal zone caused by different genotypes of Hp are not solved. After HP eradication, the content of NO synthase in the gastric mucosa decreases. However, the expression of the enzyme remains high in areas of intestinal metaplasia, which is considered the source of continued production of NO synthase even after Hp eradication. Aim. To investigate the level of nitrates/nitrites in the blood in patients infected with various genotypes of Hp. Materials and methods. 48 patients with inflammatory and erosive-ulcer diseases of the stomach and CPD infected with Hp were examined. R&D Systems kits were used to determine the level of nitrates/nitrites in the blood. For the diagnosis of helicobacteriosis, a classic respiratory test was used, as well as a polymerase chain reaction. CagA, VacA, BabA, IceA genotyping Hp was performed. Depending on gene detection, Hp strains were divided into 4 serotypes: type I (CagA+, VacA+)/Type Ia (CagA+, VacA-), type Ib (CagA-, VacA+), type II (Vac A-, CagA-). Discussion. Нр harboured the CagA gene in 34 patients (70.8% of cases), VacA gene in 40 patients (83.3%), BabA gene in 6 patients (12.5%), and IceA gene in 8 patients (16.7%). The distribution by Нр serotype showed that serotype I was found in 28 patients (58.3%), serotype Ia in 6 patients (12.5%), serotype Ib in 12 patients (25.0%), and serotype II in 2 patients (4.2%). In general, all surveyed patients had blood levels of nitrates/nitrites that were significantly increased to 54.7±2.4 μmol/L (compared to the levels of healthy individuals, p

We studied the role of NO synthase in the infarct-limiting effect of short-term (SNH) and chronic continuous normobaric hypoxia (CNH). In male Wistar rats, SNH (6 sessions of 10-min hypoxia 8% O2 and 10-min reoxygenation) or CNH (12% O2 for 21 days) was modeled. In 30 min after SNH or 24 h after CNH, the rats were subjected to coronary artery occlusion (45 min) and reperfusion (2 h). The following drugs were administered to rats: non-selective NO synthase inhibitor L-NAME (10 mg/kg), inhibitor of inducible NO synthase S-methylthiourea (3 mg/kg), and inhibitor of neuronal NO-synthase 7-nitroindazole (50 mg/kg). NO donor diethylenetriamine was administered intravenously in a dose 2 mg/kg. It was found that L-NAME and S-methylthiourea abolished the infarct-limiting effect of SNH and CNH. Diethylenetriamine increased cardiac tolerance to ischemia/reperfusion. It is believed that inducible NO synthase plays an important role in the cardioprotective effect of normobaric hypoxia. [ABSTRACT FROM AUTHOR]

Cell-free system has emerged as a powerful platform with a wide range of in vitro applications and recently has contributed to express metabolic pathways for biosynthesis. Here we report in vitro construction of a native biosynthetic pathway for L-4-nitrotryptophan (L-4-nitro-Trp) synthesis using an Escherichia coli-based cell-free protein synthesis (CFPS) system. Naturally, a nitric oxide (NO) synthase (TxtD) and a cytochrome P450 enzyme (TxtE) are responsible for synthesizing L-4-nitro-Trp, which serves as one substrate for the biosynthesis of a nonribosomal peptide herbicide thaxtomin A. Recombinant coexpression of TxtD and TxtE in a heterologous host like E. coli for L-4-nitro-Trp production has not been achieved so far due to the poor or insoluble expression of TxtD. Using CFPS, TxtD and TxtE were successfully expressed in vitro, enabling the formation of L-4-nitro-Trp. After optimization, the cell-free system was able to synthesize approximately 360 μM L-4-nitro-Trp within 16 h. Overall, this work expands the application scope of CFPS for study and synthesis of nitro-containing compounds, which are important building blocks widely used in pharmaceuticals, agrochemicals, and industrial chemicals.

Nitric oxide as a therapeutic approach to the treatment of cardiovascular diseases attracted the attention of researchers at the end of the 19th century. As a vasodilator, nitric oxide may be a unique therapeutic agent for the treatment of hypertension and, as a result, renal failure and left ventricular hypertrophy.The aim of the article is to analyze the literature data on possible ways of modulating the activity of various nitric oxide synthases as an approach to the treatment of endothelial dysfunction.Materials and methods. When searching for materials for writing a review article, such abstract databases as PubMed, Google Scholar, e-Library, etc., were used. The search was carried out on the publications for the period from 1990 to 2021. The following words and phrases were chosen as parameters for the literature selection: nitric oxide; NO synthase; endothelial dysfunction; NO synthase activator; NO synthase inhibitor.The following words and phrases were chosen as parameters for the literature selection:Results. The article presents the history of the nitric oxide discovery and its biological role, the process of its biosynthesis, as well as the isoforms of its synthesizing enzymes (NOS): neuronal – nNOS, endothelial – eNOS and inducible iNOS, and their role in normal and pathological physiology. The process of NOS uncoupling (its molecular mechanisms) has been considered as the basis of endothelial dysfunction.The examples of the pharmacological correction (BH4, arginase inhibitors, statins, resveratrol) are presented. In addition, NO synthase activators (calcium dobesilate, cavNOxin, and some NOS transcription activators), as well as non-selective (L-NMMA, 1-NNA, L-NAME, ADMA, 546C88, VAS203) and selective (L-NIO, 7-nitroindazole, aminoguanidine, L-NIL, GW273629, GW274150, cavtratin) inhibitors of nitric oxide synthasehave been described.Conclusion. Nitric oxide synthases continue to be promising targets for the development of agents that modulate their activity to correct various pathologies. As a therapeutic approach, modulation of the nitric oxide synthase activity can be implemented to treat endothelial dysfunction, which is the cause for complications of many diseases.

