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Bragard J, Witt A, Laroze D, Hawks C, Elorza J, Rodríguez Cantalapiedra I, Peñaranda A, Echebarria B. Conductance heterogeneities induced by multistability in the dynamics of coupled cardiac gap junctions. CHAOS (WOODBURY, N.Y.) 2021; 31:073144. [PMID: 34340360 DOI: 10.1063/5.0053651] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 07/08/2021] [Indexed: 06/13/2023]
Abstract
In this paper, we study the propagation of the cardiac action potential in a one-dimensional fiber, where cells are electrically coupled through gap junctions (GJs). We consider gap junctional gate dynamics that depend on the intercellular potential. We find that different GJs in the tissue can end up in two different states: a low conducting state and a high conducting state. We first present evidence of the dynamical multistability that occurs by setting specific parameters of the GJ dynamics. Subsequently, we explain how the multistability is a direct consequence of the GJ stability problem by reducing the dynamical system's dimensions. The conductance dispersion usually occurs on a large time scale, i.e., thousands of heartbeats. The full cardiac model simulations are computationally demanding, and we derive a simplified model that allows for a reduction in the computational cost of four orders of magnitude. This simplified model reproduces nearly quantitatively the results provided by the original full model. We explain the discrepancies between the two models due to the simplified model's lack of spatial correlations. This simplified model provides a valuable tool to explore cardiac dynamics over very long time scales. That is highly relevant in studying diseases that develop on a large time scale compared to the basic heartbeat. As in the brain, plasticity and tissue remodeling are crucial parameters in determining the action potential wave propagation's stability.
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Affiliation(s)
- J Bragard
- Departamento de Física y Matemática Aplicada, Universidad de Navarra, Pamplona 31080, Spain
| | - A Witt
- Max-Planck Institute, Gottingen 37077, Germany
| | - D Laroze
- Instituto de Alta Investigación, CEDENNA, Universidad de Tarapacá, Casilla 7D, Arica, Chile
| | - C Hawks
- Departamento de Física y Matemática Aplicada, Universidad de Navarra, Pamplona 31080, Spain
| | - J Elorza
- Departamento de Física y Matemática Aplicada, Universidad de Navarra, Pamplona 31080, Spain
| | | | - A Peñaranda
- Departament de Física, Universitat Politècnica de Catalunya, Barcelona 08068, Spain
| | - B Echebarria
- Departament de Física, Universitat Politècnica de Catalunya, Barcelona 08068, Spain
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2
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Arteyeva NV. Dispersion of ventricular repolarization: Temporal and spatial. World J Cardiol 2020; 12:437-449. [PMID: 33014291 PMCID: PMC7509993 DOI: 10.4330/wjc.v12.i9.437] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 06/11/2020] [Accepted: 08/25/2020] [Indexed: 02/06/2023] Open
Abstract
Repolarization heterogeneity (RH) is an intrinsic property of ventricular myocardium and the reason for T-wave formation on electrocardiogram (ECG). Exceeding the physiologically based RH level is associated with appearance of life-threatening ventricular arrhythmias and sudden cardiac death. In this regard, an accurate and comprehensive evaluation of the degree of RH parameters is of importance for assessment of heart state and arrhythmic risk. This review is devoted to comprehensive consideration of RH phenomena in terms of electrophysiological processes underlying RH, cardiac electric field formation during ventricular repolarization, as well as clinical significance of RH and its reflection on ECG parameters. The formation of transmural, apicobasal, left-to-right and anterior-posterior gradients of action potential durations and end of repolarization times resulting from the heterogenous distribution of repolarizing ion currents and action potential morphology throughout the heart ventricles, and the different sensitivity of myocardial cells in different ventricular regions to the action of pharmacological agents, temperature, frequency of stimulation, etc., are being discussed. The review is focused on the fact that RH has different aspects – temporal and spatial, global and local; ECG reflection of various RH aspects and their clinical significance are being discussed. Strategies for comprehensive assessment of ventricular RH using different ECG indices reflecting various RH aspects are presented.
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Affiliation(s)
- Natalia V Arteyeva
- Laboratory of Cardiac Physiology, Institute of Physiology of Komi Science Centre of the Ural Branch of the Russian Academy of Sciences, Syktyvkar 167982, Russia
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3
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Blok M, Boukens BJ. Mechanisms of Arrhythmias in the Brugada Syndrome. Int J Mol Sci 2020; 21:ijms21197051. [PMID: 32992720 PMCID: PMC7582368 DOI: 10.3390/ijms21197051] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 09/15/2020] [Accepted: 09/21/2020] [Indexed: 12/13/2022] Open
Abstract
Arrhythmias in Brugada syndrome patients originate in the right ventricular outflow tract (RVOT). Over the past few decades, the characterization of the unique anatomy and electrophysiology of the RVOT has revealed the arrhythmogenic nature of this region. However, the mechanisms that drive arrhythmias in Brugada syndrome patients remain debated as well as the exact site of their occurrence in the RVOT. Identifying the site of origin and mechanism of Brugada syndrome would greatly benefit the development of mechanism-driven treatment strategies.
