Abstract: Objective To observe the effect of ischemic postconditioning on myocyte apoptosis in hyperlipemia rats with myocardial ischemic reperfusion.Methods Total forty-eight hyperlipemia SD rats were randomly divided into the sham-operation group, ischemic reperfusion group and ischemic postconditioning group with 16 rats in each group. The myocardial ischemic reperfusion model of rat was made. Rats in the ischemic reperfusion group were ligated for 40 min ischemia, and then reperfused for 240 min. Rats in the ischemic postconditioning group were treated for 40 min ischemia, reperfused for 10 s and 10 s ischemia for three cycles, and then reperfused for 240 min. Rats in the sham-operation group were opened the chest to braid for ringer without deligation. The presence of apoptotic myocytes was detected by the method of terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL). Meanwhile, the serum creatine kinase activity and myocardial infarct size were measured.Results The creatine kinase activity was 734.86±25.48 U/L in the ischemic postconditioning group and 967.64±28.16 U/L in the ischemic reperfusion group after reperfusion, all significantly higher than that (274.28±16.94 U/L) in the sham-operation group ( P<0.05), and it was significantly lower in the ischemic postconditioning group than that in the ischemic reperfusion group ( P<0.05). There was no significant difference in ratio of myocardial ischemic size and left ventricle after reperfusion between the ischemic postconditioning group and the ischemic reperfusion group. But the ratio of myocardial necrotic size and ischemic size of the ischemic postconditioning group was 24.8%±6.7% and significantly lower than that (38.2%±7.1%) of the ischemic reperfusion group ( P<0.05). No apoptotic myocardial cells were found after the reperfusion in the sham-operation group. The apoptotic rate in the ischemic postconditioning group (12.7%±2.8%) was significantly lower than that (20.9%±3.7%) in the ischemic reperfusion group ( P<0.05).Conclusion Ischemic postconditioning can relieve the ischemic reperfusion injury in hyperlipemia rats, the mechanism of which may be related with decreased myocardial apoptosis.

Key words: reperfusion injury, postconditioning, apoptosis