Fig. 6. Infarct size in in vitro rat hearts. Rats were subjected to 30 min of regional ischemia followed by 2 h of reperfusion. Postconditioning (Post-C) and morphine (Mor, 1 μm) reduced infarct size. The infarct-sparing effect of morphine was reversed by both N -nitro-l-arginine methylester (l-NAME, 20 μm) and 1H-[1,2,4] oxadiazolo [4,3-a] quinoxalin-1-one (ODQ, 10 μm). * P < 0.05 versus control. # P < 0.05 versus morphine. Reprinted with permission from Jang Y et al. , Anesthesiology 2008; 108:243–50.