1
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Zaytseva AK, Kulichik OE, Kostareva AA, Zhorov BS. Biophysical mechanisms of myocardium sodium channelopathies. Pflugers Arch 2024; 476:735-753. [PMID: 38424322 DOI: 10.1007/s00424-024-02930-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 02/15/2024] [Accepted: 02/16/2024] [Indexed: 03/02/2024]
Abstract
Genetic variants of gene SCN5A encoding the alpha-subunit of cardiac voltage-gated sodium channel Nav1.5 are associated with various diseases, including long QT syndrome (LQT3), Brugada syndrome (BrS1), and progressive cardiac conduction disease (PCCD). In the last decades, the great progress in understanding molecular and biophysical mechanisms of these diseases has been achieved. The LQT3 syndrome is associated with gain-of-function of sodium channels Nav1.5 due to impaired inactivation, enhanced activation, accelerated recovery from inactivation or the late current appearance. In contrast, BrS1 and PCCD are associated with the Nav1.5 loss-of-function, which in electrophysiological experiments can be manifested as reduced current density, enhanced fast or slow inactivation, impaired activation, or decelerated recovery from inactivation. Genetic variants associated with congenital arrhythmias can also disturb interactions of the Nav1.5 channel with different proteins or drugs and cause unexpected reactions to drug administration. Furthermore, mutations can affect post-translational modifications of the channels and their sensitivity to pH and temperature. Here we briefly review the current knowledge on biophysical mechanisms of LQT3, BrS1 and PCCD. We focus on limitations of studies that use heterologous expression systems and induced pluripotent stem cells (iPSC) derived cardiac myocytes and summarize our understanding of genotype-phenotype relations of SCN5A mutations.
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Affiliation(s)
- Anastasia K Zaytseva
- Almazov National Medical Research Centre, St. Petersburg, Russia.
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg, Russia.
| | - Olga E Kulichik
- Almazov National Medical Research Centre, St. Petersburg, Russia
| | | | - Boris S Zhorov
- Almazov National Medical Research Centre, St. Petersburg, Russia
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg, Russia
- McMaster University, Hamilton, Canada
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2
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Labau JIR, Alsaloum M, Estacion M, Tanaka B, Dib-Hajj FB, Lauria G, Smeets HJM, Faber CG, Dib-Hajj S, Waxman SG. Lacosamide Inhibition of Na V1.7 Channels Depends on its Interaction With the Voltage Sensor Domain and the Channel Pore. Front Pharmacol 2022; 12:791740. [PMID: 34992539 PMCID: PMC8724789 DOI: 10.3389/fphar.2021.791740] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Accepted: 12/02/2021] [Indexed: 12/14/2022] Open
Abstract
Lacosamide, developed as an anti-epileptic drug, has been used for the treatment of pain. Unlike typical anticonvulsants and local anesthetics which enhance fast-inactivation and bind within the pore of sodium channels, lacosamide enhances slow-inactivation of these channels, suggesting different binding mechanisms and mode of action. It has been reported that lacosamide's effect on NaV1.5 is sensitive to a mutation in the local anesthetic binding site, and that it binds with slow kinetics to the fast-inactivated state of NaV1.7. We recently showed that the NaV1.7-W1538R mutation in the voltage-sensing domain 4 completely abolishes NaV1.7 inhibition by clinically-achievable concentration of lacosamide. Our molecular docking analysis suggests a role for W1538 and pore residues as high affinity binding sites for lacosamide. Aryl sulfonamide sodium channel blockers are also sensitive to substitutions of the W1538 residue but not of pore residues. To elucidate the mechanism by which lacosamide exerts its effects, we used voltage-clamp recordings and show that lacosamide requires an intact local anesthetic binding site to inhibit NaV1.7 channels. Additionally, the W1538R mutation does not abrogate local anesthetic lidocaine-induced blockade. We also show that the naturally occurring arginine in NaV1.3 (NaV1.3-R1560), which corresponds to NaV1.7-W1538R, is not sufficient to explain the resistance of NaV1.3 to clinically-relevant concentrations of lacosamide. However, the NaV1.7-W1538R mutation conferred sensitivity to the NaV1.3-selective aryl-sulfonamide blocker ICA-121431. Together, the W1538 residue and an intact local anesthetic site are required for lacosamide's block of NaV1.7 at a clinically-achievable concentration. Moreover, the contribution of W1538 to lacosamide inhibitory effects appears to be isoform-specific.
