Independently, both inactivity and hypoxia augment oxidative stress. This study, part of the FemHab project, investigated the combined effects of bed rest-induced unloading and hypoxic exposure on oxidative stress and antioxidant status. Healthy, eumenorrheic females were randomly assigned to the following three, 10-day experimental interventions: normoxic bed rest (NBR;n=11;PiO2=133mmHg); normobaric hypoxic bed rest (HBR;n=12;PiO2=90mmHg) and ambulatory hypoxic confinement (HAMB;n=8;PiO2=90mmHg). Plasma samples, obtained before (Pre), during (D2,D6), immediately after (Post) and 24-hrs after (Post+1) each intervention, were analyzed for oxidative stress markers [advanced oxidation protein products (AOPP), malondialdehyde (MDA) and nitrotyrosine], antioxidant status [superoxide dismutase (SOD), catalase, ferric-reducing antioxidant power (FRAP), glutathione peroxidase (GPX) and uric acid (UA)], NO metabolism end-products (NOx) and nitrites. Compared to baseline, AOPP increased in NBR and HBR on D2 (+14%;+12%;P<0.05), D6 (+19%;+15%;P<0.05) and Post (+22%;+21%;P<0.05), respectively. MDA increased at Post+1 in NBR (+116%;P<0.01) and D2 in HBR (+114%;P<0.01) and HAMB (+95%;P<0.05). Nitrotyrosine decreased (-45%;P<0.05) and nitrites increased (+46%;P<0.05) at Post+1 in HAMB only. While SOD was higher at D6 (+82%) and Post+1 (+67%) in HAMB only, the catalase activity increased on D6 (128%) and Post (146%) in HBR and HAMB, respectively (P<0.05). GPX was only reduced on D6(-20%;P<0.01) and Post(-18%;P<0.05) in HBR. No differences were observed in FRAP and NOx. UA was higher at Post in HBR compared to HAMB (P<0.05). These data indicate that exposure to combined inactivity and hypoxia impairs prooxidant/antioxidant balance in healthy females. Moreover, habitual activity levels, as opposed to inactivity, seem to blunt hypoxia-related oxidative stress via antioxidant system up-regulation.
- nitrosative stress
- normobaric hypoxia
- Copyright © 2015, Journal of Applied Physiology