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Human fiber size and enzymatic properties after 5 and 11 days of spaceflight
Abstract
Biopsies from the vastus lateralis muscle were obtained from three astronauts before and after two 5-day flights and from five astronauts before and after one 11-day flight (space shuttle flights: STS-32, -33, and -34). Muscle fibers from two separate samples from each biopsy were classified as type I and II or as type I, IIA, and IIB by using qualitative myofibrillar adenosinetriphosphatase (ATPase) staining. Cross-sectional area (CSA), number of capillaries per fiber, and the activities of succinate dehydrogenase (SDH), alpha-glycerophosphate dehydrogenase (GPD), and myofibrillar ATPase were determined from one sample of fibers of each myofibrillar ATPase type. Postflight biopsies had 6-8% fewer type I fibers than preflight. Mean fiber CSAs were 16-36% smaller after the 11-day flight with the relative effect being type IIB > IIA > I. Mean fiber CSAs were 11 and 24% smaller in type I and II fibers after 5 days of flight. Myofibrillar ATPase activities increased in type II but not in type I fibers after flight, whereas SDH activity was unaffected in either fast or slow fibers. GPD activity in type I fibers was approximately 80% higher (P > 0.05) postflight compared with preflight. Myofibrillar ATPase/SDH ratios in type II fibers were higher after than before flight, suggesting that some fast fibers were more susceptible to fatigue after flight. The GPD/SDH ratios were elevated in some type I fibers after spaceflight. The number of capillaries per fiber was 24% lower after tha…
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“This finding is in general agreement with clinical (75) and spaceflight induced atrophy, which was reported by Edgerton et al. (76) and LeBlanc et al. (77) but is in contrast to Mulder et al. (5), who demonstrated linear decline of quadriceps femoris CSA during 56 days of bed rest.”
From Nonuniform loss of muscle strength and atrophy during bed rest: a systematic review (2021) · cites this paper as [76]
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Metadata
- Authors
- Edgerton, V. R., Zhou, M. Y., Ohira, Y., Klitgaard, H., Jiang, B., Bell, G., Harris, B., Saltin, B., Gollnick, P. D., Roy, R. R., & et, A.
- Affiliations
- University of California, Los Angeles (US)
- Venue
- Journal of Applied Physiology
- Publisher
- American Physiological Society
- Published
- 1995-05-01
- Volume
- 78
- Issue
- 5
- Pages
- 1733-1739
- ISSN
- 0161-7567 (ISSN-L)
- 8750-7587
- 1522-1601
- OpenAlex
- W1843900867
- Cited by
- 324
- References
- 0
- Citations by year
- 2026: 8 · 2025: 16 · 2024: 7 · 2023: 10 · 2022: 12 · 2021: 14 · 2020: 5 · 2019: 9 · 2018: 5 · 2017: 7 · 2016: 13 · 2015: 11 · 2014: 12 · 2013: 8 · 2012: 3
- FWCI
- 3.09
- Type
- journal article
- Language
- en
- Open access
- closed
- Locations
- Journal of Applied Physiology (publishedVersion)
- PubMed (publishedVersion)
- Research at the University of Copenhagen (University of Copenhagen) (submittedVersion)
- Topics
- Health Sciences › Medicine › Physiology (medical) › Spaceflight effects on biology
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Muscle Physiology and Disorders
- Physical Sciences › Engineering › Aerospace Engineering › Space Exploration and Technology
- Keywords
- spaceflight, muscle fiber size, vastus lateralis, muscle fiber type, myofibrillar ATPase, succinate dehydrogenase, alpha-glycerophosphate dehydrogenase, capillary density, muscle fiber cross-sectional area, muscle fatigue, muscle metabolism, astronauts, microgravity adaptation
- MeSH terms
- Adenosine Triphosphatases, Adult, Capillaries, Female, Glucosephosphate Dehydrogenase, Humans, Male, Middle Aged, Myofibrils, Space Flight, Succinate Dehydrogenase, Time Factors, Muscle, Skeletal, Muscle Fibers, Skeletal, Muscle Fatigue
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