Table 3.
Functional affinities of various muscarinic receptor antagonists and β-adrenoceptor antagonists in human bronchus
| pKB | ||
|---|---|---|
| Segmental bronchus | Subsegmental bronchus | |
| Carbachol-induced contraction | ||
| Pirenzepine (1 µM) | 6.5 ± 0.4 | 6.6 ± 0.2 |
| AF-DX 116 (1 µM) | No inhibition | 6.1 ± 0.2 |
| Darifenacin (1 µM) | 8.4 ± 0.2 | 8.3 ± 0.1 |
| Isoprenaline-induced relaxation | ||
| ICI-89, 406 (0.1 µM) | No inhibition | No inhibition |
| ICI-118, 551 (0.1 µM) | 9.1 ± 0.3 | 8.3 ± 0.3 |
pKB values were calculated from the competition curves in the absence or presence of a single concentration of antagonist described in this table, according to concentration-ratio method (Furchgott, 1972).
Results represent mean ± SEM of 4–6 experiments.