吡那地尔预处理对家兔常温高钾停跳离体心脏的影响

ATP敏感性钾通道(KATP通道)开放可能是缺血预处理(IP)发挥保护作用的重要机制。KATP通道开放剂能模拟IP开放KATP通道保护缺血的心肌，但KATP通道开放剂预处理在常温全心缺血与晶体心脏停搏液相结合的条件下是否发挥保护作用，尚无定论。本研究拟应用离体兔心Langendorff灌流模型观察心功能、心肌能量、脂质过氧化物含量及心肌形态学的改变，探讨钾通道开放剂吡那地尔预处理对常温高钾停跳液灌注离体兔心肌的保护效果，为常温体外循环心肌保护提供依据。     

过氧化物酶体增殖物激活受体-γ激动剂心肌保护作用机制的研究进展

背景过氧化物酶体增殖物激活受体（peroxisome proliferator-activated receptors,PPARs）主要参与和能量代谢及炎症反应相关的基因转录。其1亚型除作为治疗2型糖尿病的降糖靶点外,在心肌缺血／再灌注损伤（myocardial ischemia／reperfusion injury,MI／RI）中也具有关键作用,是减轻MI／RI、维持心脏功能的重要因子。目的探究过氧化物酶体增殖物激活受体-γ（peroxisome proliferator-activatedreceptor-γ,PPAR-γ）激动剂在MI／RI中心肌保护作用的相关机制。内容从PPAR-γ及其激动剂和相关实验研究等方面进行综述,PPAR-y激动剂能够通过依赖和不依赖PPAR-γ两条途径减少心肌梗死面积,改善心脏功能,发挥减轻MI／RI的作用,其中涉及抗炎、抗氧化、抗凋亡等多种重要保护机制。趋向深入研究PPAR激动剂减轻MI／RI的具体机制可为临床提供新的心肌保护策略。     

线粒体ATP敏感性钾通道不参与异丙酚预处理的心肌保护

应用药物预处理减轻心肌缺血，再灌注损伤的报道已有很多，有报道许多药物心肌保护作用机制是通过开放线粒体KATP。有研究显示线粒体KATP开放剂能够减轻心肌缺血，再灌注损伤，但肌膜KATP不参与线粒体KATP开放剂引起的心肌保护。还有报道异丙酚预处理对离体心脏具有保护作用。但是异丙酚预处理的心肌保护机制是否也是通过开     

ATP敏感性钾通道与心肌保护

ATP敏感性钾通道（KATP）可调节细胞对组织缺血、缺氧的耐受性，介导并参与细胞或组织的保护作用。本文介绍KATP通道及其与心肌保护之间的关系。     

吗啡对大鼠心肌缺血/再灌注损伤的保护作用

目的 探讨吗啡对离体大鼠心肌缺血/再灌注损伤的保护作用和机制。方法 建立离体大鼠心脏灌注模型。TTC染色梗死心肌。观察缺血/再灌注后,吗啡对冠脉流量（CF）、心率（HR）、左室压力（LVP）、左室压力最大变化速率（LVP/dtmax）及心梗范围的影响,并观察纳洛酮和glibenclamide对吗啡作用的影响。结果 缺血/再灌注后,离体大鼠心脏的CF、HR、LVP和LVP/dtmax显著下降（P<0.01）。缺血前给予吗啡可以使缺血/再灌注后HR、LVP和LVP/dtmax显著恢复（P<0.01）,心梗范围显著缩小（P<0.01）。吗啡不能增加缺血/再灌注后离体大鼠心脏的CF（P>0.05）。分别给予纳洛酮和glibenclamide可以完全取消吗啡的心肌保护作用。结论 吗啡可以减轻大鼠心肌的缺血/再灌注损伤。吗啡是通过心肌局部的阿片受体及心肌细胞的KATP通道介导产生心肌保护作用。     

微RNA参与七氟醚减轻心肌缺血/再灌注损伤的作用机制研究进展

微RNA (microRNA, miRNA）是心肌缺血/再灌注损伤（myocardial ischemia/reperfusion injury, MI/RI）机制中的主要调节元件。七氟醚可通过调节miRNA的表达减轻MI/RI。文章对参与七氟醚心肌保护作用的miRNA相关机制研究进展进行综述,分别论述参与七氟醚预处理...     

