In this issue of The Journal, Jayaraman and colleagues 2001 describe a novel technique to measure the osmolality of airway surface liquid (ASL) using fluorophore-encapsulated liposomes. As in a recent paper reporting measurements of ASL depth, salt concentration, and pH (Jayaraman et al. 2001), this group has once again exploited fluorescence microscopy in an innovative fashion to avoid the shortcomings of the traditional methods of harvesting ASL and analyzing its composition. As reported, ASL osmolality in the mouse was found to be 330 ± 36 mOsM (comparable to that of plasma), and no difference was found between wild-type and CF knockout mice. In addition to providing the beginning of a clear picture of ASL composition under normal conditions, these studies may have important implications for the pathogenesis of cystic fibrosis (CF) lung disease.
The use of fluorescent techniques to...
