[Regulation and pathophysiology of airway secretion]

Although excessive production of sputum is one of the characteristic features of acute and chronic respiratory infections, bronchiectasis, diffuse panbronchiolitis, chronic bronchitis and asthma, pathophysiological mechanisms underlying airway hypersecretion remain uncertain. The increase in intraluminal mucus may lead to impairment of airway mucociliary clearance and deterioration of bronchial obstruction. Airway surface fluid is composed of mucus glycoprotein released from submucosal glands and goblet cells and water from airway epithelial cells, and the secretory function can be regulated by autonomic nervous system and a variety of chemical mediators. It is thus important to select mucoregulating drugs after understanding the mechanisms of hypersecretion and impaired mucociliary transport under individual conditions.