激动乙醛脱氢酶2对抗糖尿病大鼠心肌缺血/再灌注损伤的作用

目的:探讨激动乙醛脱氢酶2(ALDH2)在糖尿病大鼠心肌损伤中的作用。方法:腹腔注射55 mg/kg链脲佐菌素复制糖尿病大鼠模型,分为糖尿病组和乙醇+糖尿病组(n=8)。8周后行离体心肌缺血/再灌注(I/R),测定心室动力学指标和复灌期间冠脉流出液中乳酸脱氢酶(LDH)含量。测定空腹血糖、糖化血红蛋白(HbA1c)水平。RT-PCR和Western blot测定左心室前壁心尖组织线粒体ALDH2 mRNA和蛋白表达。结果:与正常大鼠心肌I/R相比,糖尿病大鼠左室发展压、左心室最大上升和下降速率、左室做功进一步下降,左室舒张末压抬高,复灌期冠脉流出液中LDH释放增多,心室ALDH2 mRNA和蛋白表达降低;与糖尿病大鼠心肌I/R相比,ALDH2激动剂乙醇明显促进左室发展压、左心室最大上升和下降速率、左室做功的恢复,降低左室舒张末压,同时降低HbA1c水平和LDH的释放,ALDH2 mRNA和蛋白表达增高。结论:糖尿病大鼠心肌缺血/再灌注时,心肌ALDH2表达降低;增强ALDH2在糖尿病大鼠心肌中的表达可发挥保护作用。     

雌激素对去卵巢大鼠离体心脏缺血／再灌注损伤的保护作用

目的：探讨雌激素对去卵巢大鼠离体心脏缺血／再灌注损伤的保护作用。方法：成年SD雌鼠,随机分为假手术组（Sham）,双侧卵巢切除组（Ovx）和双侧卵巢切除后补充17β-雌二醇组（Ovx＋E2）。各组离体心脏再随机分为不同时间的缺血再灌注亚组。测量的指标包括冠脉流出液中LDH及CK含量、心室肌细胞存活率及产率、基础状态和异丙肾上腺素（ISO）刺激状态下收缩幅度。结果：30min缺血及其各复灌纽均显著增加冠脉流出液中LDH、CK的释放量。Ovx组LDH、CK漏出在30min缺血及再灌注条件下,显著高于正常灌注组,而Ovx＋E2组可减轻心肌损伤,减少LDH、CK的释放。10min和20min缺血对心肌细胞存活率、产率及冠脉流出液中LDH、CK含量影响均不明显。Sham、Ovx、Ovx＋E2各组心肌细胞基础收缩幅度在正常和10minⅠ＋30minR灌注条件下无显著差异。Ovx显著增加其他各组心肌细胞基础收缩和ISO刺激收缩幅度,Ovx＋E2可使其降至Sham水平。结论：雌激素对去卵巢大鼠心肌缺血／再灌注损伤具有保护作用。     

雷米普利对糖尿病大鼠心肌缺血／再灌注损伤保护作用的超微结构研究

目的：研究雷米普利对糖尿病大鼠心肌缺血／再灌注损伤的保护作用,并从超微结构的角度初步探讨其作用机制。方法：链脲佐菌素致糖尿病大鼠被随机分为3组（n=16）：缺血／再灌注（I／R）、缺血预适应（IPC）和雷米普利（RAM）组。RAM组每天用雷米普利（1mg／kg）灌胃,I／R和IPC组用等体积生理盐水灌胃。4周后各组动物均经历心肌缺血／再灌注损伤,IPC组于缺血前行心肌缺血预适应。连续监测心电图变化,测定心肌梗死面积,光、电镜下观察心肌形态学改变。结果：与I／R组比较,RAM及IPC组缺血期心脏ST-段抬高幅度降低,室早出现时间推迟,持续时间缩短,室速、室颤发生率降低,心肌梗死面积缩小,形态学观察心肌损伤减轻,心肌纤维及线粒体特征性结构保持清晰,血管通畅,内皮损伤减轻。结论：连续4周使用RAM对实验性糖尿病大鼠具有与IPC相似的心脏保护效应,机制可能与保护心肌细胞及线粒体、改善内皮功能等有关。     

