Universität zu Köln

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:	Creators Email ORCID ORCID Put Code Salvadego, Desy UNSPECIFIED UNSPECIFIED UNSPECIFIED Keramidas, Michail E. UNSPECIFIED UNSPECIFIED UNSPECIFIED Koelegard, Roger UNSPECIFIED UNSPECIFIED UNSPECIFIED Brocca, Lorenza UNSPECIFIED UNSPECIFIED UNSPECIFIED Lazzer, Stefano UNSPECIFIED UNSPECIFIED UNSPECIFIED Mavelli, Irene UNSPECIFIED UNSPECIFIED UNSPECIFIED Rittweger, Joern UNSPECIFIED UNSPECIFIED UNSPECIFIED Eiken, Ola UNSPECIFIED UNSPECIFIED UNSPECIFIED Mekjavic, Igor B. UNSPECIFIED UNSPECIFIED UNSPECIFIED Grassi, Bruno UNSPECIFIED UNSPECIFIED UNSPECIFIED
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:	Keywords Language ARTERY BLOOD-FLOW; FUNCTION IN-VIVO; MITOCHONDRIAL-FUNCTION; EXERCISING MUSCLE; OVER-EXPRESSION; KNEE EXTENSION; HEART-FAILURE; OXYGEN-UPTAKE; EX-VIVO; METABOLISM Multiple languages Neurosciences; Physiology Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/17730