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.