Objective:To explore the effects and mechanisms of insulin postconditioning on myocardial protection in isolated rat hearts.Methods:32 Wistar rats were randomly divided intocontrol group

ischemia/reperfusion group(I/R group)

low dose insulin postconditioning group(L-POST group)and high dose insulin postconditioning group(H-POST group)

with 8 rats in each group.Langendorff and neely perfusion models were steadily established

then the rat hearts were arrested by cardioplegia(St.Thomas No.2 solution

STH-2)after perfusion for 30 min.These arrested hearts were remained for 30 min at 4℃and then underwent reperfusion for 60 min.In L-POST group and H-POST group

the arrested hearts were reperfused by Krebs-Henseleit buffer solution(K-H)with insulin.The content changes of myocardial eNOS and PKC were detected by immunohistochemistry and Western blo(tWB)

the AI(Apoptosis index

AI)of cardiomyocyte was detected by TUNEL.Results:Compared with control group

higher expression of eNOS and PKC and higher AI were detected in I/R group、L-POST group and H-POST group (P<0.05);compared with I/R group

higher expression of eNOS and PKC and lower AI were detected in L-POST group and H-POST group(P<0.05);compared with L-POST group

higher expression of eNOS and PKC

and lower xpression of AI were detected in H-POST group(P<0.05).Conclusion:The insulin postconditioning could protect heart from myocardial ischemia/reperfusion injury

which might be associated with increased eNOS

PKC

and inhibited apoptosis.The effect of high dose insulin postconditioning is better than that of the low dose.