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Reiniers MJ, de Haan LR, Reeskamp LF, Broekgaarden M, Hoekstra R, van Golen RF, Heger M. Optimal Use of 2',7'-Dichlorofluorescein Diacetate in Cultured Hepatocytes. Methods Mol Biol 2022; 2451:721-747. [PMID: 35505044 DOI: 10.1007/978-1-0716-2099-1_39] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Oxidative stress is a state that arises when the production of reactive transients overwhelms the cell's capacity to neutralize the oxidants and radicals. This state often coincides with the pathogenesis and perpetuation of numerous chronic diseases. On the other hand, medical interventions such as radiation therapy and photodynamic therapy generate radicals to selectively damage and kill diseased tissue. As a result, the qualification and quantification of oxidative stress are of great interest to those studying disease mechanisms as well as therapeutic interventions. 2',7'-Dichlorodihydrofluorescein-diacetate (DCFH2-DA) is one of the most widely used fluorogenic probes for the detection of reactive transients. The nonfluorescent DCFH2-DA crosses the plasma membrane and is deacetylated by cytosolic esterases to 2',7'-dichlorodihydrofluorescein (DCFH2). The nonfluorescent DCFH2 is subsequently oxidized by reactive transients to form the fluorescent 2',7'-dichlorofluorescein (DCF). The use of DCFH2-DA in hepatocyte-derived cell lines is more challenging because of membrane transport proteins that interfere with probe uptake and retention, among several other reasons. Cancer cells share some of the physiological and biochemical features with hepatocytes, so probe-related technical issues are applicable to cultured malignant cells as well. This study therefore analyzed the in vitro properties of DCFH2-DA in cultured human hepatocytes (HepG2 cells and differentiated and undifferentiated HepaRG cells) to identify methodological and technical features that could impair proper data analysis and interpretation. The main issues that were found and should therefore be accounted for in experimental design include the following: (1) both DCFH2-DA and DCF are taken up rapidly, (2) DCF is poorly retained in the cytosol and exits the cell, (3) the rate of DCFH2 oxidation is cell type-specific, (4) DCF fluorescence intensity is pH-dependent at pH < 7, and (5) the stability of DCFH2-DA in cell culture medium relies on medium composition. Based on the findings, the conditions for the use of DCFH2-DA in hepatocyte cell lines were optimized. Finally, the optimized protocol was reduced to practice and DCFH2-DA was applied to visualize and quantify oxidative stress in real time in HepG2 cells subjected to anoxia/reoxygenation as a source of reactive transients.
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Affiliation(s)
- Megan J Reiniers
- Jiaxing Key Laboratory for Photonanomedicine and Experimental Therapeutics, Department of Pharmaceutics, College of Medicine, Jiaxing University, Jiaxing, Zhejiang, P. R. China
- Department of Surgery, Haaglanden Medisch Centrum, The Hague, The Netherlands
| | - Lianne R de Haan
- Jiaxing Key Laboratory for Photonanomedicine and Experimental Therapeutics, Department of Pharmaceutics, College of Medicine, Jiaxing University, Jiaxing, Zhejiang, P. R. China
- Laboratory Experimental Oncology, Department of Pathology, Erasmus MC, Rotterdam, The Netherlands
| | - Laurens F Reeskamp
- Department of Vascular Medicine, Amsterdam UMC, Location AMC, Amsterdam, The Netherlands
| | - Mans Broekgaarden
- Team Cancer Targets and Experimental Therapeutics, Department Microenvironment Cell Plasticity and Signaling, Institute for Advanced Biosciences, Université de Grenoble-Alpes, Allée des Alpes, La Tronche, France
- INSERM U 1209, CNRS UMR 5309, Allée des Alpes, La Tronche, France
| | - Ruurdtje Hoekstra
- Tytgat Institute for Liver and Intestinal Research, Amsterdam UMC, Location AMC, Amsterdam, The Netherlands
| | - Rowan F van Golen
- Department of Gastroenterology and Hepatology, Leiden University Medical Center, Leiden, The Netherlands.
| | - Michal Heger
- Jiaxing Key Laboratory for Photonanomedicine and Experimental Therapeutics, Department of Pharmaceutics, College of Medicine, Jiaxing University, Jiaxing, Zhejiang, P. R. China.
- Laboratory Experimental Oncology, Department of Pathology, Erasmus MC, Rotterdam, The Netherlands.
- Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands.
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Reiniers MJ, de Haan LR, Reeskamp LF, Broekgaarden M, van Golen RF, Heger M. Analysis and Optimization of Conditions for the Use of 2',7'-Dichlorofluorescein Diacetate in Cultured Hepatocytes. Antioxidants (Basel) 2021; 10:antiox10050674. [PMID: 33925917 PMCID: PMC8147027 DOI: 10.3390/antiox10050674] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2021] [Revised: 04/11/2021] [Accepted: 04/15/2021] [Indexed: 12/27/2022] Open
Abstract
Numerous liver pathologies encompass oxidative stress as molecular basis of disease. The use of 2',7'-dichlorodihydrofluorescein-diacetate (DCFH2-DA) as fluorogenic redox probe is problematic in liver cell lines because of membrane transport proteins that interfere with probe kinetics, among other reasons. The properties of DCFH2-DA were analyzed in hepatocytes (HepG2, HepaRG) to characterize methodological issues that could hamper data interpretation and falsely skew conclusions. Experiments were focused on probe stability in relevant media, cellular probe uptake/retention/excretion, and basal oxidant formation and metabolism. DCFH2-DA was used under optimized experimental conditions to intravitally visualize and quantify oxidative stress in real-time in HepG2 cells subjected to anoxia/reoxygenation. The most important findings were that: (1) the non-fluorescent DCFH2-DA and the fluorescent DCF are rapidly taken up by hepatocytes, (2) DCF is poorly retained in hepatocytes, and (3) DCFH2 oxidation kinetics are cell type-specific. Furthermore, (4) DCF fluorescence intensity was pH-dependent at pH < 7 and (5) the stability of DCFH2-DA in cell culture medium relied on medium composition. The use of DCFH2-DA to measure oxidative stress in cultured hepatocytes comes with methodological and technical challenges, which were characterized and solved. Optimized in vitro and intravital imaging protocols were formulated to help researchers conduct proper experiments and draw robust conclusions.
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Affiliation(s)
- Megan J. Reiniers
- Jiaxing Key Laboratory for Photonanomedicine and Experimental Therapeutics, Department of Pharmaceutics, College of Medicine, Jiaxing University, Jiaxing 314001, China; (M.J.R.); (L.R.d.H.)
- Department of Surgery, Haaglanden Medisch Centrum, 2512 VA The Hague, The Netherlands
| | - Lianne R. de Haan
- Jiaxing Key Laboratory for Photonanomedicine and Experimental Therapeutics, Department of Pharmaceutics, College of Medicine, Jiaxing University, Jiaxing 314001, China; (M.J.R.); (L.R.d.H.)
- Laboratory of Experimental Oncology, Department of Pathology, Erasmus MC, 3015 GD Rotterdam, The Netherlands
| | - Laurens F. Reeskamp
- Department of Vascular Medicine, Amsterdam UMC, Location AMC, 1105 AZ Amsterdam, The Netherlands;
| | - Mans Broekgaarden
- Team Cancer Targets and Experimental Therapeutics, Department Microenvironment Cell Plasticity and Signaling, Institute for Advanced Biosciences, CNRS UMR 5309, Université de Grenoble-Alpes, Allée des Alpes, 38700 La Tronche, France;
- INSERM U 1209, Allée des Alpes, 38700 La Tronche, France
| | - Rowan F. van Golen
- Department of Gastroenterology and Hepatology, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands;
| | - Michal Heger
- Jiaxing Key Laboratory for Photonanomedicine and Experimental Therapeutics, Department of Pharmaceutics, College of Medicine, Jiaxing University, Jiaxing 314001, China; (M.J.R.); (L.R.d.H.)
- Laboratory of Experimental Oncology, Department of Pathology, Erasmus MC, 3015 GD Rotterdam, The Netherlands
- Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, 3584 CG Utrecht, The Netherlands
- Correspondence: or ; Tel.: +86-138-19345926 or +31-30-2533966
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3
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Michaelsen VS, Ribeiro RV, Ali A, Wang A, Gazzalle A, Keshavjee S, Cypel M. Safety of continuous 12-hour delivery of antimicrobial doses of inhaled nitric oxide during ex vivo lung perfusion. J Thorac Cardiovasc Surg 2020; 163:841-849.e1. [DOI: 10.1016/j.jtcvs.2020.11.150] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 11/20/2020] [Accepted: 11/27/2020] [Indexed: 11/25/2022]
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On the Anti-Cancer Effect of Cold Atmospheric Plasma and the Possible Role of Catalase-Dependent Apoptotic Pathways. Cells 2020; 9:cells9102330. [PMID: 33096638 PMCID: PMC7589812 DOI: 10.3390/cells9102330] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 10/14/2020] [Accepted: 10/19/2020] [Indexed: 01/24/2023] Open
Abstract
Cold atmospheric plasma (CAP) is a promising new agent for (selective) cancer treatment, but the underlying cause of the anti-cancer effect of CAP is not well understood yet. Among different theories and observations, one theory in particular has been postulated in great detail and consists of a very complex network of reactions that are claimed to account for the anti-cancer effect of CAP. Here, the key concept is a reactivation of two specific apoptotic cell signaling pathways through catalase inactivation caused by CAP. Thus, it is postulated that the anti-cancer effect of CAP is due to its ability to inactivate catalase, either directly or indirectly. A theoretical investigation of the proposed theory, especially the role of catalase inactivation, can contribute to the understanding of the underlying cause of the anti-cancer effect of CAP. In the present study, we develop a mathematical model to analyze the proposed catalase-dependent anti-cancer effect of CAP. Our results show that a catalase-dependent reactivation of the two apoptotic pathways of interest is unlikely to contribute to the observed anti-cancer effect of CAP. Thus, we believe that other theories of the underlying cause should be considered and evaluated to gain knowledge about the principles of CAP-induced cancer cell death.
