Table 3.
Effects of several acetylcholine receptor antagonists on Isc induced by propionylcholine across mucosal–submucosal as well as mucosal preparations of rat distal colon
| Blocker | PCh ( − blocker) | PCh (+ blocker)h | n | PCh ( − blocker) | PCh (+ blocker) | n |
|---|---|---|---|---|---|---|
| ΔI sc (μEq·h−1·cm−2) | ||||||
| Mucosa–submucosa | Mucosa | |||||
| ACh receptors | ||||||
| Hexamethonium and atropine | 4.43 ± 0.66 | 0.64 ± 0.22a | 8/7 | 10.30 ± 1.11 | 0.15 ± 0.02a | 6/7 |
| Nicotinic acetylcholine receptors | ||||||
| Hexamethonium | 2.61 ± 0.83 | 5.72 ± 1.19 | 6 | 9.49 ± 1.75 | 6.34 ± 1.38 | 6 |
| Mecamylamine | 5.02 ± 0.45 | 5.39 ± 1.16 | 6 | 9.63 ± 1.27 | 5.22 ± 0.78a | 6 |
| Muscarinic acetylcholine receptors | ||||||
| Atropine | 9.97 ± 1.88 | 3.10 ± 0.66a | 6 | 10.82 ± 1.37 | 1.60 ± 0.44a | 6/7 |
| M1 acetylcholine receptors | ||||||
| Telenzepine | 4.55 ± 1.01 | 2.78 ± 0.35 | 6 | 12.16 ± 1.62 | 3.79 ± 0.87a | 6 |
| Pirenzepine | 4.28 ± 0.90 | 1.69 ± 0.21a | 7 | 9.68 ± 1.45 | 4.31 ± 0.52a | 6/7 |
| M3 acetylcholine receptors | ||||||
| Darifenacine | 6.84 ± 1.68 | 1.41 ± 0.41a | 6 | 11.21 ± 1.46 | 2.45 ± 0.44a | 6 |
| J104129 | 4.30 ± 0.49 | 0.39 ± 0.10a | 6 | 8.85 ± 1.82 | 0.47 ± 0.18a | 6 |
The response to propionylcholine (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 as follows: hexamethonium (100 μM ), mecamylamine (10 μM ), atropine (1 μM), telenzepine (0.1 μM), pirenezepine (1 μM), darifenacine (10 μM) and J104129 (5 μM). All inhibitors were administered to the serosal side. Values are given as increase in I sc (ΔI sc) above baseline just before administration of propionylcholine and are means ± SEM.
P < 0.05 versus response evoked by propionylcholine in the respective control series. PCh, propionylcholine.