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Tsuji Y, Yamazaki M, Shimojo M, Yanagisawa S, Inden Y, Murohara T. Mechanisms of torsades de pointes: an update. Front Cardiovasc Med 2024; 11:1363848. [PMID: 38504714 PMCID: PMC10948600 DOI: 10.3389/fcvm.2024.1363848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2023] [Accepted: 02/19/2024] [Indexed: 03/21/2024] Open
Abstract
Torsades de Pointes (TdP) refers to a polymorphic ventricular tachycardia (VT) with undulating QRS axis that occurs in long QT syndrome (LQTS), although the term has been used to describe polymorphic ventricular tachyarrhythmias in which QT intervals are not prolonged, such as short-coupled variant of TdP currently known as short-coupled ventricular fibrillation (VF) and Brugada syndrome. Extensive works on LQTS-related TdP over more than 50 years since it was first recognized by Dessertennes who coined the French term meaning "twisting of the points", have led to current understanding of the electrophysiological mechanism that TdP is initiated by triggered activity due to early afterdepolarization (EAD) and maintained by reentry within a substrate of inhomogeneous repolarization. While a recently emerging notion that steep voltage gradients rather than EADs are crucial to generate premature ventricular contractions provides additions to the initiation mode, the research to elucidate the maintenance mechanism hasn't made much progress. The reentrant activity that produces the specific form of VT is not well characterized. We have conducted optical mapping in a rabbit model of electrical storm by electrical remodeling (QT prolongation) due to chronic complete atrioventricular block and demonstrated that a tissue-island with prolonged refractoriness due to enhanced late Na+ current (INa-L) contributes to the generation of drifting rotors in a unique manner, which may explain the ECG characteristic of TdP. Moreover, we have proposed that the neural Na+ channel NaV1.8-mediated INa-L may be a new player to form the substrate for TdP. Here we discuss TdP mechanisms by comparing the findings in electrical storm rabbits with recently published studies by others in simulation models and human and animal models of LQTS.
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Affiliation(s)
- Yukiomi Tsuji
- Departments of Cardiovascular Research and Innovation, Cardiology and Advanced Cardiovascular Therapeutics, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Masatoshi Yamazaki
- Department of Cardiology, Nagano Hospital, Soja and Medical Device Development and Regulation Research Center and Department of Precision Engineering, The University of Tokyo, Tokyo, Japan
| | - Masafumi Shimojo
- Departments of Cardiovascular Research and Innovation, Cardiology and Advanced Cardiovascular Therapeutics, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Satoshi Yanagisawa
- Departments of Cardiovascular Research and Innovation, Cardiology and Advanced Cardiovascular Therapeutics, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Yasuya Inden
- Departments of Cardiovascular Research and Innovation, Cardiology and Advanced Cardiovascular Therapeutics, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Toyoaki Murohara
- Departments of Cardiovascular Research and Innovation, Cardiology and Advanced Cardiovascular Therapeutics, Nagoya University Graduate School of Medicine, Nagoya, Japan
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2
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Sharma AK, Singh S, Bhat M, Gill K, Zaid M, Kumar S, Shakya A, Tantray J, Jose D, Gupta R, Yangzom T, Sharma RK, Sahu SK, Rathore G, Chandolia P, Singh M, Mishra A, Raj S, Gupta A, Agarwal M, Kifayat S, Gupta A, Gupta P, Vashist A, Vaibhav P, Kathuria N, Yadav V, Singh RP, Garg A. New drug discovery of cardiac anti-arrhythmic drugs: insights in animal models. Sci Rep 2023; 13:16420. [PMID: 37775650 PMCID: PMC10541452 DOI: 10.1038/s41598-023-41942-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Accepted: 09/04/2023] [Indexed: 10/01/2023] Open
Abstract
Cardiac rhythm regulated by micro-macroscopic structures of heart. Pacemaker abnormalities or disruptions in electrical conduction, lead to arrhythmic disorders may be benign, typical, threatening, ultimately fatal, occurs in clinical practice, patients on digitalis, anaesthesia or acute myocardial infarction. Both traditional and genetic animal models are: In-vitro: Isolated ventricular Myocytes, Guinea pig papillary muscles, Patch-Clamp Experiments, Porcine Atrial Myocytes, Guinea pig ventricular myocytes, Guinea pig papillary muscle: action potential and refractory period, Langendorff technique, Arrhythmia by acetylcholine or potassium. Acquired arrhythmia disorders: Transverse Aortic Constriction, Myocardial Ischemia, Complete Heart Block and AV Node Ablation, Chronic Tachypacing, Inflammation, Metabolic and Drug-Induced Arrhythmia. In-Vivo: Chemically induced arrhythmia: Aconitine antagonism, Digoxin-induced arrhythmia, Strophanthin/ouabain-induced arrhythmia, Adrenaline-induced arrhythmia, and Calcium-induced arrhythmia. Electrically induced arrhythmia: Ventricular fibrillation electrical threshold, Arrhythmia through programmed electrical stimulation, sudden coronary death in dogs, Exercise ventricular fibrillation. Genetic Arrhythmia: Channelopathies, Calcium Release Deficiency Syndrome, Long QT Syndrome, Short QT Syndrome, Brugada Syndrome. Genetic with Structural Heart Disease: Arrhythmogenic Right Ventricular Cardiomyopathy/Dysplasia, Dilated Cardiomyopathy, Hypertrophic Cardiomyopathy, Atrial Fibrillation, Sick Sinus Syndrome, Atrioventricular Block, Preexcitation Syndrome. Arrhythmia in Pluripotent Stem Cell Cardiomyocytes. Conclusion: Both traditional and genetic, experimental models of cardiac arrhythmias' characteristics and significance help in development of new antiarrhythmic drugs.
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Affiliation(s)
- Ashish Kumar Sharma
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India.
| | - Shivam Singh
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Mehvish Bhat
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Kartik Gill
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Mohammad Zaid
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Sachin Kumar
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Anjali Shakya
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Junaid Tantray
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Divyamol Jose
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Rashmi Gupta
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Tsering Yangzom
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Rajesh Kumar Sharma
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | | | - Gulshan Rathore
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Priyanka Chandolia
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Mithilesh Singh
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Anurag Mishra
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Shobhit Raj
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Archita Gupta
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Mohit Agarwal
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Sumaiya Kifayat
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Anamika Gupta
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Prashant Gupta
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Ankit Vashist
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Parth Vaibhav
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Nancy Kathuria
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Vipin Yadav
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Ravindra Pal Singh
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Arun Garg
- MVN University, Palwal, Haryana, India
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3
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Benson JM, Wang G, Hutt JA, Wu G, Kaminsky SM, Cram S, Barur R, Donahue JK. Preclinical safety and biodistribution assessment of Ad-KCNH2-G628S administered via atrial painting in New Zealand white rabbits. Basic Clin Pharmacol Toxicol 2023; 133:179-193. [PMID: 37177881 PMCID: PMC10935599 DOI: 10.1111/bcpt.13885] [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: 10/26/2022] [Revised: 04/27/2023] [Accepted: 05/02/2023] [Indexed: 05/15/2023]
Abstract
Post-operative atrial fibrillation (POAF) is the most common complication after cardiac surgery. Despite implementation of several pharmacological strategies, incidence of POAF remains at approximately 30%. An adenovirus vector encoding KCNH2-G628S has proven efficacious in a porcine model of AF. In this preclinical study, 1.5 × 1010 or 1.5 × 1012 Ad-KCNH2-G628S vector particles (vp) were applied to the atrial epicardium or 1.5 × 1012 vp were applied to the whole epicardial surface of New Zealand White rabbits. Saline and vector vehicle served as procedure controls. Animals were followed for up to 42 days. Vector genomes persisted in the atria up to 42 days, with no distribution to extra-thoracic organs. There were no adverse effects attributable to test article on standard toxicological endpoints or on blood pressure, left atrial or ventricular ejection fractions, electrocardiographic parameters, or serum IL-6 or troponin concentrations. Mononuclear infiltration of the myocardium of the atrial free walls of low-dose, but not high-dose animals was observed at 7 and 21 days, but these changes did not persist or affect cardiac function. After scaling for heart size, results indicate the test article is safe at doses up to 25 times the maximum proposed for the human clinical trial.
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Affiliation(s)
- Janet M. Benson
- Applied Toxicology Program, Lovelace Biomedical Research Institute, Albuquerque, NM 87108, USA
| | - Gensheng Wang
- Applied Toxicology Program, Lovelace Biomedical Research Institute, Albuquerque, NM 87108, USA
- Baxter International, Inc. Deerfield, IL 60015, USA
| | - Julie A. Hutt
- Greenfield Pathology Services, Inc., Greenfield, IN 46140, USA
| | - Guodong Wu
- Applied Toxicology Program, Lovelace Biomedical Research Institute, Albuquerque, NM 87108, USA
| | - Stephen M. Kaminsky
- Weill Cornell Medicine, Belfer Gene Therapy Core Facility, New York, NY 10021, USA
| | - Sara Cram
- Weill Cornell Medicine, Belfer Gene Therapy Core Facility, New York, NY 10021, USA
| | - Rajeshkumar Barur
- Cardiovascular Medicine, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA
| | - J. Kevin Donahue
- Cardiovascular Medicine, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA
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4
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Baggett BC, Murphy KR, Sengun E, Mi E, Cao Y, Turan NN, Lu Y, Schofield L, Kim TY, Kabakov AY, Bronk P, Qu Z, Camelliti P, Dubielecka P, Terentyev D, del Monte F, Choi BR, Sedivy J, Koren G. Myofibroblast senescence promotes arrhythmogenic remodeling in the aged infarcted rabbit heart. eLife 2023; 12:e84088. [PMID: 37204302 PMCID: PMC10259375 DOI: 10.7554/elife.84088] [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: 10/10/2022] [Accepted: 05/18/2023] [Indexed: 05/20/2023] Open
Abstract
Progressive tissue remodeling after myocardial infarction (MI) promotes cardiac arrhythmias. This process is well studied in young animals, but little is known about pro-arrhythmic changes in aged animals. Senescent cells accumulate with age and accelerate age-associated diseases. Senescent cells interfere with cardiac function and outcome post-MI with age, but studies have not been performed in larger animals, and the mechanisms are unknown. Specifically, age-associated changes in timecourse of senescence and related changes in inflammation and fibrosis are not well understood. Additionally, the cellular and systemic role of senescence and its inflammatory milieu in influencing arrhythmogenesis with age is not clear, particularly in large animal models with cardiac electrophysiology more similar to humans than previously studied animal models. Here, we investigated the role of senescence in regulating inflammation, fibrosis, and arrhythmogenesis in young and aged infarcted rabbits. Aged rabbits exhibited increased peri-procedural mortality and arrhythmogenic electrophysiological remodeling at the infarct border zone (IBZ) compared to young rabbits. Studies of the aged infarct zone revealed persistent myofibroblast senescence and increased inflammatory signaling over a 12-week timecourse. Senescent IBZ myofibroblasts in aged rabbits appear to be coupled to myocytes, and our computational modeling showed that senescent myofibroblast-cardiomyocyte coupling prolongs action potential duration (APD) and facilitates conduction block permissive of arrhythmias. Aged infarcted human ventricles show levels of senescence consistent with aged rabbits, and senescent myofibroblasts also couple to IBZ myocytes. Our findings suggest that therapeutic interventions targeting senescent cells may mitigate arrhythmias post-MI with age.
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Affiliation(s)
- Brett C Baggett
- Brown UniversityProvidenceUnited States
- Cardiovascular Research Center, Rhode Island HospitalProvidenceUnited States
| | - Kevin R Murphy
- Brown UniversityProvidenceUnited States
- Cardiovascular Research Center, Rhode Island HospitalProvidenceUnited States
| | - Elif Sengun
- Brown UniversityProvidenceUnited States
- Cardiovascular Research Center, Rhode Island HospitalProvidenceUnited States
- Department of Pharmacology, Institute of Graduate Studies in Health Sciences, Istanbul UniversityIstanbulTurkey
| | - Eric Mi
- Brown UniversityProvidenceUnited States
- Cardiovascular Research Center, Rhode Island HospitalProvidenceUnited States
| | - Yueming Cao
- Brown UniversityProvidenceUnited States
- Cardiovascular Research Center, Rhode Island HospitalProvidenceUnited States
| | - Nilufer N Turan
- Cardiovascular Research Center, Rhode Island HospitalProvidenceUnited States
| | - Yichun Lu
- Cardiovascular Research Center, Rhode Island HospitalProvidenceUnited States
| | - Lorraine Schofield
- Cardiovascular Research Center, Rhode Island HospitalProvidenceUnited States
| | - Tae Yun Kim
- Cardiovascular Research Center, Rhode Island HospitalProvidenceUnited States
| | - Anatoli Y Kabakov
- Brown UniversityProvidenceUnited States
- Cardiovascular Research Center, Rhode Island HospitalProvidenceUnited States
| | - Peter Bronk
- Cardiovascular Research Center, Rhode Island HospitalProvidenceUnited States
| | - Zhilin Qu
- School of Medicine, University of California, Los AngelesLos AngelesUnited States
| | - Patrizia Camelliti
- School of Biosciences and Medicine, University of SurreyGuildfordUnited Kingdom
| | - Patrycja Dubielecka
- Brown UniversityProvidenceUnited States
- Department of Hematology, Rhode Island HospitalProvidenceUnited States
| | - Dmitry Terentyev
- Cardiovascular Research Center, Rhode Island HospitalProvidenceUnited States
| | | | - Bum-Rak Choi
- Cardiovascular Research Center, Rhode Island HospitalProvidenceUnited States
| | | | - Gideon Koren
- Brown UniversityProvidenceUnited States
- Cardiovascular Research Center, Rhode Island HospitalProvidenceUnited States
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5
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Bains S, Zhou W, Dotzler SM, Martinez K, Kim CJ, Tester DJ, Ye D, Ackerman MJ. Suppression and Replacement Gene Therapy for KCNH2-Mediated Arrhythmias. CIRCULATION. GENOMIC AND PRECISION MEDICINE 2022; 15:e003719. [PMID: 36252106 DOI: 10.1161/circgen.122.003719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND KCNH2-mediated arrhythmia syndromes are caused by loss-of-function (type 2 long QT syndrome [LQT2]) or gain-of-function (type 1 short QT syndrome [SQT1]) pathogenic variants in the KCNH2-encoded Kv11.1 potassium channel, which is essential for the cardiac action potential. METHODS A dual-component "suppression-and-replacement" (SupRep) KCNH2 gene therapy was created by cloning into a single construct a custom-designed KCNH2 short hairpin RNA with ~80% knockdown (suppression) and a "short hairpin RNA-immune" KCNH2 cDNA (replacement). Induced pluripotent stem cell-derived cardiomyocytes and their CRISPR-Cas9 variant-corrected isogenic control (IC) induced pluripotent stem cell-derived cardiomyocytes were made for 2 LQT2- (G604S, N633S) and 1 SQT1- (N588K) causative variants. All variant lines were treated with KCNH2-SupRep or non-targeting control short hairpin RNA (shCT). The action potential duration (APD) at 90% repolarization (APD90) was measured using FluoVolt voltage dye. RESULTS KCNH2-SupRep achieved variant-independent rescue of both pathologic phenotypes. For LQT2-causative variants, treatment with KCNH2-SupRep resulted in shortening of the pathologically prolonged APD90 to near curative (IC-like) APD90 levels (G604S IC, 471±25 ms; N633S IC, 405±55 ms) compared with treatment with shCT (G604S: SupRep-treated, 452±76 ms versus shCT-treated, 550±41 ms; P<0.0001; N633S: SupRep-treated, 399±105 ms versus shCT-treated, 577±39 ms, P<0.0001). Conversely, for the SQT1-causative variant, N588K, treatment with KCNH2-SupRep resulted in therapeutic prolongation of the pathologically shortened APD90 (IC: 429±16 ms; SupRep-treated: 396±61 ms; shCT-treated: 274±12 ms). CONCLUSIONS We provide the first proof-of-principle gene therapy for correction of both LQT2 and SQT1. KCNH2-SupRep gene therapy successfully normalized the pathologic APD90, thereby eliminating the pathognomonic feature of both LQT2 and SQT1.
