EFFECT OF V2 ANTAGONIST ON CLEARANCE OF ARGININE VASOPRESSIN BY ISOLATED PERFUSED RAT KIDNEYS

Isolated rat kidneys were perfused with Krebs-Henseleit-bovine serum albumin solution at a mean pressure of 99 +/- 2.6 mmHg. After control periods, arginine vasopressin (AVP) was added to the perfusate at a final calculated concentration of 25 pg/ml (2.5 x 10(-11) M). Urine and perfusate samples were collected at 15-min intervals for the following 60 min to measure kidney function and the renal clearance of immunoreactive AVP (irAVP). At 15-30 min after the addition of AVP, total renal clearance of irAVP was 1,623 +/- 190-mu-l.min-1.g kidney wt-1. Glomerular filtration accounted for 35 +/- 3.0% of the total clearance, and 65 +/- 10.3% was cleared by peritubular pathways. Of the filtered irAVP, 48 +/- 4.8% was recovered in the urine. To investigate the importance of V2 receptors in the metabolism of AVP, clearance measurements were made in the presence of the V2 antagonist [d(CH2)5,D-Ile2,Ile4,Arg8]AVP (5 x 10(-9) M). Total renal clearance of irAVP was reduced by 48% to 848 +/- 79-mu-l.min-1.g-1. This reduction was entirely accounted for by the complete inhibition of peritubular clearance of irAVP. In the presence of the V2 antagonist, irAVP was cleared only by filtration. The proportion of filtered AVP recovered in the urine (53 +/- 8.7%) was not significantly altered by the presence of the V2 antagonist. We conclude that a major component of the renal clearance of AVP depends on receptor-mediated uptake of AVP in the kidney cells.