Fig. 3. Myocardial inducible nitric oxide synthase (iNOS) expression in wild-type or iNOS gene-knockout mice (iNOS-KO) pretreated with saline or morphine (M0.1 = 0.1 mg/kg; M0.3 = 0.3 mg/kg) 24 h before death. ( A ) Representative Western blot picture showing iNOS expression. ( B ) Densitometric quantification of iNOS expression (arbitrary units). * P < 0.05 versus saline group.