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The Molecular Heterogeneity of Store-Operated Ca 2+ Entry in Vascular Endothelial Cells: The Different roles of Orai1 and TRPC1/TRPC4 Channels in the Transition from Ca 2+-Selective to Non-Selective Cation Currents. Int J Mol Sci 2023; 24:ijms24043259. [PMID: 36834672 PMCID: PMC9967124 DOI: 10.3390/ijms24043259] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 01/31/2023] [Accepted: 02/03/2023] [Indexed: 02/11/2023] Open
Abstract
Store-operated Ca2+ entry (SOCE) is activated in response to the inositol-1,4,5-trisphosphate (InsP3)-dependent depletion of the endoplasmic reticulum (ER) Ca2+ store and represents a ubiquitous mode of Ca2+ influx. In vascular endothelial cells, SOCE regulates a plethora of functions that maintain cardiovascular homeostasis, such as angiogenesis, vascular tone, vascular permeability, platelet aggregation, and monocyte adhesion. The molecular mechanisms responsible for SOCE activation in vascular endothelial cells have engendered a long-lasting controversy. Traditionally, it has been assumed that the endothelial SOCE is mediated by two distinct ion channel signalplexes, i.e., STIM1/Orai1 and STIM1/Transient Receptor Potential Canonical 1(TRPC1)/TRPC4. However, recent evidence has shown that Orai1 can assemble with TRPC1 and TRPC4 to form a non-selective cation channel with intermediate electrophysiological features. Herein, we aim at bringing order to the distinct mechanisms that mediate endothelial SOCE in the vascular tree from multiple species (e.g., human, mouse, rat, and bovine). We propose that three distinct currents can mediate SOCE in vascular endothelial cells: (1) the Ca2+-selective Ca2+-release activated Ca2+ current (ICRAC), which is mediated by STIM1 and Orai1; (2) the store-operated non-selective current (ISOC), which is mediated by STIM1, TRPC1, and TRPC4; and (3) the moderately Ca2+-selective, ICRAC-like current, which is mediated by STIM1, TRPC1, TRPC4, and Orai1.
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Negri S, Faris P, Moccia F. Reactive Oxygen Species and Endothelial Ca 2+ Signaling: Brothers in Arms or Partners in Crime? Int J Mol Sci 2021; 22:ijms22189821. [PMID: 34575985 PMCID: PMC8465413 DOI: 10.3390/ijms22189821] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 09/08/2021] [Accepted: 09/08/2021] [Indexed: 12/20/2022] Open
Abstract
An increase in intracellular Ca2+ concentration ([Ca2+]i) controls virtually all endothelial cell functions and is, therefore, crucial to maintain cardiovascular homeostasis. An aberrant elevation in endothelial can indeed lead to severe cardiovascular disorders. Likewise, moderate amounts of reactive oxygen species (ROS) induce intracellular Ca2+ signals to regulate vascular functions, while excessive ROS production may exploit dysregulated Ca2+ dynamics to induce endothelial injury. Herein, we survey how ROS induce endothelial Ca2+ signals to regulate vascular functions and, vice versa, how aberrant ROS generation may exploit the Ca2+ handling machinery to promote endothelial dysfunction. ROS elicit endothelial Ca2+ signals by regulating inositol-1,4,5-trisphosphate receptors, sarco-endoplasmic reticulum Ca2+-ATPase 2B, two-pore channels, store-operated Ca2+ entry (SOCE), and multiple isoforms of transient receptor potential (TRP) channels. ROS-induced endothelial Ca2+ signals regulate endothelial permeability, angiogenesis, and generation of vasorelaxing mediators and can be exploited to induce therapeutic angiogenesis, rescue neurovascular coupling, and induce cancer regression. However, an increase in endothelial [Ca2+]i induced by aberrant ROS formation may result in endothelial dysfunction, inflammatory diseases, metabolic disorders, and pulmonary artery hypertension. This information could pave the way to design alternative treatments to interfere with the life-threatening interconnection between endothelial ROS and Ca2+ signaling under multiple pathological conditions.
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Jernigan NL, Resta TC, Gonzalez Bosc LV. Altered Redox Balance in the Development of Chronic Hypoxia-induced Pulmonary Hypertension. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 967:83-103. [PMID: 29047083 DOI: 10.1007/978-3-319-63245-2_7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Normally, the pulmonary circulation is maintained in a low-pressure, low-resistance state with little resting tone. Pulmonary arteries are thin-walled and rely heavily on pulmonary arterial distension and recruitment for reducing pulmonary vascular resistance when cardiac output is elevated. Under pathophysiological conditions, however, active vasoconstriction and vascular remodeling lead to enhanced pulmonary vascular resistance and subsequent pulmonary hypertension (PH). Chronic hypoxia is a critical pathological factor associated with the development of PH resulting from airway obstruction (COPD, sleep apnea), diffusion impairment (interstitial lung disease), developmental lung abnormalities, or high altitude exposure (World Health Organization [WHO]; Group III). The rise in pulmonary vascular resistance increases right heart afterload causing right ventricular hypertrophy that can ultimately lead to right heart failure in patients with chronic lung disease. PH is typically characterized by diminished paracrine release of vasodilators, antimitogenic factors, and antithrombotic factors (e.g., nitric oxide and protacyclin) and enhanced production of vasoconstrictors and mitogenic factors (e.g., reactive oxygen species and endothelin-1) from the endothelium and lung parenchyma. In addition, phenotypic changes to pulmonary arterial smooth muscle cells (PASMC), including alterations in Ca2+ homeostasis, Ca2+ sensitivity, and activation of transcription factors are thought to play prominent roles in the development of both vasoconstrictor and arterial remodeling components of hypoxia-associated PH. These changes in PASMC function are briefly reviewed in Sect. 1 and the influence of altered reactive oxygen species homeostasis on PASMC function discussed in Sects. 2-4.
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Affiliation(s)
- Nikki L Jernigan
- Department Cell Biology and Physiology, Vascular Physiology Group, University of New Mexico Health Sciences Center, University of New Mexico, Albuquerque, NM, 87131, USA
| | - Thomas C Resta
- Department Cell Biology and Physiology, Vascular Physiology Group, University of New Mexico Health Sciences Center, University of New Mexico, Albuquerque, NM, 87131, USA
| | - Laura V Gonzalez Bosc
- Department Cell Biology and Physiology, Vascular Physiology Group, University of New Mexico Health Sciences Center, University of New Mexico, Albuquerque, NM, 87131, USA.
