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Recchioni R, Marcheselli F, Moroni F, Gáspár R, Damjanovich S, Pieri C. Melatonin increases the intensity of respiratory burst and prevents L-selectin shedding in human neutrophils in vitro. Biochem Biophys Res Commun 1998; 252:20-4. [PMID: 9813139 DOI: 10.1006/bbrc.1998.9582] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Effects of melatonin priming of neutrophils and subsequent increase of phorbol 12-miristate 13-acetate stimulated respiratory burst were investigated on the modulation of L-selectin shedding and MAC-1 upregulation. Respiratory burst related H2O2 production and adhesion molecule expression were quantified by flow cytometry. Phorbol 12-miristate 13-acetate dose dependence of intracellular oxidation and adhesion molecule expression showed no relationship between respiratory burst intensity and MAC-1 expression or L-selectin shedding. Treatment of cells with 12.5 nM phorbol 12-miristate 13-acetate resulted in less than 20% of the respiratory burst response, however it induced 91.7% of total MAC-1 expression and 62.8% of L-selectin shedding. Melatonin priming experiments showed also no connection between the extent of respiratory burst and MAC-1 expression, however melatonin priming almost completely prevented L-selectin down-regulation elicited by phorbol 12-miristate 13-acetate, without affecting MAC-1 expression. It is suggested that melatonin may inhibit metalloproteases responsible for L-selectin cleavage.
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Damjanovich S, Matkó J, Mátyus L, Szabó G, Szöllosi J, Pieri JC, Farkas T, Gáspár R. Supramolecular receptor structures in the plasma membrane of lymphocytes revealed by flow cytometric energy transfer, scanning force- and transmission electron-microscopic analyses. CYTOMETRY 1998; 33:225-33. [PMID: 9773884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
Receptors in the plasma membrane of blood cells in general and in that of lymphocytes in particular are supposed to move around in a random walk fashion relatively freely driven by thermal diffusion, as described by the Singer-Nicolson fluid mosaic membrane model. In this article we summarized data and techniques that indicated nonrandom codistribution patterns of receptor superstructures under conditions, where the generation of such molecular colocalizations by the methods themselves were excluded. Application of fluorescence energy transfer in a flow cytometer helped to analyze such codistribution patterns in cell populations. After normalizing energy transfer values for possible differences between labeling ratios of the targeting monoclonal antibodies and using the mean values of energy transfer distribution curves, two-dimensional receptor maps were generated from data obtained in a pair-wise fashion between receptors. Major histocompatibility complex (MHC) class I and II, intercellular adhesion molecule-1 (ICAM-1), TcR-CD3-CD4, tetraspan molecules (CD81, CD82, CD53), and the subunits of the multisubunit IL-2 receptor displayed nonrandom codistribution patterns sometimes with, but very frequently without induction by their ligand. Immunogold-bead "sandwich" labeling analyzed by atomic force microscopy has shown that such receptor "islands" existed also in "receptor-island-groups". This indicated the existence of nonrandom receptor distribution of MHC class I and II molecules also at an elevated hierarchical level. An analysis is given herein concerning a standardized approach. The apparent incompatibility of these supramolecular patterns with the Singer-Nicolson type "free-protein and lipid-mobility paradigm" was resolved by recommending an additional emphasis on the mosaicism of the membrane besides receptor mobility.
