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Yang Q, Tadros HJ, Sun B, Bidzimou MT, Ezekian JE, Li F, Ludwig A, Wehrens XH, Landstrom AP. Junctional Ectopic Tachycardia Caused by Junctophilin-2 Expression Silencing Is Selectively Sensitive to Ryanodine Receptor Blockade. JACC Basic Transl Sci 2023; 8:1577-1588. [PMID: 38205351 PMCID: PMC10774596 DOI: 10.1016/j.jacbts.2023.07.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 07/10/2023] [Accepted: 07/10/2023] [Indexed: 01/12/2024]
Abstract
Junctional ectopic tachycardia (JET) is a potentially fatal cardiac arrhythmia. Hcn4:shJph2 mice serve as a model of nodal arrhythmias driven by ryanodine type 2 receptor (RyR2)-mediated Ca2+ leak. EL20 is a small molecule that blocks RyR2 Ca2+ leak. In a novel in vivo model of JET, Hcn4:shJph2 mice demonstrated rapid conversion of JET to sinus rhythm with infusion of EL20. Primary atrioventricular nodal cells demonstrated increased Ca2+ transient oscillation frequency and increased RyR2-mediated stored Ca2+ leak which was normalized by EL20. EL20 was found to be rapidly degraded in mouse and human plasma, making it a potential novel therapy for JET.
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Affiliation(s)
- Qixin Yang
- Division of Cardiology, Department of Pediatrics, Duke University School of Medicine, Durham, North Carolina, USA
- Department of Cardiology, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
| | - Hanna J. Tadros
- Section of Cardiology, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
| | - Bo Sun
- Division of Cardiology, Department of Pediatrics, Duke University School of Medicine, Durham, North Carolina, USA
| | - Minu-Tshyeto Bidzimou
- Division of Cardiology, Department of Pediatrics, Duke University School of Medicine, Durham, North Carolina, USA
| | - Jordan E. Ezekian
- Division of Cardiology, Department of Pediatrics, Duke University School of Medicine, Durham, North Carolina, USA
| | - Feng Li
- Center for Drug Discovery and Department of Pathology and Immunology, Baylor College of Medicine, Houston, Texas, USA
| | - Andreas Ludwig
- Institut für Experimentelle und Klinische Pharmakologie, und Toxikologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Xander H.T. Wehrens
- Section of Cardiology, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
- Cardiovascular Research Institute, Departments of Medicine (Cardiology), Molecular Physiology and Biophysics, and Neuroscience and Center for Space Medicine, Baylor College of Medicine, Houston, Texas, USA
| | - Andrew P. Landstrom
- Division of Cardiology, Department of Pediatrics, Duke University School of Medicine, Durham, North Carolina, USA
- Department of Cell Biology, Duke University School of Medicine, Durham, North Carolina, USA
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He YL, Xu WX, Fang TY, Zeng M. Hyperthyroidism and severe bradycardia: Report of three cases and review of the literature. World J Clin Cases 2023; 11:1549-1559. [PMID: 36926388 PMCID: PMC10011989 DOI: 10.12998/wjcc.v11.i7.1549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 01/13/2023] [Accepted: 02/15/2023] [Indexed: 03/02/2023] Open
Abstract
BACKGROUND Hyperthyroidism often leads to tachycardia, but there are also sporadic reports of hyperthyroidism with severe bradycardia, such as sick sinus syndrome (SSS) and atrioventricular block. These disorders are a challenge for clinicians.
CASE SUMMARY We describe three cases of hyperthyroidism with SSS and found 31 similar cases in a PubMed literature search. Through the analysis of these 34 cases, we found 21 cases of atrioventricular block and 13 cases of SSS, with 67.6% of the patients experiencing bradycardia symptoms. After drug treatment, temporary pacemaker implantation, or anti-hyperthyroidism treatment, the bradycardia of 27 patients (79.4%) was relieved, and the median recovery time was 5.5 (2-8) d. Only 7 cases (20.6%) needed permanent pacemaker implantation.
CONCLUSION Patients with hyperthyroidism should be aware of the risk of severe bradycardia. In most cases, drug treatment or temporary pacemaker placement is recommended for initial treatment. If the bradycardia does not improve after 1 wk, a permanent pacemaker should be implanted.
