Automaticity in ventricular myocyte cell pairs with ephaptic and gap junction coupling

Area of Science:

• Cardiology
• Computational Biology
• Biophysics

Background:

• Spontaneous electrical activity (automaticity) is crucial for heart function.
• Irregular ventricular automaticity can lead to life-threatening cardiac arrhythmias.
• Ephatic coupling through extracellular clefts has been proposed to influence automaticity.

Purpose of the Study:

• To investigate the dynamics of coupled excitable cells incorporating both ephatic and gap junction coupling.
• To explore mechanisms promoting automaticity and synchronization in cardiac cells.

Main Methods:

• Computational modeling of coupled excitable cells.
• Analysis of Hopf bifurcations to identify conditions for automaticity.
• Exploration of parameter space including ion channel fractions and cleft volume.

Main Results:

• Automaticity and synchronization robustly emerge by increasing inward rectifying potassium current (I_K1) at the junctional membrane or decreasing cleft volume.
• Heterogeneity in potassium channel distribution can lead to varied automaticity and synchronization outcomes.
• Gap junction coupling has minimal impact on the emergence of automaticity.

Conclusions:

• Ephatic coupling, influenced by potassium channels and cleft geometry, plays a significant role in cardiac automaticity.
• Findings provide insights into novel mechanisms underlying spontaneous activity and potential triggers for arrhythmias.
• This research contributes to understanding the complex dynamics of cardiac electrical activity.