ATP敏感性钾通道与心肌保护

ATP敏感性钾通道(KATP)可调节细胞对组织缺血、缺氧的耐受性,介导并参与细胞或组织的保护作用。本文介绍KATP通道及其与心肌保护之间的关系。     

挥发性麻醉药后处理保护缺血/再灌注心肌的研究进展

缺血后处理（ischemic postconditioning）是近年来提出的一种新的心肌保护方法,即心肌缺血后在长时间的再灌注之前,进行的数次短暂再灌注／缺血的循环。实验证明后处理对缺血心肌确有显著的保护作用。挥发性麻醉药后处理也可以发挥同样的保护效应,其机制比较复杂,远未阐明,现就其保护作用的机制作一综述。     

药物后处理对心肌缺血/再灌注损伤保护作用的研究与展望

背景随着心肌缺血/再灌注损伤（ischemia/reperfusion injury,I/RI）机制及心肌保护机制研究的深入,药物后处理作为一种更具有临床实用价值的心肌保护方法成为了研究热点。 目的阐述药物后处理用于心肌保护时,相关药物所模拟内源性保护机制的主要环节以及近年来药物后处理的研究概况和前瞻。 内容介绍药物后处理用于心肌保护时,主要途径、作用靶点以及相关药物。趋势药物后处理心肌保护机制的研究和深入将会发现更多的药物靶点,独特的操作便利性,必将更好的应用于临床服务于患者。     

线粒体三磷酸腺苷敏感性钾通道在未成熟心肌缺血预处理中的作用

目的探讨线粒体三磷酸腺苷敏感性钾通道（mitoKATP）在未成熟心肌预处理保护中的作用,为未成熟心肌的保护提供依据。方法采用Langendorff离体心脏灌注模型,将24只新生（出生14～21d）日本长耳大白兔按随机数字表法分为4组：缺血／再灌注组（I／R组）,心脏缺血预处理组（E1组）,mitoKATP阻滞剂5-hydroxydecanoate（5-HD）＋心脏缺血预处理（E2组）,mitoKATP通道开放剂Diazoxide（Diaz）预处理组（E3组）;检测心脏功能恢复率、心肌含水量、血清肌酸激酶和乳酸脱氢酶漏出率、三磷酸腺苷（ATP）含量、超氧化物歧化酶活性、丙二醛含量、心肌细胞内Ca^2＋含量、心肌线粒体Ca^2＋含量、心肌线粒体Ca^2＋-三磷酸腺苷酶活性（Ca^2＋-ATPase）、心肌线粒体合成ATP的能力;电子显微镜观察心肌超微结构。结果E1组、E3组心功能恢复优于I／R组和E2组,心肌含水量低于I／R组和E2组（P〈0．05）;E1组、E3组三磷酸腺苷含量、超氧化物歧化酶活性、心肌线粒体Ca^2＋-ATPase活性、心肌线粒体合成ATP的能力均优于I／R组和E2组（P〈0．05）,丙二醛含量、血清肌酸激酶和乳酸脱氢酶漏出率、心肌细胞内Ca^2＋含量、心肌线粒体Ca^2＋含量低于I／R组、E2组（P〈0．05）;E1组、E3组心肌超微结构损伤较I／R组和E2组明显减轻。结论心肌缺血预处理对未成熟心肌具有明显的保护作用,其机制可能是通过mitoKATP通道的开放起作用。     

降钙素基因相关肽对心肌缺血/再灌注损伤保护作用信号通路研究进展

背景 降钙素基因相关肽(calcitonin gene-related peptide,CGRP)是一种重要的感觉神经肽,能减轻心肌缺血/再灌注损伤(myocardial ischemia/reperfusion injury,MI/RI). 目的 就CGRP发挥心肌保护作用的信号通路进行综述. 内容 概述CGRP的生物学特征、对MI/RI的影响以及所涉及的信号通路. 趋向 研究CGRP对MI/RI的信号转导机制有助于阐明CGRP对心肌保护的重要性,并提供新的治疗靶点.     

