The Role of Autophagy and Death Pathways in Dose-dependent Isoproterenolinduced Cardiotoxicity

Background:

Isoproterenol (ISO) is a non-selective β-adrenergic agonist. Our aims were to investigate the autophagy and cell death pathways including apoptosis and necrosis in ISO-induced car-diac injury in a dose-dependent manner.

Methods:

Male Sprague-Dawley rats were treated for 24 hours with I. vehicle (saline); II. 0.005 mg/kg ISO; III. 0.05 mg/kg ISO; IV. 0.5 mg/kg ISO; V. 5 mg/kg ISO; VI. 50 mg/kg ISO, respectively. Hearts were isolated and infarct size was measured. Serum levels of Troponin T (TrT), lactate dehydrogenase (LDH), creatine kinase iso-enzyme MB (CK-MB) were measured. TUNEL assay was carried out to monitor apoptotic cell death and Western blot was performed to evaluate the level of autophagic and apoptotic markers.

Results:

Survival rate of animals was dose-dependently decreased by ISO. Serum markers and infarct size revealed the development of cardiac toxicity. Level of Caspase-3, and results of TUNEL assay, demonstrated that the level of apoptosis was dose-dependently increased. They reached the highest level in ISO 5 and it decreased slightly in ISO 50 group. Focusing on autophagic proteins, we found that level of Beclin-1 was increased in a dose-dependent manner, but significantly increased in ISO 50 treated group. Level of LC3B-II and p62 showed the same manner, but the elevated level of p62 indicated that autophagy was impaired in both ISO 5 and ISO 50 groups.

Conclusion:

Taken together these results suggest that at smaller dose of ISO autophagy may cope with the toxic effect of ISO; however, at higher dose apoptosis is initiated and at the highest dose substantial necrosis occurs.

Electrically-Induced Ventricular Fibrillation Alters Cardiovascular Function and Expression of Apoptotic and Autophagic Proteins in Rat Hearts

BACKGROUND

The pathological heart contractions, called arrhythmias, especially ventricular fibrillation (VF), are a prominent feature of many cardiovascular diseases leading to sudden cardiac death. The present investigation evaluates the effect of electrically stimulated VF on cardiac functions related to autophagy and apoptotic mechanisms in isolated working rat hearts.

METHODS

Each group of hearts was subjected to 0 (Control), 1, 3, or 10 min of spacing-induced VF, followed by 120 min of recovery period and evaluated for cardiac functions, including aortic flow (AF), coronary flow (CF), cardiac output (CO), stroke volume (SV), and heart rate (HR). Hearts were also evaluated for VF effects on infarcted zone magnitude and Western blot analysis was conducted on heart tissue for expression of the apoptotic biomarker cleaved-caspase-3 and the autophagy proteins: p62, P-mTOR/mTOR, LC3BII/LC3BI ratio, and Atg5-12 complexes.

RESULTS

Data revealed that VF induced degradation in AF, CF, CO, and SV, which prominently included-variable post-VF capacity for recovery of normal heart rhythm; increased extent of infarcted heart tissue; altered expression of cleaved-caspase-3 suggesting potential for VF-mediated amplification of apoptosis. VF influence on expression of p62, LC3BII/LC3BI, and Atg5-12 proteins was complex, possibly due to differential effects of VF-induced expression on proteins comprising the autophagic program.

CONCLUSIONS

VF was observed to cause time-dependent changes in autophagy processes, which with additional analysis under ongoing investigations, likely to yield novel therapeutic targets for the prevention of VF and sudden cardiac death.

Correction: Protective role of air potato (Dioscorea bulbifera) of yam family in myocardial ischemic reperfusion injury

Correction for 'Protective role of air potato (Dioscorea bulbifera) of yam family in myocardial ischemic reperfusion injury' by Hannah Rachel Vasanthi et al., Food Funct., 2010, 1, 278-283.

The Effects of Long-Term, Low- and High-Dose Beta-Carotene Treatment in Zucker Diabetic Fatty Rats: The Role of HO-1

Nowadays, there is a growing interest in compounds derived from plants as potential raw materials for drug development. One of the most studied compounds is beta-carotene (BC). Several clinical studies can be found investigating the cardiovascular effects of BC, however, all these results are controversial. There is an increasing body of evidence showing that besides the well-known antioxidant properties, under strong oxidative circumstances, BC could become prooxidant as well. In this study, we investigated the effects of long-term, low- and high-dose BC treatment in ischemic/reperfused (ISA/REP) hearts isolated from Zucker diabetic fatty (ZDF) rats. The animals were treated with various daily doses of BC for 4 weeks and then hearts were isolated and subjected to 30 min of global ischemia (ISA) followed by 120 min of reperfusion (REP). Blood glucose levels were measured before, after two weeks, and at the end of the treatment. In isolated hearts, the myocardial function was registered. At the end of the reperfusion period, the infarct size (IS) and heme oxygenase-1 (HO-1) expression were measured. The results showed that a low dose of BC treatment significantly improved postischemic recovery, which was reflected in a decreased IS. Interestingly, when BC was applied at high concentrations, the observed protective effects were lost. Although BC treatment increased HO-1 expression, we did not observe a better heart function and/or decreased IS in the high-dose-treated group. Glucose tolerance tests showed a concentration-independent decrease in blood glucose levels. Our results suggest that long-term, low-dose BC treatment could be effective in the treatment of type-2-diabetes and related cardiovascular diseases.

Endothelin-1-induced hypertrophic alterations and heme oxygenase-1 expression in cardiomyoblasts are counteracted by beta estradiol: in vitro and in vivo studies

Endothelin-1 (ET-1), a potent vasoconstrictor normally active in maintaining vascular tone, may mediate significant pathogenic effects, contributing to several serious diseases when aberrantly expressed or regulated. The present study evaluates the capacity of ET-1 to affect endothelin-1-associated hypertrophic activity and decreased expression of heme oxygenase-1 by H9c2 rat cardiomyoblasts in vitro, corresponding to in vivo processes underlying cardiovascular diseases (CVDs). Beta estradiol (β-E) is tested for its capacity to alter the effects of ET-1. H9c2 cells, cultured 48 h, were stimulated with 100-10,000 nM of ET-1 and evaluated for changes in cell size, cell viability, and expression of the cytoprotective heat shock protein heme oxygenase-1 (HO-1), with 200 nM of β-E included in selected cultures to evaluate its effect on ET-1-mediated changes. The application of 100 to 10,000 nM of ET-1 resulted in a significant increase in average cell size and decreases in both cell viability and HO-1 protein content (p < 0.05). Moreover, 200 nM of β-E was observed to significantly counteract these effects by cardiomyoblasts stimulated with 1000 nM of ET-1 (p < 0.05). Sprague-Dawley rats treated intravenously with 1000 ng/kg of ET-1 demonstrated reduced HO-1 expression in peripheral blood and left ventricular tissue, which was counteracted by injection of 200 ng/kg β-E-demonstrating a possible correspondence between in vitro and in vivo effects. An outcome of particular value for clinical use of β-E, in the management of cardiac hypertrophy, is the observed capacity of the drug to abate ET-1-mediated suppression of HO-1 expression. It has been previously demonstrated that HO-1 inducers exhibit potent cardioprotective properties, thus offering the promise of combining them with β-E, allowing lower effective dosage of the drug and concomitantly lower adverse side effects associated with its clinical use. Major findings of this investigation are that pretreatment of cardiomyoblasts with β-E inhibited their hypertrophic response to ET-1 and counteracts the decrease of cell viability. These effects were associated with a restoration of HO-1 protein expression in both under in vitro and in vivo conditions.

