七氟醚后处理对大鼠离体心脏缺血再灌注时心肌细胞p70S6K表达的影响

Effects of sevoflurane postconditioning on expression of cardiomyocyte p70S6K during ischemia-reperfusion in isolated rat hearts

目的 评价七氟醚后处理对大鼠离体心脏缺血再灌注时心肌细胞核糖体40S小亚基蛋白S6激酶（p70S6K）表达的影响.方法 取Langendorff心脏模型制备成功的大鼠心脏90个,采用随机数字表法分为3组（n=30）：假手术组（S组）、缺血再灌注组（I/R组）和七氟醚后处理组（SP组）.离体心脏缺血30 min,再灌注2h.SP组于缺血末至再灌注15 min灌注经3.0％七氟醚饱和的K-H液,随后更换为正常K-H液再灌注105 min.于再灌注2h时测定心肌梗死体积,计算心肌梗死体积百分比,采用Western blot法检测心肌细胞p-p70S6K/t-p70S6K、细胞质和线粒体细胞色素c和caspase-8的表达水平.结果 与S组比较,I/R组心肌梗死体积百分比升高,心肌细胞p-p70S6K/t-p70S6K、细胞质细胞色素c和caspase-8表达上调,线粒体细胞色素c表达下调（P＜0.05）;与I/R组比较,SP组心肌梗死体积百分比降低,心肌细胞p-p70S6K/t-p70S6K和线粒体细胞色素c表达上调,细胞质细胞色素c和caspase-8表达下调（P＜0.05）.结论 七氟醚后处理可减轻离体大鼠离体心脏缺血再灌注损伤,其机制与上调心肌细胞p-p70S6K表达,抑制线粒体细胞色素c转移至细胞质,从而减少细胞凋亡有关.

Objective To evaluate the effects of sevoflurane postconditioning on the expression of 70 kD aribosomalprotein S6 kinase （p70S6K） during ischemia-reperfusion （I/R） in isolated rat hearts.Methods Pathogen-free male Sprague-Dawley rats,aged 3 months,weighing 270-350 g,were used in the study.Their hearts were excised and perfused in a Langendorff apparatus with K-H solution saturated with 95 % O2-5 % CO2.Ninety isolated rat hearts with I/R injury were randomly divided into 3 groups （n =30 each）：sham operation group （group S）,I/R group （group I/R）,and sevoflurane postconditioning group （group SP）.The hearts were subjected to ischemia for 30 min followed by 2 h reperfusion.In group SP,the hearts were perfused with K-H solution saturated with 3.0% sevoflurane for 15 min starting from the end of ischemia until 15 min of reperfusion,and then with plain K-H solution for 105 min.At 2 h of reperfusion,myocardial infarct size was measured,the percentage of myocardial infarct size was calculated,and the phosphorylated p70S6K （p-p70S6K）/total p70S6K （tp70S6K） ratio,and cytoplasm,cytochrome C,and caspase-8 expression was measured.Results Compared with group S,the percentage of myocardial infarct size and p-p70S6K/t-p70S6K ratio were significantly increased,the expression of cytochrome C,and caspase-8 was up-regulated,and the expression of cytochrome C was downregulated in I/R group.Compared with I/R group,the percentage of myocardial infarct size was significantly decreased,the ratio of p-p70S6K/t-p70S6K was increased and cytochrome C expression was up-regulated,and the expression of cytochrome C and caspase-8 was down-regulated in SP group.Conclusion Sevoflurane postconditioning can mitigate I/R injury to isolated rat hearts,and up-regulation of p-p70S6K expression,inhibition of transfer of cytochrome C from mitochondria to cytoplasm,and reduced cell apoptosis are involved in the mechanism.