Figure 2
A KCC2-like Cl− extrusion affects the tortuosity of Cl− diffusion to a lesser extent than spines.
(A) Removal of Cl− ions by a KCC2-like pump was added to simulations from Fig. 1 using exponentially decaying pool model of Cl− concentration. The time constant for Cl− extrusion (τCl) was 3000 ms. The tortuosity was calculated and compared for 2 different conditions: active Cl− pump (pump on) and inactive Cl− pump (pump off). The presence of active Cl− pump in the dendrite did not change the tortuosity of Cl− diffusion. (B) Same simulations as in A but in the presence of nonuniform Cl− extrusion. Top schematic: Active Cl− pump was inserted in two distal thirds of the dendritic shaft. Note a small increase in tortuosity for such nonuniformly distributed Cl− pump (pump on-off-on) as compared to inactive (pump off) or uniformly distributed Cl− pump (pump on). Spines increased tortuosity more than did the nonuniform Cl− pump. (C) Same simulations as in A and B but in the presence of active Cl− pump selectively in spines and adjacent dendritic shafts (pump on in spines and shafts, top schematic). For comparison, active Cl− pump was inserted everywhere (pump on) or only in spines (pump on in spines).
