Free radical biology & medicine
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Morphine treatment for 5 days protects heart against ischemia-reperfusion (IR) injury. This study evaluated the involvement of nitric oxide (NO) in morphine-induced renal protection. Three weeks after right nephrectomy, increasing doses of morphine were administered (20-30 mg kg(-1)day(-1), 5 days) to develop dependence in rats. ⋯ NO production was not decreased during the withdrawal period (p>0.1 vs morphine dependence+IR group). Morphine dependence provided renal protection in the acute phase and during withdrawal. Excessive increase or decrease in NO production abolished the effects of morphine, which suggested a role for balanced NO production and iNOS expression.