Votion 2012 PLoS One
|Votion DM, Gnaiger E, Lemieux H, Mouithys-Mickalad A, Serteyn D (2012) Physical fitness and mitochondrial respiratory capacity in horse skeletal muscle. PLoS One 7:e34890.|
Abstract: Background: Within the animal kingdom, horses are among the most powerful aerobic athletic mammals. Determination of muscle respiratory capacity and control improves our knowledge of mitochondrial physiology in horses and high aerobic performance in general.
We applied high-resolution respirometry and multiple substrate-uncoupler-inhibitor titration protocols to study mitochondrial physiology in small (1.0 – 2.5 mg) permeabilized muscle fibres sampled from triceps brachii of healthy horses. Oxidative phosphorylation (OXPHOS) capacity [pmol O2∙s-1∙mg-1 wet weight] in the NADH&succinate-pathway (NS, combined [[CI&II]]-linked substrate supply: glutamate&malate&succinate) increased from 77±18 in overweight horses to 103±18, 122±15, and 129±12 in untrained, trained andcompetitive horses (N = 3, 8, 16, and 5, respectively). Similar to human muscle mitochondria, equine OXPHOS capacity was limited by the phosphorylation system to 0.85±0.10 (N = 32) of electron transfer capacity, independent of fitness level. In 15 trained horses, OXPHOS capacity increased from 119±12 to 134±37 when pyruvate was included in the NS-substrate cocktail. Relative to this maximum OXPHOS capacity, NADH-linked OXPHOS capacities (N) were only 50% with glutamate&malate, 64% with pyruvate&malate, and 68% with pyruvate&glutamate&malate, and ~78% with succinate&rotenone (S). OXPHOS capacity with glutamate&malate increased with fitness relative to NS-supported ET capacity from a flux control ratio of 0.38 to 0.40, 0.41 and 0.46 in overweight to competitive horses, whereas the S/NS substrate control ratio remained constant at 0.70. Therefore, the apparent deficit of the N- over S-pathway capacity was reduced with physical fitness.
The scope of mitochondrial density-dependent OXPHOS capacity and the density-independent (qualitative) increase of N-respiratory capacity with increased fitness open up new perspectives of integrative and comparative mitochondrial respiratory physiology.
• Keywords: horse, skeletal muscle, microbiopsy, permeabilized fibres, mitochondria, OXPHOS capacity, high-resolution respirometry
- * Contribution to K-Regio project MitoCom Tyrol, funded by the Tyrolian Government and the European Regional Development Fund.
- 2017-01-29 Abstract edited with updated terminology: » MitoPedia: SUIT
- Gnaiger E (2020) Mitochondrial pathways and respiratory control. An introduction to OXPHOS analysis. 5th ed. Bioenerg Commun 2020.2:112 pp. doi:10.26124/bec:2020-0002
Labels: MiParea: Respiration, mt-Biogenesis;mt-density, Comparative MiP;environmental MiP, Exercise physiology;nutrition;life style Pathology: Obesity Stress:Ischemia-reperfusion Organism: Horse Tissue;cell: Skeletal muscle Preparation: Permeabilized tissue
Coupling state: LEAK, OXPHOS, ET Pathway: N, S, NS HRR: Oxygraph-2k, O2k-Protocol
SUIT-011, SUIT-008, SUIT-006, SUIT-008 O2 pfi D014, SUIT-011 O2 pfi D024, BEC 2020.2