临床应用心肌缺血预适应与后适应的哲学理论

及时恢复缺血区的血液灌注即再灌注是临床上挽救缺血心肌的最有效措施,但再灌注会引起严重的再灌注损伤。心肌缺血预适应和后适应可以减轻缺血再灌注损伤后心肌的坏死与心肌功能障碍,减少恶性心律失常的发生,是减轻缺血再灌注损伤的有效内源性保护手段。心肌缺血预适应和后适应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,影响缺血再灌注损伤的关键环节而发挥心肌细胞保护作用。心肌缺血预适应和后适应是内因和外因的辩证统一,也蕴含矛盾双方互相转化的规律。     

缺血后适应干预缺血再灌注心肌相关信号通路的研究进展

<正> 再灌注治疗可挽救急性心肌梗死(acute myocardial infarction,AMI)濒临死亡的心肌,但随后的缺血冉灌注(ischemicreperfusion,I/R)损伤却减弱了冉灌注治疗带来的益处。作为再灌注治疗的一种辅助方法,缺血预适应可以缩小心肌梗死范围,然而必须在缺血事件发生前应用才能发挥保护心     

缺血后适应对缺血/再灌注损伤的心肌保护

急性心肌梗死的再灌注治疗一方面恢复了心肌的血供,另一方面也可能加重缺血心肌的损伤（再灌注损伤）。近年来研究发现,在冠状动脉再灌注开始时对冠脉进行短暂、重复的开通及再闭过程,随后恢复冠状动脉血流,即"缺血后适应",能减少缺血心肌的再灌注损伤,缩小缺血心肌的梗死面积。本文就其研究现状综述如下。     

腺苷后适应对心肌缺血再灌注损伤的保护作用及机制研究

目的 初步探讨腺苷后适应(ADOP)对缺血再灌注损伤(MRI)心肌的保护作用及机制.方法 48只健康雄性SD大鼠随机分为4组:假手术组、缺血再灌注组、缺血后处理组及腺苷后适应组,每组12只,建立大鼠心肌缺血再灌注模型.实验终点测定心肌梗死面积(TTC染色),RT-PCR检测心肌核因子-kB(NF-kB)mRNA的表达水平,同时观察心肌组织中白细胞介素-6(IL-6)、丙二醛(MDA)及超氧化物歧化酶(SOD)的含量变化,并行心肌组织病理学检查.结果 与缺血再灌注组比较,ADOP组的心肌梗死面积、NF-kB mRNA的表达水平及IL-69、MDA含量明显降低(P<0.01),而SOD含量则显著升高(P<0.01),同时心肌组织病理学损伤亦明显减轻;而ADOP组与缺血后处理组相比,除NF-kB ,RNA的表达及IL-6的分泌显著降低(P<0.05)外,其他指标均无显著差异.结论 ADOP可通过抑制再灌注后氧自由基的过量生成及NF-KB活化所诱导的早期炎症反应,增强心肌抗氧化能力,改善心肌微循环,并发挥保护效应.     

缺血后适应对大鼠心肌缺血再灌注后血流动力学改善的影响

目的 研究缺血后适应(ischemic postconditioning,IPO)对正常离体大鼠心肌再灌注后血流动力学的改善作用.方法 采用正常离体大鼠心脏Langendorff灌流方法,全心停灌30 min,复灌60 min复制成心肌缺血的再灌注损伤(I/R)模型,测定血流动力学指标和再灌30 min冠脉流出液中乳酸脱氢酶(LDH)、肌酸激酶(CK)含量.实验结束后分离出左心室心肌并横切成5片,置入TTC中测定心梗面积.结果 离体大鼠心肌缺血后适应干预后可显著改善再灌注后左室收缩压(LVSP)以及左心室内压最大上升速率(+dP/dtmax)等血流变学指标,并显著减少了再灌注后LDH与CK的释放量及室性心律失常的发生;同时后适应干预减少了心肌梗死面积(47.3%,29.5%).结论 缺血后适应处理对离体大鼠缺血再灌注后的血流动力学指标损伤有明确的改善作用,预防了心肌缺血再灌注损伤.     

缺血后适应对兔心肌细胞凋亡的影响

目的 探讨缺血后适应对兔心肌梗死面积及细胞凋亡的影响.方法 32只成年新西兰雄性大白兔接受缺血30 min再灌注3 h,随机分为缺血再灌注组、缺血后适应组、缺血后适应+wortmannin(PI3K阻滞剂)组、缺血再灌注+wortmannin组.采用Evans蓝和TTC染色的方法确定缺血心肌面积以及梗死心肌面积,采用TUNEL法检测凋亡心肌细胞.结果 与缺血再灌注组比较,缺血后适应组梗死心肌面积百分比及凋亡心肌细胞百分比显著减低(均P<0.05).而在后适应+wortmannin 组无明显减低(P>0.05).结论 缺血后适应可以有效地减少缺血再灌注兔心肌梗死面积细胞凋亡百分比,wortmannin抑制了后适应的作用,提示PI3K的活化在缺血后适应中具有重要作用.     

