Na+ i/K+ i imbalance contributes to gene expression in endothelial cells exposed to elevated NaCl.

High-salt consumption contributes to the development of hypertension and is considered an independent risk factor for vascular remodelling, cardiac hypertrophy and stroke incidence. Alterations in NO production, inflammation and endothelial cell stiffening are considered now as plausible mediators of cardiovascular dysfunction. We studied early responses of endothelial cells (HUVEC) caused by a moderate increase in extracellular sodium concentration. Exposure of HUVEC to elevated sodium within the physiological range up to 24 h is accompanied by changes in monovalent cations fluxes and Na,K-ATPase activation, and, in turn, results in a significant decrease in the content of PTGS2, IL6 and IL1LR1 mRNAs. The expression of NOS3 and FOS genes, as well as the abundance of cytosolic and nuclear NFAT5 protein, remained unchanged. We assessed the mechanical properties of endothelial cells by estimating Young's modulus and equivalent elastic constant using atomic force and interference microscopy, respectively. These parameters were unaffected by elevated-salt exposure for 24 h. The data obtained suggest that even small and short-term elevations of extracellular sodium concentration affect the expression of genes involved in the control of endothelial function through the Na+ i/K+ i-dependent mechanism(s).

Ouabain and Marinobufagenin: Physiological Effects on Human Epithelial and Endothelial Cells.

Long-term study on the identification of Na,K-ATPase endogenous inhibitors in mammalian tissues has resulted in the discovery of ouabain, marinobufagenin (MBG), and other cardiotonic steroids (CTS) in the blood plasma. Production of ouabain and MBG is increased in essential hypertension and other diseases associated with hypervolemia. Here, we compared the effects of ouabain and MBG on the Na,K-ATPase activity (measured as the transport of Na+, K+, and Rb+ ions) and proliferation and death of human renal epithelial cells (HRECs) and human umbilical vein endothelial cells (HUVEC) expressing α1-Na,K-ATPase. Ouabain concentration that provided the half-maximal inhibition of the Rb+ influx (IC50) into HRECs and HUVECs was 0.07 µM. In both types of cells, the IC50 values for MBG were 10 times higher than for ouabain. Incubation of HREC and HUVEC with 0.001-0.01 µM ouabain for 30 h resulted in 40% increase in the [3H]thymidine incorporation into DNA; further elevation of ouabain concentration to 0.1 µM completely suppressed DNA synthesis. MBG at the concentration of 0.1 µM activated DNA synthesis by 25% in HRECs, but not in HUVECs; 1 µM MBG completely inhibited DNA synthesis in HRECs and by 50% in HUVECs. In contrast to HRECs, incubation of HUVECs in the serum-free medium induced apoptosis, which was almost completely suppressed by ouabain and MBG at the concentrations of 0.1 and 3 µM, respectively. Based on these data, we can conclude that (i) the effect of MBG at the concentrations detected in the blood plasma (<0.01 µM) on HRECs and HUVECs was not due to the changes in the [Na+]i/[K+]i ratio; (ii) the effect of physiological concentrations of ouabain on these cells might be mediated by the activation of Na,K-ATPase, leading to cell proliferation.

Search for Intracellular Sensors Involved in the Functioning of Monovalent Cations as Secondary Messengers.

Maintenance of non-equilibrium Na+ and K+ distribution between cytoplasm and extracellular medium suggests existence of sensors responding with conformational transitions to the changes of these monovalent cations' intracellular concentration. Molecular nature of monovalent cation sensors has been established in Na,K-ATPase, G-protein-coupled receptors, and heat shock proteins structural studies. Recently, it was found that changes in Na+ and K+ intracellular concentration are the key factors in the transcription and translation control, respectively. In this review, we summarize results of these studies and discuss physiological and pathophysiological significance of Na+i,K+i-dependent gene expression regulation mechanism.

Level of Interleukins IL-6 and IL-15 in Blood Plasma of Mice after Forced Swimming Test.

