Calcium transients in the submembrane shell (black lines) and the compartment core (blue dashed lines) of a two pool model that includes a membrane-bound pump and diffusion into the core. Initial concentration Ca0 is 0.05 μM throughout. Calcium current as in Figure 6.3. Compartment length is 1 μm. (a) Compartment diameter is 1 μm, shell thickness is 0.1 μm; (b) Compartment diameter is 1 μm, shell thickness is 0.01 μm; (c) Compartment diameter is 4 μm, shell thickness is 0.1 μm. Diffusion: DCa = 2.3 × 10−6 cm2 s−1; Pump: Vpump = 10−11 mol cm−2 s−1, Kpump = 10 μM, Jleak = Vpump ∗ Ca0/(Kpump + Ca0).
