【作者】 边云飞；

【导师】 吴博威；

【作者基本信息】 山西医科大学 ， 生理学， 2005， 博士

【摘要】 近年来,随着临床冠脉内溶栓、PTCA 及冠脉搭桥术等治疗手段的广泛应用,心肌再灌注损伤愈来愈引起人们的广泛重视。缺血预适应是目前认为最强及最有效的内源性保护机制,一系列研究均显示缺血预适应可以显著减轻心肌缺血再灌注损伤。但是由于在临床治疗中经常遇到的是已经发生的心肌缺血,而真正能够干预的是已发生的心肌缺血阶段及再灌注阶段,因而从临床治疗的角度讲,缺血预适应的真正临床应用价值有很大的局限性。2003 年, Zhao 首先在狗的模型发现缺血后适应现象。之后,这一现象在大鼠和兔子的模型上也相继得到了证实。由于缺血后适应的干预应用于缺血发生之后和再灌注之前,具有广泛的临床应用前景,因而引起了人们的广泛关注。缺血后适应发现后,如何建立有效的药物后适应途径,并分析其发生机制,已经提到研究日程。考虑到激活线粒体内膜KATP通道在缺血预适应中的心肌保护作用已被公认,而它的选择性激动剂二氮嗪又是一可用于临床的药物,因此我们在预实验的基础上,首先选择二氮嗪在动物建立药物后适应模型,并进一步分析在药物后适应和模拟缺血后适应中激活KATP通道产生心肌保护作用的机制,为进一步的临床研究和应用奠定基础。一、二氮嗪药物后适应对离体大鼠心肌局部缺血/再灌注损伤的影响目的:观察二氮嗪药物后适应,即在再灌注早期激活线粒体ATP 敏感性钾通道对缺血/再灌注心肌的保护作用。材料与方法:利用Langendorff 逆行灌流装置对大鼠心脏离体灌流,通过对左冠状动脉前降支的结扎和松扎建立大鼠离体心脏局部缺血/再灌注模型。实验分为11 组:1 组,缺血/再灌注组。Ⅱ组,二氮嗪药物后适应组,并包括Ⅱa、Ⅱb、Ⅱc三个不同药物剂量组。Ⅲ组,pinacidil 药物后适应组。Ⅳ组,二氮嗪药物预适应组。Ⅴ组,二氮嗪加5-HD 药物后适应阻断组。Ⅵ组,二氮嗪加优降糖药物后适应组。Ⅶ组,二氮嗪加优降糖及5-HD药物后适应组。Ⅷ组,二氮嗪加atractyloside 药物后适应阻断组。Ⅸ组,更多还原

【Abstract】 With increasing application of PTCA, CABG, intracoronary thrombolisis in acute myocardial infarction in recent years, myocardial ischemic and reperfusion injury has attracted considerable attention. Ischemic preconditioning has been proved to exert extensive protection to ischemic and reperfusion myocardium, including attenuation of myocardial cell death or apoptosis. However, as its name implies, ischemic preconditioning must be applied before an ischemic event to be protective, thus limiting its utility. It is of great encourage that Zhao et al first reported in 2003 that multiple brief periods reperfusion and ischemic intervention before reperfusion, called ischemic postconditioning, significantly reduced infarct size in dog heart model. The ischemic postconditioning phenomenon was also confirmed by Kin in rat model and Yan in rabbit model in the following research. Because ischemic postconditionong was applied after an ischemic event, it has greatly clinical appeal. After ischemic postconditioning phenomenon was recognized, it is of great significance to establish effective pharmacological postconditioning and explore possible mechanisms underling it . Considerating that mitochondrial KATP(mito KATP) channels have a critical role in cardioprotection of ischemic preconditioning and that diazoxide, which is a selected agonist of mito KATP, can be applied to clinical treatment, the present study intends to firstly establish diazoxide pharmacological postconditioning Furthermore,we explore the mechanism. underling the diazoxide pharmacological postconditioning and mimic ischemic postconditioning medicated cardioprotective effect by activation of KATP channel, which lay strong basis for future clinical study. Part ⅠProtective effect of diazoxide pharmocological postconditioning on myocardial regional ischemia/reperfusion injury in isolated rat heart Objective To test whether and how diazoxide pharmacological postconditioning might protect myocardium against ischemic and reperfusion injury. Materials and Methods An isolated myocardial regional ischemic/reperfusion rat model was established. Briefly, Wistar rat was sacrificed and heart was mounted on a Langendorff apparatus and retrogradely perfused with Tyrode’s solution. Then the isolated hearts underwent regional ischemia by ligaturing the left anterior descending (LAD) coronary artery and reperfusion by releasing the ligature. All hearts were divided into 11 groups: group Ⅰ, myocardial ischemic/reperfusion group ; group Ⅱ, diazoxide pharmacological postconditioning group , which was further devided into 3 dosage groups, Ⅱa,Ⅱb and Ⅱc groups; group Ⅲ, pinacidil pharmacological postconditioning group; group Ⅳ, diazoxide pharmacological preconditioning group; groupⅤ, diazoxide+5-HD pharmacological postconditioning group; group Ⅵ, diazoxide + glybenclamide pharmacological postconditioning group ; group Ⅶ, diazoxide + glybenclamide +5-HD pharmacological postconditioning group ; group Ⅷ, diazoxide + atractyloside pharmacological postconditioning group; group Ⅸ, diazoxide + GF 109203X pharmacological postconditioning group; group Ⅹ, PMA pharmacological postconditioning group; group Ⅺ, PMA + 5-HD postconditioning group . After completing perfusion, infarct size (NBT Staining), the leakage of CK were measured, and recovery of cardiac function at the end of reperfusion was also evaluated. Result (1) In groupⅠ(myocardial ischemic reperfusion group),myocardial infarct size(myocardial infarct size/total left ventricular size)was 44.4±0.9% . Compared with group Ⅰ, infarct sizes in different pharmacological postconditioning decreased to different levels: groupⅡa (diazoxide 10μmol/Lpharmacological postconditioning group) (36.2±0.7%), groupⅡb (diazoxide30 μmol/L pharmacological postconditioning group) (32.2±0.4%), group Ⅱc (diazoxide 60μmol/L pharmacological postconditioning group)( 22.2±2.1%), group Ⅲ( pinacidil pharmacological postconditioning group)( 35.2±2.2%), group Ⅹ(PMA pharmacological postconditioning group)( 31.2 ±1.9). Each of the a更多还原