心肌缺血后处理胞内信号转导研究进展

缺血后处理对心肌再灌注损伤的保护是多因素参与的复杂过程。后处理对心肌的保护除了通过减少活性氧类物质的产生、抑制线粒体内钙超载、减轻内皮功能失调等被动作用外,还可主动激活再灌注损伤补救激酶（reperfusion injury salvage kinase,RISK）途径及其他蛋白激酶而实现。本文将对心肌缺血后处理中RISK通路的研究进展作一综述。     

Cariporide和还原型谷胱甘肽药物后适应对心肌缺血／再灌注损伤的保护作用

目的：观察钠氢交换阻断剂cariporide和抗氧化剂还原型谷胱甘肽（GSH）建立的药物后适应对心肌缺血／再灌注损伤的保护效应。方法：建立在体大鼠心肌缺血／再灌注模型,观察不同实验组间心梗面积和心肌酶学变化。结果：caripofide和GSH药物后适应可以减小心肌梗死面积,降低血浆磷酸肌酸激酶（CK）及丙二醛（MDA）的含量。结论：在心肌再灌注的开始,一次性给予钠氢交换阻断剂cariporide或抗氧化剂GSH,可减轻缺血／再灌注损伤,是两种有效的药物后适应干预。     

腺苷预处理对培养大鼠心肌细胞"缺血-再灌注"性膜损伤的影响

目的探讨腺苷预处理对缺血-再灌注心肌细胞膜损伤的保护作用.方法将培养5天的SD乳鼠心肌细胞随机分成4组正常组常规条件下(DMEM培养基及95% 空气+ 5% CO2 气体环境)培养50min;拟缺血/再灌注组先在缺糖缺氧条件下(无糖Eagle 培养基及95% N2+ 5% CO2 气体环境)培养30min,再恢复常规条件培养20min;拟缺血预处理组先缺糖缺氧培养5min,再复氧复糖培养5min,反复3次后按模拟缺血/再灌注组操作;腺苷预处理组用含腺苷(0.15g/L)培养液在常规条件下培养10min,再作拟缺血/再灌注组处理.扫描电镜下观察各组细胞的变化,并用胶体苯胺染色及Ridit分析法对PLA活性进行半定量.结果与正常组比较,模拟缺血/再灌注组细胞的质膜和线粒体的结构损伤严重,PLA活性显著性增强.而模拟缺血预处理和腺苷预处理组细胞质膜和线粒体损伤较轻,PLA活性显著低于拟缺血/再灌注组.结论腺苷预处理对"缺血-再灌注"损伤心肌的细胞膜有保护作用,其机制可能与腺苷直接或间接地抑制PLA活性,增强质膜的稳定性有关.     

心肌再灌注损伤保护的机制和策略

局部缺血部位快速再灌注虽然保护了心肌,但也引起再灌注损伤。目前还没有减轻再灌注损伤的特效疗法,但近年来研究显示,G蛋白耦联受体（Gprotein-coupledreceptor,GPCR）的激动剂、胰岛素和缺血后处理可以在各种实验条件和各类动物模型中有效抵抗再灌注损伤。这些干预手段启动的心脏保护机制可能包括激活再灌注损伤补救激酶（reperfus ioninjury salvage kinase,RISK）途径、抑制糖原合酶激酶-3β（glycogen synthase kinase3β,GSK-3β）以及抑制线粒体膜通透性转换孔（mitochondrial permeabili tytransition pore,mPTP）开放等。这些研究成果有利于开发治疗急性心肌梗死的有效临床手段。     

中药抗心肌缺血再灌注损伤的信号通路研究进展

冠心病发生率、致死率高,严重危害人类健康。心肌缺血再灌注损伤是加重心肌损伤的主要病理机制,干预再灌注损伤挽救激酶、 单磷酸腺苷激酶、蛋白激酶 C 等信号传导通路保护心肌,成为减轻心肌损伤的重要途径之一。综述近 3 年国际期刊收录的中药有效成分、 提取物及复方制剂调节相关信号传导通路, 减轻心肌再灌注损伤的研究进展, 以期为阐释中药的作用特点, 有效防治心血管疾病提供参考。     