Effects of Momordica charantia (Bitter Melon) on Ischemic Diabetic Myocardium

Objective: A rat model is here used to test a hypothesis that Momordica charantia (Bitter melon (BM)) extract favorably alters processes in cardiovascular tissue and is systemically relevant to the pathophysiology of type 2 diabetes (T2DM) and related cardiovascular disease. Methods: Male Lean and Zucker Obese (ZO) rats were gavage-treated for six weeks with 400 mg/kg body weight bitter melon (BM) extract suspended in mucin–water vehicle, or with vehicle (Control). Animals were segregated into four treatment groups, 10 animals in each group, according to strain (Lean or ZO) and treatment (Control or BM). Following six-week treatment periods, peripheral blood was collected from selected animals, followed by sacrifice, thoracotomy and mounting of isolated working heart setup. Results: Body mass of both Lean and ZO rats was unaffected by treatment, likewise, peripheral blood fasting glucose levels showed no significant treatment-related effects. However, some BM treatment-related improvement was noted in postischemic cardiac functions when Lean, BM-treated animals were compared to vehicle treated Lean control rats. Treatment of Lean, but not ZO, rats significantly reduced the magnitude of infarcted zone in isolated hearts subjected to 30 min of ischemia followed by 2 h of working mode reperfusion. Immunohistochemical demonstration of caspase-3 expression by isolated heart tissues subjected to 30 min of ischemia followed by 2 h of reperfusion, revealed significant correlation between BM treatment and reduced expression of this enzyme in hearts obtained from both Lean and ZO animals. The hierarchy and order of caspase-3 expression from highest to lowest was as follows: ZO rats receiving vehicle > ZO rats receiving BM extract > Lean rats treated receiving vehicle > Lean rats administered BM extract. Outcomes of analyses of peripheral blood content of cardiac-related analytics: with particular relevance to clinical application was a significant elevation in blood of ZO and ZO BM-treated, versus Lean rats of total cholesterol (high density lipoprotein HDL-c + low density lipoprotein LDL-c), with an inferred increase in HDL-c/LDL-c ratio—an outcome associated with decreased risk of atherosclerotic disease. Conclusions: BM extract failed to positively affect T2DM- and cardiovascular-related outcomes at a level suggesting use as a standalone treatment. Nevertheless, the encouraging effects of BM in enhancement of cardiac function, suppression of post-ischemic/reperfused infarct size extent and capacity to modulate serum cholesterol, will likely make it useful as an adjuvant therapy for the management of T2DM and related cardiovascular diseases.

Autophagy: an adaptive physiological countermeasure to cellular senescence and ischaemia/reperfusion-associated cardiac arrhythmias

Oxidative stress placed on tissues that involved in pathogenesis of a disease activates compensatory metabolic changes, such as DNA damage repair that in turn causes intracellular accumulation of detritus and ‘proteotoxic stress’, leading to emergence of ‘senescent’ cellular phenotypes, which express high levels of inflammatory mediators, resulting in degradation of tissue function. Proteotoxic stress resulting from hyperactive inflammation following reperfusion of ischaemic tissue causes accumulation of proteinaceous debris in cells of the heart in ways that cause potentially fatal arrhythmias, in particular ventricular fibrillation (VF). An adaptive response to VF is occurrence of autophagy, an intracellular bulk degradation of damaged macromolecules and organelles that may restore cellular and tissue homoeostasis, improving chances for recovery. Nevertheless, depending on the type and intensity of stressors and inflammatory responses, autophagy may become pathological, resulting in excessive cell death. The present review examines the multilayered defences that cells have evolved to reduce proteotoxic stress by degradation of potentially toxic material beginning with endoplasmic reticulum‐associated degradation, and the unfolded protein response, which are mechanisms for removal from the endoplasmic reticulum of misfolded proteins, and then progressing through the stages of autophagy, including descriptions of autophagosomes and related vesicular structures which process material for degradation and autophagy‐associated proteins including Beclin‐1 and regulatory complexes. The physiological roles of each mode of proteotoxic defence will be examined along with consideration of how emerging understanding of autophagy, along with a newly discovered regulatory cell type called telocytes, may be used to augment existing strategies for the prevention and management of cardiovascular disease.

Reduction of reperfusion-induced ventricular fibrillation and infarct size via heme oxygenase-1 overexpression in isolated mouse hearts

Heme oxygenase-1 (HO-1), also known as heat shock protein 32 (hsp-32) is a stress induced cytoprotective protein. The present investigation evaluated the capacity of HO-1 to reduce the incidence of reperfusion-induced ventricular fibrillation (VF) and infarct size. HO-1 transgenic (Tg) mice were generated using a rat HO-1 genomic transgene. Isolated mouse hearts obtained from Tg and nontransgenic (NTg) groups were exposed to 20 min of global ischemia and 120 min of reperfusion. Epicardial ECG was recorded to monitor the incidence of reperfusion-induced VF and at the end of the reperfusion period, detection of HO-1 by immunohistochemistry and measurement of infarct size using the TTC method were carried out. Results shown here provide additional support for cardioprotective effects of HO-1 as evidenced by the reduced infarct size. Moreover, overexpression of the HO-1 efficiently reduced the incidence of ischemia/reperfusion (I/R)-induced VF in HO-1 Tg mice.

The cellular autophagy markers Beclin-1 and LC3B-II are increased during reperfusion in fibrillated mouse hearts

Autophagy is an intracellular bulk degradation process for elimination of damaged macromolecules and organelles. In the past decades, the scientific community has gained increasingly detailed understanding of the role of autophagy in myocardial homeostasis, although still many controversies remain. In the ischemic myocardium, autophagy appears to be beneficial for survival, whereas upon reperfusion the process may induce cell death. However, the overall effect of autophagy seems to depend on the duration and intensity of stress, as along with the extent of autophagy within myocardial tissue. Reperfusion of an ischemic heart maybe harmful, but it is an essential process for myocardial survival. One of the major adverse consequences of reperfusion is the occurrence of ventricular fibrillation (VF). In the present study, we investigated the possible connection between autophagy and VF. Isolated mouse hearts were subjected to ischemia/reperfusion (I/R) and divided into two groups based on the development of VF at the beginning of reperfusion. Western blot analysis was conducted for autophagy-associated proteins LC3B, ATG-5, ATG-7, ATG-12, Bcl-2 and Beclin-1 proteins. Significantly higher level of Beclin-1 and LC3B-II/LC3B-I ratio (both definitive autophagy biomarkers) was observed in the fibrillated myocardium, versus tissue from the nonfibrillated hearts. Interestingly, although Bcl-2 is a major regulator of Beclin-1, level of this protein was not significantly altered in tissue from fibrillated, versus non-fibrillated hearts. Moreover, Atg7 expression showed a trend, albeit nonsignificant, towards elevation in fibrillated versus non-fibrillated hearts. Results of the present investigation demonstrate a possible link between VF and autophagy. Studies by authors of this report to evaluate potential etiologic relationships between the two processes are ongoing.

