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Abstract Methyl protodioscin (MPD) is reported to relieve angina pectoris and myocardial ischemia, and mitochondrial E3 ubiquitin ligase 1 (Mul1) plays a key role in maintaining mitochondrial functions. Bioinformatic analysis shows potential interactions between MPD and Mul1. This study aims to explore whether MPD could protect rat brain against ischemia/reperfusion (I/R) injury through regulation of Mul1/ superoxide dismutase 2 (SOD2) pathway. The SD rat brains were subjected to 2 h of ischemia following by 24 h of reperfusion, which showed I/R injury (increase in neurological deficit score and infarct volume), up-regulation of Mul1 and down regulation of SOD2, these phenomena were attenuated by MPD treatment (3 or 10 mg/kg, i.g.). Consistently, in cultured HT22 cells, hypoxia-reoxygenation (H/R) treatment induced cellular injury (apoptosis and LDH release) concomitant with up-regulation of Mul1 and down regulation of SOD2, these phenomena were blocked in the presence of MPD (5 μM). Knockdown of Mul1 could also decrease SOD2 protein levels in HT22 cells accompanied by alleviation of H/R injury (reduction of apoptosis and LDH release). In agreement with the change of SOD2, reactive oxygen species generation was increased in H/R-treated HT22 cells while decreased in the presence of MPD. Based on these observations, we conclude that upregulation of Mul1 in rat brain contributes to cerebral I/R injury via suppression of SOD2 and that MPD protects rat brain from I/R injury through a mechanism involving regulation of Mul1/SOD2 pathway. Graphical abstract fx1 [ABSTRACT FROM AUTHOR]

Renal ischemia-reperfusion injury (I/RI) remains a critical clinical situation. Several evidence revealed the potential reno-protective effects of Vitamin D and/or pioglitazone, on renal I/RI. This study addresses the possible involvement of the Wnt4/β-catenin signaling, p -S536NF-κBp65, PPARγ, Ang II/TGF-β, and ACE2 as potential effectors to vitamin D and pioglitazone-mediated renoprotective effects. Two sets of Sprague-Dawley rats (n = 30 rat each), were randomized into sham, I/R, Vit D "alfacalcidol" (5 ng/kg/day), pioglitazone (5 mg/kg/day), and Vit D + pioglitazone groups. In all groups renal biochemical parameters, as well as inflammatory and structural profiles were assessed, besides the expression/contents of Wnt4/β-catenin and p S536-NF-κBp65. All treatments started 7 days before I/RI and animals were killed 24 h after I/RI in the first set, while those in the 2nd set continued their treatments for 14 days. After 24 h, all pre-treatments impeded theI/R effect on neutrophils recruitment, p -S536NF-κBp65, IL-18, NGAL, caspase-3, AngII, ACE-2, PPARγ and TGF-β, besides the expression of Wnt4 and ACE-2 with notable reflection on histological changes. Two weeks after I/RI, except a marked up regulation in Wnt4 expression and a striking elevation in the β-catenin content, the magnitude of the injurious events was relatively less pronounced, an effect that was mostly augmented by the different treatments. The current study pledges a promising and novel reno-protective role of the administration of Vit D and pioglitazone entailing a potential involvement of ICAM-1, MPO, NF-κB, Ang II, ACE2, TGFβ, and a modulation of Wnt4/β-catenin pathway. [ABSTRACT FROM AUTHOR]

The present study was designed to examine the protection of D-β-hydroxybutyrate (BHB) against ischemia/reperfusion (I/R) injury in heart and investigate its underlying mechanism. Male adult mice were exposed to 30 min of ischemia and 24 h of reperfusion. Osmotic pumps were implanted subcutaneously 5 min before reperfusion for continuous delivery of the exogenous BHB (1.6 mmol/kg/24 h). Treatment with BHB reduced infarct size and levels of cardiac troponin I, creatine kinase and lactate dehydrogenase in serum, attenuated apoptosis in myocardium, and preserved cardiac function of I/R mice. Importantly, treatment of I/R mice with BHB promoted autophagic flux, evidenced by reduced the ratio of LC3-II/LC3-I and protein expression of p62 and enhanced protein expression of lysosome associated membrane protein-2 (Lamp2) in myocardium. Treatment of I/R mice with BHB reduced mitochondrial formation of reactive oxygen species, enhanced adenosine triphosphate production, attenuated mitochondrial swelling, and partly restored mitochondrial membrane potential in myocardium. Furthermore, treatment of I/R mice with BHB abated oxidative stress and attenuated endoplasmic reticulum stress in myocardium. Our results indicated that treatment with exogenous BHB protected heart from I/R injury in mice. [ABSTRACT FROM AUTHOR]

Fasudil is a potent Rho-kinase (ROCK) inhibitor and can relax smooth muscle or cardiac muscle contraction through decreasing the phosphorylation level of myosin regulatory light chain (p-MLC 20 or p-MLC2v), while p-MLC2v can function as a transcription factor to promote the NADPH oxidase 2 (NOX2) expression in rat hearts subjected to ischemia/reperfusion (I/R). This study aims to explore whether fasudil can protect the rat hearts against I/R oxidative injury through suppressing NOX2 expression via reduction of p-MLC2v level. The SD rat hearts were subjected to 1 h-ischemia plus 3 h-reperfusion, which showed myocardial injuries (myocardial fiber loss and disarray, increase of creatine kinase release and myocardial infarction/apoptosis), increase in ROCK activity and nuclear p-MLC 2v level concomitant with up-regulation of NOX2 and H 2 O 2 production; these phenomena were attenuated by fasudil in a dose-dependent manner. Next, we verified the cardioprotective effect of fasudil and the underlying mechanisms in hypoxia-reoxygenation (H/R) -treated H9c2 cells. Consistent with the results in vivo, the H/R-treated H9c2 cells showed cellular injury (increase in apoptotic ratio), elevation in ROCK activity and nuclear p-MLC 2v level, accompanied by up-regulation of NOX2 and H 2 O 2 production; these effects were blocked in the presence of fasudil in a dose-dependent way. Based on these observations, we conclude that beneficial effect of fasudil against myocardial I/R or H/R oxidative injury is related to the suppression of NOX2 expression through decrease of the p-MLC2v level. Our findings also highlight that intervention of MLC2v phosphorylation by drugs may provide a novel strategy to protect heart from I/R oxidative injury. [ABSTRACT FROM AUTHOR]

Salidroside (Sal) is a natural antioxidant that elicits cardioprotective and neuroprotective effects in vivo and in vitro; however, its impact on hepatic ischemia/reperfusion (I/R) injury remains unclear. The purpose of this study was to investigate the hepatoprotective effects of salidroside against segmental (70%) warm hepatic I/R injury in rats. Animals were randomized into Sham, Sham+salidroside pretreatment (Sal), Sham+Sal+carboxyatractyloside (CATR), Sham+CATR, I/R, I/R+Sal, I/R+Sal+CATR and I/R+CATR groups. The hepatic artery, left portal vein and median liver lobes were occluded for 60 min and then unclamped to allow reperfusion. Pretreatment with salidroside (20 mg/kg/day for 7 days, intraperitoneally) significantly decreased serum alanine aminotransferase (sALT) and serum aspartate aminotransferase (sAST) levels after 6 h and 24 h of reperfusion and protected the liver against I/R-induced injury. However, this protective effect could be reversed by CATR, a mitochondrial permeability transition pore (MPTP) opener (5 mg/kg 30 min before I/R insult, intraperitoneally). Mechanistic studies have revealed that salidroside inhibits glycogen synthase kinase-3 beta (GSK-3β) activity and enhances the NF-E2-related factor (Nrf2)-dependent antioxidant response by activating the Akt signaling pathway, thereby reducing mitochondrial reactive oxygen species generation, increasing MPTP resistance and preventing apoptosis by suppressing cytochrome c release and caspase activation during reperfusion. Therefore, salidroside ameliorates hepatocyte death and apoptosis through activation of the GSK-3β/Nrf2-dependent antioxidant response and subsequent MPTP inhibition. These results provide experimental evidence supporting the clinical use of salidroside for hepatoprotection in surgical settings. [ABSTRACT FROM AUTHOR]

Ca 2+ -handling disturbances play an important role in the genesis of myocardial ischemia/reperfusion (I/R) injury. Ischemic preconditioning (IPC) is a powerful strategy to induce tolerance against subsequent ischemic episodes. IPC signaling pathways may be triggered by Ca 2+ ion. Since Na + /Ca 2+ exchanger 1 (NCX1) participates in modulating intracellular Ca 2+ homeostasis, here we further defined its role in I/R and investigated its potential involvement in IPC-induced cardioprotection. In isolated ventricular cardiomyocytes, perfused rat heart and H9c2 cardiomyoblasts, I/R produced a significant cell injury, assessed by measuring extracellular lactate dehydrogenase (LDH) and, for the whole heart, also by estimating myocardial infarct size area. Characterization of cell death revealed the involvement of apoptotic processes. Interestingly, I/R challenge induced NCX1 protein upregulation. In NCX1-transfected H9c2 cells, exchanger protein upregulation was accompanied by an increase in its reverse mode activity. The effects of I/R on extracellular LDH and infarct size area were drastically reduced by 1 μM SN-6, a selective NCX1 inhibitor. Moreover, SN-6 also prevented I/R-induced increase of NCX1 reverse-mode activity and protein upregulation. These results suggested a deleterious role of NCX1 in I/R-induced cell damage. In both isolated cardiomyocytes and perfused heart, IPC followed by I/R afforded cardioprotection, reducing extracellular LDH release and limiting ischemic area extent. Interestingly, NCX1 blockade (1 μM SN-6) completely abolished IPC protection against I/R, leading to exacerbation of cell injury, massive infarct size area and restoration of NCX1 protein expression. These findings suggest that NCX1 is deleterious in I/R, whereas it may be beneficial in promoting IPC-induced cardioprotection. [ABSTRACT FROM AUTHOR]