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Affiliation(s)
- Yang-Li He
- Center of Geriatrics, Hainan General Hospital, Haikou 570311, Hainan Province, China
- Hainan Clinical Research Center for Cardiovascular Disease, Hainan General Hospital, Haikou 570311, Hainan Province, China
- Center of Geriatrics, Hainan Affiliated Hospital of Hainan Medical University, Haikou 570311, Hainan Province, China
| | - Wen-Xing Xu
- Center of Geriatrics, Hainan General Hospital, Haikou 570311, Hainan Province, China
- Hainan Clinical Research Center for Cardiovascular Disease, Hainan General Hospital, Haikou 570311, Hainan Province, China
| | - Tuan-Yu Fang
- Department of Endocrine, Hainan General Hospital, Haikou 570311, Hainan Province, China
| | - Min Zeng
- Center of Geriatrics, Hainan General Hospital, Haikou 570311, Hainan Province, China
- Hainan Clinical Research Center for Cardiovascular Disease, Hainan General Hospital, Haikou 570311, Hainan Province, China
- Center of Geriatrics, Hainan Affiliated Hospital of Hainan Medical University, Haikou 570311, Hainan Province, China
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Wang Q, Wang D, Yan G, Qiao Y, Sun L, Zhu B, Wang X, Tang C. SERCA2a was serotonylated and may regulate sino-atrial node pacemaker activity. Biochem Biophys Res Commun 2016; 480:492-497. [DOI: 10.1016/j.bbrc.2016.10.082] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Accepted: 10/22/2016] [Indexed: 10/20/2022]
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Zhang H, Li RJ, Huang X, Yang Z. Activities of the sinus node pacemaking during the simulated atrial reentry. Comput Assist Surg (Abingdon) 2016. [DOI: 10.1080/24699322.2016.1240307] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Affiliation(s)
- Hong Zhang
- School of Electrical Engineering, Xi'an Jiaotong University, Xi’an, China
| | - Rui-juan Li
- School of Electrical Engineering, Xi'an Jiaotong University, Xi’an, China
| | - Xin Huang
- Cardiology Department, First Hospital Xi’an Jiaotong University, Xi’an, China
| | - Zhao Yang
- Medical School, Xi’an Jiaotong University, Xi’an, China
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Zhang H, Li RJ, Huang X. Role of atrium in automaticity of the sinus node. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2016; 2015:47-50. [PMID: 26736197 DOI: 10.1109/embc.2015.7318297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
As the electrical source of hearts, sino-atrial node cells (SANCs) play significant roles in rhythmic firings. Due to the complex structure and function of SANCs, electrical interactions of SAN and its surrounding atrium has not yet been fully understood. The aim of the present study is to investigate effects of coupling conductance between SAN and atrial cells as well as the ectopic beats in atrium on automaticity of the SAN by computer simulation methods. On the basis of a dynamic mathematical single cell model considering the heterogeneity of central and peripheral SANCs, a two-dimensional inhomogeneous tissue slice including SAN and atrium was developed. The operator splitting method was used to integrate the tissue model. The results demonstrated that the coupling conductance between SAN and atrium had effects on the direction of spontaneous action potential conduction in SAN. Weak coupling resulted in a shift of the earliest pacemaker site from central to peripheral SANCs. Additionally, the ectopic beat-induced excitation in atrium was found to be able to enter into and overdrive suppress the automaticity of SAN. Even if the ectopic beat was delivered after the spontaneous firing had started in central SANCs, the spontaneous conduction toward the periphery could also be suppressed by the retrograde activation from the entering atrial depolarization wave. These findings suggested a direct link between sinus node dysfunction and atrial arrhythmias, and therefore were helpful in explaining the role of atrium in sinus node dysfunction.
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Joung B, Chen PS. Function and dysfunction of human sinoatrial node. Korean Circ J 2015; 45:184-91. [PMID: 26023305 PMCID: PMC4446811 DOI: 10.4070/kcj.2015.45.3.184] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Revised: 03/23/2015] [Accepted: 03/26/2015] [Indexed: 11/11/2022] Open
Abstract
Sinoatrial node (SAN) automaticity is jointly regulated by a voltage (cyclic activation and deactivation of membrane ion channels) and Ca2+ clocks (rhythmic spontaneous sarcoplasmic reticulum Ca2+ release). Using optical mapping in Langendorff-perfused canine right atrium, we previously demonstrated that the β-adrenergic stimulation pushes the leading pacemaker to the superior SAN, which has the fastest activation rate and the most robust late diastolic intracellular calcium (Cai) elevation. Dysfunction of the superior SAN is commonly observed in animal models of heart failure and atrial fibrillation (AF), which are known to be associated with abnormal SAN automaticity. Using the 3D electroanatomic mapping techniques, we demonstrated that superior SAN served as the earliest atrial activation site (EAS) during sympathetic stimulation in healthy humans. In contrast, unresponsiveness of superior SAN to sympathetic stimulation was a characteristic finding in patients with AF and SAN dysfunction, and the 3D electroanatomic mapping technique had better diagnostic sensitivity than corrected SAN recovery time testing. However, both tests have significant limitations in detecting patients with symptomatic sick sinus syndrome. Recently, we reported that the location of the EAS can be predicted by the amplitudes of P-wave in the inferior leads. The inferior P-wave amplitudes can also be used to assess the superior SAN responsiveness to sympathetic stimulation. Inverted or isoelectric P-waves at baseline that fail to normalize during isoproterenol infusion suggest SAN dysfunction. P-wave morphology analyses may be helpful in determining the SAN function in patients at risk of symptomatic sick sinus syndrome.
