The effect of adrenalin, ephedrine, and amphetamine on the tone of the coronary vessels and the oxygen absorption of the myocardium in the heart isolated by the langendorf principle

Summary

Experiments were carried out on cat hearts, isolated after Langendorf and perfused with Ringer-Locke solution. Cardiac oxygen uptake was determined by the difference in the oxygen content in the fluid flowing in and out of the heart, measured polarographically, as well as by estimating, the volume velocity of the coronary outflow. As established, adrenalin, ephedrine and amphetamine caused a marked rise of the cardiac oxygen uptake. The volume velocity of the fluid outflow from the coronary blood vessels increassed to a lesser degree than the cardiac oxygen uptake. Notwithstanding the rise of the oxygen uptake by the heart after use of adrenalin there was at times a reduction of the volume velocity of the coronary outflow. It is assumed that in using adrenalin there occurs a clash between two of its antagonistic effects on the coronary vessels: of an indirect one (due to the change of metabolism) — the vasodilating, and a direct one—the vasoconstricting. Usually dilation of the coronary vessels prevails, but sometimes there occurs a vasoconstricting reaction.

There is no precise conformity between the rise of frequency and strength of myocardial contractions, on the one hand, and the rise of the cardiac oxygen uptake under the effect of adrenalin, ephedrine and amphetamine, on the other hand.