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MESH Headings
- Antibodies, Monoclonal/immunology
- Antigens, CD/analysis
- Diffusion
- Energy Transfer
- Flow Cytometry
- Fluorescence
- Fluorescent Dyes
- HLA Antigens/analysis
- Humans
- Immunoglobulin Fab Fragments/immunology
- Immunohistochemistry
- Intercellular Adhesion Molecule-1/analysis
- Lymphocytes/chemistry
- Macromolecular Substances
- Membrane Fluidity
- Microscopy, Atomic Force
- Microscopy, Electron
- Microspheres
- Models, Biological
- Motion
- Receptor-CD3 Complex, Antigen, T-Cell/analysis
- Receptors, Cell Surface/analysis
- Receptors, Interleukin-2/analysis
- Tumor Cells, Cultured
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Zupkó I, Márki A, Gáspár R, Falkay G. Correlation between alpha1/beta-adrenoceptor ratio and spontaneous uterine motor activity in the post-partum rat. Mol Hum Reprod 1998; 4:921-4. [PMID: 9783855 DOI: 10.1093/molehr/4.9.921] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The spontaneous uterine motor activity of the post-partum rat was investigated in parallel with the in-vitro determination of the density of the alpha1 and beta-adrenergic receptors of the myometrium. The in-vivo experiments were performed by an improved method, using a Millar catheter fitted with a latex microballoon. The spontaneous contractility of the post-partum rat uterus was found to be highest 24 h after delivery, indicating that this time is the most suitable for pharmacological examinations of tocolytic agents. A very close correlation was found between the results of the in-vivo experiments and the alpha1/beta-adrenergic receptor ratio assessed by an in-vitro receptor assay, thus indicating that the state of the adrenergic receptor system fundamentally determines the contractility of the uterus. This conclusion is supported by the fact that the pharmacological sensitivity of the rat uterus to prazosin and fenoterol changed as a function of the post-partum time in accordance with the alpha1/beta-adrenoceptor ratio. These results and the relevant data available reveal a crucially important role of an alpha1-adrenoceptor-mediated process, implicating alpha1-blockers as theoretically potent agents for inhibition of premature uterine contractions.
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Gáspár R, Márki A, Zupkó I, Falkay G. Evidence of non-synaptic regulation of postpartum uterine contractility in the rat. Life Sci 1998; 62:1119-24. [PMID: 9519814 DOI: 10.1016/s0024-3205(98)00035-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Myometrial tissue rings from postpartum rats (24 h after delivery) were studied in vitro by electric field stimulation, and the alpha1/beta2-adrenoceptor ratio was determined by a radioligand binding technique. Pregnancy-denervated uterine rings were stimulated by long-duration pulses (100 ms). The contractions were inhibited by beta2-agonists (terbutaline and fenoterol) and alpha-antagonists (phentolamine, urapidil and yohimbine) in a concentration-dependent manner. Their effects were not altered by the adrenergic neuron-blocking agent bretylium. The alpha-antagonists (except phentolamine) elicited the same maximal inhibition as the beta2-agonists. Receptor assays revealed that the alpha1/beta2 ratio was about 2 in the measured uteri. It was concluded that the inhibitory effects of alpha-antagonists and beta2-agonists are mediated via non-synaptic adrenoceptors of the denervated postpartum rat uterus. The same inhibitory activity could be explained by the greater amount of alpha-receptors. It is believed that this is the first functional proof of the existence of non-synaptic alpha1-adrenoceptors in smooth muscle.
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Péter M, Varga Z, Panyi G, Bene L, Damjanovich S, Pieri C, Possani LD, Gáspár R. Pandinus imperator scorpion venom blocks voltage-gated K+ channels in human lymphocytes. Biochem Biophys Res Commun 1998; 242:621-5. [PMID: 9464266 DOI: 10.1006/bbrc.1997.8018] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Using the patch-clamp technique, we determined that Pandinus imperator scorpion venom blocked whole-cell n-type K+ currents in human peripheral blood lymphocytes in a dose-dependent manner with Kd = 0.02 microgram/ml. K+ channel block was instantaneous and removable by washing with venom-free extracellular solution. The venom-induced block was independent of membrane potential. The venom did not influence activation and inactivation kinetics of the K+ channels, however, accelerated recovery from inactivation. Purified peptides Pi1, Pi2, and Pi3 from the P. imperator venom powerfully blocked Kv1.3 channels in human lymphocytes with Kd values of 9.7 nM, 50 pM, and 0.5 nM, respectively. Flow cytometric membrane potential measurements with the oxonol dye showed that Pi2, the most effective peptide toxin of the P. imperator venom, depolarizes human lymphocytes in accordance with its K+ channel blocking effect.
