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Horváth B, Kovács Z, Dienes C, Barta Z, Óvári J, Szentandrássy N, Magyar J, Bányász T, Nánási PP. Relationship between ion currents and membrane capacitance in canine ventricular myocytes. Sci Rep 2024; 14:11241. [PMID: 38755246 PMCID: PMC11099174 DOI: 10.1038/s41598-024-61736-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Accepted: 05/09/2024] [Indexed: 05/18/2024] Open
Abstract
Current density, the membrane current value divided by membrane capacitance (Cm), is widely used in cellular electrophysiology. Comparing current densities obtained in different cell populations assume that Cm and ion current magnitudes are linearly related, however data is scarce about this in cardiomyocytes. Therefore, we statistically analyzed the distributions, and the relationship between parameters of canine cardiac ion currents and Cm, and tested if dividing original parameters with Cm had any effect. Under conventional voltage clamp conditions, correlations were high for IK1, moderate for IKr and ICa,L, while negligible for IKs. Correlation between Ito1 peak amplitude and Cm was negligible when analyzing all cells together, however, the analysis showed high correlations when cells of subepicardial, subendocardial or midmyocardial origin were analyzed separately. In action potential voltage clamp experiments IK1, IKr and ICa,L parameters showed high correlations with Cm. For INCX, INa,late and IKs there were low-to-moderate correlations between Cm and these current parameters. Dividing the original current parameters with Cm reduced both the coefficient of variation, and the deviation from normal distribution. The level of correlation between ion currents and Cm varies depending on the ion current studied. This must be considered when evaluating ion current densities in cardiac cells.
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Affiliation(s)
- Balázs Horváth
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.
- Faculty of Pharmacy, University of Debrecen, Debrecen, Hungary.
| | - Zsigmond Kovács
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Csaba Dienes
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Zalán Barta
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - József Óvári
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Norbert Szentandrássy
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- Department of Basic Medical Sciences, Faculty of Dentistry, University of Debrecen, Debrecen, Hungary
| | - János Magyar
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- Division of Sport Physiology, Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Tamás Bányász
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Péter P Nánási
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- Department of Dental Physiology and Pharmacology, Faculty of Dentistry, University of Debrecen, Debrecen, Hungary
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2
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Fullerton KE, Clark AP, Krogh-Madsen T, Christini DJ. Optimization of a cardiomyocyte model illuminates role of increased INa,L in repolarization reserve. Am J Physiol Heart Circ Physiol 2024; 326:H334-H345. [PMID: 38038718 DOI: 10.1152/ajpheart.00553.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 11/15/2023] [Accepted: 11/19/2023] [Indexed: 12/02/2023]
Abstract
Cardiac ion currents may compensate for each other when one is compromised by a congenital or drug-induced defect. Such redundancy contributes to a robust repolarization reserve that can prevent the development of lethal arrhythmias. Most efforts made to describe this phenomenon have quantified contributions by individual ion currents. However, it is important to understand the interplay between all major ion-channel conductances, as repolarization reserve is dependent on the balance between all ion currents in a cardiomyocyte. Here, a genetic algorithm was designed to derive profiles of nine ion-channel conductances that optimize repolarization reserve in a mathematical cardiomyocyte model. Repolarization reserve was quantified using a previously defined metric, repolarization reserve current, i.e., the minimum constant current to prevent normal action potential repolarization in a cell. The optimization improved repolarization reserve current up to 84% compared to baseline in a human adult ventricular myocyte model and increased resistance to arrhythmogenic insult. The optimized conductance profiles were not only characterized by increased repolarizing current conductances but also uncovered a previously unreported behavior by the late sodium current. Simulations demonstrated that upregulated late sodium increased action potential duration, without compromising repolarization reserve current. The finding was generalized to multiple models. Ultimately, this computational approach, in which multiple currents were studied simultaneously, illuminated mechanistic insights into how the metric's magnitude could be increased and allowed for the unexpected role of late sodium to be elucidated.NEW & NOTEWORTHY Genetic algorithms are typically used to fit models or extract desired parameters from data. Here, we use the tool to produce a ventricular cardiomyocyte model with increased repolarization reserve. Since arrhythmia mitigation is dependent on multiple cardiac ion-channel conductances, study using a comprehensive, unbiased, and systems-level approach is important. The use of this optimization strategy allowed us to find robust profiles that illuminated unexpected mechanistic determinants of key ion-channel conductances in repolarization reserve.
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Affiliation(s)
- Kristin E Fullerton
- Physiology, Biophysics and Systems Biology Program, Weill Cornell Graduate School of Medical Sciences, New York, New York, United States
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, New York, United States
| | - Alexander P Clark
- Department of Biomedical Engineering, Cornell University, Ithaca, New York, United States
| | - Trine Krogh-Madsen
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, New York, United States
- Institute for Computational Biomedicine, Weill Cornell Medicine, New York, New York, United States
| | - David J Christini
- Department of Physiology and Pharmacology, SUNY Downstate Health Sciences University, Brooklyn, New York, United States
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3
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Heitmann S, Vandenberg JI, Hill AP. Assessing drug safety by identifying the axis of arrhythmia in cardiomyocyte electrophysiology. eLife 2023; 12:RP90027. [PMID: 38079357 PMCID: PMC10712948 DOI: 10.7554/elife.90027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2023] Open
Abstract
Many classes of drugs can induce fatal cardiac arrhythmias by disrupting the electrophysiology of cardiomyocytes. Safety guidelines thus require all new drugs to be assessed for pro-arrhythmic risk prior to conducting human trials. The standard safety protocols primarily focus on drug blockade of the delayed-rectifier potassium current (IKr). Yet the risk is better assessed using four key ion currents (IKr, ICaL, INaL, IKs). We simulated 100,000 phenotypically diverse cardiomyocytes to identify the underlying relationship between the blockade of those currents and the emergence of ectopic beats in the action potential. We call that relationship the axis of arrhythmia. It serves as a yardstick for quantifying the arrhythmogenic risk of any drug from its profile of multi-channel block alone. We tested it on 109 drugs and found that it predicted the clinical risk labels with an accuracy of 88.1-90.8%. Pharmacologists can use our method to assess the safety of novel drugs without resorting to animal testing or unwieldy computer simulations.
