title: Plasma glutathione peroxidase activity as a potential indicator of hypoxic stress in breath-hold diving.
abstract: BACKGROUND
  Diving mammals can cope with oxidants which are produced in excess during the reoxygenation of hypoxic tissues. This study addresses the question of whether antioxidants can adapt and whether it allows humans to tolerate the hypoxic stress induced by a single breath-holding in the course of a dynamic diving exercise and protect them from oxidative insult.
  
  
  METHODS
  There were 20 male subjects who performed submaximal apnea dynamic diving (ADD). Nine control subjects stayed out of the water and breathed normally. Venous blood samples were collected 1 h before and immediatly after ADD.
  
  
  RESULTS
  ADD induced a significant increase in plasma glutathione peroxidase (GPx-3) activity (from 397.5 +/- 44.4 to 410 +/- 43 U x L(-1)), blood reduced glutathione (GSH) (from 1060 +/- 302 to 1292 +/- 213 micromol x L(-1)), and in plasma creatine kinase activity (from 215 +/- 137 to 235 +/- 152 U x L(-1)). The activity of the erythrocyte superoxide dismutase and glutathione peroxidase, as well as the blood oxidized glutathione and the plasma thiobarbituric acid reactive substances concentrations, were maintained at their basal level. The level of training, characterized by the duration and distance of the dive, had no effect on the markers used.
  
  
  CONCLUSIONS
  GPx-3 and GSH could constitute the most readily mobilizable antioxidants that would then contribute to the buffering against a sudden increase in the generation of radical oxygen species. These biomarkers could be used as tools for establishing oxidative stress during hypoxia. The response of GPx-3 to hypoxia could be of physiological relevance.
authors.affiliation: Laboratoire Physiologie des Adaptations, Performances Motrices et Santé (EA 3837), Université de Nice-Sophia-Antipolis, Faculté des Sciences du Sport, 261 route de Grenoble, BP 3259, 06205 Nice 3, France. asrousse@unice.fr
authors.forename: Anne-Sophie
authors.initials: AS
authors.lastname: Rousseau
authors.forename: Caroline
authors.initials: C
authors.lastname: Richer
authors.forename: Marie-Jeanne
authors.initials: MJ
authors.lastname: Richard
authors.forename: Alain
authors.initials: A
authors.lastname: Favier
authors.forename: Irène
authors.initials: I
authors.lastname: Margaritis
mesh_terms: D000328:Adult; D001049:Apnea; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D004242:Diving; D005978:Glutathione / Q000097:blood; D005979:Glutathione Peroxidase / Q000097:blood*; D006801:Humans; D000860:Hypoxia / Q000097:blood*; D008297:Male; D018384:Oxidative Stress
chemical_list: D015415:Biomarkers; D005979:Glutathione Peroxidase; D005978:Glutathione