Table 1.
Parameter values for “parsimonious rabbit” (PR) model.
Fig 1.
Dynamic I-V curves from isolated cells.
A) Transmembrane potential (Vm) recorded during the action potential upstroke from six isolated rabbit cells from [43]. B) Current-voltage (I-V) relationship plotted as INa (models: lines) or (experiments: ●) versus Vm. C) Predicted Vm signals from models (lines) and average from experiments (●) during the upstroke.
Fig 2.
Dynamic I-V relationship during propagation.
A) Current-voltage (I-V) relationship plotted as INa (models) or Iion (experiments: ● from [33]) versus Vm. Values of CV for each model are shown at the top. B) Predicted transmembrane potential (Vm) for the action potential upstroke during propagation for the models (lines) and average from experiments (●).
Fig 3.
Recovery of AP excitability virtual protocol.
A) Average Vm (●) of six experimental cells shown in inset, aligned to recovery time (RT: defined as the time at which Vm recovers to within 5 mV of the resting potential). B) Normalized peak INa (models: lines) or (experiments: ●) as a function of RT. Experimental values of RT at 50% (0.8 ± 0.8 ms) and at 82% (4.7 ± 0.8 ms) were taken from in Table 1 of [32]. The error bars in B) reflect the variability of AP shape of the six cells (see panel A). The novel action potential clamp virtual protocol is described in the text.
Fig 4.
Voltage dependence of steady state INa activation (A), time constant for activation (B), steady state INa inactivation (C), and time constant for inactivation (D) for the PR (black), LR1 (grey), and EJ (dashed grey) models (note the log scale).
Fig 5.
Simulations of functional reentry for PR model (A) and Mahajan model (B). Tip trajectories overlaid in yellow, green, and blue, 5 cm x 5 cm grids and D = 1 cm2/s.
Fig 6.
Spiral wave dynamics as a function of repolarization current IK parameters (gK and b).
Snapshots of spiral wave patterns are shown in grey scale with the tip trajectories overlaid in yellow. Example Vm signal from one site is shown under each panel with the dashed horizontal lines indicating -83 and 0 mV. Simulations (dt = 0.02 ms and dx = 0.01 cm) were carried out on 4.8 cm x 4.8 cm grids and D = 1 cm2/s with the exception of the top two right panels where D = 0.25 cm2/s to account for the larger wavelength. Red boxes indicate that the corresponding videos are available online.
Fig 7.
Cellular alternans in PR model during pacing.
A) Beat-to-beat dynamics of sequential action potentials during periodic pacing at BCL = 202 ms. B) The corresponding dynamics of the activation m (dashed line) and inactivation h (solid line) variables. Note the similarity of m for subsequent beats while h alternates as shown by arrows. Bifurcation diagrams illustrating steady state alternans in C) and
D) as a function of BCL.