间歇性高原低氧抗心肌缺血再灌注损伤的线粒体机制研究

发布时间：2018-08-17 17:16

【摘要】：目的:已有很多研究表明,间歇性高原低氧(Intermittent high altitude hypoxia,IHA hypoxia)能显著提高心肌抗缺血/缺氧的能力,表现为显著减轻缺血再灌注后心脏舒缩功能降低,减少缺血再灌注后心律失常的发生,缩小心肌梗死面积等。但对线粒体在低氧后的心肌保护中的作用研究甚少。本工作主要研究间歇性高原低氧对心肌线粒体的呼吸功能、线粒体通透性转换孔(MPTP)、线粒体KATP通道(mitoKATP)和线粒体蛋白质表达的影响以及它们在抗缺血再灌注损伤中的作用。方法:雄性SD大鼠随机分为常氧组(Normoxia)和间歇性高原低氧组,间歇性高原低氧组于低压氧舱接受42天相当5000m高度的减压低氧处理,每天6h。低氧暴露结束后,对照组和间歇性高原低氧组大鼠利用Langendorff灌流复制心肌缺血(30分钟)/再灌注(120分钟)损伤模型,观察记录心功能指标的变化;TTC法检测缺血再灌后心肌梗死面积;差速离心法分离左室心肌细胞线粒体,检测线粒体在不同Ca2+浓度的介质中A540的变化;Western Blotting测定细胞色素C从线粒体泄漏出的量;分离心肌细胞,用indo-1作为Ca2+的荧光指示剂,检测模拟缺血再灌注过程中细胞内和线粒体内钙的变化及心肌细胞舒缩活动的变化;用蛋白质组学方法研究间歇性高原低氧训练后心肌线粒体内蛋白质表达的变化。结果:在离体心脏Langendorff灌流实验中,观察到缺血再灌注抑制了常氧组大鼠心肌功能的恢复,间歇性高原低氧可以促进缺血再灌注后心功能的恢复,增加±dP/dt max和PRP,降低了LVEDP;同时还减少了缺血再灌注引起的心肌梗死面积;在复灌最初15分钟用特异性MPTP开放剂atractyloside(Atr)处理可以使这些保护性效应消失。间歇性高原低氧可降低缺血再灌注过程中心肌细胞内钙超载程度,复灌初用Atr处理可明显增加复灌时胞质和线粒体内钙超载水
[Abstract]:Objective: many studies have shown that intermittent high altitude (Intermittent high altitude hypoxia-IHA hypoxia can significantly improve the ability of myocardium to resist ischemia / hypoxia, as shown by a significant reduction of cardiac systolic and diastolic function after ischemia-reperfusion. Reduce the incidence of arrhythmia after ischemia reperfusion, reduce the size of myocardial infarction and so on. However, little research has been done on the role of mitochondria in myocardial protection after hypoxia. The purpose of this study was to investigate the effects of intermittent high altitude hypoxia on the respiratory function of myocardial mitochondria, the expression of mitochondrial KATP channel (mitoKATP) and mitochondrial protein in mitochondrial permeability transition pore (MPTP), and their role in the prevention of ischemia-reperfusion injury. Methods: male Sprague-Dawley rats were randomly divided into normoxic group (Normoxia) and intermittent high altitude hypoxia group (intermittent high altitude hypoxia group). The rats in intermittent high altitude hypoxia group were treated with hypobaric hypoxia at a height of 5000m for 42 days for 6 hours per day. After hypoxic exposure, myocardial ischemia (30 min) / reperfusion (120 min) injury model was induced by Langendorff perfusion in control group and intermittent high altitude hypoxia group. The mitochondria of left ventricular cardiomyocytes were isolated by differential centrifugation, the changes of mitochondria A540 in different concentrations of Ca2 were detected, the amount of cytochrome C leaked from mitochondria was determined by Western Blotting, and the myocardial cells were isolated with indo-1 as the fluorescent indicator of Ca2. The changes of intracellular and mitochondrial calcium and the activity of cardiomyocytes during simulated ischemia-reperfusion were detected. The protein expression in myocardial mitochondria after intermittent high altitude hypoxia training was studied by proteomics. Results: in the Langendorff perfusion experiment of isolated heart, it was observed that ischemia-reperfusion inhibited the recovery of myocardial function in normoxic rats. Intermittent high altitude hypoxia could promote the recovery of cardiac function after ischemia-reperfusion. Increased 卤dP/dt max and PRP decreased LVEDPand reduced myocardial infarction size induced by ischemia-reperfusion. These protective effects could be eliminated at the first 15 minutes after reperfusion treated with specific MPTP opener atractyloside (Atr). Intermittent high altitude hypoxia can reduce the degree of intracellular calcium overload in myocardial cells during ischemia-reperfusion. Atr treatment at the beginning of reperfusion can significantly increase intracellular calcium overload water in cytoplasm and mitochondria during reperfusion.
【学位授予单位】：中国科学院研究生院（上海生命科学研究院）
【学位级别】：博士
【学位授予年份】：2005
【分类号】：R363

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