Effects of matrix metalloproteinase on ventricular remodeling after myocardial infarction in rats

Objective To characterize the time-course of matrix metalloproteinase (MMP-2,9) and endogenous tissue inhibitor of MMPs (TIMP-1) up-regulation during left ventricular remodeling following myocardial infarction in rats.Methods The descending left coronary artery of male rats (Sprague-Dawley) was ligated to produce a myocardial infarction model.Sixty-eight rats were randomly divided into control group (n=20) and myocardial infarction group (n=48).Protein was obtained on left ventricular samples containing scar and myocardium together.The activity of MMPs was measured by zymography and determined by Western-blotting.Results The activities of MMP-9 were not detected in normal rat heart.The activities and amount of MMP-2 in the myocardial infarction group were increased significantly at the 1st and 2nd week,and MMP-9 at the 1st,2nd and 4th week.On the contrary,TIMP-1 protein was decreased.Conclusion After myocardial infarction,MMP-2,9 protein was increased significantly,while TIMP-1 protein was decreased.These changes may be the major causes of ventricular remodeling.MMP-9 may be crucial in the process of ventricular remodeling.