大鼠肢体预缺血减小心肌缺血-再灌注后的梗塞范围

在氨基甲酸乙酯麻醉大鼠上观察肢体预缺血(limb ischemic preconditioning,LIP)对缺血-再灌注(ischemia—reperfusion,IR)心肌的影响,旨在探讨LIP对IR心肌有无保护效应,并明确腺苷和神经通路是否参与此效应。所得结果如下:(1)在心脏缺血30 min和再灌注120 min过程中,梗塞心肌占缺血心肌的51.48±0.82％。(2)LIP时心肌梗塞范围为35.14±0.88％,较单纯心肌缺血-再灌注时显著减小(P<0.01),表明LIP对心肌有保护作用。(3)事先切断股神经可取消LIP的保护效应。(4)股动脉内局部给予腺苷(10nmol/kg),可模拟LIP对心肌的保护作用;心肌梗塞范围是37.28±1.68％,而股静脉内注射同等剂量腺苷则无保护作用。(5)股动脉内预先应用腺苷A.受体拈抗剂8-环戊-1,3-二丙基嘌呤(DPCPX)(32 nmol/kg)可部分阻断LIP诱发的心肌保护效应。以上结果表明,肢体短暂预缺血可减小心肌缺血-再灌注后的梗塞范围,而局部释放的腺苷和由此所激活的相关的神经通路在LIP的心肌保护中起重要作用。     

青霉胺对缺血后再灌注心肌损伤的保护作用

为了解青霉胺对缺血后再灌注心肌损伤的影响,我们采用Ｌａｎｇｅｎｄｒｏｆ离体大鼠心脏灌注模型,先灌注１５ｍｉｎ后停止灌注,模拟缺血６０ｍｉｎ,然后再灌注６０ｍｉｎ。动物分为对照组及青霉胺处理组（３０ｍＭ）。分别测定缺血前及再灌注后心肌组织内三磷酸腺苷（ＡＴＰ）、谷胱甘肽（ＧＳＨ）及谷胱甘肽氧化酶（ＧＳＨ－Ｐｘ）的含量变化,再灌注过程中冠状动脉血流阻力及冠脉流出液中磷酸肌酸激酶（ＣＰＫ）的释放量。结果显示,青霉胺处理组再灌注后心肌组织的ＡＴＰ、ＧＳＨ、ＧＳＨ－Ｐｘ含量均明显高于对照心肌组织中的含量,而青霉胺处理组在再灌注过程中ＣＰＫ的总释放量及平均冠状血流动脉阻力明显低于对照组ＣＰＫ总释放量及平均冠状动脉血流阻力。提示青霉胺可以减轻缺血后再灌注的心肌的损伤,起到保护作用     

缺血后处理内源性心脏保护的研究进展

再灌注疗法是临床治疗心肌缺血最有效的措施,但会引起再灌注损伤,调动机体内源性保护机制可以减轻再灌注损伤,保护缺血心肌。缺血预处理（ischemic preconditioning,IPC）和后处理（ischemic postconditioning,I-postC）是缺血心脏有效的内源性保护现象,可以减轻缺血再灌注（ischemia／reperfusion,I／R）后心肌坏死与心肌功能障碍,减少恶性心律失常的发生。内源性心脏保护的机制主要是通过诱导触发因子释放,经多条细胞内信号转导途径的介导,作用于多种效应器,影响氧自由基产生、钙超载等I／R损伤的关键环节而发挥心肌细胞保护作用。特别是可以在缺血后实施的I-postC具有良好的临床应用前景。本文以I-postC为重点综述内源性心脏保护作用、机制及其临床应用现状。     

