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Contractile properties and myosin expression in rats born and reared in hypergravity
1Laboratoire de Plasticité Neuromusculaire, Université des Sciences et Technologies de Lille, 59655 Villeneuve d'Ascq Cedex, France. Florence.Picquet@univ-lille1.fr
Summary
Hypergravity (HG) exposure slows rat growth and alters muscle composition. Muscles adapt to HG conditions, showing changes in fiber type and contractile properties, indicating significant muscular plasticity.
Area of Science:
- Muscle physiology
- Gravitational biology
- Animal models
Background:
- Understanding skeletal muscle adaptation is crucial for space exploration and terrestrial conditions involving altered gravity.
- Previous research indicates that microgravity affects muscle mass and function, but the effects of sustained hypergravity are less understood.
Purpose of the Study:
- To investigate the impact of chronic hypergravity (2g) on the morphological and contractile properties of soleus and plantaris muscles in rats.
- To analyze changes in myosin heavy chain (MHC) isoforms in response to a hypergravity environment.
Main Methods:
- Long Evans rats were reared under 2g conditions (hypergravity group) and compared to age-paired terrestrial controls.
- Morphological analysis, contractile property measurements, and myosin heavy chain (MHC) content analysis were performed on soleus and plantaris muscles.
Main Results:
- Hypergravity slowed overall rat growth and reduced absolute muscle weight.
- Soleus muscle exhibited a shift towards slower contractile properties and exclusively MHC I isoform expression.
- Plantaris muscle displayed faster contractile behavior and an increased diversity of hybrid fiber types expressing multiple MHC isoforms (MHC IIB, MHC IIX).
Conclusions:
- The hypergravity environment induces significant muscular plasticity in both slow (soleus) and fast (plantaris) muscle types.
- These findings highlight the adaptive capacity of skeletal muscle to altered gravitational forces, with implications for understanding muscle adaptation in various environments.