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Groschner K, Shrestha N, Fameli N. Cardiovascular and Hemostatic Disorders: SOCE in Cardiovascular Cells: Emerging Targets for Therapeutic Intervention. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 993:473-503. [PMID: 28900929 DOI: 10.1007/978-3-319-57732-6_24] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The discovery of the store-operated Ca2+ entry (SOCE) phenomenon is tightly associated with its recognition as a pathway of high (patho)physiological significance in the cardiovascular system. Early on, SOCE has been investigated primarily in non-excitable cell types, and the vascular endothelium received particular attention, while a role of SOCE in excitable cells, specifically cardiac myocytes and pacemakers, was initially ignored and remains largely enigmatic even to date. With the recent gain in knowledge on the molecular components of SOCE as well as their cellular organization within nanodomains, potential tissue/cell type-dependent heterogeneity of the SOCE machinery along with high specificity of linkage to downstream signaling pathways emerged for cardiovascular cells. The basis of precise decoding of cellular Ca2+ signals was recently uncovered to involve correct spatiotemporal organization of signaling components, and even minor disturbances in these assemblies trigger cardiovascular pathologies. With this chapter, we wish to provide an overview on current concepts of cellular organization of SOCE signaling complexes in cardiovascular cells with particular focus on the spatiotemporal aspects of coupling to downstream signaling and the potential disturbance of these mechanisms by pathogenic factors. The significance of these mechanistic concepts for the development of novel therapeutic strategies will be discussed.
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Affiliation(s)
- Klaus Groschner
- Institute of Biophysics, Medical University of Graz, Neue Stiftingtalstrasse 6/4, 8010, Graz, Austria.
| | - Niroj Shrestha
- Institute of Biophysics, Medical University of Graz, Neue Stiftingtalstrasse 6/4, 8010, Graz, Austria
| | - Nicola Fameli
- Institute of Biophysics, Medical University of Graz, Neue Stiftingtalstrasse 6/4, 8010, Graz, Austria
- Department of Anesthesiology, Pharmacology, and Therapeutics, University of British Columbia, Vancouver, BC, Canada
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Blatter LA. Tissue Specificity: SOCE: Implications for Ca 2+ Handling in Endothelial Cells. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 993:343-361. [PMID: 28900923 DOI: 10.1007/978-3-319-57732-6_18] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Many cellular functions of the vascular endothelium are regulated by fine-tuned global and local, microdomain-confined changes of cytosolic free Ca2+ ([Ca2+]i). Vasoactive agonist-induced stimulation of vascular endothelial cells (VECs) typically induces Ca2+ release through IP3 receptor Ca2+ release channels embedded in the membrane of the endoplasmic reticulum (ER) Ca2+ store, followed by Ca2+ entry from the extracellular space elicited by Ca2+ store depletion and referred to as capacitative or store-operated Ca2+ entry (SOCE). In vascular endothelial cells, SOCE is graded with the degree of store depletion and controlled locally in the subcellular microdomain where depletion occurs. SOCE provides distinct Ca2+ signals that selectively control specific endothelial functions: in calf pulmonary artery endothelial cells, the SOCE Ca2+ signal drives nitric oxide (an endothelium-derived relaxing factor of the vascular smooth muscle) production and controls activation and nuclear translocation of the transcription factor NFAT. Both cellular events are not affected by Ca2+ signals of comparable magnitude arising directly from Ca2+ release from intracellular stores, clearly indicating that SOCE regulates specific Ca2+-dependent cellular tasks by a unique and exclusive mechanism. This review discusses the mechanisms of intracellular Ca2+ regulation in vascular endothelial cells and the role of store-operated Ca2+ entry for endothelium-dependent smooth muscle relaxation and nitric oxide signaling, endothelial oxidative stress response, and excitation-transcription coupling in the vascular endothelium.
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Affiliation(s)
- Lothar A Blatter
- Department of Physiology and Biophysics, Rush University Medical Center, 1750 W. Harrison St., Chicago, IL, 60612, USA.
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6
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Plomaritas DR, Herbert LM, Yellowhair TR, Resta TC, Gonzalez Bosc LV, Walker BR, Jernigan NL. Chronic hypoxia limits H2O2-induced inhibition of ASIC1-dependent store-operated calcium entry in pulmonary arterial smooth muscle. Am J Physiol Lung Cell Mol Physiol 2014; 307:L419-30. [PMID: 24993130 DOI: 10.1152/ajplung.00095.2014] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Our laboratory shows that acid-sensing ion channel 1 (ASIC1) contributes to the development of hypoxic pulmonary hypertension by augmenting store-operated Ca(2+) entry (SOCE) that is associated with enhanced agonist-induced vasoconstriction and arterial remodeling. However, this enhanced Ca(2+) influx following chronic hypoxia (CH) is not dependent on an increased ASIC1 protein expression in pulmonary arterial smooth muscle cells (PASMC). It is well documented that hypoxic pulmonary hypertension is associated with changes in redox potential and reactive oxygen species homeostasis. ASIC1 is a redox-sensitive channel showing increased activity in response to reducing agents, representing an alternative mechanism of regulation. We hypothesize that the enhanced SOCE following CH results from removal of an inhibitory effect of hydrogen peroxide (H2O2) on ASIC1. We found that CH increased PASMC superoxide (O2 (·-)) and decreased rat pulmonary arterial H2O2 levels. This decrease in H2O2 is a result of decreased Cu/Zn superoxide dismutase expression and activity, as well as increased glutathione peroxidase (GPx) expression and activity following CH. Whereas H2O2 inhibited ASIC1-dependent SOCE in PASMC from control and CH animals, addition of catalase augmented ASIC1-mediated SOCE in PASMC from control rats but had no further effect in PASMC from CH rats. These data suggest that, under control conditions, H2O2 inhibits ASIC1-dependent SOCE. Furthermore, H2O2 levels are decreased following CH as a result of diminished dismutation of O2 (·-) and increased H2O2 catalysis through GPx-1, leading to augmented ASIC1-dependent SOCE.
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Affiliation(s)
- Danielle R Plomaritas
- Vascular Physiology Group, Department of Cell Biology and Physiology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico
| | - Lindsay M Herbert
- Vascular Physiology Group, Department of Cell Biology and Physiology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico
| | - Tracylyn R Yellowhair
- Vascular Physiology Group, Department of Cell Biology and Physiology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico
| | - Thomas C Resta
- Vascular Physiology Group, Department of Cell Biology and Physiology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico
| | - Laura V Gonzalez Bosc
- Vascular Physiology Group, Department of Cell Biology and Physiology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico
| | - Benjimen R Walker
- Vascular Physiology Group, Department of Cell Biology and Physiology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico
| | - Nikki L Jernigan
- Vascular Physiology Group, Department of Cell Biology and Physiology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico
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Sano E, Tashiro S, Tadakuma H, Takei T, Ueda T, Tsumoto K. Type 1 IFN inhibits the growth factor deprived apoptosis of cultured human aortic endothelial cells and protects the cells from chemically induced oxidative cytotoxicity. J Cell Biochem 2013; 113:3823-34. [PMID: 22821369 DOI: 10.1002/jcb.24259] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
It has been shown that the genesis of atherosclerotic lesions is resulted from the injury of vascular endothelial cells and the cell damage is triggered by oxygen radicals generated from various tissues. Human vascular endothelial cells can survive and proliferate depending on growth factors such as VEGF or basic FGF and are induced apoptosis by the deprivation of growth factor or serum. It was found that type 1 IFN inhibits the growth factor deprived cell death of human aortic endothelial cells (HAEC) and protects the cells from chemically induced oxidative cytotoxicity. The anti-apoptotic effects of type 1 IFN were certified by flow cytometry using annexin-V-FITC/PI double staining and cell cycle analysis, fluorescence microscopy using Hoechst33342 and PI, colorimetric assay for caspase-3 activity, p53 and bax mRNA expressions, and cell counts. It was considered that IFN-β inhibits the executive late stage apoptosis from the results of annexin-V-FITC/PI double staining and the inhibition of caspase-3 activity, and that the anti-apoptotic effect might be owing to the direct inhibition of the apoptotic pathway mediated by p53 from the transient down-regulation of bax mRNA expression. Whereas, type 1 IFN protected the cells from the oxidative cytotoxicity induced by tertiary butylhydroperoxide (TBH) under the presence of Ca(2+). The effects of IFN-β is more potent inhibitor of cell death than IFN-α. These results indicate that type 1 IFN, especially IFN-β may be useful for the diseases with vascular endothelium damage such as atherosclerosis or restenosis after angioplasty as a medical treatment or a prophylactic.
