The excretion of I-malic acid in relation to the tricarboxylic acid cycle in the kidney.

  • P VISHWAKARMA, W. D. Lotspeich
  • Published 1959 in The Journal of clinical investigation


* This work was supported by grants (A-1381) from the National Institutes of Health, United States Public Health Service, and the American Heart Association and the Youngstown Area Heart Association. t Research Fellow in Physiology, on leave from State Medical Service of Bihar, India. the excretion of some of these acids shows remarkable variations. For instance, in metabolic alkalosis the rate of excretion of citrate and to a lesser extent of a-ketoglutarate is greatly elevated (3-6). On the other hand, in metabolic acidosis, or more precisely in conditions favoring intracellular acidosis such as potassium deficiency (4, 5) or the administration of Diamox@ (7), the rate of excretion of these same acids is reduced almost to zero. The way in which fluctuating acid-base balance causes these changes in organic acid excretion is not certain. However, a large body of indirect evidence supports the concept that some of these acids, besides undergoing glomerular filtration and tubular reabsorption, are produced in the renal tubular cells and secreted into the urine. It is supposed that it is this tubular synthesis that is sensitive to pH changes within the cells and thus affects the changing rates of organic acid excretion. Such would appear to be the case for citrate and a-ketoglutarate although direct evidence for their tubular secretion is not available. In the case of malic acid, however, such evidence is available and constitutes the main subject of the present paper. In 1953 Craig, Miller, Owens and Woodward reported (8) that during the intravenous infusion of sodium salts of either a-ketoglutaric or succinic acids in dogs there was both glomerular filtration and net tubular secretion of malic acid. Under these circumstances they found that the infusion of malonic acid, the succinoxidase inhibitor, caused an abrupt change in the pattern of malic acid excretion to one of glomerular filtration with net tubular reabsorption. It is the purpose of the present paper to report experiments on malic acid excretion in the dog that confirm and extend these findings of Craig and co-workers and include a description of the varying patterns of malic acid excretion during

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@article{VISHWAKARMA1959TheEO, title={The excretion of I-malic acid in relation to the tricarboxylic acid cycle in the kidney.}, author={P VISHWAKARMA and W. D. Lotspeich}, journal={The Journal of clinical investigation}, year={1959}, volume={38 2}, pages={414-23} }