A, Current traces recorded at −70 mV show that application of tolbutamide (100 μM) increased the amplitude of inward currents evoked by NMDA (20 μM) in an STN neuron. B, Summarized NMDA I-V plots for STN neurons show that tolbutamide (100 μM) significantly altered the I-V plot compared to control (P < 0.05, two-way repeated measures ANOVA). Asterisks indicate significant differences at specific test potentials (P < 0.05, Holm-Sidak pairwise comparison test). C, In an SNC neuron, tolbutamide (100 μM) has no effect on current evoked by NMDA (10 μM) recorded at −60 mV. D, Summarized data show that tolbutamide failed to modify voltage-dependent NMDA currents in SNC neurons (n = 7).