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

Liquid secretion properties of airway submucosal glands

The tracheobronchial submucosal glands secrete liquid that is important for hydrating airway surfaces, supporting mucociliary transport, and serving as a fluid matrix for numerous secreted macromolecules including the gel-forming mucins. This review details the essential structural elements of airway glands and summarizes what is currently known regarding the ion transport processes responsible for producing the liquid component of gland secretion. Liquid secretion most likely arises from serous cells and is principally under neural control with muscarinic agonists, substance P, and vasoactive intestinal peptide (VIP) functioning as effective secretogogues. Liquid secretion is driven by the active transepithelial secretion of both Cl(-) and HCO(3)(-) and at least a portion of this process is mediated by the cystic fibrosis transmembrane conductance regulator (CFTR), which is highly expressed in glands. The potential role of submucosal glands in cystic fibrosis lung disease is discussed.

Histamine stimulation of mucociliary activity in the rabbit maxillary sinus

The in vivo effect of histamine on mucociliary activity in the rabbit maxillary sinus was investigated by injecting histamine into the maxillary artery and recording the responses with a photoelectric technique. Histamine stimulated the mucociliary activity dose-dependently in the dose range 10 to 1,000 micrograms/kg. The maximum response was 31.6% +/- 3.7% at a dose of 50 micrograms/kg. The histamine-induced stimulation of the mucociliary activity was characterized by a short latency with a peak response within 1 to 2 minutes and a slow decline lasting about 5 minutes. The response displayed tachyphylaxis. Cholinergic blockade with atropine did not affect the response to histamine. Blockade of H1 receptors with pyrilamine abolished the response to histamine, whereas blockade of H2 receptors with cimetidine was without effect. The H2 agonist dimaprit failed to stimulate the mucociliary activity. It is concluded that histamine stimulates the mucociliary activity in the rabbit maxillary sinus via H1 receptors.