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Affiliation(s)
- Julie I R Labau
- Department of Neurology, Yale University School of Medicine, New Haven, CT, United States.,Center for Neuroscience and Regeneration Research, Yale University, West Haven, CT, United States.,Rehabilitation Research Center, Veteran Affairs Connecticut Healthcare System, West Haven, CT, United States.,Department of Toxicogenomics, Clinical Genomics, Maastricht University Medical Centre+, Maastricht, Netherlands.,School of Mental Health and Neuroscience, Maastricht University, Maastricht, Netherlands
| | - Matthew Alsaloum
- Department of Neurology, Yale University School of Medicine, New Haven, CT, United States.,Center for Neuroscience and Regeneration Research, Yale University, West Haven, CT, United States.,Rehabilitation Research Center, Veteran Affairs Connecticut Healthcare System, West Haven, CT, United States.,Yale Medical Scientist Training Program, Yale School of Medicine, New Haven, CT, United States.,Interdepartmental Neuroscience Program, Yale School of Medicine, New Haven, CT, United States
| | - Mark Estacion
- Department of Neurology, Yale University School of Medicine, New Haven, CT, United States.,Center for Neuroscience and Regeneration Research, Yale University, West Haven, CT, United States.,Rehabilitation Research Center, Veteran Affairs Connecticut Healthcare System, West Haven, CT, United States
| | - Brian Tanaka
- Department of Neurology, Yale University School of Medicine, New Haven, CT, United States.,Center for Neuroscience and Regeneration Research, Yale University, West Haven, CT, United States.,Rehabilitation Research Center, Veteran Affairs Connecticut Healthcare System, West Haven, CT, United States
| | - Fadia B Dib-Hajj
- Department of Neurology, Yale University School of Medicine, New Haven, CT, United States.,Center for Neuroscience and Regeneration Research, Yale University, West Haven, CT, United States.,Rehabilitation Research Center, Veteran Affairs Connecticut Healthcare System, West Haven, CT, United States
| | - Giuseppe Lauria
- Neuroalgology Unit, IRCCS Foundation, "Carlo Besta" Neurological Institute, Milan, Italy.,Department of Medical Biotechnology and Translational Medicine, University of Milan, Milan, Italy
| | - Hubert J M Smeets
- Department of Toxicogenomics, Clinical Genomics, Maastricht University Medical Centre+, Maastricht, Netherlands.,School of Mental Health and Neuroscience, Maastricht University, Maastricht, Netherlands
| | - Catharina G Faber
- Department of Neurology, School of Mental Health and Neuroscience, Maastricht University Medical Center, Maastricht, Netherlands
| | - Sulayman Dib-Hajj
- Department of Neurology, Yale University School of Medicine, New Haven, CT, United States.,Center for Neuroscience and Regeneration Research, Yale University, West Haven, CT, United States.,Rehabilitation Research Center, Veteran Affairs Connecticut Healthcare System, West Haven, CT, United States
| | - Stephen G Waxman
- Department of Neurology, Yale University School of Medicine, New Haven, CT, United States.,Center for Neuroscience and Regeneration Research, Yale University, West Haven, CT, United States.,Rehabilitation Research Center, Veteran Affairs Connecticut Healthcare System, West Haven, CT, United States
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3
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Arora M, Choudhary S, Singh PK, Sapra B, Silakari O. Structural investigation on the selective COX-2 inhibitors mediated cardiotoxicity: A review. Life Sci 2020; 251:117631. [PMID: 32251635 DOI: 10.1016/j.lfs.2020.117631] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2019] [Accepted: 03/31/2020] [Indexed: 01/30/2023]
Abstract
Initially, the selective COX-2 inhibitors were developed as safer alternatives to the conventional NSAIDs, but later on, most of them were withdrawn from the market due to the risk of heart attack and stroke. Celecoxib, the first selective COX-2 inhibitor, was approved by the Food and Drug Administration (FDA) in December 1998 and was taken back from the market in 2004. Since then, many coxibs have been discontinued one by one due to adverse cardiovascular events. United States (US), Australian and European authorities related to Therapeutic Goods Administration (TGA) implemented the requirements to carry the "Black box" warning on the labels of COX-2 drugs highlighting the risks of serious cardiovascular events. These facts encouraged the researchers to explore them well and find out the biochemical basis behind the cardiotoxicity. From the last few decades, the molecular mechanisms behind the coxibs have regained the attention, especially the specific structural features of the selective COX-2 inhibitors that are associated with cardiotoxicity. This review discusses the key structural features of the selective COX-2 inhibitors and underlying mechanisms that are responsible for the cardiotoxicity. This report also unfolds different strategies that have been reported in the last 10 years to combat the problem of selective COX-2 inhibitors mediated cardiotoxicity.