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Affiliation(s)
- Michiel Blok
- Department of Medical Biology, Amsterdam University Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands
- Department of Experimental Cardiology, Amsterdam University Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands
| | - Bastiaan J. Boukens
- Department of Medical Biology, Amsterdam University Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands
- Department of Experimental Cardiology, Amsterdam University Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands
- Correspondence: ; Tel.: +31-(0)20-566-4659
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4
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Pianca N, Di Bona A, Lazzeri E, Costantini I, Franzoso M, Prando V, Armani A, Rizzo S, Fedrigo M, Angelini A, Basso C, Pavone FS, Rubart M, Sacconi L, Zaglia T, Mongillo M. Cardiac sympathetic innervation network shapes the myocardium by locally controlling cardiomyocyte size through the cellular proteolytic machinery. J Physiol 2019; 597:3639-3656. [DOI: 10.1113/jp276200] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 05/21/2019] [Indexed: 01/07/2023] Open
Affiliation(s)
- Nicola Pianca
- Veneto Institute of Molecular Medicine Padova Italy
- Department of Biomedical SciencesUniversity of Padova Padova Italy
| | - Anna Di Bona
- Veneto Institute of Molecular Medicine Padova Italy
- Department of Cardiac, Thoracic, Vascular Sciences and Public HealthUniversity of Padova Padova Italy
| | - Erica Lazzeri
- European Laboratory for Non‐linear SpectroscopyUniversity of Florence Florence Italy
| | - Irene Costantini
- European Laboratory for Non‐linear SpectroscopyUniversity of Florence Florence Italy
- National Institute of Optics, National Research CouncilUniversity of Florence Florence Italy
| | - Mauro Franzoso
- Veneto Institute of Molecular Medicine Padova Italy
- Department of Biomedical SciencesUniversity of Padova Padova Italy
| | - Valentina Prando
- Veneto Institute of Molecular Medicine Padova Italy
- Department of Cardiac, Thoracic, Vascular Sciences and Public HealthUniversity of Padova Padova Italy
| | - Andrea Armani
- Veneto Institute of Molecular Medicine Padova Italy
- Department of Biomedical SciencesUniversity of Padova Padova Italy
| | - Stefania Rizzo
- Department of Cardiac, Thoracic, Vascular Sciences and Public HealthUniversity of Padova Padova Italy
| | - Marny Fedrigo
- Department of Cardiac, Thoracic, Vascular Sciences and Public HealthUniversity of Padova Padova Italy
| | - Annalisa Angelini
- Department of Cardiac, Thoracic, Vascular Sciences and Public HealthUniversity of Padova Padova Italy
| | - Cristina Basso
- Department of Cardiac, Thoracic, Vascular Sciences and Public HealthUniversity of Padova Padova Italy
| | - Francesco S. Pavone
- European Laboratory for Non‐linear SpectroscopyUniversity of Florence Florence Italy
- National Institute of Optics, National Research CouncilUniversity of Florence Florence Italy
- Department of Physics and AstronomyUniversity of Florence Florence Italy
| | - Michael Rubart
- Indiana University School of Medicine Indianapolis IN USA
| | - Leonardo Sacconi
- European Laboratory for Non‐linear SpectroscopyUniversity of Florence Florence Italy
- National Institute of Optics, National Research CouncilUniversity of Florence Florence Italy
| | - Tania Zaglia
- Veneto Institute of Molecular Medicine Padova Italy
- Department of Biomedical SciencesUniversity of Padova Padova Italy
- Department of Cardiac, Thoracic, Vascular Sciences and Public HealthUniversity of Padova Padova Italy
| | - Marco Mongillo
- Veneto Institute of Molecular Medicine Padova Italy
- Department of Biomedical SciencesUniversity of Padova Padova Italy
- CNR Institute of Neuroscience Padova Italy
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5
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Dusturia N, Choi SW, Song KS, Lim KM. Effect of myocardial heterogeneity on ventricular electro-mechanical responses: a computational study. Biomed Eng Online 2019; 18:23. [PMID: 30871548 PMCID: PMC6419335 DOI: 10.1186/s12938-019-0640-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Accepted: 03/06/2019] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND The heart wall exhibits three layers of different thicknesses: the outer epicardium, mid-myocardium, and inner endocardium. Among these layers, the mid-myocardium is typically the thickest. As indicated by preliminary studies, heart-wall layers exhibit various characteristics with regard to electrophysiology, pharmacology, and pathology. Construction of an accurate three-dimensional (3D) model of the heart is important for predicting physiological behaviors. However, the wide variability of myocardial shapes and the unclear edges between the epicardium and soft tissues are major challenges in the 3D model segmentation approach for identifying the boundaries of the epicardium, mid-myocardium, and endocardium. Therefore, this results in possible variations in the heterogeneity ratios between the epicardium, mid-myocardium, and endocardium. The objective of this study was to observe the effects of different thickness ratios of the epicardium, mid-myocardium, and endocardium on cardiac arrhythmogenesis, reentry instability, and mechanical responses during arrhythmia. METHODS We used a computational method and simulated three heterogeneous ventricular models: Model 1 had the thickest M cell layer and thinnest epicardium and endocardium. Model 2 had intermediate layer thicknesses. Model 3 exhibited the thinnest mid-myocardium and thickest epicardium and endocardium. Electrical and mechanical simulations of the three heterogeneous models were performed under normal sinus rhythm and reentry conditions. RESULTS Model 1 exhibited the highest probability of terminating reentrant waves, and Model 3 exhibited to experience greater cardiac arrhythmia. In the reentry simulation, at 8 s, Model 3 generated the largest number of rotors (eight), while Models 1 and 2 produced five and seven rotors, respectively. There was no significant difference in the cardiac output obtained during the sinus rhythm. Under the reentry condition, the highest cardiac output was generated by Model 1 (19 mL/s), followed by Model 2 (9 mL/s) and Model 3 (7 mL/s). CONCLUSIONS A thicker mid-myocardium led to improvements in the pumping efficacy and contractility and reduced the probability of cardiac arrhythmia. Conversely, thinner M cell layers generated more unstable reentrant spiral waves and hindered the ventricular pumping.
