Functional characterization of vasopressin V1 and V2 receptors in the rabbit renal cortical collecting duct

Recently we clarified the mechanism in which arginine-vasopressin (AVP) applied from the luminal side inhibits the basolateral Cl- conductance, which is stimulated by basolateral AVP. However, to prove that these vasopressin phenomena are expressed via receptor mediated actions, we examined the effect of specific V1 and V2 receptor antagonists, OPC-21268 and OPC-31260, respectively, on the electrical response to vasopressin in the rabbit CCD perfused in vitro. In the presence of the V2-antagonist, basolateral AVP caused only the activation of luminal Na+ conductance, indicating a V1 action. In the presence of the V1 antagonist, basolateral AVP caused the same biphasic responses in electrical parameters as cyclic AMP, representing a pure V2 action. On the other hand, a rise in cell Ca2+ in response to AW was completely abolished in the presence of the V1-antagonist, but not by the V2-antagonist in the bath. These data confirm our earlier findings that rabbit CCD possesses both V1 and V2 receptors in the basolateral membrane. We conclude that electrical responses to AVP in the rabbit CCD are a complex of V1 and V2 receptor-mediated actions.