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Zupkó I, Gáspár R, Kovács L, Falkay G. Are alpha-adrenergic antagonists potent tocolytics? In vivo experiments on postpartum rats. Life Sci 1997; 61:PL 159-63. [PMID: 9307057 DOI: 10.1016/s0024-3205(97)00619-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The aim of this study was to investigate the effects of alpha-adrenergic antagonists on the motor activity of the postpartum uterus of the rat in vivo. Intrauterine pressure was assessed by means of a Millar catheter fitted with a latex microballoon. Some of the tested compounds (urapidil, yohimbine, phentolamine, benoxathian and prazosin) decreased the uterine activity to a significant extent (57.4-67.4%). However, none of the investigated alpha receptor blockers exerted the same effect as beta-adrenergic agonists. Our results suggest that alpha-adrenergic antagonists could possibly be used as an alternative to beta-adrenergic agonists in clinical tocolysis after an appropriate clinical evaluation.
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Jenei A, Varga S, Bene L, Mátyus L, Bodnár A, Bacsó Z, Pieri C, Gáspár R, Farkas T, Damjanovich S. HLA class I and II antigens are partially co-clustered in the plasma membrane of human lymphoblastoid cells. Proc Natl Acad Sci U S A 1997; 94:7269-74. [PMID: 9207080 PMCID: PMC23810 DOI: 10.1073/pnas.94.14.7269] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Major histocompatibility complex (MHC) class II molecules displayed clustered patterns at the surfaces of T (HUT-102B2) and B (JY) lymphoma cells characterized by interreceptor distances in the micrometer range as detected by scanning force microscopy of immunogold-labeled antigens. Electron microscopy revealed that a fraction of the MHC class II molecules was also heteroclustered with MHC class I antigens at the same hierarchical level as described by the scanning force microscopy data, after specifically and sequentially labeling the antigens with 30- and 15-nm immunogold beads. On JY cells the estimated fraction of co-clustered HLA II was 0.61, whereas that of the HLA I was 0.24. Clusterization of the antigens was detected by the deviation of their spatial distribution from the Poissonian distribution representing the random case. Fluorescence resonance energy transfer measurements also confirmed partial co-clustering of the HLA class I and II molecules at another hierarchical level characterized by the 2- to 10-nm Förster distance range and providing fine details of the molecular organization of receptors. The larger-scale topological organization of the MHC class I and II antigens may reflect underlying membrane lipid domains and may fulfill significant functions in cell-to-cell contacts and signal transduction.
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Bene L, Szöllósi J, Balázs M, Mátyus L, Gáspár R, Ameloot M, Dale RE, Damjanovich S. Major histocompatibility complex class I protein conformation altered by transmembrane potential changes. CYTOMETRY 1997; 27:353-7. [PMID: 9098627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The nature of charge distributions in membrane-bound macromolecular structures renders them susceptible to interaction with transmembrane potential fields. As a result, conformational changes in such species may be expected to occur when this potential is altered. We have detected reversible conformational change in the major histocompatibility complex (MHC) class I antigen in the plasma membrane of human JY cells, as monitored by flow-cytometric resonance energy-transfer, upon reduction of the transmembrane potential (depolarization). This change increased the intramolecular energy-transfer efficiency between fluorescent donor- and acceptor-labeled monoclonal antibodies directed, respectively, to epitopes on the light (beta 2-microglobulin) and the heavy chains of the MHC class I antigen. Repolarization of the depolarized samples restored the energy-transfer efficiency to the original values measured before depolarization. Depolarization caused similar relative changes in fluorescence resonance energy-transfer efficiency when Fab fragments were used for labeling MHC class I complex, suggesting that the observed phenomenon is not restricted to whole monoclonal antibodies.