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Affiliation(s)
- Sahej Bains
- Medical Scientist Training Program (S.B., S.M.D.), Mayo Clinic, Rochester, MN.,Department of Molecular Pharmacology and Experimental Therapeutics (Windland Smith Rice Sudden Death Genomics Laboratory) (S.B., W.Z., S.M.D., K.M., C.S.J.K., D.J.T., D.Y., M.J.A.), Mayo Clinic, Rochester, MN
| | - Wei Zhou
- Department of Molecular Pharmacology and Experimental Therapeutics (Windland Smith Rice Sudden Death Genomics Laboratory) (S.B., W.Z., S.M.D., K.M., C.S.J.K., D.J.T., D.Y., M.J.A.), Mayo Clinic, Rochester, MN
| | - Steven M Dotzler
- Medical Scientist Training Program (S.B., S.M.D.), Mayo Clinic, Rochester, MN.,Department of Molecular Pharmacology and Experimental Therapeutics (Windland Smith Rice Sudden Death Genomics Laboratory) (S.B., W.Z., S.M.D., K.M., C.S.J.K., D.J.T., D.Y., M.J.A.), Mayo Clinic, Rochester, MN
| | - Katherine Martinez
- Department of Molecular Pharmacology and Experimental Therapeutics (Windland Smith Rice Sudden Death Genomics Laboratory) (S.B., W.Z., S.M.D., K.M., C.S.J.K., D.J.T., D.Y., M.J.A.), Mayo Clinic, Rochester, MN
| | - Cs John Kim
- Department of Molecular Pharmacology and Experimental Therapeutics (Windland Smith Rice Sudden Death Genomics Laboratory) (S.B., W.Z., S.M.D., K.M., C.S.J.K., D.J.T., D.Y., M.J.A.), Mayo Clinic, Rochester, MN
| | - David J Tester
- Department of Molecular Pharmacology and Experimental Therapeutics (Windland Smith Rice Sudden Death Genomics Laboratory) (S.B., W.Z., S.M.D., K.M., C.S.J.K., D.J.T., D.Y., M.J.A.), Mayo Clinic, Rochester, MN.,Department of Pediatric and Adolescent Medicine, Division of Pediatric Cardiology (D.J.T., M.J.A.), Mayo Clinic, Rochester, MN
| | - Dan Ye
- Department of Molecular Pharmacology and Experimental Therapeutics (Windland Smith Rice Sudden Death Genomics Laboratory) (S.B., W.Z., S.M.D., K.M., C.S.J.K., D.J.T., D.Y., M.J.A.), Mayo Clinic, Rochester, MN.,Division of Heart Rhythm Services, Department of Cardiovascular Medicine, Windland Smith Rice Genetic Heart Rhythm Clinic (D.J.T., M.J.A.), Mayo Clinic, Rochester, MN
| | - Michael J Ackerman
- Department of Molecular Pharmacology and Experimental Therapeutics (Windland Smith Rice Sudden Death Genomics Laboratory) (S.B., W.Z., S.M.D., K.M., C.S.J.K., D.J.T., D.Y., M.J.A.), Mayo Clinic, Rochester, MN.,Department of Pediatric and Adolescent Medicine, Division of Pediatric Cardiology (D.J.T., M.J.A.), Mayo Clinic, Rochester, MN.,Division of Heart Rhythm Services, Department of Cardiovascular Medicine, Windland Smith Rice Genetic Heart Rhythm Clinic (D.J.T., M.J.A.), Mayo Clinic, Rochester, MN
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6
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Kreifels P, Bodi I, Hornyik T, Franke G, Perez-Feliz S, Lewetag R, Moss R, Castiglione A, Ziupa D, Zehender M, Brunner M, Bode C, Odening KE. Oxytocin exerts harmful cardiac repolarization prolonging effects in drug-induced LQTS. IJC HEART & VASCULATURE 2022; 40:101001. [PMID: 35391783 PMCID: PMC8980310 DOI: 10.1016/j.ijcha.2022.101001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 03/07/2022] [Accepted: 03/08/2022] [Indexed: 11/25/2022]
Abstract
Background Oxytocin is used therapeutically in psychiatric patients. Many of these also receive anti-depressant or anti-psychotic drugs causing acquired long-QT-syndrome (LQTS) by blocking HERG/IKr. We previously identified an oxytocin-induced QT-prolongation in LQT2 rabbits, indicating potential harmful effects of combined therapy. We thus aimed to analyze the effects of dual therapy with oxytocin and fluoxetine/risperidone on cardiac repolarization. Methods Effects of risperidone, fluoxetine and oxytocin on QT/QTc, short-term variability (STV) of QT, and APD were assessed in rabbits using in vivo ECG and ex vivo monophasic AP recordings in Langendorff-perfused hearts. Underlying mechanisms were assessed using patch clamp in isolated cardiomyocytes. Results Oxytocin, fluoxetine and risperidone prolonged QTc and APD in whole hearts. The combination of fluoxetine + oxytocin resulted in further QTc- and APD-prolongation, risperidone + oxytocin tended to increase QTc and APD compared to monotherapy. Temporal QT instability, STVQTc was increased by oxytocin, fluoxetine / fluoxetine + oxytocin and risperidone / risperidone + oxytocin. Similar APD-prolonging effects were confirmed in isolated cardiomyocytes due to differential effects of the compounds on repolarizing ion currents: Oxytocin reduced IKs, fluoxetine and risperidone reduced IKr, resulting in additive effects on IKtotal-tail. In addition, oxytocin reduced IK1, further reducing the repolarization reserve. Conclusion Oxytocin, risperidone and fluoxetine prolong QTc / APD. Combined treatment further prolongs QTc/APD due to differential effects on IKs and IK1 (block by oxytocin) and IKr (block by risperidone and fluoxetine), leading to pronounced impairment of repolarization reserve. Oxytocin should be used with caution in patients in the context of acquired LQTS.
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7
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Sanchez-Conde FG, Jimenez-Vazquez EN, Auerbach DS, Jones DK. The ERG1 K+ Channel and Its Role in Neuronal Health and Disease. Front Mol Neurosci 2022; 15:890368. [PMID: 35600076 PMCID: PMC9113952 DOI: 10.3389/fnmol.2022.890368] [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: 03/05/2022] [Accepted: 04/11/2022] [Indexed: 11/30/2022] Open
Abstract
The ERG1 potassium channel, encoded by KCNH2, has long been associated with cardiac electrical excitability. Yet, a growing body of work suggests that ERG1 mediates physiology throughout the human body, including the brain. ERG1 is a regulator of neuronal excitability, ERG1 variants are associated with neuronal diseases (e.g., epilepsy and schizophrenia), and ERG1 serves as a potential therapeutic target for neuronal pathophysiology. This review summarizes the current state-of-the-field regarding the ERG1 channel structure and function, ERG1’s relationship to the mammalian brain and highlights key questions that have yet to be answered.
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Affiliation(s)
| | - Eric N. Jimenez-Vazquez
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI, United States
| | - David S. Auerbach
- Department of Pharmacology, State University of New York Upstate Medical University, Syracuse, NY, United States
- *Correspondence: David S. Auerbach,
| | - David K. Jones
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI, United States
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI, United States
- David K. Jones,
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8
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Edwards AG, Mørk H, Stokke MK, Lipsett DB, Sjaastad I, Richard S, Sejersted OM, Louch WE. Sarcoplasmic Reticulum Calcium Release Is Required for Arrhythmogenesis in the Mouse. Front Physiol 2021; 12:744730. [PMID: 34712150 PMCID: PMC8546347 DOI: 10.3389/fphys.2021.744730] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 09/20/2021] [Indexed: 11/23/2022] Open
Abstract
Dysfunctional sarcoplasmic reticulum Ca2+ handling is commonly observed in heart failure, and thought to contribute to arrhythmogenesis through several mechanisms. Some time ago we developed a cardiomyocyte-specific inducible SERCA2 knockout mouse, which is remarkable in the degree to which major adaptations to sarcolemmal Ca2+ entry and efflux overcome the deficit in SR reuptake to permit relatively normal contractile function. Conventionally, those adaptations would also be expected to dramatically increase arrhythmia susceptibility. However, that susceptibility has never been tested, and it is possible that the very rapid repolarization of the murine action potential (AP) allows for large changes in sarcolemmal Ca2+ transport without substantially disrupting electrophysiologic stability. We investigated this hypothesis through telemetric ECG recording in the SERCA2-KO mouse, and patch-clamp electrophysiology, Ca2+ imaging, and mathematical modeling of isolated SERCA2-KO myocytes. While the SERCA2-KO animals exhibit major (and unique) electrophysiologic adaptations at both the organ and cell levels, they remain resistant to arrhythmia. A marked increase in peak L-type calcium (ICaL) current and slowed ICaL decay elicited pronounced prolongation of initial repolarization, but faster late repolarization normalizes overall AP duration. Early afterdepolarizations were seldom observed in KO animals, and those that were observed exhibited a mechanism intermediate between murine and large mammal dynamical properties. As expected, spontaneous SR Ca2+ sparks and waves were virtually absent. Together these findings suggest that intact SR Ca2+ handling is an absolute requirement for triggered arrhythmia in the mouse, and that in its absence, dramatic changes to the major inward currents can be resisted by the substantial K+ current reserve, even at end-stage disease.
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Affiliation(s)
- Andrew G Edwards
- Institute for Experimental Medical Research, Oslo University Hospital, University of Oslo, Oslo, Norway.,Department of Pharmacology, University of California, Davis, Davis, CA, United States
| | - Halvor Mørk
- Institute for Experimental Medical Research, Oslo University Hospital, University of Oslo, Oslo, Norway
| | - Mathis K Stokke
- Institute for Experimental Medical Research, Oslo University Hospital, University of Oslo, Oslo, Norway.,K.G. Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway.,Department of Cardiology, Oslo University Hospital, Oslo, Norway
| | - David B Lipsett
- Institute for Experimental Medical Research, Oslo University Hospital, University of Oslo, Oslo, Norway
| | - Ivar Sjaastad
- Institute for Experimental Medical Research, Oslo University Hospital, University of Oslo, Oslo, Norway.,K.G. Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
| | - Sylvain Richard
- Université de Montpellier, INSERM, CNRS, PhyMedExp, Montpellier, France
| | - Ole M Sejersted
- Institute for Experimental Medical Research, Oslo University Hospital, University of Oslo, Oslo, Norway
| | - William E Louch
- Institute for Experimental Medical Research, Oslo University Hospital, University of Oslo, Oslo, Norway.,K.G. Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
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9
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Liu M, Liu H, Parthiban P, Kang GJ, Shi G, Feng F, Zhou A, Gu L, Karnopp C, Tolkacheva EG, Dudley SC. Inhibition of the unfolded protein response reduces arrhythmic risk after myocardial infarction. J Clin Invest 2021; 131:e147836. [PMID: 34324437 DOI: 10.1172/jci147836] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Accepted: 07/28/2021] [Indexed: 11/17/2022] Open
Abstract
Ischemic cardiomyopathy is associated with an increased risk of sudden death, activation of the unfolded protein response (UPR), and reductions in multiple cardiac ion channels. When activated, the protein kinase-like ER kinase (PERK) branch of the UPR reduces protein translation and abundance. We hypothesized that PERK inhibition could prevent ion channel downregulation and reduce arrhythmic risk after myocardial infarct (MI). MI induced by coronary artery ligation resulted in mice exhibited reduced ion channel levels, ventricular tachycardia (VT), and prolonged corrected intervals between the Q and T waves of the ECGs (QTc). Protein levels of major cardiac ion channels were decreased. MI cardiomyocytes showed significantly prolonged action potential duration and decreased maximum upstroke velocity. Cardiac-specific PERK knockout (PERKKO) reduced electrical remodeling in response to MI with shortened QTc intervals, less VT episodes, and higher survival rates (P<0.05 vs. MI). Pharmacological PERK inhibition had similar effects. In conclusion, activated PERK during MI contributed to arrhythmic risk by downregulation of select cardiac ion channels. PERK inhibition prevented these changes and reduced arrhythmic risk. These results suggest that ion channel downregulation during MI is a fundamental arrhythmic mechanism and maintaining ion channel levels is antiarrhythmic.
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Affiliation(s)
- Man Liu
- Lillehei Heart Institute, University of Minnesota, Minneapolis, United States of America
| | - Hong Liu
- Lillehei Heart Institute, University of Minnesota, Minneapolis, United States of America
| | - Preethy Parthiban
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, United States of America
| | - Gyeoung-Jin Kang
- Lillehei Heart Institute, University of Minnesota, Minneapolis, United States of America
| | - Guangbin Shi
- Department of Medicine, Brown University, Providence, United States of America
| | - Feng Feng
- Lillehei Heart Institute, University of Minnesota, Minneapolis, United States of America
| | - Anyu Zhou
- Department of Medicine, Brown University, Providence, United States of America
| | - Lianzhi Gu
- Lillehei Heart Institute, University of Minnesota, Minneapolis, United States of America
| | - Courtney Karnopp
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, United States of America
| | - Elena G Tolkacheva
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, United States of America
| | - Samuel C Dudley
- Lillehei Heart Institute, University of Minnesota, Minneapolis, United States of America
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10
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Arrhythmic risk during pregnancy and postpartum in patients with long QT syndrome. Herzschrittmacherther Elektrophysiol 2021; 32:180-185. [PMID: 33782754 PMCID: PMC8166676 DOI: 10.1007/s00399-021-00757-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 03/16/2021] [Indexed: 12/13/2022]
Abstract
Congenital long QT syndrome (LQTS) is a genetic disorder characterized by a prolonged QT interval in the surface electrocardiogram (ECG) that predisposes affected individuals to arrhythmic syncope, ventricular torsades-de-pointes, and sudden cardiac death at a young age. Investigations of large patient cohorts revealed sex-related differences in the LQTS phenotype. Adult women with LQTS are at higher risk for cardiac arrhythmias than are adult men with LQTS. Sex hormones are thought to play the primary role for these gender differences. Clinical experience and translational studies indicated that females with LQTS have a lower risk for cardiac arrhythmias during pregnancy and elevated risk in the postpartum period due to contrasting effects of estradiol and progesterone, as well as postpartum hormones on the action potential and arrhythmia substrate. However, this pro- or anti-arrhythmic potential of hormones varies depending on the underlying genotype, partly since sex hormones have distinct effects on different (affected) cardiac ion channels. Thus, a comprehensive evaluation of women with LQTS prior to and during pregnancy, during labor, and in the postpartum period with consideration of the patient’s disease- and gene-specific risk factors is essential to providing precision management in this patient group. This review discusses the current understanding of hormonal influences in LQTS and provides practical guidance for the optimal management of LQTS patients during pregnancy, delivery, and the postpartum period.
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11
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Fan J, Wang Y, Chen YE. Genetically Modified Rabbits for Cardiovascular Research. Front Genet 2021; 12:614379. [PMID: 33603774 PMCID: PMC7885269 DOI: 10.3389/fgene.2021.614379] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 01/04/2021] [Indexed: 12/21/2022] Open
Abstract
Rabbits are one of the most used experimental animals for investigating the mechanisms of human cardiovascular disease and lipid metabolism because they are phylogenetically closer to human than rodents (mice and rats). Cholesterol-fed wild-type rabbits were first used to study human atherosclerosis more than 100 years ago and are still playing an important role in cardiovascular research. Furthermore, transgenic rabbits generated by pronuclear microinjection provided another means to investigate many gene functions associated with human disease. Because of the lack of both rabbit embryonic stem cells and the genome information, for a long time, it has been a dream for scientists to obtain knockout rabbits generated by homologous recombination-based genomic manipulation as in mice. This obstacle has greatly hampered using genetically modified rabbits to disclose the molecular mechanisms of many human diseases. The advent of genome editing technologies has dramatically extended the applications of experimental animals including rabbits. In this review, we will update genetically modified rabbits, including transgenic, knock-out, and knock-in rabbits during the past decades regarding their use in cardiovascular research and point out the perspectives in future.
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Affiliation(s)
- Jianglin Fan
- Department of Pathology, Xi'an Medical University, Xi'an, China.,Department of Molecular Pathology, Faculty of Medicine, Graduate School of Interdisciplinary Research, University of Yamanashi, Yamanashi, Japan.,School of Biotechnology and Health Sciences, Wuyi University, Jiangmen, China
| | - Yanli Wang
- Department of Pathology, Xi'an Medical University, Xi'an, China
| | - Y Eugene Chen
- Center for Advanced Models for Translational Sciences and Therapeutics, University of Michigan Medical Center, Ann Arbor, MI, United States
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12
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Hamilton S, Veress R, Belevych A, Terentyev D. The role of calcium homeostasis remodeling in inherited cardiac arrhythmia syndromes. Pflugers Arch 2021; 473:377-387. [PMID: 33404893 PMCID: PMC7940310 DOI: 10.1007/s00424-020-02505-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 12/08/2020] [Accepted: 12/10/2020] [Indexed: 02/07/2023]
Abstract
Sudden cardiac death due to malignant ventricular arrhythmias remains the major cause of mortality in the postindustrial world. Defective intracellular Ca2+ homeostasis has been well established as a key contributing factor to the enhanced propensity for arrhythmia in acquired cardiac disease, such as heart failure or diabetic cardiomyopathy. More recent advances provide a strong basis to the emerging view that hereditary cardiac arrhythmia syndromes are accompanied by maladaptive remodeling of Ca2+ homeostasis which substantially increases arrhythmic risk. This brief review will focus on functional changes in elements of Ca2+ handling machinery in cardiomyocytes that occur secondary to genetic mutations associated with catecholaminergic polymorphic ventricular tachycardia, and long QT syndrome.
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Affiliation(s)
- Shanna Hamilton
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, Wexner Medical Center, The Ohio State University, Columbus, OH, USA
| | - Roland Veress
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, Wexner Medical Center, The Ohio State University, Columbus, OH, USA
| | - Andriy Belevych
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, Wexner Medical Center, The Ohio State University, Columbus, OH, USA
| | - Dmitry Terentyev
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, Wexner Medical Center, The Ohio State University, Columbus, OH, USA.
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13
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Varró A, Tomek J, Nagy N, Virág L, Passini E, Rodriguez B, Baczkó I. Cardiac transmembrane ion channels and action potentials: cellular physiology and arrhythmogenic behavior. Physiol Rev 2020; 101:1083-1176. [PMID: 33118864 DOI: 10.1152/physrev.00024.2019] [Citation(s) in RCA: 72] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Cardiac arrhythmias are among the leading causes of mortality. They often arise from alterations in the electrophysiological properties of cardiac cells and their underlying ionic mechanisms. It is therefore critical to further unravel the pathophysiology of the ionic basis of human cardiac electrophysiology in health and disease. In the first part of this review, current knowledge on the differences in ion channel expression and properties of the ionic processes that determine the morphology and properties of cardiac action potentials and calcium dynamics from cardiomyocytes in different regions of the heart are described. Then the cellular mechanisms promoting arrhythmias in congenital or acquired conditions of ion channel function (electrical remodeling) are discussed. The focus is on human-relevant findings obtained with clinical, experimental, and computational studies, given that interspecies differences make the extrapolation from animal experiments to human clinical settings difficult. Deepening the understanding of the diverse pathophysiology of human cellular electrophysiology will help in developing novel and effective antiarrhythmic strategies for specific subpopulations and disease conditions.
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Affiliation(s)
- András Varró
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary.,MTA-SZTE Cardiovascular Pharmacology Research Group, Hungarian Academy of Sciences, Szeged, Hungary
| | - Jakub Tomek
- Department of Computer Science, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Norbert Nagy
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary.,MTA-SZTE Cardiovascular Pharmacology Research Group, Hungarian Academy of Sciences, Szeged, Hungary
| | - László Virág
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Elisa Passini
- Department of Computer Science, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Blanca Rodriguez
- Department of Computer Science, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - István Baczkó
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
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14
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Abstract
Transgenic rabbits have contributed to the progress of biomedical science as human disease models because of their unique features, such as the lipid metabolism system similar to humans and medium body size that facilitates handling and experimental manipulation. In fact, many useful transgenic rabbits have been generated and used in research fields such as lipid metabolism and atherosclerosis, cardiac failure, immunology, and oncogenesis. However, there have been long-term problems, namely that the transgenic efficiency when using pronuclear microinjection is low compared with transgenic mice and production of knockout rabbits is impossible owing to the lack of embryonic stem cells for gene targeting in rabbits. Despite these limitations, the emergence of novel genome editing technology has changed the production of genetically modified animals including the rabbit. We are finally able to produce both transgenic and knockout rabbit models to analyze gain- and loss-of-functions of specific genes. It is expected that the use of genetically modified rabbits will extend to various research fields. In this review, we describe the unique features of rabbits as laboratory animals, the current status of their development and use, and future perspectives of transgenic rabbit models for human diseases.
