Figure 3.

(A) Difference records obtained by subtraction of currents recorded in the absence of glutamate from records in the presence of 100 μM l-glutamate in oocytes expressing the mutant Y403F transporter. Pulses are 100 ms in duration in 20-mV increments to potentials between −120 mV and +40 mV from a holding potential of −30 mV. Dashed line shows zero current. (B) Same protocol and oocyte as in A showing shift in the reversal potential from −30 mV (E_Cl) to approximately −60 mV after substitution of 20 mM Cl with NO₃. (C) Summary of voltage dependence of glutamate-induced currents (mean ± SEM, n = 4) recorded in 100 mM NaCl (squares) or 80 mM NaCl/20 mM NaNO₃.