Basal muscle amino acid kinetics and protein synthesis in healthy young and older men

Elena Volpi, Melinda Sheffield-Moore, Blake Rasmussen, Robert R. Wolfe

Research output: Contribution to journalArticle

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Abstract

Context: Sarcopenia is associated with loss of strength and function, eventually leading to loss of independence. Some studies suggest that basal muscle protein turnover is reduced with aging, but other studies do not confirm this finding. Objective: To determine if aging per se affects basal muscle protein turnover in men. Design and Setting: Cross-sectional study conducted from June 1997 to July 2000 in a general US community. Participants: Twenty-six young (mean [SE] age, 28 [2] years) and 22 older (mean [SE] age, 70 [1] years) men, who were healthy and independent based on activities of daily living, physical examinations, and screening tests. Subjects were excluded if they had cardiac, pulmonary, liver, or kidney disease; any impairment in activities of daily living; or steroid use. Main Outcome Measures: We measured basal muscle protein and amino acid kinetics, based on stable isotope techniques with femoral arteriovenous catheterization and muscle biopsies. Three models (arteriovenous balance, three-pool, and fractional synthesis rate) were used to estimate the metabolic parameters. Results: Mean (SE) total leg volume was 9.60 (0.32) L in older men vs 10.83 (0.43) L in younger men, which suggests muscle loss in the older men. Net muscle protein balance was similar in both groups (older men,-19 [2] nmol/min per 100 mL of leg volume vs younger men,-21 [2] nmol/min per 100 mL of leg volume; P= .51). Small differences were found in mean (SE) muscle protein synthesis in comparisons of older vs younger men: arteriovenous balance, 48 (5) nmol/min per 100 mL of leg volume vs 32 (3) nmol/min per 100 mL of leg volume; P=.004; three-pool, 58 (5) nmol/min per 100 mL of leg volume vs 43 (4) nmol/min per 100 mL of leg volume; P=.04; and fractional synthesis rate, 0.0601 (0.0046) %/h vs 0.0578 (0.0047) %/h; P=.73. Small differences were also found in mean (SE) muscle protein breakdown: arteriovenous balance, 66 (5) nmol/min per 100 mL of leg volume in older vs 53 (4) nmol/min per 100 mL of leg volume in younger men, P=.045; and three-pool, 76 (6) nmol/min per 100 mL of leg volume vs 64 (5) nmol/min per 100 mL of leg volume, P=.14. Conclusion: Differences in basal muscle protein turnover between older and younger men do not appear to explain muscle loss that occurs with age.

Original languageEnglish (US)
Pages (from-to)1206-1212
Number of pages7
JournalJournal of the American Medical Association
Volume286
Issue number10
StatePublished - Sep 12 2001

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Leg
Muscle Proteins
Amino Acids
Muscles
Proteins
Activities of Daily Living
Sarcopenia
Kidney Diseases
Thigh
Catheterization
Isotopes
Lung Diseases
Physical Examination
Liver Diseases
Cross-Sectional Studies
Steroids
Outcome Assessment (Health Care)
Biopsy

ASJC Scopus subject areas

  • Medicine(all)

Cite this

Basal muscle amino acid kinetics and protein synthesis in healthy young and older men. / Volpi, Elena; Sheffield-Moore, Melinda; Rasmussen, Blake; Wolfe, Robert R.

In: Journal of the American Medical Association, Vol. 286, No. 10, 12.09.2001, p. 1206-1212.

