The response of the kidney to an alkalosis during salt deficiency

Abstract

Alkalosis was induced by controlled over-breathing in 3 men and one woman, in normal health and when salt deficient. Tetany regularly accompanied the overbreathing and was not modified in any way by the cramps due to salt deficiency. Urine samples were taken immediately before and after the overbreathing periods. Overbreathing in normal subjects increased the minute volume of the urine, the pH, the rates of excretion of Na, K, chlorides, urea, caused no changes in the clearance of creatinine, Ca, Mg, sulphates or phosphates. The fixed base/fixed acid ratio increased. During salt deficiency, during overbreathing there was a generalized lowering of functional renal activity, accompanied by decreases in the minute volume, the rates of clearance of urea, creatinine, Na, K, Ca, Mg, sulphates and phosphates. The pH and the fixed base/fixed acid ratio remained practically unchanged, though the latter sometimes increased slightly due to decreased excretion of sulphates and phosphates. This renal deficiency cannot be attributed to the muscular exercise of overbreathing, since if CO2 is administered to prevent alkalosis there were no striking changes in the urine. There may be no shift to an alkaline pH in the salt deficient subject because of abnormal production of organic acids during overbreathing, or because there is so little Na available for excretion that differences in its clearance rate cannot appreciably affect the pH.