Measurements of airway surface liquid height and mucus transport by fluorescence microscopy, and of ion composition by X-ray microanalysis.

The respiratory tract is lined by a thin layer of fluid, the airway surface liquid (ASL), which plays a critical role in lung defense. The paper describes methods to determine the height of the ASL and corresponding mucus transport rates using fluorescent probes, and methods to determine the ionic composition of the ASL by X-ray microanalysis.