Aging differentially affects human skeletal muscle amino acid transporter expression when essential amino acids are ingested after exercise

Jared M. Dickinson; Micah J. Drummond; Jennifer R. Coben; Elena Volpi; Blake B. Rasmussen

doi:10.1016/j.clnu.2012.07.009

Aging differentially affects human skeletal muscle amino acid transporter expression when essential amino acids are ingested after exercise

Jared M. Dickinson, Micah J. Drummond, Jennifer R. Coben, Elena Volpi, Blake B. Rasmussen

Research output: Contribution to journal › Article › peer-review

62 Scopus citations

Abstract

Background & aims: Amino acid transporters have been proposed as regulators of protein synthesis. The primary aim of this study was to determine whether amino acid transporter expression is increased in human muscle following resistance exercise (RE) coupled with essential amino acid (EAA) ingestion, and whether a differential response occurs with aging. Secondly, we aimed to compare this response to a previous study examining RE alone. Methods: Young (n = 7, 30 ± 2 yr) and older men (n = 6, 70 ± 2 yr) ingested EAA 1 h after RE. Muscle biopsies were obtained at rest and 3 and 6 h post exercise to examine amino acid transporter mRNA and protein expression. Results: In both age groups, RE + EAA increased mRNA of L-type amino acid transporter 1 (LAT1)/solute linked carrier (SLC)7A5, sodium-coupled neutral amino acid transporter 2 (SNAT2)/SLC38A2, and cationic amino acid transporter 1/SLC7A1 (p < 0.05). SNAT2 protein increased in young at 3 and 6 h (p < 0.05), whereas old maintained higher LAT1 protein (p < 0.05). Compared to RE alone, RE + EAA enhanced amino acid transporter expression only in young (p < 0.05). Conclusions: RE increases muscle amino acid transporter expression in young and older adults, however, post exercise EAA ingestion enhances amino acid transporter expression only in young indicating that aging may influence the function of specific amino acid transporters.

Original language	English (US)
Pages (from-to)	273-280
Number of pages	8
Journal	Clinical Nutrition
Volume	32
Issue number	2
DOIs	https://doi.org/10.1016/j.clnu.2012.07.009
State	Published - Apr 2013
Externally published	Yes

Keywords

MTORC1 signaling
Muscle protein synthesis
Nutrition
Resistance exercise
Sarcopenia

ASJC Scopus subject areas

Nutrition and Dietetics
Critical Care and Intensive Care Medicine

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10.1016/j.clnu.2012.07.009

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@article{da077fbe0bef4d02a9800fb75c2067fd,

title = "Aging differentially affects human skeletal muscle amino acid transporter expression when essential amino acids are ingested after exercise",

abstract = "Background & aims: Amino acid transporters have been proposed as regulators of protein synthesis. The primary aim of this study was to determine whether amino acid transporter expression is increased in human muscle following resistance exercise (RE) coupled with essential amino acid (EAA) ingestion, and whether a differential response occurs with aging. Secondly, we aimed to compare this response to a previous study examining RE alone. Methods: Young (n = 7, 30 ± 2 yr) and older men (n = 6, 70 ± 2 yr) ingested EAA 1 h after RE. Muscle biopsies were obtained at rest and 3 and 6 h post exercise to examine amino acid transporter mRNA and protein expression. Results: In both age groups, RE + EAA increased mRNA of L-type amino acid transporter 1 (LAT1)/solute linked carrier (SLC)7A5, sodium-coupled neutral amino acid transporter 2 (SNAT2)/SLC38A2, and cationic amino acid transporter 1/SLC7A1 (p < 0.05). SNAT2 protein increased in young at 3 and 6 h (p < 0.05), whereas old maintained higher LAT1 protein (p < 0.05). Compared to RE alone, RE + EAA enhanced amino acid transporter expression only in young (p < 0.05). Conclusions: RE increases muscle amino acid transporter expression in young and older adults, however, post exercise EAA ingestion enhances amino acid transporter expression only in young indicating that aging may influence the function of specific amino acid transporters.",

keywords = "MTORC1 signaling, Muscle protein synthesis, Nutrition, Resistance exercise, Sarcopenia",

author = "Dickinson, {Jared M.} and Drummond, {Micah J.} and Coben, {Jennifer R.} and Elena Volpi and Rasmussen, {Blake B.}",

note = "Funding Information: We thank the subjects for their participation. We also thank Junfung Hao for technical assistance. This study was supported by the NIH / National Institute of Arthritis and Musculoskeletal and Skin Diseases grant R01AR049877 , NIH/ National Institute on Aging P30AG024832 , R01AG018311 , and T35AG038048 , and National Institute on Disability and Rehabilitation Research H133P110012 . This study was conducted with the support of the Institute for Translational Sciences at the University of Texas Medical Branch , supported in part by a Clinical and Translational Science Award ( UL1TR000071 ) from the National Center for Advancing Translational Sciences , National Institutes of Health.",

year = "2013",

month = apr,

doi = "10.1016/j.clnu.2012.07.009",

language = "English (US)",

volume = "32",

pages = "273--280",

journal = "Clinical Nutrition",

issn = "0261-5614",

publisher = "Churchill Livingstone",

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TY - JOUR

T1 - Aging differentially affects human skeletal muscle amino acid transporter expression when essential amino acids are ingested after exercise

