RT Journal Article SR Electronic T1 Effects of intermittent hypoxia on Epo, soluble Epo receptor and ventilation in humans JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society SP erj01560-2009 DO 10.1183/09031936.00156009 A1 J.V. Brugniaux A1 V. Pialoux A1 G.E. Foster A1 C.T.C. Duggan A1 M. Eliasziw A1 P.J. Hanly A1 M.J. Poulin YR 2010 UL http://erj.ersjournals.com/content/early/2010/10/14/09031936.00156009.abstract AB Erythropoietin (Epo) and soluble Epo receptors (sEpoR) have been proposed to play a central role in the ventilatory acclimatization to continuous hypoxia in mice.In this study, we demonstrated for the first time in humans (n=9) that sEpoR is downregulated upon daytime exposure to 4 days of intermittent hypoxia (IH) [6h/day; cycles of 2-min of hypoxia followed by 2-min of reoxygenation - peak end-tidal PO2 (Peto2) =88 Torr; nadir Peto2 =45 Torr], thereby allowing Epo concentration to rise. We also determined the strength of the association between these hematological adaptations and alterations in the acute hypoxic ventilatory response (AHVR).We observed a nadir in sEpoR on Day 2 (−70%), concomitant with the peak in Epo concentration (+50%). Following exposure to IH, tidal volume (VT) increased, breathing frequency (fR) remained unchanged, and overall ventilation (VE) was increased. There was a negative correlation between Epo and sEpoR (r=−0.261, p=0.05), and between sEpoR and VT (r=−0.331, p=0.02). Epo was positively correlated with VE (r=0.458, p=0.001).In conclusion, the downregulation of sEpoR by IH modulates the subsequent Epo response. Furthermore, the alterations in AHVR and breathing pattern following IH appear to be mediated, at least in part, by the increase in Epo.