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.
Dissociation of the effects of epinephrine and insulin on glucose and protein metabolism / P. Castellino, L. Luzi, S. Del Prato, R.A. DeFronzo. - In: AMERICAN JOURNAL OF PHYSIOLOGY. - ISSN 0002-9513. - 258:1 21-1(1990), pp. E117-E125. [10.1152/ajpendo.1990.258.1.e117]
Dissociation of the effects of epinephrine and insulin on glucose and protein metabolism
L. Luzi;
1990
Abstract
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.File | Dimensione | Formato | |
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