AN EXPERIMENTAL ANALYSIS, BY MEANS OF ACETYLCHOLINE HYPOTENSION, OF THE PROBLEM OF VAGAL CARDIO-ACCELERATOR FIBERS

Abstract

A fall of blood pressure induced by acetylcholine results in acceleration of the normal dog''s heart. Removal of the sympathetic nerve supply of the heart and demedullation of the adrenals does not prevent this response. Reflex depression of vagal cardio-inhibitory tone and reflexly liberated sympathin do not account entirely for the acceleration which develops as a result of reduced arterial blood pressure in the dog whose adrenals are demedullated and whose cardiac sympathetic nerves have been cut. Reflex activation of cardio-accelerator fibers in both vagus nerves readily accounts for the acceleration.