Insulin responsiveness of protein metabolism in vivo following bedrest in humans

Journal Article · Sat Oct 01 04:00:00 EDT 1988 · American Journal of Physiology; (USA)

OSTI ID:6252794

Shangraw, R E; Stuart, C A; Prince, M J; Peters, E J; Wolfe, R R ^[1]

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1. Univ. of Texas Medical Branch and Metabolism Unit., Galveston (USA)

To test the influence of bedrest on insulin regulation of leucine metabolism, six normal young men were subjected to a five-step hyperinsulinemic euglycemic clamp before and after 7 days of strict bedrest. A primed-constant infusion of (1-{sup 13}C)leucine was used. Before bedrest, the basal rate of appearance (R{sub a}) of intracellular leucine and leucine oxidation were 2.79{plus minus}0.17 and 0.613{plus minus}0.070 {mu}mol{center dot}kg{sup {minus}1}{center dot}min{sup {minus}1}, respectively. Insulin caused a dose-dependent reduction of the intracellular leucine R{sub a} and leucine oxidation to a minimum of 1.64{plus minus}0.08 and 0.322{plus minus}0.039 {mu}mol{center dot}kg{sup {minus}1}{center dot}min{sup {minus}1}, respectively, in nonbedrested subjects. Insulin also caused a dose-dependent reduction of plasma leucine concentration. After bedrest, subjects exhibited decreased glucose tolerance and increased endogenous insulin secretion, but basal and insulin-suppressed intracellular leucine R{sub a} and leucine oxidation rates were not different from control. Magnetic resonance imaging of the back and lower extremities revealed a 1-4% decrease in muscle volume and a 2-5% increase in fat volume secondary to bedrest. Bedrest also resulted in a negative nitrogen balance as compared with the control period. Thus because negative nitrogen balance and skeletal muscle atrophy occurred in six rested subjects in the absence of changes in the two indices of protein breakdown used in this study, it seems likely that muscle protein synthesis was inhibited.

• OSTI ID: 6252794
• Journal Information: American Journal of Physiology; (USA), Journal Name: American Journal of Physiology; (USA) Vol. 255:4; ISSN 0002-9513; ISSN AJPHA
• Country of Publication: United States
• Language: English

Related Subjects

551001* -- Physiological Systems-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ALDEHYDES
AMINO ACIDS
ANIMALS
ATROPHY
BIOLOGICAL EFFECTS
CARBOHYDRATES
CARBON 13
CARBON ISOTOPES
CARBOXYLIC ACIDS
EVEN-ODD NUCLEI
GLUCOSE
HEXOSES
HORMONES
IN VIVO
INSULIN
ISOTOPES
LEUCINE
LIGHT NUCLEI
MAGNETIC RESONANCE
MALES
MAMMALS
MAN
MEN
METABOLISM
MONOSACCHARIDES
MUSCLES
NUCLEAR MAGNETIC RESONANCE
NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
PATHOLOGICAL CHANGES
PEPTIDE HORMONES
PHYSIOLOGY
PRIMATES
PROTEINS
RESONANCE
SACCHARIDES
SLEEP
STABLE ISOTOPES
VERTEBRATES