Fig. 2. Effect of midazolam (1 μM) on GABAergic miniature inhibitory postsynaptic currents (mIPSCs) in substantia gelatinosa (SG) neurons. (A ) Eight consecutive traces of GABAergic mIPSCs before (left ) and 2 min during (right ) the application of midazolam. (B ) Amplitude, frequency, and duration of GABAergic mIPSCs measured for 1 min under the action of midazolam, relative to those in the control (n = 7). Vertical bars show SD; *Significantly different from control, P < 0.01. (C ) Averaged traces of 174 and 200 GABAergic mIPSCs before and after the addition of midazolam, respectively; these are superimposed for comparison. (D ) Cumulative distributions of the amplitude (left ) and interevent interval (right ) of GABAergic mIPSCs, before (continuous line) and under (dotted line) the action of midazolam, which were obtained by analyzing 174 and 200 mIPSC events (which occurred for 30 s), respectively. Midazolam had no effect on both distributions of the amplitude and frequency (P > 0.4, Kolmogorov-Smirnov test). The mIPSCs were recorded in the presence of strychnine (2 μM), together with tetrodotoxin (0.5 μM), CNQX (20 μM), and APV (50 μM). V^H= 0 mV.