Abstract: AIM: To study the influence of hawthorn leaves flavonoids on electrocardiogram (ECG), NO and malondialdehyde (MDA) of myocardial ischemia reperfusion injury in rats. METHODS: Myocardial ischemic reperfusion injury models were established by occluding the left anterior descending branch of coronary artery for 30 min and removing the ligation later to reperfuse for 60 min in vivo.Different dosages of hawthorn leaves flavonoids(12.5, 25.0, 50.0 mg/kg) were administered by i.p.10 min before the onset of ischemia.ECG was observed continuously and ST segments were measured.The concentrations of NO in blood serum were detected and the contents of MDA in myocardium were assaied in the same time. RESULTS: ST segments of ECG were relieved significantly treated with hawthorn leaves flavonoids (12.5, 25.0, 50.0 mg/kg).NO concentrations were increased and MDA contents were decreased significantly in the different dosages groups compared with control group. CONCLUSION: Hawthorn leaves flavonoids has protective effects on myocardial ischemia reperfusion injury.The effect were possibly attributed to increasing concentrations of NO and anti-lipid peroxidation.

Key words: hawthorn leaves flavonoids, myocardial ischemia reperfusion injury, electrocardiogram, nitrogen monoxidum, malondia1dehyde