We tested the hypothesis that astrocytes swell in response to ethanol (EtOH
) exposure. The experimental approach consisted of an electrical impedance
method designed to measure cell volume. In chronic experiments, EtOH (100 m
M) was added to the culture media for 1, 3, or 7 days. The cells were subse
quently exposed for 15 min to isotonic buffer (122 mM NaCl) also containing
100 mM EtOH. Subsequently, the cells were washed and exposed to hypotonic
buffer (112 mM NaCl) containing 100 mM mannitol. Chronic exposure to EtOH l
ed to a marked increase in cell volume compared with control cells. Specifi
c anion cotransport blockers, such as SITS, DIDS, furosemide, or bumetanide
, when simultaneously added with EtOH to hyponatremic buffer, failed to rev
erse the EtOH-induced effect on swelling. In acute experiments, confluent n
eonatal rat primary astrocyte cultures were exposed to isotonic media (122
mM NaCl) for 15 min, followed by 45-min exposure to hypotonic media (112 mM
NaCl, mimicking in vivo hyponatremic conditions associated with EtOH withd
rawal) in the presence of 0-100 mM EtOH. This exposure led to a concentrati
on-dependent increase in cell volume. Combined, these studies suggest that
astrocytes exposed to EtOH accumulate compensatory organic solutes to maint
ain cell volume, and that in response to hyponatremia and EtOH withdrawal t
heir volume increases to a greater extent than in cells exposed to hyponatr
emia alone. Furthermore, the changes associated with EtOH are osmotic in na
ture, and they are not reversed by anion cotransport blockers. (C) 2001 Els
evier Science B.V. All rights reserved.