Fig. 2. Area at risk (AAR) expressed as a percentage of the left ventricle (LV) and myocardial infarct size (IS) expressed as a percentage of AAR in all experimental groups. Saline: mice received saline 0.1 ml 24 h before coronary occlusion. M0.1 or M0.3: mice received 0.1 or 0.3 mg/kg morphine, respectively, 24 h before coronary occlusion. S -methylthiourea sulfate (SMT) was given 30 min before coronary occlusion. Inducible nitric oxide synthase gene-knockout mice (iNOS-KO) were pretreated with saline or morphine. * P < 0.05 versus saline group.