后适应缺血时间窗的选择对小鼠心肌再灌注损伤的影响

目的 探讨后适应对小鼠心肌再灌注损伤的影响以及不同缺血时间窗的后适应心脏保护作用的差异 .方法 96只成年C57/BL小鼠随机分为缺血时间30、45 min和60 min的三组,每组又分为后适应和缺血再灌注两种处理.通过开胸结扎左冠状动脉造成急性心肌梗死 ,在完全再灌注早期给予反复短暂再通/闭塞的缺血后适应.采用Evans blue和TTC染色的方法确定缺血心肌和梗死心肌面积,并测定血清的心肌酶含量、心肌超氧化物歧化酶 (SOD) 活性与丙二醛 (MDA) 水平以及血流动力学指标.结果 缺血30 min后适应组、缺血45 min后适应组心肌梗死面积分别比相同缺血时间的再灌注对照组减少53.1%和31.2%,差异均具有统计学意义(P<0.01),缺血后适应可明显降低血清心肌酶、提高心肌SOD的活性以及改善血流动力学的恶化;缺血60 min后适应组梗死心肌面积无明显降低, 差异无统计学意义(P＞0.05).结论 小鼠心肌处于轻中度水平的缺血损伤,在恢复冠脉血流的早期施行缺血后适应可以有效地减少心肌再灌注损伤,但随着缺血时间的延长,心肌保护作用就明显减弱或消失.     

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。     

Endoplasmic reticulum stress-induced hepatic stellate cell apoptosis through calcium-mediated JNK/P38 MAPK and Calpain/Caspase-12 pathways

Since ischemic heart disease (IHD) is a major cause of mortality and heart failure, novel therapeutic strategies are expected to improve the clinical outcomes of patients with acute myocardial infarction. Brief episodes of ischemia/reperfusion performed at the onset of reperfusion can reduce infarct size; a phenomenon termed “ischemic postconditioning.” Extensive research has determined that different autacoids (e.g., adenosine, bradykinin, opioid, etc.) and cytokines, their respective receptors, kinase signaling pathways, and mitochondrial modulation are involved in ischemic conditioning. Modification of these factors by pharmacological agents mimics the cardioprotection by ischemic postconditioning. Here, the potential mechanisms of ischemic postconditioning, the presence of comorbidities, and the possible extrapolation to the clinical setting are reviewed. In the near future, large, multicentered, randomized, placebo-controlled, clinical trials will be required to determine whether pharmacological and/or ischemic postconditioning can improve the clinical outcomes of patients with IHD.     

Pharmacological postconditioning by bolus injection of phosphodiesterase-5 inhibitors vardenafil and sildenafil

Postconditioning enables cardioprotection against ischemia/reperfusion injury either by application of short, repetitive ischemic periods or by pharmacological intervention prior to reperfusion. Pharmacological postconditioning has been described for phosphodiesterase-5 inhibitors when the substances were applied as a permanent infusion. For clinical purposes, application of a bolus is more convenient. In a rat heart in situ model of ischemia reperfusion vardenafil or sildenafil were applied as a bolus prior to reperfusion. Cardioprotective effects were found over a broad dosage range. In accordance with current hypotheses on pharmacological postconditioning signaling, the protective effect was mediated by extracellular signal-regulated kinase and protein kinase C pathway. Interestingly, the extent of protection was independent of the concentration applied for both substances. Full protection comparable to ischemic postconditioning was reached with half-maximal human equivalence dose. In contrast, mean arterial pressure dropped upon bolus application in a dose-dependent manner. Taken together, the current study extends previous findings obtained in a permanent infusion model to bolus application. This is an important step toward clinical application of pharmacological postconditioning with sildenafil and vardenafil, especially because the beneficial effects were proven for concentrations with reduced hemodynamic side effects compared to the dosage applied for erectile dysfunction treatment.     

Attenuation of ischemia–reperfusion injury by sevoflurane postconditioning involves protein kinase B and glycogen synthase kinase 3 beta activation in isolated rat hearts

