Abstract: Objective To establish and evaluate myocardial ischemia reperfusion injury of rats by using left coronary artery ligation. Methods The anesthetized rats of twenty-one were chest-opened. The left coronary artery was ligated with silk thread to produce ischemia of 45 minutes and was then relaxed to induce repeifusion of 180 minutes. The standard II lead of electrocardiogram was recorded. The mean arterial pressure and myocardial contractile function were measured. The average areas of myocardial ischemia/necrosis and survival rate of rats were calculated. Results The width and height of QRS wave were increased (P＜0.01) after ischemia and were then decreased (P＜0.01) significantly after reperfusion. The ST segment and T wave were up-shifted (P＜0.01) afler ischemia and were then lowered (P＜0.01) obviously after reperfusion. MAP, HR, LVSP, + dp/dtmax and -dp/dtmax were significantly reduced (P＜0.01) and LVEDP was remarkably increased (P＜0.01) afler ischemia. The tendency of the above indices after reperfusion was the same as that of ischemia. At 180 minutes, the average area ratio of ischemic zone/left ventricle and necrotic zone/ischemic zone were 34.3% and 49.6% respectively, and the survival rate of rats was 49.6%. Conclusions It was an available method to establish myocardial ischemia reperfusion injury model in rats by using left coronary artery ligation. The changes of electrocardiogram,MAP and myocardial contractile function,as well as myocardial ischemia/necrosis were obvious. The successful rate was achieved.

Key words: Myocardium, Ischemia reperfusion injury, Model