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5
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Neubert E, Bach KM, Busse J, Bogeski I, Schön MP, Kruss S, Erpenbeck L. Blue and Long-Wave Ultraviolet Light Induce in vitro Neutrophil Extracellular Trap (NET) Formation. Front Immunol 2019; 10:2428. [PMID: 31708915 PMCID: PMC6823194 DOI: 10.3389/fimmu.2019.02428] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Accepted: 09/27/2019] [Indexed: 12/31/2022] Open
Abstract
Neutrophil Extracellular Traps (NETs) are produced by neutrophilic granulocytes and consist of decondensed chromatin decorated with antimicrobial peptides. They defend the organism against intruders and are released upon various stimuli including pathogens, mediators of inflammation, or chemical triggers. NET formation is also involved in inflammatory, cardiovascular, malignant diseases, and autoimmune disorders like rheumatoid arthritis, psoriasis, or systemic lupus erythematosus (SLE). In many autoimmune diseases like SLE or dermatomyositis, light of the ultraviolet-visible (UV-VIS) spectrum is well-known to trigger and aggravate disease severity. However, the underlying connection between NET formation, light exposure, and disease exacerbation remains elusive. We studied the effect of UVA (375 nm), blue (470 nm) and green (565 nm) light on NETosis in human neutrophils ex vivo. Our results show a dose- and wavelength-dependent induction of NETosis. Light-induced NETosis depended on the generation of extracellular reactive oxygen species (ROS) induced by riboflavin excitation and its subsequent reaction with tryptophan. The light-induced NETosis required both neutrophil elastase (NE) as well as myeloperoxidase (MPO) activation and induced histone citrullination. These findings suggest that NET formation as a response to light could be the hitherto missing link between elevated susceptibility to NET formation in autoimmune patients and photosensitivity for example in SLE and dermatomyositis patients. This novel connection could provide a clue for a deeper understanding of light-sensitive diseases in general and for the development of new pharmacological strategies to avoid disease exacerbation upon light exposure.
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Affiliation(s)
- Elsa Neubert
- Department of Dermatology, Venereology and Allergology, University Medical Center Göttingen, Göttingen, Germany.,Institute of Physical Chemistry, Göttingen University, Göttingen, Germany
| | - Katharina Marie Bach
- Department of Dermatology, Venereology and Allergology, University Medical Center Göttingen, Göttingen, Germany
| | - Julia Busse
- Department of Dermatology, Venereology and Allergology, University Medical Center Göttingen, Göttingen, Germany
| | - Ivan Bogeski
- Institute of Cardiovascular Physiology, University Medical Center Göttingen, Göttingen, Germany
| | - Michael P Schön
- Department of Dermatology, Venereology and Allergology, University Medical Center Göttingen, Göttingen, Germany.,Lower Saxony Institute of Occupational Dermatology, University Medical Center Göttingen, Göttingen, Germany
| | - Sebastian Kruss
- Institute of Physical Chemistry, Göttingen University, Göttingen, Germany.,Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Göttingen, Germany
| | - Luise Erpenbeck
- Department of Dermatology, Venereology and Allergology, University Medical Center Göttingen, Göttingen, Germany
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6
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Medina M, Rizo A, Dinh D, Chau B, Omidvar M, Juarez A, Ngo J, Johnson HA. MopA, the Mn Oxidizing Protein From Erythrobacter sp. SD-21, Requires Heme and NAD + for Mn(II) Oxidation. Front Microbiol 2018; 9:2671. [PMID: 30487779 PMCID: PMC6247904 DOI: 10.3389/fmicb.2018.02671] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Accepted: 10/19/2018] [Indexed: 11/15/2022] Open
Abstract
Bacterial manganese (Mn) oxidation is catalyzed by a diverse group of microbes and can affect the fate of other elements in the environment. Yet, we understand little about the enzymes that catalyze this reaction. The Mn oxidizing protein MopA, from Erythrobacter sp. strain SD-21, is a heme peroxidase capable of Mn(II) oxidation. Unlike Mn oxidizing multicopper oxidase enzymes, an understanding of MopA is very limited. Sequence analysis indicates that MopA contains an N-terminal heme peroxidase domain and a C-terminal calcium binding domain. Heterologous expression and nickel affinity chromatography purification of the N-terminal peroxidase domain (MopA-hp) from Erythrobacter sp. strain SD-21 led to partial purification. MopA-hp is a heme binding protein that requires heme, NAD+, and calcium (Ca2+) for activity. Mn oxidation is also stimulated by the presence of pyrroloquinoline quinone. MopA-hp has a KM for Mn(II) of 154 ± 46 μM and kcat = 1.6 min−1. Although oxygen requiring MopA-hp is homologous to peroxidases based on sequence, addition of hydrogen peroxide and hydrogen peroxide scavengers had little effect on Mn oxidation, suggesting this is not the oxidizing agent. These studies provide insight into the mechanism by which MopA oxidizes Mn.
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Affiliation(s)
- Michael Medina
- Department of Biological Science, Center for Applied Biotechnology Studies, California State University Fullerton, Fullerton, CA, United States
| | - Antonia Rizo
- Department of Biological Science, Center for Applied Biotechnology Studies, California State University Fullerton, Fullerton, CA, United States
| | - David Dinh
- Department of Biological Science, Center for Applied Biotechnology Studies, California State University Fullerton, Fullerton, CA, United States
| | - Briana Chau
- Department of Biological Science, Center for Applied Biotechnology Studies, California State University Fullerton, Fullerton, CA, United States
| | - Moussa Omidvar
- Department of Biological Science, Center for Applied Biotechnology Studies, California State University Fullerton, Fullerton, CA, United States
| | - Andrew Juarez
- Department of Biological Science, Center for Applied Biotechnology Studies, California State University Fullerton, Fullerton, CA, United States
| | - Julia Ngo
- Department of Biological Science, Center for Applied Biotechnology Studies, California State University Fullerton, Fullerton, CA, United States
| | - Hope A Johnson
- Department of Biological Science, Center for Applied Biotechnology Studies, California State University Fullerton, Fullerton, CA, United States
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7
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Kagenishi T, Yokawa K, Baluška F. MES Buffer Affects Arabidopsis Root Apex Zonation and Root Growth by Suppressing Superoxide Generation in Root Apex. FRONTIERS IN PLANT SCIENCE 2016; 7:79. [PMID: 26925066 PMCID: PMC4757704 DOI: 10.3389/fpls.2016.00079] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Accepted: 01/16/2016] [Indexed: 05/29/2023]
Abstract
In plants, growth of roots and root hairs is regulated by the fine cellular control of pH and reactive oxygen species (ROS). MES, 2-(N-morpholino)ethanesulfonic acid as one of the Good's buffers has broadly been used for buffering medium, and it is thought to suit for plant growth with the concentration at 0.1% (w/v) because the buffer capacity of MES ranging pH 5.5-7.0 (for Arabidopsis, pH 5.8). However, many reports have shown that, in nature, roots require different pH values on the surface of specific root apex zones, namely meristem, transition zone, and elongation zone. Despite the fact that roots always grow on a media containing buffer molecule, little is known about impact of MES on root growth. Here, we have checked the effects of different concentrations of MES buffer using growing roots of Arabidopsis thaliana. Our results show that 1% of MES significantly inhibited root growth, the number of root hairs and length of meristem, whereas 0.1% promoted root growth and root apex area (region spanning from the root tip up to the transition zone). Furthermore, superoxide generation in root apex disappeared at 1% of MES. These results suggest that MES disturbs normal root morphogenesis by changing the ROS homeostasis in root apex.
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Affiliation(s)
- Tomoko Kagenishi
- Institute of Cellular and Molecular Botany, University of BonnBonn, Germany
| | - Ken Yokawa
- Institute of Cellular and Molecular Botany, University of BonnBonn, Germany
- Department of Biological Sciences, Tokyo Metropolitan UniversityTokyo, Japan
| | - František Baluška
- Institute of Cellular and Molecular Botany, University of BonnBonn, Germany
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Hamilton NB, Kolodziejczyk K, Kougioumtzidou E, Attwell D. Proton-gated Ca(2+)-permeable TRP channels damage myelin in conditions mimicking ischaemia. Nature 2016; 529:523-7. [PMID: 26760212 PMCID: PMC4733665 DOI: 10.1038/nature16519] [Citation(s) in RCA: 125] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Accepted: 12/07/2015] [Indexed: 11/09/2022]
Abstract
The myelin sheaths wrapped around axons by oligodendrocytes are crucial for brain function. In ischaemia myelin is damaged in a Ca(2+)-dependent manner, abolishing action potential propagation. This has been attributed to glutamate release activating Ca(2+)-permeable N-methyl-D-aspartate (NMDA) receptors. Surprisingly, we now show that NMDA does not raise the intracellular Ca(2+) concentration ([Ca(2+)]i) in mature oligodendrocytes and that, although ischaemia evokes a glutamate-triggered membrane current, this is generated by a rise of extracellular [K(+)] and decrease of membrane K(+) conductance. Nevertheless, ischaemia raises oligodendrocyte [Ca(2+)]i, [Mg(2+)]i and [H(+)]i, and buffering intracellular pH reduces the [Ca(2+)]i and [Mg(2+)]i increases, showing that these are evoked by the rise of [H(+)]i. The H(+)-gated [Ca(2+)]i elevation is mediated by channels with characteristics of TRPA1, being inhibited by ruthenium red, isopentenyl pyrophosphate, HC-030031, A967079 or TRPA1 knockout. TRPA1 block reduces myelin damage in ischaemia. These data suggest that TRPA1-containing ion channels could be a therapeutic target in white matter ischaemia.