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Affiliation(s)
- Emiko Sano
- Department of Medical Proteomics Laboratory, Institute of Medical Science, The University of Tokyo, Shirokanedai, Tokyo, 108-8639, Japan.
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Adesanoye OA, Molehin OR, Delima AA, Adefegha AS, Farombi EO. Modulatory effect of methanolic extract ofVernonia amygdalina(MEVA) on tert-butyl hydroperoxide-induced erythrocyte haemolysis. Cell Biochem Funct 2012. [DOI: 10.1002/cbf.2933] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Omolola A. Adesanoye
- Drug Metabolism & Toxicology Research Laboratories, Department of Biochemistry, College of Medicine; University of Ibadan; Ibadan; Nigeria
| | - Olorunfemi R. Molehin
- Drug Metabolism & Toxicology Research Laboratories, Department of Biochemistry, College of Medicine; University of Ibadan; Ibadan; Nigeria
| | - Adetutu A. Delima
- Drug Metabolism & Toxicology Research Laboratories, Department of Biochemistry, College of Medicine; University of Ibadan; Ibadan; Nigeria
| | - Adeniyi S. Adefegha
- Drug Metabolism & Toxicology Research Laboratories, Department of Biochemistry, College of Medicine; University of Ibadan; Ibadan; Nigeria
| | - Ebenezer O. Farombi
- Drug Metabolism & Toxicology Research Laboratories, Department of Biochemistry, College of Medicine; University of Ibadan; Ibadan; Nigeria
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Abstract
The endothelium is a highly dynamic structure lining the inside of blood vessels that exhibits physical and chemical properties that are critical determinants of overall vascular function. Physically, the endothelium constitutes a semipermeable barrier. Chemically, the endothelium synthesizes numerous factors such as reactive oxygen species (ROS) that can act as autocrine and paracrine signaling molecules. Oxidative stress results when ROS levels increase to levels that cause cellular injury, and, in the endothelium oxidative stress leads to barrier disruption. Endothelial barrier disruption also results from increased cytosolic calcium through store-operated calcium (SOC) entry channels. Although it is known that ROS can interact with and regulate some ion channels, relatively little is known about the interaction of these species with components of endothelial SOC entry channels, the canonical transient receptor potential (TRPC) proteins. Here we review our current understanding of ROS-mediated TRPC channel function and how it affects SOC entry and endothelial barrier disruption.
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Affiliation(s)
- Donna L Cioffi
- Department of Biochemistry and Molecular Biology, Center for Lung Biology, University of South Alabama College of Medicine, Mobile, AL 36688, USA.
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10
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Pereira AC, Olivon VC, de Oliveira AM. Impaired calcium influx despite hyper-reactivity in contralateral carotid following balloon injury: eNOS involvement. Eur J Pharmacol 2010; 642:121-7. [DOI: 10.1016/j.ejphar.2010.05.051] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2009] [Revised: 03/25/2010] [Accepted: 05/06/2010] [Indexed: 11/24/2022]
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An Apparent Paradox: Attenuation of Phenylephrine-mediated Calcium Mobilization and Hyperreactivity to Phenylephrine in Contralateral Carotid After Balloon Injury. J Cardiovasc Pharmacol 2010; 56:162-70. [DOI: 10.1097/fjc.0b013e3181e571cd] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Steinert JR, Wyatt AW, Jacob R, Mann GE. Redox modulation of Ca2+ signaling in human endothelial and smooth muscle cells in pre-eclampsia. Antioxid Redox Signal 2009; 11:1149-63. [PMID: 19125611 DOI: 10.1089/ars.2008.2303] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Pre-eclampsia (PE) is a leading cause of maternal hypertension in pregnancy and is associated with fetal growth restriction, premature birth, and fetal and maternal mortality. Activation and dysfunction of the maternal and fetal endothelium in PE appears to be a consequence of increased oxidative stress, resulting from elevated levels of circulating lipid peroxides. Accumulating evidence implicates reactive oxygen species (ROS) in the pathogenesis of vascular dysfunction in PE, perhaps involving a disturbance in intracellular Ca(2+) signaling. Several ion-transport pathways are highly sensitive to oxidative stress, and the resulting modulation of ion transport by ROS will affect intracellular Ca(2+) homeostasis. We review the evidence that changes in ion transport induced by ROS may be linked with abnormalities in Ca(2+)-mediated signal transduction, leading to endothelial and smooth muscle dysfunction in maternal and fetal circulations in PE. As dysregulation of Ca(2+) signaling in fetal umbilical endothelial cells is maintained in culture and embryonic, fetal, and postnatal development is affected by the cellular redox state, we hypothesize that impaired redox signaling in PE may influence "programming" of the fetal cardiovascular system and endothelial function in adulthood.
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Affiliation(s)
- Joern R Steinert
- Cardiovascular Division, School of Medicine, King's College London, London, England
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13
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Florea SM, Blatter LA. The effect of oxidative stress on Ca2+ release and capacitative Ca2+ entry in vascular endothelial cells. Cell Calcium 2007; 43:405-15. [PMID: 17767954 DOI: 10.1016/j.ceca.2007.07.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2007] [Revised: 06/19/2007] [Accepted: 07/15/2007] [Indexed: 01/24/2023]
Abstract
Oxidative stress imposed by the accumulation of oxygen free radicals (reactive oxygen species, ROS) has profound effects on Ca2+ homeostasis in the vascular endothelium, leading to endothelial dysfunctions and the development of cardiovascular pathologies. We tested the effect of the oxidant and ROS generator tert-butyl-hydroperoxide (tBuOOH) on Ca2+ signaling in single cultured calf pulmonary artery endothelial (CPAE) cells loaded with the fluorescent Ca2+ indicator indo-1. Acute brief (5 min) exposures to tBuOOH had no effect on basal cytosolic free Ca2+ ([Ca2+](i)), agonist (ATP)-induced Ca2+ release from the endoplasmic reticulum (ER) and on Ca(2+) store depletion-dependent capacitative Ca2+ entry (CCE). Prolonged (60 min) exposure to tBuOOH did not affect intracellular Ca2+ release, but caused a profound inhibition of CCE. After 120 min of treatment with tBuOOH not only was CCE further reduced, but also ATP-induced Ca2+ release due to a slow depletion of the stores that resulted from CCE inhibition. The antioxidant Trolox (synthetic vitamin E analog) prevented the inhibition of CCE by tBuOOH and attenuated the increase of [ROS](i), indicating that inhibition of CCE was due to the oxidant effects of tBuOOH. The data suggest that in vascular endothelial cells oxidative stress primarily affects Ca2+ influx in response to Ca2+ loss from internal stores. [Ca2+](i) is an important signal for the production and release of endothelium-derived factors such as nitric oxide (NO). Since CCE is the preferential Ca2+ source for NO synthase activation, the finding that oxidative stress inhibits CCE may explain how oxidative stress contributes to endothelial dysfunction-related cardiovascular pathologies.
