STUDIES ON THE MECHANISM OF BICARBONATE REABSORPTION IN MAN

Journal/Book: Reprinted from: THE JOURNAL OF LABORATORY AND CLINICAL MEDICINE St. Louis Vol. 56 No. 2 Pages 294-302 August 1960. 1960;

Abstract: From the Medical Radioisotope and Pathology Services Veterens Administration Hospital and the University of Minnesota Medical School The acute intravenous effects of acetazolamide an renal bicarbonate reabsorption in doses ranging from 67 to 120 mg. per kilogram body weight were studied in 7 men. Renal reabsorption of sodium potassium chloride and inorganic phosphorus was also studied. Sodium and chloride reabsorption decreased by approximately 8 and 4 per cent respectively. Reabsorption of bicarbonate and phosphate was inhibited by 40 and 26 per cent respectively. The decrease in phosphate reabsorption was independent of the decrease in glomerular filtration rate (GFR). Two subjects received intravenous infusions of sodium bicarbonate in amounts calculated to give alkali loads similar to that which could be expected from sodium acetazolamide. After bicarbonate Infusion excretion in excess of control was 5 to 10 per cent of that infused; in those subjects who received acetazolamide bicarbonate excretion in excess of control varied from 88 to 193 per cent of the administered alkali. This demonstrates that the alkalinizing effect of sodium acetazolamide could not have accounted for more than 10 per cent of excreted bicarbonate. The results are consistent with the concept that the major portion of bicarbonate reabsorption is dependent upon ion exchange. However the data also suggest an alternate pathway which is shared with inorganic phosphorus. . .

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