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Affiliation(s)
- Nicola B Hamilton
- Department of Neuroscience, Physiology &Pharmacology, University College London, Gower St., London WC1E 6BT, UK
| | - Karolina Kolodziejczyk
- Department of Neuroscience, Physiology &Pharmacology, University College London, Gower St., London WC1E 6BT, UK
| | - Eleni Kougioumtzidou
- Department of Neuroscience, Physiology &Pharmacology, University College London, Gower St., London WC1E 6BT, UK
| | - David Attwell
- Department of Neuroscience, Physiology &Pharmacology, University College London, Gower St., London WC1E 6BT, UK
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9
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Harding JL, Reynolds MM. Accurate Nitric Oxide Measurements from Donors in Cell Media: Identification of Scavenging Agents. Anal Chem 2014; 86:2025-32. [DOI: 10.1021/ac403174e] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Jacqueline L. Harding
- Department
of Chemistry and ‡School of Biomedical Engineering, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Melissa M. Reynolds
- Department
of Chemistry and ‡School of Biomedical Engineering, Colorado State University, Fort Collins, Colorado 80523, United States
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Overview of significant examples of electrochemical sensor arrays designed for detection of nitric oxide and relevant species in a biological environment. Anal Bioanal Chem 2013; 405:3475-88. [PMID: 23334219 DOI: 10.1007/s00216-012-6671-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Revised: 12/04/2012] [Accepted: 12/18/2012] [Indexed: 12/15/2022]
Abstract
Ultramicroelectrode sensor arrays in which each electrode, or groups of electrodes, are individually addressable are of particular interest for detection of several species concomitantly, by using specific sensing chemistry for each analyte, or for mapping of one analyte to achieve spatio-temporal analysis. Microfabrication technology, for example photolitography, is usually used for fabrication of these arrays. The most widespread geometries produced by photolithography are thin-film microdisc electrode arrays with different electrode distributions (square, hexagonal, or random). In this paper we review different electrochemical sensor arrays developed to monitor, in vivo, NO levels produced by cultured cells or sliced tissues. Simultaneous detection of NO and analytes interacting with or released at the same time as NO is also discussed.
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Dendroulakis V, Russell BS, Elmquist CE, Trudel LJ, Wogan GN, Deen WM, Dedon PC. A system for exposing molecules and cells to biologically relevant and accurately controlled steady-state concentrations of nitric oxide and oxygen. Nitric Oxide 2012; 27:161-8. [PMID: 22728703 DOI: 10.1016/j.niox.2012.06.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Revised: 05/14/2012] [Accepted: 06/15/2012] [Indexed: 12/30/2022]
Abstract
Nitric oxide (NO) plays key roles in cell signaling and physiology, with diverse functions mediated by NO concentrations varying over three orders-of-magnitude. In spite of this critical concentration dependence, current approaches to NO delivery in vitro result in biologically irrelevant and poorly controlled levels, with hyperoxic conditions imposed by ambient air. To solve these problems, we developed a system for controlled delivery of NO and O(2) over large concentration ranges to mimic biological conditions. Here we describe the fabrication, operation and calibration of the delivery system. We then describe applications for delivery of NO and O(2) into cell culture media, with a comparison of experimental results and predictions from mass transfer models that predict the steady-state levels of various NO-derived reactive species. We also determined that components of culture media do not affect the steady-state levels of NO or O(2) in the device. This system provides critical control of NO delivery for in vitro models of NO biology and chemistry.
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Affiliation(s)
- Vasileios Dendroulakis
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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12
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Priyadarshini M, Khan MS, Bano B. Aggregation and inactivation of pancreatic cystatin by riboflavin-derived singlet oxygen and flavin triplet state: Polyphenols as preventive agents. J Biochem Mol Toxicol 2012; 26:187-92. [DOI: 10.1002/jbt.20423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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13
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Nitric oxide and neuronal death. Nitric Oxide 2010; 23:153-65. [DOI: 10.1016/j.niox.2010.06.001] [Citation(s) in RCA: 280] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2009] [Revised: 06/04/2010] [Accepted: 06/07/2010] [Indexed: 12/14/2022]
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14
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Maguire A, Morrissey B, Walsh JE, Lyng FM. Medium-mediated effects increase cell killing in a human keratinocyte cell line exposed to solar-simulated radiation. Int J Radiat Biol 2010; 87:98-111. [PMID: 20973658 DOI: 10.3109/09553002.2010.518210] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE The objective of this study was to investigate whether cell culture medium is a biologically relevant exposure medium that can be employed in non-ionising photobiological investigations. METHODS The effect of solar-simulated irradiation on cell culture medium and its ability to elicit cell death was studied. The role of reactive oxygen species (ROS), cell secreted factors, and the contribution of individual components of the medium were investigated. RESULTS Cell death was found to be primarily mediated through the formation of ROS via riboflavin photosensitisation and degradation in the cell culture medium. Phenol red was found to significantly reduce the cell killing ability of riboflavin. Exposures in riboflavin-free medium resulted in significantly increased cell survival compared to identical exposures in riboflavin containing medium. CONCLUSIONS This study has shown that solar radiation toxicity is augmented by cell culture medium due to the presence of riboflavin. Results suggest that exposures performed in phenol red-free medium may serve to increase phototoxic effects if riboflavin is present. Riboflavin-free media is recommended for solar radiation investigations to eliminate concerns regarding riboflavin photosensitisation and nutrient deprivation.
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Affiliation(s)
- Alanna Maguire
- Radiation and Environmental Science Centre (RESC), Focas Research Institute, Dublin Institute of Technology, Ireland
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15
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Chin MP, Deen WM. Prediction of nitric oxide concentrations in melanomas. Nitric Oxide 2010; 23:319-26. [PMID: 20854923 DOI: 10.1016/j.niox.2010.09.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2010] [Revised: 06/16/2010] [Accepted: 09/13/2010] [Indexed: 11/30/2022]
Abstract
The presence of iNOS and nitrotyrosine in cutaneous melanomas has been correlated with poor survival rates of patients, suggesting that NO plays a role in the tumor pathophysiology. However, the concentrations of NO that melanoma cells are exposed to in vivo have been unknown. To provide cell kinetic data for use in predicting those concentrations, synthesis and consumption of NO was examined in A375 melanoma cells. Nitric oxide synthesis was undetectable. The rate of intracellular NO consumption was determined by continuous monitoring of NO concentrations following injection of NO solutions in a closed chamber. After correcting for autoxidation and consumption from media-generated O(2)(-), the rate constant obtained for cellular consumption was 7.1±1.1 s(-1). This information was combined with previous data on macrophage NO kinetics to develop a mathematical model to predict NO levels in cutaneous melanomas. Synthesis of NO by macrophages in the stroma was found to give a maximum concentration at the tumor periphery of 0.2 μM. Because of the high rates of cellular consumption, the elevation in NO concentration is predicted to be very localized, approximately 90% of the concentration decay occurring within 30 μm of the tumor edge. High NO concentrations at the periphery of a melanoma may contribute to metastasis by stimulating cell proliferation, inhibiting apoptosis, or acting as a lymphangiogenic factor.
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Affiliation(s)
- Melanie P Chin
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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Chin MP, Schauer DB, Deen WM. Nitric oxide, oxygen, and superoxide formation and consumption in macrophages and colonic epithelial cells. Chem Res Toxicol 2010; 23:778-87. [PMID: 20201482 DOI: 10.1021/tx900415k] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Knowledge of the rates at which macrophages and epithelial cells synthesize NO is critical for predicting the concentrations of NO and other reactive nitrogen species in colonic crypts during inflammation, and elucidating the linkage between inflammatory bowel disease, NO, and cancer. Macrophage-like RAW264.7 cells, primary bone marrow-derived macrophages (BMDM), and HCT116 colonic epithelial cells were subjected to simulated inflammatory conditions, and rates of formation and consumption were determined for NO, O(2), and O(2)(-). Production rates of NO were determined in either of two ways: continuous monitoring of NO concentrations in a closed chamber with corrections for autoxidation, or NO(2)(-) accumulation measurements in an open system with corrections for diffusional losses of NO. The results obtained using the two methods were in excellent agreement. Rates of NO synthesis (2.3 +/- 0.6 pmol s(-1) 10(6) cells(-1)), NO consumption (1.3 +/- 0.3 s(-1)), and O(2) consumption (59 +/- 17 pmol s(-1) 10(6) cells(-1) when NO is negligible) for activated BMDM were indistinguishable from those of activated RAW264.7 cells. NO production rates calculated from NO(2)(-) accumulation data for HCT116 cells infected with Helicobacter cinaedi (3.9 +/- 0.1 pmol s(-1) 10(6) cells(-1)) were somewhat greater than those of RAW264.7 macrophages infected under similar conditions (2.6 +/- 0.1 pmol s(-1) 10(6) cells(-1)). Thus, RAW264.7 cells have NO kinetics nearly identical to those of primary macrophages, and stimulated epithelial cells are capable of synthesizing NO at rates comparable to those of macrophages. Using these cellular kinetic parameters, simulations of NO diffusion and reaction in a colonic crypt during inflammation predict maximum NO concentrations of about 0.2 microM at the base of a crypt.
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Affiliation(s)
- Melanie P Chin
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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17
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Evaluation of the antioxidant properties of N-acetylcysteine in human platelets: prerequisite for bioconversion to glutathione for antioxidant and antiplatelet activity. J Cardiovasc Pharmacol 2010; 54:319-26. [PMID: 19668088 DOI: 10.1097/fjc.0b013e3181b6e77b] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
N-Acetylcysteine (NAC) is a frequently used "antioxidant" in vitro, but the concentrations applied rarely correlate with those encountered with oral dosing in vivo. Here, we investigated the in vitro antioxidant and antiplatelet properties of NAC at concentrations (10-100 microM) that are achievable in plasma with tolerable oral dosing. The impact of NAC pretreatment (2 hours) on aggregation of platelets from healthy volunteers in response to thrombin and adenosine diphosphate and on platelet-derived nitric oxide (NO) was examined. NAC was found to be a weak reducing agent and a poor antioxidant compared with glutathione (reduced form) (GSH). However, platelets treated with NAC showed enhanced antioxidant activity and depression of reactive oxygen species generation associated with increases in intraplatelet GSH levels. An approximately 2-fold increase in NO synthase-derived nitrite was observed with 10 microM NAC treatment, but the effect was not concentration dependent. Finally, NAC significantly reduced both thrombin-induced and adenosine diphosphate-induced platelet aggregation. NAC should be considered a weak antioxidant that requires prior conversion to GSH to convey antioxidant and antithrombotic benefit at therapeutically relevant concentrations. Our results suggest that NAC might be an effective antiplatelet agent in conditions where increased oxidative stress contributes to heightened risk of thrombosis but only if the intraplatelet machinery to convert it to GSH is functional.
