The Ova mouse model of acute allergic asthma is a well-established asthma model. Mice or Brown-Norway rats will be sensitized systemically and challenged inhalationally with ovalbumin. During the challenge the early airway response (EAR) and 4-5 h later the late airway response (LAR) can be registered by lung function measurement. After 24 h or 48 h, using a second lung function measurement, the airway hyperresponsiveness will be registered followed by a bronchoalveolar lavage with immunologic and histologic analyses of the inflammatory allergic response. Exact individual dosing during inhalation provocation or drug treatments will be achieved by means of a computerized feedback dose-control system.