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15
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Hornyik T, Castiglione A, Franke G, Perez-Feliz S, Major P, Hiripi L, Koren G, Bősze Z, Varró A, Zehender M, Brunner M, Bode C, Baczkó I, Odening KE. Transgenic LQT2, LQT5, and LQT2-5 rabbit models with decreased repolarisation reserve for prediction of drug-induced ventricular arrhythmias. Br J Pharmacol 2020; 177:3744-3759. [PMID: 32436214 PMCID: PMC7393202 DOI: 10.1111/bph.15098] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 04/09/2020] [Accepted: 04/23/2020] [Indexed: 12/21/2022] Open
Abstract
Background and Purpose Reliable prediction of pro‐arrhythmic side effects of novel drug candidates is still a major challenge. Although drug‐induced pro‐arrhythmia occurs primarily in patients with pre‐existing repolarisation disturbances, healthy animals are employed for pro‐arrhythmia testing. To improve current safety screening, transgenic long QT (LQTS) rabbit models with impaired repolarisation reserve were generated by overexpressing loss‐of‐function mutations of human HERG (HERG‐G628S, loss of IKr; LQT2), KCNE1 (KCNE1‐G52R, decreased IKs; LQT5), or both transgenes (LQT2‐5) in the heart. Experimental Approach Effects of K+ channel blockers on cardiac repolarisation and arrhythmia susceptibility were assessed in healthy wild‐type (WT) and LQTS rabbits using in vivo ECG and ex vivo monophasic action potential and ECG recordings in Langendorff‐perfused hearts. Key Results LQTS models reflect patients with clinically “silent” (LQT5) or “manifest” (LQT2 and LQT2‐5) impairment in cardiac repolarisation reserve: they were more sensitive in detecting IKr‐blocking (LQT5) or IK1/IKs‐blocking (LQT2 and LQT2‐5) properties of drugs compared to healthy WT animals. Impaired QT‐shortening capacity at fast heart rates was observed due to disturbed IKs function in LQT5 and LQT2‐5. Importantly, LQTS models exhibited higher incidence, longer duration, and more malignant types of ex vivo arrhythmias than WT. Conclusion and Implications LQTS models represent patients with reduced repolarisation reserve due to different pathomechanisms. As they demonstrate increased sensitivity to different specific ion channel blockers (IKr blockade in LQT5 and IK1 and IKs blockade in LQT2 and LQT2‐5), their combined use could provide more reliable and more thorough prediction of (multichannel‐based) pro‐arrhythmic potential of novel drug candidates.
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Affiliation(s)
- Tibor Hornyik
- Department of Cardiology and Angiology I, Heart Center University of Freiburg, Medical Faculty, Freiburg, Germany.,Institute of Experimental Cardiovascular Medicine, Heart Center University of Freiburg, Medical Faculty, Freiburg, Germany.,Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - Alessandro Castiglione
- Department of Cardiology and Angiology I, Heart Center University of Freiburg, Medical Faculty, Freiburg, Germany
| | - Gerlind Franke
- Department of Cardiology and Angiology I, Heart Center University of Freiburg, Medical Faculty, Freiburg, Germany
| | - Stefanie Perez-Feliz
- Department of Cardiology and Angiology I, Heart Center University of Freiburg, Medical Faculty, Freiburg, Germany.,Institute of Experimental Cardiovascular Medicine, Heart Center University of Freiburg, Medical Faculty, Freiburg, Germany
| | - Péter Major
- NARIC-Agricultural Biotechnology Institute, Animal Biotechnology Department, Gödöllő, Hungary
| | - László Hiripi
- NARIC-Agricultural Biotechnology Institute, Animal Biotechnology Department, Gödöllő, Hungary
| | - Gideon Koren
- Cardiovascular Research Center, Brown University, Providence, Rhode Island, USA
| | - Zsuzsanna Bősze
- NARIC-Agricultural Biotechnology Institute, Animal Biotechnology Department, Gödöllő, Hungary
| | - András Varró
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - Manfred Zehender
- Department of Cardiology and Angiology I, Heart Center University of Freiburg, Medical Faculty, Freiburg, Germany
| | - Michael Brunner
- Department of Cardiology and Angiology I, Heart Center University of Freiburg, Medical Faculty, Freiburg, Germany.,Department of Cardiology and Medical Intensive Care, St. Josefskrankenhaus, Freiburg, Germany
| | - Christoph Bode
- Department of Cardiology and Angiology I, Heart Center University of Freiburg, Medical Faculty, Freiburg, Germany
| | - István Baczkó
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - Katja E Odening
- Department of Cardiology and Angiology I, Heart Center University of Freiburg, Medical Faculty, Freiburg, Germany.,Institute of Experimental Cardiovascular Medicine, Heart Center University of Freiburg, Medical Faculty, Freiburg, Germany.,Translational Cardiology, Department of Cardiology, Inselspital, Bern University Hospital, and Institute of Physiology, University of Bern, Bern, Switzerland
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16
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Baczkó I, Hornyik T, Brunner M, Koren G, Odening KE. Transgenic Rabbit Models in Proarrhythmia Research. Front Pharmacol 2020; 11:853. [PMID: 32581808 PMCID: PMC7291951 DOI: 10.3389/fphar.2020.00853] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Accepted: 05/22/2020] [Indexed: 12/23/2022] Open
Abstract
Drug-induced proarrhythmia constitutes a potentially lethal side effect of various drugs. Most often, this proarrhythmia is mechanistically linked to the drug's potential to interact with repolarizing cardiac ion channels causing a prolongation of the QT interval in the ECG. Despite sophisticated screening approaches during drug development, reliable prediction of proarrhythmia remains very challenging. Although drug-induced long-QT-related proarrhythmia is often favored by conditions or diseases that impair the individual's repolarization reserve, most cellular, tissue, and whole animal model systems used for drug safety screening are based on normal, healthy models. In recent years, several transgenic rabbit models for different types of long QT syndromes (LQTS) with differences in the extent of impairment in repolarization reserve have been generated. These might be useful for screening/prediction of a drug's potential for long-QT-related proarrhythmia, particularly as different repolarizing cardiac ion channels are impaired in the different models. In this review, we summarize the electrophysiological characteristics of the available transgenic LQTS rabbit models, and the pharmacological proof-of-principle studies that have been performed with these models—highlighting the advantages and disadvantages of LQTS models for proarrhythmia research. In the end, we give an outlook on potential future directions and novel models.
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Affiliation(s)
- István Baczkó
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - Tibor Hornyik
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary.,Department of Cardiology and Angiology I, Heart Center, University of Freiburg, Freiburg, Germany.,Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Michael Brunner
- Department of Cardiology and Angiology I, Heart Center, University of Freiburg, Freiburg, Germany.,Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Department of Cardiology and Medical Intensive Care, St. Josefskrankenhaus, Freiburg, Germany
| | - Gideon Koren
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, RI, United States
| | - Katja E Odening
- Department of Cardiology and Angiology I, Heart Center, University of Freiburg, Freiburg, Germany.,Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Translational Cardiology, Department of Cardiology, Inselspital, Bern University Hospital, Bern, Switzerland.,Institute of Physiology, University of Bern, Bern, Switzerland
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17
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Kim TY, Jeng P, Hwang J, Pfeiffer Z, Patel D, Cooper LL, Kossidas K, Centracchio J, Peng X, Koren G, Qu Z, Choi BR. Short-Long Heart Rate Variation Increases Dispersion of Action Potential Duration in Long QT Type 2 Transgenic Rabbit Model. Sci Rep 2019; 9:14849. [PMID: 31619700 PMCID: PMC6795902 DOI: 10.1038/s41598-019-51230-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 09/24/2019] [Indexed: 01/21/2023] Open
Abstract
The initiation of polymorphic ventricular tachycardia in long QT syndrome type 2 (LQT2) has been associated with a characteristic ECG pattern of short-long RR intervals. We hypothesize that this characteristic pattern increases APD dispersion in LQT2, thereby promoting arrhythmia. We investigated APD dispersion and its dependence on two previous cycle lengths (CLs) in transgenic rabbit models of LQT2, LQT1, and their littermate controls (LMC) using random stimulation protocols. The results show that the short-long RR pattern was associated with a larger APD dispersion in LQT2 but not in LQT1 rabbits. The multivariate analyses of APD as a function of two previous CLs (APDn = C + α1CLn−1 + α2CLn−2) showed that α1 (APD restitution slope) is largest and heterogeneous in LQT2 but uniform in LQT1, enhancing APD dispersion under long CLn−1 in LQT2. The α2 (short-term memory) was negative in LQT2 while positive in LQT1, and the spatial pattern of α1 was inversely correlated to α2 in LQT2, which explains why a short-long combination causes a larger APD dispersion in LQT2 but not in LQT1 rabbits. In conclusion, short-long RR pattern increased APD dispersion only in LQT2 rabbits through heterogeneous APD restitution and the short-term memory, underscoring the genotype-specific triggering of arrhythmias in LQT syndrome.
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Affiliation(s)
- Tae Yun Kim
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, RI, USA
| | - Paul Jeng
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, RI, USA
| | - JungMin Hwang
- College of Pharmacy, University of Rhode Island, Kingston, RI, USA
| | - Zachary Pfeiffer
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, RI, USA
| | - Divyang Patel
- Department of Cardiovascular Medicine, Heart and Vascular Institute, Cleveland Clinic Foundation, Cleveland, Ohio, USA
| | - Leroy L Cooper
- Biology Department, Vassar College, Poughkeepsie, NY, USA
| | - Konstantinos Kossidas
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, RI, USA
| | - Jason Centracchio
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, RI, USA
| | - Xuwen Peng
- Department of Comparative Medicine, Pennsylvania State University College of Medicine, Hershey, PA, USA
| | - Gideon Koren
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, RI, USA
| | - Zhilin Qu
- Department of Medicine (Cardiology), David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Bum-Rak Choi
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, RI, USA.
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18
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Zhou X, Bueno-Orovio A, Schilling RJ, Kirkby C, Denning C, Rajamohan D, Burrage K, Tinker A, Rodriguez B, Harmer SC. Investigating the Complex Arrhythmic Phenotype Caused by the Gain-of-Function Mutation KCNQ1-G229D. Front Physiol 2019; 10:259. [PMID: 30967788 PMCID: PMC6430739 DOI: 10.3389/fphys.2019.00259] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 02/28/2019] [Indexed: 12/18/2022] Open
Abstract
The congenital long QT syndrome (LQTS) is a cardiac electrophysiological disorder that can cause sudden cardiac death. LQT1 is a subtype of LQTS caused by mutations in KCNQ1, affecting the slow delayed-rectifier potassium current (I Ks), which is essential for cardiac repolarization. Paradoxically, gain-of-function mutations in KCNQ1 have been reported to cause borderline QT prolongation, atrial fibrillation (AF), sinus bradycardia, and sudden death, however, the mechanisms are not well understood. The goal of the study is to investigate the ionic, cellular and tissue mechanisms underlying the complex phenotype of a gain-of-function mutation in KCNQ1, c.686G > A (p.G229D) using computer modeling and simulations informed by in vitro measurements. Previous studies have shown this mutation to cause AF and borderline QT prolongation. We report a clinical description of a family that carry this mutation and that a member of the family died suddenly during sleep at 21 years old. Using patch-clamp experiments, we confirm that KCNQ1-G229D causes a significant gain in channel function. We introduce the effect of the mutation in populations of atrial, ventricular and sinus node (SN) cell models to investigate mechanisms underlying phenotypic variability. In a population of human atrial and ventricular cell models and tissue, the presence of KCNQ1-G229D predominantly shortens atrial action potential duration (APD). However, in a subset of models, KCNQ1-G229D can act to prolong ventricular APD by up to 7% (19 ms) and underlie depolarization abnormalities, which could promote QT prolongation and conduction delays. Interestingly, APD prolongations were predominantly seen at slow pacing cycle lengths (CL > 1,000 ms), which suggests a greater arrhythmic risk during bradycardia, and is consistent with the observed sudden death during sleep. In a population of human SN cell models, the KCNQ1-G229D mutation results in slow/abnormal sinus rhythm, and we identify that a stronger L-type calcium current enables the SN to be more robust to the mutation. In conclusion, our computational modeling experiments provide novel mechanistic explanations for the observed borderline QT prolongation, and predict that KCNQ1-G229D could underlie SN dysfunction and conduction delays. The mechanisms revealed in the study can potentially inform management and treatment of KCNQ1 gain-of-function mutation carriers.
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Affiliation(s)
- Xin Zhou
- Department of Computer Science, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Alfonso Bueno-Orovio
- Department of Computer Science, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | | | | | - Chris Denning
- Department of Stem Cell Biology, Centre for Biomolecular Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Divya Rajamohan
- Department of Stem Cell Biology, Centre for Biomolecular Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Kevin Burrage
- Department of Computer Science, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
- Australian Research Council Centre of Excellence for Mathematical and Statistical Frontiers, Queensland University of Technology, Brisbane, QLD, Australia
- School of Mathematical Sciences, Queensland University of Technology, Brisbane, QLD, Australia
| | - Andrew Tinker
- The William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
| | - Blanca Rodriguez
- Department of Computer Science, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Stephen C. Harmer
- The William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
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19
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Charisopoulou D, Koulaouzidis G, Rydberg A, Michael HY. Exercise worsening of electromechanical disturbances: A predictor of arrhythmia in long QT syndrome. Clin Cardiol 2018; 42:235-240. [PMID: 30537240 PMCID: PMC6712344 DOI: 10.1002/clc.23132] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2018] [Revised: 10/29/2018] [Accepted: 12/06/2018] [Indexed: 01/06/2023] Open
Abstract
Background Electromechanical (EM) coupling heterogeneity is significant in long QT syndrome (LQTS), particularly in symptomatic patients; EM window (EMW) has been proposed as an indicator of interaction and a better predictor of arrhythmia than QTc. Hypothesis To investigate the dynamic response of EMW to exercise in LQTS and its predictive value of arrhythmia. Methods Forty‐seven LQTS carriers (45 ± 15 years, 20 with arrhythmic events), and 35 controls underwent exercise echocardiogram. EMW was measured as the time difference between aortic valve closure on Doppler and the end of QT interval on the superimposed electrocardiogram (ECG). Measurements were obtained at rest, peak exercise (PE) and 4 minutes into recovery. Results Patients did not differ in age, gender, heart rate, or left ventricular ejection fraction but had a negative resting EMW compared with controls (−42 ± 22 vs 17 ± 5 ms, P < 0.0001). EMW became more negative at PE (−89 ± 43 vs 16 ± 7 ms, P = 0.0001) and recovery (−65 ± 39 vs 16 ± 6 ms, P = 0.001) in patients, particularly the symptomatic, but remained unchanged in controls. PE EMW was a stronger predictor of arrhythmic events than QTc (AUC:0.765 vs 0.569, P < 0.001). B‐blockers did not affect EMW at rest but was less negative at PE (BB: −66 ± 21 vs no‐BB: −113 ± 25 ms, P < 0.001). LQT1 patients had worse PE EMW negativity than LQT2. Conclusion LQTS patients have significantly negative EMW, which worsens with exercise. These changes are more pronounced in patients with documented arrhythmic events and decrease with B‐blocker therapy. Thus, EMW assessment during exercise may help improve risk stratification and management of LQTS patients.
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Affiliation(s)
- Dafni Charisopoulou
- Institute of Public Health and Clinical Medicine, Umea University, Umea, Sweden.,Department of Paediatric Cardiology, Leeds Teaching Hospitals NHS Trust, Leeds, UK
| | - George Koulaouzidis
- Institute of Public Health and Clinical Medicine, Umea University, Umea, Sweden.,Department of Cardiology, Mid Yorkshire Hospitals NHS Trust, Wakefield, UK
| | - Annika Rydberg
- Department of Clinical Sciences, Paediatrics, Umea University, Umea, Sweden
| | - Henein Y Michael
- Institute of Public Health and Clinical Medicine, Umea University, Umea, Sweden.,Molecular and Clinical Sciences Research Institute, St George University London, London, UK.,Brunel University, Middlesex, UK
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20
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Roder K, Kabakov A, Moshal KS, Murphy KR, Xie A, Dudley S, Turan NN, Lu Y, MacRae CA, Koren G. Trafficking of the human ether-a-go-go-related gene (hERG) potassium channel is regulated by the ubiquitin ligase rififylin (RFFL). J Biol Chem 2018; 294:351-360. [PMID: 30401747 DOI: 10.1074/jbc.ra118.003852] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Revised: 10/17/2018] [Indexed: 11/06/2022] Open
Abstract
The QT interval is an important diagnostic feature on surface electrocardiograms because it reflects the duration of the ventricular action potential. A previous genome-wide association study has reported a significant linkage between a single-nucleotide polymorphism ∼11.7 kb downstream of the gene encoding the RING finger ubiquitin ligase rififylin (RFFL) and variability in the QT interval. This, along with results in animal studies, suggests that RFFL may have effects on cardiac repolarization. Here, we sought to determine the role of RFFL in cardiac electrophysiology. Adult rabbit cardiomyocytes with adenovirus-expressed RFFL exhibited reduced rapid delayed rectifier current (I Kr). Neonatal rabbit cardiomyocytes transduced with RFFL-expressing adenovirus exhibited reduced total expression of the potassium channel ether-a-go-go-related gene (rbERG). Using transfections of 293A cells and Western blotting experiments, we observed that RFFL and the core-glycosylated form of the human ether-a-go-go-related gene (hERG) potassium channel interact. Furthermore, RFFL overexpression led to increased polyubiquitination and proteasomal degradation of hERG protein and to an almost complete disappearance of I Kr, which depended on the intact RING domain of RFFL. Blocking the ER-associated degradation (ERAD) pathway with a dominant-negative form of the ERAD core component, valosin-containing protein (VCP), in 293A cells partially abolished RFFL-mediated hERG degradation. We further substantiated the link between RFFL and ERAD by showing an interaction between RFFL and VCP in vitro We conclude that RFFL is an important regulator of voltage-gated hERG potassium channel activity and therefore cardiac repolarization and that this ubiquitination-mediated regulation requires parts of the ERAD pathway.
