EXCRETION AND REABSORPTION OF SODIUM AND WATER IN THE ADRENALECTOMIZED DOG

Abstract

The rates of glomerular filtration of 5 well-hydrated adrenalectomized dogs were maintained within normal limits for periods up to 3 mos. following operation. These animals exhibited a reduced capacity to eliminate Na under high salt load, analogous to their reduced capacity to eliminate water under high water load. Reduction in Na and water excretion under the conditions of these expts. is therefore due to increased tubular reabsorption rather than to reduced glomerular filtration. The low volume and high salt concn. of the urine and the very considerable osmotic work performed by the kidney of the adrenalectomized animal under salt load suggest an overproduction of, decreased destruction of, or hypersensitivity to antidiuretic hormone. Such a view is consistent with the known susceptibility of the adrenalectomized animal to water intoxication. In the light of the natriuresis and chloruresis produced in the normal animal by relatively small quantities of pitressin, this view is consistent with the negative Na and chloride balances observed in untreated operated animals. Retention of K is a manifestation of specifically increased ionic reabsorption, and is not directly related to diminished Na absorption.