Beyond cardiomyocytes:Cellular diversity in the heart's response to exercise

Cardiomyocytes comprise~70%to 85%of the total volume of the adult mammalian heart but only about 25%to 35%of its total number of cells.Advances in single cell and single nuclei RNA sequencing have greatly facilitated investigation into and increased appreciation of the potential functions of non-cardiomyocytes in the heart.While much of this work has focused on the relationship between non-cardiomyocytes,disease,and the heart's response to pathological stress,it will also be important to understand the roles that these cells play in the healthy heart,cardiac homeostasis,and the response to physiological stress such as exercise.The present review summarizes recent research highlighting dynamic changes in non-cardiomyocytes in response to the physiological stress of exercise.Of particular interest are changes in fibrotic pathways,the cardiac vasculature,and immune or inflammatory cells.In many instances,limited data are available about how specific lineages change in response to exercise or whether the changes observed are functionally important,underscoring the need for further research.

Ischemia/reperfusion injury and cardioprotective mechanisms:Role of mitochondria and reactive oxygen species

Reperfusion therapy must be applied as soon as possible to attenuate the ischemic insult of acute myocardial infarction(AMI).However reperfusion is responsible for additional myocardial damage,which likely involves opening of the mitochondrial permeability transition pore(mPTP).In reperfusion injury,mitochondrial damage is a determining factor in causing loss of cardiomyocyte function and viability.Major mechanisms of mitochondrial dysfunction include the long lasting opening of mPTPs and the oxidative stress resulting from formation of reactive oxygen species(ROS).Several signaling cardioprotective pathways are activated by stimuli such as preconditioning and postconditioning,obtained with brief intermittent ischemia or with pharmacological agents.These pathways converge on a common target,the mitochondria,to preserve their function after ischemia/reperfusion.The present review discusses the role of mitochondria in cardioprotection,especially the involvement of adenosine triphosphate-dependent potassium channels,ROS signaling,and the mPTP.Ischemic postconditioning has emerged as a new way to target the mitochondria,and to drastically reduce lethal reperfusion injury.Several clinical studies using ischemic postconditioning during angioplasty now support its protective effects,and an interesting alternative is pharmacological postconditioning.In fact ischemic postconditioning and the mPTP desensitizer,cyclosporine A,have been shown to induce comparable protection in AMI patients.

Recent advances in the diagnosis and treatment of acute myocardial infarction

The Third Universal Definition of Myocardial Infarction(MI) requires cardiac myocyte necrosis with an increase and/or a decrease in a patient's plasma of cardiac troponin(cT n) with at least one cT n measurement greater than the 99 th percentile of the upper normal reference limit during:(1) symptoms of myocardialischemia;(2) new significant electrocardiogram(ECG) ST-segment/T-wave changes or left bundle branch block;(3) the development of pathological ECG Q waves;(4) new loss of viable myocardium or regional wall motion abnormality identified by an imaging procedure; or(5) identification of intracoronary thrombus by angiography or autopsy.Myocardial infarction,when diagnosed,is now classified into five types.Detection of a rise and a fall of troponin are essential to the diagnosis of acute MI.However,high sensitivity troponin assays can increase the sensitivity but decrease the specificity of MI diagnosis.The ECG remains a cornerstone in the diagnosis of MI and should be frequently repeated,especially if the initial ECG is not diagnostic of MI.There have been significant advances in adjunctive pharmacotherapy,procedural techniques and stent technology in the treatment of patients with MIs.The routine use of antiplatelet agents such as clopidogrel,prasugrel or ticagrelor,in addition to aspirin,reduces patient morbidity and mortality.Percutaneous coronary intervention(PCI) in a timely manner is the primary treatment of patients with acute ST segment elevation MI.Drug eluting coronary stents are safe and beneficial with primary coronary intervention.Treatment with direct thrombin inhibitors during PCI is non-inferior to unfractionated heparin and glycoprotein Ⅱb/Ⅲa receptor antagonists and is associated with a significant reduction in bleeding.The intra-coronary use of a glycoprotein Ⅱb/Ⅲa antagonist can reduce infarct size.Pre- and post-conditioning techniques can provide additional cardioprotection.However,the incidence and mortality due to MI continues to be high despite all these recent advances.The initial ten year experience with autologous human bone marrow mononuclear cells(BMCs) in patients with MI showed modest but significant increases in left ventricular(LV) ejection fraction,decreases in LV endsystolic volume and reductions in MI size.These studies established that the intramyocardial or intracoronary administration of stem cells is safe.However,many of these studies consisted of small numbers of patients who were not randomized to BMCs or placebo.The recent LateT ime,Time,and Swiss Multicenter Trials in patientswith MI did not demonstrate significant improvement in patient LV ejection fraction with BMCs in comparison with placebo.Possible explanations include the early use of PCI in these patients,heterogeneous BMC populations which died prematurely from patients with chronic ischemic disease,red blood cell contamination which decreases BMC renewal,and heparin which decreases BMC migration.In contrast,cardiac stem cells from the right atrial appendage and ventricular septum and apex in the SCIPIO and CADUCEUS Trials appear to reduce patient MI size and increase viable myocardium.Additional clinical studies with cardiac stem cells are in progress.

