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Orlov SN, Tverskoi AM, Sidorenko SV, Smolyaninova LV, Lopina OD, Dulin NO, Klimanova EA. Na,K-ATPase as a target for endogenous cardiotonic steroids: What's the evidence? Genes Dis 2020; 8:259-271. [PMID: 33997173 PMCID: PMC8093582 DOI: 10.1016/j.gendis.2020.01.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 12/24/2019] [Accepted: 01/09/2020] [Indexed: 12/17/2022] Open
Abstract
With an exception of few reports, the plasma concentration of ouabain and marinobufagenin, mostly studied cardiotonic steroids (CTS) assessed by immunoassay techniques, is less than 1 nM. During the last 3 decades, the implication of these endogenous CTS in the pathogenesis of hypertension and other volume-expanded disorders is widely disputed. The threshold for inhibition by CTS of human and rodent α1-Na,K-ATPase is ∼1 and 1000 nM, respectively, that rules out the functioning of endogenous CTS (ECTS) as natriuretic hormones and regulators of cell adhesion, cell-to-cell communication, gene transcription and translation, which are mediated by dissipation of the transmembrane gradients of monovalent cations. In several types of cells ouabain and marinobufagenin at concentrations corresponding to its plasma level activate Na,K-ATPase, decrease the [Na+]i/[K+]i-ratio and increase cell proliferation. Possible physiological significance and mechanism of non-canonical Na+i/K+i-dependent and Na+i/K+i-independent cell responses to CTS are discussed.
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Affiliation(s)
- Sergei N Orlov
- MV Lomonosov Moscow State University, Moscow, 119234, Russia.,National Research Tomsk State University, Tomsk, 634050, Russia.,Siberian State Medical University, Tomsk, 634050, Russia
| | | | - Svetlana V Sidorenko
- MV Lomonosov Moscow State University, Moscow, 119234, Russia.,National Research Tomsk State University, Tomsk, 634050, Russia
| | - Larisa V Smolyaninova
- MV Lomonosov Moscow State University, Moscow, 119234, Russia.,National Research Tomsk State University, Tomsk, 634050, Russia
| | - Olga D Lopina
- MV Lomonosov Moscow State University, Moscow, 119234, Russia
| | | | - Elizaveta A Klimanova
- MV Lomonosov Moscow State University, Moscow, 119234, Russia.,National Research Tomsk State University, Tomsk, 634050, Russia
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Abstract
Myofibroblast activation is a critical process in the pathogenesis of tissue fibrosis accounting for 45% of all deaths. No effective therapies are available for the treatment of fibrotic diseases. We focus our mini-review on recent data showing that cardiotonic steroids (CTS) that are known as potent inhibitors of Na+,K+-ATPase affect myofibroblast differentiation in a cell type-specific manner. In cultured human lung fibroblasts (HLF), epithelial cells, and cancer-associated fibroblasts, CTS blocked myofibroblast differentiation triggered by profibrotic cytokine TGF-β. In contrast, in the absence of TGF-β, CTS augmented myofibroblast differentiation of cultured cardiac fibroblasts. The cell type-specific action of CTS in myofibroblast differentiation is consistent with data obtained in in vivo studies. Thus, infusion of ouabain via osmotic mini-pumps attenuated the development of lung fibrosis in bleomycintreated mice, whereas marinobufagenin stimulated renal and cardiac fibrosis in rats with experimental renal injury. In TGF-β-treated HLF, suppression of myofibroblast differentiation by ouabain is mediated by elevation of the [Na+]i/[K+]i ratio and is accompanied by upregulation of cyclooxygenase COX-2 and downregulation of TGF-β receptor TGFBR2. Augmented expression of COX-2 is abolished by inhibition of Na+/Ca2+ exchanger, suggesting a key role of [Ca2+]i-mediated signaling. What is the relative impact in tissue fibrosis of [Na+]i,[K+]iindependent signaling documented in several types of CTS-treated cells? Do the different conformational transitions of Na+,K+-ATPase α1 subunit in the presence of ouabain and marinobufagenin contribute to their distinct involvement in myofibroblast differentiation? Additional experiments should be done to answer these questions and to develop novel pharmacological approaches for the treatment of fibrosis-related disorders.
