Figure 3.

Action potentials, calcium transients, and [Na⁺]_i in optimized models. (A) Optimized models have similar action potentials under control conditions, but the different parameter sets underlying the different solutions give rise to some waveform variation. (B) Despite having comparable action potentials, models optimized without constraints on [Ca²⁺]_i and [Na⁺]_i can have widely different calcium transients. Shaded areas give constraints on minimum and maximum [Ca²⁺]_i (0.05–0.15 and 0.3–0.7μM, respectively). (C) Without constraints on [Ca²⁺]_i and [Na⁺]_i, optimization can result in models with very low [Na⁺]_i levels. Shaded area indicate constraint on [Na⁺]_i (7–10mM). “APD_LQT±βAdr” designates the original optimization to clinical LQT data under normal and β-adrenergic stimulation conditions by Mann et al. (2016).