Unlike pyramidal neurons, interneurons of the hippocampus are a heterogeneous group of neurons that differ in their morphological, cytochemical, and functional characteristics. The aim of this study was to conduct a comparative morphological analysis of nitroxidergic (NOS+) and calretinin-containing (CR+) nonpyramidal neurons of the CA1 and CA3 zones in the rat hippocampus using immunohistochemical methods. Qualitative and quantitative differences in NOS+ and CR+ populations of nonpyramidal neurons in different layers of the studied zones of the hippocampus were demonstrated. Differences in the quantitative composition of the studied populations of interneurons were also demonstrated in two subregions of the hippocampus that correspond to dorsal and intermediate hippocampus. It was established that NOS+ interneurons are more typical for the dorsal hippocampus, while a greater number of CR+ interneurons are presented in the intermediate hippocampus. Data obtained during the study can contribute to understanding the role of nonpyramidal neurons in the formation of functional specialization of different regions of the hippocampus. [ABSTRACT FROM AUTHOR]

IntroductionPhotosynthetic organisms respond to nitrogen (N) deprivation with the slowdown of photosynthesis and electron transport resulting in the balance the carbon (C)/N ratio. Under this extreme condition, organisms trigger complex mechanisms to keep growing using different N sources and recycling N containing molecules. In particular, phytoplankton are able to uptake L-arginine (L-Arg) as an organic N source. L-Arg can be assimilated mainly by the arginase, arginine deimidase, arginine decarboxylase or L-amino oxidase pathways.ResultsWe analyzed the effect of different N sources on the growth of the green algae Ostreococcus tauri. N starvation caused an inhibition of culture growth and a decrease in chlorophyll content. The addition of L-Arg to an N-deprived medium promotes a sustained growth rate of O. tauri culture and the increase of chlorophyll levels. The transcript level of genes involved in N uptake and metabolism were increased in N-starved condition while the addition of L-Arg as the sole N source reduced their induction. Since the O. tauri genome lacks the classical pathways to metabolize L-Arg, another enzyme/s may be responsible for L-Arg catabolism. Previously, we characterized the nitric oxide synthase (NOS) enzyme from O. tauri (OtNOS) which oxidizes L-Arg producing nitric oxide (NO) and citrulline. The NOS inhibitor L-NAME blocks the effect promoted by L-Arg on N-deprived O. tauri growth. Besides, NO level increased in O. tauri cells growing in L-Arg containing medium, suggesting the participation of OtNOS enzyme in L-Arg metabolism during N starvation.DiscussionOur hypothesis suggests that, after NOS-dependent Arg degradation, non-enzymatic oxidation of NO produces N oxides (mainly NO2-) that are re-incorporated to the N primary metabolism. As expected, N deprivation increases the lipid content in Ostreococcus. The addition of L-Arg or NO2- as the sole N sources showed a similar increase in lipid content to N deprivation. In summary, our results demonstrate that L-Arg is able to function as N source in Ostreococcus. The evidences on an alternative pathway of N supply and metabolism in a photosynthetic microorganism are discussed. These results could also allow the development of biotechnological tools for increasing lipid production for industry.

Methylene blue (MB) is the first fully synthetic compound that had found its way into medicine over 120 years ago as a treatment against malaria. MB has been approved for the treatment of methemoglobinemia, but there are premises for its repurposing as a neuroprotective agent based on the efficacy of this compound demonstrated in the models of Alzheimer's, Parkinson's, and Huntington's diseases, traumatic brain injury, amyotrophic lateral sclerosis, depressive disorders, etc. However, the goal of this review was not so much to focus on the therapeutic effects of MB in the treatment of various neurodegeneration diseases, but to delve into the mechanisms of direct or indirect effect of this drug on the signaling pathways. MB can act as an alternative electron carrier in the mitochondrial respiratory chain in the case of dysfunctional electron transport chain. It also displays the anti-inflammatory and anti-apoptotic effects, inhibits monoamine oxidase (MAO) and nitric oxide synthase (NOS), activates signaling pathways involved in the mitochondrial pool renewal (mitochondrial biogenesis and autophagy), and prevents aggregation of misfolded proteins. Comprehensive understanding of all aspects of direct and indirect influence of MB, and not just some of its effects, can help in further research of this compound, including its clinical applications. [ABSTRACT FROM AUTHOR]

Background. Diabetes mellitus is a chronic endocrine-metabolic disease caused by an absolute or relative insulin deficiency. During diabetes, there are perfect conditions for the development of oxidative stress: the content of substrates for oxidation increases, the content of natural antioxidants decreases and the activity of antioxidant systems is suppressed. It is known that photobiomodulation therapy produce antioxidant and antihyperglycemic effects. Here we investigated its influence on blood system functioning. Materials and Methods. The study was performed on male Wistar rats. Experimental diabetes mellitus was induced by the intraperitoneal injection of streptozotocin. Leukocyte formula was calculated using blood smears stained by Romanowsky–Giemsa. Catalase activity was determined spectrophotometrically. Affinity of hemoglobin to oxygen was evaluated by spectrophotometric method in Ivanov’s modification by drawing oxygenation curves. The protoporphyrin content in whole blood was measured by analyzing its fluorescence spectra. The content of NO2-, total and inducible NO synthase activity was determined spectrophotometrically. Results. Under the action of photobiomodulation therapy on healthy animals, there was a shift of oxygenation curves to the left and a decrease of P50, whereas under irradiation of rats with diabetes, there was a shift of oxygenation curves to the right and increase in P50 compared to indices in nonirradiated animals. During diabetes, there was a decrease in protoporphyrin content compared to control, but there was a tendency to increase under photobiomodulation. Photobiomodulation therapy of rats with diabetes increased catalase activity in erythrocyte hemolysates. We revealed significant changes in leukocyte formula under photobiomodulation. The total NO synthase activity in leukocytes of rats with diabetes was higher compared to healthy animals, but decreased under the action of photobiomodulation. We found an increase in inducible NO synthase activity in leukocytes of rats with diabetes and in leukocytes of irradiated healthy animals. An increase in NO2- content in leukocytes of rats with diabetes was detected. Under photobiomodulation, NO2- content was significantly lower in rats with diabetes. Conclusion. Photobiomodulation therapy produces a corrective action on blood system during diabetes, in particular, it improves oxygen release from hemoglobin and prevents hypoxia. Simultaneously with the increase in tissue oxygen saturation, a decrease in NO synthase activity and nitrite content along with an increase in catalase activity prevents the development of oxidative stress.

