The goal of this proposal is to determine the nature of adenosine's role in myocardial glucose metabolism. The hypothesis to be tested is that adenosine stimulates glucose utilization during periods of decreased oxygen supply/demand ratio. The experiments proposed in this study are designed to 1) determine the effect of adenosine and adenosine receptor agonists on myocardial glucose metabolism in rabbit hearts at low and elevated workloads; 2) determine the effect of adenosine A1/A2 receptor antagonism on glucose metabolism of rabbit hearts at both low and elevated workloads; 3) determine the effect of adenosine on the subcellular distribution of the myocardial facilitative glucose transporters, GLUT4 and GLUT1; and 4) determine the effects of adenosine on glucose metabolism and GLUT4/GLUT1 transport distribution in isolated rabbit ventricular myocytes.