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Affiliation(s)
- Boyoung Joung
- Division of Cardiology, Department of Medicine, Yonsei University College of Medicine, Seoul, Korea
| | - Peng-Sheng Chen
- The Krannert Institute of Cardiology and the Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA
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Kaneko H, Suzuki S, Goto M, Arita T, Yuzawa Y, Yagi N, Murata N, Kato Y, Kano H, Matsuno S, Otsuka T, Uejima T, Oikawa Y, Sagara K, Nagashima K, Kirigaya H, Sawada H, Aizawa T, Yajima J, Yamashita T. Incidence and Predictors of Rehospitalization of Acute Heart Failure Patients. Int Heart J 2015; 56:219-25. [DOI: 10.1536/ihj.14-290] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- Hidehiro Kaneko
- Department of Cardiovascular Medicine, The Cardiovascular Institute
| | - Shinya Suzuki
- Department of Cardiovascular Medicine, The Cardiovascular Institute
| | - Masato Goto
- Department of Cardiovascular Medicine, The Cardiovascular Institute
| | - Takuto Arita
- Department of Cardiovascular Medicine, The Cardiovascular Institute
| | - Yasufumi Yuzawa
- Department of Cardiovascular Medicine, The Cardiovascular Institute
| | - Naoharu Yagi
- Department of Cardiovascular Medicine, The Cardiovascular Institute
| | - Nobuhiro Murata
- Department of Cardiovascular Medicine, The Cardiovascular Institute
| | - Yuko Kato
- Department of Cardiovascular Medicine, The Cardiovascular Institute
| | - Hiroto Kano
- Department of Cardiovascular Medicine, The Cardiovascular Institute
| | - Shunsuke Matsuno
- Department of Cardiovascular Medicine, The Cardiovascular Institute
| | - Takayuki Otsuka
- Department of Cardiovascular Medicine, The Cardiovascular Institute
| | - Tokuhisa Uejima
- Department of Cardiovascular Medicine, The Cardiovascular Institute
| | - Yuji Oikawa
- Department of Cardiovascular Medicine, The Cardiovascular Institute
| | - Koichi Sagara
- Department of Cardiovascular Medicine, The Cardiovascular Institute
| | | | - Hajime Kirigaya
- Department of Cardiovascular Medicine, The Cardiovascular Institute
| | - Hitoshi Sawada
- Department of Cardiovascular Medicine, The Cardiovascular Institute
| | - Tadanori Aizawa
- Department of Cardiovascular Medicine, The Cardiovascular Institute
| | - Junji Yajima
- Department of Cardiovascular Medicine, The Cardiovascular Institute
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Mira YELA, Muhuyati, Lu WH, He PY, Liu ZQ, Yang YC. TGF-β1 signal pathway in the regulation of inflammation in patients with atrial fibrillation. ASIAN PAC J TROP MED 2014; 6:999-1003. [PMID: 24144036 DOI: 10.1016/s1995-7645(13)60180-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Revised: 10/15/2013] [Accepted: 11/15/2013] [Indexed: 10/26/2022] Open
Abstract
OBJECTIVE To observe the expression changes of inflammatory markers TGF-β1, Smad3 and IL-6 in patients with atrial fibrillation (AF), and to explore the significance of TGF-β1 signaling pathway in the structural remodeling of AF. METHODS The expression of TGF-β1, Smad3 and IL-6 in 50 cases with AF and 30 normal cases were detected by RT-PCR and ELISA. RESULTS The TGF-β1, Smad3 and IL-6 mRNA and protein expression levels in patients with AF were significantly higher than that in the control group (P<0.05), but there was no significantly different between the paroxysmal AF group and the persistent AF group (P>0.05). The TGF-β1mRNA expression in the ⩾ 50 years subgroup was significantly higher than that in the <50 years subgroups, and it was higher in the NYHA III subgroup than in the I/II grade subgroup. It was also higher in the left ventricular ejection fraction (LVEF) <50% subgroup than in LVEF ⩾ 50% group, and it was significantly higher in the AF time ⩾ 36 months subgroup than that in <36 months subgroup (P<0.05). The Smad3 and IL-6 expressions in the in the LVEF <50% subgroup were both high that than that in LVEF ⩾ 50% group, and higher in the AF time ⩾ 36 months subgroup than that in <36 months subgroup (P<0.05). There were a positive correlation between TGF-β1, Smad3 and IL-6 (r=0.687, r=0.547). There were also a positive correlation between Smad3 and IL-6 mRNA (r=0.823). CONCLUSIONS AF is associated with inflammation, and the inflammation is also involved in the fibrillation and sustain of AF. The TGF-β1 signal pathway may be involved in the process of atrial structural remodeling in patients with AF, and iss related with the occurrence and maintenance of AF.
