MMP9 and myocardial infarction: In summary, our results showed that, during 7 days after AMI, compared with the AMI rats, in the HL-AMI rats, the myocardial infarct size, the plasma activity of myocardial enzyme, and the degree of myocardial fibrosis all remained at the higher levels; meanwhile, the quantity of CEPCs, the expression and the plasma levels of VEGF, eNOS, NO, MMP-9 in myocardial tissue all decreased more significantly.