title: Effects of microgravity on the mouse triceps brachii muscle.
abstract: BACKGROUND
  In this study we investigated the effects of microgravity on the fiber properties of the mouse triceps brachii, a forelimb muscle that has no antigravity function.
  
  
  METHODS
  Mice (n = 7) were exposed to microgravity for 13 days on the space shuttle Atlantis (Space Transportation System-135). The fiber cross-sectional area (CSA) and succinate dehydrogenase (SDH) staining intensity of the triceps brachii muscle were compared with those of controls (n = 7). SDH activity in this muscle was also estimated.
  
  
  RESULTS
  Microgravity did not affect the body weight, muscle weight, or fiber CSA, but there was reduced SDH staining intensity of all types of fibers, irrespective of the muscle region (P < 0.05). Microgravity also reduced muscle SDH activity (P < 0.05).
  
  
  CONCLUSIONS
  Short-term exposure to microgravity induced a decrease in oxidative capacity, but not atrophy, in the triceps brachii muscle of mice.
authors.affiliation: Laboratory of Cell Biology and Life Science, Graduate School of Human and Environmental Studies, Kyoto University, Kyoto, 606-8501, Japan.
authors.forename: Akihiko
authors.initials: A
authors.lastname: Ishihara
authors.affiliation: Laboratory of Cell Biology and Life Science, Graduate School of Human and Environmental Studies, Kyoto University, Kyoto, 606-8501, Japan.
authors.forename: Fumiko
authors.initials: F
authors.lastname: Nagatomo
authors.affiliation: Department of Cell Biology, Jikei University School of Medicine, Tokyo, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Terada
authors.affiliation: Department of Rehabilitation Science, Kobe University Graduate School of Health Sciences, Kobe, Japan.
authors.forename: Hidemi
authors.initials: H
authors.lastname: Fujino
authors.affiliation: Department of Food Sciences and Nutrition, Nagoya Women's University, Nagoya, Japan.
authors.forename: Hiroyo
authors.initials: H
authors.lastname: Kondo
authors.affiliation: Department of Interdisciplinary Science, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Japan.
authors.forename: Noriaki
authors.initials: N
authors.lastname: Ishioka
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D001835:Body Weight / Q000502:physiology; D005260:Female; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018482:Muscle, Skeletal / Q000033:anatomy & histology / Q000201:enzymology / Q000502:physiology*; D009929:Organ Size; D013385:Succinate Dehydrogenase / Q000145:classification / Q000378:metabolism; D014893:Weightlessness
chemical_list: D013385:Succinate Dehydrogenase; D000251:Adenosine Triphosphatases
keywords: fiber cross-sectional area; fiber oxidative staining intensity; forelimb muscle; muscle oxidative enzyme activity; spaceflight