A STUDY OF TIME WINDOW FOR OXIDATIVE STRESS ASSOCIATED WITH MYOCARDIAL-ISCHEMIA AND REPERFUSION

Objective. To investigate the time window for oxidative stress occurre d in myocardial tissue and associated with reperfusion. Methods. Thirt y nine conscious rabbits were subjected to 0.5 hours (h) of myocardial ischemia and reperfusion for Oh, 6h, 24h and 72h, respectively, and n ine rabbits served as controls. Activities of superoxide dismutase (SO D), glutathione peroxidase (GSH-px) and myeloperoxidase (MPO), and con tents of GSH and malondyaldehyde (MDA) were measured in myocardial tis sues taken from ischemic non-necrotic area (INNA), ischemic necrotic a rea (INA) and non-ischemic area (NIA), respectively. Results. The anti oxidant status of INNA was weakened at 6th h, 24th h, and 48th h of re perfusion. Activities of Mn-SOD and Cu-Zu-SOD returned to normal value at 72nd h of reperfusion, but GSH-px activity and GSH content remaine d in lower value. MDA content had a marked increase at 6th h, 24th h, 48th/h and 72nd h of reperfusion. MPO activity had a progressive incre ase after reperfusion, with its peak value at 48th h, and PMN accumula tion occurred mostly in necrotic zone and its outer board zone. A mild oxidative stress also occurred in non-ischemic tissue, but without ob vious neutrophils infiltration. Conclusions. The time window for oxida tive stress associated with myocardial ischemia and reperfusion lasts for at least 72 h, and PMN infiltration is one of the most important f actors of delayed myocardial reperfusion injury.