The cardioprotective effect of chronic hypoxia (CH) is associated with the activation of inducible nitric oxide synthase (iNOS). Reactive oxygen species (ROS) are involved in the development of CH-induced cardiac tolerance to ischemia/reperfusion. The infarct-limiting effect of CH depends on the opening of mitochondrial ATP-sensitive potassium (mitoKATP) channels. Protein kinase C δ and ε isoforms are involved in the cardioprotective effect of adaptation to hypoxia. CH increases the expression of phosphorylated extracellular signal-regulated kinase 1/2 (p-ERK1/2), Ca2+/calmodulin-dependent protein kinase II (CaMKII), phosphorylated p38 (p-p38), phosphorylated AMP-activated protein kinase (p-AMPK), as well as hexokinase-1 (HK1) and hexokinase-2 (HK2). ERK1/2 and mitogen-activated protein kinases (MEK1/2) are involved in the cardioprotective effect of adaptation to hypoxia. The role of atrial natriuretic peptide (ANP), erythropoietin, endothelin-1, phosphoinositide 3-kinases (PI3K), protein kinase G (PKG), c-Jun N-terminal kinase (JNK), and p38 mitogen-activated protein kinase (p38 MAPK) in the protective effect of adaptation to hypoxia requires further research. [ABSTRACT FROM AUTHOR]

The aim of the research was to investigate the effect of chromium and zinc citrates on the NO-synthase (NOS) activity of erythrocytes in rats with streptozotocin diabetes. In three series of investigations rats were divided into four groups (I — control, II, III and IV — experimental) each one containing 7 animals. During four weeks, in the first series of investigations chromium citrate was added with water to the main diet of animals in III and IV groups in amounts of 10 and 25 μg Cr3+/kg of body weight; in the second series, zinc citrate was added in amounts of 20 and 50 mg Zn2+/kg of body weight respectively. In the third series, the animals of III group received chromium citrate in amount 25 μg Cr3+/kg of body weight and zinc citrate in amount 50 mg Zn2+/kg of body weight with water. The rats of II experimental group in all series received clean water with no citrates added. A month later, in animals of all experimental groups on the background of a 24-hour fasting an experimental diabetes mellitus was induced by a single intraperitoneal injection of streptozotocin in amounts of 45 mg/kg of body weight with the previous injection of nicotinamide. Diabetes occurred on the third day. Animals with a glucose concentration of 14 mmol/L were used for the experiment. The material for the investigation was the blood of rats, in which the concentration of glucose and the relative count of glycosylated hemoglobin were determined, in erythrocytes — NO-synthase activity: general, inducible and constitutive. As a result of the conducted research, it has been found that under streptozotocin induced experimental diabetes in erythrocytes of rats of experimental group II in both series of investigations the activity of general and inducible NOS increased, while the activity of the constitutive NOS did not change compared with the animals of the control group. The introduction of chromium and zinc citrates into the animals’ diet in the above mentioned doses led to the decrease in the activity of the general and inducible NOS compared with the animals of group II with streptozotocin diabetes, indicating a positive effect of the studied microelements on NOS activity in erythrocytes of rats. Thus, the use of chromium and zinc citrates in the diet of rats with diabetes has a normalizing effect on the state of NOS activity, what can reduce the harmful influence of hyperglycemia on the development of oxidative and nitrosative stress.

The in vitro addition of water-soluble polysaccharides isolated from the leaves of Crataegus sanguinea Pall. to culture of mouse peritoneal macrophages induced classical activation of antigen-presenting cells by increasing NO synthase activity and reducing arginase expression. [ABSTRACT FROM AUTHOR]

Cationic amino acid transporters (CATs) play a central role in the supply of the substrate L-arginine to intracellular nitric oxide synthases (NOS), the enzymes responsible for the synthesis of nitric oxide (NO). In heart, NO produced by cardiac myocytes has diverse and even opposite effects on myocardial contractility depending on the subcellular location of its production. Approximately a decade ago, using a combination of biophysical and biochemical approaches, we discovered and characterized high- and low-affinity CATs that function simultaneously in the cardiac myocyte plasma membrane. Later on, we reported a negative feedback regulation of NO on the activity of cardiac CATs. In this way, NO was found to modulate its own biosynthesis by regulating the amount of L-arginine that becomes available as NOS substrate. We have recently solved the molecular determinants for this NO regulation on the low-affinity high-capacity CAT-2A. This review highlights some biophysical and biochemical features of L-arginine transporters and their potential relation to cardiac muscle physiology and pathology. [ABSTRACT FROM AUTHOR]

The review summarizes the latest data on the identification and synthesis of nitric oxide in fungi, as well as the mechanisms of NO action in these organisms, including S-nitrosylation and the nitration of amino acid residues, the initiation of DNA breaks, transcriptional gene activation, and the cGMP-dependent signaling pathway. Particular attention is paid to the NO-dependent regulation of such processes as apoptosis and various stress responses, spore germination, mycelium growth, and fungal differentiation. [ABSTRACT FROM AUTHOR]

It is well known that nitric oxide (NO) is involved in forming signal memory for stimulation of different modalities. We studied the involvement of nitric oxide in processes of the reconsolidation (repeated consolidation of a long-term memory on reminding) of conditioned reflex contextual fear memory in rats. After a single training session, animals demonstrated significant increases in freezing on presentation of the conditioned context. Reactivation of this memory on the background of blockade of de novo protein synthesis with cycloheximide led to a significant decrease in freezing time in the conditioned context in rats. Administration of the selective neuronal NO synthase blocker 3-bromo-7-indazole in conditions of memory reactivation on the background of protein synthesis blockade prevented weakening of conditioned reflex freezing reactions, as demonstrated by subsequent testing of animals in the conditioned context. In addition, administration of 3-bromo-7-indazole without reactivation did not elicit significant changes in measures of conditioned reflex freezing in rats. These results suggest that nitric oxide is involved in the labilization of conditioned reflex contextual fear memory on reminding, and is thus a necessary component of the triggering of the reconsolidation process. [ABSTRACT FROM AUTHOR]