Zinc and myocardial ischemia/reperfusion injury

As an important trace element, zinc is required for the normal cellular structure and function, and impairment of zinc homeostasis is associated with a variety of health problems including cardiovascular disease. Zinc homeostasis is regulated through zinc transporters, zinc binding molecules, and zinc sensors. Zinc also plays a critical role in cellular signaling. Studies have documented that zinc homeostasis is impaired by ischemia/reperfusion in the heart and zinc dyshomeostasis may play a role in the pathogenesis of myocardial ischemia/reperfusion injury. Both exogenous and endogenously released zinc may play an important role in cardioprotection against ischemia/reperfusion injury. The goal of this review is to summarize the current understanding of the roles of zinc homeostasis and zinc signaling in myocardial ischemia/reperfusion injury.     

Anti-apoptotic effect of magnolol in myocardial ischemia and reperfusion injury requires extracellular signal-regulated kinase1/2 pathways in rat in vivo

Magnolol, an active component extracted from Magnolia officinalis, has been reported to have protective effect on ischemia and reperfusion (I/R)-induced injury in experimental animals. The aim of the present investigation was to further evaluate the mechanism(s) by which magnolol reduces I/R-induced myocardial injury in rats in vivo. Under anesthesia, left anterior descending (LAD) coronary artery was occluded for 30 min followed by reperfusion for 24 h (for infarct size and cardiac function analysis). In some experiments, reperfusion was limited to 1 h or 6 h for analysis of biochemical and molecular events. Magnolol and DMSO solution (vehicle) were injected intra-peritoneally 1 h prior to I/R insult. The infarct size was measured by TTC technique and heart function was monitored by Millar Catheter. Apoptosis related events such as p-ERK, p-Bad, Bcl-xl and cytochrome c expression were evaluated by Western blot analysis and myocardial caspase-3 activity was also measured. Magnolol (10 mg/kg) reduced infarct size by 50% (P < 0.01 versus vehicle), and also improved I/R-induced myocardial dysfunction. Left ventricular systolic pressure and positive and negative maximal values of the first derivative of left ventricular pressure (dP/dt) were significantly improved in magnolol-treated rats. Magnolol increased the expression of phosphor ERK and Bad which resulted in inhibition of myocardial apoptosis as evidenced by TUNEL analysis and DNA laddering experiments. Application of PD 98059, a selective MEK1/2 inhibitor, strongly antagonized the effect of magnolol. Taken together, we concluded that magnolol inhibits apoptosis through enhancing the activation of ERK1/2 and modulation of the Bcl-xl proteins which brings about reduction of infarct size and improvement of cardiac function in I/R-induced injury.     

The role of C-reactive protein in ischemia/reperfusion injury and preconditioning in a rat model of myocardial infarction

For the first time the involvement of C-Reactive protein (CRP) in early (acute) and delayed ischemic (IPC) and pharmacological (chemical) preconditioning (CPC) in an in vivo model of rat myocardial infarction was presented. Acute IPC was produced by three 5 minute occlusion (ischemia) periods interspersed with 5 minute reperfusion, followed by 30 minute occlusion of the left coronary artery and 2 hour reperfusion injury. Acute CPC was produced by a k-opioid receptor agonist U50488H (5 mg/kg) applied i.v. 15 minutes before 30 minute ischemia/ 2 hour reperfusion. Delayed preconditioning was produced by 30 minute ischemia/ 2 hour reperfusion, induced 24 hour after either ischemic or pharmacological preconditioning. The myocardial ischemia/reperfusion injury was evaluated on the basis of total and cardiac creatine kinase isoenzyme activity, functional recovery of the heart (ECG), infarct size (% IS/RA) and mortality at the end of the experiments. The results obtained showed that: k-opioid receptor agonist U50488H mimics both the acute and delayed IPC in the above experimental protocol; Both acute IPC and most probably CPC act by opening of K(ATP) channels (the effects were blocked by nonspecific ATP-sensitive K channel blocker glybenclamide), and via activation of protein kinase C (a selective protein kinase C inhibitor chelerythrine blocked the efects); C-reactive protein (CRP) was significantly elevated by 54% in non-preconditioned acute ischemia/reperfusion injury. The elevation was more pronounced (82% increase) 24 hour after non-preconditioned ischemia/reperfusion injury. It reflected very well the increase in cardiac isoenzymes, infarct size and mortality of the rats, and can be used as a marker of the severity of myocardial injury in this model; The increase of CRP was prevented by both IPC and CPC in early, and especially in late preconditioning. This confirms the involvement of CRP as a marker in cardiac ischemic/reperfusion injury. It was concluded that in addition to the established involvement of adenosine, bradykinin, opioid and other receptors, a suppression of myocardial CRP/complement production might be involved in the biological mechanism of preconditioning. This could be a promising perspective in clinical interventions against ischemia/reperfusion injuries of the heart.     

