Comparison of “selective” opiate receptor antagonists on the isolated mouse vas deferens

Abstract

The selectivity and relative potencics of opiate receptor antagonists were compared on the mouse vas deferens preparation. ICI-174864 was found to be a highly selective antagonist at delta opiate receptors equal in potency to naltrexone in blocking the actions of delta agonists. Although less potent than naltrexone, beta-funal trexamine (beta-FNA) and Mr-1452, like naltrexone, were less selective in that they blocked the actions of mu, delta and kappa agonists. The relative potencies of beta-FNA and Mr-1452 in antagonizing the three types of agonists also were similar to naltrexone.