Effect of Systemic Ischemic Preconditioning on Myocardial Ischemia-reperfusion Injury

Objective To investigate whether transient systemic ischemia can precondition the heart against the ensuing myocardial ischemia-reperfusion injury.Methods 24 adult new zealand white rabbits of either sex were randomly divided into 3 groups,8 rabbits in each:ischemia-reperfusion group(group Ⅰ),classic IPC group(group IPC),and systemic ischemic preconditioning(group SIP).For group Ⅰ,the left anterio coronary(LAD) of each rabbit was occluded by suture silk for 30 min,followed by reperfusion for 120 min.For group IPC,5 min of LAD occlusion and 10 min of reperfusion were conducted twice,followed by the same procedures as were done in group Ⅰ.For group SIP,SIP was induced by rapidly(5 min)withdrawing blood from femoral artery to keep the mean artery pressure at 50 mm Hg for 10 min,and then the withdrawn blood was transfused back in 5 min,followed by the same procedures as in group Ⅰ.The index variance of serous troponin I(cTnI) concentration,superoxide dismutase(SOD) activity,malondialdehyde(MDA),NO level were measured respectively before ischemia,30 minutes after ischemia,30 min after reperfusion,and 120 min after reperfusion.Results(1)Before is chemia(pre-I),there was no statistical significane of all the index among the three groups(P0.05).(2)At the time of ischemia 30 min,reperfusion 30 min,reperfusion 120 min,the index of serous troponin I(cTnI) concentration and malondialdehyde(MDA) level in SIP and IPC group were obviously lower than that in group I(P0.05).Compared with group I,superoxide dismutase(SOD) activity and NO level were significantly higher in SIP and IPC group I(P0.05).(3)The protective effect in SIP group was more remarkable than that in IPC group,but there was no statistical significance between them of all the index(P0.05).Conclusion The systemic ischemic preconditioning(SIP) has an early protective effect on the myocardial ischemia-reperfusion injury and could decrease the cardiocyte necresis.