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Affiliation(s)
| | - Jamie I Vandenberg
- Victor Chang Cardiac Research InstituteDarlinghurstAustralia
- School of Clinical Medicine, Faculty of Medicine and Health, University of New South WalesSydneyAustralia
| | - Adam P Hill
- Victor Chang Cardiac Research InstituteDarlinghurstAustralia
- School of Clinical Medicine, Faculty of Medicine and Health, University of New South WalesSydneyAustralia
- Victor Chang Cardiac Research Institute Innovation CentreDarlinghurstAustralia
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4
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Venkateshappa R, Hunter DV, Muralidharan P, Nagalingam RS, Huen G, Faizi S, Luthra S, Lin E, Cheng YM, Hughes J, Khelifi R, Dhunna DP, Johal R, Sergeev V, Shafaattalab S, Julian LM, Poburko DT, Laksman Z, Tibbits GF, Claydon TW. Targeted activation of human ether-à-go-go-related gene channels rescues electrical instability induced by the R56Q+/- long QT syndrome variant. Cardiovasc Res 2023; 119:2522-2535. [PMID: 37739930 PMCID: PMC10676460 DOI: 10.1093/cvr/cvad155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 06/22/2023] [Accepted: 07/10/2023] [Indexed: 09/24/2023] Open
Abstract
AIMS Long QT syndrome type 2 (LQTS2) is associated with inherited variants in the cardiac human ether-à-go-go-related gene (hERG) K+ channel. However, the pathogenicity of hERG channel gene variants is often uncertain. Using CRISPR-Cas9 gene-edited hiPSC-derived cardiomyocytes (hiPSC-CMs), we investigated the pathogenic mechanism underlying the LQTS-associated hERG R56Q variant and its phenotypic rescue by using the Type 1 hERG activator, RPR260243. METHODS AND RESULTS The above approaches enable characterization of the unclear causative mechanism of arrhythmia in the R56Q variant (an N-terminal PAS domain mutation that primarily accelerates channel deactivation) and translational investigation of the potential for targeted pharmacologic manipulation of hERG deactivation. Using perforated patch clamp electrophysiology of single hiPSC-CMs, programmed electrical stimulation showed that the hERG R56Q variant does not significantly alter the mean action potential duration (APD90). However, the R56Q variant increases the beat-to-beat variability in APD90 during pacing at constant cycle lengths, enhances the variance of APD90 during rate transitions, and increases the incidence of 2:1 block. During paired S1-S2 stimulations measuring electrical restitution properties, the R56Q variant was also found to increase the variability in rise time and duration of the response to premature stimulations. Application of the hERG channel activator, RPR260243, reduces the APD variance in hERG R56Q hiPSC-CMs, reduces the variability in responses to premature stimulations, and increases the post-repolarization refractoriness. CONCLUSION Based on our findings, we propose that the hERG R56Q variant leads to heterogeneous APD dynamics, which could result in spatial dispersion of repolarization and increased risk for re-entry without significantly affecting the average APD90. Furthermore, our data highlight the antiarrhythmic potential of targeted slowing of hERG deactivation gating, which we demonstrate increases protection against premature action potentials and reduces electrical heterogeneity in hiPSC-CMs.
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Affiliation(s)
- Ravichandra Venkateshappa
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6
| | - Diana V Hunter
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6
| | - Priya Muralidharan
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6
| | - Raghu S Nagalingam
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6
- Cellular and Regenerative Medicine Centre, British Columbia Children’s Hospital Research Institute, 938 W 28th Ave, Vancouver, BC, Canada V5Z 4H4
| | - Galvin Huen
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6
| | - Shoaib Faizi
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6
| | - Shreya Luthra
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6
| | - Eric Lin
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6
| | - Yen May Cheng
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6
| | - Julia Hughes
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6
| | - Rania Khelifi
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6
| | - Daman Parduman Dhunna
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6
| | - Raj Johal
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6
| | - Valentine Sergeev
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6
| | - Sanam Shafaattalab
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6
| | - Lisa M Julian
- Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6
| | - Damon T Poburko
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6
| | - Zachary Laksman
- Department of Medicine, School of Biomedical Engineering, University of British Columbia, 2194 Health Sciences Mall, Vancouver, BC, Canada V6T 1Z3
| | - Glen F Tibbits
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6
- Cellular and Regenerative Medicine Centre, British Columbia Children’s Hospital Research Institute, 938 W 28th Ave, Vancouver, BC, Canada V5Z 4H4
- Department of Molecular Biology and Biochemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6
| | - Tom W Claydon
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6
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5
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Jameson MB, Ríos-Pérez EB, Liu F, Eichel CA, Robertson GA. Pairwise biosynthesis of ion channels stabilizes excitability and mitigates arrhythmias. Proc Natl Acad Sci U S A 2023; 120:e2305295120. [PMID: 37816059 PMCID: PMC10589643 DOI: 10.1073/pnas.2305295120] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 08/14/2023] [Indexed: 10/12/2023] Open
Abstract
Coordinated expression of ion channels is crucial for cardiac rhythms, neural signaling, and cell cycle progression. Perturbation of this balance results in many disorders including cardiac arrhythmias. Prior work revealed association of mRNAs encoding cardiac NaV1.5 (SCN5A) and hERG1 (KCNH2), but the functional significance of this association was not established. Here, we provide a more comprehensive picture of KCNH2, SCN5A, CACNA1C, and KCNQ1 transcripts collectively copurifying with nascent hERG1, NaV1.5, CaV1.2, or KCNQ1 channel proteins. Single-molecule fluorescence in situ hybridization (smFISH) combined with immunofluorescence reveals that the channel proteins are synthesized predominantly as heterotypic pairs from discrete molecules of mRNA, not as larger cotranslational complexes. Puromycin disrupted colocalization of mRNA with its encoded protein, as expected, but remarkably also pairwise mRNA association, suggesting that transcript association relies on intact translational machinery or the presence of the nascent protein. Targeted depletion of KCHN2 by specific shRNA resulted in concomitant reduction of all associated mRNAs, with a corresponding reduction in the encoded channel currents. This co-knockdown effect, originally described for KCNH2 and SCN5A, thus appears to be a general phenomenon among transcripts encoding functionally related proteins. In multielectrode array recordings, proarrhythmic behavior arose when IKr was reduced by the selective blocker dofetilide at IC50 concentrations, but not when equivalent reductions were mediated by shRNA, suggesting that co-knockdown mitigates proarrhythmic behavior expected from the selective reduction of a single channel species. We propose that coordinated, cotranslational association of functionally related ion channel mRNAs confers electrical stability by co-regulating complementary ion channels in macromolecular complexes.
