Effects of pulmonary inhalation of water and histamine aerosols on nasal airflow resistance in man.

We investigated the effect of aerosols inhaled into the lungs on nasal airflow resistance (Rnaw) using a constant inflow pressure method with measured airflow. Isotonic saline and water aerosols produced no immediate significant change in Rnaw and forced expired volume in 1 s (FEV1); however, water gradually decreased FEV1 and increased Rnaw, the response being maximal 10-15 min after provocation. Histamine aerosol significantly increased Rnaw in healthy subjects, asthmatics and asthmatics with allergic rhinitis. There was also a corresponding decrease in FEV1. The increase in Rnaw and the decrease in FEV1 were reversed by inhalation of terbutaline (10 mg . ml-1). Similarly, terbutaline in patients with mild asthmatic attacks decreased Rnaw and increased FEV1. Since terbutaline applied locally into the nose is known to increase Rnaw, we conclude that lung provocation can increase nasal Rnaw, presumably via nervous pathways.