Protective effect of hyperoside on cardiac ischemia reperfusion injury through inhibition of ER stress and activation of Nrf2 signaling

Objective:To study the protective effect of hyperoside(Hyp) on cardiac ischemia reperfusion injury and its potential mechanism.Methods:Rats were divided into two groups for the evaluation,the Hyp(50 uM Hyp;n=8) and the control group(n=8).Rat hearts were isolated and perfused with Krebs-Henseleit buffer(KHB) for 30 min.After being inhibited with cardioplegic solution,they were stored for 4 h in B21 solution at 4℃.Afterwards,rat hearts were perfused with KHB again for 45 min.In this period.Hyp was added into solutions of cardioplegia for storage and KHB.Parameters of cardiac functions,including heart rate,the systolic pressure of the left ventricle,the end-diastolic pressure of the left ventricle,the developed pressure of the left ventricle,the left-ventricular systolic pressure and the peak rise rate of the pressure of the left ventricle were recorded.The levels of adenosine triphosphate(ATP),the content of malondialdehyde and apoptotic cells were determined to evaluate the protective effect of Hyp on hearts suffered from ischemia reperfusion injury.Moreover,cultured cardiac myocytes were subjected to the process simulating ischemia/reperfusion.What were analyzed included the endoplasmic reticulum(ER) stress hallmarks expressions,such as binding immunoglobulin protein and C/EBP homologous protein,using the western blot and real-time PCR.Besides,the NF-E2-related factor 2(Nrf2) expression was measured to explore the potential mechanism.Results:Compared with the control group,the Hyp group had better cardiac functional parameters and higher ATP levels;pretreatment of Hyp greatly relieved the apoptosis of myocyte,decreased oxidative stress as well as ER stress and activated the signaling pathway of anti-oxidative Nrf2 to a further extent.Conclusions:Hyp plays an important role in preserving cardiac function by improving ATP levels of tissue,easing oxidative injury of myocardium and reducing apoptosis following IRI dramatically,while the ER stress inhibition and the downstream Nrf2 signaling activation may contribute to the effects of protection.