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Affiliation(s)
- Margaret B. Jameson
- Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI53705
| | - Erick B. Ríos-Pérez
- Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI53705
| | - Fang Liu
- Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI53705
| | - Catherine A. Eichel
- Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI53705
| | - Gail A. Robertson
- Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI53705
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6
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Shi S, Mao X, Lv J, Wang Y, Zhang X, Shou X, Zhang B, Li Y, Wu H, Song Q, Hu Y. Qi-Po-Sheng-Mai granule ameliorates Ach-CaCl 2 -induced atrial fibrillation by regulating calcium homeostasis in cardiomyocytes. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2023; 119:155017. [PMID: 37597360 DOI: 10.1016/j.phymed.2023.155017] [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: 04/06/2023] [Revised: 07/15/2023] [Accepted: 08/06/2023] [Indexed: 08/21/2023]
Abstract
BACKGROUND Atrial fibrillation (AF) is one of the most common arrhythmias encountered in clinical settings. Currently, the pathophysiology of AF remains unclear, which severely limits the effectiveness and safety of medical therapies. The Chinese herbal formula Qi-Po-Sheng-Mai Granule (QPSM) has been widely used in China to treat AF. However, its pharmacological and molecular mechanisms remain unknown. PURPOSE The purpose of this study was to investigate the molecular mechanisms and potential targets of QPSM for AF. STUDY DESIGN AND METHODS The AF model was induced by Ach (66 μg/ml) and CaCl2 (10 mg/kg), and the dose of 0.1 ml/100 g was injected into the tail vein for 5 weeks. QPSM was administered daily at doses of 4.42 and 8.84 g/kg, and amiodarone (0.18 g/kg) was used as the positive control. The effect of QPSM on AF was assessed by electrocardiogram, echocardiography, and histopathological analysis. Then, we employed network pharmacology with single nucleus RNA sequencing (snRNA-Seq) to investigate the molecular mechanisms and potential targets of QPSM for AF. Furthermore, high performance liquid chromatography (HPLC) method was used for component analysis of QPSM, and molecular docking was used to verify the potential targets. Using the IonOptix single cell contraction and ion synchronization test equipment, single myocyte length and calcium ion variations were observed in real time. The expression levels of calcium Transporter-related proteins were detected by western blot and immunohistochemistry. RESULTS Based on an Ach-CaCl2-induced AF model, we found that QPSM treatment significantly reduced atrial electrical remodeling-related markers, such as AF inducibility and duration, and attenuated atrial dilation and fibrosis. Network pharmacology identified 52 active ingredients and 119 potential targets for QPSM in the treatment of AF, and 45 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were enriched, among which calcium pathway had the greatest impact. Using single nucleus sequencing (snRNA-seq), we identified cardiomyocytes as the most differentially expressed in response to drug treatment, with nine differentially expressed genes enriched in calcium signaling pathways. High performance liquid chromatography and molecular docking confirmed that the core components of QPSM strongly bind to the key factors in the calcium signaling pathway. Additional experiments have shown that QPSM increases calcium transients (CaT) and contractility in the individual cardiomyocyte. This was accomplished by increasing the expression of CACNA1C and SERCA2a and decreasing the expression of CAMK2B and NCX1. CONCLUSION The present study has systematically elucidated the role of QPSM in maintaining calcium homeostasis in cardiomyocytes through the regulation of calcium transporters, which could lead to new drug development ideas for AF.
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Affiliation(s)
- Shuqing Shi
- Department of Internal Medicine, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, 5 Beixiange Street Xicheng District, Beijing 100053, China
| | - Xinxin Mao
- Department of Internal Medicine, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, 5 Beixiange Street Xicheng District, Beijing 100053, China
| | - Jiayu Lv
- Department of Internal Medicine, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, 5 Beixiange Street Xicheng District, Beijing 100053, China
| | - Yajiao Wang
- Department of Internal Medicine, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, 5 Beixiange Street Xicheng District, Beijing 100053, China
| | - Xuesong Zhang
- Department of Cardiovascular, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing, China
| | - Xintian Shou
- China Academy of Chinese Medical Sciences, Beijing, China
| | - Bingxuan Zhang
- Department of Internal Medicine, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, 5 Beixiange Street Xicheng District, Beijing 100053, China
| | - Yumeng Li
- Department of Internal Medicine, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, 5 Beixiange Street Xicheng District, Beijing 100053, China
| | - Huaqin Wu
- Department of Cardiovascular, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing, China
| | - Qingqiao Song
- Department of Internal Medicine, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, 5 Beixiange Street Xicheng District, Beijing 100053, China.
| | - Yuanhui Hu
- Department of Cardiovascular, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing, China.
