Isovolumetric regulation of c6 rat glioma cells in hyperosmotic
media.
Mountian, Irina, and Willy Van Driessche.
Laboratory of Physiology, K. U. Leuven, Campus Gasthuisberg, B
-3000, Leuven, Belgium
APStracts 3:0255C, 1996.
Volume regulation of C6 glioma cells was studied in response to a
gradual increase of extracellular osmolality from 300 to 440 mOsm/kg,
at 37 degrees C. Maintenance of cell size depended on the rate of
osmolality increase (CR) : at CR = 3 mOsm/(kg.min) cell volume was
kept constant, while it decreased progressively at CR of 6 or 9
mOsm/(kg.min). The ability of C6 cells to maintain their volume is
termed isovolumetric regulation (IVR). Reducing temperature to 22
degrees C inhibited IVR significantly. Also, bumetanide and ouabain
blocked the regulation, while 5-(N,N-dimethyl)-amiloride (DMA) did
not affect IVR. Extracellular acidification rate (EAR) was studied by
microphysiometry. EAR gradually decreased in presence and increased
in absence of IVR. Experiments with DMA show that these changes in
EAR were related to the activity of Na+/H+ exchanger. It was
stimulated by cell shrinkage, but not by hyperosmolality itself. Our
data demonstrate that C6 glioma cells are able to prevent volume
decrease at a low rate of elevation of external osmolality and at 37
degrees C. This process requires electrolyte uptake by Na+/K+/2Cl-
cotransporter and Na+/K+ pump.
Received 5 June 1996; accepted in final form 24 July 1996.
APS Manuscript Number C315-6.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 21 August 1996