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Reduced running endurance in gluconeogenesis-inhibited rats
The American Journal of Physiology
|July 1, 1986
Summary
Gluconeogenesis is vital for endurance. Inhibiting this process significantly reduced exercise time in both trained and untrained rats by depleting essential energy substrates like blood glucose.
Area of Science:
- Exercise Physiology
- Metabolic Biochemistry
Background:
- Submaximal exercise relies on metabolic substrates for sustained energy.
- Gluconeogenesis plays a role in maintaining energy homeostasis during prolonged activity.
Purpose of the Study:
- To investigate the functional significance of gluconeogenesis in endurance performance.
- To assess the impact of inhibiting gluconeogenesis on metabolic markers of fatigue.
Main Methods:
- Gluconeogenesis was inhibited using 3-mercaptopicolinic acid (3-MPA) targeting the phosphoenolpyruvate carboxykinase reaction.
- Endurance capacity and metabolic substrates (glycogen, glucose, lactate, glycerol, free fatty acids) were measured in untrained and trained rats.
Main Results:
- 3-MPA significantly reduced endurance in both untrained (-32%) and trained (-26%) rats.
- At exhaustion, 3-MPA treated rats exhibited depleted hepatic glycogen (3%), white quadriceps glycogen (46%), and blood glucose (37%) compared to controls.
- Plasma free fatty acids remained elevated in controls but returned to resting levels in hypoglycemic 3-MPA treated rats.
Conclusions:
- Gluconeogenesis is crucial for maintaining blood glucose levels during submaximal exercise.
- Inhibition of gluconeogenesis impairs endurance performance by depleting key metabolic substrates.