Cardioprotection and pharmacological therapies in acute myocardial infarction: Challenges in the current era

In patients with an acute ST-segment elevation myocardial infarction, timely myocardial reperfusion using primary percutaneous coronary intervention is the most effective therapy for limiting myocardial infarct size, preserving left-ventricular systolic function and reducing the onset of heart failure. Within minutes after the restoration of blood flow, however, reperfusion itself results in additional damage, also known as myocardial ischemia-reperfusion injury. An improved understanding of the pathophysiological mechanisms underlying reperfusion injury has resulted in the identification ofseveral promising pharmacological(cyclosporin-A, exenatide, glucose-insulin-potassium, atrial natriuretic peptide, adenosine, abciximab, erythropoietin, metoprolol and melatonin) therapeutic strategies for reducing the severity of myocardial reperfusion injury. Many of these agents have shown promise in initial proofof-principle clinical studies. In this article, we review the pathophysiology underlying myocardial reperfusion injury and highlight the potential pharmacological interventions which could be used in the future to prevent reperfusion injury and improve clinical outcomes in patients with coronary heart disease.

Qishen capsule safely boosts cardiac function and angiogenesis via the MEK/ERK pathway in a rat myocardial infarction model

Background Qishen(QS) capsules, a Traditional Chinese Medicine, has been widely used to treat coronary heart disease in China. However, evidence of its effectiveness remains unclear. Methods To explore whether QS has cardioprotective efficacy and/or promotes angiogenesis after myocardial infarction (MI), we performed experiments in a preclinical rat MI model. One month after left anterior descending coronary artery ligation, the rats received either QS solution (0.4 g/kg/day) or the same volume of saline by intragastric injection for four weeks. Results Echocardiographic and hemodynamic analyses demonstrated relatively preserved cardiac function in MI rats administered QS. Indeed, QS treatment was associated with reduced infarct scar size and heart weight index, and these beneficial effects were responsible for enhancing angiogenesis. Mechanistically, QS treatment increased phosphorylation of protein kinase B (Akt) and downregulated phosphorylation of mitogen-activated protein kinase/extracellular-regulated kinase (MEK/ERK). Conclusions QS therapy can improve the cardiac function of rats after MI by an underlying mechanism involving increased angiogenesis, at least partially via activation of the Akt signaling pathway and inhibition of MEK/ERK phosphorylation.

The epigenetic landscape of exercise in cardiac health and disease

With the rising incidence of cardiovascular diseases,the concomitant mortality and morbidity impose huge burdens on quality of life and societal costs.It is generally accepted that physical inactivity is one of the major risk factors for cardiac disease and that exercise benefits the heart in both physiological and pathologic conditions.However,the molecular mechanisms governing the cardioprotective effects exerted by exercise remain incompletely understood.Most recently,an increasing number of studies indicate the involvement of epigenetic modifications in the promotion of cardiac health and prevention of cardiac disease.Exercise and other lifestyle factors extensively induce epigenetic modifications,including DNA/RNA methylation,histone post-translational modifications,and non-coding RNAs in multiple tissues,which may contribute to their positive effects in human health and diseases.In addition,several studies have shown that maternal or paternal exercise prevents age-associated or high-fat dietinduced metabolic dysfunction in the offspring,reinforcing the importance of epigenetics in mediating the beneficial effects of exercise.It has been shown that exercise can directly modify cardiac epigenetics to promote cardiac health and protect the heart against various pathological processes,or it can modify epigenetics in other tissues,which reduces the risk of cardiac disease and affords cardioprotection through exerkines.An in-depth understanding of the epigenetic landscape of cardioprotective response to exercise will provide new therapeutic targets for cardiac diseases.This review,therefore,aimed to acquaint the cardiac community with the rapidly advancing and evolving field of exercise and epigenetics.

Late cardioprotection of exercise preconditioning against exhaustive exercise-induced myocardial injury by up-regulatation of connexin 43 expression in rat hearts