Hyperlipidemia does not prevent the cardioprotection by postconditioning against myocardial ischemia/reperfusion injury and the involvement of hypoxia inducible factor-1α upregulation

Hyperlipidemia is regarded as an independent risk factor in the development of ischemic heart disease, and it can increase the myocardial susceptibility to ischemia/reperfusion （I/R） injury, lschemic postconditioning （Postcon） has been demonstrated to attenuate the myocardial injury induced by I/R in normal conditions. But the effect of ischemic Postcon on hyperlipidemic animals is unknown. Hypoxia inducible factor-1 （HIF-1） has been demonstrated to play a central role in the cardioprotection by preconditioning, which is one of the protective strategies except for Postcon. The aim of this study was to determine whether Postcon could reduce myocardial injury in hyperlipidemic animals and to assess whether HIF-1 was involved in Postcon mechanisms. Male Wistar rats underwent the left anterior descending coronary occlusion for 30 min followed by 180min of reperfusion with or without Postcon after fed with high fat diet or normal diet for 8 weeks. The detrimental indices induced by the I/R insult included infarct size, plasma creatine kinase activity and caspase-3 activity. Results showed that hyperlipidemia remarkably enhanced the myocardial injury induced by I/R, while Postcon significantly decreased the myocardial injury in both normolipidemie and hyperlipidemic rats. Moreover, both hyperlipidemia and I/R promoted the HIF-αL expression. Most importantly, we have for the first time demonstrated that Postcon further induced a significant increase in HIF-αL protein level not only in normolipidemie but also in hyperlipidemic conditions. Thus, Postcon reduces the myocardial injury induced by I/R in normal and hyperlipidemic animals, and HIF-αL upregulation may involve in the Postcon-mediated cardioprotective mechanisms.     

Roles of mitochondrial Src tyrosine kinase and zinc in nitric oxide-induced cardioprotection against ischemia/reperfusion injury

Abstract

While nitric oxide (NO) induces cardioprotection by targeting the mitochondrial permeability transition pore (mPTP), the precise mitochondrial signaling events that mediate the action of NO remain unclear. The purpose of this study was to test whether NO induces cardioprotection against ischemia/reperfusion by inhibiting oxidative stress through mitochondrial zinc and Src tyrosine kinase. The NO donor S-nitroso-N-acetyl penicillamine (SNAP) given before the onset of ischemia reduced cell death in rat cardiomyocytes subjected to simulated ischemia/reperfusion, and this was abolished by the zinc chelator N,N,N’,N’-tetrakis-(2-pyridylmethyl)ethylenediamine (TPEN) and the Src tyrosine kinase inhibitor PP2. SNAP also prevented loss of mitochondrial membrane potential (ΔΨm) at reperfusion, an effect that was blocked by TPEN and PP2. SNAP increased mitochondrion-free zinc upon reperfusion and enhanced mitochondrial Src phosphorylation in a zinc-dependent manner. SNAP inhibited both mitochondrial complex I activity and mitochondrial reactive oxygen species (ROS) generation at reperfusion through zinc and Src tyrosine kinase. Finally, the anti-infarct effect of SNAP was abrogated by TPEN and PP2 applied at reperfusion in isolated rat hearts. In conclusion, NO induces cardioprotection at reperfusion by targeting mitochondria through attenuation of oxidative stress resulted from the inhibition of complex I at reperfusion. Activation of mitochondrial Src tyrosine kinase by zinc may account for the inhibition of complex I.     

