Defect in the Renal Tubular Reabsorption of Water Associated With Potassium Depletion in Rats

Abstract

The effect of graded degrees of K depletion on the ability to produce a concentrated urine was studied in Sprague-Dawley rats. With increasing degrees of K depletion, as measured by the concentration of K in fat-free skeletal muscle, there was a progrossive decrease in the maximum urinary concentration. This defect of the renal concentrating mechanism appeared to be better correlated with the degree than with the duration of potassium depletion and could be demonstrated either by the use of exogenous vasopressin or by water deprivation. The potassium-deficient rats in at least one experiment developed a significant polydipsia. The data do not allow any conclusions with respect to the relationship of the polydipsia to the renal concentrating defect except that the latter at least was not severe at the onset of the increased water intake.