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7
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Grandi E, Navedo MF, Saucerman JJ, Bers DM, Chiamvimonvat N, Dixon RE, Dobrev D, Gomez AM, Harraz OF, Hegyi B, Jones DK, Krogh-Madsen T, Murfee WL, Nystoriak MA, Posnack NG, Ripplinger CM, Veeraraghavan R, Weinberg S. Diversity of cells and signals in the cardiovascular system. J Physiol 2023; 601:2547-2592. [PMID: 36744541 PMCID: PMC10313794 DOI: 10.1113/jp284011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Accepted: 01/19/2023] [Indexed: 02/07/2023] Open
Abstract
This white paper is the outcome of the seventh UC Davis Cardiovascular Research Symposium on Systems Approach to Understanding Cardiovascular Disease and Arrhythmia. This biannual meeting aims to bring together leading experts in subfields of cardiovascular biomedicine to focus on topics of importance to the field. The theme of the 2022 Symposium was 'Cell Diversity in the Cardiovascular System, cell-autonomous and cell-cell signalling'. Experts in the field contributed their experimental and mathematical modelling perspectives and discussed emerging questions, controversies, and challenges in examining cell and signal diversity, co-ordination and interrelationships involved in cardiovascular function. This paper originates from the topics of formal presentations and informal discussions from the Symposium, which aimed to develop a holistic view of how the multiple cell types in the cardiovascular system integrate to influence cardiovascular function, disease progression and therapeutic strategies. The first section describes the major cell types (e.g. cardiomyocytes, vascular smooth muscle and endothelial cells, fibroblasts, neurons, immune cells, etc.) and the signals involved in cardiovascular function. The second section emphasizes the complexity at the subcellular, cellular and system levels in the context of cardiovascular development, ageing and disease. Finally, the third section surveys the technological innovations that allow the interrogation of this diversity and advancing our understanding of the integrated cardiovascular function and dysfunction.
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Affiliation(s)
- Eleonora Grandi
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - Manuel F. Navedo
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - Jeffrey J. Saucerman
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA
| | - Donald M. Bers
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - Nipavan Chiamvimonvat
- Department of Pharmacology, University of California Davis, Davis, CA, USA
- Department of Internal Medicine, University of California Davis, Davis, CA, USA
| | - Rose E. Dixon
- Department of Physiology and Membrane Biology, University of California Davis, Davis, CA, USA
| | - Dobromir Dobrev
- Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Essen, Germany
- Department of Medicine, Montreal Heart Institute and Université de Montréal, Montréal, Canada
- Department of Molecular Physiology & Biophysics, Baylor College of Medicine, Houston, TX, USA
| | - Ana M. Gomez
- Signaling and Cardiovascular Pathophysiology-UMR-S 1180, INSERM, Université Paris-Saclay, Orsay, France
| | - Osama F. Harraz
- Department of Pharmacology, Larner College of Medicine, and Vermont Center for Cardiovascular and Brain Health, University of Vermont, Burlington, VT, USA
| | - Bence Hegyi
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - David K. Jones
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI, USA
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Trine Krogh-Madsen
- Department of Physiology & Biophysics, Weill Cornell Medicine, New York, New York, USA
| | - Walter Lee Murfee
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL, USA
| | - Matthew A. Nystoriak
- Department of Medicine, Division of Environmental Medicine, Center for Cardiometabolic Science, University of Louisville, Louisville, KY, 40202, USA
| | - Nikki G. Posnack
- Department of Pediatrics, Department of Pharmacology and Physiology, The George Washington University, Washington, DC, USA
- Sheikh Zayed Institute for Pediatric and Surgical Innovation, Children’s National Heart Institute, Children’s National Hospital, Washington, DC, USA
| | | | - Rengasayee Veeraraghavan
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, USA
- Dorothy M. Davis Heart & Lung Research Institute, The Ohio State University – Wexner Medical Center, Columbus, OH, USA
| | - Seth Weinberg
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, USA
- Dorothy M. Davis Heart & Lung Research Institute, The Ohio State University – Wexner Medical Center, Columbus, OH, USA
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8
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Alexander C, Bishop MJ, Gilchrist RJ, Burton FL, Smith GL, Myles RC. Initiation of ventricular arrhythmia in the acquired long QT syndrome. Cardiovasc Res 2023; 119:465-476. [PMID: 35727943 PMCID: PMC10064840 DOI: 10.1093/cvr/cvac103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 04/25/2022] [Accepted: 06/02/2022] [Indexed: 11/15/2022] Open
Abstract
AIMS Long QT syndrome (LQTS) carries a risk of life-threatening polymorphic ventricular tachycardia (Torsades de Pointes, TdP) and is a major cause of premature sudden cardiac death. TdP is induced by R-on-T premature ventricular complexes (PVCs), thought to be generated by cellular early-afterdepolarisations (EADs). However, EADs in tissue require cellular synchronisation, and their role in TdP induction remains unclear. We aimed to determine the mechanism of TdP induction in rabbit hearts with acquired LQTS (aLQTS). METHODS AND RESULTS Optical mapping of action potentials (APs) and intracellular Ca2+ was performed in Langendorff-perfused rabbit hearts (n = 17). TdP induced by R-on-T PVCs was observed during aLQTS (50% K+/Mg++ & E4031) conditions in all hearts (P < 0.0001 vs. control). Islands of AP prolongation bounded by steep voltage gradients (VGs) were consistently observed before arrhythmia and peak VGs were more closely related to the PVC upstroke than EADs, both temporally (7 ± 5 ms vs. 44 ± 27 ms, P < 0.0001) and spatially (1.0 ± 0.7 vs. 3.6 ± 0.9 mm, P < 0.0001). PVCs were initiated at estimated voltages of ∼ -40 mV and had upstroke dF/dtmax and Vm-Ca2+ dynamics compatible with ICaL activation. Computational simulations demonstrated that PVCs could arise directly from VGs, through electrotonic triggering of ICaL. In experiments and the model, sub-maximal L-type Ca2+ channel (LTCC) block (200 nM nifedipine and 90% gCaL, respectively) abolished both PVCs and TdP in the continued presence of aLQTS. CONCLUSION These data demonstrate that ICaL activation at sites displaying steep VGs generates the PVCs which induce TdP, providing a mechanism and rationale for LTCC blockers as a novel therapeutic approach in LQTS.