Pyrrolidinyl caffeamide against ischemia/reperfusion injury in cardiomyocytes through AMPK/AKT pathways

Background

Coronary heart disease is a leading cause of death in the world and therapy to reduce injury is still needed. The uncoupling of glycolysis and glucose oxidation induces lactate accumulation during myocardial ischemia/reperfusion (I/R) injury. Cell death occurs and finally leads to myocardial infarction. Caffeic acid, one of the major phenolic constituents in nature, acts as an antioxidant. Pyrrolidinyl caffeamide (PLCA), a new derivative of caffeic acid, was synthesized by our team. We aimed to investigate the effect of PLCA on hypoxia/reoxygenation (H/R) in neonatal rat ventricular myocytes (NRVM) and on myocardial I/R in rats.

Results

Cardiomyocytes were isolated and subjected to 6 h hypoxia followed by 18 h reperfusion. PLCA (0.1 to 3 μM) and metformin (30 μM) were added before hypoxia was initiated. PLCA at 1 μM and metformin at 30 μM exerted similar effects on the improvement of cell viability and the alleviation of cell apoptosis in NRVM after H/R. PLCA promoted p-AMPK, p-AKT, and GLUT4 upregulation to induce a cardioprotective effect in both cell and animal model. The accumulation of cardiac lactate was attenuated by PLCA during myocardial I/R, and infarct size was smaller in rats treated with PLCA (1 mg/kg) than in those treated with caffeic acid (1 mg/kg).

Conclusions

AMPK and AKT are synergistically activated by PLCA, which lead facilities glucose utilization, thereby attenuating lactate accumulation and cell death. The cardioprotective dose of PLCA was lower than those of metformin and caffeic acid. We provide a new insight into this potential drug for the treatment of myocardial I/R injury.     

Pyruvate provides cardioprotection in the experimental model of myocardial ischemic reperfusion injury

The present study was designed to evaluate the cardioprotective potential of pyruvate and to characterize the mechanism underlying the protection. Wistar albino rats were randomly divided into three groups. Two groups were administered saline orally (sham, ischemia-reperfusion (I-R) control group) and animals of third group received pyruvate (500 mg/kg) for 4 weeks. On the 29th day, animals of the I-R control and pyruvate treated groups underwent 45 min of occlusion of the left anterior descending (LAD) coronary artery and were thereafter reperfused for 60 min. In the I-R control group, a significant cardiac necrosis, depressed mean arterial pressure (MAP) and heart rate (HR), decline in myocardial antioxidant status and elevation in lipid peroxidation were observed as compared to sham control. Pyruvate treatment restored the myocardial antioxidant status and favorably modulated the altered MAP as compared to I-R control. Furthermore, I/R-induced lipid peroxidation was significantly inhibited by pyruvate treatment. These beneficial cardioprotective effects translated into significant improvement in MAP. Histopathological examination and restored specific myocardial injury marker CK-MB isoenzyme activity further confirmed protective effects of pyruvate. In conclusion, our study has demonstrated that the beneficial effect of pyruvate likely results from improved MAP and suppression of oxidative stress.     

Daidzein administration in vivo reduces myocardial injury in a rat ischemia/reperfusion model by inhibiting NF-kB activation

