Peroxynitrite in myocardial ischemia-reperfusion injury

Peroxynitrite is a highly reactive oxidant which is produced during reperfusion of the ischemic heart. The role that this molecule plays in reperfusion injury has been controversial. Many investigations have demonstrated toxic effects of peroxynitrite, whereas others have found it to be protective during reperfusion. This review surveys evidence supporting both sides and proposes that peroxynitrite is a dichotomous molecule with beneficial and detrimental effects on the reperfused heart. Its toxic effects are mediated by modification and activation of a variety of targets (including poly (ADP) ribose synthetase and matrix metalloproteinases) while its beneficial effects are primarily mediated through its reaction with thiols, resulting in the formation of NO donor compounds (S-nitrosothiols).     

MicroRNAs与心肌缺血再灌注损伤

MicroRNAs（miRNAs）是一类高度保守的非编码小分子RNA,经转录后调节细胞的增殖、迁移、分化、凋亡和免疫应答等。miRNAs与心血管疾病发生发展密切相关。心肌缺血后多种miRNA。异常表达,它们在介导心肌缺血再灌注损伤和调控心肌缺血保护环节中起重要作用,可作为诊断缺血再灌注损伤的标志物和潜在治疗靶点。     

Polyamine metabolism in rat myocardial ischemia-reperfusion injury

This study was focused on investigating the involvement of polyamine metabolism in the myocardial ischemia-reperfusion injury (MIRI) in an in vivo rat model. A branch of the descending left coronary artery was occluded for 30 min followed by 2 h, 6 h, 12 h, and 24 h reperfusion. Then the expression of spermidine/spermine N1-acetyltransferase (SSAT) and ornithine decarboxylase (ODC) and the concentrations of polyamines were assessed. It was found that the expression of SSAT and ODC were upregulated after reperfusion and the concentrations of spermidine and spermine were significantly decreased, while putrescine concentration was significantly increased. The results suggest that MIRI may cause disturbance of polyamine metabolism, and it may play a critical role in MIRI.     

氧化应激与心肌细胞缺血再灌注损伤

冠状动脉粥样硬化性心脏病血运重建治疗是挽救缺血心肌的重要治疗方式。但血流恢复本身会引起缺血再灌注损伤,氧化还原失衡是缺血再灌注损伤发生的重要起始因素。心肌细胞各结构参与氧化应激反应的发生。细胞膜结构中富集Caveolin-1的质膜微囊影响NADPH氧化酶的组装、移位和ROS介导的信号转导参与缺血再灌注中氧化还原反应的发生。由复合物I、II、III、IV及电子载体组成的线粒体电子传递链在缺氧-复氧过程中遭到破坏导致电子传递受阻,线粒体膜通透性转换孔持续开放,是细胞中氧自由基过量产生的重要来源。细胞核及线粒体中核酸分子损伤影响结构蛋白正常合成,细胞氧化还原平衡代谢受损,此外位于细胞核中的肌球蛋白还可以作为一种核转录因子调控NOX2的表达,增加氧自由基的合成。JNK、p38MAPK、Egr-1、NF-κB作为氧化应激导致心肌缺血再灌注损伤的通路蛋白参与其中。     

