CHANGES IN K+, Na+ AND Cl– CONTENTS AND K+ AND Cl– FLUXES DURING APOPTOSIS
OF U937 CELLS BY STAUROSPORINE. ON THE MECHANISM OF CELL DEHYDRATION IN APOPTOSIS
V. E. Yurinskaya, T. S. Goryachaya, A. A. Rubashkin, A. V. Shirokova, A. A. Vereninov 1
Institute of Cytology RAS, St. Petersburg;
1 e-mail: verenino@mail.ru
K+, Na+ and Cl– balance and K+ (Rb+) and
36Cl fluxes in during apoptosis of U937 cells caused by 0.2 or
1 μM staurosporine were studied by flame emission and radiotracer techniques. It is found that monovalent ion
redistribution accounts for 2/3 of all decrease in the amount of intracellular osmolytes in apoptotic cells while
1/3 is due to the loss of other intracellular osmolytes. Na+ gain in apoptotic cells hampers dehydration is caused
by K+ and Cl– loss. It is found that the rate of equilibration of 36Cl, Rb+ (K+)
and 22Na+ between cells and the medium
exceeds significantly the rate of alteration of cell ion content associated with apoptosis. It is concluded that
apoptotic changes should be considered as a drift of the balanced ion distribution. Alteration of the ion balance
in apoptosis, caused by 0.2 iM staurosporine, is associated with an increase in the uabain-resistant Rb+(K+)
«channel» influx and insignificant alteration of the uabain-sensitive «pump» influx. Stronger apoptosis, induced
by 1 μM staurosporine, is associated with a decrease in the pump fluxes and insignificant changes in the «channel»
Rb+ (K+) fluxes. Decreasing of the Cl– level in apoptotic cells by a factor 1.4—1.8 is accompanied with a
decrease in the flux, by a factor 1.2—1.6.
Key words: cell ion balance, apoptosis, ion transporters, monovalent ion fluxes, cell Cl–
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