Alterations Of MMPs/TIMPs In Rat Myocardium During Ischemia-reperfusion

Objective: To investigate alterations of expression of MMP-2, -9,TIMP-1, -2and the balance of MMPs/TIMPs in rat myocardium during myocardialischemia-reperfusion(I/R). To observe changes of MMP-2, -9,TIMP-1, -2 inreperfusion injury following myocardium ischemia with the pretreatment ofPravastatin and Valsartan. Then, to determine the protection for myocardialischemia-reperfusion Injury by modulating the MMPs/TIMPs balance withPravastatin and Valsartan.Methods: A rat model of myocardial ischemia-reperfusion was successfullyestablished. 30 minutes of ischaemia was followed by reperfusion for 0min, 1min,5min, 10min, 30min, 1h or 2h, and the rats sham-operated were served as controls.Myocardium suffered from ischemia-reperfusion injury and serum was used. Therelative expression of MMP-2, -9,TIMP-1, -2 mRNA and protein were determined byRT-PCR and immunohistochemistry, respectively. Activities of MMP-2,-9 in ratsserum were detected by zymography. In addition, changes of MMP-2, -9,TIMP-1,-2 were observed in rats with pretreatment of Pravastatin and Valsartan prior tomyocardial ischemia for 30min and 2h reperfusion by the same methods.Results: The expression of MMP-2,-9 mRNA tended to increase duringischemia reperfusion. There was significant difference of MMP-2 mRNA expressionin R_1h and R_2h compared with Sham and I_30min, respectively. but there was nodifference of MMP-9 mRNA expression in the whole I/R process. The expression ofTIMP-1,-2 mRNA were presented to decrease. The ratio of MMP-2/TIMP-2 andMMP-9/TIMP-1 were increased. The balance of MMPs/TIMPs tended to be impaired.The expression of MMP-2, -9 protein had a trend of increase; The expression ofMMP-2 protein was increased obviously at 30min of reperfusion, peaked at 2h ofreperfusion. From 1h of reperfusion, there was a marked increase in expression ofMMP-9 protein. From the beginning of reperfusion, the expression of TIMP-1 proteinwas presented significant decrease, and that of TIMP-2 protein was decreasedobviously at the beginning of R5min. MMPs/TIMPs tended to unbalance gradually.The activity of MMP-2 began to increase at 1min of reperfusion, peaked at 5min andgradually decreased to the level of group sham after 1h of reperfusion. The activity ofMMP-9 tended to increase. There was marked difference in R2h compared with sham.The expression of MMP-2, -9 and the activity of MMP-9 was decreased obviously ingroup pretreated with Pravastatin and group pretreated with Valsartan compared withgroup R2h, but there was no difference of the activity of MMP-2 in these two groupscompared with group R2h. The expression of TIMP-1, -2 mRNA and protein wereupregulated significantly after pretreatment with Pravastatin and Valsartan. Conclusions: During myocardial ischemia-reperfusion, the mRNA and proteinexpressions and the activities of MMPs were increased significantly, the mRNA andprotein expressions of TIMPs were downregulated dramatically, the balance ofMMPs/TIMPs tended to be impaired. But the ratio of MMPs/TIMPs was regulated tobalance after pretreatment with Pravastatin and Valsartan. We can conclude thatinhibition of the expression of MMPs mRNA and protein and upregulation of TIMPs,keeping balance of MMPs/TIMPs, may therefore be a potential target of treatment ofmyocardial reperfusion injury.