Signal transduction of mucous secretion by bronchial gland cells

Bronchial glands, which consist of mucous and serous cells, are abundant in human airways, playing a major role in the airway secretion. Cl- secretion is accompanied by water transport to the lumen in the acinar cells of bron chial glands. Agonists that increase [Ca2+]i induce the Cl- secretion in br onchial glands. Ca2+ release from a IP3-sensitive Ca2+ pool at the apical p ortion stimulates and opens Ca2+-sensitive Cl- channels at the apical membr ane, producing Cl- secretion in bronchial glands. K+ channels at the basola teral membranes are Ca2+-sensitive and activated by Ca2+ release from a cAD Pribose-sensitive Ca2+ pool, maintaining the Cl- secretion in bronchial gla nds. Further, cADP ribose in concert with IP3 induce [Ca2+']i oscillation, inducing Cl- secretion in bronchial glands. Some tyrosine kinases are invol ved in the Cl- secretion in bronchial glands. Mucous and serous cells in br onchial glands take part in mucin secretion and the secretion of defensive substances (glycoconjugates), respectively. [Ca2+]i oscillations are shown to play a central role in the exocytosis of secretory granules in serous ce lls of bronchial glands. Other signal transductions of mucin and glycoconju gates in airway gland cells remain to be studied, although agonists which i ncrease [cAMP]i are also well known to induce mucin and glycoconjugate secr etion from airway glands. (C) 2000 Elsevier Science Inc. All rights reserve d.