Involvement of endogenous opioid receptor agonists in increasing cardiac resistance to the damaging effects of reperfusion

It was found that an intravenous administration of the nonselective of opioid receptor (OR) antagonists naltrexone (5 mg/kg) and also the selective antagonist δ1-OR BNTX (0.7 mg/kg), the selective δ2-OR blocker naltriben (0.3 mg/kg), the κ-selective antagonist nor-binaltorphimine (2 mg/kg), do not affect cardiac reperfusion injury in vivo. It is established that the μ-selective antagonist CTAP limits infarct size.