The role of neutrophils in myocardial ischemia-reperfusion injury

Reperfusion of ischemic myocardium is necessary to salvage tissue from eventual death. However, reperfusion after even brief periods of ischemia is associated with pathologic changes that represent either an acceleration of processes initiated during ischemia per se, or new pathophysiological changes that were initiated after reperfusion. This 'reperfusion injury' shares many characteristics with inflammatory responses in the myocardium. Neutrophils feature prominently in this inflammatory component of postischemic injury. Ischemia-reperfusion prompts a release of oxygen free radicals, cytokines and other proinflammatory mediators that activate both the neutrophils and the coronary vascular endothelium. Activation of these cell types promotes the expression of adhesion molecules on both the neutrophils and endothelium, which recruits neutrophils to the surface of the endothelium and initiate a specific cascade of cell-cell interactions, leading first to adherence of neutrophils to the vascular endothelium, followed later by transendothelial migration and direct interaction with myocytes. This specific series of events is a prerequisite to the phenotypic expression of reperfusion injury, including endothelial dysfunction, microvascular collapse and blood flow defects, myocardial infarction and apoptosis. Pharmacologic therapy can target the various components in this critical series of events. Effective targets for these pharmacologic agents include: (a) inhibiting the release or accumulation of proinflammatory mediators, (b) altering neutrophil or endothelial cell activation and (c) attenuating adhesion molecule expression on endothelium, neutrophils and myocytes. Monoclonal antibodies to adhesion molecules (P-selectin, L-selectin, CD11, CD18), complement fragments and receptors attenuate neutrophil-mediated injury (vascular injury, infarction), but clinical application may encounter limitations due to antigen-antibody reactions with the peptides. Humanized antibodies and non-peptide agents, such as oligosaccharide analogs to sialyl Lewis, may prove effective in this regard. Both nitric oxide and adenosine exhibit broad spectrum effects against neutrophil-mediated events and, therefore, can intervene at several critical points in the ischemic-reperfusion response, and may offer greater benefit than agents that interdict at a single point in the cascade. The understanding of the molecular processes regulating actions of neutrophils in ischemic-reperfusion injury may be applicable to other clinical situations, such as trauma, shock and organ or tissue (i.e. vascular conduits) transplantation.     

腺苷酸活化蛋白激酶与心肌缺血再灌注损伤

心肌缺血再灌注损伤（MIRI）是指缺血期处于可逆损伤的心肌细胞恢复血液供应后产生更为严重的损伤,主要包括炎症反应、内皮细胞损伤、血流障碍、心肌细胞坏死和凋亡所致心肌梗死面积的扩大、再灌注心律失常、心肌顿抑及冠状微循环障碍等病理生理变化.腺苷酸活化蛋白激酶（5-adenosine monophosphate activated kinase,AMPK）通过调节多种代谢途径控制着心脏能量的供求平衡.AMPK不仅控制葡萄糖和脂类的摄入、储存和利用,还能调节多种代谢酶的活性以及离子通道的开放和相关基因的表达[1].AMPK还能够调节缺血再灌注过程中心肌能量代谢,降低缺血性损伤和心肌凋亡.因此,AMPK被认为是能量应激下心肌细胞代谢调节的关键激酶.     

Effects of amlodipine on myocardial ischemia-reperfusion injury in dogs

The effects of the dihydropyridine calcium channel blocker amlodipine on subendocardial segment shortening (%SS), regional myocardial blood flow, myocardial high-energy phosphate levels and tissue water content were compared with those of a saline-treated group of barbital-anesthetized dogs subjected to a 45-minute coronary artery occlusion followed by 60 minutes of reperfusion. Saline or amlodipine (200 micrograms/kg administered intravenously) was given 15 minutes before coronary occlusion. There were no significant differences between groups in ischemic bed size or hemodynamics although dP/dt was higher after amlodipine administration. Subepicardial collateral blood flow was higher in the amlodipine group during coronary occlusion. After occlusion, %SS in the ischemic region was markedly decreased in both series and passive systolic lengthening resulted. Despite similar decreases in %SS during occlusion, the amlodipine-treated dogs showed a marked improvement in myocardial segment function of the ischemic reperfused region throughout 60 minutes of reperfusion compared with saline-treated dogs. In addition, amlodipine prevented the rebound increase in phosphocreatine and attenuated the loss of adenine nucleotides and increase in tissue water in the ischemic reperfused area at 60 minutes of reperfusion. These results suggest that amlodipine has a favorable effect on the functional and metabolic recovery of the ischemic reperfused myocardium and may have potential as a therapeutic agent for the treatment of coronary artery disease. The mechanism of action of amlodipine in this model is unknown but may be partially related to a drug-induced increase in coronary collateral blood flow or a decrease in afterload.     

