Vasopressin V2 Receptor Binding Is Down-Regulated during Renal Escape from Vasopressin-Induced Antidiuresis

This study evaluated whether renal escape from vasopressin-induced antidiuresis is associated with alterations of vasopressin V 2 receptor binding in the kidney inner medulla.A radioligand binding assay was developed using a novel iodinated vasopressin V 2 receptor antagonist to analyze vasopressin V 2 receptor binding in kidney inner medullary tissue from three groups of rats: normal rats maintained on ad libitum water intake, rats treated with 1-deamino-[8-D-arginine]vasopressin (DDAVP), and rats treated with DDAVP that were also water loaded to induce renal escape from antidiuresis.Analysis of the binding data showed that DDAVP treatment reduced vasopressin V 2 receptor binding to 72% of normal levels.Water loading