Objective: To investigate the expression of myocardium connexin 43(Cx43) in late exercise preconditioning(LEP) cardioprotection. Methods: Eight-week-old adult male Sprague Dawley rats were randomly assigned into four groups(n=8). Myocardial injury was judged in accordance with serum levels of c Tn and NT-pro BNP as well as hematoxylin basicfuchsin picric acid staining of myocardium. Cx43 m RNA was detected by in situ hybridization and qualified by real-time fluorescence quantitative PCR. Cx43 protein was localized by immunohistochemistry and its expression level was determined by western blotting. Results: The LEP obviously attenuated the myocardial ischemia/hypoxia injury caused by exhaustive exercise. There was no significant difference of Cx43 m RNA level between the four groups. Cx43 protein level was decreased significantly in group EE(P<0.05). However, LEP produced a significant increase in Cx43 protein level(P<0.05), and the decreased Cx43 protein level in exhaustive exercise was significantly up-regulated by LEP(P<0.05). Conclusions: LEP protects rat heart against exhaustive exercise-induced myocardial injury by up-regulating the expression of myocardial Cx43.

Protective effects of non-mitogenic human acidic fibroblast growth factor on hydrogen peroxide-induced damage to cardiomyocytes in vitro

AIM： To study the protective effect of non-mitogenic human acidic fibroblast growth factor （FGF） on cardiac oxidative injury in vivo. METHODS： Ventricular cardiomyocytes were isolated from 1- to 3-d-old neonatal SD mice and cultured in Dulbecco＇s minimum essential medium supplemented with 15% fetal bovine serum under an atmosphere of 50 mL/L CO2-95% air at 37℃, as well as assessed by immunooltochemical assay. We constructed the cardiomyoolte injury model by exposure to a certain concentration of H2O2. Cellular viability, superoxide dismutase （SOD） activity, leakage of maleic dialdehyde and anti-apoptosis effect were included to evaluate the cardiac protective effect of non-mitogenic human acidic FGF. RESULTS： Over 50% of the cardiomyocytes beat spontaneously on the 2nd d of culture and synchronously beat after being cultured for 3 d. Forty-eight hours after plating was completed, the purity of such cultures was 95% myocytes, assessed by an immunocytochemical assay. Cellular viability dramatically decreased with the increasing of the concentration of H2O2. Non-mitogenic human acidic FGF showed significant resistance to thetoxic effect of H2O2, significantly increased the cellular viability as well as the activity of SOD, and dramatically decreased the leakage of maleic dialdehyde as well as the cellular apoptosis rate. CONCLUSION： Hydrogen peroxide shows strong cytotoxicity to the cultured cardiac myocytes, and non-mitogenic human acidic FGF shows strong cardio-protective effect when exposed to a certain concentration of H2O2.

Effect of Xuebijing injection on myocardium during cardiopulmonary bypass:A prospective,randomized,double blind trial

BACKGROUND Cardiopulmonary bypass(CPB)is an essential procedure for maintaining the blood supply to vital organs in patients undergoing cardiac surgery.However,perioperative cardiac injury related to CPB remains a severe complication in these patients.Cardiac protection is important for patients undergoing CPB.AIM To evaluate the potential cardioprotective efficacy of the Chinese medicine preparation Xuebijing injection(XBJ)in patients undergoing CPB.METHODS Sixty patients undergoing cardiac surgery with CPB were randomly allocated to the XBJ and control groups(saline).XBJ was administered intravenously three times:12 h prior to surgery,at the beginning of the surgery,and 12 h after the second injection.Cardiac function was evaluated by echocardiography 48 h after surgery.Circulating inflammation-and oxidative-stress-related markers were measured.Clinical outcomes related to intensive care unit(ICU)stay were recorded.RESULTS Compared to control treatment,XBJ was associated with improved PaO2/FiO2 and cardiac systolic function,but reduced troponin I and creatine kinase fraction after surgery(all P<0.05).The circulating concentrations of tumor necrosis factor-α,interleukin(IL)-1βand IL-8 in the XBJ group were significantly lower than those in the control group(all P<0.05),whereas the circulating concentration of IL-10 was significantly higher in the XBJ group(P<0.05).In addition,the lengths of ICU stay and hospitalization after surgery tended to be shorter in the XBJ group than in the control group,although the differences were not significant.CONCLUSION Perioperative administration of XBJ was associated with attenuated cardiac injury during CPB,likely via anti-inflammatory and antioxidative mechanisms.

