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. Author manuscript; available in PMC: 2015 Jul 1.
Published in final edited form as: Int J Biochem Cell Biol. 2014 Mar 13;0:130–135. doi: 10.1016/j.biocel.2014.03.002

Fig. 3.

Fig. 3

Schematic of airway surface liquid (transparent blue or red) above ciliated epithelial cells as depicted for normal lung (NL, left) and cystic fibrosis (CF, right) lung. The heterotrimeric epithelial sodium channel (ENaC) is rendered in orange, soluble SPLUNC1 in blue, and sodium ions as yellow. In normal (NL) airways, SPLUNC1 binds to and regulates ENaC, keeping a healthy level of sodium and water that allows cilia to function. In CF, low fluid pH prevents SPLUNC1’s regulation of ENaC, allowing isotonic removal of sodium and water by this channel, dehydrating the ASL and significantly reducing cilia function. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of the article.)