title: Physiological, histological and biochemical properties of rat skeletal muscles in response to hindlimb suspension.
abstract: In previous study, we found that the reduced exercise-induced production of reactive oxygen species (ROS) reported in slow-oxidative muscle of hypoxemic rats and also in chronic hypoxemic patients did not simply result from deconditioning. In control rats and after a 3-week period of hindlimb suspension (HS), the slow-oxidative (Soleus, SOL) and fast-glycolytic skeletal muscles (Extensor digitorum longus, EDL) were sampled. We determined the response to direct muscle stimulation (twitch stimulation (TS), Maximal force (Fmax)), twitch amplitude and maximal relaxation rate, tetanic frequency, endurance to fatigue after muscle stimulation (MS), the different fibre types based on their myofibrillar adenosinetriphosphatase (ATPase) activity, and the intra-muscular redox status (Thiobarbituric Acid Reactive Sustances: TBARS, reduced glutathione: GSH, reduced ascorbic acid: RAA). After the 3-w HS period: (1) the contractile properties were modified in SOL only (reduced Fmax and twitch amplitude, increased tetanic frequency); (2) the fibre typology was modified in both muscles (in SOL: increased proportion of IIa and IIc fibres, in EDL: increased proportion of IId/x fibres but decreased proportion of IIb fibres); and (3) only in SOL, the TBARS level increased and the GSH and RAA concentrations decreased at rest and after fatiguing MS. Thus, HS accentuates the exercise-induced ROS production in slow-oxidative muscle in a direction opposite to that measured in chronic hypoxemic rats. This strongly suggests that hypoxemia reduces the ROS production independently from any muscle disuse.
authors.affiliation: Laboratoire de Physiopathologie Respiratoire EA 2201, Institut Jean Roche, Faculté de Médecine Nord, Bd. Pierre Dramard, 13916 Marseille, France.
authors.forename: Chantal
authors.initials: C
authors.lastname: Guillot
authors.forename: Jean Guillaume
authors.initials: JG
authors.lastname: Steinberg
authors.forename: Stephane
authors.initials: S
authors.lastname: Delliaux
authors.forename: Nathalie
authors.initials: N
authors.lastname: Kipson
authors.forename: Yves
authors.initials: Y
authors.lastname: Jammes
authors.forename: Monique
authors.initials: M
authors.lastname: Badier
mesh_terms: D000818:Animals; D001205:Ascorbic Acid / Q000032:analysis; D005978:Glutathione / Q000032:analysis; D006614:Hindlimb; D019417:Hindlimb Suspension / Q000502:physiology*; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction; D018485:Muscle Fibers, Skeletal / Q000145:classification; D018482:Muscle, Skeletal / Q000033:anatomy & histology / Q000378:metabolism / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism
chemical_list: D017392:Thiobarbituric Acid Reactive Substances; D005978:Glutathione; D001205:Ascorbic Acid