Despite an established role of mitochondrial dysfunction in cardiac ischemia/reperfusion (I/R) injury, the upstream activators have remained incompletely defined. We have recently identified an innovative role of exogenously applied netrin-1 in cardioprotection, which is mediated by increased nitric oxide (NO) bioavailability. Here, we tested the hypothesis that this "pharmacological" treatment of netrin-1 preserves mitochondrial function via novel mechanisms that are NO dependent. Freshly isolated C57BL6 mouse hearts were perfused using a Langendorff system, and subjected to a 20min global ischemia/60min reperfusion, in the presence or absence of netrin-1. I/R induced marked increases in infarct size, total superoxide and hydrogen peroxide production, activity and protein abundance of NADPH oxidase (NOX) isoform 4 (NOX4), as well as impaired mitochondrial integrity and function, all of which were attenuated by netrin-1. This protective effect of netrin-1 is attributed to cGMP, a downstream effector of NO. The protein levels of NOX1 and NOX2 were however unaffected, and infarct size from NOX1 and NOX2 knockouts was not different from wild type animals. Scavenging of NO with PTIO reversed inhibitory effects of netrin-1 on NOX4, while NO donor attenuated NOX4 protein abundance. In vivo NOX4 RNAi, or sepiapterin perfusion, resulted in recoupling of NOS, decreased infarct size, and blockade of dysfunctional mitochondrial swelling and mitochondrial superoxide production. These data demonstrate that netrin-1 induces cardioprotection through inhibition of NOX4 activity, which leads to recoupling of NOS, augmented NO bioavailability, reduction in oxidative stress, and ultimately preservation of mitochondrial function. The NO-dependent NOX4 inhibition connects with our previously established pathway of DCC/ERK1/2/eNOS/NO/DCC feed-forward mechanism, to maintain NOS in the coupling state to attenuate oxidative stress to preserve mitochondrial function. These findings may promote development of novel therapeutics for cardiac I/R injury. This article is part of a Special Issue entitled "Mitochondria: From Basic Mitochondrial Biology to Cardiovascular Disease".

Abstract We hypothesized acute moderate and drastic reductions in uric acid concentration exert different effects on arterial function in healthy normotensive and hypertensive adults. Thirty‐six adults (aged 58 [55;63] years) with or without primary hypertension participated in a three‐way, randomized, double‐blind, crossover study in which [placebo] and [febuxostat] and [febuxostat and rasburicase] were administered. Febuxostat and rasburicase reduce the uric acid concentration by xanthine oxidoreductase inhibition and uric acid degradation into allantoin, respectively. Endothelial function was assessed in response to acetylcholine, sodium nitroprusside, heating (with and without nitric oxide synthase inhibition) using a laser Doppler imager. Arterial stiffness was determined by applanation tonometry, together with blood pressure, renin–angiotensin system activity, oxidative stress, and inflammation. Uric acid concentration was 5.1 [4.1;5.9], 1.9 [1.2;2.2] and 0.2 [0.2;0.3] mg/dL with [placebo], [febuxostat] and [febuxostat–rasburicase] treatments, respectively (p

We hypothesized acute moderate and drastic reductions in uric acid concentration exert different effects on arterial function in healthy normotensive and hypertensive adults. Thirty‐six adults (aged 58 [55;63] years) with or without primary hypertension participated in a three‐way, randomized, double‐blind, crossover study in which [placebo] and [febuxostat] and [febuxostat and rasburicase] were administered. Febuxostat and rasburicase reduce the uric acid concentration by xanthine oxidoreductase inhibition and uric acid degradation into allantoin, respectively. Endothelial function was assessed in response to acetylcholine, sodium nitroprusside, heating (with and without nitric oxide synthase inhibition) using a laser Doppler imager. Arterial stiffness was determined by applanation tonometry, together with blood pressure, renin–angiotensin system activity, oxidative stress, and inflammation. Uric acid concentration was 5.1 [4.1;5.9], 1.9 [1.2;2.2] and 0.2 [0.2;0.3] mg/dL with [placebo], [febuxostat] and [febuxostat–rasburicase] treatments, respectively (p < 0.0001). Febuxostat improved endothelial response to heat particularly when nitric oxide synthase was inhibited (p < 0.05) and reduced diastolic and mean arterial pressure (p = 0.008 and 0.02, respectively). The augmentation index decreased with febuxostat (ANOVA p < 0.04). Myeloperoxidase activity profoundly decreased with febuxostat combined with rasburicase (p < 0.0001). When uric acid dropped, plasmatic antioxidant capacity markedly decreased, while superoxide dismutase activity increased (p < 0.0001). Other inflammatory and oxidant markers did not differ. Acute moderate hypouricemia encompasses minor improvements in endothelial function, blood pressure, and arterial stiffness. Clinical Trial Registration: NCT03395977, https://clinicaltrials.gov/ct2/show/NCT03395977 [ABSTRACT FROM AUTHOR]

One of the important medical and social present-day problems is atrial fibrillation (AF) which prevalence in the adult population is 2 % for persons under 65 and 9 % for those over 65 years of age and it is a common cause of ischemic stroke. The embolic complications incidence is 2.1 % per year in patients with paroxysmal AF, and 3.0 % per year in patients with persistent AF. The aim of the study is to analyze the modern literary sources related to the role of gene polymorphisms regulating some neurohumoral systems in group of patients with atrial fibrillation. A combination of certain genes polymorphisms can contribute to AF risk. Especially important are gene studies of the renin-angiotensin-aldosterone system (RAAS) role in the pathogenesis of AF which are currently being studied with a particular intensity. Recent data show that activation of RAAS plays an important role in the development and recurrence of AF. These studies are of great practical interest as the associative effect of angiotensin converting enzyme (ACE) inhibitors in the prevention of AF has been identified. AGT gene encodes a plasma protein known as angiotensinogen. This protein is expressed in the liver and is cleaved by the enzymatic renin action in response to lower blood pressure. The resulting product, angiotensin I, is then cleaved by ACE to the physiologically active enzyme angiotensin II. Defects in this gene may also be associated with non-hereditary AF. More than 16 spot mutations in the AGT gene were discovered, most of which resulted in amino acid substitutions. Conclusions. The analysis of the literature allows to conclude that, first, genetic polymorphisms may influence both the severity of pathological changes in the body and the efficacy of pharmacotherapy, and second, the study of RAAS gene polymorphisms may allow early detection of persons with increased risk of persistent AF recurrence and its prevention.