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Affiliation(s)
- Cherry Alexander
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Martin J Bishop
- School of Biomedical Engineering and Imaging Sciences, King’s College London, St Thomas' Hospital, Westminster Bridge Road, London SE1 7EH, UK
| | - Rebecca J Gilchrist
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Francis L Burton
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Godfrey L Smith
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Rachel C Myles
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
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9
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Miller JA, Moise N, Weinberg SH. Modeling incomplete penetrance in long QT syndrome type 3 through ion channel heterogeneity: an in silico population study. Am J Physiol Heart Circ Physiol 2023; 324:H179-H197. [PMID: 36487185 PMCID: PMC10072004 DOI: 10.1152/ajpheart.00430.2022] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Revised: 11/16/2022] [Accepted: 11/29/2022] [Indexed: 12/14/2022]
Abstract
Many cardiac diseases are characterized by an increased late sodium current, including heart failure, hypertrophic cardiomyopathy, and inherited long QT syndrome type 3 (LQT3). The late sodium current in LQT3 is caused by a gain-of-function mutation in the voltage-gated sodium channel Nav1.5. Despite a well-defined genetic cause of LQT3, treatment remains inconsistent because of incomplete penetrance of the mutation and variability of antiarrhythmic efficacy. Here, we investigate the relationship between LQT3-associated mutation incomplete penetrance and variability in ion channel expression, simulating a population of 1,000 individuals with the O'Hara-Rudy model of the human ventricular myocyte. We first simulate healthy electrical activity (i.e., in the absence of a mutation) and then incorporate heterozygous expression for three LQT3-associated mutations (Y1795C, I1768V, and ΔKPQ), to directly compare the effects of each mutation on individuals across a diverse population. For all mutations, we find that susceptibility, defined by either the presence of an early afterdepolarization (EAD) or prolonged action potential duration (APD), primarily depends on the balance between the conductance of IKr and INa, for which individuals with a higher IKr-to-INa ratio are less susceptible. Furthermore, we find distinct differences across the population, observing individuals susceptible to zero, one, two, or all three mutations. Individuals tend to be less susceptible with an appropriate balance of repolarizing currents, typically via increased IKs or IK1. Interestingly, the more critical repolarizing current is mutation specific. We conclude that the balance between key currents plays a significant role in mutant-specific presentation of the disease phenotype in LQT3.NEW & NOTEWORTHY An in silico population approach investigates the relationship between variability in ion channel expression and gain-of-function mutations in the voltage-gated sodium channel associated with the congenital disorder long QT syndrome type 3 (LQT3). We find that ion channel variability can contribute to incomplete penetrance of the mutation, with mutant-specific differences in ion channel conductances leading to susceptibility to proarrhythmic action potential duration prolongation or early afterdepolarizations.
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Affiliation(s)
- Jacob A Miller
- Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio
| | - Nicolae Moise
- Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio
| | - Seth H Weinberg
- Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio
- Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, Ohio
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10
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Stavrou MR, So SS, Finch AM, Ballouz S, Smith NJ. Gene expression analyses of TAS1R taste receptors relevant to the treatment of cardiometabolic disease. Chem Senses 2023; 48:bjad027. [PMID: 37539767 DOI: 10.1093/chemse/bjad027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Indexed: 08/05/2023] Open
Abstract
The sweet taste receptor (STR) is a G protein-coupled receptor (GPCR) responsible for mediating cellular responses to sweet stimuli. Early evidence suggests that elements of the STR signaling system are present beyond the tongue in metabolically active tissues, where it may act as an extraoral glucose sensor. This study aimed to delineate expression of the STR in extraoral tissues using publicly available RNA-sequencing repositories. Gene expression data was mined for all genes implicated in the structure and function of the STR, and control genes including highly expressed metabolic genes in relevant tissues, other GPCRs and effector G proteins with physiological roles in metabolism, and other GPCRs with expression exclusively outside the metabolic tissues. Since the physiological role of the STR in extraoral tissues is likely related to glucose sensing, expression was then examined in diseases related to glucose-sensing impairment such as type 2 diabetes. An aggregate co-expression network was then generated to precisely determine co-expression patterns among the STR genes in these tissues. We found that STR gene expression was negligible in human pancreatic and adipose tissues, and low in intestinal tissue. Genes encoding the STR did not show significant co-expression or connectivity with other functional genes in these tissues. In addition, STR expression was higher in mouse pancreatic and adipose tissues, and equivalent to human in intestinal tissue. Our results suggest that STR expression in mice is not representative of expression in humans, and the receptor is unlikely to be a promising extraoral target in human cardiometabolic disease.
