Summary of the characteristics of modulators of GABA responses in the wild-type and mutant α1β2/3γ2S GABAARs expressed in Xenopus oocytes Changes in EC5 GABA in the presence of drug are given as percentage of mean ± S.E.M. for each receptor. The direct responses to etomidate are given as percentage of the maximal GABA response. The number of oocytes is given in parentheses.
EC5 GABA + Drug | α1β2γ2S | α1(S270H; L277A)β2γ2S | α1β3γ2S | α1(S270H; L277A)β3γ2S |
|---|---|---|---|---|
| Isoflurane (0.30 mM) | 283 ± 28 (7) | 148 ± 9*** (8) | 352 ± 25 (5) | 153 ± 18*** (6) |
| Butanol (11 mM) | 184 ± 16 (8) | 29 ± 7 *** (8) | Not tested | Not tested |
| Zn2+ (10 μM) | -27.5 ± 4.6 (21) | -11.9 ± 2.9* (22) | -26.5 ± 1.6 (17) | -25.2 ± 1.3 (18) |
| Flunitrazepam (1 μM) | 89 ± 19 (15) | 108 ± 8 (16) | 230 ± 22 (5) | 226 ± 10 (6) |
| Pentobarbital (50 μM) | 621 ± 75 (6) | 425 ± 42* (6) | 803 ± 67 (5) | 533 ± 23** (6) |
| Etomidate (1 μM) | 368 ± 37 (8) | 165 ± 17*** (8) | 338 ± 29 (5) | 165 ± 14*** (6) |
| Drug alone | ||||
| Etomidate (10 μM) | 23.6 ± 9.4 (8) | 19.8 ± 5.2 (8) | 9.1 ± 2.2 (7) | 2.9 ± 0.7* (8) |
Statistical significance was assessed using Student's t test. *p < 0.05, **p < 0.005, and ***p < 0.0005 compared with the corresponding wild-type receptor