Open AccessPlanHab: Hypoxia counteracts the erythropoietin suppression, but seems to exaggerate the plasma volume reduction induced by 3 weeks of bed rest
Author(s) -
Keramidas Michail E.,
Mekjavic Igor B.,
Kölegård Roger,
Choukèr Alexander,
Strewe Claudia,
Eiken Ola
Publication year - 2016
Publication title -
physiological reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.918
H-Index - 39
ISSN - 2051-817X
DOI - 10.14814/phy2.12760
Subject(s) - erythropoietin , hematocrit , bed rest , hypoxia (environmental) , plasma volume , medicine , endocrinology , chemistry , hemoglobin , intermittent hypoxia , oxygen , organic chemistry , obstructive sleep apnea
The study examined the distinct and synergistic effects of hypoxia and bed rest on the erythropoietin ( EPO ) concentration and relative changes in plasma volume ( PV ). Eleven healthy male lowlanders underwent three 21‐day confinement periods, in a counterbalanced order: (1) normoxic bed rest ( NBR ; P I O 2 : 133.1 ± 0.3 mmHg); (2) hypoxic bed rest ( HBR ; P I O 2 : 90.0 ± 0.4 mmHg, ambient simulated altitude of ~4000 m); and (3) hypoxic ambulation ( HAMB ; P I O 2 : 90.0 ± 0.4 mmHg). Blood samples were collected before, during (days 2, 5, 14, and 21) and 2 days after each confinement to determine EPO concentration. Qualitative differences in PV changes were also estimated by changes in hematocrit and hemoglobin concentration along with concomitant changes in plasma renin concentration. NBR caused an initial reduction in EPO by ~39% ( P = 0.04). By contrast, HBR enhanced EPO ( P = 0.001), but the increase was less than that induced by HAMB ( P < 0.01). All three confinements caused a significant reduction in PV ( P < 0.05), with a substantially greater drop in HBR than in the other conditions ( P < 0.001). Thus, present results suggest that hypoxia prevents the EPO suppression, whereas it seems to exaggerate the PV reduction induced by bed rest.