柚皮素预处理对大鼠心肌缺血再灌注损伤的保护作用

目的观察柚皮素（naringenin,NAR）对大鼠心肌缺血再灌注损伤（IRI）的保护作用。方法32只雄性SD大鼠（220 g~250 g）随机分为假手术组（control,n=8）、IRI组（n=8）、NAR 50 mg/kg组（n=8）和NAR 100 mg/kg组（n=8）。NAR 50 mg/kg和NAR 100mg/kg组均在IRI前2 h予相应NAR腹腔注射。大鼠心肌IRI模型制备方法：结扎左冠状动脉前降支30 min,再灌注180 min,而后180 min检测各组大鼠血清白介素1β（IL-1β）、肿瘤坏死因子α（TNF-α）、乳酸脱氢酶（LDH）、肌酸激酶（CK）、超氧化物歧化酶（SOD）和丙二醛（MDA）含量以及再灌后24 h检测心肌梗死面积。结果NAR可显著降低大鼠心肌IRI后心肌梗死面积（与IRI相比,P＜0.05）,同时还可以显著减轻IRI后血清中IL-1β、TNF-α、LDH、CK和MDA的水平,增加SOD水平（与IRI相比,P＜0.05）,并呈浓度依赖性。结论NAR对心肌IRI具有明显的保护作用,其保护机制与抑制IRI后炎症反应和清除氧化应激损伤有关。     

Glutamine improves myocardial function following ischemia-reperfusion injury

Myocardial ischemia-reperfusion injury is common during cardiac procedures. Glutamine may protect the myocardium by preserving metabolic substrates. Glutamine (0.52 g x kg(-1)) or Ringer's lactate solution (control group) was administered intraperitoneally to 63 Sprague-Dawley rats at 4 or 18 hours prior to experimental ischemia and reperfusion. The hearts were excised and perfused on an isolated working heart model, exposed to global ischemia for 15 min and reperfusion for 1 hour. Left atrial pressure, mean aortic pressure, cardiac flow, coronary flow, and aortic output were measured 15 min before ischemia and every 15 min during reperfusion. There was significantly better cardiac output in the glutamine pretreated groups. Pretreatment at 4 hours before the experiment was superior to pretreatment at 18 hours, with better maintenance of cardiac output and coronary flow. The enhanced protective effect of pretreatment at 4 hours highlights the importance of timing, and suggests a potential clinical benefit.     

促红细胞生成素对大鼠心肌缺血再灌注损伤的影响

目的:观察促红细胞生成素(erythropoietin,EPO)对大鼠心肌缺血再灌损伤的影响,并探讨机制.方法:以左冠状动脉前降支(LAD)穿线结扎法制备心肌缺血模型,松开结扎线造成再灌注.45只SD大鼠随机分成5组:①假手术组,②缺血再灌注组,③磷脂酰肌醇-3-激酶(PI3K)的高选择性阻断剂LY294002组,④EPO 组和⑤EPO+LY294002组.观察心电图Ⅱ导联心律失常发生情况,进行室性心律失常评分;电镜观察心肌细胞超微结构;以TUNEL法检测细胞凋亡;检测血清肌酸磷酸激酶同工酶(CK-MB)和肌钙蛋白I(cTnI)水平.结果:EPO能降低心律失常评分(P<0.01),减轻心肌细胞超微结构损伤,减少细胞凋亡(P<0.01),降低血清CK-MB和cTnI水平(P<0.01),但这些作用可被预先给予的LY294002所减弱.结论:EPO能减轻心肌缺血再灌注损伤, PI3K参与其信号转导.     

The role of natural IgM in myocardial ischemia-reperfusion injury

Myocardial ischemia-reperfusion injury represents a combination of factors, namely the intrinsic cellular response to ischemia and the extrinsic acute inflammatory response. Recent studies in mesenteric and skeletal muscle reperfusion models identified natural IgM as a major initiator of pathology through the activation of the complement system and inflammatory cells. To determine whether a similar mechanism is involved in myocardial tissues, mice bearing an altered natural IgM repertoire (Cr2-/-) were examined in a murine model of coronary artery ischemia. Notably, these mice were significantly protected based on the reduced infarct size, limited apoptosis of cardiomyocytes, and decreased neutrophil infiltration. Protection was IgM-dependent as reconstitution of these mice with wild-type IgM restored myocardial reperfusion injury. These results support a model in which natural IgM initiates the acute inflammatory response in the myocardium following ischemia and reperfusion.     