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Affiliation(s)
- Stela M Florea
- Department of Physiology, Loyola University Chicago, 2160 S. First Avenue, Maywood, IL 60153, USA
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Brzezinska AK, Lohr N, Chilian WM. Electrophysiological effects of O2*- on the plasma membrane in vascular endothelial cells. Am J Physiol Heart Circ Physiol 2005; 289:H2379-86. [PMID: 15964927 DOI: 10.1152/ajpheart.00132.2005] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Vascular dysfunction is a hallmark of many diseases, including coronary heart disease, stroke, and diabetes. The underlying mechanisms of these disorders are intimately associated with an increase in oxidative stress and excess generation of reactive oxygen species. Here, we report that the anionic free radical, superoxide (O2*- ), directly affects the function of ion channels in vascular endothelial cells. Vascular endothelial cells were exposed to O2*- under physiological, symmetrical chloride and chloride-free conditions. Superoxide was generated from the reaction of xanthine (0.2 mM) and xanthine oxidase (0.1, 1, and 10 mU/ml) while its effects were determined with the whole cell mode of the patch-clamp technique. Inhibitors of K+ and Cl- channels were used to determine the role of these ion channels in mediating the electrophysiological effects of superoxide. The addition of O2*- caused a dose-dependent depolarization of endothelial cells and activation of the whole cell current. Activation of superoxide-dependent current was observed in the presence of inhibitors of K+ channels, Ba2+ (100 microM) or iberiotoxin (100 nM), and was not affected by inhibitors of nonselective cation channels, La3+, or by inhibition of the Cl-/HCO3- transporter by bumetanide. The inhibitors of the Cl- channel, NPPB (0.1 mM) or DIDS (100 microM), partially prevented activation of superoxide-dependent current but were unable to reverse it. The effects of superoxide on the amplitude of whole cell current were prevented and reversed by superoxide dismutase. Taken together, these results suggest that superoxide directly affects the function of ion channels in vascular endothelium but the mechanisms of its modulatory effects remain unresolved.
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Affiliation(s)
- Anna K Brzezinska
- Dept. of Physiology, LSU Health Sciences Center, 1901 Perdido St., New Orleans, LA 70112, USA.
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Schaeffer G, Levak-Frank S, Spitaler MM, Fleischhacker E, Esenabhalu VE, Wagner AH, Hecker M, Graier WF. Intercellular signalling within vascular cells under high D-glucose involves free radical-triggered tyrosine kinase activation. Diabetologia 2003; 46:773-83. [PMID: 12811469 DOI: 10.1007/s00125-003-1091-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2002] [Revised: 01/14/2003] [Indexed: 11/27/2022]
Abstract
AIMS/HYPOTHESIS Diabetes mellitus is associated with endothelial dysfunction in human arteries due to the release of superoxide anions (*O(2)(-)) that was found to occur predominantly in smooth muscle cells (SMC). This study was designed to elucidate the impact of high glucose concentration mediated radical production in SMC on EC. Pre-treatment of vascular SMC with increased D-glucose enhanced release of *O(2)(-). METHODS Microscope-based analyses of intracellular free Ca(2+) concentration (fura-2), immunohistochemistry (f-actin) and tyrosine kinase activity were performed. Furthermore, RT-PCR and Western blots were carried out. RESULTS Interaction of EC with SMC pre-exposed to high glucose concentration yielded changes in endothelial Ca(2+) signalling and polymerization of f-actin in a concentration-dependent and superoxide dismutase (SOD) sensitive manner. This interaction activated endothelial tyrosine kinase(s) but not NFkappaB and AP-1, while SOD prevented tyrosine kinase stimulation but facilitated NFkappaB and AP-1 activation. Erbstatin, herbimycin A and the src family specific kinase inhibitor PP-1 but not the protein kinase C inhibitor GF109203X prevented changes in endothelial Ca(2+) signalling and cytoskeleton organization induced by pre-exposure of SMC to high glucose concentration. Adenovirus-mediated expression of kinase-inactive c-src blunted the effect of pre-exposure of SMC to high glucose concentration on EC. CONCLUSIONS/INTERPRETATION These data suggest that SMC-derived *O(2)(-) alter endothelial cytoskeleton organization and Ca(2+) signalling via activation of c-src. The activation of c-src by SMC-derived radicals is a new concept of the mechanisms underlying vascular dysfunction in diabetes.
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Affiliation(s)
- G Schaeffer
- Department of Medical Biochemistry and Medical Molecular Biology, University of Graz, Harrachgasse 21/III, 8010 Graz, Austria
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16
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Abstract
Reactive oxygen and nitrogen species can be used as a messengers in normal cell functions. However, at oxidative stress levels they can disrupt normal physiological pathways and cause cell death. Such a switch is largely mediated through Ca(2+) signaling. Oxidative stress causes Ca(2+) influx into the cytoplasm from the extracellular environment and from the endoplasmic reticulum or sarcoplasmic reticulum (ER/SR) through the cell membrane and the ER/SR channels, respectively. Rising Ca(2+) concentration in the cytoplasm causes Ca(2+) influx into mitochondria and nuclei. In mitochondria Ca(2+) accelerates and disrupts normal metabolism leading to cell death. In nuclei Ca(2+) modulates gene transcription and nucleases that control cell apoptosis. Both in nuclei and cytoplasm Ca(2+) can regulate phosphorylation/dephosphorylation of proteins and can modulate signal transduction pathways as a result. Since oxidative stress is associated with many diseases and the aging process, understanding how oxidants alter Ca(2+) signaling can help to understand process of aging and disease, and may lead to new strategies for their prevention.