Ethanol increases phosphate-mediated mineralization and osteoblastic transformation of vascular smooth muscle cells

Vascular calcification is implicated in the pathogenesis of atherosclerosis, diabetes and chronic kidney disease. Human vascular smooth muscle cells (HSMCs) undergo mineralization in response to elevated levels of inorganic phosphate (Pi) in an active and well-regulated process. This process involves increased activity of alkaline phosphatase and increased expression of core binding factor α-1 (CBF-α1), a bone-specific transcription factor, with the subsequent induction of osteocalcin. It has been shown that heavy alcohol consumption is associated with greater calcification in coronary arteries. The goal of our study was to examine whether ethanol alters mineralization of HSMCs provoked by high Pi. Exposure of HSMCs to ethanol increased extracellular matrix calcification in a dose responsive manner, providing a significant additional calcium deposition at concentrations of ≥60 mmol/l. HSMC calcification was accompanied by further enhancement in alkaline phosphatase activity. Ethanol also provoked a significant increase in the synthesis of osteocalcin. Moreover, in cells challenged with ethanol the expression of CBF-α1, a transcription factor involved in the regulation of osteoblastic transformation of HSMCs, was elevated. The observed effects of ethanol were not due to alterations of phosphate uptake by HSMCs. We conclude that ethanol enhances Pi-mediated human vascular smooth muscle calcification and transition of these cells into osteoblast-like cells.

Caveolin induces cardioprotection through epigenetic regulation

Lipid rafts represent a sub-compartment of the plasma membrane that co-ordinate and regulate varieties of signalling processes, whereas caveolins are the integral membrane protein of the lipid raft. Recent evidence demonstrated the pivotal role of caveolins in cardioprotection against ischaemic injury, although their mechanism of action is not clear. However, new understanding of epigenetic modification during ischaemia reperfusion suggests additional targeted approaches that have not been explored before. To study the role of caveolin on epigenetic regulation, isolated mouse heart was prepared from wild-type (WT) and caveolin-1 knockout (Cav-1 KO) mouse and preconditioned them with four cyclic episodes of ischaemia/reperfusion followed by 30 min. global ischaemia and 120 min. reperfusion. We found that Cav-1 KO mouse abolished the acetylation of histone (H3 and H4) and increased the methylation of histone in the preconditioned heart. The increased histone methylation was significantly correlated with an increased level of histone methyltranferase G9a protein and increased the level of histone decaetylase (HDAC) activity. Cav-1 KO mouse also decreased the translocation of forkhead transcription factor (FOXO3a) to the nucleus and reduced the induction of the expression of SIRT-1 in the preconditioned heart. Cardioprotective property of Cav-1 was further confirmed by reduced ventricular function, increased cardiomyocyte apoptosis, increased expression of junas kinase (JNK) and Bax and decreased expression of phospho-adenosine monophosphate-activated protein kinase (AMPK), phospho-AKT and B cell lymphoma-2 (Bcl-2) in Cav-1 KO preconditioned heart. The results clearly indicate that Cav-1 induces cardioprotection through epigenetic regulation.

Histamine and H1 -histamine receptors faster venous circulation

The study has analysed the action of histamine in the rabbit venous system and evaluated its potential role in contraction during increased venous pressure. We have found that a great variety exists in histamine sensitivity and H(1) -histamine receptor expression in various types of rabbit veins. Veins of the extremities (saphenous vein, femoral vein, axillary vein) and abdomen (common iliac vein, inferior vena cava) responded to histamine by a prominent, concentration-dependent force generation, whereas great thoracic veins (subclavian vein, superior vena cavas, intrathoracic part of inferior vena cava) and a pelvic vein (external iliac vein) exhibited slight sensitivity to exogenous histamine. The lack of reactivity to histamine was not due to increased activity of nitric oxide synthase (NOS) or heme oxygenase-1. H(1) -histamine receptor expression of veins correlated well with the histamine-induced contractions. Voltage-dependent calcium channels mediated mainly the histamine-induced force generation of saphenous vein, whereas it did not act in the inferior vena cava. In contrast, the receptor-operated channels were not involved in this response in either vein. Tyrosine phosphorylation occurred markedly in response to histamine in the saphenous vein, but not in the inferior vena cava. Histamine induced a prominent ρ kinase activation in both vessels. Protein kinase C and mitogen-activated protein kinase (MAPK) were not implicated in the histamine-induced intracellular calcium sensitization. Importantly, transient clamping of the femoral vein in animals caused a short-term constriction, which was inhibited by H(1) -histamine receptor antagonist in vivo. Furthermore, a significantly greater histamine immunopositivity was detected in veins after stretching compared to the resting state. We conclude that histamine receptor density adapts to the actual requirements of the circulation, and histamine liberated by the venous wall during increased venous pressure contributes to the contraction of vessels, providing a force for the venous return.

Role of haeme oxygenase-1 in resolution of oxidative stress-related pathologies: focus on cardiovascular, lung, neurological and kidney disorders

The present review examines the role of the cytoprotective enzyme haeme oxygenase-1 (HO-1) in adaptive responses to inflammatory disease and explores strategies for its clinical use, with particular emphasis on use of therapeutic use of the enzyme using phytochemical inducers of HO-1 such as extracts of Ginkgo biloba, curcumin, and flavonoids extracted from seeds of the sour cherry (Prunus cerasus). This laboratory has identified strategies by which combinations of dietary phytochemicals may be configured to synergistically strengthen immunoregulatory mechanisms that normally prevent inflammation from leading to disease. A major focus of this research initiative has been HO-1, which is capable of substantially reducing oxidative stress by several mechanisms. HO-1 metabolizes haeme that accumulates in tissues because of red blood cell turnover. Two products of this degradation - carbon monoxide (CO) and bilirubin - have potent capacity for reducing oxidative stress and for counteracting its effects. A description will be provided of how HO-1 products maintain healthy tissue function and remediate oxidative tissue damage. This will be explored in four major organ systems, including the cardiovascular system, the lungs, the central nervous system and the kidneys. Particular focus will be given to the physiological coordination of cardiovascular functions mediated by CO produced by HO-1 and to nitric oxide (NO), a gaseous second messenger expressed by nitric oxide synthetase. A major unifying theme of the present review is an exploration of the potential use of dietary phytochemical formulations as tools for the clinical application of HO-1 in therapeutic reduction of oxidative stressors, with resultant improved treatment of inflammatory pathologies.