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Affiliation(s)
- Sergei N. Orlov
- Faculty of Biology, Lomonosov Moscow State University, Russian Federation
| | - Jennifer La
- Department of Medicine, The University of Chicago, IL, United States
| | | | - Nickolai O. Dulin
- Department of Medicine, The University of Chicago, IL, United States
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Na⁺ i,K⁺ i-Dependent and -Independent Signaling Triggered by Cardiotonic Steroids: Facts and Artifacts. Molecules 2017; 22:molecules22040635. [PMID: 28420099 PMCID: PMC6153942 DOI: 10.3390/molecules22040635] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 03/31/2017] [Accepted: 04/11/2017] [Indexed: 11/17/2022] Open
Abstract
Na⁺,K⁺-ATPase is the only known receptor of cardiotonic steroids (CTS) whose interaction with catalytic α-subunits leads to inhibition of this enzyme. As predicted, CTS affect numerous cellular functions related to the maintenance of the transmembrane gradient of monovalent cations, such as electrical membrane potential, cell volume, transepithelial movement of salt and osmotically-obliged water, symport of Na⁺ with inorganic phosphate, glucose, amino acids, nucleotides, etc. During the last two decades, it was shown that side-by-side with these canonical Na⁺i/K⁺i-dependent cellular responses, long-term exposure to CTS affects transcription, translation, tight junction, cell adhesion and exhibits tissue-specific impact on cell survival and death. It was also shown that CTS trigger diverse signaling cascades via conformational transitions of the Na⁺,K⁺-ATPase α-subunit that, in turn, results in the activation of membrane-associated non-receptor tyrosine kinase Src, phosphatidylinositol 3-kinase and the inositol 1,4,5-triphosphate receptor. These findings allowed researchers to propose that endogenous CTS might be considered as a novel class of steroid hormones. We focus our review on the analysis of the relative impact Na⁺i,K⁺i-mediated and -independent pathways in cellular responses evoked by CTS.
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Klimanova EA, Tverskoi AM, Koltsova SV, Sidorenko SV, Lopina OD, Tremblay J, Hamet P, Kapilevich LV, Orlov SN. Time- and dose dependent actions of cardiotonic steroids on transcriptome and intracellular content of Na + and K +: a comparative analysis. Sci Rep 2017; 7:45403. [PMID: 28345607 PMCID: PMC5366943 DOI: 10.1038/srep45403] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 02/17/2017] [Indexed: 01/07/2023] Open
Abstract
Recent studies demonstrated that in addition to Na+,K+-ATPase inhibition cardiotonic steroids (CTSs) affect diverse intracellular signaling pathways. This study examines the relative impact of [Na+]i/[K+]i-mediated and -independent signaling in transcriptomic changes triggered by the endogenous CTSs ouabain and marinobufagenin (MBG) in human umbilical vein endothelial cells (HUVEC). We noted that prolongation of incubation increased the apparent affinity for ouabain estimated by the loss of [K+]i and gain of [Na+]i. Six hour exposure of HUVEC to 100 and 3,000 nM ouabain resulted in elevation of the [Na+]i/[K+]i ratio by ~15 and 80-fold and differential expression of 258 and 2185 transcripts, respectively. Neither [Na+]i/[K+]i ratio nor transcriptome were affected by 6-h incubation with 30 nM ouabain. The 96-h incubation with 3 nM ouabain or 30 nM MBG elevated the [Na+]i/[K+]i ratio by ~14 and 3-fold and led to differential expression of 880 and 484 transcripts, respectively. These parameters were not changed after 96-h incubation with 1 nM ouabain or 10 nM MBG. Thus, our results demonstrate that elevation of the [Na+]i/[K+]i ratio is an obligatory step for transcriptomic changes evoked by CTS in HUVEC. The molecular origin of upstream [Na+]i/[K+]i sensors involved in transcription regulation should be identified in forthcoming studies.
