Stereospecific antiarrhythmic effect of opioid receptor antagonists in myocardial ischaemia

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Abstract
The effects of the stereoisomers of two different antagonists at opioid receptors were examined on the ventricular arrhythmias that result from acute coronary artery ligation in anaesthetized male rats. (−)−Mr 1452 (but not the (+)-isomer, Mr 1453) reduced, in a dose-dependent manner, the number of ventricular ectopic beats and the incidence or duration of both ventricular tachycardia and fibrillation. (−)−WIN 44,441–3 (but not its (+)-isomer, WIN 44,441–2) had a similar protective effect in ischaemia. These results suggest that antagonism of the effects of endogenous opioid peptides at specific receptors results in reduced severity of arrhythmias in myocardial ischaemia.