RESUMO
We performed a comparative analysis of infarction-limiting activity of analogues of opioid receptor agonist U-50488 under conditions of heart reperfusion in rats. Derivatives of amide N-methyl-2-(pyrrolidin-1-yl)cyclohexyl-1-amine were administered 5 min before reperfusion in a dose of 1 mg/kg, derivative II (opicor) was additionally used in a dose of 2 mg/kg. In a dose of 1 mg/kg, all derivatives of opioid U-50488 were ineffective and produced no infarction-limiting effect. Opicor in a dose of 2 mg/kg reduced the infarction size/area at risk ratio and improved the contractility parameters of the isolated heart. Opioid receptor antagonist naltrexone (5 mg/kg) abolished the infarction-limiting effect of opicor. Hence, the infarction-reducing effect of opicor is associated with activation of opioid receptors. We also demonstrated that the opioid (opicor) can improve cardiac contractility during the reperfusion period.