The Effect of Reserpine on Phosphorylase Activity in the Isolated Rabbit Atria

Abstract

The increase in myocardial contractile force after administration of epinephrine is closely related to the activation of cyclic 3', 5'-AMP with a subsequent conversion of phosphorylase b to a (1-5). Further, it seems likely that there exists a close relationship between the level of circulating catecholamine and the activity of phosphorylase in the heart, based on the finding that the injection of ganglionic stimulating agents produces the simultaneous increase in myocardial contractile force and augmentation of phos phorylase activity (6). The observation of Nakatani (7) that physostigmine augments phosphorylase activity in the heart and this augmentation is prevented by prior reser pine is compatible with the view that endogenously liberated catecholamines increase phosphorylase a. However, there are controversial reports regarding the effect of reserpine on heart