ACTION OF BETA-ADRENOCEPTOR BLOCKING-AGENTS ON HEMODYNAMIC VARIABLES AND ON BARORECEPTOR AND POSTGANGLIONIC SYMPATHETIC ACTIVITIES IN RABBITS

Google Scholar
  • 1 January 1978
    • journal article
    • research article
    • Vol. 28  (1) , 67-72
Abstract
Experiments (56) 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, but efferent renal nerve activity was decreased. A peripheral vasodilation produced by sodium nitroprusside did not induce an increase in baroreceptor activity; this enhanced activity is not likely the result of an increase in diameter of the aortic arch. A possibile modification in the sympathetic control of baroreceptor reflexogenic areas may be responsible for the enhanced baroreceptor activity. This phenomenon may contribute to the reduction in sympathetic outflow by the supraspinal negative feedback.