Relation of smoking to immunoreactive endothelin in the bronchiolar epithelial cells.

BACKGROUND Endothelin is a potent bronchoconstrictor which appears to be important in asthma. To ascertain whether cigarette smoking is associated with any alteration in the proportion of bronchiolar epithelial cells which express endothelin immunoreactivity, the airways in the lungs of non-smokers and smokers were analysed. Since an increase in immunoreactivity has been found in the bronchial epithelial cells of asthmatic subjects, cigarette smokers with and without evidence of airway hyperresponsiveness were also selected. METHODS A point counting method which examined the proportion of endothelin immunoreactive epithelial cells in membranous and respiratory bronchioles was used. RESULTS Neither smoking itself nor evidence of airway hyperresponsiveness altered the percentage of endothelin immunoreactive epithelial cells in the membraneous and respiratory bronchioles. CONCLUSIONS Cigarette smoke does not induce endothelin production in bronchiolar epithelial cells, and the airway hyperresponsiveness seen in some patients with lung disease induced by cigarette smoking is not related to exaggerated endothelin production in epithelial cells.