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Affiliation(s)
- Karim Roder
- Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, Rhode Island 02903
| | - Anatoli Kabakov
- Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, Rhode Island 02903
| | - Karni S Moshal
- Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, Rhode Island 02903
| | - Kevin R Murphy
- Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, Rhode Island 02903
| | - An Xie
- Department of Medicine, University of Minnesota, Cardiovascular Division, Minneapolis, Minnesota 55455
| | - Samuel Dudley
- Department of Medicine, University of Minnesota, Cardiovascular Division, Minneapolis, Minnesota 55455
| | - Nilüfer N Turan
- Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, Rhode Island 02903
| | - Yichun Lu
- Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, Rhode Island 02903
| | - Calum A MacRae
- Cardiovascular Division, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115
| | - Gideon Koren
- Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, Rhode Island 02903.
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21
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Thomas D, Christ T, Fabritz L, Goette A, Hammwöhner M, Heijman J, Kockskämper J, Linz D, Odening KE, Schweizer PA, Wakili R, Voigt N. German Cardiac Society Working Group on Cellular Electrophysiology state-of-the-art paper: impact of molecular mechanisms on clinical arrhythmia management. Clin Res Cardiol 2018; 108:577-599. [PMID: 30306295 DOI: 10.1007/s00392-018-1377-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 09/24/2018] [Indexed: 12/19/2022]
Abstract
Cardiac arrhythmias remain a common challenge and are associated with significant morbidity and mortality. Effective and safe rhythm control strategies are a primary, yet unmet need in everyday clinical practice. Despite significant pharmacological and technological advances, including catheter ablation and device-based therapies, the development of more effective alternatives is of significant interest to increase quality of life and to reduce symptom burden, hospitalizations and mortality. The mechanistic understanding of pathophysiological pathways underlying cardiac arrhythmias has advanced profoundly, opening up novel avenues for mechanism-based therapeutic approaches. Current management of arrhythmias, however, is primarily guided by clinical and demographic characteristics of patient groups as opposed to individual, patient-specific mechanisms and pheno-/genotyping. With this state-of-the-art paper, the Working Group on Cellular Electrophysiology of the German Cardiac Society aims to close the gap between advanced molecular understanding and clinical decision-making in cardiac electrophysiology. The significance of cellular electrophysiological findings for clinical arrhythmia management constitutes the main focus of this document. Clinically relevant knowledge of pathophysiological pathways of arrhythmias and cellular mechanisms of antiarrhythmic interventions are summarized. Furthermore, the specific molecular background for the initiation and perpetuation of atrial and ventricular arrhythmias and mechanism-based strategies for therapeutic interventions are highlighted. Current "hot topics" in atrial fibrillation are critically appraised. Finally, the establishment and support of cellular and translational electrophysiology programs in clinical rhythmology departments is called for to improve basic-science-guided patient management.
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Affiliation(s)
- Dierk Thomas
- Department of Cardiology, Medical University Hospital, Im Neuenheimer Feld 410, 69120, Heidelberg, Germany. .,HCR (Heidelberg Center for Heart Rhythm Disorders), Heidelberg, Germany. .,DZHK (German Center for Cardiovascular Research), partner site Heidelberg/Mannheim, Heidelberg, Germany.
| | - Torsten Christ
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, Hamburg, Germany
| | - Larissa Fabritz
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK.,Department of Cardiology, UHB NHS Trust, Birmingham, UK.,Department of Cardiovascular Medicine, Division of Rhythmology, University Hospital Münster, Münster, Germany
| | - Andreas Goette
- St. Vincenz-Hospital, Paderborn, Germany.,Working Group: Molecular Electrophysiology, University Hospital Magdeburg, Magdeburg, Germany
| | - Matthias Hammwöhner
- St. Vincenz-Hospital, Paderborn, Germany.,Working Group: Molecular Electrophysiology, University Hospital Magdeburg, Magdeburg, Germany
| | - Jordi Heijman
- Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Essen, Germany.,Cardiovascular Research Institute Maastricht, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Jens Kockskämper
- Biochemical and Pharmacological Center (BPC) Marburg, Institute of Pharmacology and Clinical Pharmacy, University of Marburg, Marburg, Germany
| | - Dominik Linz
- Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute, University of Adelaide and Royal Adelaide Hospital, Adelaide, SA, Australia.,Experimental Electrophysiology, University Hospital of Saarland, Homburg, Saar, Germany
| | - Katja E Odening
- Department of Cardiology and Angiology I, Heart Center University of Freiburg, Freiburg, Germany.,Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Institute for Experimental Cardiovascular Medicine, Heart Center University of Freiburg, Freiburg, Germany
| | - Patrick A Schweizer
- Department of Cardiology, Medical University Hospital, Im Neuenheimer Feld 410, 69120, Heidelberg, Germany.,HCR (Heidelberg Center for Heart Rhythm Disorders), Heidelberg, Germany.,DZHK (German Center for Cardiovascular Research), partner site Heidelberg/Mannheim, Heidelberg, Germany.,Heidelberg Research Center for Molecular Medicine (HRCMM), Heidelberg, Germany
| | - Reza Wakili
- Department of Cardiology and Vascular Medicine, Medical Faculty, West German Heart Center, University Hospital Essen, Essen, Germany
| | - Niels Voigt
- Institute of Pharmacology and Toxicology, University Medical Center Göttingen, Georg-August University Göttingen, Robert-Koch-Straße 40, 37075, Göttingen, Germany. .,DZHK (German Center for Cardiovascular Research), partner site Göttingen, Göttingen, Germany.
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22
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Behar JA, Rosenberg AA, Weiser-Bitoun I, Shemla O, Alexandrovich A, Konyukhov E, Yaniv Y. PhysioZoo: A Novel Open Access Platform for Heart Rate Variability Analysis of Mammalian Electrocardiographic Data. Front Physiol 2018; 9:1390. [PMID: 30337883 PMCID: PMC6180147 DOI: 10.3389/fphys.2018.01390] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 09/12/2018] [Indexed: 12/19/2022] Open
Abstract
Background: The time variation between consecutive heartbeats is commonly referred to as heart rate variability (HRV). Loss of complexity in HRV has been documented in several cardiovascular diseases and has been associated with an increase in morbidity and mortality. However, the mechanisms that control HRV are not well understood. Animal experiments are the key to investigating this question. However, to date, there are no standard open source tools for HRV analysis of mammalian electrocardiogram (ECG) data and no centralized public databases for researchers to access. Methods: We created an open source software solution specifically designed for HRV analysis from ECG data of multiple mammals, including humans. We also created a set of public databases of mammalian ECG signals (dog, rabbit and mouse) with manually corrected R-peaks (>170,000 annotations) and signal quality annotations. The platform (software and databases) is called PhysioZoo. Results: PhysioZoo makes it possible to load ECG data and perform very accurate R-peak detection (F 1 > 98%). It also allows the user to manually correct the R-peak locations and annotate low signal quality of the underlying ECG. PhysioZoo implements state of the art HRV measures adapted for different mammals (dogs, rabbits, and mice) and allows easy export of all computed measures together with standard data representation figures. PhysioZoo provides databases and standard ranges for all HRV measures computed on healthy, conscious humans, dogs, rabbits, and mice at rest. Study of these measures across different mammals can provide new insights into the complexity of heart rate dynamics across species. Conclusion: PhysioZoo enables the standardization and reproducibility of HRV analysis in mammalian models through its open source code, freely available software, and open access databases. PhysioZoo will support and enable new investigations in mammalian HRV research. The source code and software are available on www.physiozoo.com.
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Affiliation(s)
| | - Aviv A. Rosenberg
- Faculty of Biomedical Engineering, Technion-IIT, Haifa, Israel
- Faculty of Computer Science, Technion-IIT, Haifa, Israel
| | | | - Ori Shemla
- Faculty of Biomedical Engineering, Technion-IIT, Haifa, Israel
| | | | | | - Yael Yaniv
- Faculty of Biomedical Engineering, Technion-IIT, Haifa, Israel
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23
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Zhong M, Rees CM, Terentyev D, Choi BR, Koren G, Karma A. NCX-Mediated Subcellular Ca 2+ Dynamics Underlying Early Afterdepolarizations in LQT2 Cardiomyocytes. Biophys J 2018; 115:1019-1032. [PMID: 30173888 DOI: 10.1016/j.bpj.2018.08.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 07/18/2018] [Accepted: 08/02/2018] [Indexed: 12/12/2022] Open
Abstract
Long QT syndrome type 2 (LQT2) is a congenital disease characterized by loss of function mutations in hERG potassium channels (IKr). LQT2 is associated with fatal ventricular arrhythmias promoted by triggered activity in the form of early afterdepolarizations (EADs). We previously demonstrated that intracellular Ca2+ handling is remodeled in LQT2 myocytes. Remodeling leads to aberrant late RyR-mediated Ca2+ releases that drive forward-mode Na+-Ca2+ exchanger (NCX) current and slow repolarization to promote reopening of L-type calcium channels and EADs. Forward-mode NCX was found to be enhanced despite the fact that these late releases do not significantly alter the whole-cell cytosolic calcium concentration during a vulnerable period of phase 2 of the action potential corresponding to the onset of EADs. Here, we use a multiscale ventricular myocyte model to explain this finding. We show that because the local NCX current is a saturating nonlinear function of the local submembrane calcium concentration, a larger number of smaller-amplitude discrete Ca2+ release events can produce a large increase in whole-cell forward-mode NCX current without increasing significantly the whole-cell cytosolic calcium concentration. Furthermore, we develop novel insights, to our knowledge, into how alterations of stochastic RyR activity at the single-channel level cause late aberrant Ca2+ release events. Experimental measurements in transgenic LTQ2 rabbits confirm the critical arrhythmogenic role of NCX and identify this current as a potential target for antiarrhythmic therapies in LQT2.
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Affiliation(s)
- Mingwang Zhong
- Physics Department and Center for Interdisciplinary Research in Complex Systems, Northeastern University, Boston, Massachusetts
| | - Colin M Rees
- Physics Department and Center for Interdisciplinary Research in Complex Systems, Northeastern University, Boston, Massachusetts
| | - Dmitry Terentyev
- Cardiovascular Research Centre, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, Rhode Island
| | - Bum-Rak Choi
- Cardiovascular Research Centre, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, Rhode Island
| | - Gideon Koren
- Cardiovascular Research Centre, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, Rhode Island
| | - Alain Karma
- Physics Department and Center for Interdisciplinary Research in Complex Systems, Northeastern University, Boston, Massachusetts.
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24
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Behar JA, Rosenberg AA, Shemla O, Murphy KR, Koren G, Billman GE, Yaniv Y. A Universal Scaling Relation for Defining Power Spectral Bands in Mammalian Heart Rate Variability Analysis. Front Physiol 2018; 9:1001. [PMID: 30116198 PMCID: PMC6083004 DOI: 10.3389/fphys.2018.01001] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Accepted: 07/09/2018] [Indexed: 12/11/2022] Open
Abstract
Background: Power spectral density (PSD) analysis of the heartbeat intervals in the three main frequency bands [very low frequency (VLF), low frequency (LF), and high frequency (HF)] provides a quantitative non-invasive tool for assessing the function of the cardiovascular control system. In humans, these frequency bands were standardized following years of empirical evidence. However, no quantitative approach has justified the frequency cutoffs of these bands and how they might be adapted to other mammals. Defining mammal-specific frequency bands is necessary if the PSD analysis of the HR is to be used as a proxy for measuring the autonomic nervous system activity in animal models. Methods: We first describe the distribution of prominent frequency peaks found in the normalized PSD of mammalian data using a Gaussian mixture model while assuming three components corresponding to the traditional VLF, LF and HF bands. We trained the algorithm on a database of human electrocardiogram recordings (n = 18) and validated it on databases of dogs (n = 17) and mice (n = 8). Finally, we tested it to predict the bands for rabbits (n = 4) for the first time. Results: Double-logarithmic analysis demonstrates a scaling law between the GMM-identified cutoff frequencies and the typical heart rate (HRm): fVLF-LF = 0.0037⋅ HR m 0.58 , fLF-HF = 0.0017⋅ HR m 1.01 and fHFup = 0.0128⋅ HR m 0.86 . We found that the band cutoff frequencies and Gaussian mean scale with a power law of 1/4 or 1/8 of the typical body mass (BMm), thus revealing allometric power laws. Conclusion: Our automated data-driven approach allowed us to define the frequency bands in PSD analysis of beat-to-beat time series from different mammals. The scaling law between the band frequency cutoffs and the HRm can be used to approximate the PSD bands in other mammals.
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Affiliation(s)
| | | | - Ori Shemla
- Faculty of Biomedical Engineering, Technion-IIT, Haifa, Israel
| | - Kevin R. Murphy
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, RI, United States
| | - Gideon Koren
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, RI, United States
| | - George E. Billman
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH, United States
| | - Yael Yaniv
- Faculty of Biomedical Engineering, Technion-IIT, Haifa, Israel
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25
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Choi BR, Li W, Terentyev D, Kabakov AY, Zhong M, Rees CM, Terentyeva R, Kim TY, Qu Z, Peng X, Karma A, Koren G. Transient Outward K + Current (I to) Underlies the Right Ventricular Initiation of Polymorphic Ventricular Tachycardia in a Transgenic Rabbit Model of Long-QT Syndrome Type 1. Circ Arrhythm Electrophysiol 2018; 11:e005414. [PMID: 29769222 PMCID: PMC6081959 DOI: 10.1161/circep.117.005414] [Citation(s) in RCA: 12] [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: 05/08/2017] [Accepted: 03/21/2018] [Indexed: 12/29/2022]
Abstract
BACKGROUND Sudden death in long-QT syndrome type 1 (LQT1), an inherited disease caused by loss-of-function mutations in KCNQ1, is triggered by early afterdepolarizations (EADs) that initiate polymorphic ventricular tachycardia (pVT). We investigated ionic mechanisms that underlie pVT in LQT1 using a transgenic rabbit model of LQT1. METHODS Optical mapping, cellular patch clamping, and computer modeling were used to elucidate the mechanisms of EADs in transgenic LQT1 rabbits. RESULTS The results showed that shorter action potential duration in the right ventricle (RV) was associated with focal activity during pVT initiation. RV cardiomyocytes demonstrated higher incidence of EADs under 50 nmol/L isoproterenol. Voltage-clamp studies revealed that the transient outward potassium current (Ito) magnitude was 28% greater in RV associated with KChiP2 but with no differences in terms of calcium-cycling kinetics and other sarcolemmal currents. Perfusing with the Ito blocker 4-aminopyridine changed the initial focal sites of pVT from the RV to the left ventricle, corroborating the role of Ito in pVT initiation. Computer modeling showed that EADs occur preferentially in the RV because of the larger conductance of the slow-inactivating component of Ito, which repolarizes the membrane potential sufficiently rapidly to allow reactivation of ICa,L before IKr has had sufficient time to activate. CONCLUSIONS Ito heterogeneity creates both triggers and an arrhythmogenic substrate in LQT1. In the absence of IKs, Ito interactions with ICa,L and IKr promote EADs in the RV while prolonging action potential duration in the left ventricle. This heterogeneity of action potential enhances dispersion of refractoriness and facilitates conduction blocks that initiate pVTs.
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Affiliation(s)
- Bum-Rak Choi
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence (B.-R.C., W.L., D.T., A.Y.K., R.T., T.Y.K., G.K.).
| | - Weiyan Li
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence (B.-R.C., W.L., D.T., A.Y.K., R.T., T.Y.K., G.K.)
| | - Dmitry Terentyev
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence (B.-R.C., W.L., D.T., A.Y.K., R.T., T.Y.K., G.K.)
| | - Anatoli Y Kabakov
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence (B.-R.C., W.L., D.T., A.Y.K., R.T., T.Y.K., G.K.)
| | - Mingwang Zhong
- Department of Physics, Northeastern University, Boston MA (M.Z., C.M.R., A.K.)
| | - Colin M Rees
- Department of Physics, Northeastern University, Boston MA (M.Z., C.M.R., A.K.)
| | - Radmila Terentyeva
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence (B.-R.C., W.L., D.T., A.Y.K., R.T., T.Y.K., G.K.)
| | - Tae Yun Kim
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence (B.-R.C., W.L., D.T., A.Y.K., R.T., T.Y.K., G.K.)
| | - Zhilin Qu
- Department of Medicine (Cardiology), University of California, Los Angeles (Z.Q.)
| | - Xuwen Peng
- Department of Comparative Medicine, Pennsylvania State University College of Medicine, Hershey (X.P.)
| | - Alain Karma
- Department of Physics, Northeastern University, Boston MA (M.Z., C.M.R., A.K.)
| | - Gideon Koren
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence (B.-R.C., W.L., D.T., A.Y.K., R.T., T.Y.K., G.K.).
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26
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Liu W, Kim TY, Huang X, Liu MB, Koren G, Choi BR, Qu Z. Mechanisms linking T-wave alternans to spontaneous initiation of ventricular arrhythmias in rabbit models of long QT syndrome. J Physiol 2018; 596:1341-1355. [PMID: 29377142 DOI: 10.1113/jp275492] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Accepted: 01/23/2018] [Indexed: 01/23/2023] Open
Abstract
KEY POINTS T-wave alternans (TWA) and T-wave lability (TWL) are precursors of ventricular arrhythmias in long QT syndrome; however, the mechanistic link remains to be clarified. Computer simulations show that action potential duration (APD) prolongation and slowed heart rates promote APD alternans and chaos, manifesting as TWA and TWL, respectively. Regional APD alternans and chaos can exacerbate pre-existing or induce de novo APD dispersion, which combines with enhanced ICa,L to result in premature ventricular complexes (PVCs) originating from the APD gradient region. These PVCs can directly degenerate into re-entrant arrhythmias without the need for an additional tissue substrate or further exacerbate the APD dispersion to cause spontaneous initiation of ventricular arrhythmias. Experiments conducted in transgenic long QT rabbits show that PVC alternans occurs at slow heart rates, preceding spontaneous intuition of ventricular arrhythmias. ABSTRACT T-wave alternans (TWA) and irregular beat-to-beat T-wave variability or T-wave lability (TWL), the ECG manifestations of action potential duration (APD) alternans and variability, are precursors of ventricular arrhythmias in long QT syndromes. TWA and TWL in patients tend to occur at normal heart rates and are usually potentiated by bradycardia. Whether or how TWA and TWL at normal or slow heart rates are causally linked to arrhythmogenesis remains unknown. In the present study, we used computer simulations and experiments of a transgenic rabbit model of long QT syndrome to investigate the underlying mechanisms. Computer simulations showed that APD prolongation and slowed heart rates caused early afterdepolarization-mediated APD alternans and chaos, manifesting as TWA and TWL, respectively. Regional APD alternans and chaos exacerbated pre-existing APD dispersion and, in addition, APD chaos could also induce APD dispersion de novo via chaos desynchronization. Increased APD dispersion, combined with substantially enhanced ICa,L , resulted in a tissue-scale dynamical instability that gave rise to the spontaneous occurrence of unidirectionally propagating premature ventricular complexes (PVCs) originating from the APD gradient region. These PVCs could directly degenerate into re-entrant arrhythmias without the need for an additional tissue substrate or could block the following sinus beat to result in a longer RR interval, which further exacerbated the APD dispersion giving rise to the spontaneous occurrence of ventricular arrhythmias. Slow heart rate-induced PVC alternans was observed in experiments of transgenic LQT2 rabbits under isoproterenol, which was associated with increased APD dispersion and spontaneous occurrence of ventricular arrhythmias, in agreement with the theoretical predictions.