心肌缺血后适应的保护作用及机制研究进展

急性心肌梗死发病率的增高,促进了再灌注治疗如溶栓及经皮冠脉介入治疗的应用.这却引起了心肌细胞死亡、血流动力学障碍、再灌注心律失常及内皮功能障碍等缺血再灌注损伤[1].众多研究证实,缺血后适应对缺血再灌注损伤心肌具有保护作用,能够降低梗死面积[2]、减少细胞凋亡[3]、改善内皮功能[4]及减轻组织的水肿[4]等.缺血后适应,即在心肌缺血再灌注的即刻对冠脉进行短暂、重复的开通及再闭过程,随后恢复冠状动脉血流[4].后适应的可操作性,决定了其在临床中应用的可能性.本文就后适应在心肌缺血再灌注损伤中的保护应用及其机制进行综述.     

PTEN在心肌缺血预适应和后适应中的调控作用

目的探讨人第10号染色体缺失的磷酸酶及张力蛋白同源的基因(PTEN)/Akt信号通路在心肌缺血预适应和后适应中的作用。方法雄性SD大鼠60只,随机分为4组:假手术组(sham组)、缺血再灌注组(IR组)、缺血预适应组(Ipre组)及缺血后适应组(Ipost组)。建立动物模型,实验结束后,计算心肌梗死面积,测定血清肌酸激酶(CK)、乳酸脱氢酶(LDH)活性,检测缺血心肌PTEN m RNA和蛋白含量及p-Akt蛋白表达水平。结果与IR组比较,Ipre组和Ipost组的心肌梗死面积明显缩小,CK、LDH的活性降低,PTEN m RNA和蛋白的含量降低,p-Akt蛋白的水平升高(P0.05)。结论 PTEN/Akt信号通路在心肌缺血再灌注损伤中发挥重要作用,心肌缺血预适应和后适应通过调节PTEN/Akt信号通路的表达在缺血再灌注损伤中发挥保护心肌的作用。     

心肌缺血再灌注损伤与后适应

及时再灌注治疗,如溶栓、经皮冠状动脉介入治疗（PCI）等可以重建冠状动脉血运,使心肌得到再灌注,从而减少心肌坏死面积,是急性心肌梗死（AMI）治疗的关键。但近来研究发现,冠状动脉的骤然开通与血流恢复,会引起血管内皮细胞功能异常、激活炎症因子等,反而加重缺血心肌的损伤,导致再灌注损伤.AMI的动物研究结果表明,40%～50%的坏死心肌为再灌注损伤引起,这种损伤的存在减弱了积极再灌注治疗所得到的益处,因此,减少再灌注损伤成为AMI防治的重要环节。     

远距缺血后适应对缺血再灌注心肌的保护作用

目的:探讨远距缺血后适应(RIP)对兔局部短期缺血再灌注心肌的保护作用.方法:将24只新西兰白兔随机平均分成4组:假手术对照组(S组)、缺血再灌注对照组(IR组)、缺血后适应组(Post组)、RIP组.采用TUNEL分析检测各组心肌组织的细胞凋亡情况,Western blot方法检测Bcl-2、Bax蛋白的表达.结果:...     

Remote postconditioning

Objectives A series of brief coronary artery reperfusions and reocclusions applied during the early minutes of coronary artery reflow (“postconditioning”) attenuates reperfusion injury. However, it is not known whether brief ischemia–reperfusion applied to a distant organ at the onset of myocardial reperfusion (i.e. “remote postconditioning”, remote PostC) reduces infarct size in the reperfused myocardium. In an in vivo anesthetized rat model of myocardial infarction induced by coronary artery occlusion and reperfusion, this study tested the hypothesis that remote postC induced by a single 5 minute episode of renal artery (RA) occlusion and reperfusion applied immediately before the onset of coronary artery reperfusion protects the myocardium from reperfusion injury by mechanisms involving endogenous adenosine receptor activation. Methods All rats were subjected to a total of 30 minutes of left coronary artery occlusion (LCAO) and 3 hours of reperfusion. The rats were randomized to one of six groups: 1) Control: LCAO and reperfusion only with no other intervention; 2) Remote PostC: after 24 minutes of LCAO the RA was occluded for 5 minutes and released 1 min before coronary artery reperfusion; 3) Permanent RA occlusion: the RA was permanently occluded after 24 minutes LCAO continuing to the end of reperfusion; 4) Delayed Remote PostC: after 26 minutes LCAO the RA was occluded for 5 minutes, and its release was delayed until 1 min after coronary artery reperfusion; 5) CON + SPT: rats with LCAO and reperfusion received 10 mg/kg IV of the non–selective adenosine receptor antagonist 8–sulfophenyl theophylline [SPT] administered 5 minutes before coronary artery reperfusion; and 6) Remote PostC + SPT: after 24 minutes of LCAO the RA was occluded for 5 minutes and released 1 minute before coronary artery reperfusion in the presence of 10 mg/kg SPT given 5 min before coronary artery reperfusion. Results Myocardial infarct size (percentage necrosis/area at risk, mean ± SEM) was reduced by 50% in Remote PostC (25 ± 4%) compared to Control (49 ± 4%, p = 0.003), consistent with a reduction in plasma CK activity (44 ± 5 vs. 67 ± 6 U/ml, p = 0.023). In contrast, permanent RA occlusion before LCAO and reperfusion failed to reduce myocardial infarct size (47 ± 5%) vs Control. Delaying the release of the RA occlusion (delayed Remote PostC) abrogated the myocardial infarct reduction observed with Remote PostC (48 ± 6%). SPT alone had no effect on infarct size (47 ± 4% in CON + SPT vs. 49 ± 4% in CON); however, Remote PostC+SPT abrogated the myocardial infarct size reduction in Remote PostC (50 ± 3% in Remote PostC + SPT vs. 25 ± 4% in Remote PostC). Conclusions Remote renal postconditioning applied immediately before the onset of coronary artery reperfusion provides potent myocardial infarct size reduction likely exerted during the first minutes of coronary artery reperfusion. This inter–organ remote postconditioning phenomenon is likely mediated in part by release of adenosine by the ischemic–reperfused kidney and subsequent activation of adenosine receptors.     