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Affiliation(s)
- Ye Erbo Lati Ali Mira
- Comprehensive Cardiology Department, First Affiliated Hospital of Xinjiang Medical University, Urumqi, Xinjiang 830011, China
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9
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Dobrzynski H, Anderson RH, Atkinson A, Borbas Z, D'Souza A, Fraser JF, Inada S, Logantha SJRJ, Monfredi O, Morris GM, Moorman AFM, Nikolaidou T, Schneider H, Szuts V, Temple IP, Yanni J, Boyett MR. Structure, function and clinical relevance of the cardiac conduction system, including the atrioventricular ring and outflow tract tissues. Pharmacol Ther 2013; 139:260-88. [PMID: 23612425 DOI: 10.1016/j.pharmthera.2013.04.010] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Accepted: 03/28/2013] [Indexed: 01/01/2023]
Abstract
It is now over 100years since the discovery of the cardiac conduction system, consisting of three main parts, the sinus node, the atrioventricular node and the His-Purkinje system. The system is vital for the initiation and coordination of the heartbeat. Over the last decade, immense strides have been made in our understanding of the cardiac conduction system and these recent developments are reviewed here. It has been shown that the system has a unique embryological origin, distinct from that of the working myocardium, and is more extensive than originally thought with additional structures: atrioventricular rings, a third node (so called retroaortic node) and pulmonary and aortic sleeves. It has been shown that the expression of ion channels, intracellular Ca(2+)-handling proteins and gap junction channels in the system is specialised (different from that in the ordinary working myocardium), but appropriate to explain the functioning of the system, although there is continued debate concerning the ionic basis of pacemaking. We are beginning to understand the mechanisms (fibrosis and remodelling of ion channels and related proteins) responsible for dysfunction of the system (bradycardia, heart block and bundle branch block) associated with atrial fibrillation and heart failure and even athletic training. Equally, we are beginning to appreciate how naturally occurring mutations in ion channels cause congenital cardiac conduction system dysfunction. Finally, current therapies, the status of a new therapeutic strategy (use of a specific heart rate lowering drug) and a potential new therapeutic strategy (biopacemaking) are reviewed.
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Shinohara T, Kim D, Joung B, Maruyama M, Vembaiyan K, Back TG, Wayne Chen SR, Chen PS, Lin SF. Carvedilol analog modulates both basal and stimulated sinoatrial node automaticity. Heart Vessels 2013; 29:396-403. [PMID: 23836067 DOI: 10.1007/s00380-013-0378-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Accepted: 06/07/2013] [Indexed: 11/29/2022]
Abstract
The membrane voltage clock and calcium (Ca(2+)) clock jointly regulate sinoatrial node (SAN) automaticity. VK-II-36 is a novel carvedilol analog that suppresses sarcoplasmic reticulum (SR) Ca(2+) release but does not block the β-receptor. The effect of VK-II-36 on SAN function remains unclear. The purpose of this study was to evaluate whether VK-II-36 can influence SAN automaticity by inhibiting the Ca(2+) clock. We simultaneously mapped intracellular Ca(2+) and membrane potential in 24 isolated canine right atriums using previously described criteria of the timing of late diastolic intracellular Ca elevation (LDCAE) relative to the action potential upstroke to detect the Ca(2+) clock. Pharmacological interventions with isoproterenol (ISO), ryanodine, caffeine, and VK-II-36 were performed after baseline recordings. VK-II-36 caused sinus rate downregulation and reduced LDCAE in the pacemaking site under basal conditions (P < 0.01). ISO induced an upward shift of the pacemaking site in SAN and augmented LDCAE in the pacemaking site. ISO also significantly and dose-dependently increased the sinus rate. The treatment of VK-II-36 (30 μmol/l) abolished both the ISO-induced shift of the pacemaking site and augmentation of LDCAE (P < 0.01), and it suppressed the ISO-induced increase in sinus rate (P = 0.02). Our results suggest that the sinus rate may be partly controlled by the Ca(2+) clock via SR Ca(2+) release during β-adrenergic stimulation.
