Table 1.
Effects of Ba2+ on ACh evoked currents.
| mutant | Ach | EC50, μM | (n) | ACh Imax μA | Ba2+ efficacya |
| control | + 10 mM Ba2+ | ||||
| C115A/L247T | 1.8 ± 0.4 | 0.17 ± 0.02 | 4 | 6.9 | 0.1 |
| M37C | 2.0 ± 0.5 | 0.35 ± 0.12 | 4 | 0.92 | 0.2 |
| M40C | 7.7 ± 1.1 | 1.1 ± 0.1 | 5 | 3.0 | 0.1 |
| N52C | 2.6 ± 1.3 | ndb | 5 | 0.34 | 0.6 |
| E44C | 7.8 ± 0.4 | 10.1 ± 0.4 | 4 | 5.4 | 0.01 |
| N170Cc | 13 ± 1.7 | 2.1 ± 0.4 | 6 | 1.7 | 0.03 |
| E172Cc | 30 ± 2.7 | 50 ± 9.2 | 4 | 1.3 | 0.02 |
| M40C/E172Qc | 85 ± 6.2 | 134 ± 11 | 5 | 0.7 | 0.02 |
ACh dose-response measurements in the absence or presence of Ba2+. EC50 estimates are mean values ± SEM.
(a) Ba2+ efficacy is the fraction of maximal ACh-evoked current that is evoked by 10 mM Ba2+ in the absence of ACh. (b) nd: not determined because Ba2+ was a strong partial agonist. (c) Mutants studied using co-expression with human RIC-3 (Halevi et al., 2002).