Deep breaths and airway closure in asthma

INTERVENTION: Poractant alfa, 120mg delivered by aerosolization of a 50mg/ml suspension in 0.9% normal saline, on two occasions administered 30 minutes before bronchial challenge with methacholine chloride. CONDITION: Asthma PRIMARY OUTCOME: The fall in the forced expiratory volume in one second, with and without deep inspirations. SECONDARY OUTCOME: The bronchoprotective effect of deep inspiration, measured by the difference in response between tests with and without deep inspirations, after active and control treatments. INCLUSION CRITERIA: Asthma, defined by previous doctor diagnosis and current symptoms or regular therapyNon‐asthmatic controls with no history of asthma or other chronic respiratory disease.