Abstract
Ambroxol is often used as an expectorant in various lung diseases. However, it is unclear how ambroxol acts on bronchial epithelial cells. To clarify the action of ambroxol, we studied the effect of ambroxol on the ion transport in human Calu-3 cells, a human submucosal serous cell line, measuring the transepithelial short circuit current across monolayers of Calu-3 cells. Ambroxol of 100 micro-M applied to the both apical and basolateral sides diminished the terbutaline (a beta2-adrenergic agonist)-stimulated chloride secretion without any decreases in the apical chloride channel conductance. On the other hand, ambroxol had no effects on the chloride secretion or the apical chloride channel conductance under the basal (unstimulated) condition. Ambroxol had no major action on the epithelial Na+ channel (ENaC) and its-mediated Na+ absorption. These results indicate that: 1) ambroxol acts on the cAMP-stimulated Na+/K+/2Cl- cotransporter in Calu-3 cells, and 2) ambroxol has more powerful action than the adrenergic agonist action on the cAMP-stimulated Na+/K+/2Cl- cotransporter, leading the chloride secretion to a moderately stimulated level from a hyper-stimulated level. Supported by JSPS 15659052 (YM), 15590189 (NN), 15790120 (HM), MHLW 14C-5. [Jpn J Physiol 54 Suppl:S85 (2004)]
