Adenosine blockade during reperfusion reverses the infarct limiting effect in preconditioned canine hearts

Abstract

Objectives: The aim was to investigate whether adenosine release after reperfusion contributes to infarct limitation by ischaemic preconditioning. Methods: Dogs underwent preconditioning with four 5 min cycles of left anterior descending coronary artery (LAD) occlusion and reperfusion, followed by 90 min LAD occlusion and 5 h reperfusion with or without the non-specific adenosine receptor blocker, 8-phenyltheophylline (8-PT). Infarct size was assessed by a dual staining method with triphenyltetrazolium chloride and Evans blue. Blood flow measurements in the subendocardial region were made by infusion of coloured microspheres before occlusion and midway through the sustained occlusion. Transcardiac alteration of neutrophillic function was assessed by luminol-enhanced whole blood chemiluminescence induced by zymosan. Results: Infarct size was significantly reduced in the preconditioned dogs [12.5(SEM 4.0)%, n= 10, pConclusions: An adenosine receptor blocker caused a moderate but significant reversal of infarct limitation by ischaemic preconditioning associated with a significant increase of neutrophillic function in the coronary circulation during early reperfusion. Cardiovascular Research 1994;28:1083-1088