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New insight into the functioning of nitric oxide-receptive guanylyl cyclase: physiological and pharmacological implications. Mol Cell Biochem 2009; 334:221-32. [PMID: 20012469 DOI: 10.1007/s11010-009-0318-8] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2009] [Accepted: 11/04/2009] [Indexed: 10/20/2022]
Abstract
The cellular counterpart of the "soluble" guanylyl cyclase found in tissue homogenates over 30 years ago is now recognized as the physiological receptor for nitric oxide (NO). The ligand-binding site is a prosthetic haem group that, when occupied by NO, induces a conformational change in the protein that propagates to the catalytic site, triggering conversion of GTP into cGMP. This review focuses on recent research that takes this basic information forward to the beginnings of a quantitative depiction of NO signal transduction, analogous to that achieved for other major transmitters. At its foundation is an explicit enzyme-linked receptor mechanism for NO-activated guanylyl cyclase that replicates all its main properties. In cells, NO signal transduction is subject to additional, activity-dependent modifications, notably through receptor desensitization and changes in the activity of cGMP-hydrolyzing phosphodiesterases. The measurement of these parameters under varying conditions in rat platelets has made it possible to formulate a cellular model of NO-cGMP signaling. The model helps explain cellular responses to NO and their modification by therapeutic agents acting on the guanylyl cyclase or phosphodiesterase limbs of the pathway.
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James LR, Griffiths CH, Garthwaite J, Bellamy TC. Inhibition of nitric oxide-activated guanylyl cyclase by calmodulin antagonists. Br J Pharmacol 2009; 158:1454-64. [PMID: 19845679 DOI: 10.1111/j.1476-5381.2009.00416.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND AND PURPOSE Nitric oxide (NO) controls numerous physiological processes by activation of its receptor, guanylyl cyclase (sGC), leading to the accumulation of 3'-5' cyclic guanosine monophosphate (cGMP). Ca(2+)-calmodulin (CaM) regulates both NO synthesis by NO synthase and cGMP hydrolysis by phosphodiesterase-1. We report that, unexpectedly, the CaM antagonists, calmidazolium, phenoxybenzamine and trifluoperazine, also inhibited cGMP accumulation in cerebellar cells evoked by an exogenous NO donor, with IC(50) values of 11, 80 and 180 microM respectively. Here we sought to elucidate the underlying mechanism(s). EXPERIMENTAL APPROACH We used cerebellar cell suspensions to determine the influence of CaM antagonists on all steps of the NO-cGMP pathway. Homogenized tissue and purified enzyme were used to test effects of calmidazolium on sGC activity. KEY RESULTS Inhibition of cGMP accumulation in the cells did not depend on changes in intracellular Ca(2+) concentration. Degradation of cGMP and inactivation of NO were both inhibited by the CaM antagonists, ruling out increased loss of cGMP or NO as explanations. Instead, calmidazolium directly inhibited purified sGC (IC(50)= 10 microM). The inhibition was not in competition with NO, nor did it arise from displacement of the haem moiety from sGC. Calmidazolium decreased enzyme V(max) and K(m), indicating that it acts in an uncompetitive manner. CONCLUSIONS AND IMPLICATIONS The disruption of every stage of NO signal transduction by common CaM antagonists, unrelated to CaM antagonism, cautions against their utility as pharmacological tools. More positively, the compounds exemplify a novel class of sGC inhibitors that, with improved selectivity, may be therapeutically valuable.
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20
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Electrochemical quantification of reactive oxygen and nitrogen: challenges and opportunities. Anal Bioanal Chem 2009; 394:95-105. [DOI: 10.1007/s00216-009-2692-1] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2008] [Revised: 01/29/2009] [Accepted: 02/09/2009] [Indexed: 01/09/2023]
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21
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Wardman P. Use of the Dichlorofluorescein Assay to Measure “Reactive Oxygen Species”. Radiat Res 2008; 170:406-7. [DOI: 10.1667/rr1439a.1] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2008] [Indexed: 11/03/2022]
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22
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Miller C, McMullin B, Ghaffari A, Stenzler A, Pick N, Roscoe D, Ghahary A, Road J, Av-Gay Y. Gaseous nitric oxide bactericidal activity retained during intermittent high-dose short duration exposure. Nitric Oxide 2008; 20:16-23. [PMID: 18789393 DOI: 10.1016/j.niox.2008.08.002] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2008] [Revised: 08/06/2008] [Accepted: 08/08/2008] [Indexed: 11/19/2022]
Abstract
Previously, we have shown that gaseous Nitric oxide (gNO) has great potential as an effective topical anti-infective agent for non-healing wounds due to its non-specific antimicrobial properties. These same antimicrobial attributes may be useful for pulmonary infections. However, gNO would have limited usefulness as an inhaled antimicrobial agent as continuous exposure to the concentration required for a bactericidal effect (160-200 ppm) leads to methemoglobinemia. To overcome this problem, we investigated whether a thirty minute exposure of 160 ppm every four hours would retain the same antimicrobial effect as continuous delivery. In vitro, exposure of clinical multi-drug resistant Staphylococcus aureus and Escherichia coli strains isolated from the lungs of nosocomial pneumonia patients and a lethal antibiotic-resistant strain of Pseudomonas aeruginosa, isolated from a deceased cystic fibrosis patient resulted in over a 5 log(10) reduction in bacterial load after multiple thirty minute treatments (4 cycles) every four hours to 160 ppm gNO. The intermittent regimen required 320 (SD=0)ppm h for 100% lethality whereas the continuous exposure required 800 (SD=160)ppm h. We have also shown that selection for a gNO resistant phenotype did not lead to decrease sensitivity to gNO therapy (p>0.05). In addition, no host cellular toxicity was observed in human THP-1 monocytes and macrophages following intermittent delivery of a high concentration of gNO, and the proliferation and migration of pulmonary epithelial cells was not adversely affected by the administration of intermittent high-dose gNO. These results justify further studies that should focus on whether intermittent delivery of 160 ppm of gNO every four hours can technically be administered while keeping inhaled NO(2) levels less than 2 ppm and methemoglobin saturation less than 2.5 percent.
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Affiliation(s)
- Chris Miller
- Division of Infectious Diseases, Department of Medicine, Vancouver Coastal Health at Vancouver General Hospital, University of British Columbia, 2733 Heather Street, Vancouver, BC, Canada.
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23
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Abstract
As a chemical transmitter in the mammalian central nervous system, nitric oxide (NO) is still thought a bit of an oddity, yet this role extends back to the beginnings of the evolution of the nervous system, predating many of the more familiar neurotransmitters. During the 20 years since it became known, evidence has accumulated for NO subserving an increasing number of functions in the mammalian central nervous system, as anticipated from the wide distribution of its synthetic and signal transduction machinery within it. This review attempts to probe beneath those functions and consider the cellular and molecular mechanisms through which NO evokes short- and long-term modifications in neural performance. With any transmitter, understanding its receptors is vital for decoding the language of communication. The receptor proteins specialised to detect NO are coupled to cGMP formation and provide an astonishing degree of amplification of even brief, low amplitude NO signals. Emphasis is given to the diverse ways in which NO receptor activation initiates changes in neuronal excitability and synaptic strength by acting at pre- and/or postsynaptic locations. Signalling to non-neuronal cells and an unexpected line of communication between endothelial cells and brain cells are also covered. Viewed from a mechanistic perspective, NO conforms to many of the rules governing more conventional neurotransmission, particularly of the metabotropic type, but stands out as being more economical and versatile, attributes that presumably account for its spectacular evolutionary success.
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Affiliation(s)
- John Garthwaite
- Wolfson Institute for Biomedical Research, University College London, Gower Street, London WCIE 6BT, UK.
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Robinson MA, Baumgardner JE, Good VP, Otto CM. Physiological and hypoxic O2 tensions rapidly regulate NO production by stimulated macrophages. Am J Physiol Cell Physiol 2008; 294:C1079-87. [PMID: 18272818 DOI: 10.1152/ajpcell.00469.2007] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Nitric oxide (NO) production by inducible NO synthase (iNOS) is dependent on O(2) availability. The duration and degree of hypoxia that limit NO production are poorly defined in cultured cells. To investigate short-term O(2)-mediated regulation of NO production, we used a novel forced convection cell culture system to rapidly (response time of 1.6 s) and accurately (+/-1 Torr) deliver specific O(2) tensions (from <1 to 157 Torr) directly to a monolayer of LPS- and IFNgamma-stimulated RAW 264.7 cells while simultaneously measuring NO production via an electrochemical probe. Decreased O(2) availability rapidly (<or=30 s) and reversibly decreased NO production with an apparent K(m)O(2) of 22 (SD 6) Torr (31 microM) and a V(max) of 4.9 (SD 0.4) nmol min(-1) 10(-6) cells. To explore potential mechanisms of decreased NO production during hypoxia, we investigated O(2)-dependent changes in iNOS protein concentration, iNOS dimerization, and cellular NO consumption. iNOS protein concentration was not affected (P = 0.895). iNOS dimerization appeared to be biphasic [6 Torr (P = 0.008) and 157 Torr (P = 0.258) >36 Torr], but it did not predict NO production. NO consumption was minimal at high O(2) and NO tensions and negligible at low O(2) and NO tensions. These results are consistent with O(2) substrate limitation as a regulatory mechanism during brief hypoxic exposure. The rapid and reversible effects of physiological and pathophysiological O(2) tensions suggest that O(2) tension has the potential to regulate NO production in vivo.
