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Stevens TL, Coles S, Sturm AC, Hoover CA, Borzok MA, Mohler PJ, El Refaey M. Molecular Pathways and Animal Models of Arrhythmias. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2024; 1441:1057-1090. [PMID: 38884769 DOI: 10.1007/978-3-031-44087-8_67] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2024]
Abstract
Arrhythmias account for over 300,000 annual deaths in the United States, and approximately half of all deaths are associated with heart disease. Mechanisms underlying arrhythmia risk are complex; however, work in humans and animal models over the past 25 years has identified a host of molecular pathways linked with both arrhythmia substrates and triggers. This chapter will focus on select arrhythmia pathways solved by linking human clinical and genetic data with animal models.
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Affiliation(s)
- Tyler L Stevens
- The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Sara Coles
- Division of Cardiology, Department of Medicine, Duke University Medical Center, Durham, NC, USA
| | - Amy C Sturm
- Genomic Medicine Institute, 23andMe, Sunnyvale, CA, USA
| | - Catherine A Hoover
- Department of Biochemistry, Chemistry, Engineering and Physics, Commonwealth University of Pennsylvania, Mansfield, PA, USA
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, USA
| | - Maegen A Borzok
- Department of Biochemistry, Chemistry, Engineering and Physics, Commonwealth University of Pennsylvania, Mansfield, PA, USA
| | - Peter J Mohler
- The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, USA
- Department of Internal Medicine, Division of Cardiovascular Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Mona El Refaey
- The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA.
- Department of Surgery, Division of Cardiac Surgery, The Ohio State University Wexner Medical Center, Columbus, OH, USA.
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Llopis-Lorente J, Baroudi S, Koloskoff K, Mora MT, Basset M, Romero L, Benito S, Dayan F, Saiz J, Trenor B. Combining pharmacokinetic and electrophysiological models for early prediction of drug-induced arrhythmogenicity. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2023; 242:107860. [PMID: 37844488 DOI: 10.1016/j.cmpb.2023.107860] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 09/28/2023] [Accepted: 10/10/2023] [Indexed: 10/18/2023]
Abstract
BACKGROUND AND OBJECTIVE In silico methods are gaining attention for predicting drug-induced Torsade de Pointes (TdP) in different stages of drug development. However, many computational models tended not to account for inter-individual response variability due to demographic covariates, such as sex, or physiologic covariates, such as renal function, which may be crucial when predicting TdP. This study aims to compare the effects of drugs in male and female populations with normal and impaired renal function using in silico methods. METHODS Pharmacokinetic models considering sex and renal function as covariates were implemented from data published in pharmacokinetic studies. Drug effects were simulated using an electrophysiologically calibrated population of cellular models of 300 males and 300 females. The population of models was built by modifying the endocardial action potential model published by O'Hara et al. (2011) according to the experimentally measured gene expression levels of 12 ion channels. RESULTS Fifteen pharmacokinetic models for CiPA drugs were implemented and validated in this study. Eight pharmacokinetic models included the effect of renal function and four the effect of sex. The mean difference in action potential duration (APD) between male and female populations was 24.9 ms (p<0.05). Our simulations indicated that women with impaired renal function were particularly susceptible to drug-induced arrhythmias, whereas healthy men were less prone to TdP. Differences between patient groups were more pronounced for high TdP-risk drugs. The proposed in silico tool also revealed that individuals with impaired renal function, electrophysiologically simulated with hyperkalemia (extracellular potassium concentration [K+]o = 7 mM) exhibited less pronounced APD prolongation than individuals with normal potassium levels. The pharmacokinetic/electrophysiological framework was used to determine the maximum safe dose of dofetilide in different patient groups. As a proof of concept, 3D simulations were also run for dofetilide obtaining QT prolongation in accordance with previously reported clinical values. CONCLUSIONS This study presents a novel methodology that combines pharmacokinetic and electrophysiological models to incorporate the effects of sex and renal function into in silico drug simulations and highlights their impact on TdP-risk assessment. Furthermore, it may also help inform maximum dose regimens that ensure TdP-related safety in a specific sub-population of patients.
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Affiliation(s)
- Jordi Llopis-Lorente
- Centro de Investigación e Innovación en Bioingeniería (Ci(2)B), Universitat Politècnica de València, camino de Vera, s/n, 46022, Valencia, Spain
| | | | | | - Maria Teresa Mora
- Centro de Investigación e Innovación en Bioingeniería (Ci(2)B), Universitat Politècnica de València, camino de Vera, s/n, 46022, Valencia, Spain
| | | | - Lucía Romero
- Centro de Investigación e Innovación en Bioingeniería (Ci(2)B), Universitat Politècnica de València, camino de Vera, s/n, 46022, Valencia, Spain
| | | | | | - Javier Saiz
- Centro de Investigación e Innovación en Bioingeniería (Ci(2)B), Universitat Politècnica de València, camino de Vera, s/n, 46022, Valencia, Spain
| | - Beatriz Trenor
- Centro de Investigación e Innovación en Bioingeniería (Ci(2)B), Universitat Politècnica de València, camino de Vera, s/n, 46022, Valencia, Spain.
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3
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Ferreira G, Santander A, Cardozo R, Chavarría L, Domínguez L, Mujica N, Benítez M, Sastre S, Sobrevia L, Nicolson GL. Nutrigenomics of inward rectifier potassium channels. Biochim Biophys Acta Mol Basis Dis 2023:166803. [PMID: 37406972 DOI: 10.1016/j.bbadis.2023.166803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Revised: 06/27/2023] [Accepted: 06/30/2023] [Indexed: 07/07/2023]
Abstract
Inwardly rectifying potassium (Kir) channels play a key role in maintaining the resting membrane potential and supporting potassium homeostasis. There are many variants of Kir channels, which are usually tetramers in which the main subunit has two trans-membrane helices attached to two N- and C-terminal cytoplasmic tails with a pore-forming loop in between that contains the selectivity filter. These channels have domains that are strongly modulated by molecules present in nutrients found in different diets, such as phosphoinositols, polyamines and Mg2+. These molecules can impact these channels directly or indirectly, either allosterically by modulation of enzymes or via the regulation of channel expression. A particular type of these channels is coupled to cell metabolism and inhibited by ATP (KATP channels, essential for insulin release and for the pathogenesis of metabolic diseases like diabetes mellitus). Genomic changes in Kir channels have a significant impact on metabolism, such as conditioning the nutrients and electrolytes that an individual can take. Thus, the nutrigenomics of ion channels is an important emerging field in which we are attempting to understand how nutrients and diets can affect the activity and expression of ion channels and how genomic changes in such channels may be the basis for pathological conditions that limit nutrition and electrolyte intake. In this contribution we briefly review Kir channels, discuss their nutrigenomics, characterize how different components in the diet affect their function and expression, and suggest how their genomic changes lead to pathological phenotypes that affect diet and electrolyte intake.
