THE EFFECTS OF ADRENALIN ON THE REFLEX EXCITABILITY OF THE AUTONOMIC NERVOUS SYSTEM

Abstract

Narcotized cats with the cervical sympathetic supply severed on one side showed that inj. or secretion of adrenalin typically reduced not only the blood pressure responses to stimulation but also the reactions of the sympathetically innervated pupil, nictitating membrane and sweat glands of the foot pads. Sympathetic responses to stimulation within the hypothalamus were likewise reduced by adrenalin. The reflex inhibition of parasympathetic tonus in the sympathectomized pupil was increased, thus giving indication of inhibitory affects on both branches of the autonomic system. Discontinuation of adrenalin or ligation of both adrenals reversed these observations. These inhibitory effects were in general attributable to the operation of homeostatic mechanisms in compensation for the effects of adrenalin on peripheral mechanisms.