of Adenosine Release

Background We have previously reported that ischemic preconditioning increases 5'-nucleotidase activity and adeno-sine release during ischemia and reperfusion. However, its direct cause-and-effect relation has not been proven. To test the idea that the infarct size-limiting effect of ischemic pre-conditioning is blunted by inhibition of ectosolic 5'-nucleotid-ase activity, we assessed 5'-nucleotidase activity, adenosine release, and infarct size caused by sustained ischemia with and without an exposure to a,,3,-methylene adenosine 5-diphos-phate (AOPCP) in the ischemia-preconditioned myocardium. Methods and Results In 67 open-chest dogs, the left anterior descending coronary artery was cannulated and perfused with an extracorporeal bypass tube from the carotid artery. After hemodynamic stabilization, the coronary artery was occluded four times for 5 minutes separated by 5 minutes of reperfusio