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Affiliation(s)
- Gonzalo Ferreira
- Laboratory of Ion Channels, Biological Membranes and Cell Signaling, Dept. of Biophysics, Facultad de Medicina, CP 11800, Universidad de la Republica, Montevideo, Uruguay.
| | - Axel Santander
- Laboratory of Ion Channels, Biological Membranes and Cell Signaling, Dept. of Biophysics, Facultad de Medicina, CP 11800, Universidad de la Republica, Montevideo, Uruguay
| | - Romina Cardozo
- Laboratory of Ion Channels, Biological Membranes and Cell Signaling, Dept. of Biophysics, Facultad de Medicina, CP 11800, Universidad de la Republica, Montevideo, Uruguay
| | - Luisina Chavarría
- Laboratory of Ion Channels, Biological Membranes and Cell Signaling, Dept. of Biophysics, Facultad de Medicina, CP 11800, Universidad de la Republica, Montevideo, Uruguay
| | - Lucía Domínguez
- Laboratory of Ion Channels, Biological Membranes and Cell Signaling, Dept. of Biophysics, Facultad de Medicina, CP 11800, Universidad de la Republica, Montevideo, Uruguay
| | - Nicolás Mujica
- Laboratory of Ion Channels, Biological Membranes and Cell Signaling, Dept. of Biophysics, Facultad de Medicina, CP 11800, Universidad de la Republica, Montevideo, Uruguay
| | - Milagros Benítez
- Laboratory of Ion Channels, Biological Membranes and Cell Signaling, Dept. of Biophysics, Facultad de Medicina, CP 11800, Universidad de la Republica, Montevideo, Uruguay
| | - Santiago Sastre
- Laboratory of Ion Channels, Biological Membranes and Cell Signaling, Dept. of Biophysics, Facultad de Medicina, CP 11800, Universidad de la Republica, Montevideo, Uruguay; Centro de Investigaciones Biomédicas (CEINBIO), Universidad de la República, Montevideo CP 11800, Uruguay
| | - Luis Sobrevia
- Cellular and Molecular Physiology Laboratory (CMPL), Department of Obstetrics, Division of Obstetrics and Gynaecology, School of Medicine, Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago 8330024, Chile; Department of Physiology, Faculty of Pharmacy, Universidad de Sevilla, Seville E-41012, Spain; Medical School (Faculty of Medicine), Sao Paulo State University (UNESP), Brazil; University of Queensland, Centre for Clinical Research (UQCCR), Faculty of Medicine and Biomedical Sciences, University of Queensland, Herston, 4029, Queensland, Australia; Tecnologico de Monterrey, Eutra, The Institute for Obesity Research (IOR), School of Medicine and Health Sciences, Monterrey, Nuevo León, Mexico
| | - Garth L Nicolson
- Department of Molecular Pathology, The Institute for Molecular Medicine, Huntington Beach, CA, USA
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Árpádffy-Lovas T, Mohammed ASA, Naveed M, Koncz I, Baláti B, Bitay M, Jost N, Nagy N, Baczkó I, Virág L, Varró A. Species dependent differences in the inhibition of various potassium currents and in their effects on repolarization in cardiac ventricular muscle. Can J Physiol Pharmacol 2022; 100:880-889. [PMID: 35442802 DOI: 10.1139/cjpp-2022-0028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Even though rodents are accessible model animals, their electrophysiological properties are deeply different from that of human, making the translation of rat studies to human rather difficult. We compared the mechanisms of ventricular repolarization in various animal models to those of human by measuring cardiac ventricular action potentials from ventricular papillary muscle preparations using conventional microelectrodes, and applying selective inhibitors of various potassium transmembrane ion currents. Inhibition of the IK1 current (10 µM barium chloride) significantly prolonged rat ventricular repolarization, but only slightly prolonged it in dog, and did not affect it in human. On the contrary, IKr inhibition (50 nM dofetilide) significantly prolonged repolarization in human, rabbit, and dog, but not in rat. Inhibition of the IKur current (1 µM XEN-D0101) only prolonged rat ventricular repolarization, and had no effect in human or dog. Inhibition of the IKs (500 nM HMR-1556) and Ito currents (100 µM chromanol-293B) elicited similar effects in all investigated species. We conclude that dog ventricular preparations have the strongest, and rat ventricular preparations have the weakest translational value in cardiac electrophysiological experiments.
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Affiliation(s)
- Tamás Árpádffy-Lovas
- University of Szeged Albert Szent-Györgyi Faculty of Medicine, 37443, Department of Pharmacology and Pharmacotherapy, Szeged, Csongrád, Hungary;
| | - Aiman Saleh A Mohammed
- University of Szeged Albert Szent-Györgyi Faculty of Medicine, 37443, Department of Pharmacology and Pharmacotherapy, Szeged, Csongrád, Hungary;
| | - Muhammad Naveed
- University of Szeged Albert Szent-Györgyi Faculty of Medicine, 37443, Department of Pharmacology and Pharmacotherapy, Szeged, Csongrád, Hungary;
| | - István Koncz
- University of Szeged Albert Szent-Györgyi Faculty of Medicine, 37443, Department of Pharmacology and Pharmacotherapy, Szeged, Csongrád, Hungary;
| | - Beáta Baláti
- University of Szeged Albert Szent-Györgyi Faculty of Medicine, 37443, Department of Pharmacology and Pharmacotherapy, Szeged, Csongrád, Hungary;
| | - Miklós Bitay
- University of Szeged Albert Szent-Györgyi Faculty of Medicine, 37443, Department of Cardiac Surgery, Second Department of Internal Medicine and Cardiology Center, Szeged, Csongrád, Hungary;
| | - Norbert Jost
- University of Szeged Albert Szent-Györgyi Faculty of Medicine, 37443, Department of Pharmacology and Pharmacotherapy, Szeged, Csongrád, Hungary.,Eötvös Loránd Research Network, 579839, ELKH-SZTE Research Group of Cardiovascular Pharmacology, Szeged, Hungary, Budapest, Hungary;
| | - Norbert Nagy
- University of Szeged Albert Szent-Györgyi Faculty of Medicine, 37443, Department of Pharmacology and Pharamacotherapy, Szeged, Csongrád, Hungary.,Eötvös Loránd Research Network, 579839, ELKH-SZTE Research Group of Cardiovascular Pharmacology, Szeged, Hungary, Budapest, Hungary;
| | - István Baczkó
- University of Szeged Albert Szent-Györgyi Faculty of Medicine, 37443, Department of Pharmacology and Pharmacotherapy, Szeged, Csongrád, Hungary;
| | - László Virág
- University of Szeged Albert Szent-Györgyi Faculty of Medicine, 37443, Department of Pharmacology and Pharmacotherapy, Szeged, Csongrád, Hungary;
| | - András Varró
- University of Szeged Albert Szent-Györgyi Faculty of Medicine, 37443, Department of Pharmacology and Pharmacotherapy, Szeged, Csongrád, Hungary.,Eötvös Loránd Research Network, 579839, ELKH-SZTE Research Group of Cardiovascular Pharmacology, Budapest, Hungary;
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Zhu Y, Bai J, Lo A, Lu Y, Zhao J. Mechanisms underlying pro-arrhythmic abnormalities arising from Pitx2-induced electrical remodelling: an in silico intersubject variability study. ANNALS OF TRANSLATIONAL MEDICINE 2021; 9:106. [PMID: 33569408 PMCID: PMC7867875 DOI: 10.21037/atm-20-5660] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Background Electrical remodelling as a result of the homeodomain transcription factor 2 (Pitx2)-dependent gene regulation induces atrial fibrillation (AF) with different mechanisms. The purpose of this study was to identify Pitx2-induced changes in ionic currents that cause action potential (AP) shortening and lead to triggered activity. Methods Populations of computational atrial AP models were developed based on AP recordings from sinus rhythm (SR) and AF patients. Models in the AF population were divided into triggered and untriggered AP groups to evaluate the relationship between each ion current regulated by Pitx2 and triggered APs. Untriggered AP models were then divided into shortened and unshortened AP groups to determine which Pitx2-dependent ion currents contribute to AP shortening. Results According to the physiological range of AP biomarkers measured experimentally, populations of 2,885 SR and 4,781 AF models out of the initial pool of 30,000 models were selected. Models in the AF population predicted AP shortening and triggered activity observed in experiments in Pitx2-induced remodelling conditions. The AF models included 925 triggered AP models, 1,412 shortened AP models and 2,444 unshortened AP models. Intersubject variability in IKs and ICaL primarily modulated variability in AP duration (APD) in all shortened and unshortened AP models, whereas intersubject variability in IK1 and SERCA mainly contributed to the variability in AP morphology in all triggered and untriggered AP models. The incidence of shortened AP was positively correlated with IKs and IK1 and was negatively correlated with INa , ICaL and SERCA, whereas the incidence of triggered AP was negatively correlated with IKs and IK1 and was positively correlated with INa , ICaL and SERCA. Conclusions Electrical remodelling due to Pitx2 upregulation may increase the incidence of shortened AP, whereas electrical remodelling arising from Pitx2 downregulation may favor to the genesis of triggered AP.
