Applications of electrophysiology in studies of ion transport by gut mucosa

The techniques described in this section all employ measurements of cell membrane potential as a central strategy in understanding fluxes of ions across the cell membrane. These techniques, used in complementary fashion, provide information about cell ion composition and cell volume [34]. In addition, they can be adapted to provide information about microenvironment (unstirred layers) lying near the epithelial surface [35], about cell membrane configurations, and about epithelial organization [24-27]. The central caveat, with respect to all of these methodologies, is that they are used best not in isolation. Studies using one electrophysiologic technique are validated by studies using complementary techniques, and in conjunction with information from morphologic studies, from dynamic studies of membrane function and from nonelectrophysiologic approaches (e.g., fluorescent dyes to complement electrode measurements). Such multidimensional approaches are necessary in dealing with the limitations of any one methodology.