EFFECT OF VASOPRESSIN V-1 (OPC-21268) AND V-2 (OPC-31260) ANTAGONISTSON RENAL HEMODYNAMICS AND EXCRETORY FUNCTION

Our objective was to assess the effect of endogenous AVP on renal hemo dynamics and excretory function. We measured mean arterial pressure (M AP), renal blood flow (RBF), glomerular filtration rate (GFR) and urin e osmolality before and after the intravenous infusion of a V-1 antago nist (OPC-21268), a V-2 antagonist (OPC-31260) and their vehicle (sali ne) in anesthetized male Wistar rats. The infusion of the V-2 antagoni st increased the urine flow rate and reduced the urine osmolality sign ificantly (p < 0.05). The infusion of saline and the V-1 antagonist di d not change the urine flow rate or the urine osmolality. The infusion of saline, the V-1 antagonist and the V-2 antagonist had no effect on MAP, RBF or GFR. These results suggest that endogenous AVP plays a cr itical role in the regulation of renal water reabsorption mediated thr ough the V-2 receptor.