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Affiliation(s)
- Yijie Zhu
- Department of Electronic Engineering, College of Information Science and Technology, Jinan University, Guangzhou, China
| | - Jieyun Bai
- Department of Electronic Engineering, College of Information Science and Technology, Jinan University, Guangzhou, China
| | - Andy Lo
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Yaosheng Lu
- Department of Electronic Engineering, College of Information Science and Technology, Jinan University, Guangzhou, China
| | - Jichao Zhao
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
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van der Pol A, Hoes MF, de Boer RA, van der Meer P. Cardiac foetal reprogramming: a tool to exploit novel treatment targets for the failing heart. J Intern Med 2020; 288:491-506. [PMID: 32557939 PMCID: PMC7687159 DOI: 10.1111/joim.13094] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 03/26/2020] [Accepted: 04/14/2020] [Indexed: 12/11/2022]
Abstract
As the heart matures during embryogenesis from its foetal stages, several structural and functional modifications take place to form the adult heart. This process of maturation is in large part due to an increased volume and work load of the heart to maintain proper circulation throughout the growing body. In recent years, it has been observed that these changes are reversed to some extent as a result of cardiac disease. The process by which this occurs has been characterized as cardiac foetal reprogramming and is defined as the suppression of adult and re-activation of a foetal genes profile in the diseased myocardium. The reasons as to why this process occurs in the diseased myocardium are unknown; however, it has been suggested to be an adaptive process to counteract deleterious events taking place during cardiac remodelling. Although still in its infancy, several studies have demonstrated that targeting foetal reprogramming in heart failure can lead to substantial improvement in cardiac functionality. This is highlighted by a recent study which found that by modulating the expression of 5-oxoprolinase (OPLAH, a novel cardiac foetal gene), cardiac function can be significantly improved in mice exposed to cardiac injury. Additionally, the utilization of angiotensin receptor neprilysin inhibitors (ARNI) has demonstrated clear benefits, providing important clinical proof that drugs that increase natriuretic peptide levels (part of the foetal gene programme) indeed improve heart failure outcomes. In this review, we will highlight the most important aspects of cardiac foetal reprogramming and will discuss whether this process is a cause or consequence of heart failure. Based on this, we will also explain how a deeper understanding of this process may result in the development of novel therapeutic strategies in heart failure.
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Affiliation(s)
- A van der Pol
- From the, Department of Cardiology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands.,Perioperative Inflammation and Infection Group, Department of Medicine, Faculty of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany
| | - M F Hoes
- From the, Department of Cardiology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
| | - R A de Boer
- From the, Department of Cardiology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
| | - P van der Meer
- From the, Department of Cardiology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
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Yang Q, Lv Q, Feng M, Liu M, Feng Y, Lin S, Yang J, Hu J. Taurine Prevents the Electrical Remodeling in Ach-CaCl 2 Induced Atrial Fibrillation in Rats. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 975 Pt 2:821-830. [PMID: 28849502 DOI: 10.1007/978-94-024-1079-2_64] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
OBJECTIVE To study the preventive actions and mechanism of taurine on the electrical remodeling in atrial fibrillation (AF) rats. METHODS Male Wistar rats were injected with the mixture of acetylcholine (Ach) (66 μg/mL)-CaCl2 (10 mg/mL) (i.v.) for 7 days to establish AF model. Taurine was administered in drinking water 1 week before or at the same time of AF model establishment. The duration of AF was monitored by recording ECG of rats during the model establishment. At the end of the experiment, left atrial appendages were cut down to measure the effective refractory period (ERP) by S1-S2 double stimulation method; atrial tissues were collected in order to detect the concentration of K+ and taurine by flame atomic absorption spectrometry and ELISA respectively; total RNA were extracted from the atrium, gene expressions of Kv1.5, Kv4.3, Kir2.1, Kir3.4 were detected by semi-quantitative RT-PCR. RESULTS Taurine administration effectively shortened the AF duration of rats and prolonged atrial ERP than the model and taurine depleted rats. In addition, atrial K+ level in taurine treated groups was significantly reduced nearly to the normal level. Moreover, the mRNA expression levels of Kir3.4 and Kv1.5 were significantly increased in the taurine preventive treated groups. CONCLUSIONS Taurine can prevent the atrial electrical remodeling and decrease the duration of AF in rats by reducing the atrial K+ concentration and up-regulating mRNA expression levels of Kir3.4 and Kv1.5.
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Affiliation(s)
- Qunhui Yang
- Liaoning Provincial Key Laboratory of Zoonosis, College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, Shenyang, Liaoning, 110866, People's Republic of China
| | - Qiufeng Lv
- Liaoning Provincial Key Laboratory of Zoonosis, College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, Shenyang, Liaoning, 110866, People's Republic of China
| | - Man Feng
- Liaoning Provincial Key Laboratory of Zoonosis, College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, Shenyang, Liaoning, 110866, People's Republic of China
| | - Mei Liu
- Liaoning Provincial Key Laboratory of Zoonosis, College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, Shenyang, Liaoning, 110866, People's Republic of China
| | - Ying Feng
- Liaoning Provincial Key Laboratory of Zoonosis, College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, Shenyang, Liaoning, 110866, People's Republic of China
| | - Shumei Lin
- Liaoning Provincial Key Laboratory of Zoonosis, College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, Shenyang, Liaoning, 110866, People's Republic of China
| | - Jiancheng Yang
- Liaoning Provincial Key Laboratory of Zoonosis, College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, Shenyang, Liaoning, 110866, People's Republic of China
| | - Jianmin Hu
- Liaoning Provincial Key Laboratory of Zoonosis, College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, Shenyang, Liaoning, 110866, People's Republic of China.
