title: Proapoptotic factor Bax is increased in satellite cells in the tibialis anterior muscles of old rats.
abstract: Aging impairs the ability of muscle to adapt to exercise or injury. The goal of this study was to determine whether age-related changes in muscle adaptability could be the result of satellite cell apoptosis. Ten days after exposure to an injury protocol, estimates of edema in the exposed tibialis anterior muscles were higher in old (30 months) than young (3 months) rats, and isometric force levels were lower in old rats. Both young and old rats displayed an increase in MyoD labeling in the exposed muscle, indicating that injury induced satellite-cell activation. However, there were more MyoD-labeled cells that coexpressed the proapoptotic factor, Bax, in old than in young rats, suggesting that decrements in muscle recovery may be associated with an increase in satellite-cell apoptosis. Based on these findings we conclude that reducing satellite-cell apoptosis in aged animals may improve muscle recovery after injury.
authors.affiliation: Engineering and Controls Technology Branch, National Institute for Occupational Safety and Health, 1095 Willowdale Rd., MS 2027, Morgantown, West Virginia 26505, USA. ksk1@cdc.gov
authors.forename: Kristine
authors.initials: K
authors.lastname: Krajnak
authors.forename: Stacey
authors.initials: S
authors.lastname: Waugh
authors.forename: Roger
authors.initials: R
authors.lastname: Miller
authors.forename: Brent
authors.initials: B
authors.lastname: Baker
authors.forename: Kenneth
authors.initials: K
authors.lastname: Geronilla
authors.forename: Stephen E
authors.initials: SE
authors.lastname: Alway
authors.forename: Robert G
authors.initials: RG
authors.lastname: Cutlip
mesh_terms: D000222:Adaptation, Physiological; D000367:Age Factors; D000375:Aging / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D000818:Animals; D017209:Apoptosis; D005080:Exercise Test; D007150:Immunohistochemistry; D007537:Isometric Contraction / Q000235:genetics / Q000502:physiology; D008297:Male; D018482:Muscle, Skeletal / Q000166:cytology / Q000293:injuries / Q000502:physiology*; D017570:MyoD Protein / Q000032:analysis / Q000378:metabolism; D009929:Organ Size; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D011919:Rats, Inbred Strains; D012038:Regeneration; D020133:Reverse Transcriptase Polymerase Chain Reaction; D032496:Satellite Cells, Skeletal Muscle / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D014158:Transcription, Genetic; D015854:Up-Regulation; D051028:bcl-2-Associated X Protein / Q000032:analysis / Q000235:genetics / Q000378:metabolism*
chemical_list: D017570:MyoD Protein; D012333:RNA, Messenger; D051028:bcl-2-Associated X Protein