title: Lumen-positive chloride transport potential in the early distal tubule of Triturus kidney: its absolute dependence on the presence of Na+ and K+ in the luminal fluid.
abstract: Microperfusion experiments with Na+-free and/or K+-free solutions revealed that the generation of Cl- -dependent lumen-positive transtubular potentials of the early distal tubule of Triturus kidney was absolutely dependent on the presence of both Na+ and K+ in the lumen. Increases in luminal Na+ or K+ concentration increased the luminal positivity in a saturable manner, and the half saturation concentration was found to be about 1 mM for both cations. The results strongly suggest that Cl- is cotransported with Na+ and K+ across the luminal membrane.
mesh_terms: D000818:Animals; D001464:Barium / Q000494:pharmacology; D002463:Cell Membrane Permeability / Q000187:drug effects; D002712:Chlorides / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D007473:Ion Channels / Q000187:drug effects / Q000378:metabolism*; D007684:Kidney Tubules / Q000378:metabolism*; D007686:Kidney Tubules, Distal / Q000378:metabolism*; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects; D011188:Potassium / Q000378:metabolism* / Q000494:pharmacology; D012964:Sodium / Q000378:metabolism* / Q000494:pharmacology; D014319:Triturus / Q000378:metabolism*
chemical_list: D002712:Chlorides; D007473:Ion Channels; D001464:Barium; D012964:Sodium; D011188:Potassium