The summary of single-channel kinetic analysis from the wild-type receptor under control conditions and in the presence of combinations of steroids. The mean durations (CT1-3) and relative contributions (fraction CT1-3) for the three closed-time components are shown. All data were obtained in the presence of 50 μM GABA to activate the channel. The control data (no steroids) are from Akk et al. (2005). Statistical analysis was carried out using analysis of variance with Bonferroni correction (Systat 7.0; Systat Software, Inc.). For etiocholanolone, ent-etiocholanolone, and 3α5βP, the significance level applies to comparison with no steroid (control) condition. For etiocholanolone + ent-etiocholanolone, the significance levels apply to comparison with control condition and to ent-etiocholanolone alone. For etiocholanolone + 3α5βP, the significance levels apply to comparison with control condition and to 3α5βP alone.
Steroid(s) | CT1 | Fraction CT1 | CT2 | Fraction CT2 | CT3 | Fraction CT3 | n |
|---|---|---|---|---|---|---|---|
| ms | ms | ms | |||||
| None | 0.17 ± 0.02 | 0.57 ± 0.06 | 1.7 ± 0.7 | 0.14 ± 0.05 | 13.5 ± 5.3 | 0.29 ± 0.02 | 8 |
| 10 μM etiocholanolone | 0.17 ± 0.02 | 0.51 ± 0.07 | 2.1 ± 0.7 | 0.23 ± 0.07 | 16.0 ± 3.5 | 0.26 ± 0.05† | 6 |
| 10 μM ent-etiocholanolone | 0.15 ± 0.01 | 0.59 ± 0.09 | 1.7 ± 0.6 | 0.28 ± 0.03 | 17.7 ± 6.3 | 0.13 ± 0.08*** | 6 |
| 10 μM etiocholanolone + 10 μM ent-etiocholanolone | 0.15 ± 0.04 | 0.68 ± 0.05 | 1.3 ± 0.4 | 0.25 ± 0.06 | 14.0 ± 7.0 | 0.07 ± 0.01***† | 5 |
| 200 nM 3α5βP | 0.16 ± 0.02 | 0.60 ± 0.04 | 1.5 ± 0.3 | 0.29 ± 0.02 | 8.7 ± 1.6 | 0.11 ± 0.04*** | 4 |
| 10 μM etiocholanolone + 200 nM 3α5βP | 0.15 ± 0.02 | 0.55 ± 0.10 | 1.6 ± 0.4 | 0.31 ± 0.06 | 16.3 ± 4.6 | 0.14 ± 0.09***† | 4 |