Volatile anesthetic ischemic postconditioning reduces infarct size following ischemia/reperfusion. Whether phosphorylation of protein kinase B (PKB/Akt) and glycogen synthase kinase 3 beta (GSK3β) is causal for cardioprotection by postconditioning is controversial. We therefore investigated the impact of PKB/Akt and GSK3β in isolated perfused rat hearts subjected to 40 min of ischemia followed by 1 h of reperfusion. 2.0% sevoflurane (1.0 minimum alveolar concentration) was administered at the onset of reperfusion in 15 min as postconditioning. Western blot analysis was used to determine phosphorylation of PKB/Akt and its downstream target GSK3β after 1 h of reperfusion. Mitochondrial and cytosolic content of cytochrome C checked by western blot served as a marker for mitochondrial permeability transition pore opening. Sevoflurane postconditioning significantly improved functional cardiac recovery and decreased infarct size in isolated rat hearts. Compared with unprotected hearts, sevoflurane postconditioning-induced phosphorylation of PKB/Akt and GSK3β were significantly increased. Increase of cytochrome C in mitochondria and decrease of it in cytosol is significant when compared with unprotected ones which have reversal effects on cytochrome C. The current study presents evidence that sevoflurane-induced cardioprotection at the onset of reperfusion are partly through activation of PKB/Akt and GSK3β.     

Hypercholesterolemic Myocardium Is Vulnerable to Ischemia-Reperfusion Injury and Refractory to Sevoflurane-Induced Protection

Recent studies have demonstrated that volatile anesthetic postconditioning confers myocardial protection against ischemia-reperfusion (IR) injury through activation of the reperfusion injury salvage kinase (RISK) pathway. As RISK has been shown to be impaired in hypercholesterolemia. Therefore, we investigate whether anesthetic-induced cardiac protection was maintained in hypercholesterolemic rats. In the present study, normocholesteolemic or hypercholesterolemic rat hearts were subjected to 30 min of ischemia and 2 h of reperfusion. Animals received 2.4% sevoflurane for 5 min or 3 cycles of 10-s ischemia/10-s reperfusion. The hemodynamic parameters, including left ventricular developed pressure, left ventricular end-diastolic pressure and heart rate, were continuously monitored. The infarct size, apoptosis, p-Akt, p-ERK1/2, p-GSK3β were determined. We found that both sevoflurane and ischemic postconditioning significantly improved heart pump function, reduced infarct size and increased the phosphorylation of Akt, ERK1/2 and their downstream target of GSK3β in the healthy rats. In the hypercholesterolemic rats, neither sevoflurane nor ischemic postconditioning improved left ventricular hemodynamics, reduced infarct size and increased the phosphorylated Akt, ERK1/2 and GSK3β. In contrast, GSK inhibitor SB216763 conferred cardioprotection against IR injury in healthy and hypercholesterolemic hearts. In conclusions, hyperchoesterolemia abrogated sevoflurane-induced cardioprotection against IR injury by alteration of upstream signaling of GSK3β and acute GSK inhibition may provide a novel therapeutic strategy to protect hypercholesterolemic hearts against IR injury.     

Sphingosine kinase and sphingosine 1-phosphate in the heart: A decade of progress

Activation of sphingosine kinase/sphingosine 1-phosphate (SK/S1P)‐mediated signaling has emerged as a critical cardioprotective pathway in response to acute ischemia/reperfusion injury. S1P is released in both ischemic pre- and post-conditioning. Application of exogenous S1P to cultured cardiac myocytes subjected to hypoxia or treatment of isolated hearts either before ischemia or at the onset of reperfusion exerts prosurvival effects. Synthetic congeners of S1P such as FTY720 mimic these responses. Gene targeted mice null for the SK1 isoform whose hearts are subjected to ischemia/reperfusion injury exhibit increased infarct size and respond poorly either to ischemic pre- or postconditioning. Measurements of cardiac SK activity and S1P parallel these observations. Experiments in SK2 knockout mice have revealed that this isoform is necessary for survival in the heart. High density lipoprotein (HDL) is a major carrier of S1P, and studies of hearts in which selected S1P receptors have been inhibited implicate the S1P cargo of HDL in cardioprotection. Inhibition of S1P lyase, an endogenous enzyme that degrades S1P, also leads to cardioprotection. These observations have considerable relevance for future therapeutic approaches to acute and chronic myocardial injury. This article is part of a Special Issue entitled Advances in Lysophospholipid Research.     