Aim of this study was to investigate the involvement of the mitochondrial permeability transition pore (MPTP) and oxidative stress in the cardioprotective effect of vasopressin (AVP) on ischemia/reperfusion (I/R) injury. Anesthetized male wistar rats were subjected to regional 30 min ischemia and 120 min reperfusion and randomly divided into nine groups: (1) Control; saline was administered intravenously before ischemia, (2) vasopressin was administrated 10 min prior to ischemia, (3, 4) Atractyloside as MPTP opener, was injected 5 min prior to reperfusion without and with vasopressin, (5, 6) Cyclosporine A as a MPTP closer, was injected 5 min prior to reperfusion without and with vasopressin, (7) mitochondria were isolated from control group and CaCl 2 was added as MPTP opener and swelling inducer, (8) isolated mitochondria from Control hearts was incubated with Cyclosporine A before adding the CaCl 2 (9) CaCl 2 was added to isolated mitochondria from vasopressin group. Infusion of vasopressin decreased infarct size (18.6±1.7% vs. control group 37.6±2.4%), biochemical parameters [LDH (Lactate Dehydrogenase), CK-MB (Creatine Kinase-MB) and MDA (Malondialdehyde) plasma levels, PAB (Prooxidant–antioxidant balance)] compared to control group. Atactyloside suppressed the cardioprotective effect of vasopressin (32.5±1.9% vs. 18.6±1.7%) but administration of the Cyclosporine A without and with vasopressin significantly reduced infarct size to 17.7±4% ( P <0.001) and 22.7±3% ( P <0.01) respectively, vs. 37.6±2.4% in control group. Also, vasopressin, similar to Cyclosporine A, led to decrease in CaCl 2 -induced swelling. It seems that vasopressin through antioxidant effect and MPTP inhibition has created a cardioprotection against ischemia/reperfusion injuries. [ABSTRACT FROM AUTHOR]

Obestatin, as ghrelin, has been originally extracted from the stomach, which remains its major source. Previous studies have shown that administration of obestatin exhibits protective and healing-promoting effects in several organs, including the stomach and kidney. In pancreas, pretreatment with obestatin inhibits the development of cerulein-induced acute pancreatitis and promotes survival of pancreatic beta cells and human islets. The aim of the present study was to check the universality of protective effect of obestatin in the pancreas. For this reason we investigated the influence of obestatin administration on the development of ischemia/reperfusion-induced pancreatitis. Acute pancreatitis was induced by pancreatic ischemia followed by reperfusion of the gland. Obestatin (4, 8 or 16 nmol/kg/dose) was administered intraperitoneally twice: 0.5 h before exposure to ischemia, and 3 h after the first injection. The effect of obestatin on the course of necrotizing pancreatitis was assessed after 6-h reperfusion, and included histological, functional, and biochemical analyses. Treatment with obestatin reduced morphological signs of pancreatic damage including edema, vacuolization of acinar cells, hemorrhages, acinar necrosis, and leukocyte infiltration of the gland. These effects were accompanied by an improvement of pancreatic DNA synthesis and superoxide dismutase activity, and a decrease in serum level of lipase and pro-inflammatory interleukin-1β. Moreover pretreatment with obestatin reduced myeloperoxidase activity and malondialdehyde concentration in pancreatic tissue of rats with acute pancreatitis. Conclusions : Administration of obestatin inhibits the development of ischemia/reperfusion-induced acute pancreatitis. This observation, taken together with previous findings that obestatin protects the pancreas against cerulein-induced pancreatitis, indicates that protective effect of obestatin in the pancreas is universal and independent of the primary cause of acute pancreatitis. [ABSTRACT FROM AUTHOR]

Nitric oxide (NO) and glutamate, via N-methyl- d -aspartate (NMDA) receptors, participate to changes in neuromuscular responses after ischemic/reperfusion (I/R) injury in the gut. In the present study we investigated the existence of a possible interplay between nitrergic and NMDA receptor pathways in the guinea pig ileum after in vitro I/R injury, resorting to functional and biomolecular approaches. In normal metabolic conditions NMDA concentration-dependently enhanced both glutamate (analyzed by high performance liquid chromatography with fluorimetric detection) and NO (spectrophotometrically quantified as NO 2 − and NO 3 − ) spontaneous overflow from isolated ileal segments. Both effects were reduced by the NMDA antagonists, (-)-AP5 (10 µM) and 5,7-diCl-kynurenic acid (10 µM, 5,7-diCl-KYN). N ω -propyl- l -arginine (1 µM, NPLA) and 1400W (10 µM), respectively, nNOS and iNOS inhibitors, reduced NMDA-stimulated glutamate overflow. After in vitro I/R, glutamate overflow increased, and returned to control values in the presence of NPLA and 1400W. NO 2 − and NO 3 − levels transiently increased during I/R and were reduced by both (-)-AP5 and 5,7-diCl-KYN. In longitudinal muscle myenteric plexus preparations, iNOS mRNA and protein levels increased after in vitro I/R; both parameters were reduced to control values by (-)-AP5 and 5,7-diCl-KYN. Both antagonists were also able to reduce ischemia-induced enhancement of nNOS mRNA levels. Protein levels of GluN1, the ubiquitary subunit of NMDA receptors, increased after I/R and were reduced by both NPLA and 1400W. On the whole, this data suggests the existence of a cross-talk between NMDA receptor and nitrergic pathways in guinea pig ileum myenteric plexus, which may participate to neuronal rearrangements occurring during I/R. [ABSTRACT FROM AUTHOR]

In this study we evaluated the effects of selective Na + /Ca 2+ exchanger (NCX) inhibition by ORM-10103 on the [Ca 2+ ] i transient (CaT), action potential (AP), and cell viability in isolated canine ventricular cardiomyocytes exposed to a simulated ischemia/reperfusion protocol performed either alone (modeling moderate low-flow ischemia) or with simultaneous strophantidine challenge (modeling more severe low-flow ischemia). CaTs were monitored using a Ca 2+ -sensitive fluorescent dye, APs were recorded by intracellular microelectrodes, and anaerobic shifts in cellular metabolism were verified via monitoring native NADH fluorescence. Simulated ischemia increased the NADH fluorescence, reduced the amplitudes of the AP and CaT and induced membrane depolarization. APs moderately shortened, CaTs prolonged. Diastolic [Ca 2+ ] i ([Ca 2+ ] iD ) level increased significantly during ischemia and further elevated following strophantidine application. Reperfusion normalized the NADH level, the amplitude of the AP and duration of the [Ca 2+ ] i transient, but only partially restored action potential triangulation and the amplitude of the CaT. [Ca 2+ ] iD decreased in untreated, but further increased in strophantidine-treated cells. 10 µM ORM-10103 significantly reduced the ischemic [Ca 2+ ] i raise in both untreated and strophantidine-treated cells. During reperfusion ORM-10103 decreased [Ca 2+ ] i and eliminated its diastolic elevation in untreated and strophantidine-treated cardiomyocytes. Following the application of ORM-10103 the detrimental effect of ischemia/reperfusion on cell viability and the reperfusion-induced increase in AP and CaT variabilities were substantially reduced, but ischemia-induced shifts in AP morphology were barely influenced. In conclusion, selective NCX inhibition by ORM-10103 is highly effective against ischemia/reperfusion induced pathologic alterations in [Ca 2+ ] i homeostasis, however, it fails to normalize untoward arrhythmogenic changes in AP morphology. [ABSTRACT FROM AUTHOR]

It has been recently proposed that repeated bladder ischemia/reperfusion induced by chronic pelvic ischemia may lead to detrusor overactivity, followed by lower urinary tract symptoms. Vibegron is a selective β 3 -adrenoceptor agonist approved for the treatment of overactive bladder. Several studies have tested β 3 -adrenoceptor agonists using animal models with detrusor overactivity related to bladder ischemia/reperfusion. However, whether β 3 -adrenoceptor agonists directly affect ischemia/reperfusion-evoked detrusor overactivity is unclear. Therefore, we examined whether bladder anoxia/reoxygenation could enhance spontaneous bladder contractions (SBCs) and investigated the effect of vibegron on enhanced SBCs. Isolated whole bladders from rats were incubated with Krebs solution aerated with 95% N 2 + 5% CO 2 for 5 h (anoxia). Subsequently, the bathing solution was replaced with an oxygen-saturated solution (reoxygenation). Anoxia/reoxygenation caused enhancement of the amplitude but not the frequency of SBC compared with that before reoxygenation. Vibegron (0.3–30 μM) inhibited this increase in SBC amplitude, but not the frequency, in a dose-dependent manner. The inhibitory effect of vibegron was not affected by pretreatment with the adenylyl cyclase inhibitor SQ22536 (100 μM) or protein kinase A inhibitor KT5720 (1 μM) and was not accompanied by considerable changes in cyclic adenosine monophosphate (cAMP) content in the bladder. In contrast, the large conductance potassium channel inhibitor iberiotoxin (100 nM) suppressed the inhibitory effect of vibegron. These results suggest that bladder ischemia/reperfusion induces SBC enhancement and vibegron directly inhibits detrusor overactivity via the large conductance potassium channel, which involves β 3 -adrenoceptor, rather than the cAMP signaling pathway. [ABSTRACT FROM AUTHOR]

