title: Sodium cotransport systems in epithelial secretion.
abstract: 1. After considering the direct coupling and indirect coupling to the sodium gradient in sodium-dependent secretion across epithelia, the properties of the Na-K-Cl cotransporter involved in active chloride secretion and active chloride absorption are summarized. 2. A comparison between cellular mechanism of secretion and absorption shows that the direction of transepithelial transport is determined mainly by the intracellular localization of sodium cotransport systems and sodium-independent leaks. 3. Sodium cotransport systems, performing a similar function in various epithelia or species, may provide a powerful model to study their function at a molecular level.
mesh_terms: D000818:Animals; D001692:Biological Transport; D001717:Birds; D004848:Epithelium; D012754:Sharks; D015222:Sodium Channels / Q000378:metabolism*
chemical_list: D015222:Sodium Channels