AimsWe tested the hypothesis that daidzein may reduce myocardial damage by both inhibiting the release of cytokines and limiting the nuclear translocation of NF-kB.Main methodsMale Sprague–Dawley rats were anesthetized, and the left anterior descending coronary artery (LAD) was ligated for 25 min. Twenty-four hours after reperfusion was established, the hemodynamics and infarct size were examined.Key findingsTreatment with daidzein (10 mg/kg, i.p.) 1 h prior to the ischemia/reperfusion procedure (I/R) reduced the infarct size by 52.8% (P < 0.05). Daidzein also significantly improved I/R-induced myocardial contractile dysfunction by improving the left ventricular diastolic pressure and the positive and negative maximal values of the first derivative of the left ventricular pressure. In addition, daidzein reduced the plasma levels of TNF-α and IL-6 in I/R rats and decreased malondialdehyde levels, myeloperoxidase activity, catalase activity and neutrophil infiltration in I/R rat myocardium. Interestingly, daidzein inhibited I/R-induced myocardial apoptosis by decreasing DNA strand breaks and cleaved caspase-3 activity. Furthermore, daidzein inhibited both the nuclear translocation of NF-kB in I/R rat hearts and the H₂O₂-induced activation of NF-kB-luciferase activity in human umbilical vein endothelial cells.SignificanceThis study reveals that the administration of daidzein in vivo attenuates I/R-induced myocardial damage via inhibition of NF-kB activation, which in turn may suppress inflammatory cytokine expression.     

Inhibition of endoplasmic reticulum stress by neuregulin-1 protects against myocardial ischemia/reperfusion injury

Neuregulin-1 (NRG-1), an endogenously produced polypeptide, is the ligand of cardiomyocyte ErbB receptors, with cardiovascular protective effects. In the present study, we explored whether the cardioprotective effect of NRG-1 against I/R injury is mediated by inhibiting myocardial endoplasmic reticulum (ER) stress. In vitro, NRG-1 directly inhibited the upregulation of ER stress markers such as glucose-regulated protein 78, CCAAT/enhancer binding protein homologous protein and cleaved caspase-12 induced by the ER stress inducers tunicamycin or dithiothreitol in both neonatal and adult ventricular myocytes. Attenuating ErbB signals by an ErbB inhibitor AG1478 or ErbB4 knockdown and preincubation with phosphoinositide 3-kinase inhibitors all reversed the effect of NRG-1 inhibiting ER stress in cultured neonatal rat cardiomyocytes. Concurrently, cardiomyocyte ER stress and apoptosis induced by hypoxia-reoxygenation were decreased by NRG-1 treatment in vitro. Furthermore, in an in vivo rat model of myocardium ischemia/reperfusion (I/R), intravenous NRG-1 administration significantly decreased ER stress and myocardial infarct size induced by I/R. NRG-1 could protect the heart against I/R injury by inhibiting myocardial ER stress, which might be mediated by the phosphoinositide 3-kinase/Akt signaling pathway.     

Protective effect of ginsenoside Rb1 against myocardial ischemia/reperfusion injury in streptozotocin-induced diabetic rats

The objective of the current study is to investigate whether ginsenoside Rb1, a major pharmacological extract of ginseng that could attenuate myocardial ischemia reperfusion (MI/R) injury in non-diabetic myocardium, can attenuate MI/R injury in diabetes that are more vulnerable to ischemic insult. Rats were divided into seven groups: (i) diabetic sham, (ii) diabetic, (iii) normal, (iv) diabetic + ginsenoside Rb1, (v) diabetic + wortmannin, (vi) diabetic + wortmannin + ginsenoside Rb1, (vii) diabetic sham + wortmannin. Ginsenoside Rb1 and/or wortmannin were administered prior to inducing MI/R (30 min of coronary artery occlusion followed by 120 min reperfusion). At the end of the experiment, postischemic myocardial infarct size was significantly higher in the diabetic untreated group as compared to normal (P < 0.05), accompanied with increased myocardial apoptosis, elevated plasma CK-MB and LDH release and reduced blood pressure. Ginsenoside Rb1 reduced infarct size, cardiomyocyte apoptosis and caspase-3 activity compared to the diabetic group. The cardioprotective effects of ginsenoside Rb1 were cancelled by wortmannin. Ginsenoside Rb1 significantly upregulated phosphorylated Akt expression, which was attenuated by wortmannin. Ginsenoside Rb1 exerts cardioprotective effects against MI/R injury in diabetic rats, which is partly through activation of phosphatidylinositol 3-kinase (PI3 K)/Akt pathway. Thus this study shows a novel pharmacological preconditioning with ginsenoside Rb1 in the diabetic myocardium.     