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Affiliation(s)
- Nida Dusturia
- Department of IT Convergence Engineering, Kumoh National Institute of Technology, 61 Daehak-ro, Gumi, Gyeongbuk, 39253, Republic of Korea
| | - Seong Wook Choi
- Department of Mechanical and Biomedical Engineering, Kangwon National University, Chuncheon, Republic of Korea
| | - Kwang Soup Song
- Department of Medical IT Convergence Engineering, Kumoh National Institute of Technology, Gumi, Republic of Korea
| | - Ki Moo Lim
- Department of IT Convergence Engineering, Kumoh National Institute of Technology, 61 Daehak-ro, Gumi, Gyeongbuk, 39253, Republic of Korea.
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6
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Colman MA, Perez Alday EA, Holden AV, Benson AP. Trigger vs. Substrate: Multi-Dimensional Modulation of QT-Prolongation Associated Arrhythmic Dynamics by a hERG Channel Activator. Front Physiol 2017; 8:757. [PMID: 29046643 PMCID: PMC5632683 DOI: 10.3389/fphys.2017.00757] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 09/19/2017] [Indexed: 11/13/2022] Open
Abstract
Background: Prolongation of the QT interval of the electrocardiogram (ECG), underlain by prolongation of the action potential duration (APD) at the cellular level, is linked to increased vulnerability to cardiac arrhythmia. Pharmacological management of arrhythmia associated with QT prolongation is typically achieved through attempting to restore APD to control ranges, reversing the enhanced vulnerability to Ca2+-dependent afterdepolarisations (arrhythmia triggers) and increased transmural dispersion of repolarisation (arrhythmia substrate) associated with APD prolongation. However, such pharmacological modulation has been demonstrated to have limited effectiveness. Understanding the integrative functional impact of pharmacological modulation requires simultaneous investigation of both the trigger and substrate. Methods: We implemented a multi-scale (cell and tissue) in silico approach using a model of the human ventricular action potential, integrated with a model of stochastic 3D spatiotemporal Ca2+ dynamics, and parameter modification to mimic prolonged QT conditions. We used these models to examine the efficacy of the hERG activator MC-II-157c in restoring APD to control ranges, examined its effects on arrhythmia triggers and substrates, and the interaction of these arrhythmia triggers and substrates. Results: QT prolongation conditions promoted the development of spontaneous release events underlying afterdepolarisations during rapid pacing. MC-II-157c applied to prolonged QT conditions shortened the APD, inhibited the development of afterdepolarisations and reduced the probability of afterdepolarisations manifesting as triggered activity in single cells. In tissue, QT prolongation resulted in an increased transmural dispersion of repolarisation, which manifested as an increased vulnerable window for uni-directional conduction block. In some cases, MC-II-157c further increased the vulnerable window through its effects on INa. The combination of stochastic release event modulation and transmural dispersion of repolarisation modulation by MC-II-157c resulted in an integrative behavior wherein the arrhythmia trigger is reduced but the arrhythmia substrate is increased, leading to variable and non-linear overall vulnerability to arrhythmia. Conclusion: The relative balance of reduced trigger and increased substrate underlies a multi-dimensional role of MC-II-157c in modulation of cardiac arrhythmia vulnerability associated with prolonged QT interval.