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Affiliation(s)
- Mariah R Stavrou
- Orphan Receptor Laboratory, School of Biomedical Sciences, Faculty of Medicine and Health, UNSW Sydney, Sydney, NSW, Australia
| | - Sean Souchiart So
- Orphan Receptor Laboratory, School of Biomedical Sciences, Faculty of Medicine and Health, UNSW Sydney, Sydney, NSW, Australia
| | - Angela M Finch
- Department of Pharmacology, School of Biomedical Sciences, Faculty of Medicine and Health, UNSW Sydney, Sydney, NSW, Australia
| | - Sara Ballouz
- Garvan-Weizmann Centre for Cellular Genomics, Garvan Institute of Medical Research, Sydney, NSW, Australia
- School of Computer Science and Engineering, Faculty of Engineering, UNSW Sydney, Sydney, NSW, Australia
| | - Nicola J Smith
- Orphan Receptor Laboratory, School of Biomedical Sciences, Faculty of Medicine and Health, UNSW Sydney, Sydney, NSW, Australia
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11
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Lachaud Q, Aziz MHN, Burton FL, Macquaide N, Myles RC, Simitev RD, Smith GL. Electrophysiological heterogeneity in large populations of rabbit ventricular cardiomyocytes. Cardiovasc Res 2022; 118:3112-3125. [PMID: 35020837 PMCID: PMC9732512 DOI: 10.1093/cvr/cvab375] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 01/07/2022] [Indexed: 01/01/2023] Open
Abstract
AIMS Cardiac electrophysiological heterogeneity includes: (i) regional differences in action potential (AP) waveform, (ii) AP waveform differences in cells isolated from a single region, (iii) variability of the contribution of individual ion currents in cells with similar AP durations (APDs). The aim of this study is to assess intra-regional AP waveform differences, to quantify the contribution of specific ion channels to the APD via drug responses and to generate a population of mathematical models to investigate the mechanisms underlying heterogeneity in rabbit ventricular cells. METHODS AND RESULTS APD in ∼50 isolated cells from subregions of the LV free wall of rabbit hearts were measured using a voltage-sensitive dye. When stimulated at 2 Hz, average APD90 value in cells from the basal epicardial region was 254 ± 25 ms (mean ± standard deviation) in 17 hearts with a mean interquartile range (IQR) of 53 ± 17 ms. Endo-epicardial and apical-basal APD90 differences accounted for ∼10% of the IQR value. Highly variable changes in APD occurred after IK(r) or ICa(L) block that included a sub-population of cells (HR) with an exaggerated (hyper) response to IK(r) inhibition. A set of 4471 AP models matching the experimental APD90 distribution was generated from a larger population of models created by random variation of the maximum conductances (Gmax) of 8 key ion channels/exchangers/pumps. This set reproduced the pattern of cell-specific responses to ICa(L) and IK(r) block, including the HR sub-population. The models exhibited a wide range of Gmax values with constrained relationships linking ICa(L) with IK(r), ICl, INCX, and INaK. CONCLUSION Modelling the measured range of inter-cell APDs required a larger range of key Gmax values indicating that ventricular tissue has considerable inter-cell variation in channel/pump/exchanger activity. AP morphology is retained by relationships linking specific ionic conductances. These interrelationships are necessary for stable repolarization despite large inter-cell variation of individual conductances and this explains the variable sensitivity to ion channel block.
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Affiliation(s)
- Quentin Lachaud
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, UK
| | - Muhamad Hifzhudin Noor Aziz
- School of Mathematics and Statistics, University of Glasgow, Glasgow, UK
- Institute of Mathematical Sciences, Faculty of Science, University of Malaya, Kuala Lumpur, Malaysia
| | - Francis L Burton
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, UK
| | - Niall Macquaide
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, UK
- School of Health and Life Sciences, Glasgow Caledonian University, Glasgow, UK
| | - Rachel C Myles
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, UK
| | - Radostin D Simitev
- School of Mathematics and Statistics, University of Glasgow, Glasgow, UK
| | - Godfrey L Smith
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, UK
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12
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Pressler MP, Horvath A, Entcheva E. Sex-dependent transcription of cardiac electrophysiology and links to acetylation modifiers based on the GTEx database. Front Cardiovasc Med 2022; 9:941890. [PMID: 35935618 PMCID: PMC9354462 DOI: 10.3389/fcvm.2022.941890] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Accepted: 06/29/2022] [Indexed: 11/30/2022] Open
Abstract
Development of safer drugs based on epigenetic modifiers, e.g., histone deacetylase inhibitors (HDACi), requires better understanding of their effects on cardiac electrophysiology. Using RNAseq data from the genotype-tissue-expression database (GTEx), we created models that link the abundance of acetylation enzymes (HDAC/SIRT/HATs), and the gene expression of ion channels (IC) via select cardiac transcription factors (TFs) in male and female adult human hearts (left ventricle, LV). Gene expression data (transcripts per million, TPM) from GTEx donors (21–70 y.o.) were filtered, normalized and transformed to Euclidian space to allow quantitative comparisons in 84 female and 158 male LVs. Sex-specific partial least-square (PLS) regression models, linking gene expression data for HDAC/SIRT/HATs to TFs and to ICs gene expression, revealed tight co-regulation of cardiac ion channels by HDAC/SIRT/HATs, with stronger clustering in the male LV. Co-regulation of genes encoding excitatory and inhibitory processes in cardiac tissue by the acetylation modifiers may help explain their predominantly net-neutral effects on cardiac electrophysiology. ATP1A1, encoding for the Na/K pump, represented an outlier—with orthogonal regulation by the acetylation modifiers to most of the ICs. The HDAC/SIRT/HAT effects were mediated by strong (+) TF regulators of ICs, e.g., MEF2A and TBX5, in both sexes. Furthermore, for male hearts, PLS models revealed a stronger (+/-) mediatory role on ICs for NKX25 and TGF1B/KLF4, respectively, while RUNX1 exhibited larger (-) TF effects on ICs in females. Male-trained PLS models of HDAC/SIRT/HAT effects on ICs underestimated the effects on some ICs in females. Insights from the GTEx dataset about the co-expression and transcriptional co-regulation of acetylation-modifying enzymes, transcription factors and key cardiac ion channels in a sex-specific manner can help inform safer drug design.