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Abstract
1. INTRODUCTION 681.1 Receptor patterns in the plasma membrane 681.2 Different types of receptor patterns 712. METHODS TO INVESTIGATE NON-RANDOM RECEPTOR CLUSTERING 732.1 Fluorescence resonance energy transfer 732.2 Flow cytometric energy transfer measurement 782.3 Fluorescence anisotropy and energy transfer 792.4 Photobleaching energy transfer on single cells 812.5 Two-dimensional mapping of receptor superstructures 822.6 Detecting single receptor molecules 852.7 Chemical identification of receptor clusters 862.8 Electron microscopy 872.9 Scanning force microscopy 883. CONFORMATIONAL STATES OF RECEPTORS 903.1 Multi-subunit receptor structures 903.2 Physical parameters influencing conformational states 913.3 Chemical interactions and receptor conformations 924. ON THE ORIGIN OF NATURALLY OCCURRING RECEPTOR CLUSTERS 934.1 Synthesis of receptors and their localization in the plasma membrane
934.2 Lipid domain structure of the plasma membrane 944.3 The validity of the Singer–Nicolson model 945. CONCLUSIONS 966. ACKNOWLEDGEMENTS 967. REFERENCES 97
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Gáspár R, Varga Z, Bene L, Marcheselli F, Pieri C, Damjanovich S. Effect of acetylcholine on the electrophysiology and proliferative response of human lymphocytes. Biochem Biophys Res Commun 1996; 226:303-8. [PMID: 8806630 DOI: 10.1006/bbrc.1996.1351] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Using the patch-clamp technique, we determined that 1-15 mM extracellular acetylcholine reduced whole-cell n-type K+ currents in human peripheral blood lymphocytes and accelerated their inactivation. The percentage increase in K+ channel inactivation rate and the degree of drug induced block were independent of membrane potential. In flow cytometric membrane potential measurements with the oxonol dye similar doses of acetylcholine depolarized the lymphocyte population. Both acetylcholine induced K+ channel block and depolarization fully developed within 2 minutes. The depolarizing and K+ channel blocking effects of acetylcholine are in concert. [3H]thymidine incorporation experiments proved that the proliferative response of PHA stimulated peripheral blood lymphocytes was decreased by increasing concentrations of acetylcholine in the 1-50 mM range.
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Gáspár R, Blazsó G. [Effects pf captopril and D-penicillamine on kinins-mediated and chronic inflammation]. ACTA PHARMACEUTICA HUNGARICA 1996; 66:171-6. [PMID: 9082838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
In our study the effects of angiotension converting enzyme inhibitor captopril and immunosuppressant agent d-penicillamine were investigated on inflammations mediated by kinins and on adjuvant arthritis in rat paw oedema tests. Kinins mediated inflammations were increased by small doses of captopril (0.04-5 mg/kg per os) in a dose dependent manner. However this effect of captopril was reduced at higher doses of the drug (5-400 mg/kg). In the case of d-penicillamine there was exerted an inflammation increasing effect similarly to captopril. Maximum value of this action could be measured at dose 100 mg/kg per os. After administration higher doses of d-penicillamine were not revealed any depression in inflammation increasing effect. In capillary resistance studies we have shown capillary resistance increasing action of captopril that was dose depend. However this effect was not found in the case of d-penicillamine. According to these finding kinins mediated inflammation increasing effects of captopril and d-penicillamine are suggested as a results of their ability inhibit angiotensin converting enzyme. Maximum depression at higher doses of captopril may be caused by its capillary resistance elevating action. In chronic inflammations studies we have shown developments of secondary symptoms of adjuvant arthritis inhibiting effects of captopril and d-penicillamine in a dose dependent manner. We assume that immunosuppressive action of both drug are responsible for reduction of chronic inflammations. Our study strengthens the argument that captopril can be used in therapy of rheumatoid arthritis. Further clinicopharmacological studies of captopril may clarify the role of this drug in therapy of rheumatoid diseases.
