Experimental Study of Coronary Circulation by Coronary Artery Catheterization : (5) Direct Effects of Various Drugs on Coronary Circulation and Electrocardiographic Changes. Direct Effect of Nicotine and Ethyl Alcohol on Coronary Circulation and the Electrocardiographic Changes

Abstract

Nicotine has been believed to exert a vasoconstrictor action on the coronary vessels ; some investigators, however, recently claim a vaso-dilator action of the drug on the coronary vessels. No agreement has yet been reached on the action of ethyl alcohol as to whether it exerts a vaso-constrictor a vaso-dilator action on the coronary vessels. The author attempted to examine the action of both drugs on coronary circulation following the direct infusion of each drug into the left coronary artery through a coronary artery catheter in anesthetized, closed-chest dogs. Electrocardiographic changes were also studied.Method Using the same methods as in parts II, III and IV, the experiments were performed 12 times on 3 adult dogs. Leads CψD and CψS, representing right and left ventricular electrocardiogram respectively, were used in taking the serial electrocardiograms.Results(1) Nicotine(a) With 0.133 mg of nicotine coronary wedge pressure remained unchanged, and femoral arterial pressure rose slightly in the experiments with coronary artery perfusion from the dog's own femoral artery. With the same dose of the drug coronary blood flow increased in the experiments with coronary artery perfusion from a donor dog's femoral artery.(b) Infusion of 0.25 mg of nicotine caused a slight decrease in coronary blood flow with unchanged coronary wedge and femoral arterial pressures in the experiments with coronary artery perfusion from a donor dog's femoral artery.(c) Infusion of 0.4 mg of nicotine caused a slight decrease in coronary blood flow and unchanged coronary wedge and femoral arterial pressures in the experiments with coronary artery perfusion from a donor dog's femoral artery.(d) With 0.67 mg of nicotine coronary blood flow increased slightly, coronary wedge pressure remained unchanged, and femoral arterial pressure rose slightly in the experiments with coronary artery perfusion from the dog's own femoral artery. With the same dose of the drug coronary blood flow increased slightly and coronary wedge pressure remained unchanged in the experiments with coronary artery perfusion from a donor dog's femoral artery.(e) Infusion of 1.0 mg of nicotine slightly increased coronary blood flow in the experiments with coronary artery perfusion from the dog's own femoral artery. Coronary wedge pressure remained unchanged and femoral arterial pressure rose slightly.(2) Ethyl alcohol(A) Experiments with coronary artery perfusion from the dog's own femoral artery.(a) Infusion of 1.7% ethyl alcohol caused a slight increase followed by a decrease in coronary blood flow. Coronary wedge and femoral arterial pressures remained unchanged.(b) With 3.3% ethyl alcohol coronary blood flow decreased while coronary wedge and femoral arterial pressures showed no change.(c) With 5.0% ethyl alcohol coronary blood flow decreased and coronary wedge and femoral arterial pressures remained unchanged.(B) Experiments with coronary artery perfusion form a donor dog's femoral artery.(a) With 0.67% ethyl alcohol coronary blood flow increased, while coronory wedge pressure fell and femoral arterial pressure remained unchanged.(b) With 1.7% ethyl alcohol coronary blood flow increased slightly, coronary wedge pressure fell, and femoral arterial pressure remained unchanged in some and rose in other.(c) With 3.3% ethyl alcohol coronary blood flow decreased, coronary wedge pressure fell, and femoral arterial pressure remained unchanged.Conclusions(1) Nicotine exerts no direct action on the coronary vessels.(2) A small dose of ethyl alcohol tends to exert a vaso-dilator action, while a large dose causes vaso-constrictor of the coronary vessels.(3) Nicotine causes hardly any change in the electrocardiogram.(4) The more ethyl alcohol is used, the more the electrocardiogram changes. The changes are mostly depression of the S-T segment and inversion of the T wave.