ADENOSINE ANTAGONISM DECREASES METABOLIC BUT NOT FUNCTIONAL RECOVERY FROM ISCHEMIA

The effect of adenosine receptor antagonism on function and metabolism was examined in isolated hearts during low flow ischemia and reperfusion. Isovolumic rat hearts perfused at constant flow were subjected to 30 min of ischemia followed by 30 min of reperfusion. Infusion of vehicle or 10-mu-M 8-phenyl-theophylline (8-PT) was initiated 10 min before ischemia and maintained throughout reperfusion. 8-PT infusion had no significant effects on hemodynamic parameters or metabolism preischemia. During ischemia, left ventricular developed pressure declined to approximately 15% of preischemic values in control and 8-PT hearts, and ATP and PCr decreased to approximately 73 and 60% of preischemic values. Inorganic phosphate (P(i)) increased to 353 +/- 41 and 424 +/- 53% of preischemic values in control and 8-PT hearts, respectively. After reperfusion, function recovered to > 95% of preischemic levels in control and 8-PT hearts. Unlike control hearts, recovery of metabolites was significantly different during reperfusion in 8-PT hearts (P < 0.05); ATP, phosphocreatine, and P(i) recovered to 82 +/- 8, 71 +/- 8, and 281 +/- 27% of preischemic values, respectively. Venous purine washout was significantly greater (P < 0.05) during reperfusion in 8-PT hearts (327 +/- 113 nmol) than in control hearts (127 +/- 28 nmol). Blockade of adenosine receptors appears to be adversely affect metabolic but not functional recovery in the ischemic-reperfused myocardium.