Fig. 4.

Effect of changing the reversal potential of the NMDAR current on blockade of NMDAR responses. A,B, Raw traces from two different cells illustrate the N₂O block with cesium loading (A) and choline loading (B). The horizontal bars over thetraces indicate the timing of drug applications.C, At a holding potential of −30 mV, the degree of N₂O block in cesium-loaded cells was not significantly different from the degree of block in cells loaded with choline (p > 0.3, unpaired t test;n = 14 cesium- and 11 choline-loaded cells). Choline loading changed the reversal potential of currents from ∼0 to approximately +50 mV. D, E, Rawtraces from two different cells illustrate the ketamine block in cesium- versus choline-filled cells. F, At a holding potential of −30 mV, the degree of ketamine (5 μm) block in choline-loaded cells was significantly greater than the block in cesium-loaded cells (p < 0.001, unpairedt test; n = 7 cesium- and 6 choline-loaded cells). G–I, A protocol similar to that shown in A–C and D–F was used except that Mg²⁺ was used as the antagonist and the holding potential was −60 mV. Raw traces in allpanels have been filtered at 10 Hz for display.