Effects of postconditioning on the expression of heat shock protein 70 in rats with myocardial ischemia reperfusion

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(P0.05).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(P0.05).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.