Adaptation of rabbit ventricular cell model to reproduce action potentials in isolated papillary muscle

Aims: We sought to establish a computational model of the rabbit ventricular action potential (AP) suitable for investigation of drug effects on the AP of the isolated rabbit papillary muscle. Methods: Data consisted of transmembrane AP recordings from isolated right ventricular papillary muscles from 21 rabbits. An existing model of the rabbit ventricular AP was adapted to reproduce experimental AP amplitude and AP duration (APD₉₀, APD₆₀, APD₃₀,) at multiple pacing rates by reduction of fast sodium current and overall depolarizing current. The resulting model was validated. Results: At 2.0 and 0.5 Hz pacing respectively, the experimentally recorded APD₉₀ was 113.9±11.2 ms and 150.2±13.1 ms. The adapted model produced an APD₉₀ of 130.5 ms and 142.5 ms. Validation of the adapted model showed that, while there was a substantial adaptation of the model APD to experimental data, model stability was maintained, and internal Ca dynamics and responses to stimuli were not substantially affected. Conclusion: A model of the rabbit ventricular AP was adapted in order to reproduce experimental AP recordings from the isolated right ventricular rabbit papillary muscle. This model is useful for analysis of drug effects on the rabbit papillary AP.