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Bruyneel AAN, McKeithan WL, Feyen DAM, Mercola M. Using iPSC Models to Probe Regulation of Cardiac Ion Channel Function. Curr Cardiol Rep 2018; 20:57. [DOI: 10.1007/s11886-018-1000-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Britton OJ, Bueno-Orovio A, Virág L, Varró A, Rodriguez B. The Electrogenic Na +/K + Pump Is a Key Determinant of Repolarization Abnormality Susceptibility in Human Ventricular Cardiomyocytes: A Population-Based Simulation Study. Front Physiol 2017; 8:278. [PMID: 28529489 PMCID: PMC5418229 DOI: 10.3389/fphys.2017.00278] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Accepted: 04/18/2017] [Indexed: 11/23/2022] Open
Abstract
Background: Cellular repolarization abnormalities occur unpredictably due to disease and drug effects, and can occur even in cardiomyocytes that exhibit normal action potentials (AP) under control conditions. Variability in ion channel densities may explain differences in this susceptibility to repolarization abnormalities. Here, we quantify the importance of key ionic mechanisms determining repolarization abnormalities following ionic block in human cardiomyocytes yielding normal APs under control conditions. Methods and Results: Sixty two AP recordings from non-diseased human heart preparations were used to construct a population of human ventricular models with normal APs and a wide range of ion channel densities. Multichannel ionic block was applied to investigate susceptibility to repolarization abnormalities. IKr block was necessary for the development of repolarization abnormalities. Models that developed repolarization abnormalities over the widest range of blocks possessed low Na+/K+ pump conductance below 50% of baseline, and ICaL conductance above 70% of baseline. Furthermore, INaK made the second largest contribution to repolarizing current in control simulations and the largest contribution under 75% IKr block. Reversing intracellular Na+ overload caused by reduced INaK was not sufficient to prevent abnormalities in models with low Na+/K+ pump conductance, while returning Na+/K+ pump conductance to normal substantially reduced abnormality occurrence, indicating INaK is an important repolarization current. Conclusions: INaK is an important determinant of repolarization abnormality susceptibility in human ventricular cardiomyocytes, through its contribution to repolarization current rather than homeostasis. While we found IKr block to be necessary for repolarization abnormalities to occur, INaK decrease, as in disease, may amplify the pro-arrhythmic risk of drug-induced IKr block in humans.
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Affiliation(s)
| | | | - László Virág
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of SzegedSzeged, Hungary
| | - András Varró
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of SzegedSzeged, Hungary
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Valsartan Attenuates KIR2.1 by Downregulating the Th1 Immune Response in Rats Following Myocardial Infarction. J Cardiovasc Pharmacol 2016; 67:252-9. [DOI: 10.1097/fjc.0000000000000341] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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Muszkiewicz A, Britton OJ, Gemmell P, Passini E, Sánchez C, Zhou X, Carusi A, Quinn TA, Burrage K, Bueno-Orovio A, Rodriguez B. Variability in cardiac electrophysiology: Using experimentally-calibrated populations of models to move beyond the single virtual physiological human paradigm. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2015; 120:115-27. [PMID: 26701222 PMCID: PMC4821179 DOI: 10.1016/j.pbiomolbio.2015.12.002] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 11/24/2015] [Accepted: 12/02/2015] [Indexed: 01/13/2023]
Abstract
Physiological variability manifests itself via differences in physiological function between individuals of the same species, and has crucial implications in disease progression and treatment. Despite its importance, physiological variability has traditionally been ignored in experimental and computational investigations due to averaging over samples from multiple individuals. Recently, modelling frameworks have been devised for studying mechanisms underlying physiological variability in cardiac electrophysiology and pro-arrhythmic risk under a variety of conditions and for several animal species as well as human. One such methodology exploits populations of cardiac cell models constrained with experimental data, or experimentally-calibrated populations of models. In this review, we outline the considerations behind constructing an experimentally-calibrated population of models and review the studies that have employed this approach to investigate variability in cardiac electrophysiology in physiological and pathological conditions, as well as under drug action. We also describe the methodology and compare it with alternative approaches for studying variability in cardiac electrophysiology, including cell-specific modelling approaches, sensitivity-analysis based methods, and populations-of-models frameworks that do not consider the experimental calibration step. We conclude with an outlook for the future, predicting the potential of new methodologies for patient-specific modelling extending beyond the single virtual physiological human paradigm.
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Affiliation(s)
- Anna Muszkiewicz
- Department of Computer Science, University of Oxford, Parks Road, Oxford OX1 3QD, United Kingdom
| | - Oliver J Britton
- Department of Computer Science, University of Oxford, Parks Road, Oxford OX1 3QD, United Kingdom
| | - Philip Gemmell
- Clyde Biosciences Ltd, West Medical Building, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Elisa Passini
- Department of Computer Science, University of Oxford, Parks Road, Oxford OX1 3QD, United Kingdom
| | - Carlos Sánchez
- Center for Computational Medicine in Cardiology (CCMC), Institute of Computational Science, Università della Svizzera italiana, Lugano, Switzerland
| | - Xin Zhou
- Department of Computer Science, University of Oxford, Parks Road, Oxford OX1 3QD, United Kingdom
| | | | - T Alexander Quinn
- Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Kevin Burrage
- Department of Computer Science, University of Oxford, Parks Road, Oxford OX1 3QD, United Kingdom; Mathematical Sciences, Queensland University of Technology, Queensland 4072, Australia; ACEMS, ARC Centre of Excellence for Mathematical and Statistical Frontiers, Queensland University of Technology, Queensland 4072, Australia
| | - Alfonso Bueno-Orovio
- Department of Computer Science, University of Oxford, Parks Road, Oxford OX1 3QD, United Kingdom
| | - Blanca Rodriguez
- Department of Computer Science, University of Oxford, Parks Road, Oxford OX1 3QD, United Kingdom.
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12
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Pasipoularides A. Mechanotransduction Mechanisms for Intraventricular Diastolic Vortex Forces and Myocardial Deformations: Part 2. J Cardiovasc Transl Res 2015; 8:293-318. [PMID: 25971844 PMCID: PMC4519381 DOI: 10.1007/s12265-015-9630-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 04/27/2015] [Indexed: 01/10/2023]
Abstract
Epigenetic mechanisms are fundamental in cardiac adaptations, remodeling, reverse remodeling, and disease. A primary goal of translational cardiovascular research is recognizing whether disease-related changes in phenotype can be averted by eliminating or reducing the effects of environmental epigenetic risks. There may be significant medical benefits in using gene-by-environment interaction knowledge to prevent or reverse organ abnormalities and disease. This survey proposes that "environmental" forces associated with diastolic RV/LV rotatory flows exert important, albeit still unappreciated, epigenetic actions influencing functional and morphological cardiac adaptations. Mechanisms analogous to Murray's law of hydrodynamic shear-induced endothelial cell modulation of vascular geometry are likely to link diastolic vortex-associated shear, torque and "squeeze" forces to RV/LV adaptations. The time has come to explore a new paradigm in which such forces play a fundamental epigenetic role, and to work out how heart cells react to them. Findings from various imaging modalities, computational fluid dynamics, molecular cell biology and cytomechanics are considered. The following are examined, among others: structural dynamics of myocardial cells (endocardium, cardiomyocytes, and fibroblasts), cytoskeleton, nucleoskeleton, and extracellular matrix; mechanotransduction and signaling; and mechanical epigenetic influences on genetic expression. To help integrate and focus relevant pluridisciplinary research, rotatory RV/LV filling flow is placed within a working context that has a cytomechanics perspective. This new frontier in cardiac research should uncover versatile mechanistic insights linking filling vortex patterns and attendant forces to variable expressions of gene regulation in RV/LV myocardium. In due course, it should reveal intrinsic homeostatic arrangements that support ventricular myocardial function and adaptability.
