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Skeletal muscle mitochondria: the aerobic gate?
1Department of Zoology and Physiology, University of Wyoming, Laramie 82071.
Advances in Experimental Medicine and Biology
|January 1, 1988
Summary
Skeletal muscle mitochondria dictate an animal's maximum aerobic capacity (VO2max). The volume of these mitochondria determines oxygen (O2) demand, making them the primary regulator of O2 uptake in mammals.
Area of Science:
- Physiology
- Mitochondrial Biology
- Comparative Animal Physiology
Background:
- Maximum aerobic capacity (VO2max) is limited by oxygen (O2) consumption in skeletal muscle mitochondria.
- Upstream respiratory structures must support O2 delivery to meet muscle O2 demand.
- Factors like ontogeny, hypoxia, and training influence O2 delivery adaptations.
Purpose of the Study:
- To investigate the invariant relationship between skeletal muscle mitochondrial volume and an animal's maximum aerobic capacity.
- To determine if mitochondrial volume is the sole determinant of O2 demand and VO2max.
Main Methods:
- Comparative analysis of mammalian physiology across different body sizes.
- Examination of mitochondrial O2 consumption rates at the inner mitochondrial membrane.
- Correlation of mitochondrial volume with in vivo O2 uptake.
Main Results:
- A constant maximum mitochondrial O2 consumption rate was observed across diverse mammals (approx. 2000 O2 molecules/µm²/s).
- Total O2 uptake is predictably correlated with total active skeletal muscle mitochondrial volume.
- Skeletal muscle mitochondrial volume is a highly plastic respiratory structure.
Conclusions:
- Skeletal muscle mitochondria set the O2 demand, thereby dictating an animal's maximum aerobic capacity (VO2max).
- Mitochondrial volume is the critical factor controlling VO2max, independent of other respiratory system adaptations.