Skeletal muscle oxidative function after a 10-day exposure to hypoxia and microgravity
2013 (English)Conference paper, Abstract (Refereed)
Skeletal muscle oxidative function was evaluated before (CTRL) and after 10 days of normobaric hypoxic (inspired PO2 12.5kPa) bed rest (H-BR) and normoxic bed rest (BR) in nine healthy young men (age: 24.1±1.7 years [mean±SD]). H-BR was taken as a simulation of lunar habitats. Pulmonary gas exchange and vastus lateralis muscle fractional O2-extraction (by near-infrared spectroscopy) were determined during an incremental cycle ergometer (CE) and one-leg knee extension (KE) exercise up to volitional exhaustion. Mitochondrial respiration was evaluated by high-resolution respirometry in permeabilized vastus lateralis fibers. During CE, peak pulmonary O2-uptake ( VO 2peak) significantly decreased by ~7 and 9 % after BR and
H-BR, respectively. During KE, V O 2peak decreased significantly (by ~6%) after BR (0.83±0.07 vs. 0.89±0.08 [CTRL] L·min-1), but not after H-BR (0.86±0.07 vs. 0.90±0.07). Skeletal muscle peak fractional O2-extraction was significantly lower after BR (60±12 vs. 70±11% [CTRL]), but not after H-BR (65±12 vs. 71±10). No significant changes were observed in maximal ADP-stimulated mitochondrial respiration either after BR (48.9±11.5pmolO2·s-1·mg-1 wet weight) or H-BR (42.8±7.8) vs. CTRL (46.6±6.6). After relieving, by the KE exercise protocol, constraints related to cardiovascular O2-delivery, oxidative function in vivo was still impaired after BR, while a less pronounced impairment was evident after H-BR. Mitochondrial respiratory function ex-vivo was unchanged after both conditions. Peripheral O2-diffusion constraints and/or an impaired O2-delivery/O2-utilization coupling might be the main bottleneck to oxidative function in vivo after BR. Hypoxia may attenuate the impairment of muscle oxidative function observed after BR.
Place, publisher, year, edition, pages
IdentifiersURN: urn:nbn:se:kth:diva-134619OAI: oai:DiVA.org:kth-134619DiVA: diva2:667284
EMC 2013 42nd EUROPEAN MUSCLE CONFERENCE; Amsterdam, Netherlands, September 21-25, 2013
QC 201406252013-11-262013-11-262014-06-25Bibliographically approved