Valentina E Yurinskaya

Institute of Cytology St.-Petersburg, Russia

This brief review explores the role of intracellular K+ during the transition of cells from quiescence to proliferation and the induction of apoptosis. We focus on the relationship between intracellular K+ and the growth and proliferation rates of different cells, including transformed cells in culture as well as human quiescent T cells and mesench...

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 vali...

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 caus...

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...

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. He...

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, the cooperation of transporters and channels of the plasma membrane in holding the ionic homeostasis of the whole cell remains poorly characterized because...

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 unidi...

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...

Monovalent ions, sodium in particular, are involved in fundamental cell functions, such as water balance and electric processes, intra- and intercellular signaling, cell movement, pH regulation and metabolite transport into and out of cells. Fluorescent probes are indispensable tools for monitoring intracellular sodium levels in single living cells...

Assessing the expression of channels on the cell membrane is a necessary step in studying the functioning of ion channels in living cells. We explore, first, if endogenous VRAC can be assayed using flow cytometry and a commercially available antibody against an extracellular loop of the LRRC8A, also known as SWELL1, subunit of the VRAC channel. The...

Many evidence shows that K⁺ ions are required for cell proliferation, however, changes in intracellular K⁺ concentration during transition of cells from quiescence to cycling are insufficiently studied. Here, we show using flame emission assay that a long-term increase in cell K⁺ content per g cell protein is a mandatory factor for transition of qu...

Fluorescent probes are a popular and indispensable tool for monitoring sodium concentration in living cells in situ. Calibration of fluorescent probes inside cells commonly uses ionophores to equilibrate intracellular and external ion concentrations. Here we test this calibration method using in parallel classical flame emission assay. Suspension h...

Monovalent ions are involved in a vast array of cellular processes. Their movement across the cell membrane is regulated by numerous channels and transporters. Identification of the pathways responsible for redistribution of ions and cell water in living cells is hampered by their strong interdependence. This difficulty can be overcome by computati...

The response of fluorescent ion probes to ions is affected by intracellular environment. To properly calibrate them, intracellular concentration of the measured ion must be made equal to its extracellular concentration. In the first, computational, part of this work, we show, using the example of potassium, that the two requirements for ion equilib...

The study aims to know how the apoptotic alteration of cell ionic balance follows from the quantitatively characterised time dependent decrease in the sodium pump rate constant and changes in permeability coefficients of Cl-, K+, and Na+ channels. New experimental data on changes in cell K+, Na+, Cl-, water contents, and the Na+/K+-ATPase-mediated...

The development of ion‐sensitive fluorescent probes enables the measurement of intracellular concentrations of ions (such as H ⁺ , K ⁺ , Na ⁺ , Ca ²⁺ , etc.) in a non‐invasive manner. One major complication with their use arises from their unpredictable behavior inside the cell, which makes it necessary to calibrate them in situ . Calibration impli...

A decrease in flow cytometric forward light scatter (FSC) is commonly interpreted as a sign of apoptotic cell volume decrease (AVD). However, the intensity of light scattering depends not only on the cell size but also on its other characteristics, such as hydration, which may affect the scattering in the opposite way. That makes estimation of AVD...

Monovalent ion traffic across the cell membrane occurs via various pathways. Evaluation of individual fluxes in whole cell is hampered by their strong interdependence. This difficulty can be overcome by computational analysis of the whole cell flux balance. However, the previous computational studies disregarded ion movement of the self-exchange ty...

The results of this study of the ultrastructural changes in U-937 cells in the apoptotic state are largely consistent with analogous data available in the literature. However, we also obtained original data on the ultrastructural changes in cellular organelles and immunocytochemical localization and distribution of proteasomes. It was shown that, w...

Lithium transport across the cell membrane is interesting in the light of general cell physiology and because of its alteration during numerous human diseases. The mechanism of Li+ transfer has been studied mainly in erythrocytes with a slow kinetics of ion exchange and therefore under the unbalanced ion distribution. Proliferating cultured cells w...

Many vital processes in animal cells depend on monovalent ion transport across the plasma membrane via specific pathways. Their operation is described by a set of nonlinear and transcendental equations that cannot be solved analytically. Previous computations had been optimized for certain cell types and included parameters whose experimental deter...

Background/Aims: Osmotic cell shrinkage is a powerful trigger of suicidal cell death or apoptosis, which is paralleled and enforced by apoptotic volume decrease (AVD). Cells counteract cell shrinkage by volume regulatory increase (RVI). The present study explored the response of human U937 cells to hypertonic solution thus elucidating the relations...

Changes in intracellular water, K+ and Na+ of U937 cells incubated in hyperosmolar medium supplemented with 200 mM sucrose have been studied. Cells were stained with acrydine orange, ethydium bromide, APOPercentage dye, which marks the phosphatidyl serine distribution on the plasma membrane; and FLICA polycaspase fluorescent dye. It was found that...