AU - Dickinson, Jared M.

AU - Drummond, Micah J.

AU - Coben, Jennifer R.

AU - Volpi, Elena

AU - Rasmussen, Blake B.

N1 - Funding Information: We thank the subjects for their participation. We also thank Junfung Hao for technical assistance. This study was supported by the NIH / National Institute of Arthritis and Musculoskeletal and Skin Diseases grant R01AR049877 , NIH/ National Institute on Aging P30AG024832 , R01AG018311 , and T35AG038048 , and National Institute on Disability and Rehabilitation Research H133P110012 . This study was conducted with the support of the Institute for Translational Sciences at the University of Texas Medical Branch , supported in part by a Clinical and Translational Science Award ( UL1TR000071 ) from the National Center for Advancing Translational Sciences , National Institutes of Health.

PY - 2013/4

Y1 - 2013/4

N2 - Background & aims: Amino acid transporters have been proposed as regulators of protein synthesis. The primary aim of this study was to determine whether amino acid transporter expression is increased in human muscle following resistance exercise (RE) coupled with essential amino acid (EAA) ingestion, and whether a differential response occurs with aging. Secondly, we aimed to compare this response to a previous study examining RE alone. Methods: Young (n = 7, 30 ± 2 yr) and older men (n = 6, 70 ± 2 yr) ingested EAA 1 h after RE. Muscle biopsies were obtained at rest and 3 and 6 h post exercise to examine amino acid transporter mRNA and protein expression. Results: In both age groups, RE + EAA increased mRNA of L-type amino acid transporter 1 (LAT1)/solute linked carrier (SLC)7A5, sodium-coupled neutral amino acid transporter 2 (SNAT2)/SLC38A2, and cationic amino acid transporter 1/SLC7A1 (p < 0.05). SNAT2 protein increased in young at 3 and 6 h (p < 0.05), whereas old maintained higher LAT1 protein (p < 0.05). Compared to RE alone, RE + EAA enhanced amino acid transporter expression only in young (p < 0.05). Conclusions: RE increases muscle amino acid transporter expression in young and older adults, however, post exercise EAA ingestion enhances amino acid transporter expression only in young indicating that aging may influence the function of specific amino acid transporters.

AB - Background & aims: Amino acid transporters have been proposed as regulators of protein synthesis. The primary aim of this study was to determine whether amino acid transporter expression is increased in human muscle following resistance exercise (RE) coupled with essential amino acid (EAA) ingestion, and whether a differential response occurs with aging. Secondly, we aimed to compare this response to a previous study examining RE alone. Methods: Young (n = 7, 30 ± 2 yr) and older men (n = 6, 70 ± 2 yr) ingested EAA 1 h after RE. Muscle biopsies were obtained at rest and 3 and 6 h post exercise to examine amino acid transporter mRNA and protein expression. Results: In both age groups, RE + EAA increased mRNA of L-type amino acid transporter 1 (LAT1)/solute linked carrier (SLC)7A5, sodium-coupled neutral amino acid transporter 2 (SNAT2)/SLC38A2, and cationic amino acid transporter 1/SLC7A1 (p < 0.05). SNAT2 protein increased in young at 3 and 6 h (p < 0.05), whereas old maintained higher LAT1 protein (p < 0.05). Compared to RE alone, RE + EAA enhanced amino acid transporter expression only in young (p < 0.05). Conclusions: RE increases muscle amino acid transporter expression in young and older adults, however, post exercise EAA ingestion enhances amino acid transporter expression only in young indicating that aging may influence the function of specific amino acid transporters.

KW - MTORC1 signaling

KW - Muscle protein synthesis

KW - Nutrition

KW - Resistance exercise

KW - Sarcopenia

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SN - 0261-5614

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JO - Clinical Nutrition

JF - Clinical Nutrition

IS - 2

ER -

Aging differentially affects human skeletal muscle amino acid transporter expression when essential amino acids are ingested after exercise

Abstract

Keywords

ASJC Scopus subject areas

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