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Affiliation(s)
- Mohit Arora
- Molecular Modelling Lab (MML), Department of Pharmaceutical Sciences and Drug Research, Punjabi University, Patiala, Punjab 147002, India
| | - Shalki Choudhary
- Molecular Modelling Lab (MML), Department of Pharmaceutical Sciences and Drug Research, Punjabi University, Patiala, Punjab 147002, India
| | - Pankaj Kumar Singh
- Department of Chemistry and Pharmacy, University of Sassari, 07100 Sassari, Italy
| | - Bharti Sapra
- Molecular Modelling Lab (MML), Department of Pharmaceutical Sciences and Drug Research, Punjabi University, Patiala, Punjab 147002, India
| | - Om Silakari
- Molecular Modelling Lab (MML), Department of Pharmaceutical Sciences and Drug Research, Punjabi University, Patiala, Punjab 147002, India.
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4
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Jiang D, Shi H, Tonggu L, Gamal El-Din TM, Lenaeus MJ, Zhao Y, Yoshioka C, Zheng N, Catterall WA. Structure of the Cardiac Sodium Channel. Cell 2019; 180:122-134.e10. [PMID: 31866066 DOI: 10.1016/j.cell.2019.11.041] [Citation(s) in RCA: 180] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 11/18/2019] [Accepted: 11/27/2019] [Indexed: 12/19/2022]
Abstract
Voltage-gated sodium channel Nav1.5 generates cardiac action potentials and initiates the heartbeat. Here, we report structures of NaV1.5 at 3.2-3.5 Å resolution. NaV1.5 is distinguished from other sodium channels by a unique glycosyl moiety and loss of disulfide-bonding capability at the NaVβ subunit-interaction sites. The antiarrhythmic drug flecainide specifically targets the central cavity of the pore. The voltage sensors are partially activated, and the fast-inactivation gate is partially closed. Activation of the voltage sensor of Domain III allows binding of the isoleucine-phenylalanine-methionine (IFM) motif to the inactivation-gate receptor. Asp and Ala, in the selectivity motif DEKA, line the walls of the ion-selectivity filter, whereas Glu and Lys are in positions to accept and release Na+ ions via a charge-delocalization network. Arrhythmia mutation sites undergo large translocations during gating, providing a potential mechanism for pathogenic effects. Our results provide detailed insights into Nav1.5 structure, pharmacology, activation, inactivation, ion selectivity, and arrhythmias.
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Affiliation(s)
- Daohua Jiang
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA
| | - Hui Shi
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA; Howard Hughes Medical Institute, University of Washington, Seattle, WA 98195, USA
| | - Lige Tonggu
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA
| | | | - Michael J Lenaeus
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA; Division of General Internal Medicine, Department of Medicine, University of Washington, Seattle, WA 98195, USA
| | - Yan Zhao
- Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Craig Yoshioka
- Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Ning Zheng
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA; Howard Hughes Medical Institute, University of Washington, Seattle, WA 98195, USA.
| | - William A Catterall
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA.
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5
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Abstract
Although cardiac sodium channel blocking drugs can exert antiarrhythmic actions, they can also provoke life-threatening arrhythmias through a variety of mechanisms. This review addresses the way in which drugs interact with the channel, and how these effects translate to clinical beneficial or detrimental effects. A further understanding of the details of channel function and of drug-channel interactions may lead to the development of safer and more effective antiarrhythmic therapies.
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Affiliation(s)
- Dan M Roden
- Departments of Medicine and Pharmacology, Vanderbilt University School of Medicine, Nashville, TN 37232
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6
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Frolov RV, Singh S. Celecoxib and ion channels: a story of unexpected discoveries. Eur J Pharmacol 2014; 730:61-71. [PMID: 24630832 DOI: 10.1016/j.ejphar.2014.02.032] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2013] [Revised: 01/28/2014] [Accepted: 02/18/2014] [Indexed: 10/25/2022]
Abstract
Celecoxib (Celebrex), a highly popular selective inhibitor of cyclooxygenase-2, can modulate ion channels and alter functioning of neurons and myocytes at clinically relevant concentrations independently of cyclooxygenase inhibition. In experimental systems varying from Drosophila to primary mammalian and human cell lines, celecoxib inhibits many voltage-activated Na(+), Ca(2+), and K(+) channels, including NaV1.5, L- and T-type Ca(2+) channels, KV1.5, KV2.1, KV4.3, KV7.1, KV11.1 (hERG), while stimulating other K(+) channels-KV7.2-5 and, possibly, KV11.1 (hERG) channels under certain conditions. In this review, we summarize the information currently available on the effects of celecoxib on ion channels, examine mechanistic aspects of drug action and the concomitant changes at the cellular and organ levels, and discuss these findings in the therapeutic context.