Abstract: The small G protein RhoA and its downstream effector Rho-kinase play an important role in various physiopathological processes including ischemia/reperfusion (I/R) injury. Reactive oxygen and nitrogen species produced by iNOS and NADPH oxidase are important mediators of inflammation and organ injury following an initial localized I/R event. The aim of this study was to determine whether RhoA/Rho-kinase signaling pathway increases the expression and activity of MEK1, ERK1/2, iNOS, gp91phox, and p47phox, and peroxynitrite formation which result in oxidative/nitrosative stress and inflammation leading to hindlimb I/R-induced injury in kidney as a distant organ and gastrocnemius muscle as a target organ. I/R-induced distant and target organ injury was performed by using the rat hindlimb tourniquet model. I/R caused an increase in the expression and/or activity of RhoA, MEK1, ERK1/2, iNOS, gp91phox, p47phox, and 3-nitrotyrosine and nitrotyrosine levels in the tissues. Although Rho-kinase activity was increased by I/R in the kidney, its activity was decreased in the muscle. Serum and tissue MDA levels and MPO activity were increased following I/R. I/R also caused an increase in SOD and catalase activities associated with decreased GSH levels in the tissues. Y-27632, a selective Rho-kinase inhibitor, (100µg/kg, i.p.; 1h before reperfusion) prevented the I/R-induced changes except Rho-kinase activity in the muscle. These results suggest that activation of RhoA/Rho-kinase/MEK1/ERK1/2/iNOS pathway associated with oxidative/nitrosative stress and inflammation contributes to hindlimb I/R-induced distant organ injury in rats. It also seems that hindlimb I/R induces target organ injury via upregulation of RhoA/MEK1/ERK1/2/iNOS pathway associated with decreased Rho-kinase activity. [Copyright &y& Elsevier]

Abstract: Present study was undertaken to evaluate the protective effect of 1,2,3,4,6-penta-O-galloyl-β-d-glucopyranose (PGG) against transient global ischemia/reperfusion (I/R)-induced brain injury in rats. Sixty minutes of global ischemia, followed by 24h of reperfusion caused significant alterations in cognition and memory (p<0.01), significant deterioration of motor coordination, grip strength, and limb tone (P<0.01) associated with neurological deficit. In addition, significant decrease in catalase (P<0.01), and superoxide dismutase (SOD) (P<0.01) activities, increase in lipid peroxidation (P<0.01), depletion of reduced glutathione (GSH) (P<0.01), and increase in brain volume (P<0.01) was observed. Additionally, I/R insult has aggravated the cerebral infarct formation (P<0.01), and the histopathology of brain showed congestion of blood vessels, edema of brain parenchyma, leukocyte infiltration as signs of neuroinflammation, and necrosis of brain tissue. Interestingly, pre-treatment with quercetin (20mg/kg, i.p.), and PGG (5 and 10mg/kg, i.p.) for 7 days showed significant, and dose dependent protection against I/R-induced brain injury by alleviating all the behavioral, neurological, morphological, and histological changes induced by I/R. Besides, PGG is a well-known antioxidant, and its protective effect against I/R-induced brain injury is thought to be due to its potent antioxidant property. [Copyright &y& Elsevier]

Abstract: We have found that a series of brief renal ischemia and reperfusion (preconditioning), before the time of ischemia significantly attenuated the ischemia/reperfusion-induced acute kidney injury through endothelial nitric oxide synthase. In this study, we examined the effects of ischemic preconditioning on renal sympathetic nervous system and kidney function in ischemia/reperfusion-induced acute kidney injury with or without nitric oxide synthase inhibitor. Ischemia/reperfusion-induced acute kidney injury was made by clamping the left renal artery and vein for 45-min followed by reperfusion, 2 weeks after the contralateral nephrectomy. Ischemic preconditioning, consisting of three cycles of 2-min ischemia followed by 5-min reperfusion, was performed before the 45-min ischemia. Ischemic preconditioning suppressed the enhanced renal sympathetic nerve activity during ischemia and the elevated renal venous plasma norepinephrine level after reperfusion, and attenuated renal dysfunction and histological damage. The renoprotective effect of ischemic preconditioning was diminished by NG-nitro-L-arginine methyl ester (0.3mg/kg, i.v.), a nonselective nitric oxide synthase inhibitor, 5min before the start of ischemic preconditioning. Thus, ischemic preconditioning decreased renal sympathetic nerve activity and norepinephrine release probably through activating nitric oxide production, thereby improving ischemia/reperfusion-induced acute kidney injury. [Copyright &y& Elsevier]

Abstract: Enhancement of renal sympathetic nerve activity during renal ischemia and norepinephrine overflow from the kidney after reperfusion play important roles in the development of ischemic acute kidney injury. Recently, we have found that moxonidine, an α2/imidazoline Ι1-receptor agonist, has preventive effects on ischemic acute kidney injury by suppressing the excitation of renal sympathetic nervous system after reperfusion. In the present study, to clarify the renoprotective mechanisms of moxonidine (360nmol/kg, i.v.) against ischemic acute kidney injury, we investigated the effect of intravenous (i.v.) and intracerebroventricular (i.c.v.) injection of efaroxan, an α2/Ι1 receptor antagonist, on the moxonidine-exhibited actions. Ischemic acute kidney injury was induced by clamping the left renal artery and vein for 45min followed by reperfusion, 2 weeks after contralateral nephrectomy. The suppressive effect of moxonidine on enhanced renal sympathetic nerve activity during renal ischemia was not observed in the rat treated with either i.v. (360nmol/kg) or i.c.v. (36nmol/kg) of efaroxan. Furthermore, i.v. injection of efaroxan eliminated the preventive effect of moxonidine on ischemia/reperfusion-induced kidney injury and norepinephrine overflow, and i.c.v. injection of efaroxan did not completely inhibit the moxonidine's effects. These results indicate that moxonidine prevents the ischemic kidney injury by sympathoinhibitory effect probably via α2/Ι1 receptors in central nervous system and by suppressing the norepinephrine overflow through α2/Ι1 receptors on sympathetic nerve endings. [Copyright &y& Elsevier]

Abstract: The purpose of this study is to investigate the effects and the underlying mechanisms of sitagliptin pretreatment on myocardial injury and cardiac function in myocardial ischemia/reperfusion (I/R) rat model. The rat model of myocardial I/R was constructed by coronary occlusion. Rats were pretreated with sitagliptin (300mg/kg/day) for 2 weeks, and then subjected to 30min ischemia and 2h reperfusion. The release of lactate dehydrogenase (LDH) and creatine kinase-MB (CK-MB), cardiac function and cardiomyocyte apoptosis were evaluated. The levels of malondialdehyde (MDA), glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) in heart and glucagon-like peptide-1 (GLP-1) level in plasma were measured. Western blot analysis was performed to detect the target proteins of sitagliptin. Our results showed that sitagliptin pretreatment decreased LDH and CK-MB release, and MDA level in I/R rats. More importantly, we revealed for the first time that sitagliptin pretreatment decreased cardiomyocyte apoptosis while increased the levels of GSH-Px and SOD in heart. Sitagliptin also increased GLP-1 level and enhanced cardiac function in I/R rats. Furthermore, sitagliptin pretreatment up-regulated Aktserine473 and Badserine136 phosphorylation, reduced the ratio of Bax/Bcl-2, and decreased expression levels of cleaved caspase-3 and caspase-3. Interestingly, the above observed effects of sitagliptin were all abolished when co-administered with GLP-1 receptor antagonist exendin-(9-39) or PI3K inhibitor LY294002. Taken together, our data indicate that sitagliptin pretreatment could reduce myocardial injury and improve cardiac function in I/R rats by reducing apoptosis and oxidative damage. The underlying mechanism might be the activation of PI3K/Akt signaling pathway by GLP-1/GLP-1 receptor. [Copyright &y& Elsevier]

Abstract: Resistance to ischemic acute kidney injury has been shown to be higher in female rats than in male rats. We found that renal venous norepinephrine overflow after reperfusion played important roles in the development of ischemic acute kidney injury. In the present study, we investigated whether sex differences in the pathogenesis of ischemic acute kidney injury were derived from the renal sympathetic nervous system using male and female Sprague-Dawley rats. Ischemia/reperfusion-induced acute kidney injury was achieved by clamping the left renal artery and vein for 45min followed by reperfusion, 2 weeks after contralateral nephrectomy. Renal function was impaired after reperfusion in both male and female rats; however, renal dysfunction and histological damage were more severe in male rats than in female rats. Renal venous plasma norepinephrine levels after reperfusion were markedly elevated in male rats, but were not in female rats. These sex differences were eliminated by ovariectomy or treatment with tamoxifen, an estrogen receptor antagonist, in female rats. Furthermore, an intravenous injection of hexamethonium (25mg/kg), a ganglionic blocker, 5min before ischemia suppressed the elevation in renal venous plasma norepinephrine levels after reperfusion, and attenuated renal dysfunction and histological damage in male rats, and ovariectomized and tamoxifen-treated female rats, but not in intact females. Thus, the present findings confirmed sex differences in the pathogenesis of ischemic acute kidney injury, and showed that the attenuation of ischemia/reperfusion-induced acute kidney injury observed in intact female rats may be dependent on depressing the renal sympathetic nervous system with endogenous estrogen. [Copyright &y& Elsevier]

