Hypoxia refines plasticity of mitochondrial respiration to repeated muscle work.

Desplanches, Dominique; Amami, Myriam; Dupré-Aucouturier, Sylvie; Valdivieso, Paola; Schmutz, Silvia; Müller, Matthias; Hoppeler, Hans-Heinrich; Kreis, Roland; Flück, Martin (2014). Hypoxia refines plasticity of mitochondrial respiration to repeated muscle work. European journal of applied physiology, 114(2), pp. 405-417. Springer 10.1007/s00421-013-2783-8

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PURPOSE We explored whether altered expression of factors tuning mitochondrial metabolism contributes to muscular adaptations with endurance training in the condition of lowered ambient oxygen concentration (hypoxia) and whether these adaptations relate to oxygen transfer as reflected by subsarcolemmal mitochondria and oxygen metabolism in muscle. METHODS Male volunteers completed 30 bicycle exercise sessions in normoxia or normobaric hypoxia (4,000 m above sea level) at 65% of the respective peak aerobic power output. Myoglobin content, basal oxygen consumption, and re-oxygenation rates upon reperfusion after 8 min of arterial occlusion were measured in vastus muscles by magnetic resonance spectroscopy. Biopsies from vastus lateralis muscle, collected pre and post a single exercise bout, and training, were assessed for levels of transcripts and proteins being associated with mitochondrial metabolism. RESULTS Hypoxia specifically lowered the training-induced expression of markers of respiratory complex II and IV (i.e. SDHA and isoform 1 of COX-4; COX4I1) and preserved fibre cross-sectional area. Concomitantly, trends (p < 0.10) were found for a hypoxia-specific reduction in the basal oxygen consumption rate, and improvements in oxygen repletion, and aerobic performance in hypoxia. Repeated exercise in hypoxia promoted the biogenesis of subsarcolemmal mitochondria and this was co-related to expression of isoform 2 of COX-4 with higher oxygen affinity after single exercise, de-oxygenation time and myoglobin content (r ≥ 0.75). Conversely, expression in COX4I1 with training correlated negatively with changes of subsarcolemmal mitochondria (r < -0.82). CONCLUSION Hypoxia-modulated adjustments of aerobic performance with repeated muscle work are reflected by expressional adaptations within the respiratory chain and modified muscle oxygen metabolism.

Item Type:

Journal Article (Original Article)

Division/Institute:

04 Faculty of Medicine > Department of Radiology, Neuroradiology and Nuclear Medicine (DRNN) > Institute of Diagnostic, Interventional and Paediatric Radiology > DCR Magnetic Resonance Spectroscopy and Methodology (AMSM)
04 Faculty of Medicine > Pre-clinic Human Medicine > Institute of Anatomy > Functional Anatomy
04 Faculty of Medicine > Pre-clinic Human Medicine > Institute of Anatomy
04 Faculty of Medicine > Pre-clinic Human Medicine > BioMedical Research (DBMR) > Forschungsbereich Pavillon 52 > Abt. Magnetresonanz-Spektroskopie und Methodologie, AMSM

UniBE Contributor:

Schmutz, Silvia; Müller, Matthias; Hoppeler, Hans-Heinrich; Kreis, Roland and Flück, Martin

Subjects:

600 Technology > 610 Medicine & health

ISSN:

1439-6319

Publisher:

Springer

Language:

English

Submitter:

Christoph Hans Boesch

Date Deposited:

24 Jul 2014 16:47

Last Modified:

23 Nov 2017 15:29

Publisher DOI:

10.1007/s00421-013-2783-8

PubMed ID:

24327174

BORIS DOI:

10.7892/boris.44034

URI:

https://boris.unibe.ch/id/eprint/44034

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