Oral and intravenously administered amino acids produce similar effects on muscle protein synthesis in the elderly

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Abstract

BACKGROUND: Muscle protein synthesis is stimulated in the elderly when amino acid availability is increased. OBJECTIVE: To determine which mode of delivery of amino acids (intravenous vs. oral ingestion) is more effective in stimulating the rate of muscle protein synthesis in elderly subjects. DESIGN: Fourteen elderly subjects were assigned to one of two groups. Following insertion of femoral arterial and venous catheters, subjects were infused with a primed, continuous infusion of L-[ring-2H5] phenylalanine. Blood samples and muscle biopsies were obtained to measure muscle protein fractional synthesis rate (FSR) with the precursor-product model, phenylalanine kinetics across the leg with the three-pool model, and whole body phenylalanine kinetics. Protein metabolism parameters were measured in the basal period, and during the administration of oral amino acids (n=8) or a similar amount of intravenous amino acids (n=6). RESULTS: Enteral and parenteral amino acid administration increased amino acid arterial concentrations and delivery to the leg to a similar extent in both groups. Muscle protein synthesis as measured by both FSR, and the three-pool model, increased during amino acid administration (P < 0.05 vs. basal) in both groups with no differences between groups. Whole body proteolysis did not change with the oral amino acids whereas it increased slightly during parenteral amino acid administration. CONCLUSIONS: Increased amino acid availability stimulates the rate of muscle protein synthesis independent of the route of administration (enteral vs. parenteral).

Original languageEnglish (US)
Pages (from-to)358-362
Number of pages5
JournalJournal of Nutrition, Health and Aging
Volume6
Issue number6
StatePublished - 2002

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Muscle Proteins
muscle protein
mouth
protein synthesis
Amino Acids
amino acids
Phenylalanine
fractional synthesis rate
phenylalanine
Small Intestine
Leg
legs
kinetics
thighs
Thigh
protein metabolism
catheters
proteolysis
oral administration
Proteolysis

Keywords

  • Aging
  • Amino acids
  • Muscle protein synthesis
  • Stable isotopes

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Aging
  • Endocrinology
  • Food Science

Cite this

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title = "Oral and intravenously administered amino acids produce similar effects on muscle protein synthesis in the elderly",
abstract = "BACKGROUND: Muscle protein synthesis is stimulated in the elderly when amino acid availability is increased. OBJECTIVE: To determine which mode of delivery of amino acids (intravenous vs. oral ingestion) is more effective in stimulating the rate of muscle protein synthesis in elderly subjects. DESIGN: Fourteen elderly subjects were assigned to one of two groups. Following insertion of femoral arterial and venous catheters, subjects were infused with a primed, continuous infusion of L-[ring-2H5] phenylalanine. Blood samples and muscle biopsies were obtained to measure muscle protein fractional synthesis rate (FSR) with the precursor-product model, phenylalanine kinetics across the leg with the three-pool model, and whole body phenylalanine kinetics. Protein metabolism parameters were measured in the basal period, and during the administration of oral amino acids (n=8) or a similar amount of intravenous amino acids (n=6). RESULTS: Enteral and parenteral amino acid administration increased amino acid arterial concentrations and delivery to the leg to a similar extent in both groups. Muscle protein synthesis as measured by both FSR, and the three-pool model, increased during amino acid administration (P < 0.05 vs. basal) in both groups with no differences between groups. Whole body proteolysis did not change with the oral amino acids whereas it increased slightly during parenteral amino acid administration. CONCLUSIONS: Increased amino acid availability stimulates the rate of muscle protein synthesis independent of the route of administration (enteral vs. parenteral).",
keywords = "Aging, Amino acids, Muscle protein synthesis, Stable isotopes",
author = "Blake Rasmussen and Wolfe, {R. R.} and Elena Volpi",
year = "2002",
language = "English (US)",
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T1 - Oral and intravenously administered amino acids produce similar effects on muscle protein synthesis in the elderly

AU - Rasmussen, Blake

AU - Wolfe, R. R.

AU - Volpi, Elena

PY - 2002

Y1 - 2002

N2 - BACKGROUND: Muscle protein synthesis is stimulated in the elderly when amino acid availability is increased. OBJECTIVE: To determine which mode of delivery of amino acids (intravenous vs. oral ingestion) is more effective in stimulating the rate of muscle protein synthesis in elderly subjects. DESIGN: Fourteen elderly subjects were assigned to one of two groups. Following insertion of femoral arterial and venous catheters, subjects were infused with a primed, continuous infusion of L-[ring-2H5] phenylalanine. Blood samples and muscle biopsies were obtained to measure muscle protein fractional synthesis rate (FSR) with the precursor-product model, phenylalanine kinetics across the leg with the three-pool model, and whole body phenylalanine kinetics. Protein metabolism parameters were measured in the basal period, and during the administration of oral amino acids (n=8) or a similar amount of intravenous amino acids (n=6). RESULTS: Enteral and parenteral amino acid administration increased amino acid arterial concentrations and delivery to the leg to a similar extent in both groups. Muscle protein synthesis as measured by both FSR, and the three-pool model, increased during amino acid administration (P < 0.05 vs. basal) in both groups with no differences between groups. Whole body proteolysis did not change with the oral amino acids whereas it increased slightly during parenteral amino acid administration. CONCLUSIONS: Increased amino acid availability stimulates the rate of muscle protein synthesis independent of the route of administration (enteral vs. parenteral).

AB - BACKGROUND: Muscle protein synthesis is stimulated in the elderly when amino acid availability is increased. OBJECTIVE: To determine which mode of delivery of amino acids (intravenous vs. oral ingestion) is more effective in stimulating the rate of muscle protein synthesis in elderly subjects. DESIGN: Fourteen elderly subjects were assigned to one of two groups. Following insertion of femoral arterial and venous catheters, subjects were infused with a primed, continuous infusion of L-[ring-2H5] phenylalanine. Blood samples and muscle biopsies were obtained to measure muscle protein fractional synthesis rate (FSR) with the precursor-product model, phenylalanine kinetics across the leg with the three-pool model, and whole body phenylalanine kinetics. Protein metabolism parameters were measured in the basal period, and during the administration of oral amino acids (n=8) or a similar amount of intravenous amino acids (n=6). RESULTS: Enteral and parenteral amino acid administration increased amino acid arterial concentrations and delivery to the leg to a similar extent in both groups. Muscle protein synthesis as measured by both FSR, and the three-pool model, increased during amino acid administration (P < 0.05 vs. basal) in both groups with no differences between groups. Whole body proteolysis did not change with the oral amino acids whereas it increased slightly during parenteral amino acid administration. CONCLUSIONS: Increased amino acid availability stimulates the rate of muscle protein synthesis independent of the route of administration (enteral vs. parenteral).

KW - Aging

KW - Amino acids

KW - Muscle protein synthesis

KW - Stable isotopes

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