Renal activity of vasopressin in anesthetized dogs.

Abstract

Conventional clearance techniques were used to study the renal response to vasopressin (5–100 mu/hr.) infused for 2 1/2 hours into anesthetized (pentobarbital), surgically traumatized dogs elaborating a dilute urine. Decreased urine flow, a concomitant sustained increase in Na+ excretion, increased urine osmolality, negative free-water clearance and an increased osmolal U/P ratio (>1, <2) consistently occurred during the infusion of 50 mu/hr. Urinary pH rose and HCO3–, rather than Cl–, was the predominant anion excreted. Tubular rejection of HCO3–, however, is not essential for vasopressin activity under the conditions of this investigation since antidiuresis occurred in an acidotic dog. Usually some increase in glomerular filtration rate and effective renal plasma flow were apparent during vasopressin infusion; the former change could account for the increased Na+ excretion, but it is difficult to ascribe the peculiar anion behavior to this factor. Maximum urinary concentration was not attained even with 100 mu vasopressin/hr.