线粒体ATP敏感性钾通道在七氟醚预处理减轻大鼠脑缺血再灌注损伤中的作用

目的 探讨线粒体ATP敏感性钾通道(mito-K_(ATP)通道)在七氟醚预处理减轻大鼠脑缺血再灌注损伤中的作用.方法 健康雄性SD大鼠100只,体重250～300 g,随机分为5组(n=20):假手术组(S组)、缺血再灌注组(I/R组)、七氟醚预处理组(Sevo组)、mito-K_(ATP)通道阻断剂5-羟基葵酸(5-HD)组及5-HD+七氟醚预处理组(5-HD+Sevo组).采用线栓法制备大鼠局灶性脑缺血再灌注模型,七氟醚预处理方法:吸入2.4%七氟醚60 min后吸入纯氧洗脱15 min,停止吸入七氟醚后24 h时制备脑缺血再灌注模型.分别于再灌注6、24 h时进行神经功能损伤评分,计算脑梗死体积百分比,采用Western blot法测定蛋白激酶Cε(PKCε)膜转位水平.结果 与S组比较,其余各组大鼠再灌注6、24 h时神经功能损伤评分升高,脑梗死体积百分比及脑组织PKCε膜转位水平升高(P<0.05);与I/R组、5-HD组及5-HD+Sevo组比较,Sevo组大鼠再灌注6、24 h时神经功能损伤评分降低,脑梗死体积百分比降低,再灌注6 h时脑组织PKCε膜转位水平升高(P<0.05).结论 mito-K_(ATP)通道介导了七氟醚预处理减轻大鼠局灶性脑缺血再灌注损伤的作用,其机制可能与调控PKCε膜转位有关.

Role of mitochondrial ATP-sensitive potassium channel in sevoflurane preconditioning-reduced focal cerebral ischemia-reperfusion injury in rats

Objective To investigate the role of the mitochondrial ATP-sensitive potassium (mito-K_(ATP)) channel in sevoflurane preconditioning-reduced focal cerebral ischemia-reperfnsion (I/R) injury in rats. Methods One hundred healthy 3-4 month old male SD rats 250-300 g were randomly assigned into 5 groups (n = 20 each) : group Ⅰ sham operatiun (group S); group Ⅱ I/R; group Ⅲ sevoflurane preconditioning (group Sevo); group Ⅳ 5-hydroxydecannate (5-HD) and group Ⅴ 5-HD + Sevo. Focal cerebral I/R was produced by mid-cerebral artery occlusion (MCAO) in group Ⅱ-Ⅴ . Cerebral ischemia was maintained for 2 h followed by 6 and 24 h reporfnsiun. In group Ⅲ and Ⅴ 2.4% sevoflurane in 97.6% O_2 was inhaled for 60 min at 24 h before MCAO. In group Ⅴ 5-HD (a selective mito-K_(ATP) channel antagonist) 40 mg/kg was given intraporitoneally (IP) at 30 min before sevoflurane preconditioning. In group Ⅳ 100% O_2 was inhaled instead of sevoflurune and 5-HD 40 mg/kg was given IP at 30 min before O_2 inhalation. Neurological deficit score (NDS, 0=no deficit, 7 = death) were measured at 6 and 24 h of reperfusion and the animals were then killed. Their brains were removed for determination of infaret size by TTC and cellular translocation of PKCε by Western blot analysis. Results NDS were significantly lower and brain infarct size was significantly smaller in group.Sevo (Ⅲ) than in I/R group (Ⅱ). The neuroprotection induced by sevoflurane preconditioning was reversed by 5-HD 40 mg/kg in group Ⅴ (5-HD + Sevo). There was no significant difference in infarct size and NDS among group Ⅱ , Ⅳ and Ⅴ . PKCε was activated and translocated to the membrane fraction at 6 h of reperfusion in group Sevo (Ⅲ) and this effect of sevoflurane was also abolished by 5-HD in group Ⅴ (5-HD + Sevo). Conclusion Scvoflurane preconditioning-induced neuroprotection is mediated by mito-K_(ATP) channel probably through regulating PKCε membrane translocation.