Leucine incorporation into mixed skeletal muscle protein in humans

K Sreekumaran Nair, D. Halliday, R. C. Griggs

Research output: Contribution to journalArticle

122 Citations (Scopus)

Abstract

Fractional mixed skeletal muscle protein synthesis (FMPS) was estimated in 10 postabsorptive healthy men by determining the increment in the abundance of [13C]leucine in quadriceps muscle protein during an intravenous infusion of L-[1-13C]leucine. FMPS in our subjects was 0.046 ± 0.003%/h. Whole-body muscle protein synthesis (MPS) was calculated based on the estimation of muscle mass from creatinine excretion and compared with whole-body protein synthesis (WBPS) calculated from the nonoxidative portion of leucine flux. A significant correlation (r2 = 0.73, P < 0.05) was found between MPS (44.7 ± 3.4 mg·kg-1 · h-1) and WBPS (167.8 ± 8.5 mg·kg-1·h-1). The contribution of MPS to WBPS was 27 ± 1%, which is comparable to the reports in other species. Morphometric analyses of adjacent muscle samples in eight subjects demonstrated that the biopsy specimens consisted of 86.5 ± 2% muscular as opposed to other tissues. Because fiber type composition varies between biopsies, we examined the relationship between proportions of each fiber and FMPS. Variation in the composition of biopsies and in fiber-type proportion did not affect the estimation of muscle protein synthesis rate. We conclude that stable isotope techniques using serial needle biopsies permit the direct measurement of FMPS in humans and that this estimation is correlated with an indirect estimation of WBPS.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Endocrinology and Metabolism
Volume254
Issue number2
StatePublished - 1988
Externally publishedYes

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Muscle Proteins
Leucine
Skeletal Muscle
Biopsy
Proteins
Muscle
Fibers
Muscles
Quadriceps Muscle
Needle Biopsy
Intravenous Infusions
Isotopes
Creatinine
Chemical analysis
Needles
Tissue

ASJC Scopus subject areas

  • Biochemistry
  • Endocrinology
  • Physiology

Cite this

Leucine incorporation into mixed skeletal muscle protein in humans. / Nair, K Sreekumaran; Halliday, D.; Griggs, R. C.

In: American Journal of Physiology - Endocrinology and Metabolism, Vol. 254, No. 2, 1988.

Research output: Contribution to journalArticle

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