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Affiliation(s)
- Tetsuji Shinohara
- Krannert Institute of Cardiology and the Division of Cardiology, Department of Medicine, Indiana University School of Medicine, 1801 N. Capitol Ave, E 308, Indianapolis, IN, 46202, USA
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11
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Persson AB, Persson PB. Cardiac electrophysiology: what is behind our two-billion heart beats? Acta Physiol (Oxf) 2012; 206:90-3. [PMID: 22943479 DOI: 10.1111/j.1748-1716.2012.02466.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- A. Bondke Persson
- Institute of Vegetative Physiology; Charité-Universitaetsmedizin; Berlin; Germany
| | - P. B. Persson
- Institute of Vegetative Physiology; Charité-Universitaetsmedizin; Berlin; Germany
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12
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Choi EK, Chang PC, Lee YS, Lin SF, Zhu W, Maruyama M, Fishbein MC, Chen Z, Rubart-von der Lohe M, Field LJ, Chen PS. Triggered firing and atrial fibrillation in transgenic mice with selective atrial fibrosis induced by overexpression of TGF-β1. Circ J 2012; 76:1354-62. [PMID: 22447020 DOI: 10.1253/circj.cj-11-1301] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND Calcium transient triggered firing (CTTF) is induced by large intracellular calcium (Ca(i)) transient and short action potential duration (APD). We hypothesized that CTTF underlies the mechanisms of early afterdepolarization (EAD) and spontaneous recurrent atrial fibrillation (AF) in transgenic (Tx) mice with overexpression of transforming growth factor β1 (TGF-β1). METHODS AND RESULTS MHC-TGFcys(33)ser Tx mice develop atrial fibrosis because of elevated levels of TGF-β1. We studied membrane potential and Ca(i)transients of isolated superfused atria from Tx and wild-type (Wt) littermates. Short APD and persistently elevated Ca(i) transients promoted spontaneous repetitive EADs, triggered activity and spontaneous AF after cessation of burst pacing in Tx but not Wt atria (39% vs. 0%, P=0.008). We were able to map optically 4 episodes of spontaneous AF re-initiation. All first and second beats of spontaneous AF originated from the right atrium (4/4, 100%), which is more severely fibrotic than the left atrium. Ryanodine and thapsigargin inhibited spontaneous re-initiation of AF in all 7 Tx atria tested. Western blotting showed no significant changes of calsequestrin or sarco/endoplasmic reticulum Ca(2+)-ATPase 2a. CONCLUSIONS Spontaneous AF may occur in the Tx atrium because of CTTF, characterized by APD shortening, prolonged Ca(i) transient, EAD and triggered activity. Inhibition of Ca(2+) release from the sarcoplasmic reticulum suppressed spontaneous AF. Our results indicate that CTTF is an important arrhythmogenic mechanism in TGF-β1 Tx atria.
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Affiliation(s)
- Eue-Keun Choi
- Krannert Institute of Cardiology and the Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA
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Kurokawa J, Furukawa T. Region- and Condition-Dependence of the Membrane and Ca2+ Clocks in the Sinus Node. Circ J 2012; 76:293-4. [DOI: 10.1253/circj.cj-11-1354] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Junko Kurokawa
- Department of Bio-informational Pharmacology, Medical Research Institute, Tokyo Medical and Dental University
| | - Tetsushi Furukawa
- Department of Bio-informational Pharmacology, Medical Research Institute, Tokyo Medical and Dental University
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14
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Ichikawa T, Sekiguchi T, Kawada S, Koizumi J, Endo J, Yamada Y, Ito C, Sugiyama M, Terachi T, Usui Y, Torigoe K, Imai Y. Study of the Association Between an Anomalous Superior Vena Cava and Horseshoe Kidney. Circ J 2012; 76:1253-8. [DOI: 10.1253/circj.cj-11-0874] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Tamaki Ichikawa
- Department of Radiology, Tokai University School of Medicine
| | | | - Shuichi Kawada
- Department of Radiology, Tokai University School of Medicine
| | - Jun Koizumi
- Department of Radiology, Tokai University School of Medicine
| | - Jun Endo
- Department of Radiology, Tokai University School of Medicine
| | - Yuri Yamada