Postischemic cardiac recovery in heme oxygenase-1 transgenic ischemic/reperfused mouse myocardium

Heme oxygenase-1 (HO-1) transgenic mice (Tg) were created using a rat HO-1 genomic transgene. Transgene expression was detected by RT-PCR and Western blots in the left ventricle (LV), right ventricle (RV) and septum (S) in mouse hearts, and its function was demonstrated by the elevated HO enzyme activity. Tg and non-transgenic (NTg) mouse hearts were isolated and subjected to ischemia/reperfusion. Significant post-ischemic recovery in coronary flow (CF), aortic flow (AF), aortic pressure (AOP) and first derivative of AOP (AOPdp/dt) were detected in the HO-1 Tg group compared to the NTg values. In HO-1 Tg hearts treated with 50 μmol/kg of tin protoporphyrin IX (SnPPIX), an HO enzyme inhibitor, abolished the post-ischemic cardiac recovery. HO-1 related carbon monoxide (CO) production was detected in NTg, HO-1 Tg and HO-1 Tg + SnPPIX treated groups, and a substantial increase in CO production was observed in the HO-1 Tg hearts subjected to ischemia/reperfusion. Moreover, in ischemia/reperfusion-induced tissue Na⁺ and Ca²⁺ gains were reduced in HO-1 Tg group in comparison with the NTg and HO-1 Tg + SnPPIX treated groups; furthermore K⁺ loss was reduced in the HO-1 Tg group. The infarct size was markedly reduced from its NTg control value of 37 ± 4% to 20 ± 6% (P < 0.05) in the HO-1 Tg group, and was increased to 47 ± 5% (P < 0.05) in the HO-1 knockout (KO) hearts. Parallel to the infarct size reduction, the incidence of total and sustained ventricular fibrillation were also reduced from their NTg control values of 92% and 83% to 25% (P < 0.05) and 8% (P < 0.05) in the HO-1 Tg group, and were increased to 100% and 100% in HO-1 KO^−/− hearts. Immunohistochemical staining of HO-1 was intensified in HO-1 Tg compared to the NTg myocardium. Thus, the HO-1 Tg mouse model suggests a valuable therapeutic approach in the treatment of ischemic myocardium.

Summative interaction between astaxanthin, Ginkgo biloba extract (EGb761) and vitamin C in suppression of respiratory inflammation: a comparison with ibuprofen

In this study, combinations of Ginkgo biloba leaf extract (EGb761) plus the carotenoid antioxidant astaxanthin (ASX) and vitamin C were evaluated for a summative dose effect in the inhibition of asthma-associated inflammation in asthmatic guinea-pigs. Ovalbumin-sensitized Hartley guinea-pigs challenged with ovalbumin aerosol to induce asthma, were administered EGb761, ASX, vitamin C or ibuprofen. Following killing, bronchoalveolar lavage (BAL) fluid was evaluated for inflammatory cell infiltrates and lung tissue cyclic nucleotide content. Each parameter measured was significantly altered to a greater degree by drug combinations, than by each component acting independently. An optimal combination was identified that included astaxanthin (10 mg/kg), vitamin C (200 mg/kg) and EGb761 (10 mg/kg), resulting in counts of eosinophils and neutrophils each 1.6-fold lower; macrophages 1.8-fold lower, cAMP 1.4-fold higher; and cGMP 2.04-fold higher than levels in untreated, asthmatic animals (p < 0.05). In conclusion, EGb761, ASX and vitamin C are shown here to interact summatively to suppress inflammation with efficacy equal to or better than ibuprofen, a widely used non-steroidal antiinflammatory drug (NSAID). Such combinations of non-toxic phytochemicals constitute powerful tools for the prevention of onset of acute and chronic inflammatory disease if consumed regularly by healthy individuals; and may also augment the effectiveness of therapy for those with established illness.

Effects of Longevinex (modified resveratrol) on cardioprotection and its mechanisms of action

Although resveratrol has been proven to possess diverse health benefits, several recent reports have demonstrated conflicting results on some aspects of its effects, including its anti-aging properties. Considerable debate appears to exist on the dose and bioavailability of resveratrol, leading to the controversies on its effectiveness. To resolve the problem, we designed a study with a resveratrol formulation that contained resveratrol supplemented with 5% quercetin and 5% rice bran phytate (commercially known as Longevinex). These ingredients were micronized to increase the bioavailability. Sprague-Dawley rats were gavaged with either Longevinex or vehicle (5% quercetin plus 5% rice bran phytate), and rats were sacrificed after 1 or 3 months, when isolated working hearts were subjected to 30 min ischemia followed by 2 h of reperfusion. Longevinex-treated hearts, irrespective of the duration of treatments, revealed superior cardiac performance, reduced infarct size, and induction of survival signals as evidenced by increased Bcl2/Bax ratio and enhanced Akt phosphorylation. In contrast, LC3-II and Beclin were enhanced significantly after 3 months of Longevinex treatment, suggesting that autophagy occurred only after feeding Longevinex to rats for a prolonged period of time. Corroborating with the results of autophagy, Sirt1 and Sirt3 increased significantly only after 3 months of Longevinex treatment, suggesting that enhanced expression of Sirts correlated with induction of autophagy. In concert, Longevinex caused phosphorylation and nuclear translocation of FoxO1, FoxO3a, and FoxO4, indicating involvement of FoxOs with autophagy. Since Sirts and FoxOs are reliable markers of longevity, the results appear to suggest that Longevinex induces longevity after prolonged feeding via induction of autophagy, while it converts death signals into survival signals and provides cardioprotection within a relatively shorter period of time.

Red wine antioxidant resveratrol-modified cardiac stem cells regenerate infarcted myocardium

To study the efficiency of maintaining the reduced tissue environment via pre-treatment with natural antioxidant resveratrol in stem cell therapy, we pre-treated male Sprague-Dawley rats with resveratrol (2.5 mg/kg/day gavaged for 2 weeks). After occlusion of the left anterior descending coronary artery (LAD), adult cardiac stem cells stably expressing EGFP were injected into the border zone of the myocardium. One week after the LAD occlusion, the cardiac reduced environment was confirmed in resveratrol-treated rat hearts by the enhanced expression of nuclear factor-E2-related factor-2 (Nrf2) and redox effector factor-1 (Ref-1). In concert, cardiac functional parameters (left ventricular ejection fraction and fractional shortening) were significantly improved. The improvement of cardiac function was accompanied by the enhanced stem cell survival and proliferation as demonstrated by the expression of cell proliferation marker Ki67 and differentiation of stem cells towards the regeneration of the myocardium as demonstrated by the enhanced expression of EGFP 28 days after LAD occlusion in the resveratrol-treated hearts. Our results demonstrate that resveratrol maintained a reduced tissue environment by overexpressing Nrf2 and Ref-1 in rats resulting in an enhancement of the cardiac regeneration of the adult cardiac stem cells as demonstrated by increased cell survival and differentiation leading to cardiac function.