Abstract: Hepatic ischemia/reperfusion (I/R) elicits an excessive inflammatory response, posing a lethal threat to the host. Local inflammation may be regulated by the vagus nerve and activation of the nicotinic acetylcholine receptors may also suppress peripheral inflammation. We have previously demonstrated that heme oxygenase-1 (HO-1) protects the liver against I/R injury by modulating proinflammatory mediators. Here, we investigate the cytoprotective mechanisms of nicotine, a nicotinic acetylcholine receptor agonist, against liver injury caused by I/R. Mice were subjected to 60min of ischemia followed by 3h of reperfusion. Nicotine (0.1, 0.3 and 1mg/kg) and vehicle (saline) were administered intraperitoneally 20min prior to ischemia. Serum alanine aminotransferase activity and lipid peroxidation levels increased after reperfusion, while total glutathione content decreased. These changes were markedly attenuated by nicotine. The levels of HO activity and HO-1 protein expression increased after reperfusion, and nicotine markedly augmented these increases. Serum levels of high mobility group box 1 and tumor necrosis factor-α increased after reperfusion, and nicotine prevented these increases. The nuclear translocation of NF-E2-related factor 2 and phosphorylation of both phosphatidyl inositol 3-kinase and Akt increased; nicotine also augmented these increases. The protein expression of nuclear factor-κB increased and nicotine attenuated this increase. Methyllycaconitine, a selective α7 nicotinic acetylcholine receptor antagonist, abolished these effects of nicotine. Furthermore, zinc protoporphyrin, an HO-1 inhibitor, also reversed the observed effects of nicotine. Our findings suggest that activation of α7 nicotinic acetylcholine receptor by nicotine ameliorates I/R-induced liver injury, and that this protection is likely due to inhibition of the inflammatory response through HO-1 induction. [Copyright &y& Elsevier]

Abstract: Myocardial apoptosis is primarily triggered during reperfusion. Various mechanisms are involved, including oxidative stress which activates the translocation of nuclear factor-kappa B (NF-κB) and stimulates the release of tumor necrosis factor-alpha (TNF-α). However, the relative contribution of the renin angiotensin system (RAS) to the development of myocardial apoptosis during reperfusion remains unknown. In the present study, we examined whether inhibition of RAS with Valsartan, an Angiotensin II 1 receptor (AT1) antagonist, could reduce apoptosis during reperfusion. We constructed a rat model of myocardial ischemia reperfusion injury. Rats were pretreated with Valsartan for 2 weeks, and then subjected to 30min ischemia and 4h reperfusion. Apoptosis was detected by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL). Levels of malondialdehyde (MDA), superoxide dismutase (SOD), TNF-α, and caspase-3 were detected by ELISA. NF-κB, Nicotinamide Adenine Dinucleotide Phosphate (NADPH) oxidase expression was assessed by Western blot analysis. Valsartan inhibited apoptosis (TUNEL staining) in ischemic myocardium (P<0.05), consistent with reduced caspase-3 activity. Valsartan also inhibited of NF-κB translocation to nucleus (P<0.05), and decreased plasma TNF-α levels (P<0.05). Valsartan pretreatment suppressed MDA content and preserved SOD activity, consistent with reduced NADPH oxidase expression (P<0.01). These data provided substantial evidence that RAS was involved in NF-κB activation, mediated by AT1 dependent oxidative stress; thus, RAS might ultimately promote myocardial apoptosis during reperfusion pathogenesis. [Copyright &y& Elsevier]

Abstract: Fatty livers occur in up to 20% of potential liver donors and increase cellular injury during the ischemia/reperfusion phase, so any intervention that could enable a better outcome of grafts for liver transplantation would be very useful. The effect of melatonin on liver ischemia/reperfusion injury in a rat model of obesity and hepatic steatosis has been investigated. Forty fa/fa Zucker rats were divided in 4 groups. 3 groups were subjected to 35min of warm hepatic ischemia and 36h of reperfusion. One experimental group remained untreated and 2 were given 10mg/kg melatonin intraperitoneally or orally. Another group was sham-operated. Plasma ALT, AST and hepatic content of ATP, MDA, hydroxyalkenals, NOx metabolites, antioxidant enzyme activity, caspase-9 and DNA fragmentation were determined in the liver. The expression of iNOS, eNOS, Bcl2, Bax, Bad and AIF were determined by RT-PCR Melatonin was effective at decreasing liver injury by both ways as assessed by liver transaminases, markers of apoptosis, of oxidative stress and improved liver ATP content. Melatonin administration decreased the activities or levels of most of the parameters measured in a beneficial way, and our study identified also some of the mechanisms of protection. We conclude that administration of melatonin improved liver function, as well as markers of pro/antioxidant status and apoptosis following ischemia/reperfusion in obese rats with fatty liver. These data suggest that this substance could improve outcome in patients undergoing liver transplantation who receive a fatty liver implant and suggest the need of clinical trials with it in liver transplantation. [Copyright &y& Elsevier]

Abstract: The present study was undertaken to examine the effect of acute treatment with 17β-estradiol on post-ischemic cardiac dysfunction and norepinephrine overflow and its possible mechanisms. Male rat hearts were perfused with the Langendorff method and subjected to 40min of global ischemia followed by 30min of reperfusion. Each drug was perfused from 15min before ischemia to 5min after reperfusion. During reperfusion, 17β-estradiol treatment showed significantly greater functional recovery of left ventricular developed pressure (LVDP), left ventricular end diastolic pressure (LVEDP), and dP/dt max. Excessive norepinephrine release in coronary effluent from the post-ischemic heart was notably suppressed by treatment with 17β-estradiol. These beneficial effects of 17β-estradiol were not observed in the presence of the nitric oxide synthase inhibitor NG-nitro-l-arginine and estrogen receptor antagonist ICI 182,780 ((7α, 17β)-7-[9-[(4,4,5,5,5-pentafluoropentyl)sulfinyl]nonyl]estra-1,3,5(10)-triene-3,17-diol), respectively. When NO2/NO3 levels in coronary effluents after the onset of reperfusion were measured, reverse-correlation relationships between NO2/NO3 production and ischemia/reperfusion-induced cardiac dysfunction, as well as norepinephrine overflow were observed. These findings suggest that 17β-estradiol exerts cardioprotective effects against ischemia/reperfusion-induced cardiac dysfunction, at least in part, by suppressing norepinephrine overflow, and that nitric oxide production via estrogen receptor activation plays a key role in this process. [Copyright &y& Elsevier]

Abstract: Ample of evidence proved the gastroprotective effect of thymoquinone (TQ), the main constituent of Nigella sativa oil; however, the full mechanistic cassette on the gastric ulcer etiopathogenesis is not fully elucidated. The aim of the present work is to unveil some of the possible mechanisms. Animals were injected with vehicle, TQ (10 & 20mg/kg), omeprazole (10 & 20mg/kg) or their combination (10mg/kg). Thirty minutes later, pyloric ligation was carried out and followed consequently with ischemia for another 30min, abided by reperfusion for 120min. The ischemia/reperfusion insult increased the gastric acid secretion, acid output, and pepsin, as well as the gastric mucosal content/activity of lipid peroxide, proton pump and myeloperoxidase, along with ulcer index. However, content/activity of gastric mucin, reduced glutathione, total nitric oxide, and superoxide dismutase were decreased. TQ, especially the high dose level, corrected the altered parameters in a comparable manner to that of the reference drug used, omeprazole. In addition, when the low doses were combined they add to each other to reach the effect of the high dose of either drug. These results showed that apart from its known antioxidant properties, TQ has novel gastroprotective mechanisms via inhibiting proton pump, acid secretion and neutrophil infiltration, while enhancing mucin secretion, and nitric oxide production. [Copyright &y& Elsevier]

Abstract: Enhanced renal sympathetic nerve activity during an ischemic period and renal venous norepinephrine overflow after reperfusion play important roles in the development of ischemic acute kidney injury. In this study, we examined the effect of 17β-estradiol on the renal sympathetic nervous system and kidney function in ischemia/reperfusion-induced acute kidney injury in anesthetized rats. Ischemic acute kidney injury was induced by clamping the left renal artery and vein for 45min followed by reperfusion, 2weeks after a contralateral nephrectomy. Intravenous injection of 17β-estradiol (100μg/kg) 15min before reperfusion suppressed enhanced renal sympathetic nerve activity during renal ischemia, also suppressed renal venous norepinephrine overflow after reperfusion, and attenuated ischemia/reperfusion-induced renal dysfunction with histological damage. The above renoprotective effects of 17β-estradiol were reversed by pretreatment with tamoxifen (5mg/kg), an estrogen receptor antagonist, or NG-nitro-L-arginine methyl ester (0.3mg/kg), a non-selective nitric oxide synthase inhibitor. These results indicate that 17β-estradiol can suppress enhanced renal sympathetic nerve activity during renal ischemia, and its consequent effect on norepinephrine overflow from nerve endings, by nitric oxide production via estrogen receptors. These effects appear to contribute to renoprotection against ischemia/reperfusion-induced renal injury. [Copyright &y& Elsevier]

Abstract: Delayed graft function secondary to ischemia/reperfusion injury has been shown to be associated with increased rate of allograft failure following kidney transplantation. Previously, we have shown that chronic lithium pretreatment protects kidney against ischemia/reperfusion injury. In the present study we aimed to examine the effects of acute lithium administration on the renal ischemia/reperfusion injury in rat. Ischemia/reperfusion injury was induced by clamping left renal pedicle for 60min, two weeks after right nephrectomy. The mechanism of lithium-mediated renoprotection was explored by combined use of lithium and nitro-l-arginine methyl ester (L-NAME) (non-selective nitric oxide synthase inhibitor) and/or indomethacin (non-selective cyclooxygenase pathway inhibitor). Lithium-treated animals were given 40mg/kg lithium chloride intraperitoneally, 30min before ischemia. To investigate the role of nitric oxide and cyclooxygenase pathways in renoprotective effect of lithium, L-NAME and/or indomethacin were administered before lithium injection. Serum creatinine, blood urea nitrogen, and renal histology were assessed after 24h of reperfusion. Lithium preconditioning significantly reduced creatinine and blood urea nitrogen (P<0.001) and improved renal histology. Administration of L-NAME completely reversed renoprotective effect of lithium. In contrast indomethacin significantly potentiated the lithium renoprotection. Moreover, co-administration of L-NAME and indomethacin completely abolished the protective effects of lithium. The results show that a single dose of lithium significantly improves renal function following ischemia/reperfusion injury. In conclusion, the ability of lithium to enhance renal tissue tolerance against ischemia/reperfusion injury suggests a potential clinical application in the setting of kidney transplantation. However, more detailed investigations are required before any definite conclusion. [Copyright &y& Elsevier]