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Bacsó Z, Matkó J, Szöllõsi J, Gáspár R, Damjanovich S. Changes in membrane potential of target cells promotes cytotoxic activity of effector T lymphocytes. Immunol Lett 1996; 51:175-80. [PMID: 8832288 DOI: 10.1016/0165-2478(96)02573-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The effector function of CD8+ lymphocytes depends on recognition by the TcR-CD3 complex of an oligopeptide presented by an MHC class I molecule on target cells. Recently it has been shown that MHC class I molecules change their conformation upon depolarization of human B lymphoblastoid JY cells. We studied here the effects of changes in membrane potential of target cells on the function of cytotoxic T lymphocytes (CTL). Selective alterations of plasma membrane potential of JY target cells were achieved by treatments with specific ionophore molecules as well as with Na(+)-K(+)-ATPase inhibitor, while the cytotoxic lymphocytes were not influenced. The plasma membrane was depolarized by gramicidin D and ouabain, while hyperpolarization was induced by valinomycin treatment. Alterations of the resting membrane potential of target cells in both direction resulted in an enhanced cytotoxic activity. The observed changes in cytolytic activities of cytotoxic T effectors may have a more general biological significance, namely apoptotic cells become depolarized after a given time, moreover neoplastic and virus infected cells also frequently show decreased membrane potential. A more efficient recognition of these cells by CTL is supposed to enhance the efficiency of their elimination, as well.
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Pieri C, Marra M, Gáspár R, Damjanovich S. Melatonin protects LDL from oxidation but does not prevent the apolipoprotein derivatization. Biochem Biophys Res Commun 1996; 222:256-60. [PMID: 8670192 DOI: 10.1006/bbrc.1996.0731] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Protective effect of melatonin against Cu++ induced peroxidative modification of low density lipoprotein (LDL) was studied in vitro. Melatonin was used for this purpose because of its known scavenging capacity against hydroxyl and peroxyl radicals. It was demonstrated by the diene formation kinetic analysis that melatonin protected polyunsaturated fatty acids of LDL lipids against peroxidation. Lag time duration was prolonged, peak time was delayed, whereas rate of diene formation was decreased in melatonin treated LDL; however, parameters related to apolipoprotein (apo-B) showed that the protein was derivatized. Fluorescence, relative electrophoretic mobility, lysine residues analysis data, as well as the uptake by macrophages all showed properties similar to those of oxidised LDL. Present data suggest that by-products of melatonin oxidation might react with lysine residues of apo-B, transforming LDL in its atherogenic form.
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Varga Z, Bene L, Pieri C, Damjanovich S, Gáspár R. The effect of juglone on the membrane potential and whole-cell K+ currents of human lymphocytes. Biochem Biophys Res Commun 1996; 218:828-32. [PMID: 8579599 DOI: 10.1006/bbrc.1996.0147] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Using flow cytometric membrane potential measurements with the oxonol dye, we determined that 5.7-57 microM juglone depolarizes human lymphocytes in a dose dependent manner. The depolarizing effect of juglone was verified by patch-clamp. Juglone decreased whole-cell n-type K+ currents in human peripheral blood lymphocytes and accelerated inactivation; however, it did not influence the kinetics of activation of the K+ conductance. The percentage increase in K+ channel inactivation rate and the degree of drug induced block was independent of membrane potential, K+ channel block by juglone fully developed within 4 minutes and was not removable by washing with drug free extracellular solution. Blocking of n-type K+ channels by juglone is in concert with its depolarizing effect on human lymphocytes.
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Gáspár R, Bene L, Damjanovich S, Muñoz-Garay C, Calderon-Aranda ES, Possani LD. Beta-scorpion toxin 2 from Centruroides noxius blocks voltage-gated K+ channels in human lymphocytes. Biochem Biophys Res Commun 1995; 213:419-23. [PMID: 7646494 DOI: 10.1006/bbrc.1995.2148] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Using the patch-clamp technique, we determined that beta-scorpion toxin 2 from Centruroides noxius Hoffmann decreased whole-cell n-type K+ currents in human peripheral blood lymphocytes, with a half blocking concentration of approx. 5 microM. Toxin-2-accelerated inactivation, however, did not influence the kinetics of activation of the K+ conductance. The percentage increase in K+ channel inactivation rate and the degree of drug-induced block was independent of membrane potential. K+ channel block by Toxin 2 was instantaneous, not removable by washing with drug free extracellular solution. However, 10 mg/ml BSA in the bath lifted the toxin-induced block almost instantaneously and completely. Flow cytometric membrane potential measurements with the oxonol dye showed that Toxin 2 depolarizes human lymphocytes in concert with its K+ channel blocking effect.
