The Role of NO Synthase, MPT pore, and Protein Kinase A in the Cardioprotective Effect of the Opioid Receptor Agonist Deltorphin II.

In male Wistar rats, coronary occlusion (45 min) and reperfusion (120 min) were modeled. Selective δ-opioid receptor agonist (deltorphin II, 0.12 mg/kg) was administered intravenously 5 min before reperfusion; NO synthase inhibitor (L-NAME, 10 mg/kg), MPT pore blocker (atractyloside, 5 mg/kg), and protein kinase A inhibitor (H-89, 10 μg/kg) were administered intravenously 10 min before reperfusion. Deltorphin II administered before reperfusion led to a 2-fold decrease in the infarct size. The infarct-limiting effect of deltorphin II was associated with blockade of MPT pore. Protein kinase A and NO synthase were not involved in the cardioprotective effect of deltorphin II.