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Affiliation(s)
- Michael A Colman
- School of Biomedical Sciences and Multidisciplinary Cardiovascular Research Centre, University of Leeds, Leeds, United Kingdom
| | - Erick A Perez Alday
- Division of Cardiovascular Medicine, Oregon Health and Science University, Portland, OR, United States
| | - Arun V Holden
- School of Biomedical Sciences and Multidisciplinary Cardiovascular Research Centre, University of Leeds, Leeds, United Kingdom
| | - Alan P Benson
- School of Biomedical Sciences and Multidisciplinary Cardiovascular Research Centre, University of Leeds, Leeds, United Kingdom
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7
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Kofron CM, Kim TY, King ME, Xie A, Feng F, Park E, Qu Z, Choi BR, Mende U. G q-activated fibroblasts induce cardiomyocyte action potential prolongation and automaticity in a three-dimensional microtissue environment. Am J Physiol Heart Circ Physiol 2017; 313:H810-H827. [PMID: 28710068 DOI: 10.1152/ajpheart.00181.2017] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 06/13/2017] [Accepted: 07/03/2017] [Indexed: 11/22/2022]
Abstract
Cardiac fibroblasts (CFs) are known to regulate cardiomyocyte (CM) function in vivo and in two-dimensional in vitro cultures. This study examined the effect of CF activation on the regulation of CM electrical activity in a three-dimensional (3-D) microtissue environment. Using a scaffold-free 3-D platform with interspersed neonatal rat ventricular CMs and CFs, Gq-mediated signaling was selectively enhanced in CFs by Gαq adenoviral infection before coseeding with CMs in nonadhesive hydrogels. After 3 days, the microtissues were analyzed by signaling assay, histological staining, quantitative PCR, Western blots, optical mapping with voltage- or Ca2+-sensitive dyes, and microelectrode recordings of CF resting membrane potential (RMPCF). Enhanced Gq signaling in CFs increased microtissue size and profibrotic and prohypertrophic markers. Expression of constitutively active Gαq in CFs prolonged CM action potential duration (by 33%) and rise time (by 31%), prolonged Ca2+ transient duration (by 98%) and rise time (by 65%), and caused abnormal electrical activity based on depolarization-induced automaticity. Constitutive Gq activation in CFs also depolarized RMPCF from -33 to -20 mV and increased connexin 43 and connexin 45 expression. Computational modeling confers that elevated RMPCF and increased cell-cell coupling between CMs and CFs in a 3-D environment could lead to automaticity. In conclusion, our data demonstrate that CF activation alone is capable of altering action potential and Ca2+ transient characteristics of CMs, leading to proarrhythmic electrical activity. Our results also emphasize the importance of a 3-D environment where cell-cell interactions are prevalent, underscoring that CF activation in 3-D tissue plays a significant role in modulating CM electrophysiology and arrhythmias.NEW & NOTEWORTHY In a three-dimensional microtissue model, which lowers baseline activation of cardiac fibroblasts but enables cell-cell, paracrine, and cell-extracellular matrix interactions, we demonstrate that selective cardiac fibroblast activation by enhanced Gq signaling, a pathophysiological trigger in the diseased heart, modulates cardiomyocyte electrical activity, leading to proarrhythmogenic automaticity.
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Affiliation(s)
- C M Kofron
- Cardiovascular Research Center, Cardiovascular Institute, Rhode Island Hospital and Alpert Medical School of Brown University, Providence, Rhode Island; and
| | - T Y Kim
- Cardiovascular Research Center, Cardiovascular Institute, Rhode Island Hospital and Alpert Medical School of Brown University, Providence, Rhode Island; and
| | - M E King
- Cardiovascular Research Center, Cardiovascular Institute, Rhode Island Hospital and Alpert Medical School of Brown University, Providence, Rhode Island; and
| | - A Xie
- Cardiovascular Research Center, Cardiovascular Institute, Rhode Island Hospital and Alpert Medical School of Brown University, Providence, Rhode Island; and
| | - F Feng
- Cardiovascular Research Center, Cardiovascular Institute, Rhode Island Hospital and Alpert Medical School of Brown University, Providence, Rhode Island; and
| | - E Park
- Cardiovascular Research Center, Cardiovascular Institute, Rhode Island Hospital and Alpert Medical School of Brown University, Providence, Rhode Island; and
| | - Z Qu
- Department of Medicine, University of California, Los Angeles, California
| | - B-R Choi
- Cardiovascular Research Center, Cardiovascular Institute, Rhode Island Hospital and Alpert Medical School of Brown University, Providence, Rhode Island; and
| | - U Mende
- Cardiovascular Research Center, Cardiovascular Institute, Rhode Island Hospital and Alpert Medical School of Brown University, Providence, Rhode Island; and
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8
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Lee MY. T wave. INTERNATIONAL JOURNAL OF ARRHYTHMIA 2017. [DOI: 10.18501/arrhythmia.2017.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
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9
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Transmural electrophysiological heterogeneity, the T-wave and ventricular arrhythmias. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2016; 122:202-214. [DOI: 10.1016/j.pbiomolbio.2016.05.009] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 04/21/2016] [Accepted: 05/03/2016] [Indexed: 01/05/2023]
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10
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Fridman MD, Liu J, Sun Y, Hamilton RM. Microinjection Technique for Assessment of Gap Junction Function. Methods Mol Biol 2016; 1437:145-154. [PMID: 27207292 DOI: 10.1007/978-1-4939-3664-9_10] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Gap junctions are essential for the proper function of many native mammalian tissues including neurons, cardiomyocytes, embryonic tissues, and muscle. Assessing these channels is therefore fundamental to understanding disease pathophysiology, developing therapies for a multitude of acquired and genetic conditions, and providing novel approaches to drug delivery and cellular communication. Microinjection is a robust, albeit difficult, technique, which provides considerable information that is superior to many of the simpler techniques due to its ability to isolate cells, quantify kinetics, and allow cross-comparison of multiple cell lines. Despite its user-dependent nature, the strengths of the technique are considerable and with the advent of new, automation technologies may improve further. This text describes the basic technique of microinjection and briefly discusses modern automation advances that can improve the success rates of this technique.