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Gáspár R, Weidema AF, Krasznai Z, Nijweide PJ, Ypey DL. Tetrodotoxin-sensitive fast Na+ current in embryonic chicken osteoclasts. Pflugers Arch 1995; 430:596-8. [PMID: 7491289 DOI: 10.1007/bf00373899] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
A voltage-dependent, fast, transient inward current was characterized in embryonic chicken osteoclasts using the permeabilized patch configuration of the patch-clamp technique. The current was activated by depolarizations to higher than -28 +/- 4 mV from a holding potential of -80 mV. It peaked within 1-1.5 ms, and inactivated within 3.3-6.9 ms. The 50% inactivation voltage was -59 +/- 6 mV with a steepness factor of 0.11 +/- 0.06. The current disappeared with the removal of extracellular Na+ and was reversibly blocked by tetrodotoxin (K0.5 < 15 nM) but not by verapamil (< or = 100 microM). We conclude that this new current in embryonic chicken osteoclasts is a sodium current known from excitable cells.
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Vereb G, Mátyus L, Bene L, Panyi G, Bacsó Z, Balázs M, Matkó J, Szöllösi J, Gáspár R, Damjanovich S. Plasma-membrane-bound macromolecules are dynamically aggregated to form non-random codistribution patterns of selected functional elements. Do pattern recognition processes govern antigen presentation and intercellular interactions? J Mol Recognit 1995; 8:237-46. [PMID: 8588941 DOI: 10.1002/jmr.300080402] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Molecular recognition processes between cell surface elements are discussed with special reference to cell surface pattern formation of membrane-bound integral proteins. The existence, as detected by flow cytometric resonance energy transfer (Appendix), and significance of cell surface patterns involving the interleukin-2 receptor, the T-cell receptor-CD3 system, the intercellular adhesion molecule ICAM-1, and the major histocompatibility complex class I and class II molecules in the plasma membrane of lymphocytes are described. The modulation of antigen presentation by transmembrane potential changes is discussed, and a general role of transmembrane potential changes, and therefore of ion channel activities, adduced as one of the major regulatory mechanisms of cell-cell communication. A general role in the mediation and regulation of intercellular interactions is suggested for cell-surface macromolecular patterns. The dynamic pattern of protein and lipid molecules in the plasma membrane is generated by the genetic code, but has a remarkable flexibility and may be one of the major instruments of accommodation and recognition processes at the cellular level.
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Nagy P, Panyi G, Jenei A, Bene L, Gáspár R, Matkó J, Damjanovich S. Ion-channel activities regulate transmembrane signaling in thymocyte apoptosis and T-cell activation. Immunol Lett 1995; 44:91-5. [PMID: 7797261 DOI: 10.1016/0165-2478(94)00198-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Several examples have shown that plasma membrane ion channels (e.g., Ca2+ and K+ channels) make an important contribution to lymphocyte activation or thymocyte apoptosis. Here we report on the importance of these ion channels in the sensitivity or resistance of lymphoid cells to extracellular ATP-induced apoptosis. Thymocytes of Balb/c mice responded to extracellular ATP (ATPex) sensitively, with an immediate increase in the intracellular calcium level and later with an increased membrane permeability to low MW markers. Mature (medullary) thymocytes showed a higher sensitivity than did cortical thymocytes. Three human lymphoma cell lines, including SUPT13, a cell line reported to be sensitive to TcR/CD3 activation-induced apoptosis, showed a high resistance to ATPex action. These observations suggest that maturation/differentiation state-dependent activity or disappearance of early ATP-receptor operated signaling systems (including ion channels) are critical for the cells in developing towards apoptosis. Using the patch-clamp technique we demonstrated that bretylium tosylate (a particular K(+)-channel blocker) known as inhibitor of T-lymphocyte proliferation also influences the single-channel properties of voltage-gated K+ channels through depressing whole-cell K+ currents. This finding is yet another example underlying the importance of K+ channel activity in T-lymphocyte proliferation.
