A comparison of the direct effects and adrenergic blocking activity of D/L- and D-propranolol on the electrical and mechanical behaviour of isolated frog ventricle.

Abstract

Propranolol was found to reduce the rate of depolarization, amplitude, and duration of the action potential recorded from frog ventricular myocardium. In these respects, D-propranolol was of similar potency to D/L-propranolol. However, D/L-propranolol was much more effective than the dextro isomer in blocking the increase in rate of depolarization, amplitude, and duration of the action potential caused by adrenaline; it was also much more potent than the dextro isomer in blocking the inotropic response to adrenaline.