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Affiliation(s)
- Roman V Frolov
- Department of Physical Sciences, Division of Biophysics, University of Oulu, PO Box 3000, 90014 Oulun Yliopisto, Finland.
| | - Satpal Singh
- Department of Pharmacology and Toxicology, State University of New York at Buffalo, Buffalo, NY 14214, USA
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7
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Ashraf MN, Gavrilovici C, Shah SUA, Shaheen F, Choudhary MI, Rahman AU, Fahnestock M, Simjee SU, Poulter MO. A novel anticonvulsant modulates voltage-gated sodium channel inactivation and prevents kindling-induced seizures. J Neurochem 2013; 126:651-61. [PMID: 23796540 DOI: 10.1111/jnc.12352] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Revised: 06/06/2013] [Accepted: 06/10/2013] [Indexed: 02/07/2023]
Abstract
Here, we explore the mechanism of action of isoxylitone (ISOX), a molecule discovered in the plant Delphinium denudatum, which has been shown to have anticonvulsant properties. Patch-clamp electrophysiology assayed the activity of ISOX on voltage-gated sodium channels (VGSCs) in both cultured neurons and brain slices isolated from controls and rats with experimental epilepsy(kindling model). Quantitative transcription polymerase chain reaction (qRT-PCR) (QPCR) assessed brain-derived neurotrophic factor (BDNF) mRNA expression in kindled rats, and kindled rats treated with ISOX. ISOX suppressed sodium current (I(Na)) showing an IC50 value of 185 nM in cultured neurons. ISOX significantly slowed the recovery from inactivation (ISOX τ = 18.7 ms; Control τ = 9.4 ms; p < 0.001). ISOX also enhanced the development of inactivation by shifting the Boltzmann curve to more hyperpolarized potentials by -11.2 mV (p < 0.05). In naive and electrically kindled cortical neurons, the IC50 for sodium current block was identical to that found in cultured neurons. ISOX prevented kindled stage 5 seizures and decreased the enhanced BDNF mRNA expression that is normally associated with kindling (p < 0.05). Overall, our data show that ISOX is a potent inhibitor of VGSCs that stabilizes steady-state inactivation while slowing recovery and enhancing inactivation development. Like many other sodium channel blocker anti-epileptic drugs, the suppression of BDNF mRNA expression that usually occurs with kindling is likely a secondary outcome that nevertheless would suppress epileptogenesis. These data show a new class of anti-seizure compound that inhibits sodium channel function and prevents the development of epileptic seizures.
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Affiliation(s)
- Muhammad N Ashraf
- H.E.J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Karachi, Pakistan
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8
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Frolov RV, Ignatova II, Singh S. Inhibition of HERG potassium channels by celecoxib and its mechanism. PLoS One 2011; 6:e26344. [PMID: 22039467 PMCID: PMC3200315 DOI: 10.1371/journal.pone.0026344] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2011] [Accepted: 09/25/2011] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND Celecoxib (Celebrex), a widely prescribed selective inhibitor of cyclooxygenase-2, can modulate ion channels independently of cyclooxygenase inhibition. Clinically relevant concentrations of celecoxib can affect ionic currents and alter functioning of neurons and myocytes. In particular, inhibition of Kv2.1 channels by celecoxib leads to arrhythmic beating of Drosophila heart and of rat heart cells in culture. However, the spectrum of ion channels involved in human cardiac excitability differs from that in animal models, including mammalian models, making it difficult to evaluate the relevance of these observations to humans. Our aim was to examine the effects of celecoxib on hERG and other human channels critically involved in regulating human cardiac rhythm, and to explore the mechanisms of any observed effect on the hERG channels. METHODS AND RESULTS Celecoxib inhibited the hERG, SCN5A, KCNQ1 and KCNQ1/MinK channels expressed in HEK-293 cells with IC(50)s of 6.0 µM, 7.5 µM, 3.5 µM and 3.7 µM respectively, and the KCND3/KChiP2 channels expressed in CHO cells with an IC(50) of 10.6 µM. Analysis of celecoxib's effects on hERG channels suggested gating modification as the mechanism of drug action. CONCLUSIONS The above channels play a significant role in drug-induced long QT syndrome (LQTS) and short QT syndrome (SQTS). Regulatory guidelines require that all new drugs under development be tested for effects on the hERG channel prior to first administration in humans. Our observations raise the question of celecoxib's potential to induce cardiac arrhythmias or other channel related adverse effects, and make a case for examining such possibilities.
