XVI. THE EFFECT OF ADRENALIN UPON THE CORONARY CIRCULATION

Abstract

The literature on the effect of adrenalin and of vagus and sympathetic stimulation upon the coronary vessels is reviewed. Excised active and inactive hearts of cats, rabbits and rats were perfused with Locke''s solutions with pH''s of 6.2, 7, 7.4, 7.6, and 8.2 to which autogenous defibrinated blood to 2% was usually added. The alkaloid and synthetic adrenalin solution, adrenalin chloride and chloretone solutions in varying strengths were injected directly into the perfusate. Adrenalin (alkaloid and synthetic) in dilute solutions caused vaso-dilatation of the coronary vessels in both active and inactive hearts and concentrated solutions of the same preparations caused vaso-constriction of these vessels in cats, rabbits and rats. Adrenalin chloride and suprarenalin produced vaso-dilatation of the coronary vessels in all dilutions due to their increased acidity. The chloretone present in the adrenaline chloride solution is an added factor in its vasodilator action upon coronary vessels. Calcium increased the tonus of the coronary vessels, whereas potassium decreased it. It is concluded that the sympathetic nervous system supplies both vaso-dilator and vaso-constrictor fibers to the coronary circulation of the heart.