远隔缺血后适应

远隔缺血后适应(remote ischemic postconditioning,RIP)是指重要器官长时程致死性缺血损伤后,对非生命重要器官进行的短暂的非致死性缺血适应.相对于远隔缺血预适应,RIP更具有临床应用价值.然而,RIP尚处于研究认识阶段.文章对各个系统的RIP研究进展进行了综述.     

远隔缺血后适应

远隔缺血后适应(remote ischemic postconditioning,RIP)是指重要器官长时程致死性缺血损伤后,对非生命重要器官进行的短暂的非致死性缺血适应.相对于远隔缺血预适应,RIP更具有临床应用价值.然而,RIP尚处于研究认识阶段.文章对各个系统的RIP研究进展进行了综述.     

远隔缺血后适应

远隔缺血后适应(remote ischemic postconditioning,RIP)是指重要器官长时程致死性缺血损伤后,对非生命重要器官进行的短暂的非致死性缺血适应.相对于远隔缺血预适应,RIP更具有临床应用价值.然而,RIP尚处于研究认识阶段.文章对各个系统的RIP研究进展进行了综述.     

缺血后处理和三磷酸腺苷后处理对心肌缺血再灌注损伤的影响

目的观察缺血后处理(IPO)、ATP和腺苷受体激动剂CGS-21680后处理对心肌缺血再灌注损伤的影响。方法健康新西兰大白兔48只,随机分为对照组、IPO组、ATP组、CGS-21680组,每组12只。测定肌酸激酶同工酶(CK-MB)、丙二醛水平及超氧化物歧化酶(SOD)活力;计算各组兔心肌梗死面积;HE染色观察心肌组织病理形态变化;TUNEL法检测心肌细胞凋亡;实时荧光定量RT-PCR检测心肌组织天冬氨酸特异性半胱氨酸蛋白酶3(caspase-3)mR NA和Bcl-2 mRNA的表达。结果与对照组比较,IPO组、ATP组和CGS21680组血清丙二醛、CK-MB水平及心肌梗死面积明显降低,SOD活力明显升高。IPO组、ATP组和CGS-21680组心肌细胞凋亡指数较对照组明显降低,心肌组织损伤明显减轻。IPO组、ATP组和CGS-21680组较对照组caspase-3 mRNA表达明显下调,Bcl-2 mRNA表达明显上调。结论 IPO与ATP后处理可通过激活腺苷A2a受体,减轻心肌缺血再灌注损伤,其机制可能与上调Bcl-2和下调caspase-3的表达,抑制氧自由基氧化应激损伤,减少细胞凋亡有关。     

缺血后处理的神经保护机制

脑缺血后处理是指在脑缺血后再灌注早期实施的一系列间断性血流阻断,以减轻缺血再灌注损伤.由于其具有很好的临床应用前景,近年来受到广泛关注.文章对缺血后处理的神经保护机制做一综述.     

Mitochondrial permeability transition pore and postconditioning

Postconditioning has recently been described as a powerful cardioprotection that prevents lethal reperfusion injury. Growing evidence suggests that mitochondrial permeability transition may be a key event in postconditioning. This proposition arises from the complementary observations that: (1) conditions for the mitochondrial permeability transition pore (mPTP) opening are built up during early reperfusion, (2) mPTP opens at the time of reperfusion, (3) transgenic structural alteration of mPTP modifies its opening probability following ischemia-reperfusion, (4) mPTP plays a role in preconditioning, and (5) postconditioning attenuates lethal reperfusion injury. We review in this article current evidence for an important role of the mitochondrial transition pore in postconditioning.