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Affiliation(s)
- Ares Pasipoularides
- Department of Surgery, Duke University School of Medicine, Durham, NC, 27710, USA,
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13
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Wiśniowska B, Mendyk A, Fijorek K, Polak S. Computer-based prediction of the drug proarrhythmic effect: problems, issues, known and suspected challenges. Europace 2015; 16:724-35. [PMID: 24798962 DOI: 10.1093/europace/euu009] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
It is likely that computer modelling and simulations will become an element of comprehensive cardiac safety testing. Their role would be primarily the integration and the interpretation of previously gathered data. There are still unanswered questions and issues which we list and describe below. They include sources of data used for the development of the models as well as data utilized as input information, which can come from the in vitro studies and the quantitative structure-activity relationship models. The pharmacokinetics of the drugs in question play a crucial role as their active concentration should be considered, yet the question remains where is the right place to assess it. The pharmacodynamic angle includes complications coming from multiple drugs (i.e. active metabolites) acting in parallel as well as the type of interaction with (potentially) multiple affected channels. Once established, the model and the methodology of its use should be further validated, optimistically against individual data reported at the clinical level as the physiological, anatomical, and genetic parameters play a crucial role in the drug-triggered arrhythmia induction. All the abovementioned issues should be at least considered and-hopefully-resolved, to properly utilize the mathematical models for a cardiac safety assessment.
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Affiliation(s)
- Barbara Wiśniowska
- Unit of Pharmacoepidemiology and Pharmacoeconomics, Faculty of Pharmacy, Medical College, Jagiellonian University, Medyczna 9 Street, 30-688 Kraków, Poland
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14
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Novotny T, Leinveber P, Hnatkova K, Reichlova T, Matejkova M, Sisakova M, Krejci J, Hude P, Bedanova H, Nemec P, Spinar J, Spinarova L, Malik M. Pilot study of sex differences in QTc intervals of heart transplant recipients. J Electrocardiol 2014; 47:863-8. [DOI: 10.1016/j.jelectrocard.2014.07.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Indexed: 11/30/2022]
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15
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Franconi F, Campesi I. Pharmacogenomics, pharmacokinetics and pharmacodynamics: interaction with biological differences between men and women. Br J Pharmacol 2014; 171:580-94. [PMID: 23981051 PMCID: PMC3969074 DOI: 10.1111/bph.12362] [Citation(s) in RCA: 153] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2013] [Revised: 08/05/2013] [Accepted: 08/16/2013] [Indexed: 12/16/2022] Open
Abstract
Pharmacological response depends on multiple factors and one of them is sex-gender. Data on the specific effects of sex-gender on pharmacokinetics, as well as the safety and efficacy of numerous medications, are beginning to emerge. Nevertheless, the recruitment of women for clinical research is inadequate, especially during the first phases. In general, pharmacokinetic differences between males and females are more numerous and consistent than disparities in pharmacodynamics. However, sex-gender pharmacodynamic differences are now increasingly being identified at the molecular level. It is now even becoming apparent that sex-gender influences pharmacogenomics and pharmacogenetics. Sex-related differences have been reported for several parameters, and it is consistently shown that women have a worse safety profile, with drug adverse reactions being more frequent and severe in women than in men. Overall, the pharmacological status of women is less well studied than that of men and deserves much more attention. The design of clinical and preclinical studies should have a sex-gender-based approach with the aim of tailoring therapies to an individual's needs and concerns.
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Affiliation(s)
- Flavia Franconi
- Department of Biomedical Sciences, University of SassariSassari, Italy
- Laboratory of Sex-Gender Medicine, National Institute of Biostructures and BiosystemsOsilo, Italy
| | - Ilaria Campesi
- Laboratory of Sex-Gender Medicine, National Institute of Biostructures and BiosystemsOsilo, Italy
- Department of Surgical, Microsurgical and Medical Sciences, University of SassariSassari, Italy
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16
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Jagu B, Charpentier F, Toumaniantz G. Identifying potential functional impact of mutations and polymorphisms: linking heart failure, increased risk of arrhythmias and sudden cardiac death. Front Physiol 2013; 4:254. [PMID: 24065925 PMCID: PMC3778269 DOI: 10.3389/fphys.2013.00254] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Accepted: 08/29/2013] [Indexed: 01/22/2023] Open
Abstract
Researchers and clinicians have discovered several important concepts regarding the mechanisms responsible for increased risk of arrhythmias, heart failure, and sudden cardiac death. One major step in defining the molecular basis of normal and abnormal cardiac electrical behavior has been the identification of single mutations that greatly increase the risk for arrhythmias and sudden cardiac death by changing channel-gating characteristics. Indeed, mutations in several genes encoding ion channels, such as SCN5A, which encodes the major cardiac Na+ channel, have emerged as the basis for a variety of inherited cardiac arrhythmias such as long QT syndrome, Brugada syndrome, progressive cardiac conduction disorder, sinus node dysfunction, or sudden infant death syndrome. In addition, genes encoding ion channel accessory proteins, like anchoring or chaperone proteins, which modify the expression, the regulation of endocytosis, and the degradation of ion channel a-subunits have also been reported as susceptibility genes for arrhythmic syndromes. The regulation of ion channel protein expression also depends on a fine-tuned balance among different other mechanisms, such as gene transcription, RNA processing, post-transcriptional control of gene expression by miRNA, protein synthesis, assembly and post-translational modification and trafficking. The aim of this review is to inventory, through the description of few representative examples, the role of these different biogenic mechanisms in arrhythmogenesis, HF and SCD in order to help the researcher to identify all the processes that could lead to arrhythmias. Identification of novel targets for drug intervention should result from further understanding of these fundamental mechanisms.
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Affiliation(s)
- Benoît Jagu
- INSERM, UMR1087, l'institut du thorax, IRS-UN Nantes, France ; CNRS, UMR6291 Nantes, France ; Faculté de Médecine, Université de Nantes Nantes, France
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17
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Stillitano F, Lonardo G, Giunti G, Del Lungo M, Coppini R, Spinelli V, Sartiani L, Poggesi C, Mugelli A, Cerbai E. Chronic atrial fibrillation alters the functional properties of If in the human atrium. J Cardiovasc Electrophysiol 2013; 24:1391-400. [PMID: 23869794 DOI: 10.1111/jce.12212] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2012] [Revised: 05/24/2013] [Accepted: 05/29/2013] [Indexed: 01/08/2023]
Abstract
INTRODUCTION Despite the evidence that the hyperpolarization-activated current (If) is highly modulated in human cardiomyopathies, no definite data exist in chronic atrial fibrillation (cAF). We investigated the expression, function, and modulation of If in human cAF. METHODS AND RESULTS Right atrial samples were obtained from sinus rhythm (SR, n = 49) or cAF (duration >1 year, n = 31) patients undergoing corrective cardiac surgery. Among f-channel isoforms expressed in the human atrium (HCN1, 2 and 4), HCN4 mRNA levels measured by RT-PCR were significantly reduced. However, protein expression was preserved in cAF compared to SR (+85% for HCN4); concurrently, miR-1 expression was significantly reduced. In patch-clamped atrial myocytes, current-specific conductance (gf) was significantly increased in cAF at voltages around the threshold for If activation (-60 to -80 mV); accordingly, a 10-mV rightward shift of the activation curve occurred (P < 0.01). β-Adrenergic and 5-HT4 receptor stimulation exerted similar effects on If in cAF and SR cells, while the ANP-mediated effect was significantly reduced (P < 0.02), suggesting downregulation of natriuretic peptide signaling. CONCLUSIONS In human cAF modifications in transcriptional and posttranscriptional mechanisms of HCN channels occur, associated with a slight yet significant gain-of-function of If , which may contribute to enhanced atrial ectopy.
