缺血后处理对兔缺血再灌注心肌保护作用的信号转导机制研究

目的：建立缺血再灌注模型,观察JAK-STAT信号通路是否介导了缺血后处理对兔心肌的保护作用。方法：健康新西兰大白兔随机分为3组,（l）假手术组,开胸后穿线套环,不收紧结扎线。（2）I/R组,结扎冠状动脉左前降支（LAD）30min,再灌注180min。（3）缺血后处理组,结扎LAD 24 min时,用血管夹夹闭双侧股动脉5 min,松开1 min,再灌注直至180min;再灌注结束后伊文思蓝和TTC染色法测心梗面积,用原位化学法（TUNEL）法观察各组心肌细胞凋亡,免疫印迹法（WesternBlot）测各组心肌BCL-2及P-Stat3的表达。结果：（1）心梗面积：缺血后处理组（19.9±5.4%）较I/R组（29.9±4.6%）有明显减少（P〈0.05）,（2）各组心肌细胞凋亡的变化：I/R组、缺血后处理组的心肌细胞凋亡指数均较l组明显增加（P〈0.05）,（3）组的心肌细胞凋亡指数明显低于I/R组（P〈0.05）。（4）各组的心肌BCL-2蛋白表达变化：I/R组、缺血后处理组的心肌BCL-2的表达均较假手术组明显增加（P〈0.05）,缺血后处理组的心肌BCL-2的表达明显高于I/R组（P〈0.05）。（5）各组心肌P-Stat3蛋白表达：I/R组、缺血后处理组的心肌P-Stat3蛋白表达均较假手术组明显增加（P〈0.05）,缺血后处理组的心肌P-Stat3蛋白表达明显高于I/R组（P〈0.05）。结论：缺血后处理通过JAK-STAT信号通路的介导,上调BCL-2及P-Stat3蛋白的表达,抑制心肌细胞的凋亡,对缺血再灌注兔心肌产生保护作用。

THE SIGNAL MECHANISM OF THE PROTECTION OF ISCHEMIC POSTCONDITIONING ON MYOCARDIUM DURING ISCHEMIA/REPERFUSION IN RABBIT HEART

Objective：To investigate the signal mechanism of the protection of ischemic postconditioning on myocardium during ischemia/reperfusion in rabbit.Methods： All animals were randomly divided into three groups：（1）sham group;（2）I/R group,（3）I-PostC group.In group3,when the LAD was occlused for 24min,the femoral arteries were occlused for 5min,and then were unclamped for 1min,and reperfused to 180min All groups underwent 30min of coronary occlusion followed by 180min of reperfusion except Group1.At the end of the reperfusion,infarct size（IS）and area at risk（AAR） were defined by Evans and TTC staining.Cardiac myocyte apoptosis was defined by Terminal deoxynucleotidyl Transferase mediated dUPT nick-end labeling（TUNEL）method.The levels of BCL-2 and P-stat3 activity were determined by Westen Blot analysis.Results：Myocardial ischemic postconditioning and significantly（P〈0.05）reduced infarctsize（19.9±5.4%） compared with I/R group（29.9±4.6%）.In Group 2,ischemia/reperfusion caused significant cardiac myocyte apoptotic death.Ischemic postconditioning and morphine produced a significantly anti-apoptotic effect as evidenced by a marked reduction of apoptotic index in I/Rgroup.The activity of BCL-2 and P-stat3 in Group3 was higher than that of on Group2（P〈0.05）.Conclusions： Ischemic postconditioning can inhibit cardic myocyte apoptotic death,and promote the activity of BCL-2 and P-stat3 in myocardium during ischemia reperfusion,which is likely activitied by JAK-STAT signal pathway,and may be one of the molecular mechanisms of ischemic postconditioning on cardioProtection.