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Updated: May 21, 2026
09:50
Application of Chronic Stimulation to Study Contractile Activity-induced Rat Skeletal Muscle Phenotypic Adaptations
Published on: January 25, 2018
Contractile activity-induced mitochondrial biogenesis and mTORC1
Heather N Carter1, David A Hood
1Muscle Health Rsearch Centre, School of Kinesiology and Health Science, York Univ., Toronto, Ontario, M3J 1P3, Canada.
American Journal of Physiology. Cell Physiology
|June 16, 2012
Summary
Chronic contractile activity (CCA) increases skeletal muscle mitochondrial content, but the mammalian target of rapamycin complex 1 (mTORC1) pathway is not essential for this adaptation. mTORC1 is crucial for maintaining mitochondrial function in resting muscle.
Area of Science:
- Exercise Physiology
- Molecular Biology
- Cellular Metabolism
Background:
- Skeletal muscle mitochondrial content increases with exercise training.
- Molecular mechanisms driving mitochondrial adaptation to chronic contractile activity (CCA) are not fully understood.
- The mammalian target of rapamycin complex 1 (mTORC1) pathway regulates mitochondrial proteins in resting muscle.
Purpose of the Study:
- To investigate if the mTORC1 pathway mediates mitochondrial biogenesis during CCA.
- To determine the role of mTORC1 in skeletal muscle adaptation to chronic contractile activity.
Main Methods:
- Murine skeletal muscle cells (myotubes) were subjected to CCA in culture.
- The mTORC1 inhibitor rapamycin was used to assess pathway involvement.
- Mitochondrial markers (cytochrome oxidase IV, Tfam) and COX activity were measured.
Main Results:
- CCA increased mitochondrial markers and COX activity.
- Rapamycin did not inhibit CCA-induced increases in mitochondrial content.
- mTORC1 inhibition alone upregulated mitochondrial proteins but impaired respiration, an effect reversed by CCA.
Conclusions:
- mTORC1 activity is not required for the increase in mitochondrial content induced by CCA.
- mTORC1 is essential for maintaining mitochondrial function and homeostasis in resting skeletal muscle.
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