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Affiliation(s)
- Gennady Ermak
- Ethel Percy Andrus Gerontology Center, and Division of Molecular Biology, University of Southern California, Rm 306, 3715 McClintock Avenue, Los Angeles, CA 90089-0191, USA
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17
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Pogan L, Garneau L, Bissonnette P, Wu L, Sauvé R. Abnormal Ca2+ signalling in vascular endothelial cells from spontaneously hypertensive rats: role of free radicals. J Hypertens 2001; 19:721-30. [PMID: 11330875 DOI: 10.1097/00004872-200104000-00009] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE To test the hypothesis that the Ca2+ signal transduction process in endothelial cells from genetically hypertensive rats (SHR) is affected by an overproduction of free radicals. METHODS The Ca2+ response to the inositol 1,4,5-triphosphate (IP3) mobilizing agonist, ATP, was measured using the fluorescent probe, fura-2, in endothelial cells from Sprague-Dawley rats, and in young and age-matched genetically hypertensive rats (SHR). The effect of free radicals and reducing agents on the intracellular release of Ca2+ and IP3productionwas determined in resting and ATP-stimulated cells. Experiments were also performed to compare the level of expression and enzymatic activity of catalase and superoxide dismutase (SOD) in endothelial cells from SHR and Sprague-Dawley rats. RESULTS The exposure of aortic endothelial cells from Sprague-Dawley rats to the free-radical generating system, hypoxanthine + xanthine oxidase (HX/XO), caused a time- and concentration-dependent inhibition of the ATP-induced Ca2+ response. A similar HX/XO-dependent inhibition was also observed in Sprague-Dawley cells stimulated with the endoplasmic reticulum Ca2+-ATPase inhibitor, thapsigargin. Incubation with the antioxidative enzymes, catalase and SOD, had no effect on the ATP-induced Ca2+ release in Sprague-Dawley cells, but led to a strong increase in the internal release of Ca2+ in cells from adult (12 weeks old) or young (3 weeks old) SHR. The effect of antioxidants was not related either to an enhancement of the ATP-induced production of IP3, or to a lower expression and activity of SOD and catalase. CONCLUSION The present work provides evidence that the Ca2+ signalling process in SHR endothelial cells is affected by an overproduction of free radicals, resulting in a depletion of releasable Ca2+ from IP3-sensitive and insensitive Ca2+ pools. These results point towards a beneficial action of antioxidants on Ca2+ signalling in endothelial cells from models of hypertension.
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Affiliation(s)
- L Pogan
- Département de Physiologie, Faculté de Médecine, Université de Montréal, Québec, Canada
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18
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Abstract
Recent evidence suggests that oxidant stress plays a major role in several aspects of vascular biology. Oxygen free radicals are implicated as important factors in signaling mechanisms leading to vascular pathologies such as postischemic reperfusion injury and atherosclerosis. The role of intracellular Ca(2+) in these signaling events is an emerging area of vascular research that is providing insights into the mechanisms mediating these complex physiological processes. This review explores sources of free radicals in the vasculature, as well as effects of free radicals on Ca(2+) signaling in vascular endothelial and smooth muscle cells. In the endothelium, superoxides enhance and peroxides attenuate agonist-stimulated Ca(2+) responses, suggesting differential signaling mechanisms depending on radical species. In smooth muscle cells, both superoxides and peroxides disrupt the sarcoplasmic reticulum Ca(2+)-ATPase, leading to both short- and long-term effects on smooth muscle Ca(2+) handling. Because vascular Ca(2+) signaling is altered by oxidant stress in ischemia-related disease states, understanding these pathways may lead to new strategies for preventing or treating arterial disease.
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Affiliation(s)
- K M Lounsbury
- Department of Pharmacology, University of Vermont School of Medicine, Burlington, VT 05405, USA.
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19
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Graier WF, Posch K, Fleischhacker E, Wascher TC, Kostner GM. Increased superoxide anion formation in endothelial cells during hyperglycemia: an adaptive response or initial step of vascular dysfunction? Diabetes Res Clin Pract 1999; 45:153-60. [PMID: 10588368 DOI: 10.1016/s0168-8227(99)00045-5] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
In diabetes mellitus, the risk for cardiovascular complications and development of atherosclerosis is increased compared with healthy individuals. Recently evidence was provided that increased production of superoxide anions occurs in endothelial cells during hyperglycemia. In order to evaluate the potential impact of the enhanced formation of this oxygen radical for vascular cell dysfunction and its role in tissue adaptation, it is essential to assess the effect of superoxide anions on endothelial cell function. Here, we present new data and review our previous work on the effects of superoxide anions on endothelial vascular function, such as intracellular Ca2+ signal cascade, formation and bioactivity of nitric oxide. Based on the presented data we discuss superoxide anion production as a two faced phenomenon. In lower concentrations, superoxide anions are mediators of an endothelium adaptation to ensure endothelial vasomotion control. However, in higher concentrations superoxide anions disrupt endothelial-smooth muscle crosstalk resulting in vessel wall dysfunction and vascular wall dysfunction.
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MESH Headings
- Adaptation, Physiological
- Animals
- Aorta
- Arteries
- Calcium/metabolism
- Cells, Cultured
- Diabetic Angiopathies/etiology
- Diabetic Angiopathies/physiopathology
- Endothelium, Vascular/cytology
- Endothelium, Vascular/metabolism
- Endothelium, Vascular/physiology
- Female
- Glucose/pharmacology
- Hyperglycemia/metabolism
- Models, Cardiovascular
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Muscle, Smooth, Vascular/physiology
- Nitric Oxide/metabolism
- Signal Transduction
- Superoxides/metabolism
- Swine
- Uterus/blood supply
- Xanthine/pharmacology
- Xanthine Oxidase/pharmacology
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Affiliation(s)
- W F Graier
- Department of Medical Biochemistry, University of Graz, Austria.
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20
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Grover AK, Samson SE, Misquitta CM, Elmoselhi AB. Effects of peroxide on contractility of coronary artery rings of different sizes. Mol Cell Biochem 1999; 194:159-64. [PMID: 10391135 DOI: 10.1023/a:1006902603056] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Reactive oxygen species (ROS, free radicals) produced during cardiac ischemia and reperfusion can damage the contractile functions of arteries. The sarcoplasmic reticulum (SR) Ca2+ pump in coronary artery smooth muscle is very sensitive to ROS. Here we show that contractions of de-endothelialized rings from porcine left coronary artery produced by the hormone Angiotensin II and by the SR Ca2+ pump inhibitors cyclopiazonic acid and thapsigargin correlate negatively with the tissue weight. In contrast, the contractions due to membrane depolarization by high KCl correlate positively. Peroxide also produces a small contraction which correlates negatively with the tissue weight. When artery rings are treated with peroxide and washed, their ability to contract with Angiotensin II, cyclopiazonic acid and thapsigargin decreases. Thus, the SR Ca2+ pump may play a more important role in the contractility of the smaller segments of the coronary artery than in the larger segments. These results are consistent with the hypothesis that ROS which damage the SR Ca2+ pump affect the contractile function of the distal segments more adversely than of the proximal segments.
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Affiliation(s)
- A K Grover
- Department of Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
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21
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Sandhu V, Miller M, Grover AK. Effects of peroxide on the fluorescence of the Ca2+ probe Fluo 3 and the pH probe BCECF. Mol Cell Biochem 1998; 178:77-80. [PMID: 9546584 DOI: 10.1023/a:1006867423362] [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: 02/07/2023]
Abstract
Fluorescence probes are invaluable tools in monitoring intracellular ion concentrations. They have also been used for studying how reactive oxygen species alter these concentrations and yet there are no studies indicating how reactive oxygen species directly affect the characteristics of the probes. Our concern was that if reactive oxygen were to affect characteristics of these probes, these measurements would be inconsequential. Therefore, we examined the effects of peroxide on the Ca2+-sensitive dye Fluo 3 and the pH sensitive dye BCECF. Peroxide concentrations below 10 mM did not alter fluorescence or binding characteristics of either dye. Since the concentrations of peroxide used in most pathophysiological experiments are in the micromolar range, we conclude that these probes are appropriate for monitoring the effects of peroxide on intracellular ion concentrations.
