Lack of airway response to nasal irritation in normal and asthmatic subjects

Twenty two subjects (10 normals, nine asthmatics and three who had suggestive histories for asthma but normal bronchial histamine challenges) underwent nasal challenges with logarithmic incremental doses of histamine or saline on alternate days. Nasal resistance (measured by posterior rhinometry), and forced expiratory volume in one second (FEV1) were assessed after each dose of nasal histamine or placebo. After each nasal challenge (maximum nasal dose of 250 micrograms of histamine or doubling of nasal resistance) bronchial responsiveness was measured with a bronchial histamine challenge. Despite significant changes in nasal resistance with nasal histamine (p less than 0.01) there was no significant change in the forced expiratory volume in one second, or in bronchial responsiveness. We were unable to demonstrate nasobronchial reflexes initiated by acute irritation of the nasal mucosa with histamine in either normal subjects or in those with mild to moderate asthma.