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The muscle protein synthetic response to the combined ingestion of protein and carbohydrate is not impaired in healthy older men
Kiskini, Alexandra Hamer, Henrike M. Wall, Benjamin T. Groen, Bart B. L. De Lange, Anneke Bakker, Jaap A. Senden, Joan M. G. Verdijk, Lex B. Van Loon, Luc J.C
Kiskini, Alexandra
Hamer, Henrike M.
Wall, Benjamin T.
Groen, Bart B. L.
De Lange, Anneke
Bakker, Jaap A.
Senden, Joan M. G.
Verdijk, Lex B.
Van Loon, Luc J.C
Abstract
Aging is associated with a progressive decline in skeletal muscle mass. It has been hypothesized that an attenuated muscle protein synthetic response to the main anabolic stimuli may contribute to the age-related loss of muscle tissue. The aim of the present study was to compare the muscle protein synthetic response following ingestion of a meal-like amount of dietary protein plus carbohydrate between healthy young and older men. Twelve young ( 21 ± 1 years ) and 12 older ( 75 ± 1 years ) men consumed 20 g of intrinsically l-[1-13C]phenylalanine-labeled protein with 40 g of carbohydrate. Ingestion of specifically produced intrinsically l-[1-13C]phenylalanine-labeled protein allowed us to assess the subsequent incorporation of casein-derived amino acids into muscle protein. Blood samples were collected at regular intervals, with muscle biopsies obtained prior to and 2 and 6 h after protein plus carbohydrate ingestion. The acute post-prandial rise in plasma glucose and insulin concentrations was significantly greater in the older compared with the younger males. Plasma amino acid concentrations increased rapidly following drink ingestion in both groups. However, plasma leucine concentrations were significantly lower at t = 90 min in the older when compared with the young group ( P < 0.05 ). Muscle protein-bound l-[1-13C]phenylalanine enrichments increased to 0.0071 ± 0.0016 and 0.0072 ± 0.0013 mole percent excess ( MPE ) at 2 h and 0.0229 ± 0.0016 and 0.0213 ± 0.0024 MPE at 6 h following ingestion of the intrinsically labeled protein in the young and older males, respectively, with no differences between groups ( P > 0.05 ). We conclude that the use of dietary protein-derived amino acids for muscle protein synthesis is not impaired in healthy older men following intake of protein plus carbohydrate.
Keywords
skeletal muscle, aging, sarcopenia, amino acids, anabolic resistance
Date
2013
Type
Journal article
Journal
Age
Book
Volume
35
Issue
6
Page Range
2389-2398
Article Number
ACU Department
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Relation URI
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Event URL
Open Access Status
License
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Controlled