Hypertonic Saline in Treatment of Pulmonary Disease in Cystic Fibrosis

Figure 3

Effect of hypertonic saline on the airway surface liquid (ASL) in CF. (a) In healthy airway epithelia, CFTR is intact and plays a vital role in regulating hydration of the ASL that consists of the periciliary layer (PCL) and the mucus layer. (b) Due to defective CFTR in CF, Cl⁻ secretion is impaired and Na⁺ absorption through ENaC is upregulated resulting in dehydration of the ASL with thick mucus accumulating and causing the PCL to collapse. (c) Treatment with hypertonic saline is proposed to reduce mucus viscosity and aids its clearance by various mechanisms. The high salt concentration encourages osmosis of water into the ASL and thereby rehydrates the mucus and partially restores the PCL allowing for easier clearance of mucus. Additionally, the high ionic strength weakens ionic bonds between negatively charged GAGs and thus reduces the viscosity of the mucus.

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