Evidence for pharmacological similarity between α₂,‐adrenoceptors in the vas deferens and central nervous system of the rat

Abstract

Seven α 2 ‐adrenoceptor antagonists with diverse chemical structures have been examined for their effects at α 2 ‐adrenoceptors in the vas deferens and central nervous system of the rat. Antagonist potency assessed against the presynaptic α 2 ‐adrenoceptor agonist action of clonidine in the isolated vas deferens (RX 781094 > AWy 26703 > yohimbine > rauwolscine > piperoxan > mianserin > RS 21361) was highly correlated with the ability of these drugs to displace saturable [ 3 H]‐RX 781094 binding from cerebral cortex membranes. Similarly, antagonist potency in the vas deferens was highly correlated with antagonist activity in reversing the centrally‐mediated mydriasis induced by the selective α 2 ‐adrenoceptor agonist, guanoxabenz, in pentobarbitone‐anaesthetized rats. The results indicate that the presynaptic α 2 ‐adrenoceptors in the vas deferens are pharmacologically similar to characterized these α 2 ‐adrenoceptors in the central nervous system of the rat.