MOVEMENT OF 14C-UREA IN MICROPERFUSED HENLE’S LOOP OF ADRENALECTOMIZED RAT KIDNEY
Henle's loops of normal and adrenalectomized rats under nondiuretic condition were perfused with isotonic saline containing 3H-methoxyinulin and 14C-urea, and distal fluid was subsequently collected by micropuncture. Osmolality and radioactivities of tubular fluid, and concentrations of sodium, potassium, urea and inulin and osmolalities of urine and plasma were determined. In the adrex rats, the distal tubular fluid to plasma ratio of osmolality was elevated and the distal fractional recovery of 14C-urea was significantly increased, but the water reabsorption did not change. The distal recovery of 14C-urea in the control rats was not correlative to urinary osmolality. These results suggest that the increase in distal fractional recovery of the tracer in adrex rats is possibly produced by the lowered permeability of Henle's loop to urea but not by the decreased solvent drag.