Action of beta-adrenoceptor blocking agents on hemodynamic variables and on baroreceptor and postganglionic sympathetic activities in rabbits.

Fifty-six experiments were performed in rabbits anesthetized by urethane or sodium pentobarbital. Baroreceptor (aortic nerve) and post-ganglionic sympathetic (renal nerve) activities were recorded, and peripheral resistances were determined after infusion of beta-adrenoceptor blocking agents (propranolol, pindolol, timolol). A progressive vasodilation was observed after the onset of infusion of the 3 drugs; at the same time arterial pressure decreased, but aortic flow did not vary significantly. Baroreceptor activity was enhanced, whereas efferent renal nerve activity was decreased.