Table 4.
Effects of acetylcholine receptor antagonists on Isc induced by butyrylcholine across mucosal–submucosal or mucosal preparations of rat distal colon
| Blocker | BCh ( − blocker) | BCh (+ blocker) | n | BCh (+ blocker) | BCh ( − blocker) | n |
|---|---|---|---|---|---|---|
| ΔIsc ( μEq·h−1·cm−2) | ||||||
| Mucosa–submucosa | Mucosa | |||||
| ACh receptors | ||||||
| Hexamethonium and atropine | 5.11 ± 1.10 | 1.17 ± 0.48a | 6 | 7.50 ± 1.22 | 0.26 ± 0.05 | 6 |
| Nicotinic acetylcholine receptors | ||||||
| Hexamethonium | 3.67 ± 0.58 | 2.39 ± 0.71 | 8 | 5.10 ± 1.13 | 1.51 ± 0.19a | 5/6 |
| Mecamylamine | 5.18 ± 0.81 | 0.53 ± 0.13a | 6 | 6.93 ± 1.65 | 1.30 ± 0.24a | 5/6 |
| Muscarinic acetylcholine receptors | ||||||
| Atropine | 8.63 ± 2.30 | 2.96 ± 0.74a | 8/7 | 10.24 ± 1.87 | 3.44 ± 0.37a | 6 |
| M1 acetylcholine receptors | ||||||
| Telenzepine | 3.99 ± 0.71 | 4.00 ± 1.22 | 7 | 8.59 ± 1.67 | 6.61 ± 1.13 | 6/7 |
| Pirenzepine | 5.92 ± 0.80 | 3.17 ± 0.55a | 7 | 9.74 ± 1.08 | 6.21 ± 0.90a | 6 |
| M3 acetylcholine receptors | ||||||
| Darifenacine | 5.22 ± 0.46 | 2.76 ± 0.75a | 7 | 9.50 ± 1.59 | 3.07 ± 0.53a | 6 |
| J104129 | 3.28 ± 0.83 | 0.43 ± 0.16a | 7 | 6.43 ± 1.51 | 0.40 ± 0.06a | 6/7 |
The response to butyrylcholine (500 μM at the serosal side) was either tested under control conditions, that is, in the absence of any inhibitor (− blocker), or in the presence of different inhibitors of acetylcholine receptors (+ blocker). Inhibitors used were: hexamethonium (100 μM), mecamylamine (10 μM ), atropine (1 μM), telenzepine (0.1 μM), pirenezepine (1 μM), darifenacine (1 μM) and J104129 (5 μM). All inhibitors were administered to the serosal side. Values are given as increase in I sc (ΔIsc) above baseline just before administration of butyrylcholine and are means ± SEM.
P < 0.05 versus response evoked by butyrylcholine in the respective control series. BCh, butyrylcholine.