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Affiliation(s)
| | - Artem M Tverskoi
- Faculty of Biology, M. V. Lomonosov Moscow State University, Moscow, 119234, Russia
| | - Svetlana V Koltsova
- Faculty of Biology, M. V. Lomonosov Moscow State University, Moscow, 119234, Russia
| | - Svetlana V Sidorenko
- Faculty of Biology, M. V. Lomonosov Moscow State University, Moscow, 119234, Russia
| | - Olga D Lopina
- Faculty of Biology, M. V. Lomonosov Moscow State University, Moscow, 119234, Russia
| | - Johanne Tremblay
- Research Centre, University of Montreal Hospital (CRCHUM), Montreal, H2X 0A9, Canada
| | - Pavel Hamet
- Research Centre, University of Montreal Hospital (CRCHUM), Montreal, H2X 0A9, Canada
| | | | - Sergei N Orlov
- Faculty of Biology, M. V. Lomonosov Moscow State University, Moscow, 119234, Russia.,National Research Tomsk State University, Tomsk, 634050, Russia
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Tverskoi AM, Sidorenko SV, Klimanova EA, Akimova OA, Smolyaninova LV, Lopina OD, Orlov SN. Effects of ouabain on proliferation of human endothelial cells correlate with Na+,K+-ATPase activity and intracellular ratio of Na+ and K+. BIOCHEMISTRY (MOSCOW) 2016; 81:876-83. [DOI: 10.1134/s0006297916080083] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Rodrigues-Mascarenhas S, Da Silva de Oliveira A, Amoedo ND, Affonso-Mitidieri OR, Rumjanek FD, Rumjanek VM. Modulation of the immune system by ouabain. Ann N Y Acad Sci 2009; 1153:153-63. [PMID: 19236338 DOI: 10.1111/j.1749-6632.2008.03969.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Ouabain, a known inhibitor of the Na,K-ATPase, has been shown to regulate a number of lymphocyte functions in vitro and in vivo. Lymphocyte proliferation, apoptosis, cytokine production, and monocyte function are all affected by ouabain. The ouabain-binding site occurs at the alpha subunit of the enzyme. The alpha subunit plays a critical role in the transport process, and four different alpha-subunit isoforms have been described with different sensitivities to ouabain. Analysis by RT-PCR indicates that alpha1, alpha2, and alpha3 isoforms are all present in murine lymphoid cells obtained from thymus, lymph nodes, and spleen. In these cells ouabain exerts an effect at concentrations that do not induce plasma membrane depolarization, suggesting a mechanism independent of the classical inhibition of the pump. In other systems, the Na,K-ATPase acts as a signal transducer in addition to being an ion pump, and ouabain is capable of inducing the activation of various signal transduction cascades. Neither resting nor concanavalin A (Con A)-activated thymocytes had their levels of phosphorylated-extracellular signal-regulated kinase (P-ERK) modified by ouabain. However, ouabain decreased p38 phosphorylation induced by Con A in these cells. The pathway induced by ouabain in lymphoid cells is still unclear but might vary with the type and state of activation of the cell.
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Affiliation(s)
- Sandra Rodrigues-Mascarenhas
- Laboratório de Tecnologia Farmacêutica, Departamento de Fisiologia e Patologia, Universidade Federal da Paraíba, João Pessoa, Brazil
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Schenerman MA, Leister KJ, Trachtenberg DK, Racker E. Induction of system A amino acid transport through long-term treatment with ouabain: correlation with increased (Na+/K+)-ATPase activity. J Cell Physiol 1988; 135:157-62. [PMID: 2836438 DOI: 10.1002/jcp.1041350202] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Mouse embryo fibroblast cells (C3H-10T1/2) and the methylcholanthrene-transformed derivative (MCA-10T1/2) were treated with basal modified Eagle's medium (BME) containing 10% fetal bovine serum and varying concentrations of ouabain ranging from 0.05 mM to 0.7 mM for 16 h in culture. After replacing the ouabain-containing medium with Earl's balanced salts solution, System A amino acid transport activity increased from approximately 40 to 500 pmol AIB accumulated.mg protein-1.min-1 in the C3H-10T1/2 cells and from approximately 300 to 700 pmol AIB accumulated.mg protein-1.min-1 in the MCA-10T1/2 cells. The (Na+/K+)-ATPase pump activity also increased from approximately 12 to 46 nmol Rb+ accumulated.mg protein-1.min-1 in the normal cells and from approximately 20 to 42 nmol Rb+ accumulated.mg protein-1.min-1 in the transformed cells. System A and the (Na+/K+)ATPase activity were maximally increased at approximately 0.4-0.6 mM ouabain in the normal cells in contrast to the transformed cells which were maximally stimulated at a concentration of approximately 0.2 mM ouabain. This treatment with ouabain increased the [Na+]i/[K+]i as measured by atomic absorption spectroscopy, and thereby decreased the Na+ and K+ electrochemical gradients. Our data show that the internal ion gradients inverted at a lower concentration of ouabain in the transformed cells compared to the normal cells. The ouabain-induced increase in pump and System A activity shown here was used as a tool to further investigate the coordinated ion transport regulation in the control of cell growth.
