Characterization of rodent liver and kidney AVP receptors: pharmacologic evidence for species differences

Radioligand binding studies with [H-3]vasopressin (AVP) were used to determ ine the affinities of AVP receptor agonists and antagonists for mouse liver and kidney plasma membrane preparations. Both membrane preparations exhibi ted one class of high-affinity binding site. AVP ligand binding inhibition studies confirmed that mouse liver binding sites belong to the V-1A subtype while kidney binding sites belong to the V-2 receptor subtype. The affinit y of each ligand for mouse V-1A receptors was very similar to that for rat V-1A receptors, showing differences in K-i values of less than 3-fold. In c ontrast, several peptide (d(CH2)(5)Tyr(Me)AVP) and nonpeptide (OPC-21268 an d SR 49059) ligands had different affinities for mouse and rat kidney V-2 r eceptors, with differences in K-i values ranging from 14- to 17-fold. These results indicate that mouse and rat kidney V-2 receptors show significant pharmacologic differences. (C) 1999 Elsevier Science B.V. All rights reserv ed.