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Gáspár R, Panyi G, Ypey DL, Krasznai Z, Vereb G, Pieri C, Damjanovich S. Effects of bretylium tosylate on voltage-gated potassium channels in human T lymphocytes. Mol Pharmacol 1994; 46:762-6. [PMID: 7969057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Using the patch-clamp technique, we determined that bretylium tosylate, a quaternary ammonium compound possessing immunomodulating activity, decreased the whole-cell K+ current in human T lymphocytes, in a dose-dependent manner, in the 0.05-5 mM extracellular concentration range. Bretylium tosylate prolonged the recovery from inactivation and accelerated the inactivation and deactivation of the K+ current but did not influence the kinetics of activation or the voltage dependence of activation and steady state inactivation of the K+ conductance. The percentage of drug-induced block was independent of membrane potential. K+ channel block by bretylium tosylate was partially and slowly removable by washing with drug-free extracellular solution. Bovine serum albumin (10 mg/ml) in the bath lifted the drug-induced block almost instantaneously, although not completely. In control experiments bovine serum albumin increased the inactivation time constant of the K+ channels but left the peak K+ current amplitude unaffected. On the basis of the experimental evidence, a gating-dependent allosteric interaction is suggested for the mechanism of drug action. The effective dose range, time of exposure, and reversibility of bretylium tosylate-induced K+ channel block correlated well with the same parameters of the drug-induced inhibition of T lymphocyte activation. The reported effects of bretylium tosylate on T cell mitogenesis can be regarded partly as a consequence of its blocking effects on voltage-gated K+ channels.
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Panyi G, Berecki G, Gáspár R, Seres I, Fülöp T, Damjanovich S. Peripheral blood lymphocytes display reduced K+ channel activity in aged humans. Biochem Biophys Res Commun 1994; 199:519-24. [PMID: 8135792 DOI: 10.1006/bbrc.1994.1259] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Steady-state parameters of whole-cell K+ current have been determined in human peripheral blood lymphocytes of young (20-50 y.) and elderly (> 90 y.) volunteers by patch-clamp. The magnitude and voltage dependence of the K+ conductance were similar in both lymphocyte populations. The midpoint of steady-state inactivation was -53.3 +/- 2.3 mV for lymphocyte population of young individuals and -65.0 +/- 3.0 mV for that of elderly, showing a significant shift to hyperpolarized potentials. The peak of the steady-state open probability of the K+ channels was decreased and shifted to depolarized potentials by approx. 12.5 mV for lymphocytes of elderly donors. It is suggested that the observed differences in the K+ current parameters may be at least partly responsible for the impaired responsiveness of elderly lymphocytes to proliferative stimuli.
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46
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Pieri C, Bacsó Z, Recchioni R, Moroni F, Balázs M, Gáspár R, Damjanovich S. Bretylium differentiates between distinct signal transducing pathways in human lymphocytes. Biochem Biophys Res Commun 1993; 190:654-9. [PMID: 8427605 DOI: 10.1006/bbrc.1993.1098] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The selection of signal transducing pathways of T cells depends on the type of triggers. Antigens, antibodies or lectins induce the T cell receptor-CD3 operated pathway, and IL-2 transmits its activation signal via the IL-2 receptor. It has been demonstrated that bretylium, a quaternary ammonium ion, can significantly inhibit the first pathway at the same dose range that stimulates cell activation through the IL-2 receptor system. In the light of the different complexity of the two pathways at the plasma membrane level, and the non-toxic and reversible behavior of the drug, it is suggested that the bretylium induced sustained membrane hyperpolarization is responsible for the observation. This finding may open new possibilities in studying the mechanism of different signal transducing pathways.
