WATER AND ION BALANCE IN RAT THYMOCYTES UNDER APOPTOSIS
INDUCED WITH DEXAMETHASONE OR ETOPOSIDE. OSMOTIC CELL VOLUME DECREASE
A. A. Vereninov,1 E. V. Volgareva, V. V. Matveev, A. V. Moshkov, Yu. M. Rosanov, A. V. Shirokova,
V. E. Yurinskaya
Institute of Cytology RAS, St. Petersburg;
1 e-mail: veren@mail.cytspb.rssi.ru
Cell ion and water balance was studied with respect to analysis of the osmotic model of apoptotic volume
decrease (AVD) in rat thymocytes under dexamethasone (1 μM, 4-6 h) or etoposide (50 μM, 5 h) treatment.
Intracellular water content was determined by measurement of cell buoyant density in continuous Percoll gradient,
while intracellular potassium and sodium contents were determined by flame emission analysis. Apoptosis was
verified by an increase in cell buoyant density, fluorescence of cells stained with Acridine orange and Ethidium
bromide (flow cytometry), by changes in the cell cycle and the appearance of sub-diploid peak in the DNA histogram
(flow cytometry), and by a decrease in cell size examined with light microscope. A separate fraction of dense cells
with reduced size was found to appear after dexamethasone or etoposide treatment. This fraction was considered as
apoptotic. An increase in buoyant density of apoptotic cells corresponded to a decrease in cell water content. In
apoptotic cells vs. cells with normal buoyant density, the intracellular potassium content was lower, but sodium
content was higher. The sum of potassium and sodium contents was lower in apoptotic cells. Taken into account the
loss of anions, associated with the loss of cations, the bulk decrease in ions content has been sufficient to be
accounted for cell volume decrease on the basis of the ion-osmotic model.
Key words: apoptosis, thymocytes, cell potassium, cell sodium, cell water, dexametasone, etoposide
Back
Contents
Main
|