低氧诱导因子-1/低氧反应元件通路在心肌保护中的研究进展

背景 低氧诱导因子-1 (hypoxia inducible factor-1,HIF-1)是目前公认的在缺氧状态下发挥重要作用的核转录因子,其活化后可介导低氧反应保护作用,在一定程度上能够减轻心肌的缺血/再灌注损伤(ischemic reperfusion injury,I/RI).目的 探究HIF-1/低氧反应元件(hypoxia response element,HRE)通路是如何被激活并发挥心肌保护的作用. 内容 从HIF-I的概述、调节以及HIF-1/HRE通路的激活机制及其心肌保护作用方面进行综述,并以HIF-1为靶点探究后处理的心肌保护作用的机制,对其在心肌保护作用中与其他关键性的转录因子之间的内在联系作一简要综述. 趋向 后处理能否激活HIF-1/HRE通路诱导红细胞生成素(erythropoietin,EPO)、血红素加氧酶1(hemeoxygenase1,HO-1)、诱导型一氧化氮合酶(inducible nitric oxide synthase,iNOS)和血管内皮生长因子(vascular endothelial growth factor,VEGF)等保护性蛋白的表达,以减轻心肌I/RI,尚需进一步探讨.     

七氟醚对心肌缺血/再灌注损伤的临床研究进展

背景 七氟醚的心肌保护作用得到广泛关注,大量基础研究表明七氟醚对心肌缺血/再灌注损伤(myocardial ischemia/reperfusion injury,MI/RI)具有确切的保护作用.然而,临床中关于七氟醚具有心肌保护作用的结论尚未完全统一.目的 通过总结近年的研究进展对七氟醚的心肌保护作用进行阐述.内容 不同心脏手术及非心脏手术中七氟醚药物处理的心肌保护效果.趋向 今后仍需加强对七氟醚心肌保护作用的临床研究,为围手术期患者的心肌保护提供更为可靠的理论依据.     

心肌缺血/再灌注损伤中微小RNA的作用研究进展

背景 心肌缺血/再灌注损伤(ischemia/reperfusion injury,I/RI)是临床最常见的损伤之一,微小RNA(microRNA,miRNA)参与了其进程. 目的 对心肌I/RI过程中miRNA作用的最新进展进行综述. 内容 回顾并展望miRNA在心肌缺血/再灌注中的作用. 趋向 miRNA与心肌I/RI密切相关,更多以miRNA为靶点的治疗会被用于心肌保护.     

