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Separate and combined effects of a 10-d exposure to hypoxia and inactivity on oxidative function in vivo and mitochondrial respiration ex vivo in humans

Salvadego, D. and Keramidas, M.E. and Brocca, L. and Domenis, R. and Mavelli, I. and Rittweger, J. and Eiken, O. and Mekjavic, I. and Grassi, B. (2016) Separate and combined effects of a 10-d exposure to hypoxia and inactivity on oxidative function in vivo and mitochondrial respiration ex vivo in humans. Journal of Applied Physiology, 121 (1), pp. 154-163. American Physiological Society. DOI: 10.1152/japplphysiol.00832.2015 ISSN 8750-7587

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Abstract

An integrative evaluation of oxidative metabolism was carried out in 9 healthy young men (age, 24.1 ± 1.7 yr mean ± SD) before (CTRL) and after a 10-day horizontal bed rest carried out in normoxia (N-BR) or hypoxia (H-BR, FiO2 = 0.147). H-BR was designed to simulate planetary habitats. Pulmonary O2 uptake (V̇o2) and vastus lateralis fractional O2 extraction (changes in deoxygenated hemoglobin+myoglobin concentration, Δ[deoxy(Hb+Mb)] evaluated using near-infrared spectroscopy) were evaluated in normoxia and during an incremental cycle ergometer (CE) and one-leg knee extension (KE) exercise (aimed at reducing cardiovascular constraints to oxidative function). Mitochondrial respiration was evaluated ex vivo by high-resolution respirometry in permeabilized vastus lateralis fibers. During CE V̇o2peak and Δ[deoxy(Hb+Mb)]peak were lower (P < 0.05) after both N-BR and H-BR than during CTRL; during KE the variables were lower after N-BR but not after H-BR. During CE the overshoot of Δ[deoxy(Hb+Mb)] during constant work rate exercise was greater in N-BR and H-BR than CTRL, whereas during KE a significant difference vs. CTRL was observed only after N-BR. Maximal mitochondrial respiration determined ex vivo was not affected by either intervention. In N-BR, a significant impairment of oxidative metabolism occurred downstream of central cardiovascular O2 delivery and upstream of mitochondrial function, possibly at the level of the intramuscular matching between O2 supply and utilization and peripheral O2 diffusion. Superposition of hypoxia on bed rest did not aggravate, and partially reversed, the impairment of muscle oxidative function in vivo induced by bed rest. The effects of longer exposures will have to be determined.

Item URL in elib:https://elib.dlr.de/107448/
Document Type:Article
Title:Separate and combined effects of a 10-d exposure to hypoxia and inactivity on oxidative function in vivo and mitochondrial respiration ex vivo in humans
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Salvadego, D.University of UdineUNSPECIFIED
Keramidas, M.E.Swedish Aerospace Physiology Centre, Royal Institute of Technology, Stockholm, SwedenUNSPECIFIED
Brocca, L.luca.brocca (at) irpi.cnr.itUNSPECIFIED
Domenis, R.University of UdineUNSPECIFIED
Mavelli, I.University of UdineUNSPECIFIED
Rittweger, J.Institute of Aerospace Medicine, Deutsches Zentrum für Luft- und Raumfahrt, DLR e.V., Cologne, Germany and Medical Faculty, University of Cologne, Cologne, Germany; joern.rittweger (at) dlr.deUNSPECIFIED
Eiken, O.Swedish Aerospace Physiology Centre, Royal Institute of Technology, Stockholm, SwedenUNSPECIFIED
Mekjavic, I.Jozef Stefan InstituteUNSPECIFIED
Grassi, B.University of Udine, ItalyUNSPECIFIED
Date:July 2016
Journal or Publication Title:Journal of Applied Physiology
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:121
DOI :10.1152/japplphysiol.00832.2015
Page Range:pp. 154-163
Editors:
EditorsEmail
Wagner, P.D.University of California
Publisher:American Physiological Society
ISSN:8750-7587
Status:Published
Keywords:hypoxia; microgravity; mitochondrial respiration; muscle inactivity; oxidative function
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Research under Space Conditions
DLR - Research area:Raumfahrt
DLR - Program:R FR - Forschung unter Weltraumbedingungen
DLR - Research theme (Project):R - Vorhaben Integrative Studien (old)
Location: Köln-Porz
Institutes and Institutions:Institute of Aerospace Medicine > Space Physiology
Deposited By: Becker, Christine
Deposited On:09 Nov 2016 10:50
Last Modified:06 Sep 2019 15:27

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