Figure 4.

Ionic dependence of EAAT5-mediated currents. (A) Steady-state current elicited by 100 μM l-glutamate (circles) is abolished when external sodium is replaced with NMDG (squares). Data are the average of five cells. (B) Steady-state current elicited by 100 μM l-glutamate in normal chloride (circles) or when external chloride was replaced with gluconate (squares). Removal of external chloride ions blocks outward current at positive potentials and has no effect at negative potentials. Data are the average of five cells. (C) Steady-state current elicited by 100 μM l-glutamate in normal oocytes (circles) or in oocytes dialyzed in chloride-free solution for >48 h (squares). No currents are seen in oocytes dialyzed to remove chloride ions. Data are the average of 10 cells for each condition. (D) Steady-state current elicited by 100 μM l-glutamate in normal chloride (circles) or when most external chloride was replaced with nitrate (squares). l-glutamate elicited current in nitrate produces a large outward current. Data are the average of six cells. All error bars represent SEM. Error bars smaller than the symbols are not shown.