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Affiliation(s)
- Michael D Fridman
- Department of Physiology and Experimental Medicine, Hospital for Sick Children, Toronto, ON, Canada
| | - Jun Liu
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, ON, Canada
| | - Yu Sun
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, ON, Canada
| | - Robert M Hamilton
- Department of Physiology and Experimental Medicine, Hospital for Sick Children, Toronto, ON, Canada.
- Department of Pediatrics - Division of Cardiology, Hospital for Sick Children, Toronto, ON, Canada.
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11
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Miura M, Nagano T, Murai N, Taguchi Y, Handoh T, Satoh M, Miyata S, Miller L, Shindoh C, Stuyvers BD. Effect of Carbenoxolone on Arrhythmogenesis in Rat Ventricular Muscle. Circ J 2016; 80:76-84. [DOI: 10.1253/circj.cj-15-0401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Masahito Miura
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine
| | - Tsuyoshi Nagano
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine
| | - Naomi Murai
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine
| | - Yuhto Taguchi
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine
| | - Tetsuya Handoh
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine
| | - Minami Satoh
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine
| | - Satoshi Miyata
- Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine
| | - Lawson Miller
- Faculty of Medicine, Biomedical Sciences, Memorial University
| | - Chiyohiko Shindoh
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine
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12
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Kessler EL, Boulaksil M, van Rijen HVM, Vos MA, van Veen TAB. Passive ventricular remodeling in cardiac disease: focus on heterogeneity. Front Physiol 2014; 5:482. [PMID: 25566084 PMCID: PMC4273631 DOI: 10.3389/fphys.2014.00482] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Accepted: 11/24/2014] [Indexed: 12/20/2022] Open
Abstract
Passive ventricular remodeling is defined by the process of molecular ventricular adaptation to different forms of cardiac pathophysiology. It includes changes in tissue architecture, such as hypertrophy, fiber disarray, alterations in cell size and fibrosis. Besides that, it also includes molecular remodeling of gap junctions, especially those composed by Connexin43 proteins (Cx43) in the ventricles that affect cell-to-cell propagation of the electrical impulse, and changes in the sodium channels that modify excitability. All those alterations appear mainly in a heterogeneous manner, creating irregular and inhomogeneous electrical and mechanical coupling throughout the heart. This can predispose to reentry arrhythmias and adds to a further deterioration into heart failure. In this review, passive ventricular remodeling is described in Hypertrophic Cardiomyopathy (HCM), Dilated Cardiomyopathy (DCM), Ischemic Cardiomyopathy (ICM), and Arrhythmogenic Cardiomyopathy (ACM), with a main focus on the heterogeneity of those alterations mentioned above.
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Affiliation(s)
- Elise L Kessler
- Division of Heart and Lungs, Department of Medical Physiology, University Medical Center Utrecht Utrecht, Netherlands
| | - Mohamed Boulaksil
- Division of Heart and Lungs, Department of Medical Physiology, University Medical Center Utrecht Utrecht, Netherlands ; Department of Cardiology, Radboud University Medical Center Nijmegen, Netherlands
| | - Harold V M van Rijen
- Division of Heart and Lungs, Department of Medical Physiology, University Medical Center Utrecht Utrecht, Netherlands
| | - Marc A Vos
- Division of Heart and Lungs, Department of Medical Physiology, University Medical Center Utrecht Utrecht, Netherlands
| | - Toon A B van Veen
- Division of Heart and Lungs, Department of Medical Physiology, University Medical Center Utrecht Utrecht, Netherlands
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13
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Ge G, Zhang Q, Ma J, Qiao Z, Huang J, Cheng W, Wang H. Protective effect of Salvia miltiorrhiza aqueous extract on myocardium oxidative injury in ischemic-reperfusion rats. Gene 2014; 546:97-103. [PMID: 24831834 DOI: 10.1016/j.gene.2014.05.021] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Revised: 04/23/2014] [Accepted: 05/10/2014] [Indexed: 01/13/2023]
Abstract
Salvia miltiorrhiza has strong antioxidative activity. They may have a strong potential as cardioprotective agents in ischemic-reperfusion injury. Experiments were carried out in Sprague-Dawley rats with myocardium ischemia reperfusion (IR). Myocardial injuries during IR were determined by changes in electrocardiogram analysis of arrhythmias, antioxidant enzyme activities, AST, CK-MB, lactate dehydrogenase (LDH) levels, and myocyte apoptosis. Results showed that S. miltiorrhiza aqueous extract (SAME) pre-treatment significantly decreased the ST-segment (ΣST120) and myocardium MDA, AST, CK-MB, lactate dehydrogenase (LDH) levels, increased myocardium antioxidant enzyme activities, and inhibit myocardium cell apoptosis. Furthermore, the SAME pre-treatment significantly upregulated p-JAK2 and p-STAT3 protein expression, decreased myocardium TNF-α and IL-6 concentrations in IR rats. The levels of TNF-α and IL-6 were positively correlated with the changes in myocardium p-JAK2 and p-STAT3 protein expression levels in IR rats. It can be concluded that the SAME pre-treatment has anti-ischemic and anti-apoptosis activity in heart IR rats. SAME pre-treatment protects heart against IR injury, at least in part, through its stimulating effects on injury-induced deactivation of JAK2/STAT3 signaling pathway.
