Table 1

Parameters for inhibition of 4-aminopyridine-evokedl-[3H]glutamate and [14C]GABA release

Potency (IC50)Maximum Inhibition (Imax)
−Ca2++Ca2+−Ca2++Ca2+
%
[3H]Glutamate release
 Isoflurane1-a 0.39 ± 0.10 mM65 ± 8
 Propofol3.3 ± 2.2 μM17 ± 13 μM42 ± 654 ± 12
 Tetrodotoxin5.5 ± 3.4 nM14 ± 4 nM66 ± 285 ± 4
 Riluzole4.2 ± 7.9 μM1.2 ± 0.4 μM92 ± 1080 ± 5
[14C]GABA release
 Isoflurane0.48 ± 0.07 mM  (P = 0.48)43 ± 6  (P = 0.023)
 Isoflurane (0.1 mM 4 AP)0.28 ± 0.07 mM  (P = 0.65)31 ± 4  (P < 0.001)
 Propofol4.4 ± 1.2 μM (P = 0.96)39 ± 11 μM1-164  (P = 0.21)48 ± 4  (P = 0.99)54 ± 31  (P = 0.99)
 Tetrodotoxin14 ± 0.4 nM (P = 0.029)19 ± 0.5 nM1-170  (P = 0.26)81 ± 2  (P < 0.001) 57 ± 5  (P < 0.001)
 Riluzole4.6 ± 2.4 μM (P = 0.96)2.4 ± 3 μM  (P = 0.71)100 ± 28  (P = 0.79)52 ± 12  (P = 0.041)

Values were derived by fitting data to sigmoidal concentration effect-curves (variable slope). Data are shown as the mean ± S.E.M.

  • 1-a Data failed to fit curve.

  • Statistical significance between glutamate and GABA by unpairedt test (in parentheses; significant difference in italics); and between IC50 + Ca2+ and −Ca2+ by unpairedt test (

  • 1-164 P < 0.001;

  • 1-170 P < 0.001).