Fig. 5. Oxidant stress during reperfusion. (A ) Pretreatment with morphine decreased free radical production during reperfusion compared with controls (Cont). Attenuated oxidant stress with morphine was reversed by pretreatment with naloxone (Nalo+Mor) or 7-benzylidenenaltrexone (BNTX+Mor). Attenuated oxidant stress with BW373U86 was abolished by diethyldithiocarbamic acid (DDC+BW) or 5-hydroxydecanoate (5-HD+BW;B ). * P < 0.05. DCF = dichlorofluorescein; A.U. = arbitrary units.