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Affiliation(s)
- Mary A Robinson
- Department of Clinical Studies-Philadelphia, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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25
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Knoch ME, Hartnett KA, Hara H, Kandler K, Aizenman E. Microglia induce neurotoxicity via intraneuronal Zn(2+) release and a K(+) current surge. Glia 2008; 56:89-96. [PMID: 17955552 DOI: 10.1002/glia.20592] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Microglial cells are critical components of the injurious cascade in a large number of neurodegenerative diseases. However, the precise molecular mechanisms by which microglia mediate neuronal cell death have not been fully delineated. We report here that reactive species released from activated microglia induce the liberation of Zn(2+) from intracellular stores in cultured cortical neurons, with a subsequent enhancement in neuronal voltage-gated K(+) currents, two events that have been intimately linked to apoptosis. Both the intraneuronal Zn(2+) release and the K(+) current surge could be prevented by the NADPH oxidase inhibitor apocynin, the free radical scavenging mixture of superoxide dismutase and catalase, as well as by 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrinato iron(III) chloride. The enhancement of K(+) currents was prevented by neuronal overexpression of metallothionein III or by expression of a dominant negative (DN) vector for the upstream mitogen-activated protein kinase apoptosis signal regulating kinase-1 (ASK-1). Importantly, neurons overexpressing metallothionein-III or transfected with DN vectors for ASK-1 or Kv2.1-encoded K(+) channels were resistant to microglial-induced toxicity. These results establish a direct link between microglial-generated oxygen and nitrogen reactive products and neuronal cell death mediated by intracellular Zn(2+) release and a surge in K(+) currents.
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Affiliation(s)
- Megan E Knoch
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, USA
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26
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Diazeniumdiolate reactivity in model membrane systems. Nitric Oxide 2007; 18:113-21. [PMID: 18068133 DOI: 10.1016/j.niox.2007.11.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2007] [Revised: 11/08/2007] [Accepted: 11/13/2007] [Indexed: 11/24/2022]
Abstract
The effect of small unilamellar phospholipid vesicles on the acid-catalyzed dissociation of nitric oxide from diazeniumdiolate ions, R(1)R(2)N[N(O)NO](-), [1: R(1)=H(2)N(CH(2))(3)-, R(2)=H(2)N(CH(2))(3)NH(CH(2))(4)-; 2: R(1)=R(2)=H(2)N(CH(2))(3)-; 3: R(1)=n-butyl-, R(2)=n-butyl-NH2+(CH(2))(6)-; 4: R(1)=R(2)=nPr-] has been examined at pH 7.4 and 37 degrees C. NO release was catalyzed by anionic liposomes (DPPG, DOPG, DMPS, POPS and DOPA) and by mixed phosphatidylglycerol/phosphatidylcholine (DPPG/DPPC and DOPG/DPPC) covesicles, while cationic liposomes derived from 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) and the zwitterionic liposome DMPC did not significantly affect the dissociation rates of the substrates examined. Enhancement of the dissociation rate constant in DPPG liposome media (0.010M phosphate buffer, pH 7.4, 37 degrees C) at 10mM phosphoglycerol levels, ranged from 37 for 1 to 1.2 for the anionic diazeniumdiolate 4, while DOPA effected the greatest rate enhancement, achieving 49-fold rate increases with 1 under similar conditions. The observed catalysis decreases with increase in the bulk concentration of electrolytes in the reaction media. Quantitative analysis of catalytic effects has been obtained through the application of pseudo-phase kinetic models and equilibrium binding constants at different liposome interfaces are compared. The stoichiometry of nitric oxide release from 1 and 2 in DPPG/DPPC liposome media has been obtained through oxyhemoglobin assay. DPPG=1,2-dipalmitoyl-sn-glycero-3-[phospho-rac-(1-glycerol)], DOPG=1,2-dioleoyl-sn-glycero-3-[phospho-rac-(1-glycerol)], DMPS=1,2-dimyristoyl-sn-glycero-3-[phospho-l-serine], POPS=1-palmitoyl-2-oleoyl-sn-glycero-3-[phospho-l-serine], DOPA=1,2-dioleoyl-sn-glycero-3-phosphate; DPPC=1,2-dipalmitoyl-sn-glycero-3-phosphocholine, DMPC=1,2-dimyristoyl-sn-glycero-3-phosphocholine, DOTAP=1,2-dioleoyl-3-trimethylammonium-propane.
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27
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Baker CJ, Mock NM, Roberts DP, Deahl KL, Hapeman CJ, Schmidt WF, Kochansky J. Interference by Mes [2-(4-morpholino)ethanesulfonic acid] and related buffers with phenolic oxidation by peroxidase. Free Radic Biol Med 2007; 43:1322-7. [PMID: 17893045 DOI: 10.1016/j.freeradbiomed.2007.07.020] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2007] [Revised: 07/20/2007] [Accepted: 07/24/2007] [Indexed: 11/26/2022]
Abstract
While characterizing the kinetic parameters of apoplastic phenolic oxidation by peroxidase, we found anomalies caused by the Mes [2-(4-morpholino)ethanesulfonic acid] buffer being used. In the presence of Mes, certain phenolics appeared not to be oxidized by peroxidase, yet the oxidant, H(2)O(2), was utilized. This anomaly seems to be due to the recycling of the phenolic substrate. The reaction is relatively inefficient, but at buffer concentrations of 10 mM or greater the recycling effect is nearly 100% with substrate concentrations less than 100 microM. The recycling effect is dependent on substrate structure, occurring with 4'-hydroxyacetophenone but not with 3',5'-dimethoxy-4'-hydroxyacetophenone (acetosyringone). Characterization of the reaction parameters suggests that the phenoxyl radical from the peroxidase reaction interacts with Mes, causing the reduction and regeneration of the phenol. Similar responses occurred with related buffers such as Hepes [4-(2-hydroxyethyl)piperazine-1-ethanesulfonic acid] and Pipes [piperazine-1,4-bis(2-ethanesulfonic acid)]. Results from this work and other reports in the literature indicate that great care is required in interpreting any results involving these buffers under oxidizing conditions.
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Affiliation(s)
- C Jacyn Baker
- Molecular Plant Pathology Lab, U.S. Department of Agriculture, Beltsville, MD 20705, USA.
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28
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Roy B, Garthwaite J. Nitric oxide activation of guanylyl cyclase in cells revisited. Proc Natl Acad Sci U S A 2006; 103:12185-90. [PMID: 16882726 PMCID: PMC1567716 DOI: 10.1073/pnas.0602544103] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Nitric oxide (NO) elicits physiological effects in cells largely by activating guanylyl cyclase (GC)-coupled receptors, leading to cGMP accumulation. Like other receptor-coupled effector mechanisms, NO stimulation of GC activity was previously considered to be a graded, concentration-dependent response, with deactivation following swiftly once the agonist disappeared. Recently, a new and unconventional mechanism has been proposed from experiments on purified protein [Cary, S. P. L., Winger, J. A. & Marletta, M. A. (2005) Proc. Natl. Acad. Sci. USA 102, 13064-13069]. It was concluded that GC in vivo will display a dual regulation by NO: a long-lasting tonic activity (10-20% of maximum) due to persistent occupation by NO of the heme binding site and phasic activity due to engagement of another unidentified, lower affinity site. The hypothesis was first tested by monitoring GC activity in rat platelets maintained in vitro and exposed to calibrated NO transients. The kinetics was as expected for a single binding site for NO (EC(50) = 10 nM), with activation and deactivation of enzyme activity conforming to the predictions of a simple receptor model. No tonic GC activity attributable to long-term NO binding was detected after exposure to the full range of active NO concentrations (peaking at 2-500 nM). Comparable results were obtained by using neural cells isolated from the cerebellum. After exposure to high NO concentrations, persistent GC activity could be recorded, but this activity was caused artifactually by secondary NO sources being formed in the medium. The new scheme for regulation of GC activity by NO is of doubtful relevance to cells.
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Affiliation(s)
- Brijesh Roy
- Wolfson Institute for Biomedical Research, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - John Garthwaite
- Wolfson Institute for Biomedical Research, University College London, Gower Street, London WC1E 6BT, United Kingdom
- To whom correspondence should be addressed. E-mail:
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29
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Boullerne AI, Benjamins JA. Nitric oxide synthase expression and nitric oxide toxicity in oligodendrocytes. Antioxid Redox Signal 2006; 8:967-80. [PMID: 16771686 DOI: 10.1089/ars.2006.8.967] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Oligodendrocytes (OLG) have more complex interactions with nitric oxide (NO) than initially suspected. Historically, OLG were seen only as targets of high NO levels released from other cells. Expression of nitric oxide synthase type II (NOS-2) in primary cultures of OLGs stimulated by cytokines led to controversy due to the presence of small numbers of microglia, cells also inducible for NOS-2 expression. The present review summarizes the findings that immature OLG express NOS-2, but that they do not in their most mature stage in culture as membrane sheet-bearing cells. This raises questions about the regulation of NOS-2 expression in OLG. Additionally, novel data are presented on NOS-3 expression in cultured OLG. If confirmed in vivo, this finding suggests that constitutive NOS-3 expression may play a key role in OLG injury due to its activation by calcium, in interaction with pathways mediating glutamate toxicity. The authors discuss in vivo NO levels to place in vitro findings in context, and compare OLG sensitivity to NO with that of other brain cells. Lastly, the multiple interactions of NO are considered with regard to glutamate cytotoxicity, the antioxidant glutathione, mitochondrial function, and myelin architecture.
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Affiliation(s)
- Anne I Boullerne
- Department of Anesthesiology, University of Illinois at Chicago, 60612, USA.
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30
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Metea MR, Newman EA. Glial cells dilate and constrict blood vessels: a mechanism of neurovascular coupling. J Neurosci 2006; 26:2862-70. [PMID: 16540563 PMCID: PMC2270788 DOI: 10.1523/jneurosci.4048-05.2006] [Citation(s) in RCA: 439] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Neuronal activity evokes localized changes in blood flow. Although this response, termed neurovascular coupling, is widely used to monitor human brain function and diagnose pathology, the cellular mechanisms that mediate the response remain unclear. We investigated the contribution of glial cells to neurovascular coupling in the acutely isolated mammalian retina. We found that light stimulation and glial cell stimulation can both evoke dilation or constriction of arterioles. Light-evoked and glial-evoked vasodilations were blocked by inhibitors of cytochrome P450 epoxygenase, the synthetic enzyme for epoxyeicosatrienoic acids. Vasoconstrictions, in contrast, were blocked by an inhibitor of omega-hydroxylase, which synthesizes 20-hydroxyeicosatetraenoic acid. Nitric oxide influenced whether vasodilations or vasoconstrictions were produced in response to light and glial stimulation. Light-evoked vasoactivity was blocked when neuron-to-glia signaling was interrupted by a purinergic antagonist. These results indicate that glial cells contribute to neurovascular coupling and suggest that regulation of blood flow may involve both vasodilating and vasoconstricting components.
