蛋白激酶C在缺血预处理减轻大鼠心肌缺血再灌注时线粒体损伤中的作用

Role of protein kinase C in reduction of mitochondrial injury during myocardial ischemia-reperfusion by ischemic preconditioning in rats

目的：评价蛋白激酶C （PKC ）在缺血预处理减轻大鼠心肌缺血再灌注时线粒体损伤中的作用。方法雄性SD大鼠40只，12～13周龄，体重280～320 g ，采用随机数字表法，将其分为4组（ n＝10）：假手术组（S组）、缺血再灌注组（I/R组）、缺血预处理组（IPC组）和PKC抑制剂白屈菜红碱组（C组）。采用结扎左冠状动脉前降支35 min ，再灌注120 min的方法建立心肌缺血再灌注损伤模型。IPC组于缺血前即刻缺血5 min ，再灌注5 min ，重复3次，行缺血预处理。C组于缺血预处理前尾静脉注射PKC抑制剂白屈菜红碱1 mg/kg。再灌注120 min时处死大鼠取心肌组织，分离线粒体，制备线粒体悬液，测定琥珀酸脱氢酶（SDH）、黄嘌呤氧化酶（XOD ）、谷胱甘肽过氧化物酶（GSH-Px ）和Ca2＋-ATP酶的活性、Ca2＋含量、线粒体通透性转换孔（mPTP ）开放程度和膜电位（Δψm ）。结果与S组比较，I/R组线粒体XOD、Ca2＋-ATP酶活性、Ca2＋含量、mPTP开放度升高，线粒体SDH、GSH-Px的活性、Δψm降低（ P＜0.05）；与I/R组比较，IPC组线粒体XOD、Ca2＋-ATP酶活性、Ca2＋含量和mPTP开放度降低，SDH、GSH-Px的活性、线粒体Δψm升高（ P＜0.05）；与IPC组比较，C组线粒体XOD、Ca2＋-ATP酶活性、Ca2＋含量和mPTP开放度升高，线粒体SDH、GSH-Px的活性、Δψm降低（ P＜0.05）。结论 PKC参与了缺血预处理减轻大鼠心肌缺血再灌注时的线粒体损伤。

Objective To evaluate the role of protein kinase C （PKC ） in reduction of mitochondrial injury during myocardial ischemia-reperfusion （I/R） by ischemic preconditioning in rats .Methods Forty male Sprague-Dawley rats ,aged 12-13 weeks ,weighing 280-320 g ,were randomly divided into 4 groups （ n=10 each） using a random number table：sham operation group （S group） ,I/R group ,ischemic preconditioning group （IP group） and PKC inhibitor chelerythrine group （C group） .Myocardial I/R was produced by 35 min occlusion of left anterior descending branch of coronary artery followed by 120 min reperfusion .Ischemic preconditioning was induced by 3 episodes of 5 min occlusion of left anterior descending branch at 5 min intervals before myocardial ischemia . Chelerythrine 1 mg/kg was injected intravenously via the caudal vein before ischemic preconditioning in group C . At 120 min of reperfusion ,the animals were sacrificed and the hearts were immediately removed .Mitochondrial suspension was prepared for determination of activities of succinate dehydrogenase （SDH ） , xanthine oxidase （XOD ） , glutathione peroxidase （GSH-Px ） and Ca2＋-ATPase , content of Ca2＋ , myocardial mitochonerial permeability transition pore （mPTP） opening and membrane potential （Δψm ） .Results Compared with S group , the activities of XOD and Ca2＋-ATPase ,content of Ca2＋ and mPTP opening were significantly increased ,and the＆nbsp;activities of SDH and GSH-Px and Δψm were decreased in I/R group （ P〈0.05） .Compared with I/R group ,the activities of XOD and Ca2＋-ATPase , content of Ca2＋ and mPTP opening were significantly decreased , and the activities of SDH and GSH-Px and Δψm were increased in IP group （ P〈0.05） .Compared with IP group ,the activities of XOD and Ca2＋-ATPase , content of Ca2＋ and mPTP opening were significantly increased , and the activities of SDH and GSH-Px and Δψm were decreased in C group （ P〈0.05） .Conclusion PKC is involved in reduction of mitochondrial injury during myocardial I/R by ischemic preconditioning in rats .