Metabolic and ionic responses of trout hepatocytes to anisosmotic exposure
Gerhard Krumschnabel1,*,
Ronald Gstir1,
Claudia Manzl1,
Caroline Prem1,
Diego Pafundo2 and
Pablo J. Schwarzbaum2
1 Institut für Zoologie und Limnologie, Abteilung für
Ökophysiologie, Universität Innsbruck, Technikerstraße 25,
A-6020 Innsbruck, Austria
2 Instituto de Química y Fisicoquímica Biológicas
(Facultad de Farmacia y Bioquímica), Universidad de Buenos
Aires, C1113AAD Buenos Aires, Argentina
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Fig. 1. Changes of relative cell water volume (Vr) of trout
hepatocytes exposed to (A) hyposmotic medium or (B) hyperosmotic medium,
followed by re-exposure to isosmotic conditions. C, A and B denote isosmotic
control saline, hyposmotic calibration saline (264 mosmol
l–1) and hyperosmotic calibration saline (308 mosmol
l–1), respectively. HYPO EXP (166 mosmol
l–1) and HYPER EXP (465 mosmol l–1) indicate
duration of experimental hypo- and hyperosmotic exposure. Values are means
± S.E.M. of 60 cells from four independent preparations.
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Fig. 2. Rates of oxygen consumption of trout hepatocytes after 30 min of incubation
under isosmotic (control; 284 mosmol l–1), hyposmotic (hypo;
166 mosmol l–1) and hyperosmotic (hyper; 465 mosmol
l–1) conditions. Data are expressed as % of the mean of the
control and are presented as means + S.E.M. of 12 (hyposmotic exposure) and 11
(hyperosmotic exposure) paired experiments. *P<0.05 compared with
controls.
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Fig. 3. Rates of lactate accumulation of cells incubated under iso- (284 mosmol
l–1), hypo- (166 mosmol l–1) or hyperosmotic
conditions (465 mosmol l–1). Rates were calculated from the
difference in lactate concentration at the onset and the end of each period,
divided by the duration of the period. Data are means + S.E.M. of 11
experiments.
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Fig. 4. Rates of glucose production of cells incubated under iso-, hypo- or
hyperosmotic conditions. Medium osmolarities and calculation of rates were as
in Fig. 3. Data are means +
S.E.M. of 15 (controls), 9 (hyposmotic) and 10 (hyperosmotic) experiments.
*P<0.05 compared with controls.
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Fig. 5. Alterations of intracellular free calcium ([Ca2+]i)
of individual hepatocytes induced by hyposmotic (A–C) or hyperosmotic
(D–F) conditions. Anisosmotic conditions were established at time zero
and were maintained throughout the experiment.
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Fig. 6. Intracellular free calcium ([Ca2+]i) of hepatocytes
under hyposmotic and hyperosmotic conditions established at time zero. Data
are means ± S.E.M. of 61 (hyposmotic) and 49 (hyperosmotic) cells.
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Fig. 7. Changes of intracellular pH of hepatocytes in response to hyposmotic and
hyperosmotic conditions and after re-establishing isosmotic conditions. The
duration of anisosmotic exposure is indicated by the black bar. Data are means
± S.E.M. of 54 (hyposmotic) and 18 (hyperosmotic) cells.
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Fig. 8. Changes of intracellular pH of individual hepatocytes induced by hyposmotic
(A–C) or hyperosmotic (D–F) conditions in complete and in
ion-substituted media. The presence of ion-substituted and anisosmotic media
is indicated by grey and black bars, respectively.
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© The Company of Biologists Ltd 2003
