Abstract: The present study was carried out using 22 anesthetized dogs with reversible ligation of the left anterior descending coronary artery to determine the effects of infused puerarin on collateral blood flow to the ischemic myocardium and on systemic hemodynamics.Intravenous infusion of puerarin(10 mg/kg/min)during acute regional myocardial ischemia was associated with a decrease in heart rate from 174±6 to 149±6 beats/rain (P<0.001) and in mean arterial pressure from 105±9 to 80±8 mmHg (P<0.01). Despite the decrease in mean arterial pressure, collateral coronary blood flow (radiolabelled microspheres) did not decrease.In six right heart bypass experiments in which the hemodynamics were controlled, infusion of puerarin significantly lowered the tension time index and LV dP/ dt. Restoration of systemic blood pressure to the same level that existed prior to the infusion resulted in a substantial increase in collateral flow to ischemic myocardium from 0.55±0.12 to 1.36±0.39 ml/min/g (P<0.05) and in increase in coronary blood flow to nonischemic myocardium from 1.11±0.15 to 4.28±1.01 ml/min/g (P<0.05). The diminution of coronary vascular resistance was approximately twice that of systemic arterial resistance (P<0.025). The stroke work-left ventricular end-diastolic pressure relationship did not change significantly indicating that the infusion of puerarin did not affect myocardial contractility.The results suggest that puerarin lowers resistance to collateral blood flow to regional myocardial ischemia and diminishes the correlates of myocardial oxygen demand both of which would be expected to have a beneficial effect on ischemic rnyocardium. The data support the clinical potential of this agent.