磷脂酰肌醇3激酶信号通路在缺血后适应中对大鼠心肌保护机制的研究

Mechanism of cardioprotective effect of PI3K/Akt pathway in ischemic postconditioning on rat myocardium

目的研究缺血后适应(IPost)对大鼠心肌保护作用及磷脂酰肌醇3激酶(PI3K/Akt)信号通路机制。方法将32只雄性Wistar大鼠随机分为缺血再灌注组(A组),IPost组(B组),IPost+Wortmannin组(C组)和缺血再灌注+SB216763组(D组),每组8只。测定各组左心室收缩压(LVSP)和再灌注30 min冠状动脉流出液中乳酸脱氢酶和肌酸激酶含量。并测定心肌梗死面积,对心肌进行免疫组织化学染色,观察Akt磷酸化和GSK-3β磷酸化的表达。结果与B组比较,A组LVSP明显降低,乳酸脱氢酶和肌酸激酶含量明显升高(P<0.05);同时IPost干预减小了心肌梗死面积(47.3% vs 29.5%),B组Akt磷酸化和GSK-3β磷酸化表达增加。结论 IPost对体外大鼠缺血再灌注损伤有明确的保护作用。Wortmannin可削弱IPost的保护作用,SB216763具有模拟IPost的心肌保护作用,Akt和GSK-3β的磷酸化水平在IPost的心肌保护作用信号通道传导机制中具有重要地位。

Objective To explore the cardioprotective effect of isehemic postconditioning（IPost） on rat myocardium and the mechanism of PI3K/Akt signal pathway in IPost. Methods Thirty-two healthy adult male Wistar rats were assigned randomly to ischemia/reperfusion group（group A）, IPost group（group B）, IPost＋Wortmannin group（group C）, I/R＋SB216763 group（group D）, each group had eight rats. The cardiac injury was evaluated by the levels of lactate dehydrogenase （LDH） in the coronary effluent. Ventricular hemodynamic parameters were also measured. Left ventricular myocardium was separated and cut into five slices. After experiment, the myocardium was used for evaluating myocardial infarct size with TTC stain. Immunohistochemical staining was used for observing phosphorylated Akt and GSK -3β expression. Results Ischemic postcondi tioning reduced LDH, CK release after reperfusion,improved the hemodynamic parameters and reduced myocardial infarct size（47.3 G vs 29.5%）. Phosphorylated Akt and GSK-3β expression increased markedly in group B. Wortmannin could reduce phosphorylated Akt expression. Phosphorylated GSK-3β expression increased in group D. Conclusion Ischemic postconditioning can protect myocardium against ischemia-reperfusion injury. Wortmannin, an Akt inhibitor, can weaken the eardioprotective effect of IPost, SB216763, a GSK-3β inhibitor, can simulate cardioprotection effect of IPost. Akt and GSK-3β play important roles in the mechanism of cardioprotetive signal pathway in IPost.