title: Changes in mitochondrial enzymatic activities of monocytes during prolonged hypobaric hypoxia and influence of antioxidants: A randomized controlled study.
abstract: OBJECTIVE
  Exposure to high altitudes is associated with oxidative cellular damage due to the increased level of reactive oxygen and nitrogen species and altered activity of antioxidant systems. Subjects were submitted to prolonged hypoxia, to evaluate changes in mitochondrial enzyme activities of monocytes and their attenuation by supplementation with antioxidants.
  
  
  METHODS
  Twelve subjects were randomly assigned to receive antioxidant supplements or placebo prior to and during an expedition to Pik Lenin (7145 m). Monocytes were isolated from blood samples to determine the activity of mitochondrial enzymes cytochrome c oxidase and citrate synthase at 490 m (baseline) and at the altitudes of 3550 m, 4590 m, and 5530 m.
  
  
  RESULTS
  An increase in citrate synthase activity at all altitudes levels was observed. Hypoxia induced an increase in the activity of cytochrome c oxidase only at 4590 m. Neither citrate synthase activity nor cytochrome c oxidase activity differed between the subjects receiving antioxidant supplements and those receiving placebo.
  
  
  CONCLUSIONS
  Hypoxia leads to an increase in citrate synthase activity of monocyte mitochondria as a marker of mitochondrial mass, which is not modified by antioxidant supplementation. The increase in mitochondrial mass may represent a compensatory mechanism to preserve oxidative phosphorylation of monocytes at high altitudes.
authors: Tobias M
authors: TM
authors: Merz
authors: Jacqueline
authors: J
authors: Pichler Hefti
authors: Urs
authors: U
authors: Hefti
authors: Andreas
authors: A
authors: Huber
authors: Stephan M
authors: SM
authors: Jakob
authors: Jukka
authors: J
authors: Takala
authors: Siamak
authors: S
authors: Djafarzadeh
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000975:Antioxidants / Q000627:therapeutic use*; D001274:Atmospheric Pressure; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000188:drug therapy* / Q000201:enzymology* / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects; D008297:Male; D008875:Middle Aged; D008928:Mitochondria / Q000201:enzymology*; D009000:Monocytes / Q000201:enzymology*; D018384:Oxidative Stress / Q000187:drug effects; D055815:Young Adult
chemical_list: D000975:Antioxidants
keywords: Antioxidants; Mitochondrial function; Mitochondrial mass; Oxidative stress; Peripheral blood monocytes