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Affiliation(s)
- Roman V. Frolov
- Department of Pharmacology and Toxicology, State University of New York, Buffalo, New York, United States of America
- Division of Biophysics, Department of Physical Sciences, University of Oulu, Oulun Yliopisto, Finland
| | - Irina I. Ignatova
- Department of Pharmacology and Toxicology, State University of New York, Buffalo, New York, United States of America
- Division of Biophysics, Department of Physical Sciences, University of Oulu, Oulun Yliopisto, Finland
| | - Satpal Singh
- Department of Pharmacology and Toxicology, State University of New York, Buffalo, New York, United States of America
- * E-mail:
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Jeong EM, Liu M, Sturdy M, Gao G, Varghese ST, Sovari AA, Dudley SC. Metabolic stress, reactive oxygen species, and arrhythmia. J Mol Cell Cardiol 2011; 52:454-63. [PMID: 21978629 DOI: 10.1016/j.yjmcc.2011.09.018] [Citation(s) in RCA: 162] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2011] [Revised: 08/20/2011] [Accepted: 09/19/2011] [Indexed: 02/07/2023]
Abstract
Cardiac arrhythmias can cause sudden cardiac death (SCD) and add to the current heart failure (HF) health crisis. Nevertheless, the pathological processes underlying arrhythmias are unclear. Arrhythmic conditions are associated with systemic and cardiac oxidative stress caused by reactive oxygen species (ROS). In excitable cardiac cells, ROS regulate both cellular metabolism and ion homeostasis. Increasing evidence suggests that elevated cellular ROS can cause alterations of the cardiac sodium channel (Na(v)1.5), abnormal Ca(2+) handling, changes of mitochondrial function, and gap junction remodeling, leading to arrhythmogenesis. This review summarizes our knowledge of the mechanisms by which ROS may cause arrhythmias and discusses potential therapeutic strategies to prevent arrhythmias by targeting ROS and its consequences. This article is part of a Special Issue entitled "Local Signaling in Myocytes".
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Affiliation(s)
- Euy-Myoung Jeong
- Section of Cardiology, University of Illinois at Chicago, Chicago, IL 60612, USA.
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10
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Inhibition of human Nav1.5 sodium channels by strychnine and its analogs. Biochem Pharmacol 2011; 82:350-7. [DOI: 10.1016/j.bcp.2011.05.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2011] [Revised: 04/15/2011] [Accepted: 05/09/2011] [Indexed: 11/19/2022]
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Abstract
Atrial fibrillation (AF) is the most common clinically encountered abnormal heart beat. It is associated with an increased risk of stroke and symptoms of heart failure. Current therapies are directed toward controlling the rate of ventricular activation and preventing strokes through anticoagulation. Attempts at suppressing the arrhythmia are often ineffective, in part because the underlying pathogenesis is poorly understood. Recently, structural and electrical remodeling has been shown to occur during AF. These changes involve alterations in gene regulation and help perpetuate the arrhythmia. Some signals for remodeling are have been identified. Moreover, AF is associated with oxidative stress, and this redox imbalance may contribute to the altered gene regulation. One likely mediator of this change in transcriptional regulation is the redox sensitive transcription factor, nuclear factor-kappaB (NF-kappaB). Recently, NF-kappaB has been shown to downregulate transcription of the cardiac sodium channel in response to oxidative stress. NF-kappaB may contribute to the regulation of other ion channels, transcription factors, or splicing factors altered in AF and may represent a therapeutic target in AF management.
