title: The time course of endogenous erythropoietin, IL-6, and TNFα in response to acute hypoxic exposures.
abstract: Erythropoietin (EPO) rapidly decreases on return to sea level (SL) after chronic altitude exposure. Acute hypoxia may provide an additional stimulus to prevent the decline in EPO. Proinflammatory cytokines, interleukin-6 (IL-6), and tumor necrosis factor alpha (TNFα) have been shown to inhibit EPO production. Optimal normobaric hypoxic exposure has not been established; therefore, investigation of methods eliciting the greatest response in EPO to limit physiological stress is required. Eight men (age 27 ± 4 years, body mass 77.5 ± 9.0 kg, height 179 ± 6 cm) performed four passive exposures to different normobaric hypoxic severities [FiO2: 0.209 (SL), FiO2: ~0.135 (3600 m), FiO2: ~0.125 (4200 m) and FiO2: ~0.115 (4800 m)] in a hypoxic chamber for 2 h. Venous blood was drawn pre-exposure and then at 1, 2, 4, 6, and 8 h to determine EPO concentration ([EPO]), IL-6, and TNFα. During 4200 and 4800 m, [EPO] increased from 5.9 ± 1.5 to 8.1 ± 1.5 mU/mL (P = 0.009) and 6.0 ± 1.4 to 8.9 ± 2.0 mU/mL (P = 0.037), respectively, with [EPO] increase peaking at 4 h (2 h post-exposure). There were no differences in IL-6 or TNFα during or post-exposure. Increased [EPO] was found 2 h post hypoxic exposure as result of 2 h of normobaric hypoxia ≥4200 m. There was no dose-response relationship in [EPO] between simulated hypoxia severities.
authors.affiliation: Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Eastbourne, UK.|English Institute of Sport, EIS Performance Centre, Loughborough University, Loughborough, UK.
authors.forename: G
authors.initials: G
authors.lastname: Turner
authors.affiliation: Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Eastbourne, UK.
authors.forename: O R
authors.initials: OR
authors.lastname: Gibson
authors.affiliation: Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Eastbourne, UK.
authors.forename: P W
authors.initials: PW
authors.lastname: Watt
authors.affiliation: English Institute of Sport, EIS Performance Centre, Loughborough University, Loughborough, UK.
authors.forename: J S M
authors.initials: JSM
authors.lastname: Pringle
authors.affiliation: Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Eastbourne, UK.
authors.forename: A J
authors.initials: AJ
authors.lastname: Richardson
authors.affiliation: Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Eastbourne, UK.
authors.forename: N S
authors.initials: NS
authors.lastname: Maxwell
mesh_terms: D000328:Adult; D000531:Altitude; D004921:Erythropoietin / Q000097:blood*; D006801:Humans; D000860:Hypoxia / Q000097:blood*; D015850:Interleukin-6 / Q000097:blood*; D008297:Male; D016037:Single-Blind Method; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000097:blood*; D055815:Young Adult
chemical_list: C554270:EPO protein, human; C508600:IL6 protein, human; D015850:Interleukin-6; D014409:Tumor Necrosis Factor-alpha; D004921:Erythropoietin
keywords: 
  EPO
  ; Hypoxia; altitude; cytokines; inflammation