Electrolyte transport mechanisms involved in regulatory volume
increase in c6 glioma cells.
Mountian, Irina, Kuang-Yi Chou, and Willy Van Driessche.
Laboratory of Physiology, K.U.Leuven, Gasthuisberg, B-3000, Leuven,
Belgium
APStracts 3:0163C, 1996.
Volume regulation of C6 glioma cells was studied with an automatic
system for monitoring cell thickness, while increasing bath
osmolality from 300 to 440 mOsm/kg. At 37 degrees C, tissues
incubated in solutions containing active substances (inositol, d
-Biotin, hydrocortisone, prostaglandin E1, insulin, transferin, sodium
selenite and triiodthyronine), responded to hyperosmotic challenge
with a typical regulatory volume increase (RVI). Lowering temperature
or removing the active substances inhibited osmoregulation.
Bumetanide, amiloride, 4,4'-diisothiocyanato-stilbene-2,2'disulfonic
acid or ouabain significantly reduced RVI. Ion substitutions of Na+,
Cl-, NaCl or HCO3- also importantly affected the process.
Extracellular acidification rate (EAR) was studied by
microphysiometry. Hyperosmotic shock induced an increase in EAR with
a time course that matched volume recovery. This increase in EAR was
prevented by amiloride. The data show that under hyperosmotic
conditions C6 cells are able to regulate their volume. Ion
substitutions and application of blockers demonstrate that Na+/H+ and
Cl-/HCO3- exchangers, and Na+/K+/2Cl- cotransporter are involved in
RVI. The rise in EAR is due to the enhanced activity of Na+/H+
antiporter, which seems to be volume, but not osmotic-dependent.
Received 10 October 1995; accepted in final form 25 April 1996.
APS Manuscript Number C610-5.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 28 May 96