We measured the concentrations of IL-6 and IL-15 in blood plasma of mice at different terms after forced swimming, taking into account exercise intensity and preliminary training. It was shown that training was an important factor affecting blood plasma level of IL both at rest and after single forced swimming: in trained animals, the concentration of both myokines increased immediately after swimming, while in untrained animals, this increase was observed only after 5 h. Changes in cytokine production against the background of training can be associated with various factors, including neuroendocrine mechanisms, stress, modification of intracellular signaling, as well as reorganization of transcriptional mechanisms in muscle fibers. The most important factor is shift in the ratio of monovalent cations (sodium and potassium) in the cytoplasm.

Regulation of Contractile Responses of Vascular Smooth Muscle Cells under Conditions of Hypoxia-Reoxygenation.

We analyzed the effects of hypoxia and reoxygenation on changes in contractile activity in rat aortic smooth muscles. Both hypoxia and reoxygenation induced relaxation of smooth muscle cells precontracted with high-potassium Krebs solution (30 mM KCl) or α1-adrenoceptor agonist phenylephrine. Vasodilation resulted from enhancement of potassium permeability of smooth muscle cell membranes caused by activation of voltage-gated potassium channels (triggered by both precontracting agents) or by opening of ATP-sensitive potassium channels (phenylephrine). In isolated smooth muscle cells, both hypoxia and inhibition of Na+,K+-ATPase with ouabain led to depletion of intracellular store of macroergic substances, reduced potassium concentration, and elevated the content of sodium ions.

Effects of Ouabain on Proliferation of Human Endothelial Cells Correlate with Na+,K+-ATPase Activity and Intracellular Ratio of Na+ and K.

Side-by-side with inhibition of the Na+,K+-ATPase ouabain and other cardiotonic steroids (CTS) can affect cell functions by mechanisms other than regulation of the intracellular Na+ and K+ ratio ([Na+]i/[K+]i). Thus, we compared the dose- and time-dependences of the effect of ouabain on intracellular [Na+]i/[K+]i ratio, Na+,K+-ATPase activity, and proliferation of human umbilical vein endothelial cells (HUVEC). Treatment of the cells with 1-3 nM ouabain for 24-72 h decreased the [Na+]i/[K+]i ratio and increased cell proliferation by 20-50%. We discovered that the same ouabain concentrations increased Na+,K+-ATPase activity by 25-30%, as measured by the rate of (86)Rb(+) influx. Higher ouabain concentrations inhibited Na+,K+-ATPase, increased [Na+]i/[K+]i ratio, suppressed cell growth, and caused cell death. When cells were treated with low ouabain concentrations for 48 or 72 h, a negative correlation between [Na+]i/[K+]i ratio and cell growth activation was observed. In cells treated with high ouabain concentrations for 24 h, the [Na+]i/[K+]i ratio correlated positively with proliferation inhibition. These data demonstrate that inhibition of HUVEC proliferation at high CTS concentrations correlates with dissipation of the Na+ and K+ concentration gradients, whereas cell growth stimulation by low CTS doses results from activation of Na+,K+-ATPase and decrease in the [Na+]i/[K+]i ratio.

Identification of Proteins Whose Interaction with Na+,K+-ATPase Is Triggered by Ouabain.

Prolonged exposure of different epithelial cells (canine renal epithelial cells (MDCK), vascular endothelial cells from porcine aorta (PAEC), human umbilical vein endothelial cells (HUVEC), cervical adenocarcinoma (HeLa), as well as epithelial cells from colon carcinoma (Caco-2)) with ouabain or with other cardiotonic steroids was shown earlier to result in the death of these cells. Intermediates in the cell death signal cascade remain unknown. In the present study, we used proteomics methods for identification of proteins whose interaction with Na+,K+-ATPase is triggered by ouabain. After exposure of Caco-2 human colorectal adenocarcinoma cells with 3 µM of ouabain for 3 h, the protein interacting in complex with Na+,K+-ATPase was coimmunoprecipitated using antibodies against the enzyme α1-subunit. Proteins of coimmunoprecipitates were separated by 2D electrophoresis in polyacrylamide gel. A number of proteins in the coimmunoprecipitates with molecular masses of 71-74, 46, 40-43, 38, and 33-35 kDa was revealed whose binding to Na+,K+-ATPase was activated by ouabain. Analyses conducted by mass spectroscopy allowed us to identify some of them, including seven signal proteins from superfamilies of glucocorticoid receptors, serine/threonine protein kinases, and protein phosphatases 2C, Src-, and Rho-GTPases. The possible participation of these proteins in activation of cell signaling terminated by cell death is discussed.

