Dissociation of the effects of epinephrine and insulin on glucose and protein metabolism

P. Castellino, L. Luzi, S. Del Prato, R. A. DeFronzo

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32 Scopus citations


The separate and combined effects of insulin and epinephrine on leucine metabolism were examined in healthy young volunteers. Subjects participated in four experimental protocols: 1) euglycemic insulin clamp (+80 μU/ml), 2) epinephrine infusion (50 ng · kg-1 min-1) plus somatostatin with basal replacement of insulin and glucagon, 3) combined epinephrine (50 ng · kg-1 · min-1) plus insulin (+80 μU/ml) infusion, and 4) epinephrine and somatostatin as in study 2 plus basal amino acid replacement. Studies were performed with a prime-continuous infusion of [1-14C]leucine and indirect calorimetry. Our results indicate that 1) hyperinsulinemia causes a generalized decrease in plasma amino acid concentrations, including leucine; 2) the reduction in plasma leucine concentration is primarily due to an inhibition of endogenous leucine flux; nonoxidative leucine disposal decreases after insulin infusion; 3) epinephrine, without change in plasma insulin concentration, reduces plasma amino acid levels; 4) combined epinephrine-insulin infusion causes a greater decrease in plasma amino levels than observed with either hormone alone; this is because of a greater inhibition of endogenous leucine flux; and 5) when basal amino acid concentrations are maintained constant with a balanced amino acid infusion, epinephrine inhibits the endogenous leucine flux. In conclusion, the present results do not provide support for the concept that epinephrine is a catabolic hormone with respect to amino acid-protein metabolism. In contrast, epinephrine markedly inhibits insulin-mediated glucose metabolism.

Original languageEnglish (US)
Pages (from-to)E117-E125
JournalAmerican Journal of Physiology - Endocrinology and Metabolism
Issue number1 21-1
StatePublished - 1990


  • leucine turnover

ASJC Scopus subject areas

  • General Medicine


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