Figure 2. Sensitivity of nocifensive reflex facilitation to drugs that interfere with the GABA^Areceptor-mediated anionic gradient shift. The figures show the mean change +/− SD in hind paw withdrawal latency during 180 min after pentobarbital injection. Nocifensive reflex enhancement by pentobarbital was blocked by (A) Acetazolamide, 50 and 100 mg/kg (six rats per group)(F = 17.69, P < 0.001, *P < 0.05 vs. vehicle/pentobarbital and saline/saline) and (B) amiloride, 100 mg/kg (five rats in amiloride-treated animals, six animals in the vehicle/pentobarbital group)(F = 32.78, P < 0.001), *P < 0.05 vs vehicle/pentobarbital). ns = not significantly different.