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Affiliation(s)
- Michael P. Pressler
- Department of Biomedical Engineering, George Washington University, Washington, DC, United States
| | - Anelia Horvath
- Department of Biochemistry and Molecular Medicine, McCormick Genomics and Proteomics Center, School of Medicine and Health Sciences, The George Washington University, Washington, DC, United States
| | - Emilia Entcheva
- Department of Biomedical Engineering, George Washington University, Washington, DC, United States
- *Correspondence: Emilia Entcheva,
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13
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TeBay C, McArthur JR, Mangala M, Kerr N, Heitmann S, Perry MD, Windley MJ, Vandenberg JI, Hill AP. Pathophysiological metabolic changes associated with disease modify the proarrhythmic risk profile of drugs with potential to prolong repolarisation. Br J Pharmacol 2021; 179:2631-2646. [PMID: 34837219 DOI: 10.1111/bph.15757] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Revised: 11/16/2021] [Accepted: 11/18/2021] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND AND PURPOSE Hydroxychloroquine, chloroquine and azithromycin are three drugs that were proposed to treat COVID-19. While concern already existed around their proarrhythmic potential there is little data regarding how altered physiological states encountered in patients such as febrile state, electrolyte imbalances or acidosis might change their risk profiles. EXPERIMENTAL APPROACH Potency of hERG block was measured using high-throughput electrophysiology in the presence of variable environmental factors. These potencies informed simulations to predict population risk profiles. Effects on cardiac repolarisation were verified in human induced pluripotent stem cell-derived cardiomyocytes from multiple individuals. KEY RESULTS Chloroquine and hydroxychloroquine blocked hERG with IC50 of 1.47±0.07 μM and 3.78±0.17 μM respectively, indicating proarrhythmic risk at concentrations effective against SARS-CoV-2 in vitro. Hypokalaemia and hypermagnesemia increased potency of chloroquine and hydroxychloroquine, indicating increased proarrhythmic risk. Acidosis significantly reduced potency of all drugs, whereas increased temperature decreased potency of chloroquine and hydroxychloroquine against hERG but increased potency for azithromycin. In silico simulations demonstrated that proarrhythmic risk was increased by female sex, hypokalaemia and heart failure, and identified specific genetic backgrounds associated with emergence of arrhythmia. CONCLUSION AND IMPLICATIONS Our study demonstrates how proarrhythmic risk can be exacerbated by metabolic changes and pre-existing disease. More broadly, the study acts as a blueprint for how high-throughput in vitro screening, combined with in silico simulations can help guide both preclinical screening and clinical management of patients in relation to drugs with potential to prolong repolarisation.
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Affiliation(s)
- Clifford TeBay
- Victor Chang Cardiac Research Institute, Sydney, Australia
| | - Jeffrey R McArthur
- Victor Chang Cardiac Research Institute, Sydney, Australia.,Illawarra Health and Medical Research Institute, University of Wollongong, Australia
| | - Melissa Mangala
- Victor Chang Cardiac Research Institute, Sydney, Australia.,St. Vincent's Clinical school, UNSW Sydney, Sydney, Australia
| | - Nicholas Kerr
- Victor Chang Cardiac Research Institute, Sydney, Australia.,St. Vincent's Clinical school, UNSW Sydney, Sydney, Australia
| | | | - Matthew D Perry
- Victor Chang Cardiac Research Institute, Sydney, Australia.,School of Medical Sciences, UNSW Sydney, Sydney, Australia
| | - Monique J Windley
- Victor Chang Cardiac Research Institute, Sydney, Australia.,St. Vincent's Clinical school, UNSW Sydney, Sydney, Australia
| | - Jamie I Vandenberg
- Victor Chang Cardiac Research Institute, Sydney, Australia.,St. Vincent's Clinical school, UNSW Sydney, Sydney, Australia
| | - Adam P Hill
- Victor Chang Cardiac Research Institute, Sydney, Australia.,St. Vincent's Clinical school, UNSW Sydney, Sydney, Australia
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14
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Heijman J, Sutanto H, Crijns HJGM, Nattel S, Trayanova NA. Computational models of atrial fibrillation: achievements, challenges, and perspectives for improving clinical care. Cardiovasc Res 2021; 117:1682-1699. [PMID: 33890620 PMCID: PMC8208751 DOI: 10.1093/cvr/cvab138] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Indexed: 12/11/2022] Open
Abstract
Despite significant advances in its detection, understanding and management, atrial fibrillation (AF) remains a highly prevalent cardiac arrhythmia with a major impact on morbidity and mortality of millions of patients. AF results from complex, dynamic interactions between risk factors and comorbidities that induce diverse atrial remodelling processes. Atrial remodelling increases AF vulnerability and persistence, while promoting disease progression. The variability in presentation and wide range of mechanisms involved in initiation, maintenance and progression of AF, as well as its associated adverse outcomes, make the early identification of causal factors modifiable with therapeutic interventions challenging, likely contributing to suboptimal efficacy of current AF management. Computational modelling facilitates the multilevel integration of multiple datasets and offers new opportunities for mechanistic understanding, risk prediction and personalized therapy. Mathematical simulations of cardiac electrophysiology have been around for 60 years and are being increasingly used to improve our understanding of AF mechanisms and guide AF therapy. This narrative review focuses on the emerging and future applications of computational modelling in AF management. We summarize clinical challenges that may benefit from computational modelling, provide an overview of the different in silico approaches that are available together with their notable achievements, and discuss the major limitations that hinder the routine clinical application of these approaches. Finally, future perspectives are addressed. With the rapid progress in electronic technologies including computing, clinical applications of computational modelling are advancing rapidly. We expect that their application will progressively increase in prominence, especially if their added value can be demonstrated in clinical trials.