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Affiliation(s)
- V Sandhu
- Department of Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
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22
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Grover AK, Samson SE. Peroxide resistance of ER Ca2+ pump in endothelium: implications to coronary artery function. THE AMERICAN JOURNAL OF PHYSIOLOGY 1997; 273:C1250-8. [PMID: 9357769 DOI: 10.1152/ajpcell.1997.273.4.c1250] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We examined the effects of peroxide on the sarco(endo)plasmic reticulum Ca2+ (SERCA) pump in pig coronary artery endothelium and smooth muscle at three organizational levels: Ca2+ transport in permeabilized cells, cytosolic Ca2+ concentration in intact cells, and contractile function of artery rings. We monitored the ATP-dependent, azide-insensitive, oxalate-stimulated 45Ca2+ uptake by saponin-permeabilized cultured cells. Low concentrations of peroxide inhibited the uptake less effectively in endothelium than in smooth muscle whether we added the peroxide directly to the Ca2+ uptake solution or treated intact cells with peroxide and washed them before the permeabilization. An acylphosphate formation assay confirmed the greater resistance of the SERCA pump in endothelial cells than in smooth muscle cells. Pretreating smooth muscle cells with 300 microM peroxide inhibited (by 77 +/- 2%) the cyclopiazonic acid (CPA)-induced increase in cytosolic Ca2+ concentration in a Ca2+-free solution, but it did not affect the endothelial cells. Peroxide pretreatment inhibited the CPA-induced contraction in deendothelialized arteries with a 50% inhibitory concentration of 97 +/- 13 microM, but up to 500 microM peroxide did not affect the endothelium-dependent, CPA-induced relaxation. Similarly, 500 microM peroxide inhibited the angiotensin-induced contractions in deendothelialized arteries by 93 +/- 2%, but it inhibited the bradykinin-induced, endothelium-dependent relaxation by only 40 +/- 13%. The greater resistance of the endothelium to reactive oxygen may be important during ischemia-reperfusion or in the postinfection immune response.
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Affiliation(s)
- A K Grover
- Department of Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
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23
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Volk T, Hensel M, Kox WJ. Transient Ca2+ changes in endothelial cells induced by low doses of reactive oxygen species: role of hydrogen peroxide. Mol Cell Biochem 1997; 171:11-21. [PMID: 9201690 DOI: 10.1023/a:1006886215193] [Citation(s) in RCA: 75] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Cultured human and rat endothelial cells were used to study cellular toxicity and Ca2+ signalling upon exposure to reactive oxygen species. Superoxide and hydrogen peroxide (O2.-/H2O2) were produced by the hypoxanthine/xanthine oxidase system (HX/XO) and caused intracellular Ca2+ concentration ([Ca2+]i) to rise steadily when activities above 2 mU/ml were used. These Ca2+ increases were also measured when the glucose/glucose oxidase (G/GO) system above 5 mU/ml was used to produce hydrogen peroxide (H2O2). Gross morphological changes appeared to parallel elevated [Ca2+]i levels preceding cell death. However, when HX/XO or G/GO were used at non toxic doses rapid and transient changes in [Ca2+]i were measured. These treatments did not alter subsequent receptor mediated Ca2+ signalling induced by ATP (10 microM) or histamine (100 microM). Superoxide dismutase (50 U/ml), which dismutates O2.- into H2O2 also had no influence, whereas catalase (50 U/ml), which removes H2O2, completely diminished transient [Ca2+]i responses. H2O2 added directly was able to induce similar Ca2+ transients when concentrations of at least 500 microM were used. Buffering trace amounts of iron (o-phenanthroline; 200 microM) in order to inhibit .OH radical formation was not effective to alter Ca2+ changes. Experiments performed in Ca(2+)-free buffer showed a similar rise in [Ca2+]i and readdition of Ca2+ to the extracellular medium indicated the activation of store operated Ca2+ entry. Blocking Ca(2+)-ATPases of the endoplasmatic reticulum with thapsigargin (1 microM) inhibited ROS induced transient increases and cells preincubated with pertussis toxin (200 nM) showed unchanged Ca2+ transients after exposure to both enzyme systems. Phospholipase C inhibitor U73122 (2 microM) effectively reduced hydrogen peroxide induced emptying of intracellular stores. Taken together, we demonstrate that enzymatically produced non-toxic H2O2 rather than O2.- or .OH causes calcium signalling from thapsigargin sensitive stores, and activates store operated Ca2+ entry at least partially by activating phospholipase C. These changes clearly differ from pathological 'oxidative stress' associated with a progressive increase in [Ca2+]i.
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Affiliation(s)
- T Volk
- Department of Anaesthesiology and Intensive Care, University Hospital Charité, Berlin, Germany
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24
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Choi J, Liu RM, Forman HJ. Adaptation to oxidative stress: quinone-mediated protection of signaling in rat lung epithelial L2 cells. Biochem Pharmacol 1997; 53:987-93. [PMID: 9174112 DOI: 10.1016/s0006-2952(96)00867-2] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Cells can respond to a sublethal oxidative stress by up-regulating their intracellular glutathione (GSH) pool. Such increased GSH concentration is likely to be protective against further oxidative challenge, and, in fact, pre-exposure to low levels of oxidants confers increased cellular resistance to subsequent greater oxidative stress. Previously, we have shown that pretreatment of rat lung epithelial L2 cells with sublethal concentrations of tert-butylhydroquinone (TBHQ) increases intracellular GSH concentration in a concentration- and time-dependent manner. This increase resulted from up-regulation of both gamma-glutamyltranspeptidase (GGT) and gamma-glutamylcysteine synthetase (GCS). Therefore, we investigated whether such increased GSH concentration protected these cells against a subtle loss in function caused by a subsequent challenge with sublethal concentrations of tert-butyl hydroperoxide (tBOOH) (< or = 200 microM), mimicking a physiological oxidative stress. Activation of L2 cell purinoreceptors with 100 microM ADP caused an elevation of intracellular Ca2+. This response was suppressed by a brief pre-exposure to tBOOH. The inhibition, however, was alleviated dramatically by a 16-hr pretreatment with 50 microM TBHQ. The same TBHQ pretreatment also protected the cells from ATP-depletion induced by tBOOH. L-Buthionine S,R-sulfoximine (BSO), an irreversible inhibitor of GCS, prevented the increase in intracellular GSH and also completely removed the protection by TBHQ in maintaining the ATP level. Thus, pre-exposure to a sublethal level of TBHQ results in protection of cell functions from hydroperoxide toxicity. This protection appears to depend on alteration of the intracellular GSH pool, the modulation of which constitutes an adaptive response to oxidative stress.
