Inotropic Response of Cardiac Ventricular Myocytes to β-Adrenergic Stimulation With Isoproterenol Exhibits Diurnal Variation

Abstract

The threshold for the development of arrhythmic activity in response to isoproterenol is higher during the active period of the rat. We suggest this reflects a reduction in SR Ca(2+) loading and a diurnal variation in neuronal NO synthase signaling.