Open durations of wild-type and mutant muscle nAChR activated by ACh and GABA
Single-channel recordings were performed from cells expressing muscle wild-type receptors or receptors containing the indicated mutant subunit. Open duration components were obtained from the open time histograms. Data are shown as mean ± S.D. for at least three recordings for each condition. For αY190F, single-channel activity in the presence of GABA was not detected in 14 different patches from GFP-transfected cells (green cells).
| Receptor | Agonist | μM | Open 1 (ms) (Relative Area) | Open 2 (ms) (Relative Area) |
|---|---|---|---|---|
| Wild-type | ACh | 1 | 0.99 ± 0.10 (0.70 ± 0.12) | 0.24 ± 0.07 (0.30 ± 0.13) |
| GABA | 1 | 0.76 ± 0.12 (0.31 ± 0.04) | 0.10 ± 0.03 (0.69 ± 0.04) | |
| αY190F | ACh | 60 | 0.58 ± 0.17 (0.11 ± 0.06) | 0.19 ± 0.05 (0.89 ± 0.06) |
| GABA | 1–10,000 | nd | nd | |
| αG153S | ACh | 1 | 3.76 ± 0.29 (0.67 ± 0.07) | 0.36 ± 0.04 (0.32 ± 0.07) |
| GABA | 1 | 1.68 ± 0.40 (0.39 ± 0.157) | 0.18 ± 0.02 (0.60 ± 0.157) | |
| εG57Q | ACh | 1 | 0.88 ± 0.0 (0.18 ± 0.12) | 0.32 ± 0.03 (0.82 ± 0.12) |
| GABA | 1000 | 1.91 ± 0.33 (0.11 ± 0.01) | 0.24 ± 0.03 (0.89 ± 0.01) | |
| δD57Q | ACh | 1 | 1.18 ± 0.25 (0.67 ± 0.08) | 0.32 ± 0.06 (0.33 ± 0.08) |
| GABA | 1000 | 1.55 ± 0.59 (0.06 ± 0.02) | 0.16 ± 0.02 (0.93 ± 0.01) |
nd, not detected.