褪黑激素对心肌缺血再灌注损伤的保护作用

目的 :探讨褪黑激素增补于停搏液中对缺血再灌注离体鼠心的保护作用。方法 :将 2 4只Wistar大鼠随机分为褪黑激素组 ,对照组。离体鼠心在改良的Langendorff Neely灌注模型上 30min预灌注 ,12 0min停搏 ,30min再灌注。缺血前及再灌注期间测定血流动力学指标 ,心肌酶 (CPK ,LDH)、心肌超氧化物歧化酶(SOD)、过氧化脂质 (LPO)含量。电镜观察心肌超微结构。结果 :再灌注后 ,褪黑激素组心功能、心肌超微结构的改善明显优于对照组 ;CPK ,LDH ,LPO含量显著低于对照组 (P <0 .0 1) ;SOD含量显著高于对照组 (P <0 .0 1)。结论 :褪黑激素增补于停搏液中可显著减轻心肌缺血再灌注损伤 ,具有良好的心肌保护作用     

细胞焦亡在心肌缺血再灌注损伤中的研究进展

心肌缺血再灌注损伤(MIRI)是导致心肌梗死患者经积极血运重建后仍发生较高死亡率的主要原因之一,寻找减轻MIRI的有效干预靶点并探索其保护机制具有重要的意义。细胞焦亡是细胞坏死和凋亡之外的一种炎性程序性细胞死亡方式。近年来,研究发现细胞焦亡与MIRI的发生发展具有密切联系。本文对细胞焦亡及其在MIRI中的作用机制进行综述,并讨论小分子药物、天然药物以及临床常用药物影响细胞焦亡并应用于MIRI防治的研究新进展。     

Metrnl与心肌缺血再灌注损伤的研究进展

镍纹样蛋白(Metrnl)作为一种新的脂肪因子,在人体内广泛分布.心肌缺血后的血运重建引起的心肌缺血再灌注损伤(MIRI)严重影响急性心肌梗死(AMI)患者的治疗预后,而Metrnl与MIRI的改善有着密切关系.该文就Metrnl与MIRI关系的研究进展作一综述.     

Mechanisms of flavonoid protection against myocardial ischemia-reperfusion injury

Flavonoids have long been acknowledged for their unique antioxidant properties, and possess other activities that may be relevant to heart ischemia-reperfusion. They may prevent production of oxidants (e.g. by inhibition of xanthine oxidase and chelation of transition metals), inhibit oxidants from attacking cellular targets (e.g. by electron donation and scavenging activities), block propagation of oxidative reactions (by chain-breaking antioxidant activity), and reinforce cellular antioxidant capacity (through sparing effects on other antioxidants and inducing expression of endogenous antioxidants). Flavonoids also possess anti-inflammatory and anti-platelet aggregation effects through inhibiting relevant enzymes and signaling pathways, resulting ultimately in lower oxidant production and better re-establishment of blood in the ischemic zone. Finally, flavonoids are vasodilatory through a variety of mechanisms, one of which is likely interaction with ion channels. These multifaceted activities of flavonoids raise their utility as possible therapeutic interventions to ameliorate ischemia-reperfusion injury.     

褪黑素对心肌缺血再灌注损伤的保护作用

目的　探讨褪黑素增补于停搏液中对缺血再灌注离体鼠心的保护作用。方法　将 2 4只 Wistar大鼠随机分为褪黑素组 (A )和对照组 (B)。离体鼠心在改良的 L angendorff- Neely灌注模型上 30分钟预灌注 ,12 0分钟停搏 ,30分钟再灌注。缺血前及再灌注期间测定血流动力学指标、心肌酶 (包括 CPK、L DH)、心肌超氧化物歧化酶 (SOD)、过氧化脂质 (L PO)含量。电镜观察心肌超微结构。结果　再灌注后 ,A组心功能、心肌超微结构的改善明显优于 B组 ;心肌酶 (CPK,L DH)、过氧化脂质 (L PO)含量显著低于 B组 (P<0 .0 1) ;心肌超氧化物歧化酶 (SOD)含量显著高于 B组 (P<0 .0 1)。结论　褪黑素增补于停搏液中可显著减轻心肌缺血再灌注损伤 ,具有良好的心肌保护作用     

