Fig. 3. Bupivacaine inhibits the response to exogenous N -methyl-d-aspartate (NMDA) in substantia gelatinosa neurons in different pH conditions. (A and B ) Bupivacaine (Bup; 2 mm) reversibly inhibited NMDA-induced currents under pH 7.0 or pH 8.0 conditions. (C ) The relative amplitudes were 43 ± 13% of the control level at pH 7.0 and 58 ± 21% at pH 8.0. Comparison of the inhibitory effects of bupivacaine among the three groups (pH 7.0, 7.4, and 8.0) showed that the levels of inhibition were the same (P = 0.30, one-way analysis of variance). *P < 0.01.