Distinct Action of Flavonoids, Myricetin and Quercetin, on Epithelial Cl− Secretion : Useful Tools as Regulators of Cl− Secretion

Abstract EN

Epithelial Cl− secretion plays important roles in water secretion preventing bacterial/viral infection and regulation of body fluid.

We previously suggested that quercetin would be a useful compound for maintaining epithelial Cl− secretion at a moderate level irrespective of cAMP-induced stimulation.

However, we need a compound that stimulates epithelial Cl− secretion even under cAMP-stimulated conditions, since in some cases epithelial Cl− secretion is not large enough even under cAMP-stimulated conditions.

We demonstrated that quercetin and myricetin, flavonoids, stimulated epithelial Cl− secretion under basal conditions in epithelial A6 cells.

We used forskolin, which activates adenylyl cyclase increasing cytosolic cAMP concentrations, to study the effects of quercetin and myricetin on cAMP-stimulated epithelial Cl− secretion.

In the presence of forskolin, quercetin diminished epithelial Cl− secretion to a level similar to that with quercetin alone without forskolin.

Conversely, myricetin further stimulated epithelial Cl− secretion even under forskolin-stimulated conditions.

This suggests that the action of myricetin is via a cAMP-independent pathway.

Therefore, myricetin may be a potentially useful compound to increase epithelial Cl− secretion under cAMP-stimulated conditions.

In conclusion, myricetin would be a useful compound for prevention from bacterial/viral infection even under conditions that the amount of water secretion driven by cAMP-stimulated epithelial Cl− secretion is insufficient.