Effects Of Puerarin Postconditioning On Myocardial Ischemia-reperfusion Injury In Rat Hearts

Objective: In this study, we mostly investigated the changes of several injury indexes and NF-kBp65,p50 protein content and MMP-2/TIMP-2 mRNA expression during ischemic reperfusion in rat heart,so as to initially research the therapeutic effects and protection mechanism of puerarin postcondition,comparing of ischemic postcondition. Consequently,we can provide new evidence for clinic application of puerarin and therapy of myocardial ischemic reperfusion.Methods: Rat models of myocardial ischemia-reperfusion injury were established. 50 healthy SD rats were randomly divided into 5 groups (n=10):①Sham: sham-operation group ;②I: 30 minutes of ischemia without reperfusion;③I/R:30 minutes of ischemia was followed by reperfusion for 30 minutes;④I-postC:ischemic postconditioning group;⑤Pur:puerarin postconditioning group. The severity of myocardial injury was evaluated by histopathologic signs, content of CK-MB and LDH in blood serum. The level of MMP-2 and TIMP-2 mRNA in myocardium was analyzed by RT-PCR, and content of NF-kB p65 and p50 protein by Western Blotting.Result: 1.Compared with sham-operation group and 30min of ischemic group, ischemic-reperfusion induced obviously increasing in concent of CK-MB and LDH in blood serum and changing of histopathologic signs. The protein contein of NF-kB p65 and p50 were significantly increased 30 minutes of reperfusion after 30 minutes ischemic(P〈0.05),as well as obviously increasing of MMP-2 mRNA level and the ratio of MMP-2/TIMP-2 and decreasing of TIMP-2 mRNA level(P〈0.05);2.conversly,after ischemic postconditioning and puerarin postconditioning ,in the same time point we observed that The protein expression of NF-kB p65 and p50 was marked inhibited(P〈0.05)and the MMP-2 mRNA level and the ratio of MMP-2/TIMP-2 ,as well as concent of CK-MB and LDH in blood serum were down(P〈0.05),and myocardial damage was also improved ,but above of all indexs there was no statistic differences between ischemic postconditioning and puerarin postconditioning groups(P>0.05).Conclusions:1. During the earlier period reperfusion(here is 30 minute),ischemic-reperfusion induced severe myocardial damage;The level of NF-kB p65 and p50 protein and MMP-2 mRNA expression were significantly increased ,but TIMP-2 mRNA level was markly decreased and the ratio of MMP-2/TIMP-2 became imbalanced , which suggested nuclear factor-kappa B, MMP-2 and the imbalance of MMP-2/TIMP-2 were involved in the progress of myocardial ischemic reperfusion injury;2. Being similar to ischemic postcondition,puerarin postconditioning obviously decreased myocardial cell injury and the level of NF-kB p65 and p50 protein and MMP-2 mRNA expression and the ratio of MMP-2/TIMP-2, which suggested puerarin postconditioning may contribute to myocardial protection by inhibiting the expression of nuclear factor-kappa B and MMP-2 and regulating the balance of MMP-2/TIMP-2 during ischemic reperfusion.