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Rearrangement of ionic homeostasis caused by an increase in external osmolarity in the U937 cell model with different cotransporters and parameters like in cells balanced with the standard medium. Direct Iso-Hyper (A-D) and reverse Hyper-Iso (E-H) transitions.
Source publication
The work provides a modern mathematical description of animal cell electrochemical system under a balanced state and during the transition caused by an increase in external osmolarity, considering all the main ionic pathways in the cell membrane: the sodium pump, K+, Na+, Cl- electroconductive channels and cotransporters NC, KC, and NKCC. The descr...
Contexts in source publication
Context 1
... cases is at first glance similar and copies that of the direct Iso-Hyper transition. However, a more detailed analysis shows that there are certain differences between changes in the direct and reverse direction, and between the cases of sucrose and NaCl hyperosmolar solutions (Figure 2). ...
Context 2
... /2021 Figure 7. Cell water, K + , and Na + content in living K562 (A, D), Jurkat (B, E), and U937 (C, F) cells before and after 4 h incubation in hyperosmolar medium with 200 mM sucrose (510 mOsm). The broad gray lines show the level of the initial water and ion content in hyperosmolar medium (15 min incubation). ...
Citations
... Our thanks to Igor Raikov, a student of the Alferov Federal State Academic University RAS, Russia, for checking the use of the BEZ02BC file on a 32-bit computer. This manuscript has been released as a Pre-Print at BioRxiv, online Nov. 15, 2021 (Yurinskaya and Vereninov, 2021b). ...
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. It is found that, in contrast to countless statements in the literature that cell volume restoration requires the activation of certain ion channels and transporters, the cellular responses such as RVI and AVD can occur in an electrochemical system like U937 cells without any changes in the state of membrane channels or transporters. These responses depend on the types of chloride cotransporters in the membrane and differ in a hyperosmolar medium with additional sucrose and in a medium with additional NaCl. This finding is essential for the identification of the true changes in membrane channels and transporters responsible for RVI and AVD in living cells. It is determined which changes in membrane parameters predicted by computational analysis are consistent with experimental data obtained on living human lymphoid cells U937, Jurkat, and K562 and which are not. An essential part of the results is the developed software that allows researchers without programming experience to calculate the fluxes of monovalent ions via the main transmembrane pathways and electrochemical gradients that move ions across the membrane. The software is available for download. It is useful for studying the functional expression of the channels and transporters in living cells and understanding how the cell electrochemical system works.