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Affiliation(s)
- J Choi
- Department of Molecular Pharmacology and Toxicology, University of Southern California, School of Pharmacy, Los Angeles 90033, U.S.A
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25
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Broche VF, Suàrez AR, Olembe E, Fernàndez GE, Céspedes EM, Garcia JC, Reynoso E, Nùñez P, Prieto E. Aprotinin effects related to oxidative stress in cardiosurgery with mechanical cardiorespiratory support (CMCS). Ann N Y Acad Sci 1996; 793:521-4. [PMID: 8906205 DOI: 10.1111/j.1749-6632.1996.tb33555.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
There is evidence to support a relationship between oxidative stress and protease release in "ischemia-reperfusion damage." We have proposed that aprotinin may exert an antioxidant effect. A double blind clinical trial was performed with a control (G-1) and treated (G-2) groups, both submitted to CMCS. Blood samples were taken 5 times. Biochemical indicators were measured spectrophotometrically. Aprotinin was supplied by Bayer. Malonildialdehyde levels were greater in G-1 (7.2 +/- 3.6 nmoles/ml) than in G-2 (4 +/- 1.65) at the time of reperfusion. Phospholipase A2 exhibited a tendency of higher activity in G-1 than in G-2. Uric acid levels were higher in G-2 (431 +/- 274 mumoles/1) than in G-1 (224 +/- 188) at 5 minutes after aortic clamping, and catalase activity was greater in G-2 (294 +/- 55 KU/1) than in G-1 (118 +/- 47) at time of reperfusion. Low cardiac output was 10% in G-2 and 30% in G-1. Arrythmias appeared in 30% of G-2 and in 60% of G-1. These results suggest an antioxidant effect of aprotinin under ischemia-reperfusion conditions.
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Affiliation(s)
- V F Broche
- Biomedical Research Center Victoria de Giròn, Havana, Cuba.
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26
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Koliwad SK, Elliott SJ, Kunze DL. Oxidized glutathione mediates cation channel activation in calf vascular endothelial cells during oxidant stress. J Physiol 1996; 495 ( Pt 1):37-49. [PMID: 8866350 PMCID: PMC1160723 DOI: 10.1113/jphysiol.1996.sp021572] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
1. The oxidant, tert-butylhydroperoxide (tBuOOH) depolarizes calf pulmonary artery endothelial cells by activating a non-selective cation channel. To identify the molecular mediator of channel activation during oxidant stress, the patch-clamp technique was used to compare tBuOOH-induced changes in membrane potential and channel activity with those induced by oxidized glutathione (GSSG), a cytosolic product of oxidant metabolism. 2. When recording pipettes contained GSSG (2 mM), whole-cell zero-current potential measured immediately following pipette break-in was not different from control values (-57 mV). However, within 20 min of break-in, zero-current potential was depolarized to -7 mV. The time course of depolarization was dependent on the concentration of GSSG and was accelerated by inhibition of GSSG metabolism. 3. In excised membrane patches, channels were activated by internal GSSG, but not by internal tBuOOH, reduced glutathione (GSH), or external GSSG. Channels were equal in size (28 pS) and in ionic selectivity to those activated by incubation of intact cells with tBuOOH. As little as 20 microM GSSG was sufficient to maximally activate channels. However, the time course of channel activation was concentration dependent between 20 microM and 2 mM GSSG. 4. Channel activation by GSSG was reversed by GSH and by increasing the [GSH]:[GSSG] ratio. Likewise, channel activation by pre-incubation of intact cells with tBuOOH was reversed by GSH applied after patch excision. 5. These results strongly suggest that GSSG is an endogenous intracellular mediator of channel activation and depolarization during oxidant stress.
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Affiliation(s)
- S K Koliwad
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA. S.K.Koliwad:
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27
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Koliwad SK, Kunze DL, Elliott SJ. Oxidant stress activates a non-selective cation channel responsible for membrane depolarization in calf vascular endothelial cells. J Physiol 1996; 491 ( Pt 1):1-12. [PMID: 9011602 PMCID: PMC1158754 DOI: 10.1113/jphysiol.1996.sp021191] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
1. In vascular endothelial cells, oxidant stress increases cell Na+ content and inhibits the agonist-stimulated influx of external Ca2+. Further, oxidant stress increases uptake of Ca2+ into otherwise quiescent endothelial cells. To determine the mechanism responsible for altered Na+ and Ca2+ homeostasis, the present study examined the effect of oxidant stress on ionic current and channel activity in calf pulmonary artery endothelial cells. 2. Voltage-clamped control cells had a zero-current potential of -60 mV. Incubation of cells with the oxidant tert-butylhydroperoxide (tBuOOH; 0.4 mM, 1 h) caused depolarization to -4 mV and activation of ionic current equally selective for Na+ and K+. 3. Cell-attached membrane patches made on tBuOOH-treated cells contained ion channels that had a bidirectional conductance of 30 pS and that were not present in patches from control cells. Inside-out patches excised from oxidant-treated cells showed the channel to be equally selective for Na+ and K+ and to allow inward Ca2+ current. 4. Oxidant-activated channels were observed to display two gating modalities that were further evident during analysis of single-channel open probability. Neither modality was significantly affected by altering internal [Ca2+] (1 microM-10 nM). 5. Activation of non-selective channels provides a possible mechanism by which oxidants may increase endothelial cell Na+ content. Channel permeability to Ca2+ may account in part for the elevation of cytosolic free [Ca2+] that occurs in oxidant-treated cells. 6. Channel activation is associated with membrane depolarization, a mechanism that may contribute to oxidant inhibition of the agonist-stimulated Ca2+ influx pathway.
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Affiliation(s)
- S K Koliwad
- Department of Molecular Physiology, Baylor College of Medicine, Houston, TX 77030, USA
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28
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Henschke PN, Elliott SJ. Oxidized glutathione decreases luminal Ca2+ content of the endothelial cell ins(1,4,5)P3-sensitive Ca2+ store. Biochem J 1995; 312 ( Pt 2):485-9. [PMID: 8526860 PMCID: PMC1136288 DOI: 10.1042/bj3120485] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The model oxidant, t-butyl hydroperoxide (t-buOOH), inhibits Ins(1,4,5)P3-dependent Ca2+ signalling in calf pulmonary artery endothelial cells. Metabolism of t-buOOH within the cytosol is coupled to the oxidation of glutathione. In this study, we investigated whether oxidized glutathione (GSSG) is the intracellular moiety responsible for mediating the effects of t-buOOH on Ca2+ signalling. The increase in cytosolic [Ca2+] stimulated by application of 2,5-di-t-butylhydroquinone (BHQ) was used to estimate the luminal Ca2+ content of the Ins(1,4,5)P3-sensitive store in intact cells. Luminal Ca2+ content was unaffected by t-buOOH (0.4 mM, 0-3 h) unless intracellular GSSG content was concomitantly elevated. The effect was specific for increased GSSG and was not replicated by depletion of GSH. These results suggest that cytosolic GSSG, produced endogenously within the endothelial cell, decreases the luminal Ca2+ content of Ins(1,4,5)P3-sensitive Ca2+ stores. Depletion of internal Ca2+ stores by GSSG may represent a key mechanism by which some forms of oxidant stress inhibit signal transduction in vascular tissue. At the plasma membrane, t-buOOH is known to inhibit the capacitative Ca2+ influx pathway. Increased intracellular GSSG potentiated the inhibitory effect of t-buOOH on Ca2+ influx, thereby providing the first evidence that activity of the capacitative Ca2+ influx channel is sensitive to thiol reagents formed endogenously within the cell.