白藜芦醇甙对大鼠心脏缺血/再灌注损伤的保护作用

本文利用冠脉结扎/放松方法和Langendorff灌注技术,建立在体和离体大鼠心脏缺血/再灌注(ischemia/reperfusion,I/R)损伤模型,探讨白藜芦醇甙(polydatin)对大鼠I/R心肌损伤的保护作用及其机制.观察白藜芦醇甙对缺血和再灌注心律失常、心肌梗死面积、心脏收缩功能、心肌超氧化物歧化酶(superoxide dismutase,SOD)活性、丙二醛(malondialdehyde,MDA)含量、NO含量以及一氧化氮合酶(nitric oxide synthase,NOS)活性的影响.结果显示:与对照组相比,白藜芦醇甙组大鼠缺血和再灌注心律失常明显降低(P<0.05,P<0.01);心肌梗死面积显著减少(P相似文献   

C5a inhibitor protects against ischemia/reperfusion injury in rat small intestine

Acute mesenteric ischemia (AMI) is caused by considerable intestinal injury, which is associated with intestinal ischemia followed by reperfusion. To elucidate the mechanisms of ischemia/reperfusion injuries, a C5a inhibitory peptide termed AcPepA was used to examine the role of C5a anaphylatoxin, induction of inflammatory cells, and cell proliferation of the intestinal epithelial cells in an experimental AMI model. In this rat model, the superior mesenteric artery was occluded and subsequently reperfused (Induce‐I/R). Other groups were treated with AcPepA before ischemia or reperfusion. Induce‐I/R induced injuries in the intestine and AcPepA significantly decreased the proportion of severely injured villi. Induce‐I/R induced secondary receptor for C5a‐positive polymorphonuclear leukocytes in the vessels and CD204‐positive macrophages near the injured site; this was correlated with hypoxia‐induced factor 1‐alpha‐positive cells. Induction of these inflammatory cells was attenuated by AcPepA. In addition, AcPepA increased proliferation of epithelial cells in the villi, possibly preventing further damage. Therefore, Induce‐I/R activates C5a followed by the accumulation of polymorphonuclear leukocyte and hypoxia‐induced factor 1‐alpha‐producing macrophages, leading to villus injury. AcPepA, a C5a inhibitory peptide, blocks the deleterious effects of C5a, indicating it has a therapeutic effect on the inflammatory consequences of experimental AMI.     

Selenium protects the immature rat heart against ischemia/reperfusion injury

The aim of the study was to find out whether administration of selenium (Se) will protect the immature heart against ischemia/reperfusion. The control pregnant rats were fed laboratory diet (0.237 mg Se/kg diet); experimental rats received 2 ppm Na₂SeO₃ in the drinking water from the first day of pregnancy until day 10 post partum. The concentration of Se in the serum and heart tissue was determined by activation analysis, the serum concentration of NO by chemiluminescence, cardiac concentration of lipofuscin-like pigment by fluorescence analysis. The 10 day-old hearts were perfused (Langendorff); recovery of developed force (DF) was measured after 40 min of global ischemia. In acute experiments, 10 day-old hearts were perfused with selenium (75 nmol/l) before or after global ischemia. Sensitivity to isoproterenol (ISO, pD₅₀) was assessed as a response of DF to increasing cumulative dose. Se supplementation elevated serum concentration of Se by 16%. Se increased ischemic tolerance (recovery of DF, 32.28 ± 2.37 vs. 41.82 ± 2.91%, P < 0.05). Similar results were obtained after acute administration of Se during post-ischemic reperfusion (32.28 ± 2.37 vs. 49.73 ± 4.40%, P < 0.01). The pre-ischemic treatment, however, attenuated the recovery (23.08 ± 3.04 vs. 32.28 ± 2.37%, P < 0.05). Moreover, Se supplementation increased the sensitivity to the inotropic effect of ISO, decreased cardiac concentration of lipofuscin-like pigment and serum concentration of NO. Our results suggest that Se protects the immature heart against ischemia/reperfusion injury. It seems therefore, that ROS may affect the function of the neonatal heart, similarly as in adults.