Table 1
Equilibrium binding of tetracaine analogs to Torpedo nAChR NCA site
| Compound |  | Inhibition of [3H]HTX Binding KI | |||
|---|---|---|---|---|---|
| R1 | R2 | − | + Carb | +dTC | |
| μM | |||||
| I | C4H9NH- | -CH2CH2N(CH3)2 | 2.2 | 43 | 3.8 |
| II | C4H9NH- | -CH2CH2N(C2H5)2 | 0.4 | 5.7 | 0.5 |
| III | C4H9NH- | -CH2CH2CH2N(C2H5)2 | 0.3 | 2.6 | 0.2 |
| IV | C2H5O- | -CH2CH2N(C2H5)2 | 1.6 | 30 | 3.3 |
| V | NH2- | -CH2CH2N(C2H5)2 | 2000 | 1500 | 2000 |
| VI | H- |
| 0.8 | 55 | 2 |
Values of K I were determined as described in the text by nonlinear regression fit (n H = 1) of the observed concentration dependence of the inhibition of equilibrium binding at 20°C of [3H]HTX (20 nM) by TorpedonAChR-rich membranes (200 nM ACh sites) in the absence (−) or presence of 0.1 mM carbamylcholine (+ Carb) or d-tubocurarine (+dTC). Parameter uncertainties were 5 to 15% of K I.