Regulation of Na+ and Cl- transport and mucous gland secretion in airway epithelium.

Ussing's short-circuit technique was applied to canine airway epithelium in vitrol and a net flux of Cl- towards the airway lumen was demonstrated, with a smaller net flux of Na+ in the opposite direction. Furosemide decreased and acetylcholine, terbutaline, and histamine increased net ion transport towards the airway lumen. Associated changes in water content in the airway lumen could affect mucociliary clearance, and therefore inhibition of ion transport may play a role in disease states. To study secretions from submucosal glands in vivo, two techniques were used to identify the duct openings in the exposed canine tracheal epithelium. (a) The exposed mucosal surface was coated with powdered tantalum; accumulated secretions produced elevations under which the duct openings were located. (b) A vital dye (0.1% Neutral red) was placed on the exposed mucosal surface; the dye stained the duct openings. With these techniques, the innervation of the submucosal glands and the autonomic regulation of their secretions were studied. Micropuncture techniques were used to sample the secretions from the glands and ducts.