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31
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Wang S, Paton JFR, Kasparov S. The challenge of real-time measurements of nitric oxide release in the brain. Auton Neurosci 2006; 126-127:59-67. [PMID: 16624633 DOI: 10.1016/j.autneu.2006.02.026] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2005] [Revised: 02/21/2006] [Accepted: 02/27/2006] [Indexed: 01/30/2023]
Abstract
Nitric oxide (NO) acts as a signalling molecule in the brain. NO has been implicated in a variety of central functions such as learning, plasticity and neurodegeneration. It is also involved in regulation of autonomic homeostasis at different levels of neuraxis including the nucleus tractus solitarii. In spite of the ample evidence for NO-mediated signalling many aspects of its mechanism of action the brain remain unknown largely due to the difficulties of NO detection in real time coupled with its unique ability to freely cross cellular membranes. Here we give a brief overview of the currently available options for NO detection in the brain (such as electrochemistry, fluorescent indicators, electron-paramagnetic resonance) and consider some of their limitations. We conclude that it would be extremely useful to develop a highly sensitive probe for NO detection with some kind of build-in amplification which would magnify the changes triggered by NO to allow its detection within microdomains of the brain tissue in real time.
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Affiliation(s)
- S Wang
- Department of Physiology, University of Bristol, Bristol BS8 1TD, UK
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32
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Keynes R, Griffiths C, Hall C, Garthwaite J. Nitric oxide consumption through lipid peroxidation in brain cell suspensions and homogenates. Biochem J 2006; 387:685-94. [PMID: 15579136 PMCID: PMC1134998 DOI: 10.1042/bj20041431] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Mechanisms which inactivate NO (nitric oxide) are probably important in governing the physiological and pathological effects of this ubiquitous signalling molecule. Cells isolated from the cerebellum, a brain region rich in the NO signalling pathway, consume NO avidly. This property was preserved in brain homogenates and required both particulate and supernatant fractions. A purified fraction of the particulate component was rich in phospholipids, and NO consumption was inhibited by procedures that inhibited lipid peroxidation, namely a transition metal chelator, the vitamin E analogue Trolox and ascorbate oxidase. The requirement for the supernatant was accounted for by its content of ascorbate which catalyses metal-dependent lipid peroxidation. The NO-degrading activity of the homogenate was mimicked by a representative mixture of brain lipids together with ascorbate and, under these conditions, the lipids underwent peroxidation. In a suspension of cerebellar cells, there was a continuous low level of lipid peroxidation, and consumption of NO by the cells was decreased by approx. 50% by lipid-peroxidation inhibitors. Lipid peroxidation was also abolished when NO was supplied at a continuously low rate (approximately 100 nM/min), which explains why NO consumption by this process is saturable. Part of the activity remaining after the inhibition of lipid peroxidation was accounted for by contaminating red blood cells, but there was also another component whose activity was greatly enhanced when the cells were maintained under air-equilibrated conditions. A similar NO-consuming process was present in cerebellar glial cells grown in tissue culture but not in blood platelets or leucocytes, suggesting a specialized mechanism.
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Affiliation(s)
- Robert G. Keynes
- Wolfson Institute for Biomedical Research, University College London, Cruciform Building, Gower Street, London WC1E 6BT, U.K
| | - Charmaine H. Griffiths
- Wolfson Institute for Biomedical Research, University College London, Cruciform Building, Gower Street, London WC1E 6BT, U.K
| | - Catherine Hall
- Wolfson Institute for Biomedical Research, University College London, Cruciform Building, Gower Street, London WC1E 6BT, U.K
| | - John Garthwaite
- Wolfson Institute for Biomedical Research, University College London, Cruciform Building, Gower Street, London WC1E 6BT, U.K
- To whom correspondence should be addressed (email )
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Borgmann S, Radtke I, Erichsen T, Blöchl A, Heumann R, Schuhmann W. Electrochemical High-Content Screening of Nitric Oxide Release from Endothelial Cells. Chembiochem 2006; 7:662-8. [PMID: 16518864 DOI: 10.1002/cbic.200500399] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Release of nitric oxide (NO) is of high importance for regulating endothelial cell functions during vasodilatation, vascular remodeling, and angiogenesis. Thus, a direct and reliable real-time method for NO detection that takes into account time-dependent variations of the NO concentration in the complex reaction within the diffusion zone above the cells is vital for obtaining information about the role of NO in intracellular endothelial signal transduction and its impact on the surrounding cells. In this study, the time course of vascular endothelial growth factor E (VEGF-E) stimulated NO release from transformed human umbilical vein endothelial cells (T-HUVEC) was investigated by means of metalloporphyrin-based NO sensors employed in an electrochemical robotic system. The NO sensor was obtained by electrochemically induced deposition of Ni(II) tetrakis(p-nitrophenylporphyrin) on a 50-microm diameter platinum disk electrode which was integrated, together with a 25-microm diameter platinum disk, in a double-barrel electrode arrangement. The second electrode was used as a guidance sensor for the automatic and highly reproducible positioning of the NO sensor at a known distance from a layer of adherently growing cells by using z-approach curves in the negative feedback mode of scanning electrochemical microscopy (SECM). The electrochemical robotic system allows the fully automated detection of NO with high sensitivity and selectivity to be performed in real time within 96-well microtiter plates. A functional cell assay was established to allow the standardized detection of NO released upon stimulation from T-HUVEC with a sensor positioned at a known distance above the endothelial cells. The overall system was evaluated by automatic detection of NO release from T-HUVEC upon stimulation with VEGF-E after incubation with a variety of drugs that are known to act on different sites in the complex signal-transduction pathway that finally invokes NO release.
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Affiliation(s)
- Sabine Borgmann
- Analytische Chemie-Elektroanalytik & Sensorik, Ruhr-Universität Bochum, Universitätsstrasse 150, 44780 Bochum, Germany
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Rocchitta G, Migheli R, Mura MP, Esposito G, Marchetti B, Desole MS, Miele E, Serra PA. Role of endogenous melatonin in the oxidative homeostasis of the extracellular striatal compartment: a microdialysis study in PC12 cells in vitro and in the striatum of freely moving rats. J Pineal Res 2005; 39:409-18. [PMID: 16207297 DOI: 10.1111/j.1600-079x.2005.00266.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A capillary apparatus for in vitro microdialysis was used to investigate melatonin and ascorbic acid effects on dopamine (DA) autoxidation or nitric oxide (NO)-mediated oxidation in suspended PC12 cells. Following high K+ (KCl 75 mm) infusion, secreted DA underwent a partial autoxidation or peroxynitrite-mediated oxidation when the potential peroxynitrite generator 3-morpholinosydnonimine (SIN-1, 1.0 mm) was co-infused with KCl. Ascorbic acid was supplied to the medium by means of intracellular reduction of infused dehydroascorbic acid (DHAA) (5.0 mm). Melatonin (50 microm) and DHAA showed a synergistic effect in inhibiting DA autoxidation and peroxynitrite-mediated DA oxidation. Moreover, melatonin increased dialysate recovery of ascorbic acid released from PC12 cells. Endogenous melatonin was depleted in rats maintained on a 24-hr light cycle for 1 wk. In melatonin-depleted rats, baseline levels of dialysate ascorbic acid were lower than controls, while those of DA were unaffected. In these rats, intrastriatal infusion of 5.0 mm SIN-1 induced DA increases significantly lower than in controls; in addition, dialysate ascorbic acid concentrations exhibited significant decreases. Melatonin co-infusion restored SIN-1 effects on dialysate DA and antagonized SIN-1-induced ascorbic acid decreases. Melatonin-depleted rats were allowed to recover. In these rats, striatal baseline ascorbic acid, as well as SIN-1-induced increases in dialysate DA did not differ from controls. Taken together, these findings suggest that endogenous melatonin is an active component of the striatal extracellular antioxidant pool, as it maintains endogenous ascorbic acid in its reduced status and co-operates with ascorbic acid in protecting extracellular DA from exogenous NO-mediated oxidation.
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Affiliation(s)
- Gaia Rocchitta
- Department of Pharmacology, University of Sassari, Sassari, Italy
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35
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Peyrot F, Grillon C, Vergely C, Rochette L, Ducrocq C. Pharmacokinetics of 1-nitrosomelatonin and detection by EPR using iron dithiocarbamate complex in mice. Biochem J 2005; 387:473-8. [PMID: 15579132 PMCID: PMC1134976 DOI: 10.1042/bj20040828] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The N-nitroso-derivative of melatonin, NOM (1-nitrosomelatonin), which has been demonstrated to be a NO* [oxidonitrogen*] donor in buffered solutions, is a new potential drug particularly in neurological diseases. The advantage of NOM, a very lipophilic drug, is its ability to release both melatonin and NO*, an easily diffusible free radical. In order to evaluate the distribution and the pharmacokinetics of NOM, [O-methyl-3H]NOM was administered to and followed in mice. A complementary method for monitoring NOM, EPR, was performed in vitro and ex vivo with (MGD)2-Fe2+ (iron-N-methyl-D-glucamine dithiocarbamate) complex as a spin trap. The behaviour of NOM was compared with that of GSNO (S-nitrosoglutathione), a hydrophilic NO* donor. In the first minutes following [O-methyl-3H]NOM intraperitoneal injection, the radioactivity was found in organs (6% in the liver, 1% in the kidney and 0.6% in the brain), but not in the blood. In both liver and brain, the radioactivity content decreased over time with similar kinetics reflecting the diffusion and metabolism of NOM and of its metabolites. Based on the characterization and the quantification of the EPR signal in vitro with NOM or GSNO using (MGD)2-Fe2+ complex in phosphate-buffered solutions, the detection of these nitroso compounds was realized ex vivo in mouse tissue extracts. (MGD)2-Fe2+-NO was observed in the brain of NOM-treated mice in the first 10 min following injection, revealing that NOM was able to cross the blood-brain barrier, while GSNO was not.