This study was focused on the mechanisms of the protective effects of L-arginine and the nitric oxide donor SNAP under the induction of cyclosporine A-dependent mitochondrial permeability transition pore (MPTP) by excess of Ca2+ or D,L-palmitoylcarnitine (PC). The possible involvement of a signaling system that included mitochondrial enzymes NO-synthase (mtNOS), guanylate cyclase (GC), and cGMP-dependent protein kinase G (PKG) (mtNOS/GC/PKG-SS) in the regulation of MPTP was investigated. The experiments were performed on isolated liver mitochondria using inhibitory analysis. The results of the study have shown that L-arginine and SNAP caused a dose-dependent effects on the opening of MPTP. L‑Arginine and SNAP at low concentrations (5–100 μM) activated protective mechanisms, providing an increase in the mitochondrial calcium buffer capacity (CRC) and the critical (threshold) concentration of palmitoylcarnitine (PC*) required for MPTP induction. At higher concentrations, L-arginine (more than 500 μM) and SNAP (more than 100 μM) caused the opposite effect, that is, they suppressed respiration and promoted pore opening. Inhibitors of NOS, GC, and PKG eliminated the protective effects observed at low concentrations of L‑arginine and SNAP. The experiments conducted with a specific inhibitor of inducible NOS (W1400) showed that this calcium-independent enzyme did not participate in the regulation of MPTP in our experiments. Based on the results obtained, it can be assumed that the calcium-dependent mitochondrial signaling system mtNOS/GC/PKG-SS is involved in the regulation of MPTP, providing an increase in CRC and PC*. At high concentrations of L-arginine or SNAP, excess of NO overcame the protection provided by mtPKG and promoted pore opening. [ABSTRACT FROM AUTHOR]

In plants, nitric oxide synthase (NOS)-like or nitrate reductase (NR) produces nitric oxide (NO), which is involved in releasing seed dormancy. However, its mechanism of effect in potato remains unclear. In this study, spraying 40 μM sodium nitroprusside (SNP), an exogenous NO donor, quickly broke tuber dormancy and efficiently promoted tuber sprouting, whereas 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (c-PTIO), an NO scavenger, repressed the influence of NO on tuber sprouting. Compared with the control (distilled water), SNP treatment led to a rapid increase in NO content after 6 h and a decreased abscisic acid (ABA) content at 12 and 24 h. c-PTIO treatment significantly inhibited increase of NO levels and increased ABA production. In addition, NG-nitro-L-arginine methyl ester, an NOS inhibitor, clearly inhibited the NOS-like activity, whereas tungstate, an NR inhibitor, inhibited the NR activity. Furthermore, NO promoted the expression of a gene involved in ABA catabolism (StCYP707A1, encoding ABA 8′-hydroxylase) and inhibited the expression of a gene involved in ABA biosynthesis (StNCED1, encoding 9-cis-epoxycarotenoid dioxygenase), thereby decreasing the ABA content, disrupting the balance between ABA and gibberellin acid (GA), and ultimately inducing dormancy release and tuber sprouting. The results demonstrated that NOS-like or NR-generated NO controlled potato tuber dormancy release and sprouting via ABA metabolism and signaling in tuber buds.

The purpose of this study was the assessment of asymmetric dimethylarginine (ADMA) and its links with carbohydrate and lipid metabolism parameters in patients with acute myocardial infarction (AMI) and type 2 diabetes mellitus following determination of asymmetric dimethylarginine and NO synthase plasma levels. Materials and methods. The study included examination of 73 patients with acute myocardial infarction and type 2 diabetes mellitus, 57 patients with AMI without type 2 diabetes and 20 conditionally healthy individuals. The content of ADMA and NO synthase was measured by using an enzyme-linked immunosorbent assay kit (ADMA Xpress ELISA kit;Immundiagnostik,Austria) and Bender MedSystem (Austria), respectively. The parameters of carbohydrate and lipid metabolism were determined by a standard biochemical method. Results. A significant 2.64 times increased level of ADMA (1.24 ± 0.04 μmol/L) was found in the patients with AMI and type 2 diabetes compared to the practically healthy persons (control group) (0.47 ± 0.05 μmol/L), and 2.53 times increased (P < 0.05) in comparison with the patients without type 2 diabetes. In the presence of type 2 diabetes the 40.1 % (P < 0.05) decrease in NOs level was noted compared to the control group (3.12 ± 0.11ng / ml and 5.21 ± 0.19 ng/ml, respectively) and the 26.1 % (P < 0.05) decrease compared to the patients with AMI without type 2 diabetes. The study provided a possibility to determine a direct correlation between ADMA and total cholesterol (r = 0.47; P < 0.05); LDL cholesterol (r = 0.28; P < 0.05), HDL cholesterol (r = -0.39; P < 0.05), triglycerides (P = 0.35; P < 0.05), glucose (P = 0.46; P < 0.05), insulin = 0.49; P < 0.05), glycosylated hemoglobin (r = 0.39; P < 0.05). Correlation analysis showed an inverse correlation between ADMA and NO synthase levels (r = -0.67; P < 0.05). Conclusions. The association between asymmetric dimethylarginine high levels and pathological changes in the parameters of carbohydrate, lipid metabolism and endothelial dysfunction has been established, which increases ischemia in the vessel wall and adversely affects the course and prognosis of acute myocardial infarction in patients with type 2 diabetes mellitus.