Cardio- and hepato-protective potential of methanolic extract of Syzygium cumini(L.) Skeels seeds:A diabetic rat model study

Objective: To evaluate the effect of methanolic extract of Syzygium cumini(L.) Skeels(S. cumini) seeds on the major organs in an animal model of diabetes through biochemical and histopathological studies.Methods: The methanolic extracts of S. cumini seeds(100 and 200 mg/kg body weight) were administered to alloxan-induced diabetic rats daily, with fasting blood glucose levels being measured by glucometry at one-day interval for a duration of two weeks. Biochemical assays to evaluate changes in the functions of the heart, liver,pancreas and kidney were carried out. Histopathological changes in the diabetic rat organs(pancreas, liver, heart, kidney and spleen) were also observed after the 14 days of treatment with the extracts.Results: Oral administration of methanolic extracts of S. cumini seeds(100 and 200 mg/kg body weight), with gliclazide as a positive control(25 mg/kg), showed beneficial effects including lowering blood glucose levels(P < 0.001), improved heart and liver functions, and hyperlipidemia due to diabetes. At 200 mg/kg, the extracts reversed cardiac and liver damage caused by alloxan.Conclusions: In addition to the anti-hyperglycemic activity of methanolic extracts of S. cumini seeds, the extracts demonstrates potential to minimize cardiac and hepatic complications.

Cardioprotective activity of alcoholic extract of Tinospora cordifolia (Willd.) Miers in calcium chloride-induced cardiac arrhythmia in rats

The present study investigated the antiarrhythmic activity of alcoholic extract of Tinospora cordifolia （T. cordifolia） in CaCl2 induced arrhythmia. CaCl2 （25 mg/kg） was administered by intravenous infusion （iv） to produce arrhythmia in rats. The animals were then treated with T. cordifolia extract （150, 250, and 450 mg/kg） and verapamil （5 mg/kg,iv）. Lead II electrocardiogram was monitored. Plasma calcium, sodium and potassium levels were measured. In CaCl2 induced arrhythmia, heart rate was decreased by 41.10%, T. cordifolia at 150, 300, and 450 mg/kg decreased the heart rate by 26.30%, 29.16%, and 38.29%, respectively, and verapamil reduced the heart rate by 9.70% compared to the normal group. The PQRST waves were normalized and atrial and ventricular fibrillation was controlled in rats treated with verapamil and T. cordifolia. CaCl2 increased calcium and sodium levels and decreased potassium levels in blood. T. cordifolia dose-dependently decreased calcium and sodium levels and increased potassium levels. Hence, T. cordifolia can be used in antiarrhythmic clinical settings and beneficial in atrial and ventricular fibrillation and flutter and may be indicated in ventricular tachyarrhythmia.

Involvement of adenosine and standardization of aqueous extract of garlic(Allium sativum Linn.)on cardioprotective and cardiodepressant properties in ischemic preconditioning and myocardial ischemia-reperfusion induced cardiac injury

The present study investigated the effect of garlic （Allium sativum Linn.） aqueous extracts on ischemic pre- conditioning and ischemia-reperfusion induced cardiac injury, as well as adenosine involvement in ischemic pre- conditioning and garlic extract induced cardioprotection. A model of ischemia-reperfusion injury was established using Langendorff apparatus. Aqueous extract of garlic dose was standardized （0.5%, 0.4%, 0.3%, 0.2%, 0.1%, 0.07%, 0.05%, 0.03%, 0,01%）, and the 0.05% dose was found to be the most effective. Higher doses （more than 0.05%） were highly toxic, causing arrhythmia and cardiodepression, whereas the lower doses were ineffective. Garlic exaggerated the cardioprotective effect of ischemic preconditioning. The cardioprotective effect of ischemic preconditioning and garlic cardioprotection was significantly attenuated by theophylline （1,000 ~tmol/L） and 8-SPT （10 mg/kg, i.p.） and expressed by increased myocardial infarct size, increased LDH level, and reduced nitrite and adenosine levels. These findings suggest that adenosine is involved in the pharmacological and molecular mechanism of garlic induced cardioprotection and mediated by the modulation of nitric oxide.

