title: Slow- and fast-twitch hindlimb skeletal muscle phenotypes 12 wk after ⅚ nephrectomy in Wistar rats of both sexes.
abstract: This study describes fiber-type adaptations in hindlimb muscles, the interaction of sex, and the role of hypoxia on this response in 12-wk ⅚ nephrectomized rats (Nx). Contractile, metabolic, and morphological features of muscle fiber types were assessed in the slow-twitch soleus and the fast-twitch tibialis cranialis muscles of Nx rats, and compared with sham-operated controls. Rats of both sexes were considered in both groups. A slow-to-fast fiber-type transformation occurred in the tibialis cranialis of Nx rats, particularly in males. This adaptation was accomplished by impaired oxidative capacity and capillarity, increased glycolytic capacity, and no changes in size and nuclear density of muscle fiber types. An oxidative-to-glycolytic metabolic transformation was also found in the soleus muscle of Nx rats. However, a modest fast-to-slow fiber-type transformation, fiber hypertrophy, and nuclear proliferation were observed in soleus muscle fibers of male, but not of female, Nx rats. Serum testosterone levels decreased by 50% in male but not in female Nx rats. Hypoxia-inducible factor-1α protein level decreased by 42% in the tibialis cranialis muscle of male Nx rats. These data demonstrate that 12 wk of Nx induces a muscle-specific adaptive response in which myofibers do not change (or enlarge minimally) in size and nuclear density, but acquire markedly different contractile and metabolic characteristics, which are accompanied by capillary rarefaction. Muscle function and sex play relevant roles in these adaptations.
authors.affiliation: Laboratory of Muscular Biopathology, Department of Comparative Anatomy and Pathological Anatomy, Faculty of Veterinary Sciences, University of Cordoba, Cordoba, Spain; Departamento de Ciencias Biomédicas, Facultad de Ciencias Veterinarias, Universidad Central de Venezuela, Maracay, Venezuela;
authors.forename: Luz M
authors.initials: LM
authors.lastname: Acevedo
authors.affiliation: Departament of Animal Medicine and Surgery, University of Cordoba, Spain; Escuela de Medicina Veterinaria, Universidad Nacional Autónoma de Nicaragua, León, Nicaragua; and.
authors.forename: Alan
authors.initials: A
authors.lastname: Peralta-Ramírez
authors.affiliation: Departament of Animal Medicine and Surgery, University of Cordoba, Spain;
authors.forename: Ignacio
authors.initials: I
authors.lastname: López
authors.affiliation: Laboratory of Muscular Biopathology, Department of Comparative Anatomy and Pathological Anatomy, Faculty of Veterinary Sciences, University of Cordoba, Cordoba, Spain;
authors.forename: Verónica E
authors.initials: VE
authors.lastname: Chamizo
authors.affiliation: Departament of Animal Medicine and Surgery, University of Cordoba, Spain;
authors.forename: Carmen
authors.initials: C
authors.lastname: Pineda
authors.affiliation: Laboratory of Nephrology, IIS-Fundación Jiménez Díaz (Red in Ren), Madrid, Spain.
authors.forename: Maria E
authors.initials: ME
authors.lastname: Rodríguez-Ortiz
authors.affiliation: Unidad de Investigación y Servicio de Nefrología (Red in Ren), Instituto Sanitario de Investigación Biomédica de Córdoba (IMIBIC), Reina Sofia University Hospital, University of Cordoba, Spain;
authors.forename: Mariano
authors.initials: M
authors.lastname: Rodríguez
authors.affiliation: Departament of Animal Medicine and Surgery, University of Cordoba, Spain;
authors.forename: Escolástico
authors.initials: E
authors.lastname: Aguilera-Tejero
authors.affiliation: Laboratory of Muscular Biopathology, Department of Comparative Anatomy and Pathological Anatomy, Faculty of Veterinary Sciences, University of Cordoba, Cordoba, Spain; an1lorij@uco.es.
authors.forename: José-Luis L
authors.initials: JL
authors.lastname: Rivero
mesh_terms: D000818:Animals; D001835:Body Weight / Q000502:physiology; D002196:Capillaries / Q000166:cytology / Q000502:physiology; D004435:Eating / Q000502:physiology; D005260:Female; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000378:metabolism; D006614:Hindlimb / Q000166:cytology* / Q000502:physiology*; D000860:Hypoxia / Q000473:pathology; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism; D007677:Kidney Function Tests; D008297:Male; D018656:Muscle Fibers, Fast-Twitch / Q000502:physiology* / Q000648:ultrastructure; D018657:Muscle Fibers, Slow-Twitch / Q000502:physiology* / Q000648:ultrastructure; D018995:Myosin Heavy Chains / Q000378:metabolism; D009392:Nephrectomy; D009929:Organ Size / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D012727:Sex Characteristics; D013385:Succinate Dehydrogenase / Q000378:metabolism; D013739:Testosterone / Q000378:metabolism; D014511:Uremia / Q000473:pathology
chemical_list: C497444:Hif1a protein, rat; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D013739:Testosterone; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases; D013385:Succinate Dehydrogenase; D018995:Myosin Heavy Chains
keywords: chronic renal failure; gonadal hormones; hypoxia-inducible factor-1α; muscle plasticity; myosin heavy chain; uremia