Ouabain switches Na+ transport to Na+/Na+ equivalent exchange in normal and apoptotic lymphoid cells |
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Authors: | A. A. Rubashkin |
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Affiliation: | 1. Institute of Cytology, Russian Academy of Sciences, St. Petersburg, 194064, Russia
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Abstract: | A theory of change of the ionic fluxes in the lymphoid cells in their transition from normal to apoptosis we have developed previously is applied to the analysis of Na+/Na+ exchange fluxes in human lymphoid cells U937 exposed to ouabain. We solve a system of equations describing changes in the intracellular concentrations of Na+, K+ and Cl?, membrane potential and cell volume. It is shown that the Na+ influx (I Na/Na) and output flux through the Na+/Na+ tract increased 4 times in 8 h after disconnecting Na+/K+-ATPase for normal cell U937. These fluxes increased 2.6 times for apoptotic cells. The value of I Na/Na after 8 h off pump by ouabain is 97% of the total Na+ input for both cell types. It is concluded that ouabain not only inhibits the Na+/K+-ATPase, but also increases Na+ exchange fluxes through the Na+/Na+ tract, thereby switching sodium transport across the membrane of lymphoid cells to Na+/Na+ equivalent exchange. |
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