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Affiliation(s)
- Ge Gao
- Section of Cardiology, University of Illinois at Chicago, and the Jesse Brown VA Medical Center, Chicago, Illinois 60612, USA
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12
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Papaefthimiou C, Antonopoulou E, Theophilidis G. Inhibitory vs. protective effects of N-acetyl-l-cysteine (NAC) on the electromechanical properties of the spontaneously beating atria of the frog (Rana ridibunda): An ex vivo study. Toxicol In Vitro 2009; 23:272-80. [DOI: 10.1016/j.tiv.2008.12.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2008] [Revised: 11/04/2008] [Accepted: 12/05/2008] [Indexed: 10/21/2022]
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13
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Priest BT. On the Process of Finding Novel and Selective Sodium Channel Blockers for the Treatment of Diseases. TOPICS IN MEDICINAL CHEMISTRY 2008. [DOI: 10.1007/7355_2008_019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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14
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Clancy CE, Wehrens XHT. Mutation-specific effects of lidocaine in Brugada syndrome. Int J Cardiol 2007; 121:249-52. [PMID: 17761312 DOI: 10.1016/j.ijcard.2007.05.060] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2007] [Accepted: 05/19/2007] [Indexed: 12/31/2022]
Abstract
Brugada syndrome (BrS) is a hereditary cardiac disease characterized by right bundle-branch block, an elevation of the ST-segment in leads V1 through V3 on the electrocardiogram, and ventricular fibrillation that can lead to sudden cardiac death. Mutations in the cardiac sodium channel gene SCN5A, which encodes the alpha-subunit of the human cardiac voltage-dependent Na+ channel (Na(v)1.5), are identified in 15-30% of patients with BrS. Most SCN5A mutations lead to a 'loss-of-function' phenotype, reducing the Na+ current during the early phases of the action potential. Anti-arrhythmic drugs that affect Na+ channels typically block these Na+ channels, thereby exaggerating the ECG abnormalities and arrhythmogenicity in the BrS. However, the N406S mutation in SCN5A causes distinct gating defects and enhanced intermediate inactivation of Na+ channels, which led to unexpected pharmacological effects of lidocaine in a patient carrying this mutation. In the presence of the N406S mutation, use-dependent block by lidocaine is reduced and recovery from intermediate inactivation is hastened by lidocaine. These findings suggest that lidocaine may improve the Brugada phenotype in patients with N406S by increasing the availability of Na+ channels.
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15
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Kasi VS, Xiao HD, Shang LL, Iravanian S, Langberg J, Witham EA, Jiao Z, Gallego CJ, Bernstein KE, Dudley SC. Cardiac-restricted angiotensin-converting enzyme overexpression causes conduction defects and connexin dysregulation. Am J Physiol Heart Circ Physiol 2007; 293:H182-92. [PMID: 17337599 PMCID: PMC3160110 DOI: 10.1152/ajpheart.00684.2006] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Renin-angiotensin (RAS) system activation is associated with an increased risk of sudden death. Previously, we used cardiac-restricted angiotensin-converting enzyme (ACE) overexpression to construct a mouse model of RAS activation. These ACE 8/8 mice die prematurely and abruptly. Here, we have investigated cardiac electrophysiological abnormalities that may contribute to early mortality in this model. In ACE 8/8 mice, surface ECG voltages are reduced. Intracardiac electrograms showed atrial and ventricular potential amplitudes of 11% and 24% compared with matched wild-type (WT) controls. The atrioventricular (AV), atrio-Hisian (AH), and Hisian-ventricular (HV) intervals were prolonged 2.8-, 2.6-, and 3.9-fold, respectively, in ACE 8/8 vs. WT mice. Various degrees of AV nodal block were present only in ACE 8/8 mice. Intracardiac electrophysiology studies demonstrated that WT and heterozygote (HZ) mice were noninducible, whereas 83% of ACE 8/8 mice demonstrated ventricular tachycardia with burst pacing. Atrial connexin 40 (Cx40) and connexin 43 (Cx43) protein levels, ventricular Cx43 protein level, atrial and ventricular Cx40 mRNA abundances, ventricular Cx43 mRNA abundance, and atrial and ventricular cardiac Na(+) channel (Scn5a) mRNA abundances were reduced in ACE 8/8 compared with WT mice. ACE 8/8 mice demonstrated ventricular Cx43 dephosphorylation. Atrial and ventricular L-type Ca(2+) channel, Kv4.2 K(+) channel alpha-subunit, and Cx45 mRNA abundances and the peak ventricular Na(+) current did not differ between the groups. In isolated heart preparations, a connexin blocker, 1-heptanol (0.5 mM), produced an electrophysiological phenotype similar to that seen in ACE 8/8 mice. Therefore, cardiac-specific ACE overexpression resulted in changes in connexins consistent with the phenotype of low-voltage electrical activity, conduction defects, and induced ventricular arrhythmia. These results may help explain the increased risk of arrhythmia in states of RAS activation such as heart failure.
