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Cytoplasm-to-myonucleus ratios following microgravity
1Jerry Lewis Neuromuscular Research Center, University of California, Los Angeles 90095-6918, USA.
Journal of Muscle Research and Cell Motility
|October 1, 1996
Summary
Short-term microgravity or hindlimb suspension significantly decreases the cytoplasmic volume-to-myonucleus ratio in rat leg muscles. This occurs due to reduced muscle fiber size and increased myonuclei number, impacting muscle cell regulation.
Area of Science:
- Space biology
- Skeletal muscle physiology
- Cellular biology
Background:
- Microgravity and hindlimb suspension induce muscle atrophy.
- The cytoplasmic volume-to-myonucleus ratio is a critical factor in muscle cell function and adaptation.
Purpose of the Study:
- To investigate the effects of short-term microgravity and hindlimb suspension on the cytoplasmic volume-to-myonucleus ratio in rat skeletal muscles.
- To analyze changes in muscle fiber cross-sectional area and myonuclei number.
Main Methods:
- Single fiber analysis of tibialis anterior and gastrocnemius muscles.
- Comparison between space-flown rats, hindlimb-suspended rats, and ground controls.
Main Results:
- Microgravity and suspension decreased muscle fiber cross-sectional area.
- Myonuclei number increased in microgravity but not in suspension.
- Significant decrease in cytoplasmic volume-to-myonucleus ratio observed in both space and suspended rats.
Conclusions:
- Short-term unweighting significantly alters skeletal muscle fiber characteristics.
- The cytoplasmic volume-to-myonucleus ratio is sensitive to microgravity and suspension, indicating cellular adaptation.
- These findings have implications for understanding muscle adaptation in space and during immobility.