Inhibition of [3H](−)-MQNB binding to HM2-B10 and M2LKB2-2 cells by muscarinic drugs
| Drug | HM2-B10 cells (human) | M2LKB2-2 cells (rat) | ||
|---|---|---|---|---|
| Ki | nH | Ki | nH | |
| nM | nM | |||
| Agonist | ||||
| 1. Oxotremorine | 235 (214-254) | 1.4 ± 0.5 | 290 (188-367) | 1.7 ± 0.6 |
| 2. Acetylcholine | 347 (318-399) | 1.3 ± 0.4 | 430 (352-640) | 1.1 ± 0.4 |
| 3. Carbachol | 1820 (1740-1930) | 1.1 ± 0.3 | 2060 (1880-2350) | 1.2 ± 0.4 |
| Antagonist | ||||
| 4. Atropine | 0.63 (0.5-0.7) | 0.9 ± 0.3 | 0.87 (0.8-0.96) | 1.0 ± 0.3 |
| 5. Dexetimide | 1.2 (0.8-1.8) | 1.0 ± 0.3 | 1.5 (1.3-2.1) | 0.8 ± 0.2 |
| 6. 4-DAMP | 4.7 (4.1-5.6) | 0.9 ± 0.3 | 6.7 (4.5-9.6) | 1.2 ± 0.4 |
| 7. Himbacine | 12 (9.2-17) | 0.9 ± 0.3 | 14 (10-19) | 1.0 ± 0.3 |
| 8. Methoctramine | 42 (38-49) | 1.5 ± 0.4 | 49 (39-63) | 1.7 ± 0.5 |
| 9. AF-DX 116 | 67 (54-80) | 1.1 ± 0.3 | 50 (20-90) | 1.3 ± 0.3 |
| 10. HHSiD | 153 (110-190) | 1.1 ± 0.3 | 174 (130-215) | 1.0 ± 0.3 |
| 11. Pirenzepine | 374 (340-400) | 0.9 ± 0.3 | 442 (370-550) | 0.8 ± 0.3 |
| 12. Gallamine | 1730 (1240-2080) | 0.7 ± 0.2 | 2610 (2600-2670) | 0.9 ± 0.3 |
| 13. Levetimide | 9060 (4640-13,440) | 0.9 ± 0.3 | 15,500 (6670-27,800) | 1.1 ± 0.3 |
The intact cells were incubated with [3H](−)-MQNB (final concentrations, 0.29-0.43 nM) and 10 concentrations of selected agonists or antagonists. IC50 values and Hill coefficients (nH) are analyzed using a nonlinear least-squares regression analysis based on three separate experiments done in duplicate. Values are expressed as the geometric mean with the range in parentheses for Ki and arithmetic mean ± S.E.M. for the Hill coefficient.