THE ACTION OF CERTAIN CHOLINE DERIVATIVES ON THE CORONARY FLOW

¹ From the Department of Physiology, University of Rochester, School of Medicine and Dentistry

The action on the coronary flow of acetylcholine, acetyl-beta-methylcholine, and carbaminoyl choline has been studied in the hearts of rabbits, cats, and dogs. Initial injections of each of these substances usually produced a prompt increase in coronary outflow which was followed by a decrease. In some hearts flow increase alone was seen, and in others only a decrease. Following repeated injections the responses were variable. The magnitude of flow change was usually much less and the constrictor action tended to predominate. The vasodilator effect appeared to be due to the muscarine component of the choline derivative and the constrictor action to the nicotine, as is the case for the systemic vessels.

On the heart muscle these compounds caused an immediate decrease in the amplitude of beat, which was soon followed by an increase. The muscle effects were not related either to change in rate or coronary flow.

Subcutaneous injections of acetyl-beta-methylcholine and carbaminoyl choline in the dog caused a decrease in coronary outflow which is thought to have been due largely to a constrictor action on those vessels. The possible bearing of some of the experimental observations on the therapeutic use of these drugs has been pointed out.

The experiments on dogs reported in this paper were done in the Department of Pathology of the University of Cambridge. I wish to acknowledge my indebtedness to Professor Dean for the opportunity of carrying out this part of the work and to Dr. Alan N. Drury for his kind assistance in performing those experiments.