The effect of serotonin on airway transepithelial sodium ion pathways.

The action of serotonin on ionic transport processes in the airways was revealed in a study of the isolated rabbit tracheal wall mounted in a Ussing apparatus. It was shown that the transepithelial electrical potential difference of the tissue was hyperpolarized transiently after mechanical stimulation by means of gentle rinsing of its mucosal side. This hyperpolarization was greatly influenced by the addition of serotonin and/or ambroxol to the stimulation (rinsing) fluid. By means of selective blocking of ion transport transepithelial pathways with amiloride and/or bumetanide, the effects of serotonin and/or ambroxol on the hyperpolarization after mechanical stimulation could be explained as changes of sodium ion currents. The importance of stimulated ionic currents for airway clearance and for the efficacy of drugs acting on airways is postulated.