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Changes in contractile protein mRNA accumulation in response to spaceflight
1Muscle Development Unit, Children's Medical Research Institute, Wentworthville, New South Wales, Australia.
The American Journal of Physiology
|February 1, 1995
Summary
Spaceflight alters muscle gene expression. Zero gravity increased fast muscle gene s in both fast and slow muscles, while slow genes showed varied changes in the soleus muscle.
Area of Science:
- Space biology
- Molecular biology
- Muscle physiology
Background:
- Muscle atrophy and functional changes occur during spaceflight.
- Understanding molecular adaptations is crucial for astronaut health.
Purpose of the Study:
- To investigate the effects of short-term spaceflight on contractile protein gene expression in rat hindlimb muscles.
- To quantify changes in fast and slow mRNA isoforms in response to microgravity.
Main Methods:
- Ten rats were flown on the NASA SLS-1 mission for 9 days.
- mRNA levels of six contractile protein gene families (myosin, troponin, tropomyosin) were measured in soleus and EDL muscles.
- Quantitative analysis of fast and slow mRNA isoforms.
Main Results:
- In the extensor digitorum longus (EDL) muscle, slow mRNA levels remained unchanged, while fast mRNA levels increased significantly (23-232%).
- In the soleus muscle, fast mRNA levels showed a substantial increase (170-1100%).
- Soleus slow mRNA levels exhibited mixed changes: slight increases in troponin C and T, but decreases in myosin light chains, troponin I, and tropomyosin.
Conclusions:
- Zero gravity exposure induces a general upregulation of fast muscle gene expression in both fast (EDL) and slow (soleus) muscles.
- Microgravity causes differential regulation of slow muscle gene expression in the soleus, with some genes decreasing and others slightly increasing.