Simulation of experiments by Wu and Bers (2006) that measured the time course of Ca ²⁺ in the LSR after its partial depletion at the left end of the cell. (A) Time course of LSR [Ca²⁺] profile as Ca²⁺ diffuses with a diffusion coefficient of 0.6 × 10⁻¹⁰ m²/s. (B) LSR [Ca²⁺] time course at two ends of the model cell compared with an exponential fit to the experimental data (decay time constant = 27 s, dashed line).