Co-ordinated autophagy with resveratrol and γ-tocotrienol confers synergetic cardioprotection

This study compared two dietary phytochemicals, grape-derived resveratrol and palm oil-derived γ-tocotrienol, either alone or in combination, on the contribution of autophagy in cardioprotection during ischaemia and reperfusion. Sprague-Dawley rats weighing between 250 and 300 g were randomly assigned to one of the following groups: vehicle, ischaemia/reperfusion (I/R), resveratrol + I/R, γ-tocotrienol + I/R, resveratrol +γ-tocotrienol + I/R. For resveratrol treatments, the rats were gavaged with resveratrol (2.5 mg/kg) for 15 days while for γ-tocotrienol experiments the rats were gavaged with γ-tocotrienol (0.3 mg/kg) for 30 days. For the combined resveratrol +γ-tocotrienol experiments, the rats were gavaged with γ-tocotrienol for 15 days, and then gavaging continued with resveratrol along with γ-tocotrienol for a further period of 15 days. After 30 days, isolated perfused hearts were subjected to 30 min. of global ischaemia followed by 2 hrs of reperfusion. Our results showed for the first time that at least in part, the cardioprotection (evidenced from the ventricular performance, myocardial infarct size and cardiomyocyte apoptosis) with resveratrol and γ-toctrienol was achieved by their abilities to induce autophagy. Most importantly, resveratrol and γ-tocotrienol acted synergistically providing greater degree of cardioprotection simultaneously generating greater amount of survival signal through the activation of Akt-Bcl-2 survival pathway. Autophagy was accompanied by the activation of Beclin and LC3-II as well as mTOR signalling, which were inhibited by either 3-methyl adenine (3-MA) or Wortmannin. The autophagy was confirmed from the results of transmission electron microscopy and light microscopy as well as with confocal microscopy. It is tempting to speculate that during ischaemia and reperfusion autophagy along with enhanced survival signals helps to recover the cells from injury.

Isolation and analysis of bioactive constituents of sour cherry (Prunus cerasus) seed kernel: an emerging functional food

A plant-based diet reduces the risk for the development of several chronic diseases, such as ischemic heart disease or cancer due to natural compounds found in plants. Numerous cereals, berries, fruits, and vegetables, including sour cherry (Prunus cerasus), which is a favored fruit worldwide, contain biological active components. The antioxidant components of the sour cherry seed kernel have not been investigated until now. The aim of our study was to isolate and analyze the bioactive constituents of sour cherry seed kernel. We separated the oil fraction of the kernel; then the remaining solid fraction was dried, and the oil-free kernel extract was further analyzed. Our results show that sour cherry seed kernel oil contains vegetable oils including unsaturated fatty acids, oleic acids, alpha-tocopherol, tocotrienols, and tocopherol-like components. The components of the solid fraction include various bioactive structures such as polyphenols, flavonoids, vegetable acids, and pro- and anthocyanidins, which could have useful therapeutic effects in the prevention of various vascular diseases.

Protective role of air potato (Dioscorea bulbifera) of yam family in myocardial ischemic reperfusion injury

Hydroalcoholic extract of Dioscorea bulbifera (DB), a yam variety called air potato, was tested for its protective effect on myocardial ischemic/reperfusion (I/R) injury in rats due to apoptosis and necrosis. Myocardial I/R injury was induced by 30 min ischemia followed by 2 h reperfusion by perfusing isolated rat hearts with Krebs Henseilet bicarbonate (KHB) buffer in a Langendorff set up. Pretreatment of DB (150 mg kg(-1) body weight) for 30 days significantly reduced myocardial infarct size and improved the ventricular function (aortic flow and coronary flow, LVDP, LVmax dp/dt). Role of DB on apoptosis was also evaluated by determining caspase 3 as well as by examining pro-apoptotic and anti-apoptotic proteins Bax and Bcl2 by Western blot analysis followed by TUNEL assay. DB also prevented I/R-mediated down regulation of survival protein Akt and HO-1. Our results indicated that Dioscorea bulbifera could ameliorate myocardial ischemia and reperfusion injury by improving ventricular function and inhibition of cardiomyocyte necrosis and apoptosis.

Downregulation of cardiac lineage protein-1 confers cardioprotection through the upregulation of redox effectors

CLP-1, the mouse homologue of human Hexim1 protein, exerts inhibitory control on transcriptional elongation factor-b of RNA transcript elongation. Previously, we have demonstrated that downregulation of cardiac lineage protein-1 (CLP-1) in CLP-1(+/-) heterozygous mice affords cardioprotection against ischemia-reperfusion injury. Our current study results show that the improvement in cardiac function in CLP-1(+/-) mice after ischemia-reperfusion injury is achieved through the potentiation of redox signaling and their molecular targets including redox effector factor-1, nuclear factor erythroid 2-related factor, and NADPH oxidase 4 and the active usage of thioredoxin-1, thioredoxin-2, glutaredoxin-1 and glutaredoxin-2. Our results suggest that drugs designed to down regulate CLP-1 could confer cardioprotection through the potentiation of redox cycling.

Cardioprotection by resveratrol: a novel mechanism via autophagy involving the mTORC2 pathway

AIMS

On the basis of our previous reports that cardioprotection induced by ischaemic preconditioning induces autophagy and that resveratrol, a polyphenolic antioxidant present in grapes and red wine induces preconditioning-like effects, we sought to determine if resveratrol could induce autophagy.

METHODS AND RESULTS

Resveratrol at lower doses (0.1 and 1 microM in H9c2 cardiac myoblast cells and 2.5 mg/kg/day in rats) induced cardiac autophagy shown by enhanced formation of autophagosomes and its component LC3-II after hypoxia-reoxygenation or ischaemia-reperfusion. The autophagy was attenuated with the higher dose of resveratrol. The induction of autophagy was correlated with enhanced cell survival and decreased apoptosis. Treatment with rapamycin (100 nM), a known inducer of autophagy, did not further increase autophagy compared with resveratrol alone. Autophagic inhibitors, wortmannin (2 microM) and 3-methyladenine (10 mM), significantly attenuated the resveratrol-induced autophagy and induced cell death. The activation of mammalian target of rapamycin (mTOR) was differentially regulated by low-dose resveratrol, i.e. the phosphorylation of mTOR at serine 2448 was inhibited, whereas the phosphorylation of mTOR at serine 2481 was increased, which was attenuated with a higher dose of resveratrol. Although resveratrol attenuated the activation of mTOR complex 1, low-dose resveratrol significantly induced the expression of Rictor, a component of mTOR complex 2, and activated its downstream survival kinase Akt (Ser 473). Resveratrol-induced Rictor was found to bind with mTOR. Furthermore, treatment with Rictor siRNA attenuated the resveratrol-induced autophagy.

CONCLUSION

Our results indicate that at lower dose, resveratrol-mediated cell survival is, in part, mediated through the induction of autophagy involving the mTOR-Rictor survival pathway.

Redox regulation of stem cell mobilizationThis article is one of a selection of papers published in a special issue on Advances in Cardiovascular Research

A growing body of evidence supports the role of redox signaling in the mechanisms of hematopoietic stem cell mobilization and homing. Cytokines and adhesion molecules control stem cell mobilization through a redox-regulated process. The FoxO–SirT network appears to be intimately involved in redox-regulated stem cell homeostasis, whereas the process of stem cell differentiation is regulated by redox effector factor-1 (Ref-1) protein. Lack of oxygen (hypoxia), specifically controlled hypoxia, can stimulate the growth of the stem cells in their niche, and hypoxia-inducible factor (HIF)-1α appears to play a significant role in their maintenance and homing mechanism.