Addition of water-soluble polysaccharides isolated from Conium maculatum L. to the mouse peritoneal macrophage culture induces classical activation of antigen-presenting cells due to an increase in NO synthase activity and a decrease in arginase expression. [ABSTRACT FROM AUTHOR]

Nitric-oxide synthase activity was detected in Neurospora crassa cells with the measurement of the conversion of 3H-L-arginine to 3H-L-citrulline. Some characteristics of this activity (sensitivity to calcium ions, action of specific enzyme inhibitors, and western blot analysis) were similar to those of an inducible enzyme found in mammals. According to western blotting, the molecular weight of NO synthase was around 130 kDa. No light-dependent changes in the specific activity of NO synthase were revealed in the photocarotenogenesis and photoconidiation of N. сrassa. [ABSTRACT FROM AUTHOR]

In plants, nitric oxide synthase (NOS)-like or nitrate reductase (NR) produces nitric oxide (NO), which is involved in releasing seed dormancy. However, its mechanism of effect in potato remains unclear. In this study, spraying 40 μM sodium nitroprusside (SNP), an exogenous NO donor, quickly broke tuber dormancy and efficiently promoted tuber sprouting, whereas 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (c-PTIO), an NO scavenger, repressed the influence of NO on tuber sprouting. Compared with the control (distilled water), SNP treatment led to a rapid increase in NO content after 6 h and a decreased abscisic acid (ABA) content at 12 and 24 h. c-PTIO treatment significantly inhibited increase of NO levels and increased ABA production. In addition, N G -nitro-L-arginine methyl ester, an NOS inhibitor, clearly inhibited the NOS-like activity, whereas tungstate, an NR inhibitor, inhibited the NR activity. Furthermore, NO promoted the expression of a gene involved in ABA catabolism (StCYP707A1 , encoding ABA 8′-hydroxylase) and inhibited the expression of a gene involved in ABA biosynthesis (StNCED1 , encoding 9- cis -epoxycarotenoid dioxygenase), thereby decreasing the ABA content, disrupting the balance between ABA and gibberellin acid (GA), and ultimately inducing dormancy release and tuber sprouting. The results demonstrated that NOS-like or NR-generated NO controlled potato tuber dormancy release and sprouting via ABA metabolism and signaling in tuber buds. [ABSTRACT FROM AUTHOR]

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Background: Warionia saharae Bentham & Cosson. is used in traditional medicine to treat many diseases including hypertension. Method: The present study was designed to investigate the antihypertensive activity of aqueous extract of Warionia saharae (WSLAE) in anesthetized L-NAME (Nω-L-arginine methyl ester)-induced rats. The acute and sub-chronic effects of WSLAE on systolic, diastolic, mean arterial blood pressure and heart rate (HR) were investigated after oral administration of the extract (100 mg/kg body weight of WSLAE) during 6 h for the acute experiment and during 7 days for the sub-chronic test. In addition the effect of WSLAE on the contractile response of isolated rat aortic rings was tested and the role of the vascular receptors was evaluated using several drugs. Results: The results showed that WSLAE induced a significant decrease in the systolic, diastolic, mean arterial blood pressure and HR in both normotensive and hypertensive rats. Furthermore, this extract induced relaxation in rings pre-contracted with Epinephrine (10 µM) or with KCl (100 mM). This vasorelaxant capacity seems to be mediated through inhibition of KATP channels and nitric oxide (NO) synthase pathways. Conclusion: This study supports the use of Warionia saharae in the management of hypertension in Moroccan traditional medicine. [ABSTRACT FROM AUTHOR]

Endothelin-1 (ET-1) is a powerful vasoconstrictor peptide considered to be causally implicated in hypertension and the development of cardiovascular disease. Increased ET-1 is commonly associated with reduced NO bioavailability and impaired vascular function; however, whether chronic elevation of ET-1 directly impairs endothelium-dependent relaxation (EDR) remains elusive. Herein, we report that (1) prolonged ET-1 exposure (ie, 48 hours) of naive mouse aortas or cultured endothelial cells did not impair EDR or reduce eNOS (endothelial NO synthase) activity, respectively (P>0.05); (2) mice with endothelial cell-specific ET-1 overexpression did not exhibit impaired EDR or reduced eNOS activity (P>0.05); (3) chronic (8 weeks) pharmacological blockade of ET-1 receptors in obese/hyperlipidemic mice did not improve aortic EDR or increase eNOS activity (P>0.05); and (4) vascular and plasma ET-1 did not inversely correlate with EDR in resistance arteries isolated from human subjects with a wide range of ET-1 levels (r=0.0037 and r=-0.1258, respectively). Furthermore, we report that prolonged ET-1 exposure downregulated vascular UCP-1 (uncoupling protein-1; P<0.05), which may contribute to the preservation of EDR in conditions characterized by hyperendothelinemia. Collectively, our findings demonstrate that chronic elevation of ET-1 alone may not be sufficient to impair EDR. [ABSTRACT FROM AUTHOR]

The involvement of the mitochondrial calcium-dependent NO synthase (mtNOS) in the regulation of mitochondrial respiration has not been sufficiently studied. Moreover, the possible functioning of a mitochondrial signaling system involving mtNOS/guanylate cyclase (GC)/protein kinase G (PKG) and the impact of this system (mtNOS/GC/PKG-SS) on mitochondrial respiration have not yet been analyzed. To investigate this issue, we performed experiments on isolated rat liver using specific inhibitors of NOS, GC, and PKG. The high rate of mitochondrial respiration was supported by pyruvate and glutamate or by succinate in the presence of hexokinase, glucose, and ADP. It was shown that L-arginine and the NO donor sodium nitroprusside (SNP) exert concentration-dependent effects on the mitochondrial respiration rate. At low concentrations, L‑arginine (up to 200 μM) and SNP (up to100 μM) activated mitochondrial respiration. The inhibitors of NOS, GC, and PKG eliminated this effect indicating that mtNOS/GC/PKG-SS is involved in the activation of respiration. At high concentrations, L-arginine and SNP, on the contrary, inhibited respiration. Under these conditions, the inhibitors of GC and PKG enhanced the inhibition of respiration, which indicates an opposite effect of the excess of NO and PKG on the mitochondrial respiration. The results suggest that the functioning of calcium-dependent mtNOS/GC/PKG-SS can ensure the activation of respiration at low concentrations of L-arginine or SNP in the medium. [ABSTRACT FROM AUTHOR]