ATP sensitive potassium channel and myocardial preconditioning

KATP channels play an important role in physiology and pathophysiology of many tissues. As in the pancreatic beta cells, they couple the change of blood glucose with insulin release. The data coming from Baukrowitz et al. and Shyng and Nichols gave the possible answers to the two old enigmas of KATP channels, i.e., different ATP sensitivity reported in the same tissue and how the channel opened under intracellular millimolar ATP concentration, in which they showed the lipids and lipid metabolites are essential for KATP channel regulation by altering ATP sensitivity. This new information rises several further considerations. How does PIP2 reduce the sensitivity of the channel to ATP? In order to clarify the possibility of direct competing or allosteric effect on the ATP binding site, competitive binding assay should be performed. Since the PIP2 theory seems to be the key event to determine the ATP sensitivity and thus control the channel open probability, then what is the resting concentration of PIP2 in the cell membrane? Is it sufficient to account for the difference in the ATP sensitivity of the intact cell and excised patch from different tissues? Quantitative studies either immunoblotting by PIP2 antibody or fluorescence-labeled lipid assay-may obtain some basic but useful data for further studies to answer these questions. Furthermore, the ATPi mediated restoration of activity was inhibited by antibodies against PIP2. The dualistic behavior of KATP channels to intracellular NDPs should be reexamined with respect to PIP2. The vast majority of preconditioning studies has been performed in intact animals in which myocardial infarct size was used as the end point to define the cardio-protective effect of ischemic PC. These results suggest a key role for the KATP channel as both a trigger and as an end effector of both acute and delayed ischemic PC. The persistent activation of KATP channels during the early reperfusion phase is essential for a smooth and full recovery of contractile function, as well as for maintenance of electrical stability in heart that has been exposed to ischemia. Though activate adenosine A1 receptor coupled with Gi protein can open the KATP channels, adenosine is quickly released during ischemia and exerts potent coronary vasodilatation to maintain coronary blood flow through A2 receptors. This adenosine-induced coronary vasodilatation could be coupled with KATP channels based on the evidence of the augmentation effect of KCOs. Nitric oxide may also play some role in both first and second window of myocardial protection. It is possible that rapid and reversible phosphorylation and activation of constitutive expressed myocardial NOS or by direct KATP channel phosphorylation and activation leads to the first window of myocardial protection. This hypothesis can be further investigated either by using site direct mutagenesis of iNOS or KATP channel, or by applying the dominant negative iNOS in the cell ischemic model, or by building the adenosine or iNOS knock-out mice to study the relationship of these possible mechanisms. Recently, Kontos further showed that KCOs need L-lysine or L-arginine to dilate cerebral arterioles. This suggests that there may be an amino acid binding site inside the KATP channel and nitric oxide can open the KATP channel either by direct acting on the channel protein or by modulating the affinity of the amino acid binding site for L-lysine or L-arginine. Other KATP channel openers in need of additional characterization are the Type III KCOs (nicorandiol). They open the KATP channel only in the presence of elevated intracellular NDPs, which may make them specifically target to the ischemic region, because the intracellular NDP increases mostly in ischemic region. It is possible that type III KCOs can selectively improve blood flow to ischemic areas without diverting blood away to non-ischemic region, and prevents the "steal phenomenon". (ABSTRACT TRUNCATED)     

炎症反应在心肌缺血/再灌注损伤中作用的研究进展

背景 心肌缺血/再灌注损伤(ischemia/reperfusion injury,I/RI)是指在缺血心肌恢复血流灌注后,细胞代谢功能障碍和结构破坏反而加重的现象,并且伴随有以炎症细胞浸润和细胞因子产生为特征的炎症反应.目前认为,炎症反应是I/RI的重要病理机制之一,再灌注诱发的炎症反应及其介质可加重心肌I/RI,而...     

含钾通道开放剂的HTK液对大鼠心功能以及线粒体结构和功能的影响

目的 观察含钾通道开放剂的供心保存液对心功能以及能量代谢、线粒体呼吸酶活性及超微结构的影响.方法 将SD大鼠分为HTK组、Pi组、5HD组、1098组和5HD+1098组.切取SD大鼠心脏,建立Langendorff灌注模型,平衡10 min,然后按分组进行如下处理:HTK组心脏以Histidine-Tryptophan-Ketoglutarate液(HTK液)停搏;Pi组心脏以含0.5 mmol/L吡那地尔(Pi)的HTK液停搏;1098组心脏以含0.5 mmol/L Pi和100 μmol/L HMR1098的HTK液停搏;5HD组心脏以含0.5 mmol/L Pi和100 μmol/L五羟葵酸(5HD)的HTK液停搏;5HD+1098组心脏以含0.5 μmol/L Pi、100 μmol/L 5HD和100μmol/L HMR1098的HTK液停搏.停搏后,将心脏置于各组相应的液体(4℃)中保存8 h,然后用含氧的37℃克-亨液(K-H液)再灌注60 min.观察各组平衡末、保存末、再灌注末时的心功能、线粒体呼吸酶活性、心肌ATP含量及心肌细胞线粒体超微结构的改变.结果 Pi组保存末、再灌注末的心功能(心率、左心室舒张末压、左心室发展压和冠状动脉流量)、心肌线粒体呼吸酶(NADH氧化酶、琥珀酸氧化酶、细胞色素C氧化酶)活性及ATP含量均优于其他各组(P<0.01或P<0.05),同时线粒体的结构改变也最轻.结论 含Pi的HTK液能改善大鼠心脏保存效果;Pi对能量状态的维持以及对线粒体结构与功能的保护可能是其心肌保护的重要机制.     