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Gáspár R, Krasznai Z, Márián T, Trón L, Recchioni R, Falasca M, Moroni F, Pieri C, Damjanovich S. Bretylium-induced voltage-gated sodium current in human lymphocytes. BIOCHIMICA ET BIOPHYSICA ACTA 1992; 1137:143-7. [PMID: 1329976 DOI: 10.1016/0167-4889(92)90195-h] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Using the whole-cell variation of the patch-clamp technique it has been determined that 0.25-3 mM bretylium tosylate (BT) exerts a repolarizing effect on partially depolarized human lymphocytes. The repolarizing effect was ouabain (40 microM)-sensitive, and was inhibited by the removal of external Na+ or by the Na(+)-channel-blocker amiloride (10-44 microM), but K(+)-channel-blockers 4-aminopyridine (0.1-5 mM) and quinine (100 microM) had no effect. The drug induced a sodium dependent, amiloride-sensitive transient inward current reaching its maximum value approx. 20-30 s after the administration of BT and lasting for 6-10 min. This current was activated by depolarization within 25 ms at around -42 mV, its inactivation took about 2 s and its reversal potential was +24 +/- 5 mV. An increase in the intracellular sodium concentration (1.8-3.2 mM) has been observed upon the addition of BT by monitoring the SBFI fluorescence of the dye-loaded cells. It has been shown that whole-cell K+ currents are significantly decreased by BT. The existence of voltage and ligand (BT)-gated sodium channels has been postulated in human lymphocytes. These channels are thought to participate in the initiation of membrane repolarization in human lymphocytes, and thereby influence mitogenic or antigen-induced cell-activation processes.
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Damjanovich S, Mátyus L, Balázs M, Gáspár R, Krasznai Z, Pieri C, Szöllösi J, Trón L. Dynamic physical interactions of plasma membrane molecules generate cell surface patterns and regulate cell activation processes. Immunobiology 1992; 185:337-49. [PMID: 1452209 DOI: 10.1016/s0171-2985(11)80651-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Molecular interaction and transmembrane signal transducing events generate a very dynamic and ever changing "pattern" in the plasma membranes. Lymphocytes, the key functional elements of the immune system, are eminently suited to be the primary targets to investigate these proximity, mobility, or other physical-chemical changes in their plasma membranes. Recently, a number of experiments suggested that processed peptides from antigens can bind specific components of MHC molecules (Elliott et al., 1991). This is certainly a way to alter their structure. Cell surface patterns of topological nature, assembly and disassembly of oligomeric receptor structure like the IL-2 receptor have been investigated by sophisticated biophysical techniques. The dynamic changes in the two-dimensional cell surface pattern and intramolecular conformational changes within this "larger" macro-pattern may have a strong regulatory role in signal transducing and intercellular recognition processes. Recent data on these problems are presented together with brief and critical discussions.
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Pieri C, Recchioni R, Moroni F, Marcheselli F, Falasca M, Krasznai Z, Gáspár R, Mátyus L, Damjanovich S. A sodium channel opener inhibits stimulation of human peripheral blood mononuclear cells. Mol Immunol 1992; 29:517-24. [PMID: 1565099 DOI: 10.1016/0161-5890(92)90009-m] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The role of membrane potential changes in T cell activation was studied on human peripheral blood lymphocytes stimulated with phytohemagglutinin. Addition of bretylium tosylate, a sodium channels opener, to PHA treated lymphocytes modified the membrane potential and consequently blocked cell activation in a dose-dependent fashion. BT was non-toxic even in long-term (72 hr) incubations. It was reversibly removable, and the removal restored the stimulatory effect of PHA. 3H-thymidine incorporation was blocked if BT was present during the first 20-24 hr of the mitogenic activation. The later BT was added after PHA, the less inhibition of proliferation was observed. BT hyperpolarized the lymphocytes also in the presence of PHA. BT hindered the depolarizing effect of high extracellular potassium concns. The sustained polarized state of the lymphocytes did not influence the intracellular calcium increase upon PHA treatment. IL-2 and transferrin receptor expression was not hindered by BT during PHA stimulation of lymphocytes. Addition of rIL-2 did not abolish the inhibitory effect of BT. According to cell-cycle analysis BT arrested the majority of the cells in G1 phase. It is suggested that cell activation demands the flexible maintenance of a relatively narrow membrane potential "window". Any sustained and significant hyper-, or depolarization, may dramatically decrease the effectivity of transmembrane signalling.
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Gáspár R, Nagy Á. The first ionization energy, electron affinity and electronegativity calculated by theX α method with ab initio self-consistent exchange parameter. ACTA ACUST UNITED AC 1988. [DOI: 10.1007/bf03053845] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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