CONTINUOUS ANTEGRADE WARM BLOOD CARDIOPLEGIA ATTENUATES AUGMENTED CORONARY ENDOTHELIUM-DEPENDENT CONTRACTION AFTER CARDIAC GLOBAL-ISCHEMIA AND REPERFUSION

Background: Experiments were designed to evaluate the effect of warm b lood cardioplegia on endothelium-dependent contraction of the coronary endothelium after cardiac global ischemia and reperfusion, Method: Do gs (It = 12 in each group) were exposed to extracorporeal circulation with the body temperature at 37 degrees C (group 1) or 28 degrees C (g roups 2 and 3), The ascending aorta was crossclamped for 120 minutes w hile continuous infusion of warm blood cardioplegec solution (group 1) or intermittent infusion of cold (4 degrees C) crystalloid cardiopleg ic solution (group 2) was pet-formed via the coronary arteries through the aortic root, Cardioplegic solution was not used in group 3 animal s, The heart was then allowed to function for 60 minutes of reperfusio n. Reperfused (groups 1, 2, and 3) and control (group 4) coronary arte ries were then harvested for study, Results: Perfusate hypoxia caused endothelium-dependent contraction in the arteries of all four groups t hat could be attenuated by N-G-monomethyl-L-arginine (L-NMMA) or L-NMM A plus D-arginine, but not by L-NMMA plus L-arginine or endothelin rec eptor A and B antagonist PD 145065, The endothelium-dependent contract ion results in groups 2 and 3 (75% +/- 4% and 80% +/- 5%, respectively ) were significantly greater than those in groups 1 and 4 (15% +/- 3% and 18% +/- 5%, respectively), Scanning electron microscope studies sh owed that platelet adhesion and aggregation, areas of microthrombi, di sruption of endothelial cells, smd separation of the intercellular jun ction could be found in coronary segments from groups 2 and 3, but not in vessels from groups 1 and 4, Conclusion: These experiments suggest that global ischemia and reperfusion enhances hypoxia-mediated endoth elium-dependent contraction of the coronary endothelium and damages th e ultrastructure. These kinds of changes can be prevented by continuou s antegrade infusion of warm blood cardioplegic solution during global ischemia.