Potency of the test compounds to retard allosterically the dissociation of [3H]NMS from M2 receptors in porcine heart homogenates and affinity of the test compounds to displace [3H]dimethyl-W84 binding (0.3 nm) measured in the presence of 1 μm NMS under otherwise identical conditions
| Dimethyl-W84 | Alcuronium | W84 | Gallamine | |
|---|---|---|---|---|
| [3H]NMS dissociation | ||||
| pEC50,diss | 8.51 ± 0.02 | 8.40 ± 0.051-a | 7.72 ± 0.041-a | 6.74 ± 0.031-a |
| n H | −1.0 | −1.21-a | −1.11-a | −1.11-a |
| [3H]Dimethyl-W84 binding | ||||
| pK i, high | 8.741-b ± 0.09 | 8.62 ± 0.23 | 7.83 ± 0.19 | 6.72 ± 0.08 |
| pK i, low | 4.431-b ± 0.08 | 3.94 ± 0.16 | 4.10 ± 0.09 | 4.03 ± 0.04 |
| Capacityhigh | 0.31 ± 0.04 | 0.31 ± 0.08 | 0.37 ± 0.04 | 0.31 ± 0.09 |
pEC50,diss, concentration reducing the apparent rate constant k −1 of [3H]NMS dissociation to 50% of the control value; n H, slope factor of the curve (n H values were not significantly different from unity; partial F-test, p > 0.05); pK i, high, pK i, low, −log values of the inhibition constant K i to reduce saturable high and low affinity binding of [3H]dimethyl-W84, respectively; capacity, high affinity saturable [3H]dimethyl-W84 binding expressed as a fraction of total saturable binding at 0.3 nm [3H]dimethyl-W84. Given are mean ± standard error values of four to eight independent experiments.
↵1-a Data from Tränkle et al. (1996).
↵1-b Values indicate the pK D.