Endothelin stimulates ciliary beat frequency and chloride secretion in canine cultured tracheal epithelium

Endothelin, an endothelium-derived vasoconstrictor peptide, has recently been reported to exist in airway epithelial cells. To elucidate a possible role of endothelin on epithelial functions, we studied the effects of this peptide on ciliary beat frequency (CBF) and electrical properties of canine cultured tracheal epithelium by a microphoto-oscillation method and Ussing's short-circuited technique, respectively. Endothelin dose-dependently increased CBF, the maximal increase above the baseline value and EC50 being 32.3 +/- 4.0% (P less than 0.001) and 3 nM, respectively. This effect was moderately attenuated by pretreatment of cells with indomethacin and greatly reduced by Ca2(+)-free medium. Addition of endothelin (10(-6) M) to the mucosal bath of Ussing chamber increased short-circuit current from 5.1 +/- 1.2 to 9.4 +/- 1.7 microA/cm2 (P less than 0.05) and potential difference from 2.9 +/- 0.4 to 5.0 +/- 0.9 mV (P less than 0.05), an effect that was inhibited by indomethacin or Ca2(+)-deficiency and was abolished by the Cl transport inhibitor bumetanide or substitution of Cl with iodide in the medium. These results indicate that endothelin stimulates ciliary motility and Cl secretion probably through an increase in cytosolic Ca2+ and partially a prostaglandin synthesis in canine tracheal epithelium, and suggest that this peptide might play a role in modulating airway mucociliary transport functions.