Redox regulation of cell survival by the thioredoxin superfamily: an implication of redox gene therapy in the heart

Reactive oxygen species (ROS) are the key mediators of pathogenesis in cardiovascular diseases. Members of the thioredoxin superfamily take an active part in scavenging reactive oxygen species, thus playing an essential role in maintaining the intracellular redox status. The alteration in the expression levels of thioredoxin family members and related molecules constitute effective biomarkers in various diseases, including cardiovascular complications that involve oxidative stress. Thioredoxin, glutaredoxin, peroxiredoxin, and glutathione peroxidase, along with their isoforms, are involved in interaction with the members of metabolic and signaling pathways, thus making them attractive targets for clinical intervention. Studies with cells and transgenic animals have supported this notion and raised the hope for possible gene therapy as modern genetic medicine. Of all the molecules, thioredoxins, glutaredoxins, and peroxiredoxins are emphasized, because a growing body of evidence reveals their essential and regulatory role in several steps of redox regulation. In this review, we discuss some pertinent observations regarding their distribution, structure, functions, and interactions with the several survival- and death-signaling pathways, especially in the myocardium.

Freshly crushed garlic is a superior cardioprotective agent than processed garlic

In this study, we compared the cardioprotective effects of freshly crushed garlic vis-a-vis that of processed garlic. Two groups of rats were gavaged with respective garlic preparations while the control group received vehicle only. After 30 days, all of the rats were sacrificed and isolated the hearts were subjected to 30 min ischemia followed by 2 h of reperfusion. Both of the garlic preparations provided cardioprotection, but superior cardiac performance was noticed for those fed with freshly crushed garlic. Consistent with these results, the freshly crushed garlic group displayed significantly greater phosphorylation of antiapoptotic ERK1/2 proteins, reduced Bax/Bcl-2 ratio, and reduced phosphorylation of proapoptotic p-38MAPK and JNK. Moreover, the survival signaling network consisting of Akt-FoxO1 was increased in the freshly crushed garlic treated hearts. Freshly crushed garlic, but not the processed garlic, showed enhanced redox signaling as evident by increased level of p65 subunit of NFkappaB, Nrf2, and enhanced GLUT 4, PPARalpha, and PPARdelta. The results thus show that although both freshly crushed garlic and processed garlic provide cardioprotection, the former has additional cardioprotective properties presumably due to the presence of H2S.

Expression of the longevity proteins by both red and white wines and their cardioprotective components, resveratrol, tyrosol, and hydroxytyrosol

Resveratrol increases longevity through SirT1, which is activated with NAD(+) supplied by an anti-aging enzyme PBEF. SirT1 interacts with an anti-aging transcription factor, FoxO1, which is negatively regulated by Akt. Since white wine could have similar health benefits as red wine, we determined if white wine and its cardioprotective components possess anti-aging properties by feeding rats with these compounds. The hearts expressed SirT, FoxO, and PBEF in the order of white wine>resveratrol>tyrosol>hydroxytyrosol>red wine, while cardioprotection shown by reduction of infarct size and cardiomyocyte apoptosis followed a different pattern: resveratrol>red wine>hydroxytyrosol>white wine>tyrosol, suggesting the existence of different signaling mechanisms for the induction of longevity and survival.

Inhibition of ref-1 stimulates the production of reactive oxygen species and induces differentiation in adult cardiac stem cells

Redox effector protein-1 (Ref-1) plays an essential role in DNA repair and redox regulation of several transcription factors. In the present study, we examined the role of Ref-1 in maintaining the redox status and survivability of adult cardiac stem cells challenged with a subtoxic level of H2O2 under inhibition of Ref-1 by RNA interference. Treatment of cardiac stem cells with a low concentration of H2O2 induced Ref-1-mediated survival signaling through phosphorylation of Akt. However, Ref-1 inhibition followed by H2O2 treatment extensively induced the level of intracellular reactive oxygen species (ROS) through activation of the components of NADPH oxidase, like p22( phox ), p47( phox ), and Nox4. Cardiac differentiation markers (Nkx2.5, MEF2C, and GATA4), and cell death by apoptosis were significantly elevated in Ref-1 siRNA followed by H2O2-treated stem cells. Further, inhibition of Ref-1 increased the level of p53 but decreased the phosphorylation of Akt, a molecule involved in survival signaling. Treatment with ROS scavenger N-acetyl-L-cysteine attenuated Ref-1 siRNA-mediated activation of NADPH oxidase and cardiac differentiation. Taken together, these results indicate that Ref-1 plays an important role in maintaining the redox status of cardiac stem cells and protects them from oxidative injury-mediated cell death and differentiation.

Cardioprotection by adaptation to ischaemia augments autophagy in association with BAG-1 protein

Autophagy is an intracellular process in which a cell digests its own constituents via lysosomal degradative pathway. Though autophagy has been shown in several cardiac diseases like heart failure, hypertrophy and ischaemic cardiomyopathy, the role and the regulation of autophagy is still largely unknown. Bcl-2-associated athanogene (BAG-1) is a multifunctional pro-survival molecule that binds with Hsp70/Hsc70. In this study, myocardial adaptation to ischaemia by repeated brief episodes of ischaemia and reperfusion (I/R) prior to lethal I/R enhanced the expression of autophagosomal membrane specific protein light chain 3 (LC3)-II, and Beclin-1, a molecule involved in autophagy and BAG-1. Autophagosomes structures were found in the adapted myocardium through electron microscopy. Co-immunoprecipitation and co-immunofluorescence analyses revealed that LC3-II was bound with BAG-1. Inhibition of autophagy by treating rats with Wortmannin (15 microg/kg; intraperitoneally) abolished the ischaemic adaptation-induced induction of LC3-II, Beclin-1, BAG-1 and cardioprotection. Intramyocardial injection of BAG-1 siRNA attenuated the induction of LC3-II, and abolished the cardioprotection achieved by adaptation. Furthermore, hypoxic adaptation in cardiac myoblast cells induced LC3-II and BAG-1. BAG-1 siRNA treatment attenuated hypoxic adaptation-induced LC3-II and BAG-1, and abolished improvement in cardiac cell survival and reduction of cell death. These results clearly indicate that myocardial protection elicited by adaptation is mediated at least in part via up-regulation of autophagy in association with BAG-1 protein.