- Department of Radiology, Tokai University School of Medicine
| | - Chihiro Ito
- Department of Radiology, Tokai University School of Medicine
| | - Makoto Sugiyama
- Department of Radiological Technology, Tokai University School of Medicine
| | | | - Yukio Usui
- Department of Urology, Tokai University School of Medicine
| | - Kojun Torigoe
- Department of Anatomy, Tokai University School of Medicine
| | - Yutaka Imai
- Department of Radiology, Tokai University School of Medicine
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Scull JA, McSpadden LC, Himel HD, Badie N, Bursac N. Single-detector simultaneous optical mapping of V(m) and [Ca(2+)](i) in cardiac monolayers. Ann Biomed Eng 2011; 40:1006-17. [PMID: 22124794 DOI: 10.1007/s10439-011-0478-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2011] [Accepted: 11/17/2011] [Indexed: 11/29/2022]
Abstract
Simultaneous mapping of transmembrane voltage (V(m)) and intracellular Ca(2+) concentration (Ca(i)) has been used for studies of normal and abnormal impulse propagation in cardiac tissues. Existing dual mapping systems typically utilize one excitation and two emission bandwidths, requiring two photodetectors with precise pixel registration. In this study we describe a novel, single-detector mapping system that utilizes two excitation and one emission band for the simultaneous recording of action potentials and calcium transients in monolayers of neonatal rat cardiomyocytes. Cells stained with the Ca(2+)-sensitive dye X-Rhod-1 and the voltage-sensitive dye Di-4-ANEPPS were illuminated by a programmable, multicolor LED matrix. Blue and green LED pulses were flashed 180° out of phase at a rate of 488.3 Hz using a custom-built dual bandpass excitation filter that transmitted blue (482 ± 6 nm) and green (577 ± 31 nm) light. A long-pass emission filter (>605 nm) and a 504-channel photodiode array were used to record combined signals from cardiomyocytes. Green excitation yielded Ca(i) transients without significant crosstalk from V(m). Crosstalk present in V(m) signals obtained with blue excitation was removed by subtracting an appropriately scaled version of the Ca(i) transient. This method was applied to study delay between onsets of action potentials and Ca(i) transients in anisotropic cardiac monolayers.
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Affiliation(s)
- James A Scull
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
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16
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Shinohara T, Park HW, Joung B, Maruyama M, Chua SK, Han S, Shen MJ, Chen PS, Lin SF. Selective sinoatrial node optical mapping and the mechanism of sinus rate acceleration. Circ J 2011; 76:309-16. [PMID: 22094913 DOI: 10.1253/circj.cj-11-0734] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND Studies using isolated sinoatrial node (SAN) cells indicate that rhythmic spontaneous sarcoplasmic reticulum calcium release (Ca clock) plays an important role in SAN automaticity. In the intact SAN, cross-contamination of optical signals from the SAN and the right atrium (RA) prevent the definitive testing of Ca clock hypothesis. The aim of this study was to use a novel approach to selectively mapping the intact SAN to examine the Ca clock mechanism. METHODS AND RESULTS We simultaneously mapped intracellular Ca (Ca(i)) and membrane potential (V(m)) in 10 isolated, Langendorff-perfused normal canine RAs. The excitability of the RA was suppressed with high-potassium Tyrode's solution, allowing selective optical mapping of V(m) and Ca(i) of the SAN. Isoproterenol (ISO, 0.03 µmol/L) decreased the cycle length of the sinus beats, and shifted the leading pacemaker site from the middle or inferior SAN to the superior SAN in all RAs. The Ca(i) upstroke preceded the V(m) in the leading pacemaker site by up to 18 ± 2 ms. ISO-induced changes to SAN were inhibited by ryanodine (3 µmol/L), but not ZD7288 (3 µmol/L), a selective I(f) blocker. CONCLUSIONS We conclude that, in the isolated canine RA, a high extracellular potassium concentration can suppress atrial excitability thus leading to SAN-RA conduction block, allowing selective optical mapping of the intact SAN. Acceleration of Ca cycling in the superior SAN underlies the mechanism of sinus tachycardia during sympathetic stimulation.
