Study to Investigate the Effect of Inhaled Tiotropium Bromide on Neurokinin-A Induced Bronchoconstriction in Patients With Mild-to-moderate Asthma

Inclusion Criteria: * Informed consent * Male or female, at least 18 years old * Documented medical history of asthma (diagnosis at least 6 months ago) * Non-smoker or at least stopped for 1 year (in case smoked earlier: maximum of 10 pack-years) * Able to conduct a technically acceptable spirometry, methacholine and neurokinin-A provocation test. * At visit 1: PC20 methacholine ≤ 8 mg/ml AND ≤ 3.3x10-7 mol/ml for the neurokinin-A provocation test. * At visit 1: forced expiratory value in one second \>= 80% of the predicted value. * Female subjects may not get pregnant and should be using adequate contraception. Exclusion Criteria: * Airway infection within 6 weeks prior to first study visit. * Other respiratory diseases (eg COPD, lung cancer, etc.) * Participating in another clinical trial. * Clinically relevant systemic diseases, other than asthma. * Clinically significant laboratory deviations. * Alcohol or drug abuse. * Female subjects who are lactating.