Abstract: The therapeutic potential of cannabidiol, the major non-psychotropic Cannabis constituent, was investigated in rats exposed to ischemia/reperfusion liver injury. Ischemia was induced by clamping the pedicle of the left hepatic lobe for 30min, and cannabidiol (5mg/kg, i.v.) was given 1h following the procedure and every 24h thereafter for 2days. Ischemia/reperfusion caused significant elevations of serum alanine aminotransferase and hepatic malondialdehyde, tumor necrosis factor-α and nitric oxide levels, associated with significant decrease in hepatic reduced glutathione. Cannabidiol significantly attenuated the deterioration in the measured biochemical parameters mediated by ischemia/reperfusion. Histopathological examination showed that cannabidiol ameliorated ischemia/reperfusion-induced liver damage. Immunohistochemical analysis revealed that cannabidiol significantly reduced the expression of inducible nitric oxide synthase, cyclooxygenase-2, nuclear factor-κB, Fas ligand and caspase-3, and increased the expression of survivin protein in ischemic/reperfused liver tissue. These results emphasize that cannabidiol represents a potential therapeutic option to protect the liver against hypoxia–reoxygenation injury. [Copyright &y& Elsevier]

Abstract: It has been demonstrated that conditioned medium from astrocytes challenged by in vitro ischemia (oxygen–glucose deprivation, OGD) improved neuronal survival. In addition, preconditioning stimuli can be cross-tolerant, safeguarding against other types of injury. We therefore hypothesized that hyperthermia-conditioned astrocyte-cultured medium (ACM) might also have protective effect on neurons against ischemic injury. The cultured-media, named 38ACM and 40ACM respectively, were collected after astrocytes had been incubated at 38°C or 40°C for 6h, followed by incubation at 37°C for 24h. It was found that ischemia for 6h induced a significant reduction in the number of neuronal cells and cell-viability, and an increase in lactate dehydrogenase (LDH) release and the percentage of apoptotic nuclei in neurons. Pre-treatment with 38ACM or 40ACM for 24h significantly diminished ischemia injury, enhanced cell viability, reduced LDH release and reversed apoptosis. Western blot analysis showed that treatment with 38ACM or 40ACM for 24h led to a significant increase in hypoxia-inducible factor-1 (HIF-1) alpha expression. The EMSA demonstrated that the ACM increased the binding activity of HIF-1 in ischemic neurons. The data implied that hyperthermia-conditioned ACM protects neurons from ischemic injury by up-regulating HIF-1 alpha, and the increased binding activity of HIF-1 and anti-apoptotic ability. [Copyright &y& Elsevier]

Abstract: Since H2S has an emerging role as a cardioprotector, we hypothesized that NaHS addition to the new cardioplegic histidine buffer solution (HBS) could improve its cardioprotective potential. Male Wistar–Han rat hearts were divided in 4 groups: i) control, ii) perfusion control (perfusion only), iii) 6h ischemia in HBS or in a modified-HBS with 100μM of NaHS, a H2S donor, (HBSM) and iv) as iii followed by 30min reperfusion. During ischemia, aliquots of the cardioplegic solution were collected for NMR analysis. Heart mitochondria respiration and transmembrane potential were measured after ischemia or after ischemia followed by reperfusion. Proteins involved in the apoptotic signaling pathway were also quantified in both mitochondrial and tissue samples. Cardiac mechanic performance was evaluated by measuring the heart rate and the left ventricular pressure. In HBSM-preserved hearts, a) glucose consumption increased as well as lactate and alanine production during ischemia, b) heart mitochondria presented an improved phosphorylative efficiency, including decreased phosphorylative lag phase for complex I and complex II substrates, c) mitochondrial and tissue p53, Bax and caspase-9 were lower and d) there was a more positive atrial chronotropic response than in HBS-preserved hearts. We concluded that the addition of NaHS to HBS enhances glycolysis during ischemia, decreases mitochondrial dysfunction, especially by preserving the phosphorylative system, prevents apoptosis and during ischemia/reperfusion. [ABSTRACT FROM AUTHOR]

Abstract: We investigated the effects of the hydrogen sulfide (H2S)-releasing derivatives of aspirin (ACS14) and salicylic acid (ACS21) in a rat model of metabolic syndrome induced by glutathione (GSH) depletion, causing hypertension and other pathological cardiovascular alterations. GSH depletion was induced in normal rats by the GSH-synthase inhibitor buthionine sulfoximine (BSO, 30mmol/L day for seven days in the drinking water). Systolic blood pressure and heart rate were measured daily by the tail-cuff method, and plasma thromboxane B2, 6-keto-prostaglandin F2α, 8-isoprostane, GSH, insulin and glucose were determined at the end of the seven-day BSO schedule. In addition, ischemia/reperfusion-induced myocardial dysfunction and endothelial dysfunction were assayed on isolated heart and aortic rings, respectively. Unlike aspirin and salicylic acid, ACS14 and ACS21 reduced BSO-induced hypertension, also lowering plasma levels of thromboxane B2, 8-isoprostane and insulin, while GSH remained in the control range. Neither ACS14 nor ACS21 caused gastric lesions. Both restored the endothelial dysfunction observed in aortic rings from BSO-treated rats, and in ischemia/reperfusion experiments they lowered left ventricular end-diastolic pressure, consequently improving the developed pressure and the maximum rise and fall of left ventricular pressure. Together with this improvement of heart mechanics there were reductions in the activity of creatine kinase and lactate dehydrogenase in the cardiac perfusate. This implies that H2S released by both ACS14 and ACS21 was involved in protecting the heart from ischemia/reperfusion, and significantly limited vascular endothelial dysfunction in aortic tissue and the related hypertension. [ABSTRACT FROM AUTHOR]

Abstract: Ischemia/reperfusion injury is a major problem in renal transplantation. Several evidences represent lithium preconditioning effect against ischemia/reperfusion injury in various tissues. In this study our aim was to investigate the protective effect of chronic lithium administration on renal ischemia/reperfusion injury in rats. Ischemia/reperfusion injury was induced by clamping left renal pedicle for 60min, 2weeks after right nephrectomy. Lithium-treated animals received lithium-chloride in drinking water for 30days. In order to investigate the role of nitric oxide (NO) and cyclooxygenase (COX) pathways in renoprotective effect of lithium, N ω-nitro-L-arginine methyl ester hydrochloride (L-NAME, NO synthase inhibitor) and indomethacin (COX inhibitor) were used, respectively. Serum creatinine, blood urea nitrogen and renal histology were assessed 24h after inducing ischemia/reperfusion injury. Dimercaptosuccinic acid scan was also performed 48h following operation. Chronic lithium treatment in ischemia/reperfusion injury groups significantly decreased creatinine (1.09±0.16mg/dl), blood urea nitrogen (59.0±13.38mg/dl), histological damage (7.83%±4.02%) and improved cortical function compared with non-lithium treated animals (4.45±0.44, 176.66±12.24mg/dl and 83.5%±3.5%, respectively) (P<0.001). Either L-NAME or indomethacin administration partially reversed the protective effect of lithium, while simultaneous blockade of NO and COX pathways completely abolished lithium renoprotective effect. Our results indicate that lithium ameliorates renal ischemia/reperfusion injury through NO and/or COX pathways. We propose that lithium pre-treatment as a simple and practical intervention to boost the renal viability and function after ischemia/reperfusion injury may be promising in the setting of transplantation. [ABSTRACT FROM AUTHOR]

Abstract: Enhanced renal sympathetic nerve activity during ischemic period and the renal venous norepinephrine overflow after reperfusion play important roles in the development of ischemic acute kidney injury. We investigated the effect of γ-aminobutyric acid (GABA), an inhibitory neurotransmitter mainly in the central nervous system, on ischemia/reperfusion-induced acute kidney injury in anesthetized rats. Ischemic acute kidney injury was induced by clamping the left renal artery and vein for 45min followed by reperfusion 2weeks after the contralateral nephrectomy. Intravenous injection of GABA (10 and 50μmol/kg) to ischemic acute kidney injury rats dose-dependently suppressed the enhanced renal sympathetic nerve activity during the renal ischemia, the renal venous norepinephrine overflow after reperfusion and attenuated the ischemia/reperfusion-induced renal dysfunction with histological damage. Intravenous injection of CGP52432 (0.1μmol/kg), a selective GABAB receptor antagonist, eliminated the preventive effect by GABA (50μmol/kg) on ischemic acute kidney injury. In contrast, intravenous injection of baclofen (1μmol/kg), a selective GABAB receptor agonist, attenuated the ischemia/reperfusion-induced renal injury equivalent to GABA (50μmol/kg). These results indicate that GABA prevents the development of ischemia/reperfusion-induced acute kidney injury presumably via GABAB receptor, by suppressing the enhanced renal sympathetic nerve activity during ischemia and the increased norepinephrine overflow from renal sympathetic nerve ending. [Copyright &y& Elsevier]

