Inhibitory Effect of Doxycycline on MMP2/9 and its Improvement in Cardiac Function and Left Ventricular Remodeling After Myocardial Infarction in Rats

The objective of this research was to investigate the inhibitory effect of doxycycline (DOX) on MMP2/9 and the improvement in cardiac function and left ventricular remodeling (LVR) after myocardial infarction (MI) in rats.For this purpose, thirty-six rats were randomly divided into control (group A), model (group B) and experimental (group C) groups.A MI model was established in groups B and C by ligation of the left anterior descending (LAD) of the coronary artery, while the rats in group A underwent thoracotomy without ligation only.The rats in groups A and B were injected with normal saline, and the rats in group C were injected with DOX.Two weeks after the operation, the cardiac function of the rats was evaluated by color Doppler ultrasound, myocardial infarct size by Masson staining, collagen content and the ratio of type /III collagen by immunohistochemistry and immunoblotting respectively and activities of MMP2/9 by gelatin enzyme method.The results revealed DOX to cause reduction in the degree of ventricular enlargement and cardiac wall thinning, reduce the collagen content, increase the ratio of type /III collagen, decrease the activities of MMP2/9, and reduce myocardial destruction and remodeling in rats after MI.However, further clinical research is recommended for the evaluation of the effectiveness of DOX.