Unidirectional fluxes of monovalent ions in human erythrocytes compared with lymphoid U937 cells: Transient processes after stopping the sodium pump and in response to osmotic challenge

Abstract

Recently, we have developed software that allows, using a minimum of required experimental data, to find the characteristics of ion homeostasis and a list of all unidirectional fluxes of monovalent ions through the main pathways in the cell membrane both in a balanced state and during the transient processes. Our approach has been successfully validated in human proliferating lymphoid U937 cells during transient processes after stopping the Na/K pump by ouabain and for staurosporine-induced apoptosis. In present study, we used this approach to find the characteristics of ion homeostasis and the monovalent ion fluxes through the cell membrane of human erythrocytes in a resting state and during the transient processes after stopping the Na/K pump with ouabain and in response to osmotic challenge. Due to their physiological significance, erythrocytes remain the object of numerous studies, both experimental and computational methods. Calculations showed that, under physiological conditions, the K+ fluxes through electrodiffusion channels in the entire erythrocyte ion balance is small compared to the fluxes through the Na/K pump and cation–chloride cotransporters. The proposed computer program well predicts the dynamics of the erythrocyte ion balance disorders after stopping the Na/K pump with ouabain. In full accordance with predictions, transient processes in human erythrocytes are much slower than in proliferating cells such as lymphoid U937 cells. Comparison of real changes in the distribution of monovalent ions under osmotic challenge with the calculated ones indicates a change in the parameters of the ion transport pathways through the plasma membrane of erythrocytes in this case. The proposed approach may be useful in studying the mechanisms of various erythrocyte dysfunctions.

The Role of Intracellular Potassium in Cell Quiescence, Proliferation, and Death

“…At a cell culture density (0.5-1.0) × 10 6 cells/mL K + Na + Human blood lymphocytes [10,27] Quiescent G0 0.6 0.1-0.12 Competent G0/G1 0.6 0.12 Cycling G1/S 0.8-0.9 0.12-0.15 Human leukemia T cells Jurkat 0.8-0.9 0.15-0.2 [27] Human histiocytic lymphoma cells U937 0.8-1.1 0.27-0.30 [28] Human erythroleukemia cells K562 * 0.9-1.1 0.1-0.15 Rat thymocytes 0.95-0.98 0.17-0.25 [29] Human red blood cells, RBC ** 0.29-0.31 0.02-0.03 [30] * Our unpublished data on K562 cells. ** Data on red blood cells are given in relation to the content of cellular hemoglobin [30].…”