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Affiliation(s)
- Weiqing Liu
- Department of Medicine, University of California, Los Angeles, California, USA.,School of Science, Jiangxi University of Science and Technology, Ganzhou, China
| | - Tae Yun Kim
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, Rhode Island, USA
| | - Xiaodong Huang
- Department of Medicine, University of California, Los Angeles, California, USA.,Department of Physics, South China University of Technology, Guangzhou, China
| | - Michael B Liu
- Department of Medicine, University of California, Los Angeles, California, USA
| | - Gideon Koren
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, Rhode Island, USA
| | - Bum-Rak Choi
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, Rhode Island, USA
| | - Zhilin Qu
- Department of Medicine, University of California, Los Angeles, California, USA.,Department of Biomathematics, University of California, Los Angeles, California, USA
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27
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Dressler FF, Brado J, Odening KE. Electromechanical heterogeneity in the heart : A key to long QT syndrome? Herzschrittmacherther Elektrophysiol 2018; 29:43-47. [PMID: 29234865 DOI: 10.1007/s00399-017-0544-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 11/24/2017] [Indexed: 06/07/2023]
Abstract
In the healthy heart, physiological heterogeneities in structure and in electrical and mechanical activity are crucial for normal, efficient excitation and pumping. Alterations of heterogeneity have been linked to arrhythmogenesis in various cardiac disorders such as long QT syndrome (LQTS). This inherited arrhythmia disorder is caused by mutations in different ion channel genes and is characterized by (heterogeneously) prolonged cardiac repolarization and increased risk for ventricular tachycardia, syncope and sudden cardiac death. Cardiac electrical and mechanical function are not independent of each other but interact in a bidirectional manner by electromechanical and mechano-electrical coupling. Therefore, changes in either process will affect the other. Recent experimental and clinical evidence suggests that LQTS, which is primarily considered an "electrical" disorder, also exhibits features of disturbed mechanical function and heterogeneity, which in turn appears to correlate with the risk of arrhythmia in the individual patient. In this review, we give a short overview of the current knowledge about physiological and pathological, long QT-related electrical and mechanical heterogeneity in the heart. Also, their respective roles for future risk prediction approaches in LQTS are discussed.
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Affiliation(s)
- F F Dressler
- Department of Cardiology and Angiology I, Heart Center, University of Freiburg, Hugstetter Str. 55, 79106, Freiburg, Germany
- Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - J Brado
- Department of Cardiology and Angiology I, Heart Center, University of Freiburg, Hugstetter Str. 55, 79106, Freiburg, Germany
- Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Medizinische Klinik und Poliklinik I, Klinikum der Universität München, Munich, Germany
| | - K E Odening
- Department of Cardiology and Angiology I, Heart Center, University of Freiburg, Hugstetter Str. 55, 79106, Freiburg, Germany.
- Faculty of Medicine, University of Freiburg, Freiburg, Germany.
- Institute for Experimental Cardiovascular Medicine, Heart Center, University of Freiburg, Freiburg, Germany.
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Liu M, Shi G, Zhou A, Rupert CE, Coulombe KLK, Dudley SC. Activation of the unfolded protein response downregulates cardiac ion channels in human induced pluripotent stem cell-derived cardiomyocytes. J Mol Cell Cardiol 2018; 117:62-71. [PMID: 29474817 DOI: 10.1016/j.yjmcc.2018.02.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2017] [Revised: 02/03/2018] [Accepted: 02/14/2018] [Indexed: 10/18/2022]
Abstract
RATIONALE Heart failure is characterized by electrical remodeling that contributes to arrhythmic risk. The unfolded protein response (UPR) is active in heart failure and can decrease protein levels by increasing mRNA decay, accelerating protein degradation, and inhibiting protein translation. OBJECTIVE Therefore, we investigated whether the UPR downregulated cardiac ion channels that may contribute to arrhythmogenic electrical remodeling. METHODS Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) were used to study cardiac ion channels. Action potentials (APs) and ion channel currents were measured by patch clamp recording. The mRNA and protein levels of channels and the UPR effectors were determined by quantitative RT-PCR and Western blotting. Tunicamycin (TM, 50 ng/mL and 5 μg/mL), GSK2606414 (GSK, 300 nmol/L), and 4μ8C (5 μmol/L) were utilized to activate the UPR, inhibit protein kinase-like ER kinase (PERK) and inositol-requiring protein-1 (IRE1), respectively. RESULTS TM-induced activation of the UPR caused significant prolongation of the AP duration (APD) and a reduction of the maximum upstroke velocity (dV/dtmax) of the AP phase 0 in both acute (20-24 h) and chronic treatment (6 days). These changes were explained by reductions in the sodium, L-type calcium, the transient outward and rapidly/slowly activating delayed rectifier potassium currents. Nav1.5, Cav1.2, Kv4.3, and KvLQT1 channels showed concomitant reductions in mRNA and protein levels under activated UPR. Inhibition of PERK or IRE1 shortened the APD and reinstated dV/dtmax. The PERK branch regulated Nav1.5, Kv4.3, hERG, and KvLQT1. The IRE1 branch regulated Nav1.5, hERG, KvLQT1, and Cav1.2. CONCLUSIONS Activated UPR downregulates all major cardiac ion currents and results in electrical remodeling in hiPSC-CMs. Both PERK and IRE1 branches downregulate Nav1.5, hERG, and KvLQT1. The PERK branch specifically downregulates Kv4.3, while the IRE1 branch downregulates Cav1.2. Therefore, the UPR contributed to electrical remodeling, and targeting the UPR might be anti-arrhythmic.
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Affiliation(s)
- Man Liu
- Division of Cardiology, Dept. of Medicine, the Lillehei Heart Institute, University of Minnesota, Minneapolis, MN, United States
| | - Guangbin Shi
- Division of Cardiology, Dept. of Medicine, The Warren Alpert School of Medicine, Brown University; Lifespan Cardiovascular Research Center, Providence, RI, United States
| | - Anyu Zhou
- Division of Cardiology, Dept. of Medicine, The Warren Alpert School of Medicine, Brown University; Lifespan Cardiovascular Research Center, Providence, RI, United States
| | - Cassady E Rupert
- Center for Biomedical Engineering, School of Engineering, Brown University, Providence, RI, United States
| | - Kareen L K Coulombe
- Center for Biomedical Engineering, School of Engineering, Brown University, Providence, RI, United States
| | - Samuel C Dudley
- Division of Cardiology, Dept. of Medicine, the Lillehei Heart Institute, University of Minnesota, Minneapolis, MN, United States.
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29
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Hagiwara M, Shibuta S, Takada K, Kambayashi R, Nakajo M, Aimoto M, Nagasawa Y, Takahara A. The anaesthetized rabbit with acute atrioventricular block provides a new model for detecting drug-induced Torsade de Pointes. Br J Pharmacol 2017; 174:2591-2605. [PMID: 28547743 DOI: 10.1111/bph.13870] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Revised: 05/03/2017] [Accepted: 05/04/2017] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND AND PURPOSE Several rabbit proarrhythmia models have been developed using genetic or pharmacological methods to suppress the slow component of delayed rectifier K+ currents in the ventricle, leading to reduction of the repolarization reserve. Here we have characterized a novel rabbit in vivo proarrhythmia model with severe bradycardia caused by acute atrioventricular block (AVB). EXPERIMENTAL APPROACH Bradycardia was induced in isoflurane-anaesthetized rabbits by inducing AVB with catheter ablation, and the ventricle was electrically driven at 60 beats min-1 throughout the experiment except when extrasystoles appeared. We assessed the effects of two antiarrhythmics, two quinolone antibiotics and one antipsychotic drug, which were chosen as positive drugs (dofetilide, sparfloxacin and haloperidol) and negative drugs (amiodarone and moxifloxacin) for induction of Torsades de Pointes (TdP). KEY RESULTS In our model, TdP arrhythmias appeared with high reproducibility after i.v. dofetilide (10-100 μg·kg-1 ) in five out of six rabbits, sparfloxacin (30 mg·kg-1 ) in three out of six rabbits and haloperidol (0.3-3 mg·kg-1 ) in two out of six rabbits. The lethal arrhythmias repeatedly appeared and were accompanied with prolongation of the QT interval and early afterdepolarization-like phenomena. Neither amiodarone (0.3-10 mg·kg-1 , n = 6) nor moxifloxacin (3-30 mg·kg-1 , n = 6) induced such arrhythmias, even when QT intervals were prolonged. CONCLUSIONS AND IMPLICATIONS These results suggest that our model of the unremodelled and bradycardic heart of the anaesthetized rabbit is a useful test system for the detection of drug-induced TdP arrhythmias.
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Affiliation(s)
- Mihoko Hagiwara
- Department of Pharmacology and Therapeutics, Faculty of Pharmaceutical Sciences, Toho University, Chiba, Japan
| | - Seiji Shibuta
- Department of Pharmacology and Therapeutics, Faculty of Pharmaceutical Sciences, Toho University, Chiba, Japan
| | - Kazuhiro Takada
- Department of Pharmacology and Therapeutics, Faculty of Pharmaceutical Sciences, Toho University, Chiba, Japan
| | - Ryuichi Kambayashi
- Department of Pharmacology and Therapeutics, Faculty of Pharmaceutical Sciences, Toho University, Chiba, Japan
| | - Misako Nakajo
- Department of Pharmacology and Therapeutics, Faculty of Pharmaceutical Sciences, Toho University, Chiba, Japan
| | - Megumi Aimoto
- Department of Pharmacology and Therapeutics, Faculty of Pharmaceutical Sciences, Toho University, Chiba, Japan
| | - Yoshinobu Nagasawa
- Department of Pharmacology and Therapeutics, Faculty of Pharmaceutical Sciences, Toho University, Chiba, Japan
| | - Akira Takahara
- Department of Pharmacology and Therapeutics, Faculty of Pharmaceutical Sciences, Toho University, Chiba, Japan
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30
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Lipták N, Hoffmann OI, Kerekes A, Iski G, Ernszt D, Kvell K, Hiripi L, Bősze Z. Monitoring of Venus transgenic cell migration during pregnancy in non-transgenic rabbits. Transgenic Res 2017; 26:291-299. [PMID: 27832434 PMCID: PMC5350230 DOI: 10.1007/s11248-016-9994-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Accepted: 10/31/2016] [Indexed: 11/29/2022]
Abstract
Cell transfer between mother and fetus were demonstrated previously in several species which possess haemochorial placenta (e.g. in humans, mice, rats, etc.). Here we report the assessment of fetal and maternal microchimerism in non-transgenic (non-TG) New Zealand white rabbits which were pregnant with transgenic (TG) fetuses and in non-TG newborns of TG does. The TG construct, including the Venus fluorophore cDNA driven by a ubiquitous cytomegalovirus enhancer, chicken ß-actin promoter (CAGGS), was previously integrated into the rabbit genome by Sleeping Beauty transposon system. Three different methods [fluorescence microscopy, flow cytometry and quantitative polymerase chain reaction (QPCR)] were employed to search for TG cells and gene products in blood and other tissues of non-TG rabbits. Venus positive peripheral blood mononuclear cells (PBMCs) were not detected in the blood of non-TG littermates or non-TG does by flow cytometry. Tissue samples (liver, kidney, skeletal and heart muscle) also proved to be Venus negative examined with fluorescence microscopy, while histology sections and PBMCs of TG rabbits showed robust Venus protein expression. In case of genomic DNA (gDNA) sourced from tissue samples of non-TG rabbits, CAGGS promoter-specific fragments could not be amplified by QPCR. Our data showed the lack of detectable cell transfer between TG and non-TG rabbits during gestation.
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Affiliation(s)
- N Lipták
- NARIC-Agricultural Biotechnology Institute, Gödöllő, Hungary.
| | - O I Hoffmann
- NARIC-Agricultural Biotechnology Institute, Gödöllő, Hungary
| | - A Kerekes
- NARIC-Agricultural Biotechnology Institute, Gödöllő, Hungary
| | - G Iski
- NARIC-Agricultural Biotechnology Institute, Gödöllő, Hungary
| | - D Ernszt
- Department of Pharmaceutical Biotechnology, University of Pécs, Pécs, Hungary
| | - K Kvell
- Department of Pharmaceutical Biotechnology, University of Pécs, Pécs, Hungary
| | - L Hiripi
- NARIC-Agricultural Biotechnology Institute, Gödöllő, Hungary
| | - Z Bősze
- NARIC-Agricultural Biotechnology Institute, Gödöllő, Hungary
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31
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Edwards AG, Louch WE. Species-Dependent Mechanisms of Cardiac Arrhythmia: A Cellular Focus. CLINICAL MEDICINE INSIGHTS-CARDIOLOGY 2017; 11:1179546816686061. [PMID: 28469490 PMCID: PMC5392019 DOI: 10.1177/1179546816686061] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Accepted: 11/20/2016] [Indexed: 12/17/2022]
Abstract
Although ventricular arrhythmia remains a leading cause of morbidity and mortality, available antiarrhythmic drugs have limited efficacy. Disappointing progress in the development of novel, clinically relevant antiarrhythmic agents may partly be attributed to discrepancies between humans and animal models used in preclinical testing. However, such differences are at present difficult to predict, requiring improved understanding of arrhythmia mechanisms across species. To this end, we presently review interspecies similarities and differences in fundamental cardiomyocyte electrophysiology and current understanding of the mechanisms underlying the generation of afterdepolarizations and reentry. We specifically highlight patent shortcomings in small rodents to reproduce cellular and tissue-level arrhythmia substrate believed to be critical in human ventricle. Despite greater ease of translation from larger animal models, discrepancies remain and interpretation can be complicated by incomplete knowledge of human ventricular physiology due to low availability of explanted tissue. We therefore point to the benefits of mathematical modeling as a translational bridge to understanding and treating human arrhythmia.
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Affiliation(s)
- Andrew G Edwards
- Center for Biomedical Computing, Simula Research Laboratory, Lysaker, Norway.,Center for Cardiological Innovation, Simula Research Laboratory, Lysaker, Norway.,Department of Biosciences, University of Oslo, Oslo, Norway
| | - William E Louch
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,K.G. Jebsen Cardiac Research Centre and Center for Heart Failure Research, University of Oslo, Oslo, Norway
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32
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Chiamvimonvat N, Chen-Izu Y, Clancy CE, Deschenes I, Dobrev D, Heijman J, Izu L, Qu Z, Ripplinger CM, Vandenberg JI, Weiss JN, Koren G, Banyasz T, Grandi E, Sanguinetti MC, Bers DM, Nerbonne JM. Potassium currents in the heart: functional roles in repolarization, arrhythmia and therapeutics. J Physiol 2017; 595:2229-2252. [PMID: 27808412 DOI: 10.1113/jp272883] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 10/11/2016] [Indexed: 12/19/2022] Open
Abstract
This is the second of the two White Papers from the fourth UC Davis Cardiovascular Symposium Systems Approach to Understanding Cardiac Excitation-Contraction Coupling and Arrhythmias (3-4 March 2016), a biennial event that brings together leading experts in different fields of cardiovascular research. The theme of the 2016 symposium was 'K+ channels and regulation', and the objectives of the conference were severalfold: (1) to identify current knowledge gaps; (2) to understand what may go wrong in the diseased heart and why; (3) to identify possible novel therapeutic targets; and (4) to further the development of systems biology approaches to decipher the molecular mechanisms and treatment of cardiac arrhythmias. The sessions of the Symposium focusing on the functional roles of the cardiac K+ channel in health and disease, as well as K+ channels as therapeutic targets, were contributed by Ye Chen-Izu, Gideon Koren, James Weiss, David Paterson, David Christini, Dobromir Dobrev, Jordi Heijman, Thomas O'Hara, Crystal Ripplinger, Zhilin Qu, Jamie Vandenberg, Colleen Clancy, Isabelle Deschenes, Leighton Izu, Tamas Banyasz, Andras Varro, Heike Wulff, Eleonora Grandi, Michael Sanguinetti, Donald Bers, Jeanne Nerbonne and Nipavan Chiamvimonvat as speakers and panel discussants. This article summarizes state-of-the-art knowledge and controversies on the functional roles of cardiac K+ channels in normal and diseased heart. We endeavour to integrate current knowledge at multiple scales, from the single cell to the whole organ levels, and from both experimental and computational studies.
