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Electrodiffusive Model for Astrocytic and Neuronal Ion Concentration Dynamics

Figure 3

Astrocyte model.

A representative astrocyte (I) exchanging ions with the ECS (E). As indicated, ions could cross the astrocytic membrane via passive Na⁺ or Cl⁻ channels, via the K⁺ Kir channel or the Na⁺/K⁺-pump. Ions could also be transported longitudinally by electrical migration or diffusion through the ICS () or ECS (). The cation-exchange input was a constant influx of K⁺ and efflux of Na⁺ to/from the ECS of the input zone (defined as the region ). The cation-exchange output was an efflux of K⁺ and influx Na⁺ from/to the ECS. The output was proportional to the local K⁺-concentration, and occurred over the whole axis. The decay zone was defined as the part of the axis where no input was applied (), i.e., the region where there was a net efflux of K+ from the system.

doi: https://doi.org/10.1371/journal.pcbi.1003386.g003