Research output: Contribution to journalArticle

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abstract = "Context: Sarcopenia is associated with loss of strength and function, eventually leading to loss of independence. Some studies suggest that basal muscle protein turnover is reduced with aging, but other studies do not confirm this finding. Objective: To determine if aging per se affects basal muscle protein turnover in men. Design and Setting: Cross-sectional study conducted from June 1997 to July 2000 in a general US community. Participants: Twenty-six young (mean [SE] age, 28 [2] years) and 22 older (mean [SE] age, 70 [1] years) men, who were healthy and independent based on activities of daily living, physical examinations, and screening tests. Subjects were excluded if they had cardiac, pulmonary, liver, or kidney disease; any impairment in activities of daily living; or steroid use. Main Outcome Measures: We measured basal muscle protein and amino acid kinetics, based on stable isotope techniques with femoral arteriovenous catheterization and muscle biopsies. Three models (arteriovenous balance, three-pool, and fractional synthesis rate) were used to estimate the metabolic parameters. Results: Mean (SE) total leg volume was 9.60 (0.32) L in older men vs 10.83 (0.43) L in younger men, which suggests muscle loss in the older men. Net muscle protein balance was similar in both groups (older men,-19 [2] nmol/min per 100 mL of leg volume vs younger men,-21 [2] nmol/min per 100 mL of leg volume; P= .51). Small differences were found in mean (SE) muscle protein synthesis in comparisons of older vs younger men: arteriovenous balance, 48 (5) nmol/min per 100 mL of leg volume vs 32 (3) nmol/min per 100 mL of leg volume; P=.004; three-pool, 58 (5) nmol/min per 100 mL of leg volume vs 43 (4) nmol/min per 100 mL of leg volume; P=.04; and fractional synthesis rate, 0.0601 (0.0046) {\%}/h vs 0.0578 (0.0047) {\%}/h; P=.73. Small differences were also found in mean (SE) muscle protein breakdown: arteriovenous balance, 66 (5) nmol/min per 100 mL of leg volume in older vs 53 (4) nmol/min per 100 mL of leg volume in younger men, P=.045; and three-pool, 76 (6) nmol/min per 100 mL of leg volume vs 64 (5) nmol/min per 100 mL of leg volume, P=.14. Conclusion: Differences in basal muscle protein turnover between older and younger men do not appear to explain muscle loss that occurs with age.",
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AU - Volpi, Elena

AU - Sheffield-Moore, Melinda

AU - Rasmussen, Blake

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N2 - Context: Sarcopenia is associated with loss of strength and function, eventually leading to loss of independence. Some studies suggest that basal muscle protein turnover is reduced with aging, but other studies do not confirm this finding. Objective: To determine if aging per se affects basal muscle protein turnover in men. Design and Setting: Cross-sectional study conducted from June 1997 to July 2000 in a general US community. Participants: Twenty-six young (mean [SE] age, 28 [2] years) and 22 older (mean [SE] age, 70 [1] years) men, who were healthy and independent based on activities of daily living, physical examinations, and screening tests. Subjects were excluded if they had cardiac, pulmonary, liver, or kidney disease; any impairment in activities of daily living; or steroid use. Main Outcome Measures: We measured basal muscle protein and amino acid kinetics, based on stable isotope techniques with femoral arteriovenous catheterization and muscle biopsies. Three models (arteriovenous balance, three-pool, and fractional synthesis rate) were used to estimate the metabolic parameters. Results: Mean (SE) total leg volume was 9.60 (0.32) L in older men vs 10.83 (0.43) L in younger men, which suggests muscle loss in the older men. Net muscle protein balance was similar in both groups (older men,-19 [2] nmol/min per 100 mL of leg volume vs younger men,-21 [2] nmol/min per 100 mL of leg volume; P= .51). Small differences were found in mean (SE) muscle protein synthesis in comparisons of older vs younger men: arteriovenous balance, 48 (5) nmol/min per 100 mL of leg volume vs 32 (3) nmol/min per 100 mL of leg volume; P=.004; three-pool, 58 (5) nmol/min per 100 mL of leg volume vs 43 (4) nmol/min per 100 mL of leg volume; P=.04; and fractional synthesis rate, 0.0601 (0.0046) %/h vs 0.0578 (0.0047) %/h; P=.73. Small differences were also found in mean (SE) muscle protein breakdown: arteriovenous balance, 66 (5) nmol/min per 100 mL of leg volume in older vs 53 (4) nmol/min per 100 mL of leg volume in younger men, P=.045; and three-pool, 76 (6) nmol/min per 100 mL of leg volume vs 64 (5) nmol/min per 100 mL of leg volume, P=.14. Conclusion: Differences in basal muscle protein turnover between older and younger men do not appear to explain muscle loss that occurs with age.

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