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Affiliation(s)
- David S Park
- Leon H. Charney Division of Cardiology, New York University School of Medicine, New York, NY 10016, USA
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18
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Miura M, Hirose M, Endoh H, Wakayama Y, Sugai Y, Nakano M, Fukuda K, Shindoh C, Shirato K, Shimokawa H. Acceleration of Ca2+ waves in monocrotaline-induced right ventricular hypertrophy in the rat. Circ J 2011; 75:1343-9. [PMID: 21467666 DOI: 10.1253/circj.cj-10-1050] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND Triggered arrhythmias arise from delayed afterdepolarizations (DADs), with Ca(2+) waves playing an important role in their formation. In ventricular hypertrophy, however, it remains unclear how Ca(2+) waves change their propagation features and affect arrhythmogenesis. We addressed this important issue in a rat model of hypertrophy. METHODS AND RESULTS Rats were given a subcutaneous injection of 60 mg/kg monocrotaline (MCT-rats) or solvent (Ctr-rats). After 4 weeks, MCT-rats showed high right ventricular (RV) pressure and RV hypertrophy. Trabeculae were dissected from 36 right ventricles. The force was measured using a silicon strain gauge and regional intracellular Ca(2+) ([Ca(2+)](i)) was determined using microinjected fura-2. Reproducible Ca(2+) waves were induced by stimulus trains (2 Hz, 7.5s). MCT-rats showed a higher diastolic [Ca(2+)](i) and faster and larger Ca(2+) waves (P<0.01). The velocity and amplitude of Ca(2+) waves were correlated with the diastolic [Ca(2+)](i) both in the Ctr- and MCT-rats. The velocity of Ca(2+) waves in the MCT-rats was larger at the given amplitude of Ca(2+) waves than that in the Ctr-rats (P < 0.01). The amplitude of DADs was correlated with the velocity and amplitude of Ca(2+) waves in the Ctr- and MCT-rats. CONCLUSIONS The results suggest that an increase in diastolic [Ca(2+)](i) and an increase in Ca(2+) sensitivity of the sarcoplasmic reticulum Ca(2+) release channel accelerate Ca(2+) waves in ventricular hypertrophy, thereby causing arrhythmogenesis.
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Affiliation(s)
- Masahito Miura
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine, Sendai, Japan.
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Tian C, Shao CH, Moore CJ, Kutty S, Walseth T, DeSouza C, Bidasee KR. Gain of function of cardiac ryanodine receptor in a rat model of type 1 diabetes. Cardiovasc Res 2011; 91:300-9. [PMID: 21421556 DOI: 10.1093/cvr/cvr076] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
AIMS Ventricular myocytes isolated from hearts of streptozotocin (STZ)-diabetic rats exhibit increased spontaneous Ca(2+) release. Studies attribute this defect to an enhancement in activity of type 2 ryanodine receptor (RyR2). To date, underlying reasons for RyR2 dysregulation remain undefined. This study assesses whether the responsiveness of RyR2 following stimulation by intrinsic ligands is being altered during experimental type 1 diabetes (T1D). METHODS AND RESULTS M-mode echocardiography established a cardiomyopathy in 8 weeks STZ-diabetic rats. Confocal microscopy confirmed an increase in the spontaneous Ca(2+) release in isolated ventricular myocytes. Western blots revealed no significant change in steady-state levels of the RyR2 protein. When purified to homogeneity and incorporated into planar lipid bilayers, RyR2 from STZ-diabetic rats (dRyR2) exhibited reduced current amplitude at ±35 mV. dRyR2 was also more responsive to intrinsic cytoplasmic activators Ca(2+), adenosine triphosphate, and cyclic adenosine diphosphate ribose and less responsive to the cytoplasmic deactivator Mg(2+). Threshold for the activation of RyR2 by trans (luminal) Ca(2+) was also reduced. These changes were independent of phosphorylation at Ser2808 and Ser2814. Two weeks of insulin treatment starting after 6 weeks of diabetes blunted the phenotype change, indicating that the gain of function is specific to the diabetes and not the result of STZ interacting directly with RyR2. CONCLUSION These data show, for the first time, that RyR2 is acquiring a gain-of-function phenotype independent of its phosphorylation status during T1D and provides new insights for the enhanced spontaneous Ca(2+) release in myocytes from T1D rats.
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Affiliation(s)
- Chengju Tian
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198-5800, USA
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20
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Novák P, Soukup T. Calsequestrin distribution, structure and function, its role in normal and pathological situations and the effect of thyroid hormones. Physiol Res 2011; 60:439-52. [PMID: 21401301 DOI: 10.33549/physiolres.931989] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Calsequestrin is the main calcium binding protein of the sarcoplasmic reticulum, serving as an important regulator of Ca(2+). In mammalian muscles, it exists as a skeletal isoform found in fast- and slow-twitch skeletal muscles and a cardiac isoform expressed in the heart and slow-twitch muscles. Recently, many excellent reviews that summarised in great detail various aspects of the calsequestrin structure, localisation or function both in skeletal and cardiac muscle have appeared. The present review focuses on skeletal muscle: information on cardiac tissue is given, where differences between both tissues are functionally important. The article reviews the known multiple roles of calsequestrin including pathology in order to introduce this topic to the broader scientific community and to stimulate an interest in this protein. Newly we describe our results on the effect of thyroid hormones on skeletal and cardiac calsequestrin expression and discuss them in the context of available literary data on this topic.