促红细胞生成素对缺血/再灌注心肌保护作用的研究进展

背景 促红细胞生成素(erythropoietin,EPO)是一种造血刺激因子,过去20多年中用于临床多种原因所致的贫血.随着对EPO及其受体在心血管方面作用的认识,增加了EPO在生理和病理生理方面作用的理解. 目的 将心肌缺血/再灌注损伤(ischemia/reperfusion injury,I/RI)减轻到最低限度. 内容 研究EPO在心脏中的表达及其在心肌保护中所涉及的传导机制,EPO在动物心血管疾病实验模型中起到心肌保护作用及目前EPO心肌保护作用的临床相关研究. 趋向 近年来,EPO心肌保护作用临床研究的报道逐渐增多,为临床心肌保护提供了新的方向,但需要更深入研究EPO的心肌保护作用.     

Calcium preconditioning, but not ischemic preconditioning, bypasses the adenosine triphosphate-dependent potassium (KATP) channel.

BACKGROUND: Recent evidence has implicated the KATP channel as an important mediator of ischemic preconditioning (IPC). Indeed, patients taking oral sulfonylurea hypoglycemic agents (i.e., KATP channel inhibitors) for treatment of diabetes mellitus are resistant to the otherwise profoundly protective effects of IPC. Unfortunately, many cardiopulmonary bypass patients, who may benefit from IPC, are chronically exposed to these agents. Calcium preconditioning (CPC) is a potent form of similar myocardial protection which may or may not utilize the KATP channel in its mechanism of protection. The purpose of this study was to determine whether CPC may bypass the KATP channel in its mechanism of action. If so, CPC may offer an alternative to IPC in patients chronically exposed to these agents. METHODS: Isolated rat hearts (n = 6-8/group) were perfused (Langendorff) and received KATP channel inhibition (glibenclamide) or saline vehicle 10 min prior to either a CPC or IPC preconditioning stimulus or neither (ischemia and reperfusion, I/R). Hearts were subjected to global warm I/R (20 min/40 min). Postischemic myocardial functional recovery was determined by measuring developed pressure (DP), coronary flow (CF), and compliance (end diastolic pressure, EDP) with a MacLab pressure digitizer. RESULTS: Both CPC and IPC stimuli protected myocardium against postischemic dysfunction (P < 0.05 vs I/R; ANOVA with Bonferroni/Dunn): DP increased from 52 +/- 4 (I/R) to 79 +/- 2 and 83 +/- 4 mmHg; CF increased from 11 +/- 0.7 to 17 +/- 2 and 16 +/- 1 ml/min; and EDP decreased (compliance improved) from 50 +/- 7 to 27 +/- 5 and 31 +/- 7 mmHg. However, KATP channel inhibition abolished protection in hearts preconditioned with IPC (P < 0.05 vs IPC alone), but not in those preconditioned with CPC (P > 0.05 vs CPC alone). CONCLUSIONS: (1) Both IPC and CPC provide similar myocardial protection; (2) IPC and CPC operate via different mechanisms; i.e., IPC utilizes the KATP channel whereas CPC does not; and (3) CPC may offer a means of bypassing the deleterious effects of KATP channel inhibition in diabetic patients chronically exposed to oral sulfonylurea hypoglycemic agents.