Abstract
Summary: Red blood cell carbonic anhydrase activity was studied in three children with distal renal tubular acidosis, the parents of one of these patients, and in control subjects. Although each patient had distal renal tubular acidosis as defined by an inappropriately high urine pH in the face of a systemic metabolic acidosis, hyperchloremia and a low (U-B)pCO2, they differed in that two had deafness. The deafness was inherited as an autosomal recessive mode in one and by an autosomal dominant gene in the other.
Red blood cell carbonic anhydrase activity was determined in hemoglobin-free hemolysate by the esterolytic action of the enzyme on the substrate p-nitrophenyl acetate. The two isoenzymes, B and C, of carbonic anhydrase were identified using polyacrylamide disc gel electrophoresis. The red blood cell carbonic anhydrase activity of nine control children aged 2–10 years was 3.8 (3.2–5.0) units/g Hb. The values obtained from the three patients were 3.0, 3.7, and 4.36 units/g Hb. These did not differ from those of the control subjects. No abnormalities were found in the ratios of the B and C peaks or in their electrophoretic mobility.
Speculation: Although carbonic anhydrase appears to have an important role in the acidification of the urine, and although an abnormality in red blood cell carbonic anhydrase has been described in a patient with renal tubular acidosis and deafness, no abnormalities could be defined in red blood cell carbonic anhydrase activity in our three patients with renal tubular acidosis, two of whom were deaf.
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Kaplan, B., Mills, M., Hechtman, P. et al. Red Blood Cell Carbonic Anhydrase Activity in Children with Distal Renal Tubular Acidosis. Pediatr Res 11, 1039–1042 (1977). https://doi.org/10.1203/00006450-197710000-00002
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DOI: https://doi.org/10.1203/00006450-197710000-00002