Cells dying according to the apoptotic program, unlike cells dying via an unprogrammed mode, are able to avoid swelling and osmotic bursting with membrane disruption.There are indications that apoptosis is accompanied by suppression of the Na+/K+ pump and changes in the K+ and Cl− channels. It remains unclear how ion fluxes through individual ion p...

The K+, Na+, and Cl− balance and K+ (Rb+) and 36Cl− fluxes in U937 cells induced to apoptosis by 0.2 or 1 μM staurosporine were studied using flame emission and radioisotope techniques. It is found that two-thirds of the total decrease in the amount of intracellular osmolytes in apoptotic cells is accounted for by monovalent ions and one-third cons...

The balance of K+, Na+, and Cl− fluxes across the cell membrane with the Na+/K+ pump, ion channels, and Na+K+2Cl− (NKCC) and Na+-Cl− (NC) cotransport was calculated to determine the mechanism of cell shrinkage in apoptosis. It is shown that all unidirectional K+, Na+, and Cl− fluxes; the ion channel permeability; and the membrane potential can be f...

The balance of K+, Na+ and Cl- fluxes through cell membrane with the Na+/K+ pump, ion channels and NKCC and NC cotransporters is considered. It is shown that all unidirectional K+, Na+ and Cl- fluxes through cell membrane, permeability coefficients of ion channels and membrane potential can be computed for balanced ion distribution between cell and...

K+, Na+ and Cl- balance and K+ (Rb+) and 36Cl fluxes in during apoptosis of U937 cells caused by 0.2 or 1μM staurosporine were studied by flame emission and radiotracer techniques. It is found that monovalent ion redistribution accounts for 2/3 of all decrease in the amount of intracellular osmolytes in apoptotic cells while 1/3 is due to the loss...

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...

Unidirectional (22)Na, Li(+) and Rb(+) fluxes and net fluxes of Na(+) and K(+) were measured in U937 human leukemic cells before and after induction of apoptosis by staurosporine (1 microM, 4 h) to answer the question which ion transporter(s) are responsible for changes in cell ion and water balance at apoptosis. The original version of the mathema...

Staurosporine (STS) and etoposide (Eto) induced apoptosis of the human histiocytic lymphoma cells U937 were studied to determine the role of monovalent ions in apoptotic cell shrinkage. Cell shrinkage, defined as cell dehydration, was assayed by measurement of buoyant density of cells in continuous Percoll gradient. The K+ and Na+ content in cells...

The mechanism of apoptotic cell volume decrease was studied in rat thymocytes treated with dexamethasone (Dex) or etoposide (Eto). Cell shrinkage, i.e. dehydration, was quantified by using buoyant density of the thymocytes in a continuous Percoll gradient. The K+ and Na+ content of cells from different density fractions were assayed by flame emissi...

Aqueous and ionic balance in cells was studied using the cell floating density measurement in Percoll gradient for cellular water determination and flame-emission analysis for K+ and other cations determination. The experiments were carried out on the known apoptosis models - rat thymocytes, in which apoptosis was induced by dexamethasone (1 mcM, 4...

This work, using RT PCR, studied expression of mRNAs encoding ion transporters, the Na/H antiporter (NHE1), the beta subunit of the Na,K-ATPase pump (ATP1B1), the NaK2Cl symporter (NKCC1), and some proteins unrelated to ion transport: the serum and glucocorticoid dependent kinase (hSGK), beta-actin, a glycolytic enzyme (GAPDH), and regulators of pr...

Changes in the levels of mRNAs encoding ion transporters (ATP1B1, NHE1, NKCC1), β-actin, GAPDH, regulators of proliferation and apoptosis (p53, Bcl-2) and kinase hSGK, involved in cell water regulation, were studied using RT PCR in the peripheral human lymphocytes activated with phytohemagglutinin for 4-24 h. The common, «grouped», effect that was...

Potentiometric biosensors based on choline esterase, immobilized in fluoroplastic and cellulose acetate matrices directly at the surface of a pH-responsive film electrode, are examined. Characteristics of the sensors are compared in solutions of a substrate (acetylcholine iodide). The influence of some divalent cations on the catalytic activity of...

This chapter presents an overview of a potentiometric biosensor with an enzyme membrane prepared directly at the surface of ion-selective electrode. An electrode with a pH-selective PVC-membrane was used as a pH sensor. The electrode is of a “solid contact” type without internal reference solution. Tris-(n-octyloxyethyl)amine served as a H+-selecti...

The electrochemical properties of the membranes were studied in sodium acetate solutions as functions of qualitative and quantitative membrane composition. Compositions were revealed which will guarantee the widest range of functioning. The selectivity of the membranes for acetate ions was studied in the presence of a number of foreign anions as a...

The electrode properties of polyvinyl chloride membranes plasticized with dibutyl phthalate and containing different amounts of valinomycin (0, 0. 25, 0. 063, and 0. 125%) were investigated in picrate solutions with cations H** plus , K** plus , and Na** plus . It is found that the properties of valinomycin-containing membranes greatly depend on th...