Fig. 9.

Cl⁻ homeostasis in cultured neurons can be explained by the operation of an electroneutral K⁺–Cl⁻ cotransporter and the Gibbs–Donnan equilibrium. A, [Cl⁻]_i was calculated fromE_GABA listed in Table 2. Concentrations of the inorganic anions in the patch pipette were as indicated.Arrows indicate changes of [A⁻]_i calculated from changes inE_GABA of somatic or dendriticI_GABA induced by furosemide.Letters correspond to driving forces for the K⁺–Cl⁻ cotransporter derived from the energy profiles shown in B. B, Plot of the driving force for the K⁺–Cl⁻ cotransporter as a function of [K⁺]_o for different [Cl⁻]_i (taken fromE_GABA calculated for dendrites inA). Calculations are as described in Material and Methods. Positive values indicate outward transport.