The roles of NO synthase and ATP-dependent K+ channels (KATP channels) in the development of the infarct-limiting effect of early hypoxic preconditioning (HP) in rats were studied and the potential for pharmacological simulation of this phenomenon was demonstrated. HP was modeled by alternation of six 10-min sessions of normobaric hypoxia (8% O2) and six 10-min periods of reoxygenation with atmospheric oxygen (21% O2). The total duration of the adaptive action was 120 min. These results indicate that NO synthase and KATP channels play the role of mediators in the signal mechanism of HP. NO donors and KATP channel activators allow the protective effect of hypoxic preconditioning to be reproduced by administration 1 h before ischemia/reperfusion but not when given 2 h 30 min before coronary occlusion. [ABSTRACT FROM AUTHOR]

The fertility of female mammals depends on the quality of oocytes, which decreases in the process of biological aging. We found an inhibitory effect of two related pituitary hormones (prolactin (PRL) and growth hormone (GH)) on destructive modifications of metaphase chromosomes in the eggs of domestic cow (Bos taurus taurus), aging in vitro. The involvement of different NO synthase (NOS) isoforms in realization of the effect of PRL and GH on age-related changes of MII chromosomes with prolonged cultivation of in vitro matured cow oocytes was studied in the present work. In the absence of hormones NPLA, neuronal NOS (nNOS) inhibitor had no effect on the frequency of chromosomal abnormalities in aging oocytes. At the same time, 1400 W (inducible NOS (iNOS) inhibitor) and L-NAME (efficient endothelial NOS (eNOS and nNOS) inhibitor) decreased this frequency, while the blocking of all three NO synthase isoforms led to the opposite effect. The inhibitory effect of PRL on destructive chromosome modifications in aging eggs increased in the presence of L-NAME, but was not expressed with the inhibition of nNOS, iNOS, or all NO synthase isoforms simultaneously. Neither NPLA nor L-NAME modulated the inhibitory effect of GH on abnormal chromosome changes in oocytes. On the contrary, the blocking of iNOS, as well as all three NO synthase isoforms, led to an increase in the portion of oocytes with destructive changes of MII chromosomes. At the same time, the level of total activity of NO synthase in oocytes did not depend on the presence of the studied hormones or NOS inhibitors during the prolonged cultivation of oocyte–cumulus complexes. Data obtained suggest that the inhibitory effect of PRL and GH on abnormal changes of metaphase chromosomes in aging cow eggs is associated with a decrease in the activity of endothelial NO synthase, as well as (in the case of PRL) with an increase in the activity of neuronal NO synthase in the cumulus cells surrounding the oocytes. [ABSTRACT FROM AUTHOR]

The cardioprotective and inotropic effects of standardized active natural substance based on high-molecular-weight compounds of humic origin were studied on the model of global ischemia (40 min) and reperfusion of isolated perfused rat heart. Preventive administration of the test substance (0.1 mg/ml) before ischemia/reperfusion modeling reduced reperfusion contracture and necrotic death of cardiomyocytes and promoted recovery of myocardial contractility. Blockade of NO synthase with L-NAME (100 μM) abolished the above effects of the test substance. It was hypothesized that NO synthase plays an important role in the development of the cardioprotective and inotropic effects of the test natural substance. [ABSTRACT FROM AUTHOR]

Objectives. To determine the location, percentage composition, and morphometric properties of sympathetic preganglionic neurons containing NO synthase (NOS) in the spinal cord in rats. Materials and methods. Studies were performed on 35 white female Wistar rats aged 3, 10, 20, 30, and 60 days, six months, and three years. Spinal cord sections made at the level of segment T2 were used for immunohistochemical detection of NOS and the acetylcholine-synthesizing enzyme choline acetyltransferase (CAT). The areas of nerve cells and the proportions of immunoreactive neurons were determined. Results. Most sympathetic preganglionic neurons in the spinal cords of neonatal and 10-day-old rats contained NOS and also CAT. Rats of these age groups also contained a population of NOS-positive/CAT-negative neurons (26% in neonates and 8% in 10-day-old animals), which was not seen in older animals. During the first 20 days, the proportion of NOS-immunopositive neurons decreased significantly, while that of CAT-positive neurons increased. Conclusions. In early postnatal ontogeny there was a decrease in the number of sympathetic preganglionic neurons expressing NOS, which may have influences on the mechanisms of NO-ergic sympathetic transmission. [ABSTRACT FROM AUTHOR]

Objectives. To determine the locations, percentage composition, and morphometric characteristics of sympathetic preganglionic neurons containing NO synthase (NOS) in the spinal cord of rats. Materials and methods. Experiments were performed on 35 white female Wistar rats aged 3, 10, 20, 30, and 60 days, 6 months, and 3 years. Immunohistochemical detection of NOS and the acetylcholine synthesis enzyme choline acetyltransferase (CAT) was performed on sections of spinal cord made at the level of segment T2. The areas of nerve cells and the proportions of immunoreactive neurons were determined. Results. Most sympathetic preganglionic neurons in the spinal cord of neonates and 10-day-old rats contained both NOS and CAT. At these age groups, rats also had a population of NOS-positive/CAT-negative neurons (26% in neonates and 8% in 10-day-old animals), this population was not seen in older animals. During the first 20 days, the proportion of NOS-immunopositive neurons decreased significantly, while the population of CAT-positive neurons increased. Conclusions. There was a reduction in the number of sympathetic preganglionic neurons expressing NOS during early postnatal ontogeny, which may influence the mechanisms of NO-ergic sympathetic transmission. [ABSTRACT FROM AUTHOR]

The progression from neoplastic initiation to malignancy happens in part because of the failure of immune surveillance. Cancer cells successfully escape immune recognition and elimination and create an immune-suppressive microenvironment. A suppressive metabolic microenvironment may also contribute to ineffective T-cell function. Tumor progression is characterized by a complex network of interactions among different cell types that cooperatively exploit metabolic reprogramming. As we start to recognize that cancer cells use different metabolism processes than normal cells do, a better understanding of the functional mechanisms of the regulation and reprogramming of the metabolic landscape in cancer cells is crucial to successful immunotherapy strategies. However, the exact role of metabolism in T cells and in the tumor microenvironment is not known. One pathway that plays an important role in the regulation of immune cell reactivity is arginine metabolism, which has complex cellular functions. l-arginine and its downstream metabolites (e.g., ornithine and citrulline) could be essential to T-cell activation and thus modulate innate and adaptive immunity to further promote tumor survival and growth. Identifying metabolic targets that mediate immunosuppression and are fundamental to sustaining tumor growth is key to increasing the efficacy of immunotherapies.