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Affiliation(s)
- Fabienne Peyrot
- *Institut de Chimie des Substances Naturelles, CNRS, F-91198 Gif-sur-Yvette, France
| | - Catherine Grillon
- *Institut de Chimie des Substances Naturelles, CNRS, F-91198 Gif-sur-Yvette, France
| | - Catherine Vergely
- †Laboratoire de Physiopathologie et Pharmacologie Cardiovasculaires Expérimentales, Facultés de Médecine et de Pharmacie, F-21079 Dijon, France
| | - Luc Rochette
- †Laboratoire de Physiopathologie et Pharmacologie Cardiovasculaires Expérimentales, Facultés de Médecine et de Pharmacie, F-21079 Dijon, France
| | - Claire Ducrocq
- *Institut de Chimie des Substances Naturelles, CNRS, F-91198 Gif-sur-Yvette, France
- To whom correspondence should be addressed (email )
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Ghaffari A, Neil DH, Ardakani A, Road J, Ghahary A, Miller CC. A direct nitric oxide gas delivery system for bacterial and mammalian cell cultures. Nitric Oxide 2005; 12:129-40. [PMID: 15797841 DOI: 10.1016/j.niox.2005.01.006] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2004] [Revised: 12/01/2004] [Accepted: 01/23/2005] [Indexed: 10/25/2022]
Abstract
Nitric oxide (NO) is the smallest known gaseous signaling molecule released by mammalian and plant cells. To investigate the pathophysiologic role of exogenous NO gas (gNO) in bacterial and mammalian cell cultures, a validated in vitro delivery method is required. The system should be able to deliver gNO directly to bacterial and/or cell cultures in a continuous, predictable, and reproducible manner over a long period of time (days). To accomplish this, a gas delivery system was designed to provide optimal growth conditions for bacteria and/or mammalian cells. Parameters for cell exposure, such as concentration of gNO, nitrogen dioxide (NO(2)), oxygen (O(2)), temperature, and relative humidity (RH) were continuously monitored and evaluated. Uptake of gNO into various media was monitored by measuring the nitrite concentration using the Griess reagent technique. A selection of standard growth media [saline, tryptic soy broth (TSB), Middlebrook 7H9 (MB 7H9), and Dulbecco's modified Eagle's medium (DMEM)] exposed to various concentrations of gNO revealed a steady and consistent transfer of gNO into the aqueous phase over a 48-h period. Validation of optimal growth conditions within the device, as compared to a conventional incubator, were accomplished by growing and observing viability of Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and human fibroblast cultures in the absence of gNO. These results indicate that an optimal growth environment for the above tested cells was accomplished inside the proposed delivery system. Dose-dependent toxicological data revealed a significant bacteriostatic effect on P. aeruginosa and S. aureus with continuous exposure to 80 ppm gNO. No toxic effects were observed on dermal fibroblast proliferation at concentrations up to 400 ppm gNO for 48 h. In conclusion, the designed gNO exposure system is capable of supporting cellular viability for a representative range of prokaryote and eukaryotic cells. The exposure system is also capable of obtaining toxicological data. Therefore, the proposed device can be utilized to continuously expose cells to various levels of gNO for up to 72 h to study the in vitro effects of gNO therapy.
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Affiliation(s)
- A Ghaffari
- Department of Surgery, Wound Healing Research Group, University of Alberta, Edmonton, Alta., Canada.
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37
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Crane MS, Rossi AG, Megson IL. A potential role for extracellular nitric oxide generation in cGMP-independent inhibition of human platelet aggregation: biochemical and pharmacological considerations. Br J Pharmacol 2005; 144:849-59. [PMID: 15685209 PMCID: PMC1576067 DOI: 10.1038/sj.bjp.0706110] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
1. Nitric oxide (NO) is a potent inhibitor of platelet activation, that inhibits the agonist-induced increase in cytosolic Ca2+ concentration through both cGMP-dependent and independent pathways. However, the NO-related (NOx) species responsible for cGMP-independent signalling in platelets is unclear. We tested the hypothesis that extracellular NO, but not NO+ or peroxynitrite, generated in the extracellular compartment is responsible for cGMP-independent inhibition of platelet activation via inhibition of Ca2+ signalling. 2. Concentration-response curves for diethylamine diazeniumdiolate (DEA/NO; a spontaneous NO generator), S-nitroso-N-valerylpenicillamine (SNVP; an S-nitrosothiol) and 3-morpholinosydnonomine (SIN-1; a peroxynitrite generator) were generated in platelet-rich plasma (PRP) and washed platelets (WP) in the presence and absence of a supramaximal concentration of the soluble guanylate cyclase inhibitor, ODQ (20 microM). All three NOx donors displayed cGMP-independent inhibition of platelet aggregation in PRP, but only DEA/NO exhibited cGMP-independent inhibition of aggregation in WP. 3. Analysis of NO generation using an isolated NO-electrode revealed that cGMP-independent effects coincided with the generation of substantial levels of extracellular NO (>40 nM) from the NOx donors. 4. Reconstitution of WP with plasma factors indicated that the copper-containing plasma protein, caeruloplasmin (CP), catalysed the release of NO from SNVP, while Cu/Zn superoxide dismutase (SOD) unmasked NO generated from SIN-1. The increased generation of extracellular NO correlated with a switch to cGMP-independent effects with both NOx donors. 5. Analysis of Fura-2 loaded WP revealed that only DEA/NO inhibited Ca2+ signalling in platelets via a cGMP-independent mechanism. However, preincubation of SNVP and SIN-1 with CP and SOD, respectively, induced cGMP-independent inhibition of intraplatelet Ca2+ trafficking by the NOx donors. 6. Taken together, our data suggest that extracellular NO (>40 nM) is required for cGMP-independent inhibition of platelet activation. Plasma constituents may play an important pharmacological role in activating cGMP-independent signalling by S-nitrosothiols or peroxynitrite generators.
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Affiliation(s)
- Michael S Crane
- Centre for Cardiovascular Science, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh EH8 9XD
| | - Adriano G Rossi
- Centre for Inflammation Research, University of Edinburgh, George Square, Edinburgh EH8 9XD
| | - Ian L Megson
- Centre for Cardiovascular Science, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh EH8 9XD
- Author for correspondence:
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Heuser M, Kopun M, Rittgen W, Granzow C. Cytotoxicity determination without photochemical artifacts. Cancer Lett 2005; 223:57-66. [PMID: 15890237 DOI: 10.1016/j.canlet.2004.10.031] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2004] [Revised: 10/10/2004] [Accepted: 10/13/2004] [Indexed: 11/20/2022]
Abstract
A study was performed to improve cytotoxicity determinations by eliminating flavin-mediated photosensitization from tests with KB cells, NCI-H69 cells, P-glycoprotein expressing KBC5-8 cells, MRP1-expressing H69AR cells, and A240286S human lung adenocarcinoma cells. Growth inhibition by cis-platin, doxorubicin, etoposide, gemcitabine, taxol, vincristine, vinblastine, and vinorelbine was determined under flavin-protecting conditions using flavin-free culture media with fetal bovine serum as the only source of flavins. As compared to conventional tests, the IC50 values determined under flavin-protecting conditions reflected increased apparent drug cytotoxicities, and were flawlessly reproducible. Flavin-mediated photosensitization should, therefore, be strictly eliminated from in vitro experiments involving cytotoxic and other drugs.
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Affiliation(s)
- Michael Heuser
- Abteilung Molekulare Toxikologie (E080), Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 280, D-69120 Heidelberg, Germany
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Choi BH, Ha KC, Park JA, Jung YJ, Kim JC, Lee GI, Choi HS, Kang YJ, Chae SW, Kwak YG. Regional differences of superoxide dismutase activity enhance the superoxide–induced electrical heterogeneity in rabbit hearts. Basic Res Cardiol 2005; 100:355-64. [PMID: 15870956 DOI: 10.1007/s00395-005-0531-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2004] [Revised: 03/14/2005] [Accepted: 04/05/2005] [Indexed: 11/28/2022]
Abstract
During myocardial ischemia and the subsequent reperfusion, free radicals are important intermediates of the cellular damage and rhythm disturbances. We examined the effects of superoxide radicals or hydrogen peroxide (H(2)O(2)) on the action potentials in isolated rabbit Purkinje fibers, atrial muscle and ventricular muscle. Reactive oxygen species (ROS) donors such as adriamycin, xanthine/xanthine oxidase and menadione induced prolongation of APD(90) in Purkinje fibers. Menadione (30 microM), the most specific superoxide radical donor, prolonged the action potential duration at 90% repolarization (APD(90)) by 17% in Purkinje fibers, whereas it shortened the APD by 57% in ventricular muscle, and it did not affect the atrial APD. All these menadione-induced effects were completely blocked by 2,2,6,6-tetramethyl- 1-peperadinyloxy, a superoxide radical scavenger. Superoxide dismutase (SOD) activity was lowest in Purkinje fibers, it was moderate in atrial muscle and highest in ventricular muscle. H(2)O(2) shortened the APDs of all three cardiac tissues in a concentration-dependent manner. These results suggest that the different electrical responses to O(2) ([Symbol: see text]-) in different cardiac regions may result from the regional differences in the SOD activity, thereby enhancing the regional electrical heterogeneity.