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Affiliation(s)
- M A Schenerman
- Section of Biochemistry, Molecular, and Cell Biology, Cornell University, Ithaca, New York 14853
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Witkowski JM, Mysliwski A, Mysliwska J. Decrease of lymphocyte (Na+,K+)ATP-ase activity in aged people. Mech Ageing Dev 1985; 33:11-7. [PMID: 3001440 DOI: 10.1016/0047-6374(85)90105-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Activity of (Na+,K+)ATP-ase measured by means of influx of 86Rb was compared in lymphocytes from young, middle-age and old people. It was found that the (sensitive to ouabain) activity of (Na+,K+)ATPase was significantly diminished in the lymphocytes from aged subjects.
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Gallin EK, Livengood DR. Demonstration of an electrogenic Na+-K+ pump in mouse spleen macrophages. THE AMERICAN JOURNAL OF PHYSIOLOGY 1983; 245:C184-8. [PMID: 6311022 DOI: 10.1152/ajpcell.1983.245.3.c184] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The effect of ouabain on the membrane potential of cultured mouse spleen macrophages was examined. Ouabain (10(-3) M) induced a membrane depolarization (6.6 mV) in 18 of 19 cells studied that occurred within several minutes after exposure and was not associated with significant changes in current-voltage relationships. In related studies, cells were placed in K+-free medium in the cold for 2 h to block pump activity. Subsequent exposure to K+ at 37 degrees C resulted in a membrane hyperpolarization. However, addition of K+ also enhanced inward rectification. To differentiate between the effect of K+ on the Na+-K+ pump and its action on inward rectification, two types of experiments were done. Studies performed in the presence of barium, which blocks inward rectification, demonstrated a K+-induced hyperpolarization with no changes in rectification. Additional studies examined the effects of rubidium on Na+-loaded cells. Rubidium, which blocks inward rectification but substitutes for K+ in activating the Na+-K+ pump, induced membrane hyperpolarizations that were reversed by addition of ouabain. These data indicate that macrophages exhibit an electrogenic Na+-K+ pump, which probably contributes to the resting membrane potential under steady-state conditions and can be activated under conditions designed to Na+ load the cells. In addition, they demonstrate that increasing extracellular K+ enhances inward rectification in macrophages.
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Negendank W, Shaller C. The effects of temperature and ouabain on steady-state Na and K exchanges in human lymphocytes. J Cell Physiol 1982; 113:440-54. [PMID: 6294129 DOI: 10.1002/jcp.1041130313] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Cheung RK, Grinstein S, Dosch HM, Gelfand EW. Volume regulation by human lymphocytes: characterization of the ionic basis for regulatory volume decrease. J Cell Physiol 1982; 112:189-96. [PMID: 6288741 DOI: 10.1002/jcp.1041120206] [Citation(s) in RCA: 68] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The mechanism of volume regulation in hypotonic media was analysed in human peripheral blood mononuclear (PBM) cells. Electronic cell sizing showed that hypotonic swelling is followed by a regulatory volume decrease (RVD) phase. This was confirmed by both electron microscopy and by cellular water determinations. The rate of regulatory shrinking was proportional to the degree of hypotonicity in the 0.5-0.9 X isotonic range. Cell viability was only marginally affected in this range. The content of cellular K+ decreased during RVD, while Na+ content remained unchanged. Similarly, the efflux of 86Rb (used as a K+ analog) increased upon dilution, whereas 22Na efflux was not altered. 86Rb uptake was enhanced by hypotonic stress and both ouabain-sensitive and -insensitive components were affected. A ouabain-sensitive stimulation was also seen in Na+- free media. Ouabain partially inhibited RVD only if added to the cells hours before hypotonic challenge. A normal shrinking response was observed in K+-free media, and also in Na+-free media when Li+, choline+, or Tris+ were the substitutes. In high K+ or RB+ hypotonic media shrinking was absent and a second swelling phase was observed. Cs+ displayed an intermediate behavior, with shrinking observed at lower dilutions and secondary swelling at higher ones. The direction and magnitude of the response also changed when the external K+ concentration was varied and, with 50 mM K+, no regulatory volume change occurred following hypotonic stress. These findings suggest that RVD occurs largely by a passive loss of cellular K+, resulting from a selective increase in permeability to this ion. In addition, the (Na-K) pump appears to be activated upon cell swelling by a mechanism other than Na+ entry into the cell, but this activation is not essential for RVD.
