Aging does not impair the anabolic response to a protein-rich meal.
Am J Clin Nutr
; 86(2): 451-6, 2007 Aug.
Article
em En
| MEDLINE
| ID: mdl-17684218
ABSTRACT
BACKGROUND:
Sarcopenia is a debilitating condition afflicting the elderly that may be facilitated by insufficient or ineffectual intake of dietary protein. We previously showed that free-form essential amino acids acutely stimulate muscle protein synthesis in both the young and the elderly. However, the ability of an actual protein-rich food to stimulate anabolism in the young and the elderly has not been explored.OBJECTIVE:
We aimed to characterize changes in plasma amino acid concentrations and to quantify muscle protein synthesis in healthy young (41 +/- 8 y old; n = 10) and elderly (70 +/- 5 y old; n = 10) persons after ingestion of a 113-g (4-oz) serving of lean beef.DESIGN:
Venous blood samples and vastus lateralis muscle biopsy samples were obtained during a primed (2.0 mumol/kg) constant infusion (0.08 mumol.kg(-1).min(-1)) of l-[ring-(13)C(6)] phenylalanine. Plasma amino acid concentrations were measured and a mixed-muscle fractional synthesis rate (FSR) was calculated during the premeal period and for 5 h after beef ingestion.RESULTS:
Mixed-muscle FSR increased by approximately 51% in both the elderly (mean +/- SE measurements 0.072 +/- 0.004%/h and 0.108 +/- 0.006%/h before and after the meal, respectively) and the young (0.074 +/- 0.005%/h and 0.113 +/- 0.005%/h before and after the meal, respectively) after beef ingestion (P < 0.001). Plasma amino acid concentrations peaked at approximately 100 min after beef ingestion in both age groups but were substantially higher in the elderly (2185 +/- 134 nmol/mL compared with 1403 +/- 96 nmol/mL; P < 0.001).CONCLUSION:
Despite differences in the concentration of amino acids in the plasma precursor pool, aging does not impair the ability to acutely synthesize muscle protein after ingestion of a common protein-rich food.
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Base de dados:
MEDLINE
Assunto principal:
Envelhecimento
/
Proteínas Alimentares
/
Aminoácidos
Limite:
Adult
/
Aged
/
Female
/
Humans
/
Male
/
Middle aged
Idioma:
En
Ano de publicação:
2007
Tipo de documento:
Article