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. Pro-inflammatory 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 males (age 27±4 yrs, body mass 77.5±9.0 kg, height 179±6 cm) performed four passive exposures to different normobaric hypoxic severities [FiO 2:0.209 (SL), FiO2:~0.135 (3,600 m), FiO2:~0.125 (4,200 m) and FiO2:~0.115 (4,800 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 erythropoietin concentration ([EPO]), IL-6 and TNFα. During 4,200 m and 4,800 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 4h (2h 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 ≥4,200 m. There was no dose-response relationship in [EPO] between simulated hypoxia severities.
|Number of pages||10|
|Journal||Scandinavian Journal of Medicine and Science in Sports|
|Publication status||Published - 17 May 2016|
Bibliographical noteThis is the peer reviewed version of the following article: Turner, G., Gibson, O. R., Watt, P. W., Pringle, J. S. M., Richardson, A. J. and Maxwell, N. S. (2016), The time course of endogenous erythropoietin, IL-6, and TNFα in response to acute hypoxic exposures. Scandinavian Journal of Medicine & Science in Sports, which has been published in final form at http://onlinelibrary.wiley.com/doi/10.1111/sms.12700/abstract?campaign=wolearlyview. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.