Role of kidney in gluconeogenesis and amino acid catabolism.

SZEPESI, B., E, H. AVERY, AND R. A. FREEDLAND. RoZe of kidney in gluconeugenesis and amino acid catabolism. Am. J. Physiol. 2 19 (6) : 1627-1631. 1970--The enzyme profiles of rat liver and kidney were studied in five different conditions: a) high-carbohydrate, protein-free diet, b) high-carbohydrate (adequate protein) diet with or without exogenous hydrocortisone, and c) high-protein, carbohydrate-free diet with or without exogenous hydrocortisone. In the liver gluconeogenic stimuli increased the level of enzymes associated with gluconeogenesis and amino acid catabolism, whereas in the kidney the principal effects of these stimuli were to increase the levels of enzymes associated with gluconeogenesis. Tyrosine-a-ketogIutarate transaminase, glutamic-pyruvic transaminase, and serine dehydrase activities were below the level of detection in kidney and were not inducible. Gluconeogenic enzymes in the kidney were found to be localized primarily in the cortex, whereas urea cycle enzymes were found to be localized in the medulla, except arginase, which is found in both cortex and medulla. The data suggest that the kidney is more a gluconeogenic organ than the site of substantial amino acid catabolism and that the kidney may be a source of endogenous arginine.