[Secretory Function of Skeletal Muscles: Producing Mechanisms and Myokines Physiological Effects].

Skeletal muscle cells secrete a variety of hormones and cytokines, which are referred to as myokines. Different modes of exercise are the main factor of myokines producing. The myokines expression level is increased in an exponential fashon proportional to the length of exercise and the amount of muscle mass engaged in the exercise. These myokines are described to communicate with cells in an autocrine/ paracrine manner. Thus it ensures the maintenance of homeostasis and adaptarion to physical stress. This myokines role is provided by a vriety of effects. It is assumed that exercise increases myokines transcription via signaling systems that are activated in response to a decrease in the partial pressure of oxygen, increasing the concentration of [Ca²âº] i and AMP. Significant prospects have the myokines investigation of the role in the different disorders correction. So now accumulated enough data for myokines consideration as a single functional system, which plays an important role in the adaptation mechanisms to the habitual exrcise.

Control of Myofibroblast Differentiation and Function by Cytoskeletal Signaling.

The cytoskeleton consists of three distinct types of protein polymer structures - microfilaments, intermediate filaments, and microtubules; each serves distinct roles in controlling cell shape, division, contraction, migration, and other processes. In addition to mechanical functions, the cytoskeleton accepts signals from outside the cell and triggers additional signals to extracellular matrix, thus playing a key role in signal transduction from extracellular stimuli through dynamic recruitment of diverse intermediates of the intracellular signaling machinery. This review summarizes current knowledge about the role of cytoskeleton in the signaling mechanism of fibroblast-to-myofibroblast differentiation - a process characterized by accumulation of contractile proteins and secretion of extracellular matrix proteins, and being critical for normal wound healing in response to tissue injury as well as for aberrant tissue remodeling in fibrotic disorders. Specifically, we discuss control of serum response factor and Hippo signaling pathways by actin and microtubule dynamics as well as regulation of collagen synthesis by intermediate filaments.

[THE ROLE OF HYDROGEN SULFIDE IN VOLUME-DEPENDENT MECHANISMS OF REGULATION OF VASCULAR SMOOTH MUSCLE CELLS CONTRACTILE ACTIVITY].

The hydrogen sulfide (H2S) influence on the contractile activity of vascular smooth muscle cells (SMC) was studied on endothelium-denuded aortic ring segments of male Wistar rats with method of mechanography. Contractions of SMS were induced by incubation in high potassium solution as well as in hyper-, hypo- and isosmotic solutions. 5-100 LM of H2S donor--sodium hydrosulfide (NaHS) increased mechanical tension of SMC precontracted with high potassium solution that was abolished by bumetanide--the inhibitor of Na+, K+, 2Cl(-) -cotransporter (NKCC), but 100-1000 microM of NaHS relaxed SMS. NaHS (10 microM) increased the amplitude of hyper- and isosmotic contraction, but not of hyposmotic contraction. NaHS (ImM) decreased the amplitude of hyper-, iso-, and hyposmotic contractions. The direct measurements of NKCC activity with radionuclide method showed an increase in NKCC activity under the action of 5-100 microM of NaHS. These findings suggest that low concentrations of H2S participate in the NKCC activation. This mechanism underlines constrictive action of H2S on smooth muscle cells.

[Gas Signalling in Mammalian Cells].