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Affiliation(s)
- Nipavan Chiamvimonvat
- Department of Internal Medicine, University of California, Davis, Genome and Biomedical Science Facility, Rm 6315, Davis, CA, 95616, USA.,Department of Veterans Affairs, Northern California Health Care System, Mather, CA, 95655, USA
| | - Ye Chen-Izu
- Department of Internal Medicine, University of California, Davis, Genome and Biomedical Science Facility, Rm 6315, Davis, CA, 95616, USA.,Department of Pharmacology, University of California, Davis, Genome and Biomedical Science Facility, Rm 3503, Davis, CA, 95616, USA.,Department of Biomedical Engineering, University of California, Davis, Genome and Biomedical Science Facility, Rm 2303, Davis, CA, 95616, USA
| | - Colleen E Clancy
- Department of Pharmacology, University of California, Davis, Genome and Biomedical Science Facility, Rm 3503, Davis, CA, 95616, USA
| | - Isabelle Deschenes
- Department of Physiology and Biophysics, and Biomedical Engineering, Case Western Reserve University, Cleveland, OH, 44109, USA.,Heart and Vascular Research Center, MetroHealth Medical Center, Cleveland, OH, 44109, USA
| | - Dobromir Dobrev
- Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Hufelandstrasse 55, 45122, Essen, Germany
| | - Jordi Heijman
- Department of Cardiology, Cardiovascular Research Institute Maastricht, Faculty of Health, Medicine, and Life Sciences, Maastricht University, Maastricht, The Netherlands
| | - Leighton Izu
- Department of Pharmacology, University of California, Davis, Genome and Biomedical Science Facility, Rm 3503, Davis, CA, 95616, USA
| | - Zhilin Qu
- Division of Cardiology, Cardiovascular Research Laboratory, David Geffen School of Medicine at UCLA, 3645 MRL, Los Angeles, CA, 90095, USA
| | - Crystal M Ripplinger
- Department of Pharmacology, University of California, Davis, Genome and Biomedical Science Facility, Rm 3503, Davis, CA, 95616, USA
| | - Jamie I Vandenberg
- Victor Chang Cardiac Research Institute, 405 Liverpool Street, Darlinghurst, NSW, 2010, Australia
| | - James N Weiss
- Division of Cardiology, Cardiovascular Research Laboratory, David Geffen School of Medicine at UCLA, 3645 MRL, Los Angeles, CA, 90095, USA
| | - Gideon Koren
- Cardiovascular Research Center, Rhode Island Hospital and the Cardiovascular Institute, The Warren Alpert Medical School of Brown University, Providence, RI, 02903, USA
| | - Tamas Banyasz
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Eleonora Grandi
- Department of Pharmacology, University of California, Davis, Genome and Biomedical Science Facility, Rm 3503, Davis, CA, 95616, USA
| | - Michael C Sanguinetti
- Department of Internal Medicine, University of Utah, Nora Eccles Harrison Cardiovascular Research & Training Institute, Salt Lake City, UT, 84112, USA
| | - Donald M Bers
- Department of Pharmacology, University of California, Davis, Genome and Biomedical Science Facility, Rm 3503, Davis, CA, 95616, USA
| | - Jeanne M Nerbonne
- Departments of Developmental Biology and Internal Medicine, Cardiovascular Division, Washington University Medical School, St Louis, MO, 63110, USA
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33
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Bezzerides VJ, Zhang D, Pu WT. Modeling Inherited Arrhythmia Disorders Using Induced Pluripotent Stem Cell-Derived Cardiomyocytes. Circ J 2016; 81:12-21. [PMID: 27916777 DOI: 10.1253/circj.cj-16-1113] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Inherited arrhythmia disorders (IADs) are a group of potentially lethal diseases that remain diagnostic and management challenges. Although the genetic basis for many of these disorders is well known, the pathogenicity of individual mutations and the resulting clinical outcomes are difficult to predict. Treatment options remain imperfect, and optimizing therapy for individual patients can be difficult. Recent advances in the derivation of induced pluripotent stem cells (iPSCs) from patients and creation of genetically engineered human models using CRISPR/Cas9 has the potential to dramatically advance translational arrhythmia research. In this review, we discuss the current state of modeling IADs using human iPSC-derived cardiomyocytes. We also discuss current limitations and areas for further study.
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34
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Grandi E, Sanguinetti MC, Bartos DC, Bers DM, Chen-Izu Y, Chiamvimonvat N, Colecraft HM, Delisle BP, Heijman J, Navedo MF, Noskov S, Proenza C, Vandenberg JI, Yarov-Yarovoy V. Potassium channels in the heart: structure, function and regulation. J Physiol 2016; 595:2209-2228. [PMID: 27861921 DOI: 10.1113/jp272864] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2016] [Accepted: 07/18/2016] [Indexed: 12/22/2022] Open
Abstract
This paper is the outcome of the fourth UC Davis Systems Approach to Understanding Cardiac Excitation-Contraction Coupling and Arrhythmias Symposium, a biannual event that aims to bring together leading experts in subfields of cardiovascular biomedicine to focus on topics of importance to the field. The theme of the 2016 symposium was 'K+ Channels and Regulation'. Experts in the field contributed their experimental and mathematical modelling perspectives and discussed emerging questions, controversies and challenges on the topic of cardiac K+ channels. This paper summarizes the topics of formal presentations and informal discussions from the symposium on the structural basis of voltage-gated K+ channel function, as well as the mechanisms involved in regulation of K+ channel gating, expression and membrane localization. Given the critical role for K+ channels in determining the rate of cardiac repolarization, it is hardly surprising that essentially every aspect of K+ channel function is exquisitely regulated in cardiac myocytes. This regulation is complex and highly interrelated to other aspects of myocardial function. K+ channel regulatory mechanisms alter, and are altered by, physiological challenges, pathophysiological conditions, and pharmacological agents. An accompanying paper focuses on the integrative role of K+ channels in cardiac electrophysiology, i.e. how K+ currents shape the cardiac action potential, and how their dysfunction can lead to arrhythmias, and discusses K+ channel-based therapeutics. A fundamental understanding of K+ channel regulatory mechanisms and disease processes is fundamental to reveal new targets for human therapy.
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Affiliation(s)
- Eleonora Grandi
- Department of Pharmacology, University of California, Davis, Davis, CA, 95616, USA
| | - Michael C Sanguinetti
- Department of Internal Medicine, University of Utah, Nora Eccles Harrison Cardiovascular Research and Training Institute, Salt Lake City, UT, 84112, USA
| | - Daniel C Bartos
- Department of Pharmacology, University of California, Davis, Davis, CA, 95616, USA
| | - Donald M Bers
- Department of Pharmacology, University of California, Davis, Davis, CA, 95616, USA
| | - Ye Chen-Izu
- Department of Pharmacology, University of California, Davis, Davis, CA, 95616, USA.,Department of Internal Medicine, Division of Cardiology, University of California, Davis, CA, 95616, USA
| | - Nipavan Chiamvimonvat
- Department of Internal Medicine, Division of Cardiology, University of California, Davis, CA, 95616, USA
| | - Henry M Colecraft
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY, 10032, USA
| | - Brian P Delisle
- Department of Physiology, University of Kentucky, Lexington, KY, 40536, USA
| | - Jordi Heijman
- Department of Cardiology, Cardiovascular Research Institute Maastricht, Faculty of Health, Medicine, and Life Sciences, Maastricht University, Maastricht, The Netherlands
| | - Manuel F Navedo
- Department of Pharmacology, University of California, Davis, Davis, CA, 95616, USA
| | - Sergei Noskov
- Centre for Molecular Simulation, Department of Biological Sciences, University of Calgary, Calgary, AB, T2N 1N4, Canada
| | - Catherine Proenza
- Department of Physiology and Biophysics, University of Colorado - Anschutz Medical Campus, Denver, CO, 80045, USA
| | - Jamie I Vandenberg
- Victor Chang Cardiac Research Institute, Darlinghurst, NSW, 2010, Australia
| | - Vladimir Yarov-Yarovoy
- Department of Physiology and Membrane Biology, University of California, Davis, CA, 95616, USA
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35
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Huang X, Kim TY, Koren G, Choi BR, Qu Z. Spontaneous initiation of premature ventricular complexes and arrhythmias in type 2 long QT syndrome. Am J Physiol Heart Circ Physiol 2016; 311:H1470-H1484. [PMID: 27765749 DOI: 10.1152/ajpheart.00500.2016] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Accepted: 10/03/2016] [Indexed: 02/07/2023]
Abstract
The occurrence of early afterdepolarizations (EADs) and increased dispersion of repolarization are two known factors for arrhythmogenesis in long QT syndrome. However, increased dispersion of repolarization tends to suppress EADs due to the source-sink effect, and thus how the two competing factors cause initiation of arrhythmias remains incompletely understood. Here we used optical mapping and computer simulation to investigate the mechanisms underlying spontaneous initiation of arrhythmias in type 2 long QT (LQT2) syndrome. In optical mapping experiments of transgenic LQT2 rabbit hearts under isoproterenol, premature ventricular complexes (PVCs) were observed to originate from the steep spatial repolarization gradient (RG) regions and propagated unidirectionally. The same PVC behaviors were demonstrated in computer simulations of tissue models of rabbits. Depending on the heterogeneities, these PVCs could lead to either repetitive focal excitations or reentry without requiring an additional vulnerable substrate. Systematic simulations showed that cellular phase 2 EADs were either suppressed or confined to the long action potential region due to the source-sink effect. Tissue-scale phase 3 EADs and PVCs occurred due to tissue-scale dynamical instabilities caused by RG and enhanced L-type calcium current (ICa,L), occurring under both large and small RG. Presence of cellular EADs was not required but potentiated PVCs when RG was small. We also investigated how other factors affect the dynamical instabilities causing PVCs. Our main conclusion is that tissue-scale dynamical instabilities caused by RG and enhanced ICa,L give rise to both the trigger and the vulnerable substrate simultaneously for spontaneous initiation of arrhythmias in LQT2 syndrome.
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Affiliation(s)
- Xiaodong Huang
- Department of Medicine (Cardiology), David Geffen School of Medicine, University of California, Los Angeles, California.,Department of Physics, South China University of Technology, Guangzhou, China; and
| | - Tae Yun Kim
- Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, Rhode Island
| | - Gideon Koren
- Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, Rhode Island
| | - Bum-Rak Choi
- Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, Rhode Island
| | - Zhilin Qu
- Department of Medicine (Cardiology), David Geffen School of Medicine, University of California, Los Angeles, California; .,Department of Biomathematics, David Geffen School of Medicine, University of California, Los Angeles, California
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36
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Terentyev D, Hamilton S. Regulation of sarcoplasmic reticulum Ca 2+ release by serine-threonine phosphatases in the heart. J Mol Cell Cardiol 2016; 101:156-164. [PMID: 27585747 DOI: 10.1016/j.yjmcc.2016.08.020] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 08/26/2016] [Accepted: 08/27/2016] [Indexed: 12/17/2022]
Abstract
The amount and timing of Ca2+ release from the sarcoplasmic reticulum (SR) during cardiac cycle are the main determinants of cardiac contractility. Reversible phosphorylation of the SR Ca2+ release channel, ryanodine receptor type 2 (RyR2) is the central mechanism of regulation of Ca2+ release in cardiomyocytes. Three major serine-threonine phosphatases including PP1, PP2A and PP2B (calcineurin) have been implicated in modulation of RyR2 function. Changes in expression levels of these phosphatases, their activity and targeting to the RyR2 macromolecular complex were demonstrated in many animal models of cardiac disease and humans and are implicated in cardiac arrhythmia and heart failure. Here we review evidence in support of regulation of RyR2-mediated SR Ca2+ release by serine-threonine phosphatases and the role and mechanisms of dysregulation of phosphatases in various disease states.
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Affiliation(s)
- Dmitry Terentyev
- The Warren Alpert Medical School of Brown University, Rhode Island Hospital, Department of Medicine, Cardiovascular Research Center, United States.
| | - Shanna Hamilton
- Cardiff University, School of Medicine, Wales Heart Research Institute, United Kingdom
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37
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Major P, Baczkó I, Hiripi L, Odening KE, Juhász V, Kohajda Z, Horváth A, Seprényi G, Kovács M, Virág L, Jost N, Prorok J, Ördög B, Doleschall Z, Nattel S, Varró A, Bősze Z. A novel transgenic rabbit model with reduced repolarization reserve: long QT syndrome caused by a dominant-negative mutation of the KCNE1 gene. Br J Pharmacol 2016; 173:2046-61. [PMID: 27076034 DOI: 10.1111/bph.13500] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Revised: 03/25/2016] [Accepted: 04/01/2016] [Indexed: 01/26/2023] Open
Abstract
BACKGROUND AND PURPOSE The reliable assessment of proarrhythmic risk of compounds under development remains an elusive goal. Current safety guidelines focus on the effects of blocking the KCNH2/HERG ion channel-in tissues and animals with intact repolarization. Novel models with better predictive value are needed that more closely reflect the conditions in patients with cardiac remodelling and reduced repolarization reserve. EXPERIMENTAL APPROACH We have developed a model for the long QT syndrome type-5 in rabbits (LQT5 ) with cardiac-specific overexpression of a mutant (G52R) KCNE1 β-subunit of the channel that carries the slow delayed-rectifier K(+) -current (IKs ). ECG parameters, including short-term variability of the QT interval (STVQT ), a biomarker for proarrhythmic risk, and arrhythmia development were recorded. In vivo, arrhythmia susceptibility was evaluated by i.v. administration of the IKr blocker dofetilide. K(+) currents were measured with the patch-clamp technique. KEY RESULTS Patch-clamp studies in ventricular myocytes isolated from LQT5 rabbits revealed accelerated IKs and IKr deactivation kinetics. At baseline, LQT5 animals exhibited slightly but significantly prolonged heart-rate corrected QT index (QTi) and increased STVQT . Dofetilide provoked Torsade-de-Pointes arrhythmia in a greater proportion of LQT5 rabbits, paralleled by a further increase in STVQT . CONCLUSION AND IMPLICATIONS We have created a novel transgenic LQT5 rabbit model with increased susceptibility to drug-induced arrhythmias that may represent a useful model for testing proarrhythmic potential and for investigations of the mechanisms underlying arrhythmias and sudden cardiac death due to repolarization disturbances.
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Affiliation(s)
- Péter Major
- Rabbit Genome and Biomodel Group, NARIC - Agricultural Biotechnology Institute, Gödöllő, Hungary
| | - István Baczkó
- Department of Pharmacology & Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - László Hiripi
- Rabbit Genome and Biomodel Group, NARIC - Agricultural Biotechnology Institute, Gödöllő, Hungary
| | - Katja E Odening
- Department of Cardiology and Angiology I, Heart Center University of Freiburg, Freiburg, Germany
| | - Viktor Juhász
- Department of Pharmacology & Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - Zsófia Kohajda
- Department of Pharmacology & Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - András Horváth
- Department of Pharmacology & Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - György Seprényi
- Department of Biology, University of Szeged, Szeged, Hungary
| | - Mária Kovács
- Department of Pharmacology & Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - László Virág
- Department of Pharmacology & Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - Norbert Jost
- Department of Pharmacology & Pharmacotherapy, University of Szeged, Szeged, Hungary.,MTA-SZTE Research Group of Cardiovascular Pharmacology, Hungarian Academy of Sciences, Szeged, Hungary
| | - János Prorok
- Department of Pharmacology & Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - Balázs Ördög
- Department of Pharmacology & Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - Zoltán Doleschall
- Department of Pathogenetics, National Institute of Oncology, Budapest, Hungary
| | - Stanley Nattel
- Department of Medicine, Montreal Heart Institute, Université de Montréal, Canada.,Department of Pharmacology and Therapeutics, McGill University, Montréal, Canada.,Institute of Pharmacology, West German Heart and Vascular Center, Faculty of Medicine, University Duisburg-Essen, Essen, Germany
| | - András Varró
- Department of Pharmacology & Pharmacotherapy, University of Szeged, Szeged, Hungary.,MTA-SZTE Research Group of Cardiovascular Pharmacology, Hungarian Academy of Sciences, Szeged, Hungary
| | - Zsuzsanna Bősze
- Rabbit Genome and Biomodel Group, NARIC - Agricultural Biotechnology Institute, Gödöllő, Hungary
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Lang CN, Koren G, Odening KE. Transgenic rabbit models to investigate the cardiac ion channel disease long QT syndrome. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2016; 121:142-56. [PMID: 27210307 DOI: 10.1016/j.pbiomolbio.2016.05.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 05/01/2016] [Indexed: 12/13/2022]
Abstract
Long QT syndrome (LQTS) is a rare inherited channelopathy caused mainly by different mutations in genes encoding for cardiac K(+) or Na(+) channels, but can also be caused by commonly used ion-channel-blocking and QT-prolonging drugs, thus affecting a much larger population. To develop novel diagnostic and therapeutic strategies to improve the clinical management of these patients, a thorough understanding of the pathophysiological mechanisms of arrhythmogenesis and potential pharmacological targets is needed. Drug-induced and genetic animal models of various species have been generated and have been instrumental for identifying pro-arrhythmic triggers and important characteristics of the arrhythmogenic substrate in LQTS. However, due to species differences in features of cardiac electrical function, these different models do not entirely recapitulate all aspects of the human disease. In this review, we summarize advantages and shortcomings of different drug-induced and genetically mediated LQTS animal models - focusing on mouse and rabbit models since these represent the most commonly used small animal models for LQTS that can be subjected to genetic manipulation. In particular, we highlight the different aspects of arrhythmogenic mechanisms, pro-arrhythmic triggering factors, anti-arrhythmic agents, and electro-mechanical dysfunction investigated in transgenic LQTS rabbit models and their translational application for the clinical management of LQTS patients in detail. Transgenic LQTS rabbits have been instrumental to increase our understanding of the role of spatial and temporal dispersion of repolarization to provide an arrhythmogenic substrate, genotype-differences in the mechanisms for early afterdepolarization formation and arrhythmia maintenance, mechanisms of hormonal modification of arrhythmogenesis and regional heterogeneities in electro-mechanical dysfunction in LQTS.
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Affiliation(s)
- C N Lang
- Department of Cardiology and Angiology I, University Heart Center Freiburg, Medical Center - University of Freiburg, Germany; Faculty of Medicine, University of Freiburg, Germany
| | - G Koren
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, RI, USA
| | - K E Odening
- Department of Cardiology and Angiology I, University Heart Center Freiburg, Medical Center - University of Freiburg, Germany; Faculty of Medicine, University of Freiburg, Germany.
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Wu W, Sanguinetti MC. Molecular Basis of Cardiac Delayed Rectifier Potassium Channel Function and Pharmacology. Card Electrophysiol Clin 2016; 8:275-84. [PMID: 27261821 DOI: 10.1016/j.ccep.2016.01.002] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Human cardiomyocytes express 3 distinct types of delayed rectifier potassium channels. Human ether-a-go-go-related gene (hERG) channels conduct the rapidly activating current IKr; KCNQ1/KCNE1 channels conduct the slowly activating current IKs; and Kv1.5 channels conduct an ultrarapid activating current IKur. Here the authors provide a general overview of the mechanistic and structural basis of ion selectivity, gating, and pharmacology of the 3 types of cardiac delayed rectifier potassium ion channels. Most blockers bind to S6 residues that line the central cavity of the channel, whereas activators interact with the channel at 4 symmetric binding sites outside the cavity.
