Salvadego, Desy, Keramidas, Michail E., Koelegard, Roger, Brocca, Lorenza, Lazzer, Stefano, Mavelli, Irene, Rittweger, Joern, Eiken, Ola, Mekjavic, Igor B. and Grassi, Bruno (2018). PlanHab(*): hypoxia does not worsen the impairment of skeletal muscle oxidative function induced by bed rest alone. J. Physiol.-London, 596 (15). S. 3341 - 3356. HOBOKEN: WILEY. ISSN 1469-7793

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Abstract

Skeletal muscle oxidative function was evaluated in 11 healthy males (mean +/- SD age 27 +/- 5years) prior to (baseline data collection, BDC) and following a 21day horizontal bed rest (BR), carried out in normoxia (P-IO2=133 mmHg; N-BR) and hypoxia (P-IO2=90 mmHg; H-BR). H-BR was aimed at simulating reduced gravity habitats. The effects of a 21day hypoxic ambulatory confinement (P-IO2=90 mmHg; H-AMB) were also assessed. Pulmonary O-2 uptake (<(V) over dot>O-2), vastus lateralis fractional O-2 extraction (changes in deoxygenated haemoglobin+myoglobin concentration, Delta[deoxy(Hb+Mb)]; near-infrared spectroscopy) and femoral artery blood flow (ultrasound Doppler) were evaluated during incremental one-leg knee-extension exercise (reduced constraints to cardiovascular O-2 delivery) carried out to voluntary exhaustion in a normoxic environment. Mitochondrial respiration was evaluated ex vivo by high-resolution respirometry in permeabilized vastus lateralis fibres. <(V) over dot>(O2peak) decreased (P<0.05) after N-BR (0.98 +/- 0.13 L min(-1)) and H-BR (0.96 +/- 0.17 L min(-1)) vs. BDC (1.05 +/- 0.14 L min(-1)). In the presence of a decreased (by similar to 6-8%) thigh muscle volume, <(V) over dot>(O2peak) normalized per unit of muscle mass was not affected by both interventions. Delta[deoxy(Hb+Mb)](peak) decreased (P<0.05) after N-BR (65 +/- 13% of limb ischaemia) and H-BR (62 +/- 12%) vs. BDC (73 +/- 13%). H-AMB did not alter <(V) over dot>(O2peak) or Delta[deoxy(Hb+Mb)](peak). An overshoot of Delta[deoxy(Hb+Mb)] was evident during the first minute of unloaded exercise after N-BR and H-BR. Arterial blood flow to the lower limb during both unloaded and peak knee extension was not affected by any intervention. Maximal ADP-stimulated mitochondrial respiration decreased (P<0.05) after all interventions vs. control. In 21day N-BR, a significant impairment of oxidative metabolism occurred downstream of cardiovascular O-2 delivery, affecting both mitochondrial respiration and presumably the intramuscular matching between O-2 supply and utilization. Superposition of H on BR did not worsen the impairment induced by BR alone.

Item Type: Journal Article
Creators:
CreatorsEmailORCIDORCID Put Code
Salvadego, DesyUNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Keramidas, Michail E.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Koelegard, RogerUNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Brocca, LorenzaUNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Lazzer, StefanoUNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Mavelli, IreneUNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Rittweger, JoernUNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Eiken, OlaUNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Mekjavic, Igor B.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Grassi, BrunoUNSPECIFIEDUNSPECIFIEDUNSPECIFIED
URN: urn:nbn:de:hbz:38-177304
DOI: 10.1113/JP275605
Journal or Publication Title: J. Physiol.-London
Volume: 596
Number: 15
Page Range: S. 3341 - 3356
Date: 2018
Publisher: WILEY
Place of Publication: HOBOKEN
ISSN: 1469-7793
Language: English
Faculty: Unspecified
Divisions: Unspecified
Subjects: no entry
Uncontrolled Keywords:
KeywordsLanguage
ARTERY BLOOD-FLOW; FUNCTION IN-VIVO; MITOCHONDRIAL-FUNCTION; EXERCISING MUSCLE; OVER-EXPRESSION; KNEE EXTENSION; HEART-FAILURE; OXYGEN-UPTAKE; EX-VIVO; METABOLISMMultiple languages
Neurosciences; PhysiologyMultiple languages
Refereed: Yes
URI: http://kups.ub.uni-koeln.de/id/eprint/17730

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