title: Vasopressin and cAMP stimulate electrogenic chloride secretion in an IMCD cell line.
abstract: Previously, we demonstrated that the mIMCD-K2 cell line, derived from the inner medullary collecting duct (IMCD) of a transgenic mouse, secretes Cl- by an electrogenic mechanism [N. L. Kizer, B. Lewis, and B. A. Stanton, Am. J. Physiol. 268 (Renal Fluid Electrolyte Physiol. 37): F347-F355, 1995]. The objective of the present study was to characterize the cellular mechanisms of electrogenic Cl- secretion (IscCl) and to determine whether arginine vasopressin (AVP) and adenosine 3',5'-cyclic monophosphate (cAMP) stimulate IscCl. To this end, we measured IscCl across monolayers of mIMCD-K2 cells mounted in Ussing-type chambers. AVP increased IscCl with a Michaelis constant (Km) of 2.1 +/- 0.7 x 10(-12) M. 1-Desamino-8-D-AVP, a specific V2 receptor agonist, increased IscCl from 3.3 +/- 0.4 to 17.4 +/- 1.3 microA/cm2, 8-(4-Chlorophenylthio)-cAMP, a cell-permanent analogue of cAMP, a second messenger of AVP, increased IscCl from 1.4 +/- 0.3 to 15.2 +/- 1.2 microA/cm2. Furosemide and bumetanide, inhibitors of Na(+)-2Cl(-)-K+ cotransport, and 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS), an inhibitor of Cl-/HCO3- exchange, reduced IscCl when added to the basolateral solution. Our data suggest that AVP, via V2 receptors, and the second messenger cAMP stimulate IscCl and that Cl- secretion by mIMCD-K2 cells involves uptake of Cl- across the basolateral membrane by Na(+)-2Cl(-)-K+ cotransport and Cl-/HCO3- exchange and diffusion out of the cells across the apical membrane by cystic fibrosis transmembrane conductance regulator Cl- channels.
authors.affiliation: Department of Physiology, Dartmouth Medical School, Hanover, New Hampshire 03755, USA.
authors.forename: N L
authors.initials: NL
authors.lastname: Kizer
authors.forename: D
authors.initials: D
authors.lastname: Vandorpe
authors.forename: B
authors.initials: B
authors.lastname: Lewis
authors.forename: B
authors.initials: B
authors.lastname: Bunting
authors.forename: J
authors.initials: J
authors.lastname: Russell
authors.forename: B A
authors.initials: BA
authors.lastname: Stanton
mesh_terms: D000042:Absorption; D000818:Animals; D001127:Arginine Vasopressin / Q000494:pharmacology*; D002460:Cell Line; D018118:Chloride Channels / Q000037:antagonists & inhibitors; D002712:Chlorides / Q000378:metabolism*; D000242:Cyclic AMP / Q000031:analogs & derivatives / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004594:Electrophysiology; D007679:Kidney Medulla; D007685:Kidney Tubules, Collecting / Q000378:metabolism* / Q000502:physiology; D051379:Mice; D010121:Oxytocin / Q000494:pharmacology; D017483:Receptors, Vasopressin / Q000502:physiology; D012964:Sodium / Q000493:pharmacokinetics; D013873:Thionucleotides / Q000494:pharmacology
chemical_list: D018118:Chloride Channels; D002712:Chlorides; D017483:Receptors, Vasopressin; D013873:Thionucleotides; D001127:Arginine Vasopressin; C015929:8-((4-chlorophenyl)thio)cyclic-3',5'-AMP; D010121:Oxytocin; D012964:Sodium; D000242:Cyclic AMP