Pathophysiology of bronchial hypersecretion.

Density gradient ultracentrifugation has been used to analyse the lavage from the proximal intrapulmonary bronchi of normal human volunteers and of dogs. The secretion from explants of canine trachea and human lobar bronchi has been examined under basal conditions and after stimulation by secretagogues. Mucus from the hypersecretory airways has been obtained from tracheostomized patients and from a canine model of chronic bronchitis produced by exposure to SO2 gas. No macromolecule of density gradient typical of an epithelial glycoprotein was recovered from normal basal secretions: the glycoconjugate recovered was of higher density and has sugars typical of a proteoglycan. The explant produced typical epithelial glycoprotein if stimulated. As volume of secretion increases, macromolecular yield does also, both of epithelial glycoprotein and of a number of lipids that are synthesised by the airway and which are different from alveolar lipids.