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Role of ionic electrodiffusion and ephaptic coupling in cardiac dynamics
1Purdue University, Department of Mathematics, West Lafayette, Indiana.
Biophysical Journal
|August 13, 2025
Summary
Ephaptic coupling (EpC) complements gap junctions (GJs) in heart electrical signaling. This study models EpC and electrodiffusion, revealing EpC enhances conduction and stabilizes electrical propagation, especially during heart disease.
Area of Science:
- Cardiovascular physiology
- Computational biology
- Electrophysiology
Background:
- Cardiac myocytes communicate electrically via gap junctions (GJs) for coordinated contractions.
- Alternative mechanisms like ephaptic coupling (EpC) exist, especially when GJs are compromised.
- Existing models lack the combined influence of EpC and electrodiffusion in cardiac conduction.
Purpose of the Study:
- To develop a computational model incorporating EpC and multidomain electrodiffusion.
- To investigate the interplay between EpC and electrodiffusion on cardiac action potential (AP) propagation.
- To understand the physiological and pathological roles of EpC in heart function.
Main Methods:
- Developed a two-dimensional discrete multidomain electrodiffusion model.
- Included ephaptic coupling (EpC) within the model.
- Analyzed action potential (AP) propagation, morphology, and electrochemical properties.
Main Results:
- Strong EpC enhances Na+ electrodiffusion, increasing conduction velocity and reducing block.
- Ca2+ and K+ diffusion, influenced by EpC, alter AP duration and repolarization.
- EpC stabilizes AP propagation, aiding spread into ischemic regions and altering cleft ion concentrations.
Conclusions:
- The developed model provides insights into EpC mechanisms in cardiac electrophysiology.
- EpC plays a significant role in cardiac conduction, particularly under disease conditions.
- EpC influences ion dynamics and electrical signal propagation in the heart.
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