Akihiko Ishihara1, Fumiko Nagatomo1, Masahiro Terada2, Hidemi Fujino3, Hiroyo Kondo4, Noriaki Ishioka5. 1. Laboratory of Cell Biology and Life Science, Graduate School of Human and Environmental Studies, Kyoto University, Kyoto, 606-8501, Japan. 2. Department of Cell Biology, Jikei University School of Medicine, Tokyo, Japan. 3. Department of Rehabilitation Science, Kobe University Graduate School of Health Sciences, Kobe, Japan. 4. Department of Food Sciences and Nutrition, Nagoya Women's University, Nagoya, Japan. 5. Department of Interdisciplinary Science, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Japan.
Abstract
INTRODUCTION: 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.
INTRODUCTION: 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.