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Affiliation(s)
- Francesca Stillitano
- Center for Molecular Medicine (C.I.M.M.B.A.), Department NEUROFARBA, University of Firenze, Florence, Italy
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18
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Xiao L, Koopmann TT, Ördög B, Postema PG, Verkerk AO, Iyer V, Sampson KJ, Boink GJJ, Mamarbachi MA, Varro A, Jordaens L, Res J, Kass RS, Wilde AA, Bezzina CR, Nattel S. Unique cardiac Purkinje fiber transient outward current β-subunit composition: a potential molecular link to idiopathic ventricular fibrillation. Circ Res 2013; 112:1310-22. [PMID: 23532596 DOI: 10.1161/circresaha.112.300227] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
RATIONALE A chromosomal haplotype producing cardiac overexpression of dipeptidyl peptidase-like protein-6 (DPP6) causes familial idiopathic ventricular fibrillation. The molecular basis of transient outward current (I(to)) in Purkinje fibers (PFs) is poorly understood. We hypothesized that DPP6 contributes to PF I(to) and that its overexpression might specifically alter PF I(to) properties and repolarization. OBJECTIVE To assess the potential role of DPP6 in PF I(to). METHODS AND RESULTS Clinical data in 5 idiopathic ventricular fibrillation patients suggested arrhythmia origin in the PF-conducting system. PF and ventricular muscle I(to) had similar density, but PF I(to) differed from ventricular muscle in having tetraethylammonium sensitivity and slower recovery. DPP6 overexpression significantly increased, whereas DPP6 knockdown reduced, I(to) density and tetraethylammonium sensitivity in canine PF but not in ventricular muscle cells. The K(+)-channel interacting β-subunit K(+)-channel interacting protein type-2, essential for normal expression of I(to) in ventricular muscle, was weakly expressed in human PFs, whereas DPP6 and frequenin (neuronal calcium sensor-1) were enriched. Heterologous expression of Kv4.3 in Chinese hamster ovary cells produced small I(to); I(to) amplitude was greatly enhanced by coexpression with K(+)-channel interacting protein type-2 or DPP6. Coexpression of DPP6 with Kv4.3 and K(+)-channel interacting protein type-2 failed to alter I(to) compared with Kv4.3/K(+)-channel interacting protein type-2 alone, but DPP6 expression with Kv4.3 and neuronal calcium sensor-1 (to mimic PF I(to) composition) greatly enhanced I(to) compared with Kv4.3/neuronal calcium sensor-1 and recapitulated characteristic PF kinetic/pharmacological properties. A mathematical model of cardiac PF action potentials showed that I(to) enhancement can greatly accelerate PF repolarization. CONCLUSIONS These results point to a previously unknown central role of DPP6 in PF I(to), with DPP6 gain of function selectively enhancing PF current, and suggest that a DPP6-mediated PF early-repolarization syndrome might be a novel molecular paradigm for some forms of idiopathic ventricular fibrillation.
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Affiliation(s)
- Ling Xiao
- Department of Medicine, Montreal Heart Institute and Université de Montréal, Montreal, QC, Canada
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19
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Walmsley J, Rodriguez JF, Mirams GR, Burrage K, Efimov IR, Rodriguez B. mRNA expression levels in failing human hearts predict cellular electrophysiological remodeling: a population-based simulation study. PLoS One 2013; 8:e56359. [PMID: 23437117 PMCID: PMC3577832 DOI: 10.1371/journal.pone.0056359] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Accepted: 01/08/2013] [Indexed: 01/06/2023] Open
Abstract
Differences in mRNA expression levels have been observed in failing versus non-failing human hearts for several membrane channel proteins and accessory subunits. These differences may play a causal role in electrophysiological changes observed in human heart failure and atrial fibrillation, such as action potential (AP) prolongation, increased AP triangulation, decreased intracellular calcium transient (CaT) magnitude and decreased CaT triangulation. Our goal is to investigate whether the information contained in mRNA measurements can be used to predict cardiac electrophysiological remodeling in heart failure using computational modeling. Using mRNA data recently obtained from failing and non-failing human hearts, we construct failing and non-failing cell populations incorporating natural variability and up/down regulation of channel conductivities. Six biomarkers are calculated for each cell in each population, at cycle lengths between 1500 ms and 300 ms. Regression analysis is performed to determine which ion channels drive biomarker variability in failing versus non-failing cardiomyocytes. Our models suggest that reported mRNA expression changes are consistent with AP prolongation, increased AP triangulation, increased CaT duration, decreased CaT triangulation and amplitude, and increased delay between AP and CaT upstrokes in the failing population. Regression analysis reveals that changes in AP biomarkers are driven primarily by reduction in I, and changes in CaT biomarkers are driven predominantly by reduction in I and SERCA. In particular, the role of I is pacing rate dependent. Additionally, alternans developed at fast pacing rates for both failing and non-failing cardiomyocytes, but the underlying mechanisms are different in control and heart failure.
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Affiliation(s)
- John Walmsley
- Department of Computer Science, University of Oxford, Oxford, United Kingdom
| | - Jose F. Rodriguez
- Aragón Institute of Engineering Research, University of Zaragoza, Zaragoza, Spain
- Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine, Zaragoza, Spain
| | - Gary R. Mirams
- Department of Computer Science, University of Oxford, Oxford, United Kingdom
| | - Kevin Burrage
- Department of Computer Science, University of Oxford, Oxford, United Kingdom
- School of Mathematical Sciences, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Igor R. Efimov
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri, United States of America
| | - Blanca Rodriguez
- Department of Computer Science, University of Oxford, Oxford, United Kingdom
- * E-mail:
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20
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Ambrosi CM, Yamada KA, Nerbonne JM, Efimov IR. Gender differences in electrophysiological gene expression in failing and non-failing human hearts. PLoS One 2013; 8:e54635. [PMID: 23355885 PMCID: PMC3552854 DOI: 10.1371/journal.pone.0054635] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2012] [Accepted: 12/13/2012] [Indexed: 12/19/2022] Open
Abstract
The increasing availability of human cardiac tissues for study are critically important in increasing our understanding of the impact of gender, age, and other parameters, such as medications and cardiac disease, on arrhythmia susceptibility. In this study, we aimed to compare the mRNA expression of 89 ion channel subunits, calcium handling proteins, and transcription factors important in cardiac conduction and arrhythmogenesis in the left atria (LA) and ventricles (LV) of failing and nonfailing human hearts of both genders. Total RNA samples, prepared from failing male (n = 9) and female (n = 7), and from nonfailing male (n = 9) and female (n = 9) hearts, were probed using custom-designed Taqman gene arrays. Analyses were performed to explore the relationships between gender, failure state, and chamber expression. Hierarchical cluster analysis revealed chamber specific expression patterns, but failed to identify disease- or gender-dependent clustering. Gender-specific analysis showed lower expression levels in transcripts encoding for Kv4.3, KChIP2, Kv1.5, and Kir3.1 in the failing female as compared with the male LA. Analysis of LV transcripts, however, did not reveal significant differences based on gender. Overall, our data highlight the differential expression and transcriptional remodeling of ion channel subunits in the human heart as a function of gender and cardiac disease. Furthermore, the availability of such data sets will allow for the development of disease-, gender-, and, most importantly, patient-specific cardiac models, with the ability to utilize such information as mRNA expression to predict cardiac phenotype.