Effects of Metallothionein on Isolated Rat Heart

To investigate the effects of metallothionein （MT） on isolated rat heart, 16 Wistar rats were randomly divided into 2 groups. In control group （group C）, distilled water was injected intraperitoneally and 24 h later isolated hearts were perfused with Langendorff and stored at 4℃ for 3 h with histidine-tryptophan-ketoglutarate （HTK） solutions, and then isolated hearts were perfused for 2 h by Langendorff. In experimental group （group E）, 3.6% ZnSO4 was injected intraperitoneally, 24 h later isolated hearts were perfused by Langendorff and stored at 4℃ for 3 h with HTK solutions, and then the isolated hearts were perfused for 2 h with Langendorff. MT content, the recovery of hemodynamics, myocardial water content （MWC）, lactate dehydrogenase （LDH） and creatine kinase （CK） leakage, adenosine triphosphate （ATP） and malondialdehyde （MDA） content, superoxide dismutase （SOD） activity, myocardial cell Ca^2＋ content, Ca^2＋-ATPase activity of mitochondria （[Ca^2＋-ATPase]m） and its Ca^2＋ content （[Ca^2＋]m）, synthesizing ATP activity of mitochondria （[ATP]m）, and the ultrastructure of cells were examined. There were a significant increase in group E in hemodynamic recovery, ATP content, SOD activity, [Ca^2＋-ATPase]m activity, [ATP]m activity, and substantial reduction in MWC, LDH and CK leakage, MDA content, myocardial cell Ca^2＋ content, [Ca^2＋]m content, and the ultrastructural injury were obviously milder than that of group C. This study demonstrated that MT has protective effects on isolated rat heart.

Pharmacological aspects of fisetin

Over the past decades,epidemiological studies have concluded that a diet rich in plant-derived products plays a pivotal role in human health.Fisetin(3,3’,4’,7-tetrahydroxyflavone)is a hydrophobic polyphenolic compound primarily found in edible plants(e.g.strawberry,blueberry,apple,grape,persimmon,kiwi,and cucumber).Various preclinical studies have revealed that fisetin exhibits a wide range of pharmacological effects such as antioxidant,antiinflammatory,anti-carcinogenic,anti-osteoporotic,antimicrobial,and anti-diabetic properties.Therefore,the pharmacological in vitro and in vivo studies on fisetin are discussed in this review.Additionally,this review would be useful for further study regarding the potential of natural products,notably fisetin,and its therapeutic potential for the prevention and treatment of diseases.

Weight losing, antihyperlipidemic and cardioprotective effects of the alkaloid fraction of Hunteria umbellata seed extract on normal and triton-induced hyperlipidemic rats