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Affiliation(s)
- Wei Wu
- Department of Medicine, Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, 95 South 2000 East, Salt Lake City, UT 84112, USA
| | - Michael C Sanguinetti
- Department of Medicine, Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, 95 South 2000 East, Salt Lake City, UT 84112, USA.
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40
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Odening KE, Koren G, Kirk M. Normalization of QT interval duration in a long QT syndrome patient during pregnancy and the postpartum period due to sex hormone effects on cardiac repolarization. HeartRhythm Case Rep 2016; 2:223-227. [PMID: 28491674 PMCID: PMC5419752 DOI: 10.1016/j.hrcr.2015.12.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Affiliation(s)
- Katja E Odening
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, Rhode Island.,Heart Center University of Freiburg, Department of Cardiology and Angiology I, Freiburg, Germany
| | - Gideon Koren
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, Rhode Island
| | - Malcolm Kirk
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, Rhode Island
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Electro-mechanical dysfunction in long QT syndrome: Role for arrhythmogenic risk prediction and modulation by sex and sex hormones. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2015; 120:255-69. [PMID: 26718598 DOI: 10.1016/j.pbiomolbio.2015.12.010] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 11/26/2015] [Accepted: 12/15/2015] [Indexed: 12/24/2022]
Abstract
Long QT syndrome (LQTS) is a congenital arrhythmogenic channelopathy characterized by impaired cardiac repolarization. Increasing evidence supports the notion that LQTS is not purely an "electrical" disease but rather an "electro-mechanical" disease with regionally heterogeneously impaired electrical and mechanical cardiac function. In the first part, this article reviews current knowledge on electro-mechanical (dys)function in LQTS, clinical consequences of the observed electro-mechanical dysfunction, and potential underlying mechanisms. Since several novel imaging techniques - Strain Echocardiography (SE) and Magnetic Resonance Tissue Phase Mapping (TPM) - are applied in clinical and experimental settings to assess the (regional) mechanical function, advantages of these non-invasive techniques and their feasibility in the clinical routine are particularly highlighted. The second part provides novel insights into sex differences and sex hormone effects on electro-mechanical cardiac function in a transgenic LQT2 rabbit model. Here we demonstrate that female LQT2 rabbits exhibit a prolonged time to diastolic peak - as marker for contraction duration and early relaxation - compared to males. Chronic estradiol-treatment enhances these differences in time to diastolic peak even more and additionally increases the risk for ventricular arrhythmia. Importantly, time to diastolic peak is particularly prolonged in rabbits exhibiting ventricular arrhythmia - regardless of hormone treatment - contrasting with a lack of differences in QT duration between symptomatic and asymptomatic LQT2 rabbits. This indicates the potential added value of the assessment of mechanical dysfunction in future risk stratification of LQTS patients.
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Anneken L, Baumann S, Vigneault P, Biliczki P, Friedrich C, Xiao L, Girmatsion Z, Takac I, Brandes RP, Kissler S, Wiegratz I, Zumhagen S, Stallmeyer B, Hohnloser SH, Klingenheben T, Schulze-Bahr E, Nattel S, Ehrlich JR. Estradiol regulates human QT-interval: acceleration of cardiac repolarization by enhanced KCNH2 membrane trafficking. Eur Heart J 2015; 37:640-50. [PMID: 26271031 DOI: 10.1093/eurheartj/ehv371] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 07/15/2015] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Modulation of cardiac repolarization by sexual hormones is controversial and hormonal effects on ion channels remain largely unknown. In the present translational study, we therefore assessed the relationship between QTc duration and gonadal hormones and studied underlying mechanisms. METHODS AND RESULTS We measured hormone levels and QTc intervals in women during clomiphene stimulation for infertility and women before, during, and after pregnancy. Three heterozygous LQT-2 patients (KCNH2-p.Arg752Pro missense mutation) and two unaffected family members additionally were studied during their menstrual cycles. A comprehensive cellular and molecular analysis was done to identify the mechanisms of hormonal QT-interval regulation. High estradiol levels, but neither progesterone nor estradiol/progesterone ratio, inversely correlated with QTc. Consistent with clinical data, in vitro estradiol stimulation (60 pmol/L, 48 h) enhanced IKCNH2. This increase was mediated by estradiol receptor-α-dependent promotion of KCNH2-channel trafficking to the cell membrane. To study the underlying mechanism, we focused on heat-shock proteins. The heat-shock protein-90 (Hsp90) inhibitor geldanamycin abolished estradiol-induced increase in IKCNH2. Geldanamycin had no effect on KCNH2 transcription or translation; nor did it affect expression of estradiol receptors and chaperones. Estradiol enhanced the physical interaction of KCNH2-channel subunits with heat-shock proteins and augmented ion-channel trafficking to the membrane. CONCLUSION Elevated estradiol levels were associated with shorter QTc intervals in healthy women and female LQT-2 patients. Estradiol acts on KCNH2 channels via enhanced estradiol-receptor-α-mediated Hsp90 interaction, augments membrane trafficking and thereby increases repolarizing current. These results provide mechanistic insights into hormonal control of human ventricular repolarization and open novel therapeutic avenues.
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Affiliation(s)
- Lars Anneken
- Universitätsklinikum, Goethe-Universität, Frankfurt, Germany Universitätsklinikum Erlangen, Erlangen, Germany
| | - Stefan Baumann
- Universitätsklinikum, Goethe-Universität, Frankfurt, Germany Universitätsklinikum Mannheim, Mannheim, Germany
| | - Patrick Vigneault
- Montreal Heart Institute and Université de Montréal, Montréal, Canada
| | - Peter Biliczki
- Universitätsklinikum, Goethe-Universität, Frankfurt, Germany
| | - Corinna Friedrich
- Institute for Genetics of Heart Diseases, University Hospital Münster, Münster, Germany
| | - Ling Xiao
- Montreal Heart Institute and Université de Montréal, Montréal, Canada
| | | | - Ina Takac
- Cardiovascular Physiology, Goethe-Universität, Frankfurt, Germany
| | - Ralf P Brandes
- Cardiovascular Physiology, Goethe-Universität, Frankfurt, Germany
| | - Stefan Kissler
- Universitätsklinikum, Goethe-Universität, Frankfurt, Germany
| | - Inka Wiegratz
- Universitätsklinikum, Goethe-Universität, Frankfurt, Germany Kinderwunschpraxis am Goetheplatz, Frankfurt, Germany
| | - Sven Zumhagen
- Institute for Genetics of Heart Diseases, University Hospital Münster, Münster, Germany
| | - Birgit Stallmeyer
- Institute for Genetics of Heart Diseases, University Hospital Münster, Münster, Germany
| | | | - Thomas Klingenheben
- Universitätsklinikum, Goethe-Universität, Frankfurt, Germany Praxis für Kardiologie, Bonn, Germany
| | - Eric Schulze-Bahr
- Institute for Genetics of Heart Diseases, University Hospital Münster, Münster, Germany
| | - Stanley Nattel
- Montreal Heart Institute and Université de Montréal, Montréal, Canada
| | - Joachim R Ehrlich
- Universitätsklinikum, Goethe-Universität, Frankfurt, Germany Division of Cardiology, St. Josefs-Hospital, Wiesbaden, Germany
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Lau E, Kossidas K, Kim TY, Kunitomo Y, Ziv O, Zhen S, Taylor C, Schofield L, Yammine J, Liu G, Peng X, Qu Z, Koren G, Choi BR. Spatially Discordant Alternans and Arrhythmias in Tachypacing-Induced Cardiac Myopathy in Transgenic LQT1 Rabbits: The Importance of IKs and Ca2+ Cycling. PLoS One 2015; 10:e0122754. [PMID: 25970695 PMCID: PMC4430457 DOI: 10.1371/journal.pone.0122754] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Accepted: 02/12/2015] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Remodeling of cardiac repolarizing currents, such as the downregulation of slowly activating K+ channels (IKs), could underlie ventricular fibrillation (VF) in heart failure (HF). We evaluated the role of Iks remodeling in VF susceptibility using a tachypacing HF model of transgenic rabbits with Long QT Type 1 (LQT1) syndrome. METHODS AND RESULTS LQT1 and littermate control (LMC) rabbits underwent three weeks of tachypacing to induce cardiac myopathy (TICM). In vivo telemetry demonstrated steepening of the QT/RR slope in LQT1 with TICM (LQT1-TICM; pre: 0.26±0.04, post: 0.52±0.01, P<0.05). In vivo electrophysiology showed that LQT1-TICM had higher incidence of VF than LMC-TICM (6 of 11 vs. 3 of 11, respectively). Optical mapping revealed larger APD dispersion (16±4 vs. 38±6 ms, p<0.05) and steep APD restitution in LQT1-TICM compared to LQT1-sham (0.53±0.12 vs. 1.17±0.13, p<0.05). LQT1-TICM developed spatially discordant alternans (DA), which caused conduction block and higher-frequency VF (15±1 Hz in LQT1-TICM vs. 13±1 Hz in LMC-TICM, p<0.05). Ca2+ DA was highly dynamic and preceded voltage DA in LQT1-TICM. Ryanodine abolished DA in 5 out of 8 LQT1-TICM rabbits, demonstrating the importance of Ca2+ in complex DA formation. Computer simulations suggested that HF remodeling caused Ca2+-driven alternans, which was further potentiated in LQT1-TICM due to the lack of IKs. CONCLUSIONS Compared with LMC-TICM, LQT1-TICM rabbits exhibit steepened APD restitution and complex DA modulated by Ca2+. Our results strongly support the contention that the downregulation of IKs in HF increases Ca2+ dependent alternans and thereby the risk of VF.
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Affiliation(s)
- Emily Lau
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, Rhode Island, United States of America
| | - Konstantinos Kossidas
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, Rhode Island, United States of America
| | - Tae Yun Kim
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, Rhode Island, United States of America
| | - Yukiko Kunitomo
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, Rhode Island, United States of America
| | - Ohad Ziv
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, Rhode Island, United States of America
| | - Song Zhen
- Department of Medicine (Cardiology), David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
| | - Chantel Taylor
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, Rhode Island, United States of America
| | - Lorraine Schofield
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, Rhode Island, United States of America
| | - Joe Yammine
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, Rhode Island, United States of America
| | - Gongxin Liu
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, Rhode Island, United States of America
| | - Xuwen Peng
- Department of Comparative Medicine, Pennsylvania State University College of Medicine, Hershey, Pennsylvania, United States of America
| | - Zhilin Qu
- Department of Medicine (Cardiology), David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
| | - Gideon Koren
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, Rhode Island, United States of America
| | - Bum-Rak Choi
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, Rhode Island, United States of America
- * E-mail:
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Fan J, Kitajima S, Watanabe T, Xu J, Zhang J, Liu E, Chen YE. Rabbit models for the study of human atherosclerosis: from pathophysiological mechanisms to translational medicine. Pharmacol Ther 2015; 146:104-19. [PMID: 25277507 PMCID: PMC4304984 DOI: 10.1016/j.pharmthera.2014.09.009] [Citation(s) in RCA: 229] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Accepted: 09/22/2014] [Indexed: 01/09/2023]
Abstract
Laboratory animal models play an important role in the study of human diseases. Using appropriate animals is critical not only for basic research but also for the development of therapeutics and diagnostic tools. Rabbits are widely used for the study of human atherosclerosis. Because rabbits have a unique feature of lipoprotein metabolism (like humans but unlike rodents) and are sensitive to a cholesterol diet, rabbit models have not only provided many insights into the pathogenesis and development of human atherosclerosis but also made a great contribution to translational research. In fact, rabbit was the first animal model used for studying human atherosclerosis, more than a century ago. Currently, three types of rabbit model are commonly used for the study of human atherosclerosis and lipid metabolism: (1) cholesterol-fed rabbits, (2) Watanabe heritable hyperlipidemic rabbits, analogous to human familial hypercholesterolemia due to genetic deficiency of LDL receptors, and (3) genetically modified (transgenic and knock-out) rabbits. Despite their importance, compared with the mouse, the most widely used laboratory animal model nowadays, the use of rabbit models is still limited. In this review, we focus on the features of rabbit lipoprotein metabolism and pathology of atherosclerotic lesions that make it the optimal model for human atherosclerotic disease, especially for the translational medicine. For the sake of clarity, the review is not an attempt to be completely inclusive, but instead attempts to summarize substantial information concisely and provide a guideline for experiments using rabbits.
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Affiliation(s)
- Jianglin Fan
- Department of Molecular Pathology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Yamanashi, Shimokato 1110, Chuo-City 409-3898, Japan.
| | - Shuji Kitajima
- Division of Biological Resources and Development, Analytical Research Center for Experimental Sciences, Saga University, Saga, Japan
| | - Teruo Watanabe
- Division of Biological Resources and Development, Analytical Research Center for Experimental Sciences, Saga University, Saga, Japan
| | - Jie Xu
- Center for Advanced Models for Translational Sciences and Therapeutics, University of Michigan Medical Center, Ann Arbor, MI, USA
| | - Jifeng Zhang
- Center for Advanced Models for Translational Sciences and Therapeutics, University of Michigan Medical Center, Ann Arbor, MI, USA
| | - Enqi Liu
- Research Institute of Atherosclerotic Disease and Laboratory Animal Center, Xi'an Jiaotong University School of Medicine, Xi'an, China
| | - Y Eugene Chen
- Center for Advanced Models for Translational Sciences and Therapeutics, University of Michigan Medical Center, Ann Arbor, MI, USA.
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Campuzano O, Allegue C, Fernandez A, Iglesias A, Brugada R. Determining the pathogenicity of genetic variants associated with cardiac channelopathies. Sci Rep 2015; 5:7953. [PMID: 25608792 PMCID: PMC4302303 DOI: 10.1038/srep07953] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Accepted: 12/22/2014] [Indexed: 01/08/2023] Open
Abstract
Advancements in genetic screening have generated massive amounts of data on genetic variation; however, a lack of clear pathogenic stratification has left most variants classified as being of unknown significance. This is a critical limitation for translating genetic data into clinical practice. Genetic screening is currently recommended in the guidelines for diagnosis and treatment of cardiac channelopathies, which are major contributors to sudden cardiac death in young people. We propose to characterize the pathogenicity of genetic variants associated with cardiac channelopathies using a stratified scoring system. The development of this system was considered by using all of the tools currently available to define pathogenicity. The use of this scoring system could help clinicians to understand the limitations of genetic associations with a disease, and help them better define the role that genetics can have in their clinical routine.
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Affiliation(s)
- Oscar Campuzano
- 1] Cardiovascular Genetics Center, Institut d'Investigació Biomèdica de Girona (IDIBGI) and Universitat de Girona (UdG), Girona, Spain [2] Medical Science Department, School of Medicine, University of Girona, Girona, Spain
| | - Catarina Allegue
- Cardiovascular Genetics Center, Institut d'Investigació Biomèdica de Girona (IDIBGI) and Universitat de Girona (UdG), Girona, Spain
| | - Anna Fernandez
- Cardiovascular Genetics Center, Institut d'Investigació Biomèdica de Girona (IDIBGI) and Universitat de Girona (UdG), Girona, Spain
| | - Anna Iglesias
- Cardiovascular Genetics Center, Institut d'Investigació Biomèdica de Girona (IDIBGI) and Universitat de Girona (UdG), Girona, Spain
| | - Ramon Brugada
- 1] Cardiovascular Genetics Center, Institut d'Investigació Biomèdica de Girona (IDIBGI) and Universitat de Girona (UdG), Girona, Spain [2] Medical Science Department, School of Medicine, University of Girona, Girona, Spain [3] Cardiology Service, Hospital Josep Trueta, Girona, Spain
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Kim TY, Kunitomo Y, Pfeiffer Z, Patel D, Hwang J, Harrison K, Patel B, Jeng P, Ziv O, Lu Y, Peng X, Qu Z, Koren G, Choi BR. Complex excitation dynamics underlie polymorphic ventricular tachycardia in a transgenic rabbit model of long QT syndrome type 1. Heart Rhythm 2015; 12:220-8. [PMID: 25285647 PMCID: PMC4277941 DOI: 10.1016/j.hrthm.2014.10.003] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2014] [Indexed: 11/19/2022]
Abstract
BACKGROUND Long QT syndrome type 1 (LQT1) is a congenital disease arising from a loss of function in the slowly activating delayed potassium current IKs, which causes early afterdepolarizations (EADs) and polymorphic ventricular tachycardia (pVT). OBJECTIVE The purpose of this study was to investigate the mechanisms underlying pVT using a transgenic rabbit model of LQT1. METHODS Hearts were perfused retrogradely, and action potentials were recorded using a voltage-sensitive dye and CMOS cameras. RESULTS Bolus injection of isoproterenol (140 nM) induced pVT initiated by focal excitations from the right ventricle (RV; n = 16 of 18 pVTs). After the pVT was initiated, complex focal excitations occurred in both the RV and the left ventricle, which caused oscillations of the QRS complexes on ECG, consistent with the recent proposal of multiple shifting foci caused by EAD chaos. Moreover, the action potential upstroke in pVT showed a bimodal distribution, demonstrating the coexistence of 2 types of excitation that interacted to produce complex pVT: Na(+) current (INa)-mediated fast conduction and L-type Ca(2+) current (ICa)-mediated slow conduction coexist, manifesting as pVT. Addition of 2 μM tetrodotoxin to reduce INa converted pVT into monomorphic VT. Reducing late INa in computer simulation converted pVT into a single dominant reentry, agreeing with experimental results. CONCLUSION Our study demonstrates that pVT in LQT1 rabbits is initiated by focal excitations from the RV and is maintained by multiple shifting foci in both ventricles. Moreover, wave conduction in pVT exhibits bi-excitability, that is, fast wavefronts driven by INa and slow wavefronts driven by ICa co-exist during pVT.
