Abstract: Objective To investigate the effects of coronary artery ligation precondition(CAIP) and femoral ligation precondition(FIP) on nitric oxide synthase in myocardial ischemic reperfusion injury and explore its impact on myocardial protection.Methods Myocardial ischemic/reperfusion model was produced by 60 min ischemic and 30 min reperfusion,observing the change of +LVdp/dtmax and-LVdp/dtmax of the cardiac dynamics,examining the activities of inducible nitric oxide synthase(iNOS) and constrictive nitric oxide synthase(cNOS)of myocardium.Results Compared with group I/R,dp/dtmax increased in group sham,CAIP+I/R and FIP+I/R(P<0.01).The activities of cNOS in group I/R were lower than those in group sham,CAIP,CAIP+I/R and FIP+I/R(P<0.01).Compared with group I/R,the activities of iNOS decreased in group sham,CAIP and CAIP+I/R(P<0.01).Conclusion Two precondition methods of CAIP and FIP resulted in a significant improvement of cardiac functional recovery of the ischemic-reperfusion heart in rats.The cardioprotection of CAIP is possibly related to the changes of cNOS and iNOS,and the cardioprotection of FIP is related to the activity of cNOS.

Key words: precondition, myocardium, ischemic-reperfusion injury, nitric-oxide synthase