Objective: To investigate the weight losing, antihyperlipidemic and cardioprotective effects of the alkaloid fraction of Hunteria umbellata(H. umbellata) seed.Methods: Adult female Wistar rats(weight range: 120-150 g) were randomly divided into 4 and 5 treatment groups in the normal and triton-induced hyperlipidemic models, respectively. and were daily treated for 14 d before they were humanely sacrificed under inhaled diethyl ether anesthesia. About 5 mL of whole blood was obtained by cardiac puncture from each treated rat, from which serum for lipids assay was subsequently separated. Tissue samples of livers of treated rats were harvested and processed for histopathological analysis.Results: Repeated daily oral treatments of normal rats with 25 and 50 mg/kg/day of alkaloid fraction of H. umbellata resulted in significant(P<0.05 and P<0.001) and dose-dependent weight loss, and decreases in the serum triglyceride, total cholesterol and low density lipoprotein cholesterol, while significantly(P<0.001) increased the serum levels of high density lipoprotein cholesterol fraction. Similarly, oral pre-treatments with 25 and 50 mg/kg/day of alkaloid fraction of H. umbellata for 14 d before induction of hyperlipidemia with triton WR-1339 significantly(P<0.01, P<0.001) and dose-dependently attenuated increases in the average body weights, serum levels of triglyceride, total cholesterol and low density lipoprotein cholesterol while also significantly(P<0.01, P<0.001) and dose-dependently attenuated significant(P<0.001) decrease in the serum high-density lipoproteincholesterol levels when compared to the untreated control values. However, the results obtained for 50 mg/kg of alkaloid fraction of H. umbellata in both normal and triton WR-1339-induced hyperlipidemic rats were comparable to that recorded for 20 mg/kg of simvastatin. Similarly, oral pretreatments with 25 and 50 mg/kg/day of alkaloid fraction of H. umbellata significantly improved the histological lesions of fatty hepatic degeneration induced by triton WR-1339 treatment.Conclusions: Overall, results of this study showed that repeated oral treatments with 25 and 50 mg/kg/day of alkaloid fraction of H. umbellata elicited weight losing, antihyperlipidemic and cardioprotective effects in triton WR-1339 induced hyperlipidemic rats that were mediated via de novo cholesterol biosynthesis inhibition.

YiQiFuMai powder injection attenuates ischemia/reperfusion-induced myocardial apoptosis through AMPK activation

The YiQiFuMai powder injection （ YQFM）, a Traditional Chinese Medicine （TCM） prescription re-de- veloped based on the well-known TCM formula Sheng-maisan, showed a wide range of pharmacological activities in cardiovascular diseases in clinic. However, its role in protection against myocardial ischemia/reperfusion （MI/R） injury has not been elucidated. The present study not only evaluated the eardioprotective effect of YQFM from MI/ R injury but also investigated the potential molecular mechanisms in vivo and in vitro. The mouse model of MI/R injury was induced by a transient vessel occlusion for 30 rain and reperfusion for 24 h. The myocardium infarct size, production of lactate dehydrogenase （LDH）, creatine kinase （CK）, TUNEL staining and easpase-3 activity were measured. AMPKeα and phospho-AMPKα was analyzed by Western blot. We further verified the protective effect and potential molecular mechanisms of YQFM in an in vitro model of simulated ischemia and reperfusion （ SI/ R） in H9c2 cardiomyocytes. Cell viability was determined, and cell apoptosis were measured by Hoechst 33342 staining and Flow cytometry. Mitochondrial membrane potential （△ψFm） was measured, and ATP content was quantified by biolumineseent assay. Expression of apoptosis-related proteins including Caspase-3, Bcl-2, Bax, AMPKα and phospho-AMPKα was analyzed by Western blot. AMPKoL siRNA transfection was also applied to the mechanism elucidation. YQFM significantly reduced myocardium infarct size and the production of LDH, CK in se- rum, and also produced a significant decrease of apoptotic index which was confirmed by TUNEL staining and the changes of caspase-3 activity. In addition, pretreatment with YQFM markedly improved cell viability and decreased LDH release. Moreover, YQFM inhibited H9c2 apoptosis, blocked the expression of easpase-3 and modulated Bcl- 2 and Bax proteins, leading to an increased mitochondrial membrane potential and cellular ATP content. Mechanis- tically, YQFM activated AMPK signaling pathways while pretreatment with AMPK inhibitor compound C and appli- cation of transfection with AMPKα siRNA attenuated the anti-apoptotie effect of YQFM. Our results indicated that YQFM could provide significant cardioproteetion against MI/R injury, and potential mechanisms might to suppres- sion of cardiomyocytes apoptosis at least in part through activating the AMPK signaling pathways.

