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How different two almost identical action potentials can be: a model study on cardiac repolarization
Massimiliano Zaniboni1, Irene Riva, Francesca Cacciani
1Dipartimento di Biologia Evolutiva e Funzionale, Sezione Fisiologia, Università degli Studi di Parma, V.le G.P. Usberti 11 A, 43124 Parma, Italy. massimiliano.zaniboni@unipr.it
Mathematical Biosciences
|August 31, 2010
Summary
Cardiac cell models with similar action potentials can exhibit distinct electrical properties. Differences in ion channel function and coupling become apparent under pathological conditions, impacting repolarization and conduction.
Area of Science:
- Computational Biology
- Cardiac Electrophysiology
- Mathematical Modeling
Background:
- Spatial heterogeneity in ion channel properties influences ventricular repolarization.
- Gap junctional coupling modulates this dispersion, but differences can be electrophysiologically silent under normal conditions.
Purpose of the Study:
- To identify modified cardiac cell model parameters that yield similar action potentials but differ in electrical properties.
- To investigate the electrotonic interactions and pathological manifestations of these distinct models.
Main Methods:
- Numerical simulation using the Luo-Rudy phase 1 model.
- Modification of model parameters to generate a second action potential profile (AP2).
- Analysis of electrotonic interactions in cell pairs and cable conduction.
Main Results:
- AP2 membranes are weaker current sources with altered sensitivity to ion channel modulation and extracellular potassium.
- Differences in source-sink properties emerge during intercellular uncoupling or partial ion channel block.
- Unidirectional block and spatial repolarization gradients were observed under simulated pathological conditions.
Conclusions:
- Cardiac cell models with similar action potentials can possess fundamentally different electrical behaviors.
- Comprehensive characterization and validation of cell models are crucial for accurate simulation results.
- Inverse problem characterization highlights the need for detailed model scrutiny.
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