title: Expression of Myosin heavy chain isoforms in rat soleus muscle spindles after 19 days of hypergravity.
abstract: The aim of this study was to determine whether a period of 19 days in hypergravity was long enough to induce changes in the expression of myosin heavy chain (MyHC) isoforms in the muscle spindles. The soleus muscle of 10 male Wistar rats (control: CONT, n=5; hypergravity: HG, n=5) was frozen, cut into serial sections, and labeled with antibodies against MyHCs: I, IIA, IIA + IIX + IIB, slow-tonic, and alpha-cardiac. Forty CONT and 45 HG spindles were analyzed. The results from HG spindles compared to CONT showed that there was no change in the cross-sectional area of intrafusal fibers. However, along the entire length of B1 fibers, the expression of both MyHC I and alpha-cardiac was increased significantly, whereas the labeling against MyHC IIA and MyHC slow-tonic was decreased. In B2 fibers, the labeling against MyHC IIA (region A), slow-tonic (region A), and fast myosins (regions A-C) was statistically decreased. In chain fibers, the labeling against both MyHC IIA and fast MyHC was reduced significantly. We conclude that hypergravity has a real impact on the MyHC content in the muscle spindles and induces some inverse changes of those observed in hypogravity for MyHCs I, alpha-cardiac, and slow-tonic.
authors.affiliation: Laboratoire de Plasticité Neuromusculaire, EA 1032, IFR 118, Université des Sciences et Technologies de Lille, Bâtiment SN4, 59655 Villeneuve d'Ascq Cedex, France. Florence.Picquet@univ-lille1.fr
authors.forename: Florence
authors.initials: F
authors.lastname: Picquet
authors.forename: Laurent
authors.initials: L
authors.lastname: De-Doncker
authors.forename: Maurice
authors.initials: M
authors.lastname: Falempin
mesh_terms: D000818:Animals; D001835:Body Weight; D003720:Densitometry; D018471:Hypergravity; D007150:Immunohistochemistry; D008297:Male; D009470:Muscle Spindles / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000378:metabolism*; D018995:Myosin Heavy Chains / Q000096:biosynthesis*; D009929:Organ Size; D020033:Protein Isoforms / Q000096:biosynthesis; D051381:Rats; D017208:Rats, Wistar; D014463:Ultrasonography; D014893:Weightlessness
chemical_list: D020033:Protein Isoforms; D018995:Myosin Heavy Chains