TABLE 1

Inhibition potencies of 4-aminopyridine-evoked l-[3H]glutamate and [14C]GABA release

Values were derived by fitting data to sigmoidal concentration effect-curves (see Materials and Methods). Statistical significance between glutamate and GABA (*, P < 0.05; **, P < 0.01; ***, P < 0.001) and between –Ca2+ and Ca2+-dependent release (††, P < 0.01; †††, P < 0.001) were calculated using logIC50 values by unpaired Student's t test.


Drug

Transmitter

Potency (IC50)
-Ca2+
+Ca2+
Ca2+-Dependent
Isoflurane Glutamate 0.58 ± 0.10 mM* 0.57 ± 0.04 mM*** 0.58 ± 0.06 mM***
GABA 0.26 ± 0.06 mM 0.78 ± 0.03 mM 1.06 ± 0.04 mM†††
Enflurane Glutamate 0.64 ± 0.12 mM** 0.67 ± 0.06 mM*** 0.72 ± 0.11 mM***
GABA 0.31 ± 0.05 mM 1.48 ± 0.14 mM 2.34 ± 0.29 mM†††
Halothane Glutamate 0.33 ± 0.04 mM 0.41 ± 0.04 mM*** 0.47 ± 0.06 mM*
GABA 0.34 ± 0.05 mM 0.59 ± 0.04 mM 0.76 ± 0.08 mM††
Tetrodotoxin Glutamate 20 ± 58 nM 18 ± 5.5 nM 18 ± 6.9 nM

GABA
29 ± 28 nM
20 ± 7.3 nM
15 ± 8.3 nM