Endurance training improves gastrocnemius mitochondrial function despite increased susceptibility to permeability...

Area of Science:

• Exercise Physiology
• Mitochondrial Biology
• Cellular Respiration

Background:

• Endurance training is known to enhance mitochondrial function.
• The effect of training on the mitochondrial permeability transition pore (MPTP) remains less understood.
• Investigating MPTP opening is crucial for understanding cellular adaptation to exercise.

Purpose of the Study:

• To test if moderate endurance treadmill training improves gastrocnemius mitochondrial bioenergetics.
• To determine if training increases tolerance to calcium-induced mitochondrial permeability transition pore (MPTP) opening.

Main Methods:

• Adult male Wistar rats were divided into sedentary and trained groups.
• Trained rats underwent 14 weeks of treadmill running (60 min/day).
• Gastrocnemius mitochondrial function, including oxygen consumption and MPTP opening susceptibility, was assessed in vitro. Caspase-9 activity was measured.

Main Results:

• Endurance training significantly increased state 3 respiration and respiratory control ratio with both complex I and II substrates.
• Increased CCCP-induced uncoupled respiration was observed with succinate.
• Contrary to the hypothesis, trained rats showed increased susceptibility to calcium-induced MPTP opening and elevated caspase-9 activity.

Conclusions:

• Endurance training enhances gastrocnemius mitochondrial respiratory function.
• Training leads to mitochondrial and cellular alterations that increase susceptibility to calcium-induced MPTP opening.
• The findings suggest a complex interplay between exercise adaptation and mitochondrial stability.