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Affiliation(s)
- Jordi Heijman
- Department of Cardiology, Cardiovascular Research Institute Maastricht, Faculty of Health, Medicine, and Life Sciences, Maastricht University, PO Box 616, 6200 MD Maastricht, The Netherlands
| | - Henry Sutanto
- Department of Cardiology, Cardiovascular Research Institute Maastricht, Faculty of Health, Medicine, and Life Sciences, Maastricht University, PO Box 616, 6200 MD Maastricht, The Netherlands
| | - Harry J G M Crijns
- Department of Cardiology, Cardiovascular Research Institute Maastricht, Faculty of Health, Medicine, and Life Sciences, Maastricht University, PO Box 616, 6200 MD Maastricht, The Netherlands
| | - Stanley Nattel
- Department of Medicine, Montreal Heart Institute and Université de Montréal, Montreal, Canada
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Canada
- Institute of Pharmacology, West German Heart and Vascular Center, Faculty of Medicine, University Duisburg-Essen, Duisburg, Germany
- IHU Liryc and Fondation Bordeaux Université, Bordeaux, France
| | - Natalia A Trayanova
- Alliance for Cardiovascular Diagnostic and Treatment Innovation, and Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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15
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Ion current profiles in canine ventricular myocytes obtained by the "onion peeling" technique. J Mol Cell Cardiol 2021; 158:153-162. [PMID: 34089737 DOI: 10.1016/j.yjmcc.2021.05.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 05/05/2021] [Accepted: 05/21/2021] [Indexed: 02/07/2023]
Abstract
The profiles of ion currents during the cardiac action potential can be visualized by the action potential voltage clamp technique. To obtain multiple ion current data from the same cell, the "onion peeling" technique, based on sequential pharmacological dissection of ion currents, has to be applied. Combination of the two methods allows recording of several ion current profiles from the same myocyte under largely physiological conditions. Using this approach, we have studied the densities and integrals of the major cardiac inward (ICa, INCX, INa-late) and outward (IKr, IKs, IK1) currents in canine ventricular cells and studied the correlation between them. For this purpose, canine ventricular cardiomyocytes were chosen because their electrophysiological properties are similar to those of human ones. Significant positive correlation was observed between the density and integral of ICa and IKr, and positive correlation was found also between the integral of ICa and INCX. No further correlations were detected. The Ca2+-sensitivity of K+ currents was studied by comparing their parameters in the case of normal calcium homeostasis and following blockade of ICa. Out of the three K+ currents studied, only IKs was Ca2+-sensitive. The density and integral of IKs was significantly greater, while its time-to-peak value was shorter at normal Ca2+ cycling than following ICa blockade. No differences were detected for IKr or IK1 in this regard. Present results indicate that the positive correlation between ICa and IKr prominently contribute to the balance between inward and outward fluxes during the action potential plateau in canine myocytes. The results also suggest that the profiles of cardiac ion currents have to be studied under physiological conditions, since their behavior may strongly be influenced by the intracellular Ca2+ homeostasis and the applied membrane potential protocol.
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Network Pharmacology-Based Systematic Analysis of Molecular Mechanisms of Dingji Fumai Decoction for Ventricular Arrhythmia. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2021; 2021:5535480. [PMID: 34046076 PMCID: PMC8128550 DOI: 10.1155/2021/5535480] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 03/31/2021] [Accepted: 04/28/2021] [Indexed: 12/19/2022]
Abstract
Background Dingji Fumai Decoction (DFD), a traditional herbal mixture, has been widely used to ventricular arrhythmia (VA) in clinical practice in China. However, research on the bioactive components and underlying mechanisms of DFD in VA is still scarce. Methods Components of DFD were collected from TCMSP, ETCM, and literature. The chemical structures of each component were obtained from PubChem. Next, SwissADME and SwissTargetPrediction were applied for compounds screening and targets prediction of DFD; meanwhile, targets of VA were collected from DrugBank and Online Mendelian Inheritance in Man (OMIM). Then, the H-C-T-D network and the protein-protein interaction (PPI) network were constructed based on the data obtained above. CytoNCA was utilized to filter hub genes and VarElect was used to analyze the relationship between genes and diseases. At last, Metascape was employed for systematic analysis on the potential targets of herbals against VA, and AutoDock was applied for molecular docking to verify the results. Results A total of 434 components were collected, 168 of which were qualified, and there were 28 shared targets between DFD and VA. Three function modules of DFD were found from the PPI network. Further systematic analysis of shared genes and function modules explained the potential mechanism of DFD in the treatment of VA; molecular docking has verified the interactions. Conclusions DFD could be employed for VA through mechanisms, including complex interactions between related components and targets, as predicted by network pharmacology and molecular docking. This work confirmed that DFD could apply to the treatment of VA and promoted the explanation of DFD for VA in the molecular mechanisms.
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