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.

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.

Cation-Chloride Cotransporters, Na/K Pump, and Channels in Cell Water/Ionic Balance Regulation Under Hyperosmolar Conditions: and Experimental Studies of Opposite RVI and AVD Responses of U937 Cells to Hyperosmolar Media.

Studying the transport of monovalent ions across the cell membrane in living cells is complicated by the strong interdependence of fluxes through parallel pathways and requires therefore computational analysis of the entire electrochemical system of the cell. Current paper shows how to calculate changes in the cell water balance and ion fluxes caused by changes in the membrane channels and transporters during a normal regulatory increase in cell volume in response to osmotic cell shrinkage (RVI) followed by a decrease in cell volume associated with apoptosis (AVD). Our recently developed software is used as a computational analysis tool and the established human lymphoid cells U937 are taken as an example of proliferating animal cells.

Cation-Chloride Cotransporters, Na/K Pump, and Channels in Cell Water and Ion Regulation: and Experimental Studies of the U937 Cells Under Stopping the Pump and During Regulatory Volume Decrease.

Cation-coupled chloride cotransporters play a key role in generating the Cl electrochemical gradient on the cell membrane, which is important for regulation of many cellular processes. However, a quantitative analysis of the interplay between numerous membrane transporters and channels in maintaining cell ionic homeostasis is still undeveloped. Here, we demonstrate a recently developed approach on how to predict cell ionic homeostasis dynamics when stopping the sodium pump in human lymphoid cells U937.

Balance of Na, K, and Cl Unidirectional Fluxes in Normal and Apoptotic U937 Cells Computed With All Main Types of Cotransporters.

Fluxes of monovalent ions through the multiple pathways of the plasma membrane are highly interdependent, and their assessment by direct measurement is difficult or even impossible. Computation of the entire flux balance helps to identify partial flows and study the functional expression of individual transporters. Our previous computation of unidirectional fluxes in real cells ignored the ubiquitous cotransporters NKCC and KCC.

Fluorometric Na Evaluation in Single Cells Using Flow Cytometry: Comparison with Flame Emission Assay.

Background/aims: Sodium is a key player in the fundamental cell functions. Fluorescent probes are indispensable tools for monitoring intracellular sodium levels in single living cells. Since the fluorescence of sodium-sensitive dyes in cells is significantly different from that in an aqueous solution, the fluorescence signal is calibrated in situ indirectly using ionophores for equalizing external and intracellular ion concentration.