缺血后处理对大鼠缺血/再灌注心肌热休克蛋白的影响

关键词：再灌注损伤  热休克蛋白  凋亡

Keywords:reperfusion injury  heat shock protein  apoptosis

摘要：

      目的:研究缺血后处理对大鼠缺血/再灌注心肌热休克蛋白(HSP70)的影响。方法:选择健康SD大鼠48只，随机分为3组：假手术组、缺血再灌注组（对照组）和缺血后处理组，每组16只。制备大鼠心肌缺血/再灌注模型。缺血再灌注组,收紧结扎线缺血40 min, 放松结扎线再灌注240min；缺血后处理组,缺血40 min后, 再灌注10s,缺血10s,连续3个循环，然后再灌注240min；假手术组，开胸后穿线做套环，但不收紧结扎线。免疫组织化学染色检测HSP70的表达，TUNEL 法检测心肌细胞凋亡指数，同时测定血清肌酸激酶活性。结果:①血清肌酸激酶活性测定：再灌注结束后缺血后处理组和缺血再灌注组肌酸激酶活性明显高于假手术组，分别为（712.13±42.77），（935.17±57.99），（282.74±29.54）U/L，P＜0.05，缺血后处理组明显低于对照组(P＜0.05)。②心肌凋亡细胞计数：再灌注结束后假手术组未见明显细胞凋亡（＜5%），缺血后处理组心肌细胞凋亡率明显低于缺血再灌注组，分别为（14.3±2.7）%，（22.3±3.6）%，（P＜0.05）。③心肌热休克蛋白表达：缺血后处理组较对照组心肌热休克蛋白表达增强（P＜0.05）。结论:缺血后处理可减轻缺血再灌注损伤，其机制可能与增强热休克蛋白表达，减少心肌细胞凋亡有关。

Abstract:

      Objective: To study the effects of postconditioning on the expression of heat shock protein(HSP) 70 in rats with myocardial ischemia reperfusion. Method: The rat′s myocardial ischemia model was established in anesthetized open-chest rat, the left anterior descending (LAD)coronary artery was occluded for 40 min and reperfused for 4h. The total of 48 rats were randomly divided into three groups: ischemia reperfusion control(R) group(n=16): no intervention at reperfusion; ischemic postconditioning(IP)group(n=16): after LAD occlusion, three cycles of 10s reperfusion followed by 10s LAD re-occlusion were applied during the first min of reperfusion; sham operation(S) group(n=16): the surgical procedure was identical to other groups, but the LAD ligature was not ligated. The expression of HSP70 was detected by immunohistochemistry. The presence of apoptotic myocytes was detected by the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling(TUNEL) method. Meanwhile, the serum creatine kinase activity was measured. Result:Serum creatine kinase activity in IP group was lower than that in control group（P<0.05). There was no significant apoptosis after reperfusion in sham-operation group, and the apoptotic rate in IP group was remarkably lower than that in ischemic reperfusion group. The amount of HSP70 in IP group was significant higher than that in control group and sham operation group(P<0.05). Conclusion:IP could alleviate reduce myocardial ischemia reperfusion injury significantly. The myocardial protection of postconditioning may be realized by up-regulating the expressions of HSP70 and decreasing myocardial apoptosis.