Cardioprotective effect of Urena lobataleaves extract on diabetic rats

OBJECTIVE To know cardioprotective effect of U.lobataleaves extract on diabetic rat.METHODS This study uses control group post test only with male sprague dawley rats.Diabetic rats was induced by high fructose diet(HFD)and single dose streptozotocin 25mg·kg-1 bw intra peritoneal.The rat was administrated orally with water extract of U.lobataleaves in concentrations of 250,500 and 1000mg·kg-1 bw for 4 weeks.After scarifying,heart organ were collected and then superoxyde dismutase(SOD)heart level,malondialdehyda(MDA)and tumor necrosis factor-alpha(TNF-α)were examined.The data was analyzed using ANOVA test continued with LSD test(P<0.05).RESULTS The oral administration of U.lobataleaves extract 250,500,and 1000mg·kg-1 bw were able to increase SOD heart level about 40%,50% and 70% respectively compared to diabetic group(P<0.05),while the MDA heart level was decreased by 60%,90% and 110%(P<0.05)respectively.The supplementation of water extract from U.lobatain dose of 250,500 and 1000mg·kg-1 bw were also decrease TNF-αheart level approximately 20%,40% and 60% compared to control group(P<0.05).In diabetic groups,SOD heart level was decreased compared to normal group(P<0.05)while the MDA and TNF-αwere increased(P<0.05).CONCLUSION U.lobataleaves extract acts as cardioprotector on diabetic rats by increasing of SOD heart level,decreasing of MDA heart level and TNF-α.This effect may be related to active compounds that act as an antioxidant and anti-inflammatory in U.lobata extract.

Cardioprotective Effects of Diazoxide on Myocardial Ischemia/Reperfusion Injury in Rats

In order to study the cardioprotective effects of diazoxide on the myocardial ischemia/reperfusion injury of rats and mechanisms, the healthy SD rats were randomly divided into 2 groups： the rats in the experimental group were injected with diazoxide for preconditioning with the dosage of 12.5 mg/kg through the right femoral vein and those in the control group was only administered with the equal volume of media. After 10 rain, a left thoracotomy was performed and the left anterior descending branch was occluded for 2 h. Two h later, the left anterior descending branch was reperfused for 2 h and then the heart was quickly excised to be used for measurement of MDA, SOD and the infarct size, in situ cell apoptosis detection and observation of the cell ultrastructure by electron microscopy. The results showed that as compared with the control group, MDA, the infarct size and cell apoptosis in the experimental group were greatly reduced （P〈0.05）. And the cell ultrastructure was obviously improved, But the activity of SOD had no change （P〉0.05）. It was concluded that diazoxide could protect the rats from myocardial ischemia/reperfusion injury, which might be contributed to the reduction of lipid peroxidation and cell apoptosis.

Effects of Diazoxide Treatments on Electrophysiologyic Properties in Guinea Pig Papillary Muscles Undergoing Ischemia/Reperfusion

The effects of diazoxide treatments on electrophysiologyic properties in guinea pig papillary muscles undergoing ischemia/reperfusion was studied using intracellular microelectrode technique. Twenty-four guinea pigs were randomly divided into three groups (n=8 in each group). In control group, St.Thomas solution was given. In experimental group, St.Thomas solution with diazoxide (100 mol/L) was given. In pretreatment group, the muscle was treated with diazoxide 20 min before arrested with St.Thomas cardioplegia. The results showed that the APD_50 and APD_90 in experimental and pretreatment groups were significantly shorter after 5 and 10 min reperfusion (P<0.01, P<0.05), but longer after 30 min reperfusion (P<0.01, P<0.05) than in control group. In experimental and pretreatment groups, APA, OS, Vmax recovered more quickly than those in control group. The time to re-systole after reperfusion in control group was longer than that in experimental and pretreatment groups. There was no significant difference in RP among three groups. The time of arrest in pretreatment group was longer than that in experimental and pretreatment group (P<0.05). This study indicates that protective effects of St.Thomas solution with diazoxide is better than that of pretreatment with diazoxide or St.Thomas solution alone.