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Affiliation(s)
- P N Henschke
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas 77030, USA
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29
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Abstract
The endothelium modulates vascular tone, vasoreactivity, and permeability in response to agonist-stimulation. Much of the pathophysiology of oxidant-induced vascular injury can be attributed to endothelial cell dysfunction. In the past several years, the effects of oxidant stress on agonist-stimulated Ca(2+)-channels have been described. More recently, the effects of oxidant stress on several other endothelial membrane-transport systems have been elucidated. It now appears that inhibition of the agonist-stimulated Ca2+ channel is due at least in part to membrane depolarization via oxidant-activation of a Na(+)-permeable, nonselective cation channel. In this review, the effects of oxidant stress on ion transport through the agonist-stimulated Ca2+ influx channel, Na+ and K+ channels, Na+/K(+)-ATPase, Ca(2+)-ATPase, and the Na+/K+/2Cl- cotransporter are discussed. The interrelated effects of oxidant stress on these endothelial membrane transport pathways are considered, and the net effect on Ca2+ signaling is described.
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Affiliation(s)
- S J Elliott
- Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
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30
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Clementi E, Martini A, Stefani G, Meldolesi J, Volpe P. LU52396, an inhibitor of the store-dependent (capacitative) Ca2+ influx. Eur J Pharmacol 1995; 289:23-31. [PMID: 7781709 DOI: 10.1016/0922-4106(95)90164-7] [Citation(s) in RCA: 18] [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
The effects of 1-[2-(4-fluorophenyl)cyclohexyl]-2-[4-(3-phenylalkyl)-piperazin -1-yl]- ethanol, LU52396, on a) Ca2+ influx across the plasma membrane and b) Ca2+ mobilization from intracellular rapidly-exchanging Ca2+ stores were investigated in HeLa cells and in isolated microsomal fractions derived from the cerebellum and the skeletal muscle. LU52396 was found to be a potent inhibitor (Ki of about 2 microM) of the Ca2+ influx activated by depletion of intracellular Ca2+ stores, a phenomenon referred to as store-dependent or capacitative Ca2+ influx. Such an effect, which was reversed by cell washing, was mediated neither by a depolarization of the cell, with decrease in the driving force for cation influx, nor by a change of the intracellular pH, and might therefore be due to a direct action of the drug on either the responsible channel in the plasma membrane or, less likely, on its regulatory mechanisms. Additional effects, i.e. inhibition of receptor-mediated Ca2+ influx, of Ca2+ release from intracellular stores via either inositol 1,4,5-trisphosphate or ryanodine receptors, and of Ca2+ reuptake into the stores via sarcoplasmic-endoplasmic reticulum Ca(2+)-ATPases, were also induced by the drug, however at concentrations 20-fold or more than those effective on the store-dependent influx. To our knowledge LU52396 is the first pharmacological tool that is found to be addressed with some preference to the store-dependent Ca2+ influx. It promises, therefore, to be useful for the characterization of the process, the identification of the responsible channel and, possibly, also of the molecular mechanisms through which these channels operate.
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Affiliation(s)
- E Clementi
- Chair of Pharmacology, Faculty of Pharmacy, University of Reggio Calabria, Catanzaro, Italy
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31
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Dreher D, Junod AF. Differential effects of superoxide, hydrogen peroxide, and hydroxyl radical on intracellular calcium in human endothelial cells. J Cell Physiol 1995; 162:147-53. [PMID: 7814447 DOI: 10.1002/jcp.1041620118] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Changes in intracellular Ca2+ homeostasis are thought to contribute to cell dysfunction in oxidative stress. The hypoxanthine-xanthine oxidase system (X-XO) mobilizes Ca2+ from intracellular stores and induces a marked rise in cytosolic calcium in different cell types. To identify the reactive O2 species involved in the disruption of calcium homeostasis by X-XO, we studied the effect of X-XO on [Ca2+]i by spectrofluorimetry with fura-2 in human umbilical vein endothelial cells (HUVEC). The [Ca2+]i response to X-XO was essentially diminished by superoxide dismutase (SOD) (200 U/ml) and catalase (CAT) (200 U/ml), which scavenge the superoxide anion, O2-, or H2O2, respectively. The [Ca2+]i increase stimulated by 10 nmol H2O2/ml/min, generated from the glucose-glucose oxidase system, or 10 microM H2O2, given as bolus, was about a third of that induced by X-XO (10 nmol O2-/ml/min) but was comparable to that induced by X-XO in the presence of SOD. The X-XO-stimulated [Ca2+]i increase was significantly reduced by 100 microM o-phenanthroline, which inhibits the iron-catalysed formation of the hydroxyl radical. On the other hand, the [Ca2+]i response to low dose X-XO (1 nmol O2-/ml/min) was markedly enhanced in the presence of 1 microM H2O2, which itself had no effect on [Ca2+]i. More than 50% of this synergistic effect was prevented by o-phenanthroline. These results indicate that the effect of X-XO on calcium homeostasis appears to result from an interaction of O2- and H2O2, which could be explained by the formation of the hydroxyl radical.
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Affiliation(s)
- D Dreher
- Respiratory Division, Hôpital Cantonal Universitaire de Genève, Switzerland
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32
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O'Donnell V, Burkitt MJ. Mitochondrial metabolism of a hydroperoxide to free radicals in human endothelial cells: an electron spin resonance spin-trapping investigation. Biochem J 1994; 304 ( Pt 3):707-13. [PMID: 7818471 PMCID: PMC1137392 DOI: 10.1042/bj3040707] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Oxidative damage to the vascular endothelium may be an important event in the promotion of atherosclerosis. Several lines of evidence suggest that lipid hydroperoxides may be responsible for the induction of such damage. Hydroperoxides cause loss of endothelial cell integrity, increase the permeability of the endothelium to macromolecules, and compromise its ability to control vascular tone via the secretion of vasoactive molecules in response to receptor stimulation. The molecular mechanisms responsible for these effects are, however, poorly understood. In this paper, we describe an e.s.r. spin-trapping investigation into the metabolism of the model hydroperoxide compound tert-butylhydroperoxide to reactive free radicals in intact human endothelial cells. The hydroperoxide is shown to undergo a single electron reduction to form free radicals. Experiments with metabolic poisons indicate that the mitochondrial electron-transport chain is the source of electrons for this reduction. The metal-ion-chelating agent desferrioxamine was found to prevent cell killing by tert-butylhydroperoxide, but did not affect free radical formation, suggesting that free metal ions may serve to promote free-radical chain reactions involved in cell killing following the initial conversion of the hydroperoxide to free radicals by mitochondria. These processes may well be responsible for many of the reported effects of hydroperoxides on endothelial cell integrity and function.
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Affiliation(s)
- V O'Donnell
- Division of Biochemical Sciences, Rowett Research Institute, Bucksburn, Aberdeen, U.K
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