PAX7+ satellite cells in young and older adults following resistance exercise.
BACKGROUND
Resistance exercise (RE) stimulates a muscle protein anabolic response partially through enhanced satellite cell (SC) activity, however, age- and gender-related changes in SC content over a 24-h time course are not known.


METHODS
Ten young (27 ± 2 years) men and women and 11 older (70 ± 2 years) men and women performed an acute bout of RE. Myofiber and SC characteristics were determined from muscle biopsies of the vastus lateralis using immunohistochemistry. Immunoblotting was used to determine phosphorylation of cyclin-dependent kinase-2 and protein expression of p27(Kip1) and cyclin D1.


RESULTS
Pax7+ SC were significantly increased in young men 24 h following RE. Percent SC were significantly increased in older women at 6 and 24 h following RE. Aging decreased myonuclear domain and increased protein expression of p27(Kip1) .


CONCLUSIONS
An acute bout of RE increases SC content in young men at 24 h and older women at 6 and 24 h.
Department of Nutrition & Metabolism, University of Texas Medical Branch, 301 University Boulevard, Galveston, Texas 77555, USA.
Dillon K
DK
Walker
Christopher S
CS
Fry
Micah J
MJ
Drummond
Jared M
JM
Dickinson
Kyle L
KL
Timmerman
David M
DM
Gundermann
Kristofer
K
Jennings
Elena
E
Volpi
Blake B
BB
Rasmussen
D000328:Adult; D000367:Age Factors; D000368:Aged; D000375:Aging / Q000378:metabolism*; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D051763:PAX7 Transcription Factor / Q000378:metabolism*; D010766:Phosphorylation; D052097:Quadriceps Muscle / Q000378:metabolism*; D055070:Resistance Training; D032496:Satellite Cells, Skeletal Muscle / Q000378:metabolism*
D051763:PAX7 Transcription Factor; C497321:PAX7 protein, human