title: Vasopressin-dependent coupling between sodium transport and water flow in a mouse cortical collecting duct cell line.
abstract: Water balance is achieved through the ability of the kidney to control water reabsorption in the connecting tubule and the collecting duct. In a mouse cortical collecting duct cell line (mCCD(c11)), physiological concentrations of arginine vasopressin increased both electrogenic, amiloride-sensitive, epithelial sodium channel (ENaC)-mediated sodium transport measured by the short-circuit current (Isc) method and water flow (Jv apical to basal) measured by gravimetry with similar activation coefficient K(1/2) (6 and 12 pM, respectively). Jv increased linearly according to the osmotic gradient across the monolayer. A small but highly significant Jv was also measured under isoosmotic conditions. To test the coupling between sodium reabsorption and water flow, mCCD(c11) cells were treated for 24 h under isoosmotic condition with either diluent, amiloride, vasopressin or vasopressin and amiloride. Isc, Jv, and net chemical sodium fluxes were measured across the same monolayers. Around 30% of baseline and 50% of vasopressin-induced water flow is coupled to an amiloride-sensitive, ENaC-mediated, electrogenic sodium transport, whereas the remaining flow is coupled to an amiloride-insensitive, nonelectrogenic sodium transport mediated by an unknown electroneutral transporter. The mCCD(c11) cell line is a first example of a mammalian tight epithelium allowing quantitative study of the coupling between sodium and water transport. Our data are consistent with the 'near isoosmotic' fluid transport model.
authors.affiliation: Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland.
authors.forename: Hans-Peter
authors.initials: HP
authors.lastname: Gaeggeler
authors.forename: Yann
authors.initials: Y
authors.lastname: Guillod
authors.forename: Dominique
authors.initials: D
authors.lastname: Loffing-Cueni
authors.forename: Johannes
authors.initials: J
authors.lastname: Loffing
authors.forename: Bernard C
authors.initials: BC
authors.lastname: Rossier
mesh_terms: D000818:Animals; D020346:Aquaporins / Q000378:metabolism; D001127:Arginine Vasopressin / Q000378:metabolism* / Q000494:pharmacology; D002460:Cell Line; D055724:Electrophysiological Phenomena; D053503:Epithelial Sodium Channels / Q000378:metabolism; D017136:Ion Transport / Q000187:drug effects; D007672:Kidney Cortex / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D007685:Kidney Tubules, Collecting / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D009995:Osmosis; D012964:Sodium / Q000378:metabolism*; D014867:Water / Q000378:metabolism*
chemical_list: D020346:Aquaporins; D053503:Epithelial Sodium Channels; D014867:Water; D001127:Arginine Vasopressin; D012964:Sodium