BAG-1 induces autophagy for cardiac cell survival

The Bcl-2 associated athanogene (BAG) family of proteins function as cochaperones by bridging molecules that recruit molecular chaperones to target proteins. BAG-1 provides a physical link between the heat shock proteins Hsc70/Hsp70 and the proteasome to facilitate ubiquitin-proteasome-mediated protein degradation. In addition to the proteasome, protein degradation via autophagy is responsible for maintaining cellular metabolism, organelle homeostasis and redox equilibrium. Our recent report shows that autophagy plays an important role in cardiac adaptation-induced cell survival against ischemia-reperfusion injury in association with the BAG-1 protein. BAG-1 is associated with the autophagosomal membrane protein LC3-II and it may participate in the induction of autophagy via Hsc70. Moreover, another BAG family member, BAG-3, is responsible for the induction of macroautophagy in association with HspB8. These results show the involvement of BAG family members in the induction of autophagy for the degradation of damaged or oxidized proteins to promote cell survival.

Does white wine qualify for French paradox? Comparison of the cardioprotective effects of red and white wines and their constituents: resveratrol, tyrosol, and hydroxytyrosol

It is generally believed that the French paradox is related to the consumption of red wine and not other varieties of wine, including white wine or champagne. Some recent studies have indicated that white wine could also be as cardioprotective as red wine. The present investigation compares the cardioprotective abilities of red wine, white wine, and their principal cardioprotective constituents. Different groups of rats were gavaged with red wine, white wine, resveratrol, tyrosol, and hydroxytyrosol. Red wine and its constituent resveratrol and white wine and its constituents tyrosol and hydroxytyrosol all showed different degrees of cardioprotection as evidenced by their abilities to improve postischemic ventricular performance, reduce myocardial infarct size and cardiomyocyte apoptosis, and reduce peroxide formation. It was discovered in this study that although each of the wines and their components increased the enzymatic activities of the mitochondrial complex (I-IV) and citrate synthase, which play very important roles in oxidative phosphorylation and ATP synthesis, some of the groups were more complex-specific in inducing the activity compared to the other groups. Cardioprotective ability was further confirmed by increased expression of phospho-Akt, Bcl-2, eNOS, iNOS, COX-1, COX-2, Trx-1, Trx-2, and HO-1. The results of this study suggest that white wine can provide cardioprotection similar to red wine if it is rich in tyrosol and hydroxytyrosol.

Coenzyme Q9 provides cardioprotection after converting into coenzyme Q10

Coenzyme Q10 (CoQ10) has been extensively studied as adjunctive therapy for ischemic heart disease, and its cardioprotective ability is well-established. The mitochondrial respiratory chain contains several coenzymes, including CoQ1, CoQ2, CoQ4, CoQ6, CoQ7, CoQ8, CoQ9, and CoQ10. It is not known whether other CoQs, especially CoQ9, is equally cardioprotective as CoQ10. The present study was designed to determine if CoQ 9 could protect guinea pig hearts from ischemia reperfusion injury. Guinea pigs were randomly divided into three groups: groups I and II were fed CoQ 9 and CoQ10, respectively, for 30 days while group III served as control. After 30 days, the guinea pigs were sacrificed and isolated hearts were perfused via working mode were subjected to 30 min ischemia followed by 2 h of reperfusion. Cardioprotection was assessed by evaluating left ventricular function, ventricular arrhythmias, myocardial infarct size, and cardiomyocyte apoptosis. Samples of hearts were examined for the presence of CoQ9 and CoQ10. The results demonstrated that both CoQ9 and CoQ10 were equally cardioprotective, as evidenced by their abilities to improve left ventricular performance and to reduce myocardial infarct size and cardiomyocyte apoptosis. High performance liquid chromatographic (HPLC) analysis revealed that a substantial portion of CoQ9 had been converted into CoQ10. The results indicate that CoQ9 by itself, or after being converted into CoQ10, reduced myocardial ischemia/reperfusion-induced injury.

Cardioprotection with alpha-tocopheryl phosphate: amelioration of myocardial ischemia reperfusion injury is linked with its ability to generate a survival signal through Akt activation

The emerging potential of alpha-tocopheryl phosphate, a phosphoric acid ester of alpha-tocopherol, in health benefits was tested gavaging this compound (5 mg/kg body wt) to a group of rats for a period of thirty days while the control rats were given water only. After thirty days, the rats were sacrificed, the hearts excised, and the isolated hearts were perfused by working mode. Both control and experimental hearts were subjected to 30-min global ischemia followed by 2 h of reperfusion. The tocopheryl phosphate fed rats exhibited significant cardioprotection as evidenced by improved ventricular performance and reduced myocardial infarct size and cardiomyocyte apoptosis. Supplementation with alpha-tocopheryl phosphate converted MAP kinase-induced death signal into a survival signal by enhancing anti-apoptotic p42/44 ERK kinase and p38 MAPKbeta and reducing pro-apoptotic proteins p38 MAPKalpha and JNK. In concert, the phosphorylation of pro-apoptotic c-Src was also reduced. Tocopheryl phosphate increased the DNA binding of the redox-sensitive transcription factor NFkappaB and potentiated the activation of anti-death protein Bcl-2 and survival signaling protein Akt. The results of this study demonstrated for the first time that tocopheryl phosphate could ameliorate myocardial ischemic reperfusion injury by converting ischemia/reperfusion-mediated death signal into a survival signal by modulating MAP kinase signaling.

Essential role of lipid raft in ischemic preconditioning

Lipid rafts represent a subcompartment of the plasma membrane that coordinate and regulate varieties of signaling processes while caveolins are the integral membrane protein of the lipid raft. To study the role of lipid raft in ischemic preconditioning (PC) of the heart, rat hearts were perfused by working mode and then preconditioned in absence or presence of a lipid raft disintegrator, Methyl-beta-cyclodextrin. As expected, precondition made the heart resistant to ischemia reperfusion (I/R) injury as evident by improved ventricular performance, reduced myocardial infract size and cardiomyocyte apoptosis. Cyclodextrin abolished the cardioprotection. Transmission Electron Microscopy revealed severe degeneration, swelling of mitochondria, chromatin condensation and myofibril disarray in cyclodextrin treated PC heart similar to I/R heart. In the PC hearts, there was an increased association of the proapoptotic p38MAPKalpha with caveolin-1 while there was a reduced association of anti-apoptotic p38MAPKbeta with caveolin-3 indicating that reduced amount of p38MAPKalpha and increased amount of p38MAPKbeta were available to the adapted hearts thereby generating a survival signal. In contrast, there was very weak caveolin-MAP kinase interaction in cyclodextrin treated heart. Myocardial damage was further confirmed by reduced or no expression of anti-apoptotic phospho-AKT, Bcl2, Bcl-xl and increased expression of pro-apoptotic JNK, BAX, and p53 in methyl-beta-cyclodextrin (lipid raft disintegrator) treated heart. These results indicate that lipid raft play a pivotal role in the generation of survival signal in PC or adapted heart and disintegration of lipid raft completely abolish cardioprotection.