Abstract: Intestinal ischemia/reperfusion causes severe injury and alters motility. N-methyl-d-aspartate (NMDA) receptor antagonists have been shown to reduce ischemia/reperfusion injury in the nervous system, and in other organs. In this study, we set out to investigate the effects of NMDA receptor antagonists over intestinal ischemia/reperfusion injury. Male Wistar rats were randomly divided into four groups: (1) a control, sham-operated group; (2) an intestinal ischemia/reperfusion group subjected to 45min ischemia and 1h reperfusion; (3) a group treated with 10mg/kg ketamine before ischemia/reperfusion; and (4) a group treated with 10mg/kg memantine before ischemia/reperfusion. Intestinal samples were taken for histological evaluation. Serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), malondialdehyde (MDA), total antioxidant capacity, tumor necrosis factor alpha (TNF-alpha), P-selectin and antithrombin III (ATIII) were measured. Intestinal transit time was determined to evaluate intestinal motility. Fecal pellet output and animal weight were also registered daily for 7days post-ischemia. After reperfusion, AST, LDH, TNF-alpha and P-selectin levels were elevated, ATIII levels were depleted, and ALT levels were unchanged in serum. Additionally, levels of MDA were increased and total antioxidant capacity was reduced in serum, indicating oxidative stress. Intestinal mucosa showed severe injury. Ketamine, but not memantine, diminished these alterations. Intestinal motility and fecal pellet output were also altered after ischemia/reperfusion. Both drugs abolished the alterations in motility. In conclusion, ketamine''s protective effects over ischemia/reperfusion do not appear to be NMDA mediated, but they could be playing a role in protecting the intestine against ischemia-induced functional changes. [Copyright &y& Elsevier]

Abstract: The pathogenesis of gastric mucosal injury is a multifaceted process involving reactive oxygen and nitrogen species, both of which play a crucial role in the ischemia/reperfusion model of gastric damage. Hence, several studies have evaluated the anti-ulcerogenic effect of metal chelators, antioxidative enzymes, and low-molecular-weight antioxidants. Low molecular weight superoxide dismutase (SOD) mimetics have been shown to play a protective role against oxidative damage. Therefore, the aim of the current study was to investigate the modulatory effect of 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl [TEMPOL (50 mg/kg)], a SOD mimetic, and the SOD inhibitor, diethyldithiocarbamate [DETCA (100 mg/kg)] on gastric lesions induced by ischemia/reperfusion. This insult produced typical gastric lesions, a significant fall in the gastric mucosal glutathione (GSH) and nitric oxide (NO) levels, accompanied by an increase in malondialdehyde (MDA) content and myeloperoxidase (MPO) activity. TEMPOL markedly minimized gastric ulceration and restored MDA, NO, and MPO levels, but did not alter GSH level, which dropped drastically in DETCA treated group, an effect that was not reflected on gross lesions induced by ischemia/reperfusion. In conclusion, TEMPOL can confer protection from gastric ischemia/reperfusion injury possibly by reducing the level of superoxide anion (O2 •−), replenishing NO, and minimizing neutrophil infiltration. Therefore, specific SOD mimetics could be beneficial as complementary agents in the management of gastric ulceration. [Copyright &y& Elsevier]

Abstract: Enhancement of renal sympathetic nerve activity during renal ischemia and its consequent effect on norepinephrine overflow from nerve endings after reperfusion play important roles in the development of ischemic acute kidney injury. In the present study, we evaluated whether moxonidine, an α2-adrenaline/I1-imidazoline receptor agonist which is known to elicit sympathoinhibitory action, would prevent the post-ischemic renal injury. Ischemic acute kidney injury was induced by clamping the left renal artery and vein for 45 min followed by reperfusion, 2 weeks after contralateral nephrectomy. Intravenous (i.v.) injection of moxonidine at a dose of 360 nmol/kg to ischemic acute kidney injury rats suppressed the enhanced renal sympathetic nerve activity during the ischemic period, to a degree similar to findings with intracerebroventricular (i.c.v.) injection of moxonidine at a dose of 36 nmol/kg. On the other hand, suppressive effects of the i.v. treatment on renal venous norepinephrine overflow, renal dysfunction and tissue injury in the post-ischemic kidney were significantly greater than those elicited by the i.c.v. treatment. These results suggest that renoprotective effects of moxonidine on ischemic acute kidney injury probably result from its suppressive action on the ischemia-enhanced renal sympathetic nerve activity followed by norepinephrine spillover from the nerve endings of the post-ischemic kidney. [Copyright &y& Elsevier]

Abstract: Lithium is widely used for the management of neuropsychiatric symptoms in bipolar disorders. A variety of hypotheses have been invoked to explain the mechanism of action of lithium. To determine if lithium exerts direct cardiac protection, in the present study perfused rat heart model was used. The mechanism of lithium-mediated cardioprotection was explored by combined use of lithium and nitro-l-arginine methyl ester (L-NAME, a non-selective nitric oxide synthase inhibitor) or indomethacin (a non-selective cyclooxygenase pathway inhibitor). Rat isolated hearts were used for Langendorff perfusion. Hearts were either non-preconditioned or preconditioned with acute lithium (3 mM) or chronic lithium (600 mg/l in tap water for 4 weeks, 0.265±0.023 mM in serum) before 30 min global ischemia followed by 90 min reperfusion. Within each of these protocols, hearts were divided into two groups; one group was exposed to L-NAME (0.1 mM) and another group was exposed to indomethacin (10 µM). Infarct size was measured by the triphenyltetrazolium chloride method. Left ventricular function was assessed by left ventricular developed pressure (LVDP), heart rate and coronary flow (CF). In our experiment acute and/or chronic administration of lithium before prolonged ischemia offered significant myoprotective effects in terms of infarct size reduction and improved cardiac function against ischemia/reperfusion injury. The effects of lithium pretreatment were prevented by the administration of indomethacin but not L-NAME. In conclusion, our results demonstrate that preconditioning with acute and/or chronic lithium administration improves recovery of the ventricular function and reduces infarct size via cyclooxygenase (COX) pathway in isolated rat heart. [Copyright &y& Elsevier]

Abstract: Endothelin-1 and norepinephrine are involved in myocardial ischemia/reperfusion injury. The aim of this study was to investigate the role of endogenously generated endothelin-1 in ischemia/reperfusion-induced norepinephrine overflow and cardiac dysfunction using a nonselective prototype of endothelin-converting enzyme (ECE) inhibitor, phosphoramidon, and a selective ECE inhibitor, SM-19712 (4-chloro-N-[[(4-cyano-3-methyl-1-phenyl-1H-pyrazol-5-yl)amino]carbonyl]benzenesulfonamide, monosodium salt). According to the Langendorff technique, isolated Sprague–Dawley rat hearts were subjected to 40-min global ischemia followed by 30-min reperfusion. Phosphoramidon and SM-19712 were perfused 30 min before ischemia and during reperfusion. Endothelin-1 level in left ventricle was increased by ischemia/reperfusion. This increase in left ventricular endothelin-1 level was suppressed by treatment with SM-19712. SM-19712 significantly improved ischemia/reperfusion-induced cardiac dysfunction such as decreased left ventricular developed pressure and dP/dtmax and increased left ventricular end diastolic pressure. In addition, this agent suppressed excessive norepinephrine overflow in the coronary effluent from the post-ischemic heart. In contrast, treatment with phosphoramidon further enhanced left ventricular endothelin-1 level and norepinephrine overflow, and significantly worsened cardiac dysfunction after ischemia/reperfusion. These responses such as exaggerated norepinephrine overflow and the cardiac dysfunction observed after ischemia/reperfusion were markedly suppressed in the presence of a selective endothelin ETA receptor antagonist, ABT-627 [2R-(4-methoxyphenyl)-4S-(1,3-benzodioxol-5-yl)-1-(N,N-di(n-butyl)aminocarbonyl-methyl)-pyrrolidine-3R-carboxylic acid]. These findings indicate that cardiac endothelin-1 production is enhanced by ischemia/reperfusion, and this endogenously increased endothelin-1 is involved in post-ischemic norepinephrine overflow and cardiac dysfunction via the activation of endothelin ETA receptors. [Copyright &y& Elsevier]

Abstract: Persistent Nuclear Factor-κB (NF-κB) activation is hypothesized to contribute to myocardial injuries following ischemia–reperfusion. Because inhibition or control of NF-κB signaling in the heart probably confers cardioprotection, we determined the potency of the NF-κB inhibitor dimethyl fumarate (DMF) in cardiovascular cells, and determined whether administration of DMF translates into beneficial effects in an animal model of myocardial infarction. In rat heart endothelial cells (RHEC), we analysed inhibitory effects of DMF on NF-κB using shift assay and immunohistofluorescence. In in vivo experiments, male Sprague Dawley rats undergoing left coronary artery occlusion for 45 min received either DMF (10 mg/kg body weight) or vehicle 90 min before ischemia as well as immediately before ischemia. After 120 min of reperfusion, the hearts were stained with phthalocyanine blue dye and triphenyltetrazolium chloride. Additionally, acute hemodynamic and electrophysiologic effects of DMF were determined in dose–response experiments in isolated perfused rat hearts. DMF inhibited TNF-α-induced nuclear entry of NF-κB in RHEC. In in vivo experiments, myocardial infarct size was significantly smaller in rats that had received DMF (20.7%±9.7% in % of risk area; n =17) than in control rats (28.2%±6.2%; n =15). Dose–response experiments in isolated perfused rat hearts excluded acute hemodynamic or electrophysiologic effects as mechanisms for the effects of DMF. DMF inhibits nuclear entry of NF-κB in RHEC and reduces myocardial infarct size after ischemia and reperfusion in rats in vivo. There was no indication that the beneficial effects of DMF were due to acute hemodynamic or electrophysiologic influences. [Copyright &y& Elsevier]

Abstract: Ischemia/reperfusion injury, which is commonly seen in the field of renal surgery or transplantation, is a major cause of acute renal failure. Previous studies showed that ozone oxidative preconditioning (OzoneOP) attenuated renal ischemia/reperfusion injury. The objective of this study was to examine the role of the OzoneOP in modulating inflammation and apoptosis after renal ischemia/reperfusion injury. Rats were subjected to 45 min of renal ischemia, with or without treatment with OzoneOP (1 mg/kg). Renal function, inflammation and apoptosis were compared at 24 h after renal injury. OzoneOP improved the renal dysfunction and reduced inflammation and apoptosis after ischemia/reperfusion injury. In conclusion, OzoneOP has potent anti-apoptotic and anti-inflammatory properties. These findings may have major implications in the treatment of human ischemic acute renal failure. [Copyright &y& Elsevier]

