glutaminase and Kidney-Calculi

Ammonia is quantitatively the major buffer for hydrogen ion in the urine. Further, the excretion of ammonia can be varied by acid base status and is therefore of homeostatic importance. Acid base status exerts its effect on ammonia excretion both directly and also via an effect on renal ammonia production from glutamine. The mechanism of the effect of acid base status on glutamine deamidation and deamination is uncertain. Apart from its homeostatic role in health and disease alterations in renal ammonia production may assume pathological importance in potassium depletion and uric acid urolithiasis.

Topics: Acid-Base Equilibrium; Acidosis; Ammonia; Animals; Dogs; Glutaminase; Glutamine; Humans; Hydrogen-Ion Concentration; Kidney; Kidney Calculi; Potassium Deficiency; Rats; Uric Acid

In four persons of one family the existence of an enzymatic defect, presumably consisting of a deficiency of glutaminase in the cells of the renal tubules, is postulated, and is implied by a reduced elimination of ammonia in the urine, by a relatively low urinary pH, and by its increased titratable acidity. The most characteristic clinical symptom is irritation of the distal part of the urinary tract, connected with numerous crystals of uric acid appearing in the urinary sediment. The elimination of uric acid is normal, or even reduced, and the level of uric acid in the blood serum is also within normal limits. After the administration of glutaminic acid elimination of ammonia is further decreased and the quantity of uric acid crystals is increased. Loading with glutaminic acid may also cause an attack of renal pain in the individual suffering from this defect but the administration of ammonium chloride does not cause any increase in ammonia production. It seems probable that the enzymatic defect is connected with the presence of antigen B in the erythrocytes and that it is inherited as a dominant autosomal feature. A suitable diet to make the urine alkaline allows kidneys to function efficiently in individuals suffering from this defect.

Topics: Erythrocytes; Glutaminase; Humans; Kidney; Kidney Calculi; Kidney Tubules; Metabolism, Inborn Errors; Uric Acid