 High-resolution immunofluorescence studies revealed that in the respiratory tract and the female reproductive tract, ENaC is located along the entire length of cilia that cover the surface of multi-ciliated cells.Hence, in these epithelia with motile cilia, ENaC functions as a regulator of the osmolarity of the periciliary fluid, and its function is essential to maintain fluid volume at a depth necessary for the motility of the cilia.In the respiratory tract this movement is essential for clearing mucosal surface, and in the female reproductive tract, motility of the cilia is essential for the movement of oocytes.