Abstract: We investigated the effects of actinonin, an inhibitor of a matrix-degrading enzyme meprin, on ischemic acute kidney injury in male and female rats, and these were compared with the effects of verapamil, a Ca2+ channel blocker. Ischemic acute kidney injury was induced by occlusion of the left renal artery and vein for 45 min followed by reperfusion, 2 weeks after contralateral nephrectomy. At 24 h after reperfusion, renal function and histology of both males and females showed significant deterioration. The degrees of renal dysfunction and histological damage were much more severe in males than in females. Pre-ischemic treatment with actinonin (10 or 30 mg/kg, i.v.) dose-dependently attenuated the ischemia/reperfusion-induced renal injury in male rats, but failed to improve the renal injury in female rats. On the other hand, verapamil (1 mg/kg, i.v.) could efficiently prevent the ischemic acute kidney injury in female rats, as well as male rats. These results indicate that the renoprotective effect of actinonin is male-specific, thereby suggesting that meprin is involved in exacerbation of ischemia/reperfusion-induced renal injury in male rats. The possibility that meprin is a key factor involved in the sex difference in the pathogenesis of ischemic acute kidney injury, warrants further attention. [Copyright &y& Elsevier]

Abstract: In addition to well-known neurobehavioral effects, endogenous cannabinoids exert diverse cardiovascular actions. Recently, they have been suggested to protect the myocardium against ischemia/reperfusion injury. The aim of this study is to examine the contribution of endogenous cannabinoids to cardioprotection afforded by remote ischemic preconditioning. Three groups of remote preconditioned (15 min of mesenteric artery occlusion followed by 15 min of reperfusion) and three groups of sham-operated rats were included in the study. Animals were pretreated intravenously by vehicle, cannabinoid CB1 (AM251, 1 mg/kg) or CB2 (AM630, 1 mg/kg) receptor antagonist 15 min prior to remote preconditioning or sham operation. Myocardial injury was induced by 30 min of coronary artery occlusion followed by 2 h of reperfusion. The resultant arterial hypotension, ventricular arrhythmias, and infarct size were compared among the groups. Remote preconditioning exerted potent cardioprotection manifested as significant reductions in infarct size (P <0.001) as well as number and duration of arrhythmias (P <0.01, 0.01 and 0.05 for premature ventricular contractions, ventricular tachycardias and fibrillations; respectively). The cannabinoid CB1 receptor antagonist pretreatment had no significant effect on ischemia-induced hypotension, arrhythmias or infarct size. On the other hand, the cannabinoid CB2 receptor antagonist pretreatment abolished the protective effects of remote preconditioning on infarct size (P <0.01) and arrhythmias (P <0.01), without any significant effect on ischemia-induced hypotension. The results of this study suggest that endogenous cannabinoids, through acting on cannabinoid CB2 receptors, are involved in the cardioprotective phenomenon of remote ischemic preconditioning, induced by mesenteric artery occlusion and reperfusion. [Copyright &y& Elsevier]

Abstract: We investigated the effects of prazosin, an α1-adrenoceptor antagonist, on the pathogenesis of ischemic acute renal failure in rats. Ischemic acute renal failure was induced by occlusion of the left renal artery and vein for 45 min followed by reperfusion, 2 weeks after contralateral nephrectomy. An in vivo microdialysis study revealed that renal interstitial norepinephrine levels were increased with the ischemia/reperfusion (n =3). Renal function in vehicle-treated acute renal failure rats markedly decreased 1 day after reperfusion (n =6), compared with those in sham-operated control animals (n =6). Pre-ischemic treatment with prazosin (100 μg/kg, i.v.) markedly and significantly attenuated the ischemia/reperfusion-induced renal dysfunction (n =6). Histopathological examination of the kidney of vehicle-treated acute renal failure rats revealed severe renal damage, which was also significantly suppressed by pre-ischemic treatment with 100 μg/kg prazosin. The same dose of prazosin given after reperfusion failed to improve the ischemia/reperfusion-induced renal dysfunction (n =6), in contrast to cases of the pre-ischemic treatment with this agent. The administration of prazosin before ischemia did not influence the elevation of renal venous plasma norepinephrine levels (n =6), which were observed both immediately and 1 day after reperfusion. From these findings, we suggest that norepinephrine released excessively from the post-ischemic kidney is involved in the pathogenesis of ischemic acute renal failure, probably acting at the postsynaptic α1-adrenoceptors. [Copyright &y& Elsevier]

Abstract: VO(OPT), bis(1-oxy-2-pyridinethiolato)oxovanadium(IV), has been shown to increase tyrosine phosphorylation of proteins and promote the insulin receptor signaling, thereby elicit anti-diabetic action. We here investigated the cytoprotective action of VO(OPT) on myocardial infarction and cardiac functional recovery in rats subjected to myocardial ischemia/reperfusion and defined mechanisms underlying its cytoprotective action. Rats underwent 30 min myocardial ischemia by left anterior descending coronary artery occlusion followed by 24 h reperfusion. Post-ischemic treatment with VO(OPT) significantly reduced infarct size and improved cardiac function (left ventricular developed pressure and ±dP/dt) after 72 h reperfusion and in a dose-dependent manner. Moreover, VO(OPT) treatment also dose-dependently significantly inhibited caspases-3, -9 and -7 processing, thereby elicited the anti-apoptotic effect. The cytoprotective effect of VO(OPT) was closely associated with restoration of Akt activity. The recovered Akt activity correlated with increased phosphorylation of Bad and forkhead transcription proteins, thereby inhibiting apoptotic signaling. Furthermore, treatment with VO(OPT) significantly increased FLIP expression, and decreased expression of Fas ligand and Bim in cardiomyocytes. Taken together, cardiomyocytes rescue following post-treatment with VO(OPT) from ischemia/reperfusion injury was mediated by increased FLIP expression and decreased Fas ligand and Bim expression via activation of Akt. These results demonstrate that treatment with VO(OPT) exerts significant cytoprotective effects along with improvement of cardiac functional recovery. [Copyright &y& Elsevier]

Abstract: Myocardial ischemia induces 5-lipoxygenase (LOX) translocation and leukotriene production in the heart. Leukotrienes increase inflammatory responses and could thereby aggravate ischemic injury. However, the role of lipoxygenase and leukotrienes in cardiac ischemia/reperfusion damage has not been well defined. Therefore, we tested the effect of ischemia reperfusion in mice with targeted deletion of 5-lipoxygenase, the enzyme converting arachidonic acid in leukotrienes. 5-LOX deficient (KO) and wild-type (WT) mice underwent 30 min of coronary artery ligation and 24 h of reperfusion in vivo. In mice with equivalent area at risk, infarct size was not significantly different between WT and KO mice (infarct/area at risk 61.7±3.9 vs. 55.8±6.6%, WT vs. KO, P =n.s.). However, neutrophil infiltration as well as tumor necrosis factor expression were increased in 5-lipoxygenase deficient mice. In summary, inhibition of 5-lipoxygenase does not affect cardiac ischemia-reperfusion injury but the post-ischemic inflammatory response. [Copyright &y& Elsevier]

Abstract: Tanshinone IIA (tan), a derivative of phenanthrenequinone, is one of the key components of Salvia miltiorrhiza Bunge. Previous reports showed that tan inhibited the apoptosis of cultured PC12 cells induced by serum withdrawal or ethanol. However, whether tan has a cardioprotective effect against apoptosis remains unknown. In this study, we investigated the effects of tan on cardiac myocyte apoptosis induced both by in vitro incubation of neonatal rat ventricular myocytes with H2O2 and by in vivo occlusion followed by reperfusion of the left anterior descending coronary artery in adult rats. In vitro, as revealed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium (MTT) assay, treatment with tan prior to H2O2 exposure significantly increased cell viability. Tan also markedly inhibited H2O2-induced cardiomyocyte apoptosis, as detected by ladder-pattern fragmentation of genomic DNA, chromatin condensation, and hypodioloid DNA content. In vivo, tan significantly inhibited ischemia/reperfusion-induced cardiomyocyte apoptosis by attenuating morphological changes and reducing the percentage of terminal transferase dUTP nick end-labeling (TUNEL)-positive myocytes and caspase-3 cleavage. These effects of tan were associated with an increased ratio of Bcl-2 to Bax protein in cardiomyocytes, an elevation of serum superoxide dismutase (SOD) activity and a decrease in serum malondialdehyde (MDA) level. Taken together, these data for the first time provide convincing evidence that tan protects cardiac myocytes against oxidative stress-induced apoptosis. The in vivo protection is mediated by increased scavenging of oxygen free radicals, prevention of lipid peroxidation and upregulation of the Bcl-2/Bax ratio. [Copyright &y& Elsevier]