Cardioprotection with palm oil tocotrienols: comparision of different isomers

A recent study from our laboratory indicated the cardioprotective ability of the tocotrienol-rich fraction (TRF) from red palm oil. The present study compared cardioprotective abilities of different isomers of tocotrienol against TRF as recently tocotrienol has been found to function as a potent neuroprotective agent against stroke. Rats were randomly assigned to one of the following groups: animals were given, by gavage, either 0.35%, 1%, or 3.5% TRF for two different periods of time (2 or 4 wk) or 0.03, 0.3, and 3 mg/kg body wt of one of the isomers of tocotrienol (alpha, gamma, or delta) for 4 wk; control animals were given, by gavage, vehicle only. After 2 or 4 wk, rats were killed, and their hearts were then subjected to 30 min of global ischemia followed by 2 h of reperfusion. Dose-response and time-response experiments revealed that the optimal concentration for TRF was 3.5% TRF and 0.3 mg/kg body wt of tocotrienol given for 4 wk. TRF as well as all the isomers of tocotrienol used in our study provided cardioprotection, as evidenced by their ability to improve postischemic ventricular function and reduce myocardial infarct size. The gamma-isoform of tocotrienol was the most cardioprotective of all the isomers followed by the alpha- and delta-isoforms. The molecular mechanisms of cardioprotection afforded by tocotrienol isoforms were probed by evaluating their respective abilities to stabilize the proteasome, allowing it to maintain a balance between prodeath and prosurvival signals. Our results demonstrated that tocotrienol isoforms reduced c-Src but increased the phosphorylation of Akt, thus generating a survival signal.

Protective mechanisms of resveratrol against ischemia-reperfusion-induced damage in hearts obtained from Zucker obese rats: the role of GLUT-4 and endothelin

The resveratrol-induced cardiac protection was studied in Zucker obese rats. Rats were divided into five groups: group 1, lean control; group 2, obese control (OC); group 3, obese rats treated orally with 5 mg kg(-1) day(-1) of resveratrol (OR) for 2 wk; group 4, obese rats received 10% glucose solution ad libitum for 3 wk (OG); and group 5, obese rats received 10% glucose for 3 wk and resveratrol (OGR) during the 2nd and 3rd wk. Body weight, serum glucose, and insulin were measured, and then hearts were isolated and subjected to 30 min of ischemia followed by 120 min of reperfusion. Heart rate, coronary flow, aortic flow, developed pressure, the incidence of reperfusion-induced ventricular fibrillation, and infarct size were measured. Resveratrol reduced body weight and serum glucose in the OR compared with the OC values (414 +/- 10 g and 7.08 +/- 0.41 mmol/l, respectively, to 378 +/- 12 g and 6.11 +/- 0.44 mmol/l), but insulin levels were unchanged. The same results were obtained for the OG vs. OGR group. Resveratrol improved postischemic cardiac function in the presence or absence of glucose intake compared with the resveratrol-free group. The incidence of ventricular fibrillation and infarct size was reduced by 83 and 20% in the OR group, and 67 and 16% in the OGR group, compared with the OC and OG groups, respectively. Resveratrol increased GLUT-4 expression and reduced endothelin expression and cardiac apoptosis in ischemic-reperfused hearts in the presence or absence of glucose intake. Thus the protective effect of resveratrol could be related to its direct effects on the heart.

Adrenocorticotrope hormone fragment (4-10) attenuates the ischemia/reperfusion-induced cardiac injury in isolated rat hearts

The aim of our study was to investigate the contribution of the adrenocorticotropic hormone fragment, ACTH (4-10), on the recovery of postischemic cardiac function. Effects of ACTH (4-10) on caspase-3 activity, cardiomyocyte and endothelial apoptosis, and HO-1 protein expression were studied. Rats were treated with various doses of ACTH (4-10), and then 12 h later, anesthetized, hearts were isolated, perfused, and subjected to 30-min ischemia followed by 120-min reperfusion. Cardiac function including heart rate, coronary flow, aortic flow, and left ventricular developed pressure were recorded. After 120-min reperfusion, 200 mug/kg of ACTH (4-10) significantly improved the recovery of aortic flow, coronary flow, and left ventricular developed pressure from their untreated control values of 15.3 +/- 0.9 ml/min, 6.5 +/- 0.9 ml/min, and 10 +/- 0.6 kPa to 20.7 +/- 1.3 ml/min, 24.8 +/- 1.8 ml/min and 13.7 +/- 0.7 kPa, respectively. Heart rate did not show significant changes during reperfusion. ACTH (4-10) treatment resulted in a reduction in infarct size, caspase 3 activity, apoptosis, and an increase in HO-1 expression. When ACTH (4-10) was given at the moment of reperfusion, the drug failed to improve the postischemic recovery of the myocardium. Thus, ACTH (4-10) can be a useful tool for the prevention of the development of ischemia/reperfusion-induced injury.

Beneficial effects of carbon monoxide-releasing molecules on post-ischemic myocardial recovery

There is increasing evidence corroborating a protective role of carbon monoxide releasing molecules (CORMs) in injured tissues. Carbon monoxide (CO) carriers have been recently developed as a pharmacological tool to simulate the effect of heme oxygenase-1-derived CO. The effects of CORM-3, a water-soluble CO releaser, on the incidence of reperfusion-induced ventricular fibrillation (VF) and tachycardia (VT) were studied in isolated rat hearts. Hearts were treated with different doses of CORM-3 before the induction of 30 min global ischemia followed by 120 min reperfusion. We found that at concentrations of 25 microM and 50 microM of CORM-3 promoted a significant reduction in the incidence of VF and VT. Thus, the incidence of VF was reduced by 67% (p<0.05) and 92% (p<0.05) with 25 microM and 50 microM of CORM-3, respectively. The protective effect of CORM-3 on the incidence of VT followed the same pattern. The antiarrhythmic protection was associated with a marked attenuation in infarct size, significant decreases in cellular Na(+) and Ca(2+) gains and K(+) loss. Consequently, the recovery of post-ischemic function was significantly improved. In conclusion, CORM-3 exerts beneficial effects against ischemia/reperfusion-induced injury through its abilities to release CO which mediates a cardioprotective action by regulating tissue Na(+), K(+), and Ca(2+) levels.

Influence of hyperthyroidism on the effect of adenosine transport blockade assessed by a novel method in guinea pig atria

The aim of the present study was to investigate the effect of hyperthyroidism on the trans-sarcolemmal adenosine (Ado) flux via equilibrative and nitrobenzylthioinosine (NBTI)-sensitive nucleoside transporters (ENT1) in guinea pig atria, by assessing the change in the Ado concentration of the interstitial fluid ([Ado]ISF) under nucleoside transport blockade with NBTI. For the assessment, we applied our novel method, which estimates the change in [Ado]ISF utilizing the altered inotropic response to N6-cyclopentyladenosine (CPA), a relative stable selective agonist of A1 Ado receptors, by providing a relative index, the equivalent concentration of CPA. Our results show an interstitial Ado accumulation upon ENT1 blockade, which was more extensive in the hyperthyroid samples (CPA concentrations equieffective with the surplus [Ado]ISF were two to three times higher in hyperthyroid atria than in euthyroid ones, with regard to the negative inotropic effect of CPA and Ado). This suggests an enhanced Ado influx via ENT1 in hyperthyroid atria. It is concluded that hyperthyroidism does not alter the prevailing direction of the Ado transport, moreover intensifies the Ado influx in the guinea pig atrium.