Figure 7.

Pharmacology of Cl⁻ accumulation. A, Recovery process of E_GABA after depletion protocol under control conditions (open squares; n = 26), in Na⁺-free ACSF (filled circles; n = 7) and in the presence of 50 μm bumetanide (gray triangles; n = 10). The recovery process and final E_GABA were altered by bumetanide and Na⁺-free ACSF. B, Typical responses to GABA application protocols used to determine E_GABA after recovery in ACSF, 50 μm bumetanide (Bum), and Na⁺-free ACSF (0 Na⁺). C, Plot of E_GABA determined after recovery in ACSF and subsequent recovery in 50 μm bumetanide. Individual experiments are shown as open circles connected by lines (mean ± SEM was calculated from 16 experiments). D, Plot of E_GABA after recovery in ACSF and Na⁺-free ASCF. Mean ± SEM was calculated from 12 experiments. E_GABA after recovery was significantly reduced (p < 0.001) by bumetanide and Na⁺-free ASCF. E, Effect of bumetanide and Na⁺-free conditions on [Cl⁻]_i. Error bars represent mean ± SEM of [Cl⁻]_i as calculated from E_GABA shown in C and D. The number of experiments is shown in the bars, and the dashed line indicates passive Cl⁻ distribution. F, Recovery of [Cl⁻]_i calculated from the values depicted in A. Recovery curves are aligned to a [Cl⁻]_i of 6.6 mm (for details, see Results).