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Affiliation(s)
- Vijaykumar S Kasi
- Division of Cardiology, Atlanta VA Medical Center, 1670 Clairmont Road, Atlanta, GA 30033, USA
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16
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Stokoe KS, Balasubramaniam R, Goddard CA, Colledge WH, Grace AA, Huang CLH. Effects of flecainide and quinidine on arrhythmogenic properties of Scn5a+/- murine hearts modelling the Brugada syndrome. J Physiol 2007; 581:255-75. [PMID: 17303635 PMCID: PMC2075209 DOI: 10.1113/jphysiol.2007.128785] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Brugada syndrome (BrS) is associated with a loss of Na+ channel function and an increased incidence of rapid polymorphic ventricular tachycardia (VT) and sudden cardiac death. A programmed electrical stimulation (PES) technique assessed arrhythmic tendency in Langendorff-perfused wild-type (WT) and genetically modified (Scn5a+/-) 'loss-of-function' murine hearts in the presence and absence of flecainide and quinidine, and the extent to which Scn5a+/- hearts model the human BrS. Extra-stimuli (S2), applied to the right ventricular epicardium, followed trains of pacing stimuli (S1) at progressively reduced S1-S2 intervals. These triggered VT in 16 out of 29 untreated Scn5a+/- and zero out of 31 WT hearts. VT occurred in 11 out of 16 (10 microM) flecainide-treated WT and nine out of the 13 initially non-arrhythmogenic Scn5a+/- hearts treated with (1.0 microM) flecainide. Quinidine (10 microM) prevented VT in six out of six flecainide-treated WT and 13 out of the 16 arrhythmogenic Scn5a+/- hearts in parallel with its clinical effects. Paced electrogram fractionation analysis demonstrated increased electrogram durations, expressed as electrogram duration (EGD) ratios, with shortening S1-S2 intervals in arrhythmogenic Scn5a+/- hearts, and prolonged ventricular effective refractory periods (VERPs) in non-arrhythmogenic Scn5a+/- hearts. Flecainide increased EGD ratios in WT (at 10 microM) and non-arrhythmogenic Scn5a+/- hearts (at 1.0 microM), whereas quinidine (10 microM) reduced EGD ratios and prolonged VERPs in WT and arrhythmogenic Scn5a+/- hearts. However, epicardial and endocardial monophasic action potential recordings consistently demonstrated positive gradients of repolarization in WT, arrhythmogenic and non-arrhythmogenic Scn5a+/- hearts under all pharmacological conditions. Together, these findings demonstrate proarrhythmic effects of flecainide in WT and Scn5a+/- murine hearts that recapitulate its clinical effects. They further attribute the arrhythmogenic phenomena observed here to re-entrant substrates resulting from delayed epicardial activation despite an absence of transmural heterogeneities of repolarization, in sharp contrast to recent characterizations in 'gain-of-function' Scn5a+/Delta murine hearts modelling the long-QT(3) syndrome.
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Affiliation(s)
- Kate S Stokoe
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge CB2 3EG, UK
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Wallace CHR, Baczkó I, Jones L, Fercho M, Light PE. Inhibition of cardiac voltage-gated sodium channels by grape polyphenols. Br J Pharmacol 2006; 149:657-65. [PMID: 17016511 PMCID: PMC2014645 DOI: 10.1038/sj.bjp.0706897] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND AND PURPOSE The cardiovascular benefits of red wine consumption are often attributed to the antioxidant effects of its polyphenolic constituents, including quercetin, catechin and resveratrol. Inhibition of cardiac voltage-gated sodium channels (VGSCs) is antiarrhythmic and cardioprotective. As polyphenols may also modulate ion channels, and possess structural similarities to several antiarrhythmic VGSC inhibitors, we hypothesised that VGSC inhibition may contribute to cardioprotection by these polyphenols. EXPERIMENTAL APPROACH The whole-cell voltage-clamp technique was used to record peak and late VGSC currents (INa) from recombinant human heart NaV1.5 channels expressed in tsA201 cells. Right ventricular myocytes from rat heart were isolated and single myocytes were field-stimulated. Either calcium transients or contractility were measured using the calcium-sensitive dye Calcium-Green 1AM or video edge detection, respectively. KEY RESULTS The red grape polyphenols quercetin, catechin and resveratrol blocked peak INa with IC50s of 19.4 microM, 76.8 microM and 77.3 microM, respectively. In contrast to lidocaine, resveratrol did not exhibit any frequency-dependence of peak INa block. Late INa induced by the VGSC long QT mutant R1623Q was reduced by resveratrol and quercetin. Resveratrol and quercetin also blocked late INa induced by the toxin, ATX II, with IC50s of 26.1 microM and 24.9 microM, respectively. In field-stimulated myocytes, ATXII-induced increases in diastolic calcium were prevented and reversed by resveratrol. ATXII-induced contractile dysfunction was delayed and reduced by resveratrol. CONCLUSIONS AND IMPLICATIONS Our results indicate that several red grape polyphenols inhibit cardiac VGSCs and that this effect may contribute to the documented cardioprotective efficacy of red grape products.