三甲氧苄嗪对心肌缺血/再灌注损伤的保护作用

目的 :探讨三甲氧苄嗪增补于停搏液中对缺血 /再灌注离体鼠心的保护作用。方法 :将 2 4只 Wistar大鼠随机分为三甲氧苄嗪组 （A）和对照组 （B）。离体鼠心在改良的 L angendorff- Neely灌注模型上预灌注 30 min,停搏 12 0min、再灌注 30 min。缺血前及再灌注期间测定血流动力学指标、心肌酶 （CPK,L DH ）、心肌超氧化物歧化酶 （SOD）、过氧化脂质 （L PO）含量、心肌 ATP水平。电镜观察心肌超微结构。结果 :再灌注后 ,A组心功能、心肌超微结构的改善 ,明显优于 B组 ;心肌酶 （CPK ,L DH）、L PO含量显著低于 B组 （P<0 .0 1） ;SOD含量和 ATP水平显著高于 B组（P<0 .0 1）。结论 :三甲氧苄嗪增补于停搏液中可显著减轻心肌缺血 /再灌注损伤 ,具有良好的心肌保护作用     

LOX-1 abrogation reduces myocardial ischemia-reperfusion injury in mice

LOX-1 is a newly described lectin-like receptor for oxidized-LDL (ox-LDL), which is over-expressed in the ischemic myocardium. To examine the pathogenic role of LOX-1 in the determination of ischemia-reperfusion (I-R) injury to the heart, we developed LOX-1 knockout (KO) mice, and subjected these mice to 60 min of left coronary artery occlusion followed by 60 min of reperfusion. I-R in the LOX-1 KO mice resulted in a significant reduction in myocardial injury as well as in accumulation of inflammatory cells in the I-R myocardium and lipid peroxidation (P < 0.01 vs. wild-type mice). Concomitantly, there was significant preservation of cardiac function in the LOX-1 KO mice despite I-R (P < 0.01 vs. the wild-type mice). The phosphorylation of oxidative stress-sensitive mitogen-activated protein kinase (p38MAPK) and protein kinase B/Akt-1, expression of nitrotyrosine and inducible nitric oxide synthase (iNOS), and superoxide dismutase activity were enhanced during I-R in the wild-type mice. These alterations in p38MAPK, Akt-1 and iNOS were much less pronounced in the LOX-1 KO mice. The superoxide dismutase activity increased further in the LOX-1 KO mice. These observations provide compelling evidence that LOX-1 may be a key modulator of myocardial I-R injury, and its effect is mediated by pro-oxidant signals. LOX-1 may be a potential target for therapy of myocardial ischemic injury.     

法舒地尔对大鼠离体心脏缺血/再灌注损伤的保护作用

目的观察盐酸法舒地尔对大鼠离体心脏缺血/再灌注（I/R）损伤是否有保护作用。方法SD大鼠19只,随机分为3组:I/R组、I/R+F组和对照组。用改良的Langendorff灌流装置,用K-H液行主动脉逆行灌流,建立大鼠离体心脏I/R损伤实验模型。I/R组预灌流20 min,停灌45 min,再灌30 min;I/R+F组于再灌注时在灌流液中加入盐酸法舒地尔注射液（10 mg/kg）;对照组连续灌流95 min。连续记录左心室收缩功能曲线,收集冠脉流出液,检测冠脉流出液中乳酸脱氢酶（LDH）、肌酸激酶（CK）、肌红蛋白（Mb）漏出量以及心肌细胞内钙、心肌组织一氧化氮（NO）含量和髓过氧化物酶（MPO）活力。结果心肌缺血使冠脉流出量减少,LDH、CK、Mb增加,再灌注后冠脉流出量进一步减少,LDH、CK、Mb进一步增加,同时增加细胞内钙,增加MPO活力,减少NO生成。盐酸法舒地尔逆转再灌注后冠脉流出量减少和LDH、CK和Mb漏出增加,降低细胞内钙、MPO活力,逆转NO生成减少。I/R使左室发展峰压平均值、平均±dp/dtmax均下降,盐酸法舒地尔对左室发展峰压的改变无明显影响,但改善±dp/dtmax降低。结论盐酸法舒地尔对心肌I/R损伤有保护作用,增强I/R引起的"无复流"现象和心肌收缩能力降低的恢复,此作用与逆转NO生成减少、MPO活性增高和细胞内钙超载等因素有关。