THE NATURE OF THE ACTION OF INTRAVENOUS ALDOSTERONE: EVIDENCE FOR A ROLE OF THE HORMONE IN URINARY DILUTION*

Abstract

The effect of 500 [mu]gm of d-aldosterone on renal excretion of electrolyte and water has been investigated in normal subjects during water diuresis. The hormone produced no significant changes in renal plasma flow or glo-merular filtration rate. After a latent period of about an hour a marked reduction in sodium and chloride excretion occurred which lasted for 2-4 hours. The hormone also increased K+ excretion, but this effect was temporally dissociated from the effect on NaCl output. Urine flow did not change or declined slightly, and the decrement in osmolar excretion approached or was equal to the increment in free water excretion produced by the hormone. The results indicate that aldosterone can promote net abstraction of sodium chloride without water from the urine of a distal portion of the renal tubule.