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Phase resetting and bifurcation in the ventricular myocardium
Biophysical Journal
|May 1, 1985
Summary
Investigating ventricular muscle fiber dynamics using Beeler-Reuter equations, this study reveals how applied current changes firing modes from periodic spiking to chaos. Brief current pulses can reset or annihilate this firing, transitioning the cell to a steady state.
Area of Science:
- Computational biology
- Cardiac electrophysiology
Background:
- The Beeler-Reuter (BR) equations model ventricular myocyte electrophysiology.
- Understanding oscillatory behavior is crucial for cardiac function and dysfunction.
Purpose of the Study:
- To investigate the oscillatory behavior of ventricular muscle fibers under varying applied currents using BR equations.
- To analyze phase resetting and annihilation phenomena through dynamic perturbation.
Main Methods:
- Simulated ventricular myocyte electrophysiology using Beeler-Reuter dynamic differential equations.
- Applied depolarizing current (I app) to induce different firing modes.
- Conducted bifurcation analysis and examined phase resetting and annihilation with current pulses.
Main Results:
- Increased applied current (I app) led to transitions from periodic spiking to bursting and finally to chaos.
- Phase resetting and annihilation of repetitive firing were demonstrated with specific current pulses.
- Bifurcation analysis revealed stable periodic solutions and Hopf bifurcations, indicating coexistence of oscillatory and steady states.
Conclusions:
- The BR model predicts complex dynamic behaviors in ventricular myocytes, including chaotic regimes.
- Dynamic perturbation methods, like brief current pulses, can effectively alter cellular states, transitioning from rhythmic firing to a steady state.
- Bifurcation analysis is a valuable tool for understanding the stability and transitions of cardiac cell models.