Figure 4.
Predictions of the diffusion-limited model for high astrocyte water permeability. Pf = 0.04 cm/s for computations in this figure. (A) Schematic showing nonlinear and newly added mesh elements in astrocyte cytoplasm used for numerical solution of the diffusion equation. See text for explanation. (B) Time course of [K+]e, de, ψ, JKa, and JVa after neuroexcitation for the indicated cytoplasmic diffusion coefficients, Da. Parameters: PK = 1.2 × 10−5 cm/s, JKno = 10−8 mol/cm2/s, Δtn = 0.1 s, da = 10 µm, and de = 2 µm. (C and D) Astrocyte spatial distribution of [K+]a and [non-K+]a at the indicated times, with parameters as in B, for Da = 10−8 cm2/s (C) and t = 5 s (D). (E) Effect of duration of neuroexcitation. Computations as in B, with PK = 1.3 × 10−5 cm/s, JKno = 8 × 10−10 mol/cm2/s, and Δtn = 10 s.