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Affiliation(s)
- B H Choi
- Department of Pharmacology, Institute of Cardiovascular Research, Chonbuk National University, Medical School, Chonju 560-182, Republic of Korea
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Nalwaya N, Deen WM. Nitric Oxide, Oxygen, and Superoxide Formation and Consumption in Macrophage Cultures. Chem Res Toxicol 2005; 18:486-93. [PMID: 15777088 DOI: 10.1021/tx049879c] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
To examine the potential for generating toxic nitrogen oxides during the immune response, rates of formation and consumption of NO, O2, and O2- were measured in murine macrophage-like RAW264.7 cells. Cellular kinetic parameters for NO and O2 were obtained by monitoring their time-dependent concentrations in a closed chamber, and net cellular synthesis of O2- was quantified from ferricytochrome c reduction in cultures where NO synthesis was inhibited. Also measured was the photosensitive generation of O2- in the culture media. Unactivated cells (without NO synthesis) had an O2 consumption rate of 32+/-3 pmol s-1 (10(6) cells)-1, typical of mammalian cells. Also typical was that adding NO rapidly and reversibly inhibited respiration. Activated cells synthesized NO at a rate of 4.9+/-0.6 pmol s-1 (10(6) cells)-1. When NO synthesis was inhibited, they consumed three times as much O2 as unactivated cells [108+/-17 pmol s-1 (10(6) cells)-1]; however, O2 consumption of activated cells exposed to 1 microM NO was calculated to be comparable to that of NO-free unactivated cells. Rates of intracellular NO consumption were small, implying that enzymatic consumption does little to limit net NO synthesis by macrophages. Accounting for O2- generation in the culture media resulted in net rates of cellular O2- synthesis smaller than previously reported; the rate was 6% of NO synthesis in activated cells and was undetectable in unactivated cells.
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Affiliation(s)
- Nitesh Nalwaya
- Department of Chemical Engineering and Biological Engineering Division, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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41
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Duport S, Garthwaite J. Pathological consequences of inducible nitric oxide synthase expression in hippocampal slice cultures. Neuroscience 2005; 135:1155-66. [PMID: 16165295 DOI: 10.1016/j.neuroscience.2005.06.035] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2005] [Revised: 05/16/2005] [Accepted: 06/09/2005] [Indexed: 12/31/2022]
Abstract
The generation of toxic concentrations of nitric oxide by the inducible nitric oxide synthase expressed in microglia and other brain cell types is frequently invoked as a causative factor in neurodegeneration. Experiments were carried out on slice cultures of rat hippocampus to test this hypothesis. Exposure of the slices to bacterial lipopolysaccharide plus interferon-gamma led to a time-dependent expression of functional inducible nitric oxide synthase that was found only in microglia. Microglial activation by other means, such as physical damage, was not associated with inducible nitric oxide synthase expression. Damage and cell death in slices expressing inducible nitric oxide synthase was evaluated over a period of 6 days, but none was found. Consistent with this result, cGMP measurements indicated that the average local nitric oxide concentration remained in the low nanomolar range. When the microglial population was expanded to a density three-fold above normal by applying granulocyte-macrophage colony stimulating factor, however, lipopolysaccharide plus interferon-gamma provoked neurodegeneration that could be blocked by an inducible nitric oxide synthase inhibitor. The associated nitric oxide concentration in the slices was saturating for guanylyl cyclase-coupled nitric oxide receptors, signifying at least 10 nM. It is concluded that inducible nitric oxide synthase is expressed in microglia only in response to specific stimuli involving the innate immune system, and that the resulting level of nitric oxide in intact brain tissue is normally too low to inflict damage directly. Quantities of nitric oxide sufficient to contribute directly or indirectly to pathology could be produced should the density of microglia become high enough, although caution must be exercised in extrapolating this finding to the human brain in vivo.
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Affiliation(s)
- S Duport
- Wolfson Institute for Biomedical Research, University College London, Gower Street, London WC1E 6BT, UK
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42
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Rocchitta G, Migheli R, Mura MP, Esposito G, Desole MS, Miele E, Miele M, Serra PA. Signalling pathways in the nitric oxide donor-induced dopamine release in the striatum of freely moving rats: evidence that exogenous nitric oxide promotes Ca2+ entry through store-operated channels. Brain Res 2004; 1023:243-52. [PMID: 15374750 DOI: 10.1016/j.brainres.2004.07.040] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/14/2004] [Indexed: 10/26/2022]
Abstract
We showed previously, using in vitro microdialysis, that the activation of the soluble guanylate cyclase (sGC)/cyclic GMP pathway was the underlying mechanism of the extracellular Ca(2+)-dependent effects of exogenous NO on dopamine (DA) secretion from PC12 cells. In this study, the co-infusion of the sGC inhibitor 1H-[1,2,4]oxadiazolo[4,3] quinoxalin-1-one (ODQ) failed to affect the NO donor 3-morpholinosydnonimine (SIN-1, 5.0 mM)-induced DA increase (sevenfold baseline) in dialysates from the striatum of freely moving rats. Ca(2+) omission from the perfusion fluid abolished baseline DA release but did not affect SIN-1-induced DA increases. The reintroduction of Ca(2+) in the perfusion fluid restored the baseline dialysate DA; however, when Ca(2+) reintroduction was associated with the infusion of either SIN-1 or the NO-donor S-nitrosoglutathione (SNOG), a sustained DA overflow was observed. DA overflow was selectively inhibited by the co-infusion of the store-operated channel blocker 2-aminoethoxydiphenyl borate. The chelation of intracellular Ca(2+) by co-infusing 1,2-bis (o-amino-phenoxy)ethane-N,N,N',N'-tetraacetic acid tetra (acetoxymethyl) ester (BAPTA-AM, 0.2 mM) greatly potentiated both SIN-1- and SNOG-induced increases in dialysate DA. BAPTA-AM-induced potentiation was inhibited by Ca(2+) omission. We conclude that the sGC/cyclic GMP pathway is not involved in the extracellular Ca(2+)-independent exogenous NO-induced striatal DA release; however, when intracellular Ca(2+) is either depleted (by Ca(2+) omission) or chelated (by BAPTA-AM co-infusion), exogenous NO does promote Ca(2+) entry, most likely through store-operated channels, with a consequent further increase in DA release.
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Affiliation(s)
- Gaia Rocchitta
- Department of Pharmacology, University of Sassari, viale S.Pietro 43B, 07100 Sassari, Italy
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43
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Keynes RG, Duport S, Garthwaite J. Hippocampal neurons in organotypic slice culture are highly resistant to damage by endogenous and exogenous nitric oxide. Eur J Neurosci 2004; 19:1163-73. [PMID: 15016075 DOI: 10.1111/j.1460-9568.2004.03217.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Nitric oxide (NO) has been proposed to mediate neurodegeneration arising from NMDA receptor activity, but the issue remains controversial. The hypothesis was re-examined using organotypic slice cultures of rat hippocampus, with steps being taken to avoid known artefacts. The NO-cGMP signalling pathway was well preserved in such cultures. Brief exposure to NMDA resulted in a concentration-dependent delayed neuronal death that could be nullified by administration of the NMDA antagonist MK801 (10 microm) given postexposure. Two inhibitors of NO synthesis failed to protect the slices, despite fully blocking NMDA-induced cGMP accumulation. By comparing NMDA-induced cGMP accumulation with that produced by an NO donor, toxic NMDA concentrations were estimated to produce only physiological NO concentrations (2 nm). In studies of the vulnerability of the slices to exogenous NO, it was found that continuous exposure to up to 4.5 microm NO failed to affect ATP levels (measured after 6 h) or cause damage during 24 h, whereas treatment with the respiratory inhibitors myxothiazol or cyanide caused ATP depletion and complete cell death within 24 h. An NO concentration of 10 microm was required for ATP depletion and cell death, presumably through respiratory inhibition. It is concluded that sustained activity of neuronal NO synthase in intact hippocampal tissue can generate only low nanomolar NO concentrations, which are unlikely to be toxic. At the same time, the tissue is remarkably resistant to exogenous NO at up to 1000-fold higher concentrations. Together, the results seriously question the proposed role of NO in NMDA receptor-mediated excitotoxicity.
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Affiliation(s)
- Robert G Keynes
- Wolfson Institute for Biomedical Research, University College London, Cruciform Building, Gower Street, London WC1E 6BT, UK
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44
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Serra PA, Migheli R, Rocchitta G, Taras MG, Mura MP, Delogu MR, Esposito G, Desole MS, Miele E, Miele M. Role of the nitric oxide/cyclic GMP pathway and ascorbic acid in 3-morpholinosydnonimine (SIN-1)-induced increases in dopamine secretion from PC12 cells. A microdialysis in vitro study. Neurosci Lett 2003; 353:5-8. [PMID: 14642424 DOI: 10.1016/j.neulet.2003.07.022] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
We showed previously, using in vitro microdialysis, that activation of the nitric oxide (NO)/cyclic GMP pathway was the underlying mechanism of exogenous NO-induced dopamine (DA) secretion from PC12 cells. In this study, infusion of the potential peroxynitrite generator 3-morpholinosydnonimine (SIN-1, 1.0 mM for 60 min) induced a long-lasting decrease in dialysate DA+3-methoxytyramine (3-MT) in dialysates from PC12 cell suspensions. Ascorbic acid (0.2 mM) co-infusion allowed SIN-1 to increase dialysate DA+3-MT. SIN-1+ascorbic acid effects were abolished by Ca(2+) omission. Infusion of high K(+) (75 mM) induced a 2.5-fold increase in dialysate DA+3-MT. The increase was inhibited by SIN-1 co-infusion. Conversely, co-infusion of ascorbic acid (0.2 mM) with SIN-1+high K(+) resulted in a 3.5 fold increase in dialysate DA+3-MT. The L-type Ca(2+) channel inhibitor nifedipine selectively inhibited the DA+3-MT increase pertaining to high K(+), while the soluble guanylate cyclase (sGC) inhibitor 1H-[1,2,4]-oxadiazolo[4,3]quinoxalin-1-one selectively inhibited the increase pertaining to SIN-1 effects. These results suggest that activation of the NO/sGC/cyclic GMP pathway is the underlying mechanism of extracellular Ca(2+)-dependent effects of SIN-1 on DA secretion from PC12 cells. Extracellular Ca(2+) entry occurs through nifedipine-insensitive channels. Ascorbic acid is a key determinant in modulating the distinct profiles of SIN-1 effects.
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Affiliation(s)
- Pier Andrea Serra
- Department of Pharmacology, University of Sassari, viale S. Pietro 43B, 07100 Sassari, Italy
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