Table 1.
Effect of anticholinergics on airways hyperresponsiveness in asthmaa.
| Provocation | Effect |
|---|---|
| Beta blockers | Abolished response |
| Bradykinin | 5-fold increase in PD35 |
| Capsaicin | 60% reduction in response |
| Distilled water | 50–100% reduction in response |
| Exercise | 30% reduction in response |
| Histamine | 10-fold increase in PC100 SRaw |
| Hyperpnea | Abolished response in children |
| Prostaglandin D2 | 12- to 22-fold increase in PC20 |
| Psychogenic stimulation | Abolished response |
| Reflux or esophageal acidification | Abolished response |
| Thromboxane A2 | 23-fold increase in PC20 |
aAnticholinergics used were either ipratropium bromide or atropine delivered via aerosol. Results reviewed in detail elsewhere [35]. Abbreviations: PC20 and PD35: provocative concentration (or dose) of agonist producing a 20% or 35% decrease, respectively, in forced expiratory volume in 1 sec (FEV1); PC100 SRaw: provocative concentration of agonist producing a 100% increase in specific airways resistance.