title: Pump and channel K (Rb+) fluxes in apoptosis of human lymphoid cell line U937.
abstract: Ouabain-sensitive (OS) and -resistant (OR) Rb(+) influx was examined in three sublines of U937 cells to compare alterations of K(+) channel permeability and the Na(+),K(+)-ATPase pump leading to the shift in ion and water balance during apoptosis induced by 0.2 and 1microM staurosporine (STS) for 4-5 h. Cell K(+), Rb(+), Na(+) and Cl(-) content was determined by flame photometry and (36)Cl distribution. Changes in cell water content were monitored by measurement of buoyant cell density and distribution of [(3)H]-glycerol or 3-O-methyl-D-[(3)H]glucose. Apoptosis was detected by DNA flow cytometry and light microscopy of the native cells stained with acridine orange. Treatment with 0.2 microM STS for 5 hours led to mild apoptosis with 10-13 % cell dehydration and either moderate increase of channel mediated Rb(+) influx without significant changes in the pump activity or moderate decrease of pump Rb(+) influx without significant change of channel influx, depending on the cell line used. Treatment with 1 microM STS was followed by 18-23 % cell dehydration, a decrease of the pump activity and a small or insignificant increase in the OR Rb(+) influx in all studied sublines. It is concluded that moderate apoptotic cell shrinkage may be associated with both an increase in K(+) channel permeability and inhibition of the pump whereas more remarkable shrinkage occurs presumably due to inhibition of the pump.
authors.affiliation: Institute of Cytology RAS, St-Petersburg, Russia. veren@mail.cytspb.rssi.ru
authors.forename: Alexey A
authors.initials: AA
authors.lastname: Vereninov
authors.forename: Andrey A
authors.initials: AA
authors.lastname: Rubashkin
authors.forename: Tatyana S
authors.initials: TS
authors.lastname: Goryachaya
authors.forename: Alexey V
authors.initials: AV
authors.lastname: Moshkov
authors.forename: Yuriy M
authors.initials: YM
authors.lastname: Rozanov
authors.forename: Anna V
authors.initials: AV
authors.lastname: Shirokova
authors.forename: Ekaterina G
authors.initials: EG
authors.lastname: Strelkova
authors.forename: Florian
authors.initials: F
authors.lastname: Lang
authors.forename: Valentina E
authors.initials: VE
authors.lastname: Yurinskaya