ACIDIFICATION OF THE URINE AND INCREASED AMMONIUM EXCRETION WITHOUT CHANGE IN ACID-BASE EQUILIBRIUM: SODIUM REABSORPTION AS A STIMULUS TO THE ACIDIFYING PROCESS 12

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Abstract
An alkaline infusion of Na2SO4 was given rapidly to a control group of subjects and to subjects previously stimulated to retain Na by Na free diets, adrenal steroids, or both. Although there were no significant changes in blood pH or CO2 content, the urine of the Na-retaining group became intensely acid, ammonium excretion increased, and there was a striking increase in the excretion of K. Despite an equivalent excretion of sulfate, the control group showed no consistent or significant change in urine pH or ammonium excretion and only a small increment in K excretion. It is concluded that a stimulus to reabsorb Na without equivalent amounts of anion will result in acidification of the urine and increased ammonium and K excretion. This response does not require any prior change in acidity of blood or tissues. The degree of urine acidity achieved is approximately proportional to the intensity of the stimulus to Na reabsorption.