Hyperosmolality inhibits sodium absorption and chloride secretion
in mimcd-k2 cells.
Green, Ryan B., Margaret J. Slattery, Elisa Gianferrari, Neil L.
Kizer, David E. McCoy, and Bruce A. Stanton.
Department of Physiology, Dartmouth Medical School, Hanover, New
Hampshire USA 03755
APStracts 3:0170F, 1996.
Previously we demonstrated that a cell line derived from mouse inner
medullary collecting duct (mIMCD-K2) absorbs Na+ and secretes Cl- by
electrogenic mechanisms and that AVP stimulates Cl- secretion
(12,13,19,30). The objective of the present study was to determine if
hyperosmolality, both acute (min) and chronic (wks), affects
electrogenic Na+ absorption (INasc) and electrogenic Cl- secretion
(IClsc) across the IMCD. To this end, we measured INasc and IClsc
across monolayers of mIMCD-K2 cells mounted in Ussing-type chambers.
Osmolality was increased from 290 to 590 mOsm/kg H2O by adding 200
mOsm/kg H2O of NaCl and 100 mOsm/kg H2O of urea or 300 mOsm/kg H2O of
sucrose to the bathing solutions. Acute and chronic hyperosmolality
reduced basal INasc and IClsc and the AVP-stimulated rise in IClsc.
These findings indicate that osmolality is an important determinant
of INasc and IClsc across IMCD cells and that the osmolality of the
interstitial fluid should be considered when evaluating the effects
of hormones and other factors on Na+ and Cl- transport by the IMCD.
Received 7 May 1996; accepted in final form 17 September 1996.
APS Manuscript Number F135-6.
Article publication pending Am. J. Physiol. (Renal Fluid Electrolyte
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 7 October 1996