At the end of the last century after the discovery of signaling functions of nitric oxide (NO, II), a new class of biologically active substances was admitted. It includes so-called gas transmitters acting as intercellular and intracellular regulators of different physiological functions. Currently, this class includes such gases as NO, carbon monoxide (CO) and hydrogen sulfide (H2S). It was found that these gases regulate not only functions of the. gastrointestinal tract and the cardiovascular system, where it has been determined initially, but also affect the function of the central and peripheral nervous.systems. Apparently, they constitute a single complex of gas transmitters, which easily penetrates through the membrane and regulates numerous enzymatic and non enzymatic cells reactions. This review presents the mechanisms of gas transmitters' influence on the electrical and contractile properties of smooth muscle cells (SMC) as a possible new ways to interact with the "classical" intracellular signaling cascades (Ca2+, cyclic nucleotides) and effectors systems. On account of their interactions the role of cyclic nucleotides and calcium ions in the implementation of the signal gas molecules functions is analyzed. We summarize the literature data and the results of our own research on the role of SMC membrane ion-transporting systems in myogenic effects of NO, CO and H2S and describe possible reasons of gas transmitters multidirectional influence on the excitation-contraction coupling in SMC.

Cation-chloride cotransporters: regulation, physiological significance, and role in pathogenesis of arterial hypertension.

This review summarizes the data on the functioning of carriers providing electroneutral symport of sodium, potassium, and chloride (Na(+),K(+),2Cl(-) cotransport), potassium and chloride (K(+),Cl(-) cotransport), and sodium and chloride (K(+),Cl(-) cotransport) as well as molecular mechanisms of the regulation of these carriers and their physiological significance. We emphasized the involvement of chloride-coupled carriers in the regulation of cell volume and intracellular chloride concentration and novel data on the role of ubiquitous isoform of Na(+),K(+),2Cl(-) cotransporter NKCC1 in regulation of vascular smooth muscle contraction and activity of GABA(A) receptors. Finally, we analyzed the data on activation of NKCC1 in patients with essential hypertension and its role in the long-term maintenance of elevated systemic blood pressure and myogenic response in microcirculatory beds.

[3-Dimensional microscopy as a method for volume measurement in cells undergoing apoptosis].

Different patterns of cell volume perturbations are commonly used for modes of cell death: necrosis (cell swelling) and apoptosis (cell shrinkage). In this study we employed recently developed three dimensional microscopy for the measurement of the volume of attached vascular smooth muscle cells transfected with E1A-adenoviral protein. These cells undergo rapid apoptosis in the absence of growth factors or in the presence of staurosporine. In 30-60 min of serum deprivation the volume of these cells is increased by -40% that corresponds to the time point of maximal activation of caspase 3 and chromatin cleavage. In 10-15 min swollen cells exhibit morphological collapse indicated by formation of apoptotic bodies. In contrast to serum-deprived cells, staurosporine leads to attenuation of cell volume by 30%. In this case, apoptotic bodies are detected in -2.5 hr after maximal shrinkage. Thus, our results show that cell shrinkage can not be considered as universal hallmark of apoptosis. The role of stimulus-specific cell volume perturbation in the triggering of the cell death machinery should be examined further.

[Ionic mechanisms of carbon monoxide action on the contractile properties of smooth muscles of the blood vessels].

Carbon monoxide (CO) is one of a family of gas transmitters. In this article we present the results of mechanographic investigations of the mechanisms of CO action on a rat thoracic aorta segments. We found that relaxing effect of CO donor CORM-2 on vascular smooth muscles is mediated mainly by opening of voltage-dependent potassium channels in smooth muscle cells: 4-aminopyridine, blocking these channels, almost completely eliminated the CO-induced vasorelaxation of the segments precontracted by depolarization of the smooth muscle cells membranes with high potassium (30 mM KCl) solution or by phenylephrine (10 microM). For the first time we documented that CORM-2 reduces the nicardipine-sensitive input of 45Ca2+ in freshly isolated aorta cells. There are reasons to suggest that the L-type voltage-dependent calcium channels of vascular smooth muscle cells are another target for CO, which is implemented in the relaxing effect of this gas transmitter. Additional research is needed to determine the influence of ruthenium complexes (Ru(II)) on phenomenology of carbon monoxide effects.

Thermal inactivation of volume-sensitive K⁺,Cl⁻ cotransport and plasma membrane relief changes in human erythrocytes.