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Affiliation(s)
- Guanghao Ge
- Department of Cardiology, Fengxian Branch of Shanghai 6th People's Hospital, Shanghai 201400, China
| | - Qiong Zhang
- Department of Cardiology, Fengxian Branch of Shanghai 6th People's Hospital, Shanghai 201400, China
| | - Jiangwei Ma
- Department of Cardiology, Fengxian Branch of Shanghai 6th People's Hospital, Shanghai 201400, China.
| | - Zengyong Qiao
- Department of Cardiology, Fengxian Branch of Shanghai 6th People's Hospital, Shanghai 201400, China.
| | - Jianhua Huang
- Department of Cardiology, Fengxian Branch of Shanghai 6th People's Hospital, Shanghai 201400, China
| | - Wenbo Cheng
- Department of Cardiology, Fengxian Branch of Shanghai 6th People's Hospital, Shanghai 201400, China
| | - Hongwei Wang
- Department of Cardiology, Fengxian Branch of Shanghai 6th People's Hospital, Shanghai 201400, China
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14
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Liu J, Siragam V, Chen J, Fridman MD, Hamilton RM, Sun Y. High-throughput measurement of gap junctional intercellular communication. Am J Physiol Heart Circ Physiol 2014; 306:H1708-13. [PMID: 24778169 DOI: 10.1152/ajpheart.00110.2014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Gap junctional intercellular communication (GJIC) is a critical part of cellular activities and is necessary for electrical propagation among contacting cells. Disorders of gap junctions are a major cause for cardiac arrhythmias. Dye transfer through microinjection is a conventional technique for measuring GJIC. To overcome the limitations of manual microinjection and perform high-throughput GJIC measurement, here we present a new robotic microinjection system that is capable of injecting a large number of cells at a high speed. The highly automated system enables large-scale cell injection (thousands of cells vs. a few cells) without major operator training. GJIC of three cell lines of differing gap junction density, i.e., HeLa, HEK293, and HL-1, was evaluated. The effect of a GJIC inhibitor (18-α-glycyrrhetinic acid) was also quantified in the three cell lines. System operation speed, success rate, and cell viability rate were quantitatively evaluated based on robotic microinjection of over 4,000 cells. Injection speed was 22.7 cells per min, with 95% success for cell injection and >90% survival. Dye transfer cell counts and dye transfer distance correlated with the expected connexin expression of each cell type, and inhibition of dye transfer correlated with the concentration of GJIC inhibitor. Additionally, real-time monitoring of dye transfer enables the calculation of coefficients of molecular diffusion through gap junctions. This robotic microinjection dye transfer technique permits rapid assessment of gap junction function in confluent cell cultures.
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Affiliation(s)
- Jun Liu
- Advanced Micro and Nanosystems Laboratory, University of Toronto, Toronto, Ontario, Canada; and
| | - Vinayakumar Siragam
- Division of Cardiology, the Hospital of Sick Children, Toronto, Ontario, Canada
| | - Jun Chen
- Advanced Micro and Nanosystems Laboratory, University of Toronto, Toronto, Ontario, Canada; and
| | - Michael D Fridman
- Division of Cardiology, the Hospital of Sick Children, Toronto, Ontario, Canada
| | - Robert M Hamilton
- Division of Cardiology, the Hospital of Sick Children, Toronto, Ontario, Canada
| | - Yu Sun
- Advanced Micro and Nanosystems Laboratory, University of Toronto, Toronto, Ontario, Canada; and
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15
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de Oliveira BL, Rocha BM, Barra LPS, Toledo EM, Sundnes J, Weber dos Santos R. Effects of deformation on transmural dispersion of repolarization using in silico models of human left ventricular wedge. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2013; 29:1323-1337. [PMID: 23794390 DOI: 10.1002/cnm.2570] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Accepted: 11/08/2012] [Indexed: 06/02/2023]
Abstract
Mechanical deformation affects the electrical activity of the heart through multiple feedback loops. The purpose of this work is to study the effect of deformation on transmural dispersion of repolarization and on surface electrograms using an in silico human ventricular wedge. To achieve this purpose, we developed a strongly coupled electromechanical cell model by coupling a human left ventricle electrophysiology model and an active contraction model reparameterized for human cells. This model was then embedded in tissue simulations on the basis of bidomain equations and nonlinear solid mechanics. The coupled model was used to evaluate effects of mechanical deformation on important features of repolarization and electrograms. Our results indicate an increase in the T-wave amplitude of the surface electrograms in simulations that account for the effects of cardiac deformation. This increased T-wave amplitude can be explained by changes to the coupling between neighboring myocytes, also known as electrotonic effect. The thickening of the ventricular wall during repolarization contributes to the decoupling of cells in the transmural direction, enhancing action potential heterogeneity and increasing both transmural repolarization dispersion and T-wave amplitude of surface electrograms. The simulations suggest that a considerable percentage of the T-wave amplitude (15%) may be related to cardiac deformation.