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Affiliation(s)
- P Novák
- Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
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21
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Joung B, Park HW, Maruyama M, Tang L, Song J, Han S, Piccirillo G, Weiss JN, Lin SF, Chen PS. Intracellular calcium and the mechanism of anodal supernormal excitability in langendorff perfused rabbit ventricles. Circ J 2011; 75:834-43. [PMID: 21301131 DOI: 10.1253/circj.cj-10-1014] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
BACKGROUND Anodal stimulation hyperpolarizes the cell membrane and increases the intracellular Ca(2+) (Ca(i)) transient. This study tested the hypothesis that the maximum slope of the Ca(i) decline (-(dCa(i)/dt)(max)) corresponds to the timing of anodal dip on the strength-interval curve and the initiation of repetitive responses and ventricular fibrillation (VF) after a premature stimulus (S(2)). METHODS AND RESULTS We simultaneously mapped the membrane potential (V(m)) and Ca(i) in 23 rabbit ventricles. A dip in the anodal strength-interval curve was observed. During the anodal dip, ventricles were captured by anodal break excitation directly under the S(2) electrode. The Ca(i) following anodal stimuli is larger than that following cathodal stimuli. The S(1)-S(2) intervals of the anodal dip (203±10 ms) coincided with the -(dCa(i)/dt)(max) (199±10 ms, P=NS). BAPTA-AM (n=3), inhibition of the electrogenic Na(+)-Ca(2+) exchanger current (I(NCX)) by low extracellular Na(+) (n=3), and combined ryanodine and thapsigargin infusion (n=2) eliminated the anodal supernormality. Strong S(2) during the relative refractory period (n=5) induced 29 repetitive responses and 10 VF episodes. The interval between S(2) and the first non-driven beat was coincidental with the time of -(dCa(i)/dt)(max). CONCLUSIONS Larger Ca(i) transient and I(NCX) activation induced by anodal stimulation produces anodal supernormality. The time of maximum I(NCX) activation is coincidental to the induction of non-driven beats from the Ca(i) sinkhole after a strong premature stimulation.
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Affiliation(s)
- Boyoung Joung
- Krannert Institute of Cardiology and the Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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Current World Literature. Curr Opin Cardiol 2011; 26:71-8. [DOI: 10.1097/hco.0b013e32834294db] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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23
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Affiliation(s)
- Gerd Heusch
- Institut für Pathophysiologie, Universitätsklinikum Essen
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Zhang H, Joung B, Shinohara T, Mei X, Chen PS, Lin SF. Synergistic dual automaticity in sinoatrial node cell and tissue models. Circ J 2010; 74:2079-88. [PMID: 20679733 DOI: 10.1253/circj.cj-10-0265] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
BACKGROUND The mechanism of sinoatrial node (SAN) automaticity is traditionally attributed to membrane ion currents. Recent evidence indicates spontaneous sarcoplasmic reticulum (SR) Ca(2+) cycling also plays an important role. METHODS AND RESULTS A computer simulation on SAN cell and 1D tissue model was performed. In the SAN cells, SR Ca(2+) cycling broadly modulated the sinus rate from 1.74 Hz to 3.87 Hz. Shortening of the junctional SR refilling time and increase of SR Ca(2+) release were responsible for sinus rate acceleration. However, under the fast SR Ca(2+) cycling, decreased L-type Ca(2+) current (I(CaL)) resulted in irregular firing. When Ca(2+) cycling was suppressed, I(f) and I(CaT) both acted to stabilize the pacemaker rhythm, but I(CaT) had less effect than I(f). At the 1D level, the electrical coupling between neighboring cells had little effect on the earliest pacemaker location. The leading pacemaking site always colocalized with the site with the highest SR Ca(2+) cycling rate, but shifted to the site with less inhibited I(CaL). CONCLUSIONS The rate of SR Ca(2+) cycling can effectively and broadly modulate the sinus rate. I(f), I(CaL) and I(CaT) play integral roles to guarantee SAN cell rhythmic firing. The leading pacemaker site is determined by intracellular Ca(2+) dynamics and membrane currents, indicating the synergistic dual automaticity not only exists in single SAN cells, but also at the tissue level.
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Affiliation(s)
- Hong Zhang
- Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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