Abstract: High temperature requirement A2 (HtrA2)/Omi is a mitochondrial serine protease that is released into the cytosol from mitochondria and in turn promotes caspase activation by proteolyzing inhibitor of apoptosis proteins. Here we asked whether treatment with an HtrA2/Omi inhibitor, 5-[5-(2-nitrophenyl)furfuryliodine]-1,3-diphenyl-2-thiobarbituric acid (UCF-101), restores heart dysfunction following ischemia/reperfusion injury in vivo. Rats underwent a 30-min ischemia by occluding the left anterior descending artery, followed by 24 h reperfusion. UCF-101 (0.75 or 1.5 μmol/kg, i.p.) was administered 10 min before reperfusion. UCF-101 treatment significantly recovered the mean arterial blood pressure and ameliorated contractile dysfunction of the left ventricle 72 h after reperfusion with concomitant reduction of infarct size. Cardio-protection mediated by UCF-101 was correlated with reduced X-linked inhibitor of apoptosis protein (XIAP) degradation and inhibition of Caspase-9, Caspase-3, and Caspase-7 processing. Furthermore, UCF-101 prevented loss of membrane integrity by inhibiting fodrin breakdown in cardiomyocytes. UCF-101-induced cytoprotection was also correlated with reduced Fas ligand expression and inhibition of FLIP degradation following ischemia/reperfusion. These results suggest that UCF-101 rescues cardiomyocytes from ischemia/reperfusion injury by inhibiting XIAP degradation and Fas/Fas-ligand-induced apoptosis, thereby ameliorating ischemia/reperfusion-induced myocardial dysfunction. [Copyright &y& Elsevier]

Abstract: Resveratrol (trans-3, 4′, 5-trihydroxystilbene), a natural antioxidant derived from grapes, has beneficial effects against coronary heart disease. Its electrophysiological characteristics for antiarrhythmic efficacy are largely unknown; thus, this study aims to explore the resveratrol''s antiarrhythmic effects and conduction system in isolated hearts as well as its electrophysiological effects on cardiac myocytes. In the experiment, resveratrol suppressed the ischemia/reperfusion-induced ventricular arrhythmias in Langendorff-perfused rat hearts. In the current clamp study of the experiment, resveratrol prolonged the action potential duration (APD50 and APD90) and suppressed the upstroke velocity of the action potential (V max). In the voltage clamp study, resveratrol inhibited sodium inward current (I Na) in a concentration-dependent manner and negative-shifted the voltage-dependent inactivation curve. Resveratrol also reduced the calcium inward current (I Ca, 51.2±13.3% at 100 μM). Furthermore, the transient (I to) and sustained (I ss) outward potassium currents were decreased 60.2±5.7% and 42.3±5.2% after exposure to resveratrol (100 μM), respectively. The inward rectifier potassium current (I K1) was also reduced 24.2±7.0% in the presence of resveratrol (100 μM). In the isolated heart perfusion model, resveratrol (100 μM) prolonged AV nodal refractory period, the Wenckebach cycle length and the conduction through AV node and His-Purkinje system. In conclusion, resveratrol increased the cardiac effective refractory period mainly through inhibiting the ionic channels including I Na, I to and I ss which could contribute to the conversion of ischemia/reperfusion-induced lethal arrhythmias. [Copyright &y& Elsevier]

Abstract: Brief coronary artery occlusion can protect the heart against damage during subsequent prolonged coronary artery occlusion; ischemic preconditioning. The role of calcitonin gene-related peptide (CGRP) in ischemic preconditioning is investigated in isolated perfused rat hearts, by measuring CGRP release during ischemic preconditioning and mimicking this by exogenous CGRP infusion, either in the absence or presence of the CGRP antagonist BIBN4096BS. CGRP increased left ventricular pressure and coronary flow in a concentration dependent manner, which was effectively antagonized by BIBN4096BS. Rat hearts (n =36) were subjected to 45 min coronary artery occlusion and 180 min reperfusion, which was preceded by: (1) sham pretreatment, (2) BIBN4096BS infusion (1 μM), (3) preconditioning by 15 min coronary artery occlusion and10 min reperfusion, (4) as 3, but with BIBN4096BS, (5) 15 min CGRP infusion (5 nM) and 10 min washout, (6) as 5, but with BIBN4096BS. Cardiac protection was assessed by reactive hyperaemia, creatine kinase release, infarct size related to the area at risk (%), and left ventricular pressure recovery. Preconditioning increased CGRP release into the coronary effluent from 88±13 to 154±32 pg/min/g, and significantly protected the hearts by decreasing reactive hyperaemia (35%), reducing creatine kinase release (53%), limiting infarct size (48%), and improving left ventricular pressure recovery (36%). Exogenous CGRP induced preconditioning-like cardioprotection. BIBN completely abolished the cardioprotection induced by preconditioning as well as by exogenous CGRP. In conclusion, since cardioprotection of preconditioning-induced CGRP release can be mimicked by exogenous CGRP, and both can be blocked by a CGRP antagonist, results indicate an important role for CGRP in ischemic preconditioning. [Copyright &y& Elsevier]

Abstract: Agonists of the peroxisome proliferator-activated receptor-γ (PPAR-γ) exert protective effects in several models of ischemia/reperfusion injury, but their role in stroke is less clear. The study investigates the effects of two PPAR-γ agonists, rosiglitazone and pioglitazone, on oxidative stress and inflammatory response induced by ischemia/reperfusion in the rat hippocampus. Common carotid artery occlusion for 30 min followed by 1 h reperfusion resulted in a significant increase in the generation of reactive oxygen species, nitric oxide and the end products of lipid peroxidation as well as markedly reduced endogenous antioxidant glutathione levels and up-regulated superoxide dismutase activity. Western blot analysis showed that ischemia/reperfusion lead to an increase in cyclooxygenase-2 (COX-2) expression, as well activating p38 and p42/44 mitogen-activated protein kinases (MAPKs) and nuclear factor-κB (NF-κB). Pre-treatment with either rosiglitazone or pioglitazone significantly reduced oxidative stress, COX-2 protein expression and activation of MAPKs and NF-κB. Taken together, the results provide convincing evidence that PPAR-γ agonists exert protective effects in a rat model of mild forebrain ischemia/reperfusion injury by inhibiting oxidative stress and excessive inflammatory response. [Copyright &y& Elsevier]

Abstract: Poly (ADP-ribose) polymerase-1 (PARP-1), a nuclear enzyme activated by DNA strand breaks, plays a detrimental role during inflammation. As inflammation is important in the development of colitis and ischemia/reperfusion (I/R) injury of the intestine, we investigated the effects of 10-(4-methyl-piperazin-1-ylmethyl)-2H-7-oxa-1,2-diaza-benzo[de]anthracen-3-one (GPI 15427) and 2-(4-methyl-piperazin-1-yl)-5H-benzo[c][1,5]naphthyridin-6-one (GPI 16539), two novel and potent inhibitors of PARP-1, in a rat model of gut injury and inflammation, splanchnic artery occlusion (SAO)shock and dinitrobenzene sulfonic acid (DNBS)-induced colitis. We report here for the first time that post-injury administration of GPI 15427 and GPI 16539 exerts potent anti-inflammatory effects by reducing inflammatory cell infiltration and histological injury, and delaying the development of clinical signs in both in vivo models. Furthermore, GPI 15427 and GPI 16539 treatment diminished the accumulation of poly(ADP-ribose) in the ileum of splanchnic artery occlusion-shocked rats and in the colons of dinitrobenzene sulfonic acid-treated rats. Thus, GPI 15427 and GPI 16539 exhibited anti-inflammation activity against damage caused by intestinal ischemia/reperfusion and colitis. GPI 15427 and GPI 16539 may be useful for treating gut ischemia and inflammation. [Copyright &y& Elsevier]

Abstract: To elucidate the role of nitric oxide (NO) in the pathogenesis of ischemic acute renal failure, we examined the effects of (±)-(E)-4-ethyl-2-[(E)-hydroxyimino]-5-nitro-3-hexenamide (FK409) and N G-nitro-l-arginine methyl ester (l-NAME) as a NO donor and a non-selective NO synthase inhibitor on ischemia/reperfusion-induced renal injury and renal endothelin-1 content. Ischemic acute renal failure was induced by occlusion of the left renal artery and vein for 45 min followed by reperfusion, 2 weeks after contralateral nephrectomy. At 24 h after reperfusion, renal function in untreated acute renal failure rats markedly decreased and histological examination revealed severe renal damage. In addition, increases in renal endothelin-1 contents were evident in the acute renal failure rats at 2, 6, and 24 h after reperfusion, respectively. Pretreatment with FK409 (1 or 3 mg/kg, i.v.) attenuated ischemia/reperfusion-induced renal dysfunction, histological damage, and endothelin-1 overproduction after reperfusion. In contrast, pretreatment with l-NAME (1 or 10 mg/kg, i.v.) aggravated renal injuries of acute renal failure rats at 24 h after reperfusion, and the effect is accompanied by further increases in the renal endothelin-1 content at 2 and 6 h, but not at 24 h, after reperfusion. These results suggest that suppressive effects of NO on the renal endothelin-1 overproduction induced by ischemia/reperfusion in an early phase are probably responsible for the protective effect of NO against ischemic acute renal failure. [Copyright &y& Elsevier]

Abstract: SEA0400 (2-[4-[(2,5-difluorophenyl)methoxy]phenoxy]-5-ethoxyaniline), a novel and selective inhibitor of Na+/Ca2+ exchanger, was investigated for its possible antiarrhythmic effects on arrhythmias of Ca2+ overload induced by coronary ligation/reperfusion and by digitalis in the dog. SEA0400 (1.0 mg/kg) did not change the hemodynamics but slightly prolonged the QRS duration (P&#60;0.05). Pre-ischemic administration (10 min before coronary occlusion) of SEA0400 (1.0 mg/kg) and post-ischemic administration (1 min before reperfusion) of SEA0400 (0.3, 1.0 and 3.0 mg/kg) had no effects on the incidence of ventricular fibrillation induced by coronary ligation/reperfusion. On the other hand, SEA0400 (3.0 mg/kg) decreased the arrhythmic ratio in the digitalis arrhythmias (P&#60;0.01). However, atrioventricular block and cardiac standstill were induced in two digitalized dogs. In conclusion, SEA0400 has no significant antiarrhythmic effect on arrhythmias induced by coronary ligation/reperfusion, but has an obvious suppressing effect on tachyarrhythmias induced by digitalis in in vivo canine models. [Copyright &y& Elsevier]