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Affiliation(s)
- B L de Oliveira
- Simula Research Laboratory, Lysaker, Norway; Graduate Program in Computational Modeling of the Federal University of Juiz de Fora, Brazil
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16
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Janse MJ, Coronel R, Opthof T, Sosunov EA, Anyukhovsky EP, Rosen MR. Repolarization gradients in the intact heart: transmural or apico-basal? PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2012; 109:6-15. [PMID: 22446189 DOI: 10.1016/j.pbiomolbio.2012.03.001] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Revised: 02/17/2012] [Accepted: 03/06/2012] [Indexed: 01/31/2023]
Abstract
Controversies regarding the genesis of the T wave in the electrocardiogram and the role of midmural M cells in the intact heart include: In normal, intact canine and human hearts there is no significant transmural gradient in repolarization times. The T wave results primarily from apico-basal differences in repolarization times. Also, in the intact heart there is no midmural region of prolonged action potential duration. This contrasts with isolated preparations, such as the wedge preparation or myocardial slices or disaggregated myocytes in which M cells, with action potentials longer than those of endocardial and epicardial myocardium, can be found. This disparity in action potential duration probably results from partial uncoupling of myocardial cells in the regions where measurements are made, e.g., the cut surface of a wedge preparation. In regions of a wedge where cellular coupling is normal, or in isolated myocardial bundles or sheets, no evidence for M cells is detected. In some wedge preparations, a drug-induced large transmural repolarization gradient, involving M cells, can lead to Torsade de Pointes, possibly caused by so-called phase two reentry. In contrast, when a gradient of repolarization times of more than 100 ms was created in intact hearts, no evidence for reentry was found and no spontaneous arrhythmias occurred. In conclusion, in the intact heart, M cells appear not to contribute to repolarization gradients and arrhythmias. Furthermore, no significant repolarization gradients between endocardium and epicardium exist. The T wave in the body surface electrocardiogram is caused by apico-basal and anterior-posterior differences in repolarization times.
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Affiliation(s)
- Michiel J Janse
- The Experimental Cardiology Group, Heart Centre, Academic Medical Centre, Amsterdam, The Netherlands
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17
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Vesentini N, Barsanti C, Martino A, Kusmic C, Ripoli A, Rossi A, L'Abbate A. Selection of reference genes in different myocardial regions of an in vivo ischemia/reperfusion rat model for normalization of antioxidant gene expression. BMC Res Notes 2012; 5:124. [PMID: 22377061 PMCID: PMC3392735 DOI: 10.1186/1756-0500-5-124] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2011] [Accepted: 02/29/2012] [Indexed: 11/24/2022] Open
Abstract
Background Changes in cardiac gene expression due to myocardial injury are usually assessed in whole heart tissue. However, as the heart is a heterogeneous system, spatial and temporal heterogeneity is expected in gene expression. Results In an ischemia/reperfusion (I/R) rat model we evaluated gene expression of mitochondrial and cytoplasmatic superoxide dismutase (MnSod, Cu-ZnSod) and thioredoxin reductase (trxr1) upon short (4 h) and long (72 h) reperfusion times in the right ventricle (RV), and in the ischemic/reperfused (IRR) and the remote region (RR) of the left ventricle. Gene expression was assessed by Real-time reverse-transcription quantitative PCR (RT-qPCR). In order to select most stable reference genes suitable for normalization purposes, in each myocardial region we tested nine putative reference genes by geNorm analysis. The genes investigated were: Actin beta (actb), Glyceraldehyde-3-P-dehydrogenase (gapdh), Ribosomal protein L13A (rpl13a), Tyrosine 3-monooxygenase (ywhaz), Beta-glucuronidase (gusb), Hypoxanthine guanine Phosphoribosyltransferase 1 (hprt), TATA binding box protein (tbp), Hydroxymethylbilane synthase (hmbs), Polyadenylate-binding protein 1 (papbn1). According to our findings, most stable reference genes in the RV and RR were hmbs/hprt and hmbs/tbp/hprt respectively. In the IRR, six reference genes were recommended for normalization purposes; however, in view of experimental feasibility limitations, target gene expression could be normalized against the three most stable reference genes (ywhaz/pabp/hmbs) without loss of sensitivity. In all cases MnSod and Cu-ZnSod expression decreased upon long reperfusion, the former in all myocardial regions and the latter in IRR alone. trxr1 expression did not vary. Conclusions This study provides a validation of reference genes in the RV and in the anterior and posterior wall of the LV of cardiac ischemia/reperfusion model and shows that gene expression should be assessed separately in each region.
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Affiliation(s)
- Nicoletta Vesentini
- Istituto di Fisiologia Clinica, Consiglio Nazionale delle Ricerche, Pisa, Italy.
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18
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Cutler MJ, Jeyaraj D, Rosenbaum DS. Cardiac electrical remodeling in health and disease. Trends Pharmacol Sci 2011; 32:174-80. [PMID: 21316769 DOI: 10.1016/j.tips.2010.12.001] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2010] [Revised: 11/25/2010] [Accepted: 12/01/2010] [Indexed: 01/12/2023]
Abstract
Electrical remodeling of the heart takes place in response to both functional (altered electrical activation) and structural (including heart failure and myocardial infarction) stressors. These electrophysiological changes produce a substrate that is prone to malignant ventricular arrhythmias. Understanding the cellular and molecular mechanisms of electrical remodeling is important in elucidating potential therapeutic targets designed to alter maladaptive electrical remodeling. For example, altered patterns of electrical activation lead primarily to electrical remodeling, without significant structural remodeling. By contrast, secondary remodeling arises in response to a structural insult. In this article we review cardiac electrical remodeling (predominantly in the ventricle) with an emphasis on the mechanisms causing these adaptations. These mechanisms suggest novel therapeutic targets for the management or prevention of the most devastating manifestation of heart disease, sudden cardiac death (SCD).
