Phosphorylation and deamination of adenosine by the isolated, perfused rat heart

Abstract

1. 1. Adenosine (initial concentration 0.5 mM) disappears from the perfusion medium of an isolated, beating rat heart at a rate of 1.4 ωmoles/min per g myocardial protein. About 75% of the adenosine converted is recovered as inosine. 2. 2. Evidence is presented that the inosine is formed from exogenous adenosine (initial concentration 5 or 500 ωM), without appreciable participation of the nucleotide pool. 3. 3. The isolated rat heart incorporates about 1.1 ωmoles [ 14C]adenosine per g myocardial protein into adenine nucleotides in a 30-min perfusion experiment. 4. 4. When the heart is perfused with about 5 ωM adenosine only a few percent is phosphorylated, whereas some 45% is deaminated. 5. 5. It is concluded that deamination of adenosine is by far the most important pathway of adenosine metabolism in the isolated, perfused rat heart, under the conditions employed.