Larsen 2012 Acta Physiol (Oxf)
| Larsen S, Hey-Mogensen M, Rabøl R, Stride N, Helge JW, Dela F (2012) The influence of age and aerobic fitness: Effects on mitochondrial respiration in skeletal muscle. Acta Physiol (Oxf) Epub ahead of print. |
Larsen S, Hey-Mogensen M, Rabøl R, Stride N, Helge JW, Dela F (2012) Acta Physiol (Oxf)
Abstract: 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.
Labels:
Stress:Aging; Senescence"Aging; Senescence" is not in the list (Cell death, Cryopreservation, Ischemia-reperfusion, Permeability transition, Oxidative stress;RONS, Temperature, Hypoxia, Mitochondrial disease) of allowed values for the "Stress" property. Organism: Human Tissue;cell: Skeletal Muscle"Skeletal Muscle" is not in the list (Heart, Skeletal muscle, Nervous system, Liver, Kidney, Lung;gill, Islet cell;pancreas;thymus, Endothelial;epithelial;mesothelial cell, Blood cells, Fat, ...) of allowed values for the "Tissue and cell" property. Preparation: z in prep"z in prep" is not in the list (Intact organism, Intact organ, Permeabilized cells, Permeabilized tissue, Homogenate, Isolated mitochondria, SMP, Chloroplasts, Enzyme, Oxidase;biochemical oxidation, ...) of allowed values for the "Preparation" property. Enzyme: z in prep"z in prep" is not in the list (Adenine nucleotide translocase, Complex I, Complex II;succinate dehydrogenase, Complex III, Complex IV;cytochrome c oxidase, Complex V;ATP synthase, Inner mt-membrane transporter, Marker enzyme, Supercomplex, TCA cycle and matrix dehydrogenases, ...) of allowed values for the "Enzyme" property. Regulation: z in prep"z in prep" is not in the list (Aerobic glycolysis, ADP, ATP, ATP production, AMP, Calcium, Coupling efficiency;uncoupling, Cyt c, Flux control, Inhibitor, ...) of allowed values for the "Respiration and regulation" property.
HRR: Oxygraph-2k
