AJP - Endocrinology and Metabolism, Vol 262, Issue 2 E203-E210, Copyright © 1992 by American Physiological Society

ARTICLES

Effects of insulin and amino acid infusion on leucine and phenylalanine kinetics in type 1 diabetes

S. Inchiostro, G. Biolo, D. Bruttomesso, C. Fongher, L. Sabadin, M. Carlini, E. Duner, A. Tiengo and P. Tessari
Cattedra di Malattie di Ricambio, University of Padua, Italy.

To evaluate the anabolic effects of hyperinsulinemia and hyperaminoacidemia on amino acid (and protein) metabolism in type 1 (insulin-dependent) diabetes mellitus (IDDM), we studied leucine and phenylalanine kinetics in nine IDDM and seven control subjects, both at basal euglycemic conditions and during a euglycemic hyperinsulinemic clamp (approximately 60-80 microU/ml of plasma free insulin), combined with an intravenous infusion of amino acids (AA), which doubled plasma concentrations of most AA. In the basal state, euglycemia was maintained in IDDM subjects at the expense of a peripheral free insulin level (16 +/- 2 microU/ml) greater (P less than 0.05) than controls (9 +/- 1 microU/ml). Despite that, leucine rate of appearance (Ra), alpha-ketoisocaproate oxidation (approximating leucine-carbon oxidation), and nonoxidative leucine disposal, were greater (P less than 0.05) in IDDM than in control subjects. Phenylalanine Ra was slightly but not significantly greater in IDDM vs. control subjects. During the clamp, at comparable plasma free insulin and amino acid concentrations, oxidation was similar in the two groups, endogenous leucine and phenylalanine Ra remained significantly greater (P less than 0.05) in IDDM than in normal subjects, and leucine disposal tended also to be greater in IDDM subjects. Thus, in IDDM subjects maintained at euglycemia, endogenous Ra of essential amino acid(s) (index of endogenous proteolysis) is increased, both in the postabsorptive state and after hyperinsulinemia combined with hyperaminoacidemia, while leucine utilization for protein synthesis is not impaired.

This article has been cited by other articles:

				P. Tessari, E. Kiwanuka, A. Coracina, M. Zaramella, M. Vettore, A. Valerio, and G. Garibotto Insulin in methionine and homocysteine kinetics in healthy humans: plasma vs. intracellular models Am J Physiol Endocrinol Metab, June 1, 2005; 288(6): E1270 - E1276. [Abstract] [Full Text] [PDF]

				A. P. Richardson and J. A. Tayek Type 2 diabetic patients may have a mild form of an injury response: a clinical research center study Am J Physiol Endocrinol Metab, June 1, 2002; 282(6): E1286 - E1290. [Abstract] [Full Text] [PDF]

				P. G. Whittaker, C. H. Lee, and R. Taylor Whole body protein kinetics in women: effect of pregnancy and IDDM during anabolic stimulation Am J Physiol Endocrinol Metab, November 1, 2000; 279(5): E978 - E988. [Abstract] [Full Text] [PDF]

				M. Charlton and K. S. Nair Protein Metabolism in Insulin-Dependent Diabetes Mellitus J. Nutr., February 1, 1998; 128(2): 323 - 323. [Abstract] [Full Text]

				P. De Feo Fed State Protein Metabolism in Diabetes Mellitus J. Nutr., February 1, 1998; 128(2): 328 - 328. [Abstract] [Full Text]