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Affiliation(s)
- Michael J Cutler
- The Heart and Vascular Research Center, MetroHealth Campus, Case Western Reserve University, Cleveland, Ohio, USA
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19
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Wilson LD, Jennings MM, Rosenbaum DS. Point: M cells are present in the ventricular myocardium. Heart Rhythm 2011; 8:930-3. [DOI: 10.1016/j.hrthm.2011.01.026] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2010] [Accepted: 01/11/2011] [Indexed: 10/18/2022]
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20
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Counterpoint: M cells do not have a functional role in the ventricular myocardium of the intact heart. Heart Rhythm 2011; 8:934-7. [DOI: 10.1016/j.hrthm.2010.10.048] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Accepted: 10/15/2011] [Indexed: 11/18/2022]
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21
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Okada JI, Washio T, Maehara A, Momomura SI, Sugiura S, Hisada T. Transmural and apicobasal gradients in repolarization contribute to T-wave genesis in human surface ECG. Am J Physiol Heart Circ Physiol 2011; 301:H200-8. [PMID: 21460196 DOI: 10.1152/ajpheart.01241.2010] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The cellular basis of the T-wave morphology of surface ECG remains controversial in clinical cardiology. We examined the effect of action potential duration (APD) distribution on T-wave morphology using a realistic model of the human ventricle and torso. We developed a finite-element model of the ventricle consisting of ∼26 million elements, including the conduction system, each implemented with the ion current model of cardiomyocytes. This model was embedded in a torso model with distinct organ structures to obtain the standard ECG leads. The APD distribution was changed in the transmural direction by locating the M cells in either the endocardial or epicardial region. We also introduced apicobasal gradients by modifying the ion channel parameters. Both the transmural gradient (with M cells on the endocardial side) and the apicobasal gradient produced positive T waves, although a very large gradient was required for the apicobasal gradient. By contrast, T waves obtained with the transmural gradient were highly symmetric and, therefore, did not represent the true physiological state. Only combination of the transmural and the moderate apicobasal gradients produced physiological T waves in surface ECG. Positive T waves in surface ECG mainly originated from the transmural distribution of APD with M cells on the endocardial side, although the apicobasal gradient was also required to attain the physiological waveform.
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Affiliation(s)
- Jun-Ichi Okada
- #381 Environmental Bldg., Kashiwa Campus, The Univ. of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8563, Japan.
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22
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Mukherjee R, Colbath GP, Justus CD, Bruce JA, Allen CM, Hewett KW, Saul JP, Gourdie RG, Spinale FG. Spatiotemporal induction of matrix metalloproteinase-9 transcription after discrete myocardial injury. FASEB J 2010; 24:3819-28. [PMID: 20530752 DOI: 10.1096/fj.10-155531] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Radiofrequency (RF) ablation of the myocardium causes discrete sites of injury. RF scars can expand, altering the extracellular matrix (ECM) structure and the continuity of the electrical syncytium of the adjacent myocardium. Matrix metalloproteinases (MMPs), such as MMP-9, contribute to ECM remodeling. However, whether and to what degree transcriptional induction of MMP-9 occurs after myocardial RF injury and the association with electrical conduction patterns after RF injury remains unexplored. This study examined MMP-9 gene promoter (M9PROM) activation after myocardial RF injury using mice in which the M9PROM was fused to a β-galactosidase (β-gal) reporter. RF lesions (0.5-mm probe, 80°C, 30 s) were created on the left ventricular (LV) epicardium of M9PROM mice (n=62) and terminally studied at 1 h, 1 d, 3 d, 7 d, 14 d, and 28 d after RF injury. M9PROM activation was localized through β-gal staining. The RF scar area and the area of β-gal staining were measured and normalized to LV area (planimetry). RF scar size increased from 1 h post-RF-injury values by 7 d and remained higher at 28 d. M9PROM activation became evident at 3 d and peaked at 7 d. Electrical conduction was measured (potentiometric dye mapping) at 7 d after RF injury. Heterogeneities in action potentials and electrical impulse propagation coincident with M9PROM activation were observed after RF injury. For example, conduction proximal to the RF site was slower than that in the remote myocardium (0.15±0.02 vs. 0.83±0.08 mm/ms, P<0.05). Thus, a unique spatiotemporal pattern of MMP-9 transcriptional activation occurred after discrete myocardial injury, which was associated with the development of electrical heterogeneity. Therefore, these findings suggest that changes in a key determinant of extracellular matrix remodeling, in addition to changes in myocardial structure, can contribute to arrhythmogenesis around the region of myocardial injury.
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Affiliation(s)
- Rupak Mukherjee
- Division of Cardiothoracic Surgery, Medical University of South Carolina, Charleston, SC 29425, USA.
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