缺血预处理对大鼠离体心脏心肌线粒体功能的影响

Protective effects of ischemic preconditioning on mitochondrial function in isolated rat hearts

目的研究缺血预处理（IPC）对大鼠离体心脏心肌线粒体功能的影响。方法SD大鼠72只，随机分为4组（n=18）：对照组（CON组）、缺血再灌注组（IR组）、缺血预处理组（IPC组）和5-羟葵酸（5-HD）拮抗IPC组（5-HD＋IPC组）。采用Langendorff装置建立大鼠离体心脏缺血再灌注模型，IPC组在全心停灌前，给予2次缺血预处理，每次缺血5min，间隔5min；5-HD＋IPC组预处理前灌注5-HD 10min。各组于平衡末、缺血前、再灌注30min各取6个心脏，分离心肌线粒体并测定线粒体呼吸控制率（RCR）、磷氧比（ADP／O2）、NADH氧化酶（NADH-OX）、琥珀酸氧化酶（SUC-OX）、细胞色素C氧化酶（CYTC-OX）的活性。结果与CON组比较，IR组、IPC组和5-HD＋IPC组再灌注30min RCR、ADP／O2、NADH-OX、SUC-OX和CYTC＋OX的活性降低（P〈0．05）；与IR组比较，IPC组和5-HD＋IPC组再灌注30min上述各指标升高（P〈0．05）；与IPC组比较，5-HD＋IPC组再灌注30min上述各指标降低（P〈0．05）。结论缺血预处理可改善大鼠离体心脏缺血再灌注时心肌线粒体的功能，其机制与mitoKATP的激活有关。

Objective To investigate the protective effects of ischemic preconditioning （IPC） on mitochondrial function in isolated rat hearts. Methods Seventy-two SD rats of both sexes weighing 200-250 g were randomly divided into 4 groups （ n = 18 each） ： group Ⅰ control; groupⅡ I/R; group m iPC ＋ I/R and group Ⅳ 5-HD ＋ IPC ＋ I/R. The animals were anesthetized with intraperitoneal pentobarbital 30 mg/kg . The hearts were immediately excised and perfused with oxygenated （95% 02- 5 % CO2 ） K-H buffer in a Langendorff apparatus. In I/R group the hearts were perfused for 30 min before 40 min global ischemia induced by suspension of perfusion followed by 30 min reperfusion. In IPC group （group Ⅲ ） the hearts were subjected to 2 episodes of 5 min ischemia at 5 min intervals before ischemia. In group Ⅳ the hearts were perfused with 5-HD for 10 min before IPC. Six hearts were taken and mitochondria were extracted at the end of post-preparation equilibration , immediately before ischemia and at the end of 30 min reperfusion for determination of mitochondrial respiratory control rate （RCR）, ADP/O2, the activities of mitochondrial NADH oxidase, succinate oxidase and cytochrome C oxidase. Results The mitochondrial RCR, ADP/O2, the activities of mitochondrial NADH oxidase, succinate oxidase and cytochrome C oxidase were significantly decreased in group I/R （ Ⅱ ）, IPC （ Ⅲ ） and 5-HD ＋ IPC （ Ⅳ ） as compared with control group （ Ⅰ ）. IPC attenuated the decrease in mitochondrial function induced by I/R. The protective effect of IPC against I/R injury was partially counteracted by 5-HD. Conclusion IPC can protect myocardial mitochondria from I/R injury and the protective effect of IPC can be partially related to mitochondrial ATP-sensitive potassium channels activation.