Kidney Glutaminase and Carbonic Anhydrase Activity and Tissue Electrolyte Composition in Potassium-Deficient Dogs

Abstract

K deficiency was induced in dogs by feeding a diet deficient in K and a diet deficient in both K and Cl, with and without desoxycorticosterone acetate (DCA) administration. A comparison was made of (a) the electrolyte compositions of plasma, skeletal muscle and kidney; (b) the glutaminase and carbonic anhydrase activities of the kidneys; and (c) the change of kidney enzyme activity and renal electrolyte excretion. Skeletal muscle K loss and Na gain occurred in dogs fed a low-K diet and administered DCA without any change in plasma Cl and HCO3 concentrations. Dogs given a diet low in both K and Cl and administered DCA exhibited a hypochloremia and an elevated plasma HCO3 content in association with a muscle K loss and Na gain. The kidney Na and K concentrations remained unaltered. It was concluded that the plasma Cl concentration is better maintained in dogs than in rats when K deficiency is induced in the presence of adequate Cl. Kidney glutaminase was increased in dogs given a low-K diet and tended to be reduced when the diet was restricted in both K and Cl. Changes of kidney glutaminase tended to parallel urinary ammonia excretion. Except with dogs fed the doubly deficient diet, kidney carbonic anhydrase was related to the urine total titratable acidity excretion. In the exception, carbonic anhydrase increased in the presence of a lowered total titratable acidity excretion. DCA administration tended to reduce kidney carbonic anhydrase activity.