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Affiliation(s)
- Christina M. Ambrosi
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri, United States of America
| | - Kathryn A. Yamada
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Jeanne M. Nerbonne
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Igor R. Efimov
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri, United States of America
- * E-mail:
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21
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Vedantham V, Evangelista M, Huang Y, Srivastava D. Spatiotemporal regulation of an Hcn4 enhancer defines a role for Mef2c and HDACs in cardiac electrical patterning. Dev Biol 2012; 373:149-62. [PMID: 23085412 DOI: 10.1016/j.ydbio.2012.10.017] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Revised: 10/11/2012] [Accepted: 10/12/2012] [Indexed: 11/17/2022]
Abstract
Regional differences in cardiomyocyte automaticity permit the sinoatrial node (SAN) to function as the leading cardiac pacemaker and the atrioventricular (AV) junction as a subsidiary pacemaker. The regulatory mechanisms controlling the distribution of automaticity within the heart are not understood. To understand regional variation in cardiac automaticity, we carried out an in vivo analysis of cis-regulatory elements that control expression of the hyperpolarization-activated cyclic-nucleotide gated ion channel 4 (Hcn4). Using transgenic mice, we found that spatial and temporal patterning of Hcn4 expression in the AV conduction system required cis-regulatory elements with multiple conserved fragments. One highly conserved region, which contained a myocyte enhancer factor 2C (Mef2C) binding site previously described in vitro, induced reporter expression specifically in the embryonic non-chamber myocardium and the postnatal AV bundle in a Mef2c-dependent manner in vivo. Inhibition of histone deacetylase (HDAC) activity in cultured transgenic embryos showed expansion of reporter activity to working myocardium. In adult animals, hypertrophy induced by transverse aortic constriction, which causes translocation of HDACs out of the nucleus, resulted in ectopic activation of the Hcn4 enhancer in working myocardium, recapitulating pathological electrical remodeling. These findings reveal mechanisms that control the distribution of automaticity among cardiomyocytes during development and in response to stress.
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Affiliation(s)
- Vasanth Vedantham
- Gladstone Institute of Cardiovascular Disease, University of California, San Francisco, CA 94158, USA.
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22
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Partemi S, Batlle M, Berne P, Berruezo A, Campos B, Mont L, Riuró H, Roig E, Pérez-Villa F, Ortiz J, Pascali VL, Oliva A, Brugada R, Brugada J. Analysis of the arrhythmogenic substrate in human heart failure. Cardiovasc Pathol 2012; 22:133-40. [PMID: 23036686 DOI: 10.1016/j.carpath.2012.07.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Revised: 07/26/2012] [Accepted: 07/26/2012] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND The mechanism of sudden cardiac death in patients with heart failure (HF) is uncertain. Both electrical instability and structural remodelling could be factors that lead to fatal arrhythmias. We sought to analyse the expression of the sodium (SCN5A) and potassium (KCND3) channels as well as the fibrosis content in the ventricles of human HF and of non-diseased hearts under different post-mortem intervals. METHODS AND RESULTS We analysed normal human hearts as controls [n=20 for the right ventricle (RV) and n=13 for the left ventricle (LV)] and human hearts from HF patients, which were obtained at the time of cardiac transplantation, as cases (n=48 for RV and n=34 for LV). Transcription of the SCN5A (probes SCN5A E4-5, E11-12, and E28) and KCND3 channels and of COLLAGEN I and III were assayed by real-time polymerase chain reaction. In addition, paraffin sections were used to analyse the percentage of collagen deposition in both cases and controls. KCND3 mRNA expression in the LV was lower in the cases than in controls (P<.001). Higher levels of SCN5A mRNA were found in the HF samples when analysed with probe SCN5A E4-5 (P<.05). SCN5A expression was lower in the controls with longer post-mortem interval (n=4) than in the controls with a shorter post- mortem interval (n=16, P<.01). KCND3 mRNA levels were also different between the two control groups (P<.05). Collagen deposition was higher in the LV tissues of the cases when compared to controls (P<.001), and it was higher in the LV from HF patients than in the RV (P<.05). Furthermore, collagen deposition was higher in the LV samples from patients with implanted cardiac defibrillator (ICD) therapy than in the LV of patients with no ICD therapy (P<.05). CONCLUSIONS These data indicate that ionic and structural remodelling could be pathophysiological mechanisms of cardiac arrhythmias in HF patients.
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Affiliation(s)
- Sara Partemi
- Thorax Institute-Hospital Clínic, University of Barcelona (Cardiology Department) Institute of Biomedical Research August Pi iSunyer (IDIBAPS), Spain.
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23
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Yang PC, Clancy CE. In silico Prediction of Sex-Based Differences in Human Susceptibility to Cardiac Ventricular Tachyarrhythmias. Front Physiol 2012; 3:360. [PMID: 23049511 PMCID: PMC3442371 DOI: 10.3389/fphys.2012.00360] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2012] [Accepted: 08/22/2012] [Indexed: 11/13/2022] Open
Abstract
Sex-based differences in human susceptibility to cardiac ventricular tachyarrhythmias likely result from the emergent effects of multiple intersecting processes that fundamentally differ in male and female hearts. Included are measured differences in the genes encoding key cardiac ion channels and effects of sex steroid hormones to acutely modify electrical activity. At the genome-scale, human females have recently been shown to have lower expression of genes encoding key cardiac repolarizing potassium currents and connexin43, the primary ventricular gap-junction subunit. Human males and females also have distinct sex steroid hormones. Here, we developed mathematical models for male and female ventricular human heart cells by incorporating experimentally determined genomic differences and effects of sex steroid hormones into the O'Hara-Rudy model. These "male" and "female" model cells and tissues then were used to predict how various sex-based differences underlie arrhythmia risk. Genomic-based differences in ion channel expression were alone sufficient to determine longer female cardiac action potential durations (APD) in both epicardial and endocardial cells compared to males. Subsequent addition of sex steroid hormones exacerbated these differences, as testosterone further shortened APDs, while estrogen and progesterone application resulted in disparate effects on APDs. Our results indicate that incorporation of experimentally determined genomic differences from human hearts in conjunction with sex steroid hormones are consistent with clinically observed differences in QT interval, T-wave shape and morphology, and critically, in the higher vulnerability of adult human females to Torsades de Pointes type arrhythmias. The model suggests that female susceptibility to alternans stems from longer female action potentials, while reentrant arrhythmia derives largely from sex-based differences in conduction play an important role in arrhythmia vulnerability.
