Arginine vasopressin excretion in response to volume expansion in the healthy human, and in patients with glomerulonephritis.

The urinary excretion of arginine vasopressin (AVP) was studied during volume expansion (VE) in nine healthy normotensive individuals and 14 patients with active IgA glomerulonephritis (GN). The studies were started after 17-18 h of food and fluid deprivation (hydropenia, HP) and VE was induced by a continuous infusion of Ringer solution up to an amount corresponding to 3% of the body weight. The clearance of inulin and PAH, urine osmolality and urinary excretion of sodium and AVP were determined. The AVP excretion decreased in response to VE in the healthy individuals, both when related to GFR (from 129 +/- 17 pg min-1 100 ml-1 GFR during HP to 65 +/- 9 after 3% VE, P less than 0.01) and to body surface area (BSA) (from 134 +/- 22 pg min-1 1.73 m-2 BSA to 75 +/- 11, P less than 0.05). In the patients with IgA GN, who had normal blood pressure and normal GFR, the AVP excretion tended to decrease, but the change was not significant (0.05 less than P less than 0.1). The patients with hypertension but essentially normal GFR, and those with hypertension and markedly decreased GFR did not change their renal excretion of AVP in response to VE. If related to the GFR, the latter patients had a markedly increased AVP excretion.