The effects of a non-selective blocker of NO synthases LNNA in a dose of 25 mg/kg and nitrates KNO3, NaNO3, Mg(NO3)2, and Ca(NO3)2 in doses of 5 and 50 mg/kg were studied on the model of experimental ischemic stroke induced by bilateral occlusion of the common carotid arteries. Wistar rats were randomized into 40 treatment (n=960) and 8 control (n=192) groups. Treatment group rats received injection of either nitrate, or LNNA, or a combination LNNA+nitrate. All substances were administered intraperitoneally 1 h prior to brain ischemia or 5 sec after occlusion of the common carotid arteries. Control rats received the same volume of 0.9% NaCl at the same terms. The non-selective inhibitor of NO synthases LNNA administered against the background of brain ischemia increased neurological deficit and animal mortality. Nitrate/nitrite reductase system had protective properties depending on the cation of nitrate and concentration of a nitrate during inhibition of NO synthase system under conditions of brain ischemia and hypoxia. [ABSTRACT FROM AUTHOR]

We investigated the influence of simvastatin, a statin, on the secretion of catecholamines (CA) in rat adrenal glands, and clarified its action mechanism. Simvastatin suppressed acetylcholine (ACh)-evoked CA release in a dose- and time-dependent fashion. In the presence of simvastatin, CA secretion evoked by 1.1-dimethyl-4-phenyl piperazinium iodide (DMPP), angiotensin II, high K+, veratridine, and Bay-K-8644 was time-dependently inhibited. However, in the simultaneous presence of simvastatin and Nω-nitro-l-arginine methyl ester hydrochloride, CA secretion evoked by angiotensin II and DMPP recovered to control levels. Adrenal NO release was increased by simvastatin-treatment. Simvastatin-inhibited CA secretion was not affected by treatment with mevalonate. Pravastatin did not influence ACh-evoked CA secretion, while atorvastatin reduced it. In the simultaneous presence of simvastatin and fimasartan, ACh-induced CA release was markedly reduced compared to that of fimasartan-treatment alone. We present the first evidence that simvastatin reduces adrenal CA secretion induced by stimulation of nicotinic and AT1-receptors. Simvastatin-induced inhibition seems to involve reducing the influx of both Ca2+ and Na+ into adrenochromaffin cells, partly via the elevation of NO production by NO synthase activation, without inhibition of 3-hydroxy-methylglutaryl coenzyme A reductase. Co-administration of simvastatin and fimasartan may be clinically helpful for the treatment of cardiovascular diseases. [ABSTRACT FROM AUTHOR]

It has been shown that calpains are involved in the proteolysis of muscle proteins that occurs with eccentric contraction (ECC) and that exogenously applied nitric oxide decreases the calpain-mediated proteolysis. The aim of this study was to examine the effects of ingestion of L-arginine (ARG), a nitric oxide precursor, on ECC-related calpain activation. In the first and second experiments, male Wistar rats were given ARG in water for 7 days starting from 3 days before the ECC protocol (average ingestion, ~600 mg kgbody wt-1 day-1). Tibialis anterior muscles underwent 200 repeated ECCs and, subsequently, were excised 3 days later. Whole muscle analyses (the first experiment) revealed that ARG attenuated ECC-induced force deficit and autolysis of calpain-1, and increased the amounts of S-nitrosylated calpain-1. Regarding ryanodine receptor (RyR) and dihydropyridine receptor (DHPR), ECC-induced proteolysis was completely inhibited by ARG, whereas the inhibition was partial for junctophilin-1 (JP1). Skinned fiber analyses (the second experiment) showed that ARG also inhibited ECC-elicited reductions in the ratio of depolarization-induced to maximum Ca2+-activated force. In the third experiment, homogenates of rested muscles were treated with S-nitrosylating agent, S-nitrosoglutathione (GSNO), and/or high Ca2+ concentration ([Ca2+]). Treatment with high [Ca2+] and without GSNO produced proteolysis of RyR, DHPR, and JP1. On the other hand, treatment with high [Ca2+] and GSNO caused complete inhibition of RyR and DHPR proteolysis and partial inhibition of JP1 proteolysis. These results indicate that ARG ingestion can attenuate ECC-induced proteolysis of Ca2+ regulatory proteins and force deficit by decreasing calpain activation via S-nitrosylation. [ABSTRACT FROM AUTHOR]

Posttraumatic stress disorder (PTSD) is associated with myocardial injury, but changes in coronary regulatory mechanisms in PTSD have not been investigated. This study evaluated the effect of PTSD-inducing stress on coronary tone and its regulation by nitric oxide (NO) and voltage-gated K channels. PTSD was induced by exposing rats to predator stress, 15 min daily for 10 days, followed by 14 stress-free days. Presence of PTSD was confirmed by the elevated plus-maze test. Coronary tone was evaluated from changes in coronary perfusion pressure of Langendorff isolated hearts. Predator stress induced significant decreases in coronary tone of isolated hearts and in blood pressure of intact rats. L-NAME, a non-selective NO synthase (NOS) inhibitor, but not S-MT, a selective iNOS inhibitor, and increased coronary tone of control rats. In PTSD rats, both L-NAME and S-MT increased coronary tone. Therefore, the stress-induced coronary vasodilation resulted from NO overproduction by both iNOS and eNOS. NOS induction was apparently due to systemic inflammation as evidenced by increased serum interleukin-1β and C-reactive protein in PTSD rats. Decreased corticosterone in PTSD rats may have contributed to inflammation and its effect on coronary tone. PTSD was also associated with voltage-gated K channel dysfunction, which would have also reduced coronary tone. [ABSTRACT FROM AUTHOR]