Human muscle amino acid transport kinetics in vivo

K. D. Tipton, A. A. Fernando, S. M. Philips, Joaquin Cortiella, D. J. Doyle, R. R. Wolfe

Research output: Contribution to journalArticle

Abstract

In vitro studies of amino acid transport indicate that phenylalanine (Phe) and leucine (Leu) apparently share a common transporter. We studied in vivo transport kinetics of Phe and Leu over a range of arterial concentrations. Healthy volunteers (3 male, 3 female) were studied on each of three occasions while drinking different amino acid solutions to vary arterial amino acid concentrations (Ca). Blood samples were taken from femoral arterial and venous catheters and muscle biopsies were taken from the vastus lateralis during a four h infusion of ring-d5-Phe and 1-13C-Leu. A 3-compartment model of muscle amino acid kinetics was used to determine inward amino acid transport (AT) from Phe and Leu enrichments in artery (Ea) and muscle (Em), as well as Ca and muscle intracellular amino acid concentrations. Linear regression analysis revealed that, while both Phe and Leu AT were significantly (p=0.002 and p=0.03, respectively) related to Phe and Leu Ca (r=0.72 and r=0.54, respectively), the slope of the line was different for Phe (y=5.15x + 136) than for Leu (y=1.84x + 274). Further, Phe Em/Ea, which indicates the fractional contribution of the blood to the intracellular amino acid pool, is significantly (p=0 003) and positively related to Phe Ca, while Leu Em/Ea is not related to Leu Ca. We conclude that,under physiological conditions in vivo, Phe and Leu transport kinetics are different.

Original languageEnglish (US)
JournalFASEB Journal
Volume11
Issue number3
StatePublished - 1997

Fingerprint

Phenylalanine
phenylalanine
Leucine
leucine
Muscle
kinetics
Amino Acids
Muscles
muscles
amino acids
Kinetics
arteries
Arteries
Blood
Biopsy
Catheters
blood
Quadriceps Muscle
thighs
Thigh

ASJC Scopus subject areas

  • Agricultural and Biological Sciences (miscellaneous)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Biochemistry
  • Cell Biology

Cite this

Tipton, K. D., Fernando, A. A., Philips, S. M., Cortiella, J., Doyle, D. J., & Wolfe, R. R. (1997). Human muscle amino acid transport kinetics in vivo. FASEB Journal, 11(3).

Human muscle amino acid transport kinetics in vivo. / Tipton, K. D.; Fernando, A. A.; Philips, S. M.; Cortiella, Joaquin; Doyle, D. J.; Wolfe, R. R.

In: FASEB Journal, Vol. 11, No. 3, 1997.

Research output: Contribution to journalArticle

Tipton, KD, Fernando, AA, Philips, SM, Cortiella, J, Doyle, DJ & Wolfe, RR 1997, 'Human muscle amino acid transport kinetics in vivo', FASEB Journal, vol. 11, no. 3.
Tipton KD, Fernando AA, Philips SM, Cortiella J, Doyle DJ, Wolfe RR. Human muscle amino acid transport kinetics in vivo. FASEB Journal. 1997;11(3).
Tipton, K. D. ; Fernando, A. A. ; Philips, S. M. ; Cortiella, Joaquin ; Doyle, D. J. ; Wolfe, R. R. / Human muscle amino acid transport kinetics in vivo. In: FASEB Journal. 1997 ; Vol. 11, No. 3.
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