Figure 4.

(a) BDZ-d inhibited both the rate and the amplitude of the opening of the GluA2Q_flip channels, shown in the representative whole-cell current traces from an HEK-293 cell obtained from the laser-pulse photolysis experiment. The upper trace (○) was the control (k_obs = 2079 s^–1; A = 0.74 nA), and the lower trace (□) contained 20 μM BDZ-d (k_obs = 1591 s^–1; A = 0.38 nA). The concentration of the photolytically released glutamate was estimated to be ∼100 μM in both cases. (b) Effect of BDZ-d on k_cl obtained at 100 μM of photolytically released glutamate and as a function of BDZ-d concentration. A K̅_I* of 57 ± 5 μM was determined using eq 2. (c) Effect of BDZ-d on k_op obtained at 300 μM of photolytically released glutamate and as a function of BDZ-d concentration. A K_I* of 66 ± 20 μM was determined using eq 3. (d) Effect of BDZ-d on the whole-cell current amplitude obtained from the laser-pulse photolysis measurement. A K_I of 18 ± 2 μM was determined at 100 μM of photolytically released glutamate (●); a K_I of 16 ± 1 μM was obtained at 300 μM of photolytically released glutamate (○).