Document Detail

The influence of age and aerobic fitness: Effects on mitochondrial respiration in skeletal muscle.
MedLine Citation:
PMID:  22212519     Owner:  NLM     Status:  Publisher    
AIM: Mitochondrial function has previously been studied in ageing, but never in humans matched for maximal oxygen uptake (V·O2max). Furthermore, the influence of ageing on mitochondrial substrate sensitivity is not known. METHODS: Skeletal muscle mitochondrial respiratory capacity and mitochondrial substrate sensitivity was measured by respirometry in young (23±3 years) and middle-aged (53±3 years) male subjects with similar V·O2max. Protocols for respirometry included titration of substrates for complexI (glutamate), complexII (succinate) and both (octanoyl-carnitine) for calculation of substrate sensitivity (C(50) ). Myosin Heavy Chain (MHC) isoforms, citrate synthase (CS) and β-hydroxy-acyl-CoA-dehydrogenase (HAD) activity, mitochondrial DNA (mtDNA) content, protein levels of complexes I-V and antioxidant defense system (manganese superoxide dismutase (MnSOD)) was measured. RESULTS: No differences were found in maximal mitochondrial respiration or C(50) with glutamate (2.0±0.3 and 1.8±0.3 mmol/l), succinate (3.7±0.2 and 3.8±0.4 mmol/l) or octanoyl-carnitine (47±8 and 56±7 μmol/l) in young and middle-aged subjects, respectively. Normalising mitochondrial respiration to mtDNA young subjects had a higher (P<0.05) respiratory capacity per mitochondrion compared to middle-aged subjects. HAD activity and mtDNA per mg tissue were higher in middle-aged compared to young subjects. Middle-aged had a higher MHC I isoform and a lower MHC IIX isoform content compared to young subjects. CONCLUSION: Mitochondrial substrate sensitivity is not affected by ageing. When young and middle-aged men are carefully matched for V·O2max, mitochondrial respiratory capacity is also similar. However, per mitochondrion respiratory capacity was lower in middle-aged compared to young subjects. Thus, when matched for V·O2max middle-aged seems to require a higher mitochondrial content than young subjects.
Steen Larsen; Martin Hey-Mogensen; Rasmus Rabøl; Nis Stride; Jørn W Helge; Flemming Dela
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-1-2
Journal Detail:
Title:  Acta physiologica (Oxford, England)     Volume:  -     ISSN:  1748-1716     ISO Abbreviation:  -     Publication Date:  2012 Jan 
Date Detail:
Created Date:  2012-1-3     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101262545     Medline TA:  Acta Physiol (Oxf)     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
© 2011 The Authors Acta Physiologica © 2011 Scandinavian Physiological Society.
Xlab, Center for Healthy Aging, Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3b, Copenhagen, Denmark.
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