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Steed AJ, Boardman KM, Delamore IW. The role of the cellular sodium pump in human granulopoiesis in vitro. Br J Haematol 1982; 51:395-403. [PMID: 6285950 DOI: 10.1111/j.1365-2141.1982.tb02795.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The specific sodium pump antagonist ouabain was used to study the effect of sodium pump inhibition on granulopoietic colony formation by normal human bone marrow cells cultured in soft agar for 7 d. Suppression of colony formation was dose-dependent and occurred at a low and reproducible concentration. The use of an extended range of concentrations (1 X 10(-19) M to 1 X 10(-4) M) revealed no additional effect. Inhibition occurred when colony formation was stimulated by either normal human white blood cells in a soft agar underlayer, or the inclusion of pre-formed colony-stimulating activity. Sensitivity to inhibition was similar under either set of conditions, the 50% inhibitory concentrations being 2.70 +/- 0.43 (SE) X 10(-8) M and 2.83 +/- 0.21 (SE) X 10(-8) M respectively. This is interpreted as showing an effect primarily on the colony-forming cells rather than on the cellular production of colony-stimulating activity. Inhibition of colony formation by ouabain was opposed by the addition of extra potassium to the culture medium, confirming that the inhibition was mediated via a perturbation of monovalent cation exchange. Inhibition by 2 X 10(-7) M ouabain appeared to be reversible by simple washing after exposure for up to 24 h, suggesting that the inhibitory effect of ouabain is not primarily cytotoxic.
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Lebon P, Commoy-Chevalier MJ, Robert-Galliot B, Chany C. Different mechanisms for alpha and beta interferon induction. Virology 1982; 119:504-7. [PMID: 6177097 DOI: 10.1016/0042-6822(82)90109-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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Szamel M, Resch K. Inhibition of lymphocyte activation by ouabain. Interference with the early activation of membrane phospholipid metabolism. BIOCHIMICA ET BIOPHYSICA ACTA 1981; 647:297-301. [PMID: 6170333 DOI: 10.1016/0005-2736(81)90258-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Activation of lymphocytes by antigens and mitogens can effectively be prevented by ouabain, a known inhibitor of (Na+ + K+)-ATPase. Recently it was shown that lowering of intracellular levels of monovalent cations is not involved in the inhibitory effect of ouabain. (Na+ + K+)-ATPase was found to be closely associated with acyl-CoA : lysophosphatidylcholine acyltransferase in the plasma membrane of lymphocytes. Both enzymes are activated as an immediate consequence of mitogen binding. Human peripheral lymphocytes were stimulated with concanavalin A. Ouabain suppressed the induction of RNA and DNA synthesis in a concentration-dependent way. Increase of RNA synthesis was suppressed only if the glycoside were added within the first hours of activation. If ouabain was added later, incorporation of uridine remained at the rate that was reached at the time of glycoside administration, pointing to an early event where ouabain may be operative. Ouabain, in a dose-dependent manner similar to that affecting RNA and DNA synthesis, inhibited the increase in the incorporation of oleate into phospholipids in stimulated lymphocytes, whereas the turnover of phospholipid fatty acids in resting lymphocytes was unaffected. Increasing extracellular K+ concentrations reversed the binding of ouabain to lymphocytes. Simultaneously, the inhibition of stimulated RNA synthesis was decreased and the inhibition of oleate incorporation was reversed. These results suggest that the suppression of lymphocyte activation by ouabain is due to the inhibition of membrane phospholipid metabolism mediated by (Na+ + K+)-ATPase.
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Functional interrelationship between (Na+ + K+)-ATPase and lysolecithin acyltransferase in plasma membranes of mitogen-stimulated rabbit thymocytes. J Biol Chem 1981. [DOI: 10.1016/s0021-9258(19)52528-5] [Citation(s) in RCA: 39] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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