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Affiliation(s)
- Pei-Chi Yang
- Department of Pharmacology, University of California Davis, CA, USA
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24
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Refaat MM, Tanaka T, Kormos RL, McNamara D, Teuteberg J, Winowich S, London B, Simon MA. Survival benefit of implantable cardioverter-defibrillators in left ventricular assist device-supported heart failure patients. J Card Fail 2011; 18:140-5. [PMID: 22300782 DOI: 10.1016/j.cardfail.2011.10.020] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2011] [Revised: 10/20/2011] [Accepted: 10/25/2011] [Indexed: 01/30/2023]
Abstract
BACKGROUND Implantable cardioverter-defibrillators (ICDs) reduce mortality in heart failure (HF). In patients requiring a ventricular assist device (VAD), the benefit from ICD therapy is not well established. The aim of this study was to define the impact of ICD on outcomes in VAD-supported patients. METHODS AND RESULTS We reviewed data for consecutive adult HF patients receiving VAD as a bridge to transplantation from 1996 to 2003. The primary outcome was survival to transplantation. A total of 144 VADs were implanted [85 left ventricular (LVAD), 59 biventricular (BIVAD), mean age 50 ± 12 years, 77% male, left ventricular ejection fraction 18 ± 9%, 54% ischemic]. Mean length of support was 119 days (range 1-670); 103 patients (72%) survived to transplantation. Forty-five patients had an ICD (33 LVAD, 12 BIVAD). More LVAD patients had an appropriate ICD shock before implantation than after (16 vs 7; P = .02). There was a trend toward higher shock frequency before LVAD implant than after (3.3 ± 5.2 vs 1.1 ± 3.8 shocks/y; P = .06). Mean time to first shock after VAD implant was 129 ± 109 days. LVAD-supported patients with an ICD were significantly more likely to survive to transplantation [1-y actuarial survival to transplantation: LVAD: 91% with ICD vs 57% without ICD (log-rank P = .01); BIVAD: 54% vs 47% (log-rank P = NS)]. An ICD was associated with significantly increased survival in a multivariate model controlling for confounding variables (odds ratio 2.54, 95% confidence interval 1.04-6.21; P = .04). CONCLUSIONS Shock frequency decreases after VAD implantation, likely owing to ventricular unloading, but appropriate ICD shocks still occur in 21% of patients. An ICD is associated with improved survival in LVAD-supported HF patients.
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Affiliation(s)
- Marwan M Refaat
- Division of Cardiology, University of California, San Francisco, California
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25
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Limberg SH, Netter MF, Rolfes C, Rinné S, Schlichthörl G, Zuzarte M, Vassiliou T, Moosdorf R, Wulf H, Daut J, Sachse FB, Decher N. TASK-1 channels may modulate action potential duration of human atrial cardiomyocytes. Cell Physiol Biochem 2011; 28:613-24. [PMID: 22178873 DOI: 10.1159/000335757] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/28/2011] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND/AIMS Atrial fibrillation is the most common arrhythmia in the elderly, and potassium channels with atrium-specific expression have been discussed as targets to treat atrial fibrillation. Our aim was to characterize TASK-1 channels in human heart and to functionally describe the role of the atrial whole cell current I(TASK-1). METHODS AND RESULTS Using quantitative PCR, we show that TASK-1 is predominantly expressed in the atria, auricles and atrio-ventricular node of the human heart. Single channel recordings show the functional expression of TASK-1 in right human auricles. In addition, we describe for the first time the whole cell current carried by TASK-1 channels (I(TASK-1)) in human atrial tissue. We show that I(TASK-1) contributes to the sustained outward current I(Ksus) and that I(TASK-1) is a major component of the background conductance in human atrial cardiomyocytes. Using patch clamp recordings and mathematical modeling of action potentials, we demonstrate that modulation of I(TASK-1) can alter human atrial action potential duration. CONCLUSION Due to the lack of ventricular expression and the ability to alter human atrial action potential duration, TASK-1 might be a drug target for the treatment of atrial fibrillation.
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Affiliation(s)
- Sven H Limberg
- Institut für Physiologie und Pathophysiologie, Abteilung vegetative Physiologie, Universität Marburg, Deutschhausstraße 1-2, Marburg, Germany
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Xu L, Chen J, Li XY, Ren S, Huang CX, Wu G, Li XY, Jiang XJ. Analysis of Na(+)/Ca (2+) exchanger (NCX) function and current in murine cardiac myocytes during heart failure. Mol Biol Rep 2011; 39:3847-52. [PMID: 21750914 DOI: 10.1007/s11033-011-1163-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2011] [Accepted: 06/30/2011] [Indexed: 11/29/2022]
Abstract
Na(+)/Ca(2+) exchanger (NCX) plays important roles in cardiac electrical activity and calcium homeostasis. NCX current (I(NCX)) shows transmural gradient across left ventricle in many species. Previous studies demonstrated that NCX expression was increased and transmural gradient of I(NCX) was disrupted in failing heart, but the mechanisms underlying I(NCX) remodeling still remain unknown. In present study, we used patch clamp technique to record I(NCX) from subepicardial (EPI) myocytes and subendocardial (ENDO) myocytes isolated from sham operation (SO) mice and heart failure (HF) mice. Our results showed that I(NCX) was higher in normal EPI cells compared with that in ENDO, whatever for forward mode or reverse mode. In HF group, I(NCX) was significantly up-regulated, but EPI-ENDO difference was disrupted because of a more increase of I(NCX) in ENDO myocytes. In order to explore the molecular mechanism underlying remodeling of I(NCX) in failing heart, we detected the protein expression of NCX1 and Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) by Western blot. We found that CaMKII activity was dramatically enhanced and parallel with the expression of NCX1 in failing heart. Our study demonstrated that transmural gradient of I(NCX) existed in murine left ventricle, and increased activity of CaMKII should account for I(NCX) remodeling in failing heart.
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Affiliation(s)
- Lin Xu
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, 430060, People's Republic of China.
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Naud P, Guasch E, Nattel S. Physiological versus pathological cardiac electrical remodelling: potential basis and relevance to clinical management. J Physiol 2010; 588:4855-6. [PMID: 21173087 PMCID: PMC3020321 DOI: 10.1113/jphysiol.2010.202556] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Affiliation(s)
- Patrice Naud
- Department of Medicine and Research Center, Montreal Heart Institute and Université de Montréal.
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Benito B, Guasch E, Rivard L, Nattel S. Clinical and mechanistic issues in early repolarization of normal variants and lethal arrhythmia syndromes. J Am Coll Cardiol 2010; 56:1177-86. [PMID: 20883924 DOI: 10.1016/j.jacc.2010.05.037] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2010] [Revised: 05/20/2010] [Accepted: 05/25/2010] [Indexed: 11/17/2022]
Abstract
Early repolarization, involving ST-segment elevation and, sometimes, prominent J waves at the QRS-ST junction, has been considered a normal electrocardiographic variant for over 60 years. A growing number of case reports and case-control studies indicate that in some instances, early repolarization patterns are associated with increased risk of idiopathic ventricular fibrillation. Epidemiological evidence indicates a dose effect for the risk of cardiac and sudden death with the extent of J-point elevation. This paper reviews present knowledge regarding the epidemiology, presentation, therapeutic response, and mechanisms characteristic of early repolarization. We highlight major unanswered questions relating to our limited ability to determine which individuals with this common electrocardiographic variant are at risk for sudden death, our incomplete understanding of underlying mechanisms, the inadequate information regarding genetic determinants and therapeutic responses, and the unclear relationship between early repolarization and other conditions involving accelerated repolarization and sudden arrhythmic death such as Brugada and short-QT syndromes. This review paper intends to inform the practicing physician about important clinical issues and to stimulate investigators to address the many unresolved questions in this rapidly evolving field.
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Affiliation(s)
- Begoña Benito
- Research Center and Department of Medicine, Montreal Heart Institute and Université de Montréal, Montreal, Quebec, Canada
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