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Affiliation(s)
- Tae Yun Kim
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, Rhode Island
| | - Yukiko Kunitomo
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, Rhode Island
| | - Zachary Pfeiffer
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, Rhode Island
| | - Divyang Patel
- Cardiovascular Institutes, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Jungmin Hwang
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, Rhode Island; Department of Pharmacology, University of Rhode Island, Kingston, Rhode Island
| | - Kathryn Harrison
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, Rhode Island
| | - Brijesh Patel
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, Rhode Island
| | - Paul Jeng
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, Rhode Island
| | - Ohad Ziv
- Case Western Reserve University, School of Medicine, Cleveland, Ohio
| | - Yichun Lu
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, Rhode Island
| | - Xuwen Peng
- Department of Comparative Medicine, Pennsylvania State University College of Medicine, Hershey, Pennsylvania
| | - Zhilin Qu
- Department of Medicine, University of California, Los Angeles, California
| | - Gideon Koren
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, Rhode Island
| | - Bum-Rak Choi
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, Rhode Island.
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Viatchenko-Karpinski S, Kornyeyev D, El-Bizri N, Budas G, Fan P, Jiang Z, Yang J, Anderson ME, Shryock JC, Chang CP, Belardinelli L, Yao L. Intracellular Na+ overload causes oxidation of CaMKII and leads to Ca2+ mishandling in isolated ventricular myocytes. J Mol Cell Cardiol 2014; 76:247-56. [PMID: 25252177 PMCID: PMC4250389 DOI: 10.1016/j.yjmcc.2014.09.009] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Revised: 07/07/2014] [Accepted: 09/11/2014] [Indexed: 12/19/2022]
Abstract
An increase of late Na(+) current (INaL) in cardiac myocytes can raise the cytosolic Na(+) concentration and is associated with activation of Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) and alterations of mitochondrial metabolism and Ca(2+) handling by sarcoplasmic reticulum (SR). We tested the hypothesis that augmentation of INaL can increase mitochondrial reactive oxygen species (ROS) production and oxidation of CaMKII, resulting in spontaneous SR Ca(2+) release and increased diastolic Ca(2+) in myocytes. Increases of INaL and/or of the cytosolic Na(+) concentration led to mitochondrial ROS production and oxidation of CaMKII to cause dysregulation of Ca(2+) handling in rabbit cardiac myocytes.
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Affiliation(s)
| | | | | | - Grant Budas
- Department of Biology, Gilead Sciences, Fremont, CA 94555, USA
| | - Peidong Fan
- Department of Biology, Gilead Sciences, Fremont, CA 94555, USA
| | - Zhan Jiang
- Department of Biology, Gilead Sciences, Fremont, CA 94555, USA
| | - Jin Yang
- Krannert Institute of Cardiology and Division of Cardiology, Indiana University School of Medicine, Indianapolis, IN 46202, USA; Department of Medicine, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Mark E Anderson
- University of Iowa Carver College of Medicine, Department of Internal Medicine, Iowa City, IA 52242, USA
| | - John C Shryock
- Department of Biology, Gilead Sciences, Fremont, CA 94555, USA
| | - Ching-Pin Chang
- Krannert Institute of Cardiology and Division of Cardiology, Indiana University School of Medicine, Indianapolis, IN 46202, USA; Department of Medicine, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | | | - Lina Yao
- Department of Biology, Gilead Sciences, Fremont, CA 94555, USA.
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Odening KE, Koren G. How do sex hormones modify arrhythmogenesis in long QT syndrome? Sex hormone effects on arrhythmogenic substrate and triggered activity. Heart Rhythm 2014; 11:2107-15. [PMID: 24954242 PMCID: PMC4394187 DOI: 10.1016/j.hrthm.2014.06.023] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2013] [Indexed: 11/28/2022]
Abstract
Gender differences in cardiac repolarization and the arrhythmogenic risk of patients with inherited and acquired long QT syndromes are well appreciated clinically. Enhancing our knowledge of the mechanisms underlying these differences is critical to improve our therapeutic strategies for preventing sudden cardiac death in such patients. This review summarizes the effects of sex hormones on the expression and function of ion channels that control cardiac cell excitation and repolarization as well as key proteins that regulate Ca(2+) dynamics at the cellular level. Moreover, it examines the role of sex hormones in modifying the dynamic spatiotemporal (regional and transmural) heterogeneities in action potential duration (eg, the arrhythmogenic substrate) and the susceptibility to (sympathetic) triggered activity at the tissue, organ, and whole animal levels. Finally, it explores the implications of these effects on the management of patients with LQTS.
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Affiliation(s)
- Katja E Odening
- Department of Cardiology and Angiology I, Heart Center University of Freiburg, Freiburg, Germany.
| | - Gideon Koren
- Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, Rhode Island
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Roder K, Werdich AA, Li W, Liu M, Kim TY, Organ-Darling LE, Moshal KS, Hwang JM, Lu Y, Choi BR, MacRae CA, Koren G. RING finger protein RNF207, a novel regulator of cardiac excitation. J Biol Chem 2014; 289:33730-40. [PMID: 25281747 DOI: 10.1074/jbc.m114.592295] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Two recent studies (Newton-Cheh, C. et al. (2009) Common variants at ten loci influence QT interval duration in the QTGEN Study. Nat. Genet. 41, 399-406 and Pfeufer, A. et al. (2009) Common variants at ten loci modulate the QT interval duration in the QTSCD Study. Nat. Genet. 41, 407-414) identified an association, with genome-wide significance, between a single nucleotide polymorphism within the gene encoding RING finger protein 207 (RNF207) and the QT interval. We sought to determine the role of RNF207 in cardiac electrophysiology. Morpholino knockdown of RNF207 in zebrafish embryos resulted in action potential duration prolongation, occasionally a 2:1 atrioventricular block, and slowing of conduction velocity. Conversely, neonatal rabbit cardiomyocytes infected with RNF207-expressing adenovirus exhibited shortened action potential duration. Using transfections of U-2 OS and HEK293 cells, Western blot analysis and immunocytochemistry data demonstrate that RNF207 and the human ether-a-go-go-related gene (HERG) potassium channel interact and colocalize. Furthermore, RNF207 overexpression significantly elevated total and membrane HERG protein and HERG-encoded current density by ∼30-50%, which was dependent on the intact N-terminal RING domain of RNF207. Finally, coexpression of RNF207 and HSP70 increased HERG expression compared with HSP70 alone. This effect was dependent on the C terminus of RNF207. Taken together, the evidence is strong that RNF207 is an important regulator of action potential duration, likely via effects on HERG trafficking and localization in a heat shock protein-dependent manner.
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Affiliation(s)
- Karim Roder
- From the Cardiovascular Research Center, Division of Cardiology, Department of Medicine, Rhode Island Hospital, Warren Alpert Medical School, Brown University, Providence, Rhode Island 02903
| | - Andreas A Werdich
- the Cardiovascular Division, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, and
| | - Weiyan Li
- From the Cardiovascular Research Center, Division of Cardiology, Department of Medicine, Rhode Island Hospital, Warren Alpert Medical School, Brown University, Providence, Rhode Island 02903
| | - Man Liu
- From the Cardiovascular Research Center, Division of Cardiology, Department of Medicine, Rhode Island Hospital, Warren Alpert Medical School, Brown University, Providence, Rhode Island 02903
| | - Tae Yun Kim
- From the Cardiovascular Research Center, Division of Cardiology, Department of Medicine, Rhode Island Hospital, Warren Alpert Medical School, Brown University, Providence, Rhode Island 02903
| | - Louise E Organ-Darling
- the Department of Biological Sciences, Wellesley College, Wellesley, Massachusetts 02481
| | - Karni S Moshal
- From the Cardiovascular Research Center, Division of Cardiology, Department of Medicine, Rhode Island Hospital, Warren Alpert Medical School, Brown University, Providence, Rhode Island 02903
| | - Jung Min Hwang
- From the Cardiovascular Research Center, Division of Cardiology, Department of Medicine, Rhode Island Hospital, Warren Alpert Medical School, Brown University, Providence, Rhode Island 02903
| | - Yichun Lu
- From the Cardiovascular Research Center, Division of Cardiology, Department of Medicine, Rhode Island Hospital, Warren Alpert Medical School, Brown University, Providence, Rhode Island 02903
| | - Bum-Rak Choi
- From the Cardiovascular Research Center, Division of Cardiology, Department of Medicine, Rhode Island Hospital, Warren Alpert Medical School, Brown University, Providence, Rhode Island 02903
| | - Calum A MacRae
- the Cardiovascular Division, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, and
| | - Gideon Koren
- From the Cardiovascular Research Center, Division of Cardiology, Department of Medicine, Rhode Island Hospital, Warren Alpert Medical School, Brown University, Providence, Rhode Island 02903,
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50
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Terentyev D, Rees CM, Li W, Cooper LL, Jindal HK, Peng X, Lu Y, Terentyeva R, Odening KE, Daley J, Bist K, Choi BR, Karma A, Koren G. Hyperphosphorylation of RyRs underlies triggered activity in transgenic rabbit model of LQT2 syndrome. Circ Res 2014; 115:919-28. [PMID: 25249569 DOI: 10.1161/circresaha.115.305146] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
RATIONALE Loss-of-function mutations in human ether go-go (HERG) potassium channels underlie long QT syndrome type 2 (LQT2) and are associated with fatal ventricular tachyarrhythmia. Previously, most studies focused on plasma membrane-related pathways involved in arrhythmogenesis in long QT syndrome, whereas proarrhythmic changes in intracellular Ca(2+) handling remained unexplored. OBJECTIVE We investigated the remodeling of Ca(2+) homeostasis in ventricular cardiomyocytes derived from transgenic rabbit model of LQT2 to determine whether these changes contribute to triggered activity in the form of early after depolarizations (EADs). METHODS AND RESULTS Confocal Ca(2+) imaging revealed decrease in amplitude of Ca(2+) transients and sarcoplasmic reticulum Ca(2+) content in LQT2 myocytes. Experiments using sarcoplasmic reticulum-entrapped Ca(2+) indicator demonstrated enhanced ryanodine receptor (RyR)-mediated sarcoplasmic reticulum Ca(2+) leak in LQT2 cells. Western blot analyses showed increased phosphorylation of RyR in LQT2 myocytes versus controls. Coimmunoprecipitation experiments demonstrated loss of protein phosphatases type 1 and type 2 from the RyR complex. Stimulation of LQT2 cells with β-adrenergic agonist isoproterenol resulted in prolongation of the plateau of action potentials accompanied by aberrant Ca(2+) releases and EADs, which were abolished by inhibition of Ca(2+)/calmodulin-dependent protein kinase type 2. Computer simulations showed that late aberrant Ca(2+) releases caused by RyR hyperactivity promote EADs and underlie the enhanced triggered activity through increased forward mode of Na(+)/Ca(2+) exchanger type 1. CONCLUSIONS Hyperactive, hyperphosphorylated RyRs because of reduced local phosphatase activity enhance triggered activity in LQT2 syndrome. EADs are promoted by aberrant RyR-mediated Ca(2+) releases that are present despite a reduction of sarcoplasmic reticulum content. Those releases increase forward mode Na(+)/Ca(2+) exchanger type 1, thereby slowing repolarization and enabling L-type Ca(2+) current reactivation.
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Affiliation(s)
- Dmitry Terentyev
- From the Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, Alpert Medical School of Brown University, Providence (D.T., W.L., L.L.C., H.K.J., Y.L., R.T., J.D., K.B., B.-R.C., G.K.); Physics Department, Center for Interdisciplinary Research on Complex Systems, Northeastern University, Boston, MA (C.M.R., A.K.); Department of Comparative Medicine, Pennsylvania State University College of Medicine, Hershey (X.P.); and Department of Cardiology and Angiology I, Heart Center Freiburg University, Freiburg, Germany (K.E.O.).
| | - Colin M Rees
- From the Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, Alpert Medical School of Brown University, Providence (D.T., W.L., L.L.C., H.K.J., Y.L., R.T., J.D., K.B., B.-R.C., G.K.); Physics Department, Center for Interdisciplinary Research on Complex Systems, Northeastern University, Boston, MA (C.M.R., A.K.); Department of Comparative Medicine, Pennsylvania State University College of Medicine, Hershey (X.P.); and Department of Cardiology and Angiology I, Heart Center Freiburg University, Freiburg, Germany (K.E.O.)
| | - Weiyan Li
- From the Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, Alpert Medical School of Brown University, Providence (D.T., W.L., L.L.C., H.K.J., Y.L., R.T., J.D., K.B., B.-R.C., G.K.); Physics Department, Center for Interdisciplinary Research on Complex Systems, Northeastern University, Boston, MA (C.M.R., A.K.); Department of Comparative Medicine, Pennsylvania State University College of Medicine, Hershey (X.P.); and Department of Cardiology and Angiology I, Heart Center Freiburg University, Freiburg, Germany (K.E.O.)
| | - Leroy L Cooper
- From the Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, Alpert Medical School of Brown University, Providence (D.T., W.L., L.L.C., H.K.J., Y.L., R.T., J.D., K.B., B.-R.C., G.K.); Physics Department, Center for Interdisciplinary Research on Complex Systems, Northeastern University, Boston, MA (C.M.R., A.K.); Department of Comparative Medicine, Pennsylvania State University College of Medicine, Hershey (X.P.); and Department of Cardiology and Angiology I, Heart Center Freiburg University, Freiburg, Germany (K.E.O.)
| | - Hitesh K Jindal
- From the Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, Alpert Medical School of Brown University, Providence (D.T., W.L., L.L.C., H.K.J., Y.L., R.T., J.D., K.B., B.-R.C., G.K.); Physics Department, Center for Interdisciplinary Research on Complex Systems, Northeastern University, Boston, MA (C.M.R., A.K.); Department of Comparative Medicine, Pennsylvania State University College of Medicine, Hershey (X.P.); and Department of Cardiology and Angiology I, Heart Center Freiburg University, Freiburg, Germany (K.E.O.)
| | - Xuwen Peng
- From the Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, Alpert Medical School of Brown University, Providence (D.T., W.L., L.L.C., H.K.J., Y.L., R.T., J.D., K.B., B.-R.C., G.K.); Physics Department, Center for Interdisciplinary Research on Complex Systems, Northeastern University, Boston, MA (C.M.R., A.K.); Department of Comparative Medicine, Pennsylvania State University College of Medicine, Hershey (X.P.); and Department of Cardiology and Angiology I, Heart Center Freiburg University, Freiburg, Germany (K.E.O.)
| | - Yichun Lu
- From the Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, Alpert Medical School of Brown University, Providence (D.T., W.L., L.L.C., H.K.J., Y.L., R.T., J.D., K.B., B.-R.C., G.K.); Physics Department, Center for Interdisciplinary Research on Complex Systems, Northeastern University, Boston, MA (C.M.R., A.K.); Department of Comparative Medicine, Pennsylvania State University College of Medicine, Hershey (X.P.); and Department of Cardiology and Angiology I, Heart Center Freiburg University, Freiburg, Germany (K.E.O.)
| | - Radmila Terentyeva
- From the Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, Alpert Medical School of Brown University, Providence (D.T., W.L., L.L.C., H.K.J., Y.L., R.T., J.D., K.B., B.-R.C., G.K.); Physics Department, Center for Interdisciplinary Research on Complex Systems, Northeastern University, Boston, MA (C.M.R., A.K.); Department of Comparative Medicine, Pennsylvania State University College of Medicine, Hershey (X.P.); and Department of Cardiology and Angiology I, Heart Center Freiburg University, Freiburg, Germany (K.E.O.)
| | - Katja E Odening
- From the Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, Alpert Medical School of Brown University, Providence (D.T., W.L., L.L.C., H.K.J., Y.L., R.T., J.D., K.B., B.-R.C., G.K.); Physics Department, Center for Interdisciplinary Research on Complex Systems, Northeastern University, Boston, MA (C.M.R., A.K.); Department of Comparative Medicine, Pennsylvania State University College of Medicine, Hershey (X.P.); and Department of Cardiology and Angiology I, Heart Center Freiburg University, Freiburg, Germany (K.E.O.)
| | - Jean Daley
- From the Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, Alpert Medical School of Brown University, Providence (D.T., W.L., L.L.C., H.K.J., Y.L., R.T., J.D., K.B., B.-R.C., G.K.); Physics Department, Center for Interdisciplinary Research on Complex Systems, Northeastern University, Boston, MA (C.M.R., A.K.); Department of Comparative Medicine, Pennsylvania State University College of Medicine, Hershey (X.P.); and Department of Cardiology and Angiology I, Heart Center Freiburg University, Freiburg, Germany (K.E.O.)
| | - Kamana Bist
- From the Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, Alpert Medical School of Brown University, Providence (D.T., W.L., L.L.C., H.K.J., Y.L., R.T., J.D., K.B., B.-R.C., G.K.); Physics Department, Center for Interdisciplinary Research on Complex Systems, Northeastern University, Boston, MA (C.M.R., A.K.); Department of Comparative Medicine, Pennsylvania State University College of Medicine, Hershey (X.P.); and Department of Cardiology and Angiology I, Heart Center Freiburg University, Freiburg, Germany (K.E.O.)
| | - Bum-Rak Choi
- From the Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, Alpert Medical School of Brown University, Providence (D.T., W.L., L.L.C., H.K.J., Y.L., R.T., J.D., K.B., B.-R.C., G.K.); Physics Department, Center for Interdisciplinary Research on Complex Systems, Northeastern University, Boston, MA (C.M.R., A.K.); Department of Comparative Medicine, Pennsylvania State University College of Medicine, Hershey (X.P.); and Department of Cardiology and Angiology I, Heart Center Freiburg University, Freiburg, Germany (K.E.O.)
| | - Alain Karma
- From the Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, Alpert Medical School of Brown University, Providence (D.T., W.L., L.L.C., H.K.J., Y.L., R.T., J.D., K.B., B.-R.C., G.K.); Physics Department, Center for Interdisciplinary Research on Complex Systems, Northeastern University, Boston, MA (C.M.R., A.K.); Department of Comparative Medicine, Pennsylvania State University College of Medicine, Hershey (X.P.); and Department of Cardiology and Angiology I, Heart Center Freiburg University, Freiburg, Germany (K.E.O.)
| | - Gideon Koren
- From the Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, Alpert Medical School of Brown University, Providence (D.T., W.L., L.L.C., H.K.J., Y.L., R.T., J.D., K.B., B.-R.C., G.K.); Physics Department, Center for Interdisciplinary Research on Complex Systems, Northeastern University, Boston, MA (C.M.R., A.K.); Department of Comparative Medicine, Pennsylvania State University College of Medicine, Hershey (X.P.); and Department of Cardiology and Angiology I, Heart Center Freiburg University, Freiburg, Germany (K.E.O.).
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