Cytoskeletal protein contents before and after hindlimb suspension in a fast and slow rat skeletal muscle.
Transversal cytoskeletal organization of muscle fibers is well described, although very few data are available concerning protein content. Measurements of desmin, alpha-actinin, and actin contents in soleus and extensor digitorum longus (EDL) rat skeletal muscles, taken with the results previously reported for several dystrophin-glycoprotein complex (DGC) components, indicate that the contents of most cytoskeletal proteins are higher in slow-type fibers than in fast ones. The effects of hypokinesia and unloading on the cytoskeleton were also investigated, using hindlimb suspension. First, this resulted in a decrease in contractile protein contents, only after 6 wk, in the soleus. Dystrophin and associated proteins were shown to be reduced for soleus at 3 wk, whereas only the dystrophin-associated proteins were found to increase after 6 wk. On the other hand, the contents of DGC components were increased for EDL for the two durations. Desmin and alpha-actinin levels were unchanged in the same conditions. Consequently, it can be concluded that the cytoskeletal protein expression levels could largely contribute to muscle fiber adaptation induced by modified functional demands.
Chopard
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Laboratoire de Physiologie Cellulaire et Moléculaire des Systèmes Intégrés, Centre National de la Recherche Scientifique Unité Mixte de Recherche 6548, Faculté des Sciences, 06108 Nice Cedex 2, France. achopard@unice.fr
Pons
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F
Marini
J F
JF
D000818:Animals; D001835:Body Weight; D003285:Contractile Proteins / Q000378:metabolism*; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D005260:Female; D019417:Hindlimb Suspension / Q000502:physiology*; D007150:Immunohistochemistry; D018656:Muscle Fibers, Fast-Twitch / Q000502:physiology*; D018657:Muscle Fibers, Slow-Twitch / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D018995:Myosin Heavy Chains / Q000378:metabolism*; D009929:Organ Size; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors
D003285:Contractile Proteins; D003598:Cytoskeletal Proteins; D018995:Myosin Heavy Chains