Involvement of σ-Receptors in the Increase in Contraction of Mouse Vas Deferens Induced by Exogenous ATP

Abstract

Abstract The effects of σ-receptor ligands on the twitch contraction elicited by the exogenous application of adenosine 5′-triphosphate (ATP) in the unstimulated mouse vas deferens were studied. (-)-Pentazocine, 1,3−di(2−tolyl)guanidine (DTG) and two pairs of optical isomers of 3−(3−hydroxyphenyl)-N-(1−propyl)piperidine (3−PPP) and N-allylnormetazocine (SKF−10,047) potentiated the exogenous application of ATP-induced twitch-type contraction in a concentration-dependent manner, while (+)-pentazocine did not affect it. The order of potentiating ability was: (+)−3−PPP>(-)-pentazocine>(-)-SKF−10,047> DTG>(-)−3−PPP>(+)-SKF−10,047. On the other hand, haloperidol and rimcazole, putative σ-receptor antagonists, suppressed this twitch contraction. In addition, these antagonists significantly blocked the (+)-3−PPP- and (-)-pentazocine-induced potentiation at concentrations which did not affect contractions per se. These findings indicate that the exogenous application of ATP-induced twitch contraction in the mouse vas deferens is regulated by σ-receptors. In addition, the present ranking order suggests that the σ-receptor potentiating the ATP-induced twitch contraction at post-junctional sites may differ from the σ1- and/or σ2-receptor subtypes.