title: Vasopressin-enhanced urea transport by rat inner medullary collecting duct cells in culture.
abstract: The distal inner medullary collecting duct (IMCD) is critical in the urinary concentrating process, in part because it is the site of vasopressin (AVP)-regulated permeability to urea. The purpose of these experiments was to develop a cell culture model of the IMCD on permeable structure and to characterize the responsiveness to AVP. Rat IMCD cells were grown to confluence on collagen-coated Millipore filters glued onto plastic rings. To assess the time required to achieve confluence, the transepithelial resistance was measured periodically and was found to be stable after 2 weeks, at a maximal value of 595 +/- 22 omega cm2. In separate monolayers the effect of AVP on inulin and urea permeability was determined. While inulin permeability was unchanged after AVP, urea permeability increased from 6.0 +/- 0.4 to peak values of 16.0 +/- 3.8 (10 nM), 23.1 +/- 3.9 (1 microM) and 28.1 +/- 4.9 (10 microM) x 10(-6) cm s-1 (n = 24). In 10 other monolayers, after the addition of 1 mM 8-Br-cAMP, urea permeability increased from 5.1 +/- 0.3 to 8.1 +/- 1.6 x 10(-6) cm s-1 and, after 8-Br-cAMP + 3-isobutyl-1-methylxanthine, to 12.2 +/- 0.7 x 10(-6) cm s-1. We conclude that rat IMCD cells grown in culture exhibit the characteristics of a 'tight' epithelium. Inulin and urea permeability are not different in the absence of AVP, consistent with high resistance junctional complexes. Furthermore, IMCD cells retain the capacity for AVP-regulated urea permeability, a characteristic feature of this nephron segment in vivo.
authors: Thorndike Memorial Laboratory, Boston City Hospital, MA 02118.
authors: J H
authors: JH
authors: Schwartz
authors: H H
authors: HH
authors: Bengele
authors: E R
authors: ER
authors: McNamara
authors: E A
authors: EA
authors: Alexander
mesh_terms: D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport / Q000187:drug effects / Q000502:physiology; D002463:Cell Membrane Permeability / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D004553:Electric Conductivity / Q000187:drug effects; D007679:Kidney Medulla / Q000166:cytology* / Q000187:drug effects / Q000502:physiology; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D051381:Rats; D014508:Urea / Q000493:pharmacokinetics*; D014667:Vasopressins / Q000494:pharmacology*
chemical_list: D014667:Vasopressins; D015124:8-Bromo Cyclic Adenosine Monophosphate; D014508:Urea