Previously, we reported that in mammalian erythrocytes irreversible annealing of spectrin heterodimers at 49-50 °C abolished cell volume-dependent regulation of ion carriers, thus suggesting an implication of a two-dimensional (2D) membrane carcass in volume sensing and/or signal transduction. To further examine this hypothesis, we employed atomic force microscopy. This method revealed folded membrane relief of fixed human erythrocytes with an average wave height of 3-5 nm covered by globular structures with a diameter of 40-50 nm and an average height of 1-2 nm. Erythrocyte swelling caused by reduction of medium osmolality decreased the height of membrane surface waves by 40 % and increased K(+),Cl(-) cotransport by approximately sixfold. Both volume-sensitive changes of membrane relief and activity of K(+),Cl(-) cotransporter were abolished by a 10-min preincubation at 50 °C. Our results strongly suggest that volume-dependent alterations of the human erythrocyte membrane relief are caused by reorganization of the 2D spectrin-actin network contributing to regulation of the activity of volume-sensitive ion transporters.

Laser interference microscopy of amphibian erythrocytes: impact of cell volume and refractive index.

This study examined the action of anisosmotic media on the volume of nucleated erythrocytes isolated from Rana temporaria. Elevation of medium osmolarity from 100 to 345 mOsm resulted in attenuation of mean cell volume by more than 3-fold, estimated by hematocrit measurement. By contrast to this 'classic' erythrocyte volume evaluation technique, we did not observe any significant cell volume modulation by examining the 3D reconstruction of erythrocyte interference images obtained by laser interference microscopy. Comparative analysis of mean cell volume, phase height and cell area appraised by laser interference microscopy showed that the lack of visible alterations of phase image geometry was caused by sharp elevation of the average refractive index of the cytoplasm in shrunken cells. Thus, our results show for the first time that laser interference microscopy in combination with a direct method for cell volume measurement may be employed for estimation of the refractory index of intracellular milieu and for assessment of changes of physical chemical properties of the cytoplasm evoked by diverse stimuli including osmotic stress.

[The search for a sensor of intracellular sodium involved in pathogenesis of hypertensive disease].

Na+,K+ ATPase plays the key role in regulation of intracellular concentration of monovalent cations and related functions essential for electrogenesis and the maintenance of cell volume. This review is focused on the new data showing that a long-term increase of the intracellular Na+ level induces expression of early response genes and genes involved in regulation of apoptosis. Results of the studies of the Na+ sensor and its role in pathogenesis of the salt-sensitive form of hypertensive disease are summarized.

[What is pathophysiology nowadays? The reflections of the participants of ISP-2010 Congress in Montreal].

The main tendencies in the development of Pathophysiology as a science and teaching discipline are analyzed in the light of last 6th ISP-2010 Congress. The witnesses for the growing integration between Pathophysiology and other basic medical sciences are given, along with the preserved specifics of the pathophysiological knowledge on the etiology, pathogenesis and models of the diseases and pathological processes. The current role and place of Pathophysiology as Systemic Pathobiology within the structure of medical sciences are discussed.

Low-frequency magnetic radiation leads to the broadening of valent bonds in protein infrared spectra.

In recent years it has been discovered that a long-term exposure to low frequency magnetic fields leads to changes in activity of biological systems both in vivo and in vitro. Molecular mechanisms of this phenomenon are not clear. The present work uses infrared (IR) spectroscopy to study the effect of alternating magnetic field on a structural state of purified proteins. It was revealed that a 1-h exposure of aqueous solution of bovine serum albumin (BSA) and gluten isolated from wheat to 5.75Hz magnetic field with maximum amplitude of 25mTl resulted, respectively, in a ∼1.5- and 2-fold increase of the width of the band related to the vibrations of valent bonds in the range of 3500-2750cm(-1) (p<0.05). Unlike aqueous solutions, the desiccated BSA films did not exhibit any effect of magnetic field on parameters of IR-spectra. It is suggested, that low frequency magnetic fields induce the broadening of bands in IR spectra due to changes in structural organization of delocalized protein-bound water molecules thereby affecting macromolecules and related cell reactions.