Metabolic interactions of amino acids and glucose in healthy humans

E. Ferrannini, S. Bevilacqua, L. Lanzone, R. Bonadonna, L. Brandi, M. Oleggini, C. Boni, G. Buzzigoli, D. Ciociaro, L. Luzi, R. A. De Fronzo

Research output: Contribution to journalArticlepeer-review

23 Scopus citations

Abstract

Glucose and non-esterified fatty acids (NEFA) compete for utilization by insulin-sensitive tissues. To test whether a similar competition exists between amino acids and glucose, we infused an amino acid solution (Freamine, 0.7 g/kg) or saline during a euglycaemic insulin (1 mU/min/kg) clamp in paired fashion in a group of young, healthy volunteers. Amino acids stimulated insulin secretion (100 ± 8 vs 60 ± 5 μU/ml, p < 0.001) and inhibited whole-body glucose disposal by 26 ± 6% (24.6 ± 2.0 vs 32.7 ± 2.2 μmol/min/kg, p < 0.01). Amino acid infusion did not interfere with insulin-induced suppression of endogenous glucose production. Basal protein oxidation (estimated from urinary nitrogen excretion, 7.0 ± 0.9 μmol/min/kg) fell to 3.2 ± 1.6 μmol/min/kg (p < 0.05) during saline infusion, and increased to 13.3 ± 0.7 μmol/min/kg (p < 0.05) with amino acid administration. Correspondingly, net carbohydrate oxidation (by indirect calorimetry) rose from 6.1 ± 1.7 to 19.5 ± 1.7 μmol/min/kg (p < 0.005) under control conditions, but only from 9.1 ± 1.6 to 15.5 ± 1.2 μmol/min/kg (p < 0.05) with amino acids; thus, insulin-induced glucose oxidation was significantly inhibited by amino acid (by 7 μmol/min/kg on the average, p < 0.05). In contrast, the ability of insulin to suppress nett lipid oxidation and to enhance non-oxidative glucose disposal was not altered by amino acid infusion. A strong thermogenic effect of the infused amino acid load was documented by a rise in energy production rate from 1.11 to 1.35 kcal/min during the 2nd hour of the clamp (p < 0.01); over 2 hr, some 13% of the caloric content of Freamine was expended in this way. We conclude that, under the experimental circumstances of the present study (high amino acid and insulin concentrations) a glucose-amino acid cycle can be demonstrated, the nature and mechanisms of which appear to be essentially analogous to those of the glucose-NEFA cycle.

Original languageEnglish (US)
Pages (from-to)175-186
Number of pages12
JournalDiabetes, Nutrition and Metabolism - Clinical and Experimental
Volume1
Issue number3
StatePublished - Jan 1 1988
Externally publishedYes

ASJC Scopus subject areas

  • Internal Medicine
  • Medicine (miscellaneous)
  • Food Science
  • Endocrinology, Diabetes and Metabolism
  • Endocrinology

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