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Anaplerotic processes in human skeletal muscle during brief dynamic exercise
M J Gibala1, D A MacLean, T E Graham
1Department of Human Biology and Nutritional Sciences, University of Guelph, Ontario, Canada. mgibala@uoguelph.ca
The Journal of Physiology
|August 1, 1997
Summary
During intense exercise, human skeletal muscle rapidly increases tricarboxylic acid cycle intermediates (TCAIs). The alanine aminotransferase reaction is key for fueling this energy demand.
Area of Science:
- Exercise Physiology
- Skeletal Muscle Metabolism
- Biochemistry
Background:
- Tricarboxylic acid cycle intermediates (TCAIs) are crucial for energy production in skeletal muscle.
- Understanding TCAI dynamics during exercise is vital for comprehending muscle energy metabolism.
Purpose of the Study:
- To investigate the changes in TCAIs in human skeletal muscle during dynamic exercise and recovery.
- To identify the primary metabolic pathways contributing to TCAI fluctuations during the initial minutes of exercise.
Main Methods:
- Human skeletal muscle samples were analyzed for TCAI concentrations.
- Measurements were taken at rest, during 5 minutes of dynamic knee extensor exercise (80% max workload), and after 2 minutes of recovery.
Main Results:
- The sum of TCAIs significantly increased during exercise, peaking at 5 minutes and remaining elevated during recovery.
- Succinate, malate, and fumarate were the primary drivers of the TCAI increase.
- Intramuscular alanine and pyruvate levels rose, while glutamate decreased, suggesting the alanine aminotransferase reaction's role.
Conclusions:
- The alanine aminotransferase reaction is identified as the most significant anaplerotic pathway during the initial phase of human skeletal muscle contraction.
- These findings provide insights into the rapid metabolic adjustments occurring in skeletal muscle during high-intensity exercise.