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Affiliation(s)
- C H R Wallace
- Department of Pharmacology, University of Alberta, 9-58 Medical Sciences Building Edmonton, Alberta, Canada
| | - I Baczkó
- Department of Pharmacology, University of Alberta, 9-58 Medical Sciences Building Edmonton, Alberta, Canada
- Department of Pharmacology and Pharmacotherapy, Albert Szent-Györgyi Medical Center, University of Szeged Szeged, Hungary
| | - L Jones
- Department of Pharmacology, University of Alberta, 9-58 Medical Sciences Building Edmonton, Alberta, Canada
| | - M Fercho
- Department of Pharmacology, University of Alberta, 9-58 Medical Sciences Building Edmonton, Alberta, Canada
| | - P E Light
- Department of Pharmacology, University of Alberta, 9-58 Medical Sciences Building Edmonton, Alberta, Canada
- Author for correspondence:
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Niggli E, Kléber A, Weingart R. Founder of cardiac cellular electrophysiology: honouring Silvio Weidmann, 7 April 1921- 11 July 2005. J Physiol 2006; 570:431-2. [PMID: 16322050 PMCID: PMC1479882 DOI: 10.1113/jphysiol.2005.101550] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Ernst Niggli
- Department of Physiology, University of Bern, Switzerland.
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Mori K, Ito H, Toda Y, Hashimoto T, Miyazaki M, Saijo T, Kuroda Y. Successful Management of Intractable Epilepsy with Lidocaine Tapes and Continuous Subcutaneous Lidocaine Infusion. Epilepsia 2004; 45:1287-90. [PMID: 15461684 DOI: 10.1111/j.0013-9580.2004.17304.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
PURPOSE We report the successful management of a 10-year-old girl with intractable frontal lobe epilepsy by using lidocaine tapes and continuous subcutaneous lidocaine infusion. METHODS This patient's seizures were refractory to conventional antiepileptic drugs (AEDs) and mexiletine, but they responded well to the intravenous infusion of lidocaine. The intravenous infusion of lidocaine was replaced by lidocaine tape therapy, and subsequently by continuous subcutaneous lidocaine infusion therapy. The lidocaine tape (Penles, Nihon Lederle, Tokyo Japan) used was a stamp-sized (30.5 x 50.0 mm) tape containing 18 mg of lidocaine. We used 25 lidocaine tapes every 12 h (50 tapes/day). Lidocaine hydrochloride (10%) was administered continuously at a dose of 1.5 mg/kg/h (0.3 ml/hour) through a 27-G needle that was inserted in the subcutaneous tissue. RESULTS Lidocaine tape therapy showed good efficacy for 1 year. After that, six lidocaine tapes were added 6 h after the exchange of 25 lidocaine tapes [62 tapes/day (25,6,25,6)], because the seizures became frequent when the lidocaine tapes were being exchanged. The seizures were then well controlled, but dermatitis due to the lidocaine tapes grew serious, and lidocaine tape therapy had to be stopped. Continuous subcutaneous infusion of lidocaine applied in place of lidocaine tapes provided long-term seizure control without remarkable side effects. CONCLUSIONS Lidocaine tape therapy and continuous subcutaneous lidocaine infusion therapy were considered to be useful for controlling this patient's seizures. This is the first report to describe the efficacy of continuous subcutaneous lidocaine infusion therapy for epilepsy.
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Affiliation(s)
- Kenji Mori
- Department of Pediatrics, School of Medicine, Tokushima University, Kuramoto-cho, Japan.
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Abstract
Genetic variability has recently been implicated in the development of familial epilepsy syndromes and in heterogeneous responses of epilepsy patients to drug treatment. Mutations in distinct proteins have been shown to underlie the development of epilepsy, increase propensity for drug resistance, and alter drug metabolism. Improved understanding of how individual genetic variability may alter the efficacy of pharmacological therapeutic interventions is an important and timely goal. The investigation of relationships between genotype and patient responses to drug treatment is termed pharmacogenomics.
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Affiliation(s)
- Colleen E Clancy
- Department of Pharmacology, Columbia University, College of Physicians and Surgeons, 630 W. 168th Street, New York, NY 10032, USA.
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