ROLE OF THE VAGUS IN CONTROL OF THE MAJOR CONDUIT CORONARY-ARTERY IN THE DOG

Abstract

Using E1 Badawi and Schenk''s modification of Karnovsky''s method for the demonstration of acetylcholinesterase, cholinergic fibers were found in the perivascular connective tissue and directly in the wall (in the adventitia) of the major coronary arteries; the fibers were distributed regularly aroung the circumference of the arteries. In the smaller intramyocardial arteries the present in the wall of the veins. The shape and topography of the coronary cholinergic arterial plexus resembled the shape and topography of the coronary sympathetic adrenergic system. Stimulation of the cervical vagus did not affect the diameter of the large coronary arteries. Since acetylcholine (6-10 .mu.g/kg i.v.) produced a mean 7.4% increase in the diameter of the ramus interventricularis ventralis, there must be no postganglionic cholinergic fibers of vasomotor significance for the large coronary arteries in the cervical vagus. The specific acetylcholinesterase activity in the wall of these vessels belongs to cholinergic terminals whose ganglionic cells are not located in the vagal ganglion or to cholinergic axons terminating outside the wall of the large coronary arteries.