Metabolism of purine derivatives by the isolated cat heart

Abstract

Perfusion of the isolated cat heart with Tyrode's solution containing adenosine, adenosine-8-C14 or ATP induced an increase in coronary flow and in the amount of inosine and hypoxanthine in the perfusate compared to the results obtained by the perfusion of Tyrode's solution alone. Perfusion of the cat heart with inosine did not induce coronary vasodilation. Adenosine deaminase and nucleoside phosphorylase were leached out of the isolated cat heart preparation during the perfusion process. Adenosine, added to perfusate collected after one passage through the cat heart, was converted to inosine and hypoxanthine. When the heart was perfused with adenosine-8-C14 approximately 50% of the adenosine entered the myocardial cells where it was trapped as adenine nucleotide, whereas the remainder was recovered in the perfusate as inosine and hypoxanthine. Perfusion of dinitrophenol induced coronary vasodilation and an increase in the amount of inosine and hypoxanthine recovered in the perfusate. It is postulated that the dinitrophenol effects the release of adenosine from the myocardial cells and thereby produces coronary vasodilation.