[Effects of Continuous Training on the Induction of Atrial Fibrillation in a Rabbit Model].

Area of Science:

• Cardiology
• Exercise Physiology
• Molecular Biology

Background:

• Continuous training is associated with cardiovascular adaptations.
• Atrial fibrillation (AF) is a growing concern, and its relationship with exercise intensity requires further investigation.
• Understanding the mechanisms of exercise-induced AF is crucial for preventative strategies.

Purpose of the Study:

• To investigate the mechanisms behind continuous training-induced atrial fibrillation (AF) in a rabbit model.
• To assess the impact of moderate and high-intensity continuous training on atrial electrophysiology and structure.

Main Methods:

• New Zealand rabbits were subjected to 12 weeks of moderate or high-intensity treadmill training.
• Atrial fibrillation was induced using S1S2 stimulation.
• Quantitative real-time PCR and Masson staining were used to analyze gene expression and collagen content.

Main Results:

• High-intensity training significantly increased AF incidence and atrial collagen volume fraction (CVF) compared to controls.
• Gene expression of kir2.1, kir2.2, and collagen types I and III in the left atrium was elevated in the high-intensity group.
• Atrial inward rectifier potassium current/channel (IK1) was also increased in trained groups.

Conclusions:

• Long-term, high-intensity treadmill running can lead to an increased incidence of atrial fibrillation in rabbits.
• These findings suggest that exercise-induced AF may be linked to alterations in ion channel expression and cardiac fibrosis.