title: Acute and severe hypobaric hypoxia increases oxidative stress and impairs mitochondrial function in mouse skeletal muscle.
abstract: Severe high-altitude hypoxia exposure is considered a triggering stimulus for redox disturbances at distinct levels of cellular organization. The effect of an in vivo acute and severe hypobaric hypoxic insult (48 h at a pressure equivalent to 8,500 m) on oxidative damage and respiratory function was analyzed in skeletal muscle mitochondria isolated from vitamin E-supplemented (60 mg/kg ip, 3 times/wk for 3 wk) and nonsupplemented mice. Forty male mice were randomly divided into four groups: control + placebo, hypoxia + placebo (H + P), control + vitamin E, and hypoxia + vitamin E. Significant increases in mitochondrial heat shock protein 60 expression and protein carbonyls group levels and decreases in aconitase activity and sulfhydryl group content were found in the H + P group when compared with the control + placebo group. Mitochondrial respiration was significantly impaired in animals from the H + P group, as demonstrated by decreased state 3 respiratory control ratio and ADP-to-oxygen ratio and by increased state 4 with both complex I- and II-linked substrates. Using malate + pyruvate as substrates, hypoxia decreased the respiratory rate in the presence of carbonyl cyanide m-chlorophenylhydrazone and also stimulated oligomycin-inhibited respiration. However, vitamin E treatment attenuated the effect of hypoxia on the mitochondrial levels of heat shock protein 60 and markers of oxidative stress. Vitamin E was also able to prevent most mitochondrial alterations induced by hypobaric hypoxia. In conclusion, hypobaric hypoxia increases mitochondrial oxidative stress while decreasing mitochondrial capacity for oxidative phosphorylation. Vitamin E was an effective preventive agent, which further supports the oxidative character of mitochondrial dysfunction induced by hypoxia.
authors.affiliation: Department of Sport Biology, Faculty of Sport Science, Institute for Molecular and Cell Biology University of Porto, Portugal. jmaga@fcdef.up.pt
authors.forename: José
authors.initials: J
authors.lastname: Magalhães
authors.forename: António
authors.initials: A
authors.lastname: Ascensão
authors.forename: José M C
authors.initials: JM
authors.lastname: Soares
authors.forename: Rita
authors.initials: R
authors.lastname: Ferreira
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Neuparth
authors.forename: Franklim
authors.initials: F
authors.lastname: Marques
authors.forename: José A
authors.initials: JA
authors.lastname: Duarte
mesh_terms: D000208:Acute Disease; D000818:Animals; D001274:Atmospheric Pressure; D000860:Hypoxia / Q000209:etiology* / Q000378:metabolism / Q000503:physiopathology*; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D008931:Mitochondria, Muscle / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000378:metabolism*; D018384:Oxidative Stress; D010101:Oxygen Consumption / Q000187:drug effects; D012720:Severity of Illness Index; D013481:Superoxides / Q000378:metabolism; D014810:Vitamin E / Q000378:metabolism / Q000494:pharmacology
chemical_list: D013481:Superoxides; D014810:Vitamin E