Abstract

The effects of anthopleurin-A (AP-A), a selective cardiotonic drug, on cardiac dynamics in intact, awake animals were examined. Dogs were instrumented in order to record left ventricular pressure, the derivative of left ventricular pressure (dP/dt), arterial pressure left ventricular end-systolic and end-diastolic diameters, cardiac output, left atrial pressure and heart rate. Left ventricular pressure, dP/dt, stroke volume and cardiac output were significantly increased (16, 46, 37 and 23%, respectively) by AP-A. AP-A significantly diminished heart rate 9 beats/min and left ventricular end-systolic diameter 1.9 mm. Mean arterial pressure, mean left atrial pressure and left ventricular end-diastolic diameter were unaltered by AP-A. Autonomic blockade with atropine and propranolol did not alter these responses on the myocardium qualitatively. Thus, it appears that AP-A has a direct positive inotropic effect on the myocardium in conscious animals with little or no effect on the peripheral circulation.