Pathophysiology of myocardial reperfusion injury: preconditioning, postconditioning, and translational aspects of protective measures

Heart diseases due to myocardial ischemia, such as myocardial infarction or ischemic heart failure, are major causes of death in developed countries, and their number is unfortunately still growing. Preliminary exploration into the pathophysiology of ischemia-reperfusion injury, together with the accumulation of clinical evidence, led to the discovery of ischemic preconditioning, which has been the main hypothesis for over three decades for how ischemia-reperfusion injury can be attenuated. The subcellular pathophysiological mechanism of ischemia-reperfusion injury and preconditioning-induced cardioprotection is not well understood, but extensive research into components, including autacoids, ion channels, receptors, subcellular signaling cascades, and mitochondrial modulators, as well as strategies for modulating these components, has made evolutional progress. Owing to the accumulation of both basic and clinical evidence, the idea of ischemic postconditioning with a cardioprotective potential has been discovered and established, making it possible to apply this knowledge in the clinical setting after ischemia-reperfusion insult. Another a great outcome has been the launch of translational studies that apply basic findings for manipulating ischemia-reperfusion injury into practical clinical treatments against ischemic heart diseases. In this review, we discuss the current findings regarding the fundamental pathophysiological mechanisms of ischemia-reperfusion injury, the associated protective mechanisms of ischemic pre- and postconditioning, and the potential seeds for molecular, pharmacological, or mechanical treatments against ischemia-reperfusion injury, as well as subsequent adverse outcomes by modulation of subcellular signaling mechanisms (especially mitochondrial function). We also review emerging translational clinical trials and the subsistent clinical comorbidities that need to be overcome to make these trials applicable in clinical medicine.     

Postconditioning reduces infarct size and cardiac myocyte apoptosis via the opioid receptor and JAK-STAT signaling pathway

Brief intermittent episodes of ischemia and reperfusion could reduce infarct size, a phenomenon called ??postconditioning?? at the onset of reperfusion after a prolonged period of ischemia. To investigate whether the opioid receptors and signaling factor JAK-STAT might be responsible for the cardioprotection in ischemic postconditioning, and the possible molecular machinery of cardioprotection. Hundred and twenty healthy New Zealand rabbits were divided into six groups. The myocardial infarct size, cardiac myocyte apoptosis, BCL-2 and P-Stat3 protein expression were tested in the current study. The results suggested that ischemic postconditioning might increase BCL-2 protein expression by activating the opioid receptors and JAK-STAT signaling pathway, and also to reduce ischemia-reperfusion-induced cardiomyocyte apoptosis and to play a key role in myocardial protection. However, further research still needs to be done to unravel the underlying mechanisms.     

Hydrogen sulfide post-conditioning preserves interfibrillar mitochondria of rat heart during ischemia reperfusion injury

Cardiac mitochondrial dysfunction is considered to be the main manifestation in the pathology of ischemia reperfusion injury, and by restoring its functional activity, hydrogen sulfide (H₂S), a novel endogenous gaseotransmitter renders cardioprotection. Given that interfibrillar (IFM) and subsarcolemmal (SSM) mitochondria are the two main types in the heart, the present study investigates the specific H₂S-mediated action on IFM and SSM during ischemic reperfusion in the Langendorff rat heart model. Rats were randomly divided into five groups, namely normal, ischemic control, reperfusion control (I/R), ischemic post-conditioning (POC), and H₂S post-conditioning (POC_H₂S). In reperfusion control, cardiac contractility decreased, and lactate dehydrogenase, creatine kinase, and infracted size increased compared to both normal and ischemic group. In hearts post-conditioned with H₂S and the classical method improved cardiac mechanical function and decreased cardiac markers in the perfusate and infarct size significantly. Both POC and POC_H₂S exerts its cardioprotective effect of preserving the IFM, as evident by significant improvement in electron transport chain enzyme activities and mitochondrial respiration. The in vitro action of H₂S on IFM and SSM from normal and I/R rat heart supports H₂S and mediates cardioprotection via IFM preservation. Our study indicates that IFM play an important role in POC_H₂S mediated cardioprotection from reperfusion injury.