1
|
Aromolaran KA, Corbin A, Aromolaran AS. Obesity Arrhythmias: Role of IL-6 Trans-Signaling. Int J Mol Sci 2024; 25:8407. [PMID: 39125976 DOI: 10.3390/ijms25158407] [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: 07/07/2024] [Revised: 07/24/2024] [Accepted: 07/29/2024] [Indexed: 08/12/2024] Open
Abstract
Obesity is a chronic disease that is rapidly increasing in prevalence and affects more than 600 million adults worldwide, and this figure is estimated to increase by at least double by 2030. In the United States, more than one-third of the adult population is either overweight or obese. The global obesity epidemic is a major risk factor for the development of life-threatening arrhythmias occurring in patients with long QT, particularly in conditions where multiple heart-rate-corrected QT-interval-prolonging mechanisms are simultaneously present. In obesity, excess dietary fat in adipose tissue stimulates the release of immunomodulatory cytokines such as interleukin (IL)-6, leading to a state of chronic inflammation in patients. Over the last decade, increasing evidence has been found to support IL-6 signaling as a powerful predictor of the severity of heart diseases and increased risk for ventricular arrhythmias. IL-6's pro-inflammatory effects are mediated via trans-signaling and may represent a novel arrhythmogenic risk factor in obese hearts. The first selective inhibitor of IL-6 trans-signaling, olamkicept, has shown encouraging results in phase II clinical studies for inflammatory bowel disease. Nevertheless, the connection between IL-6 trans-signaling and obesity-linked ventricular arrhythmias remains unexplored. Therefore, understanding how IL-6 trans-signaling elicits a cellular pro-arrhythmic phenotype and its use as an anti-arrhythmic target in a model of obesity remain unmet clinical needs.
Collapse
Affiliation(s)
- Kelly A Aromolaran
- Nora Eccles Harrison Cardiovascular Research and Training Institute (CVRTI), University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Andrea Corbin
- Nora Eccles Harrison Cardiovascular Research and Training Institute (CVRTI), University of Utah School of Medicine, Salt Lake City, UT 84112, USA
- Department of Biomedical Engineering, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Ademuyiwa S Aromolaran
- Nora Eccles Harrison Cardiovascular Research and Training Institute (CVRTI), University of Utah School of Medicine, Salt Lake City, UT 84112, USA
- Department of Biomedical Engineering, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
- Department of Surgery, Division of Cardiothoracic Surgery, Nutrition & Integrative Physiology, Biochemistry & Molecular Medicine Program, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| |
Collapse
|
2
|
Birla RK. State of the art in Purkinje bioengineering. Tissue Cell 2024; 90:102467. [PMID: 39053130 DOI: 10.1016/j.tice.2024.102467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Revised: 06/09/2024] [Accepted: 07/08/2024] [Indexed: 07/27/2024]
Abstract
This review article will cover the recent developments in the new evolving field of Purkinje bioengineering and the development of human Purkinje networks. Recent work has progressed to the point of a methodological and systematic process to bioengineer Purkinje networks. This involves the development of 3D models based on human anatomy, followed by the development of tunable biomaterials, and strategies to reprogram stem cells to Purkinje cells. Subsequently, the reprogrammed cells and the biomaterials are coupled to bioengineer Purkinje networks, which are then tested using a small animal injury model. In this article, we discuss this process as a whole and then each step separately. We then describe potential applications of bioengineered Purkinje networks and challenges in the field that need to be overcome to move this field forward. Although the field of Purkinje bioengineering is new and in a state of infancy, it holds tremendous potential, both for therapeutic applications and to develop tools that can be used for disease modeling.
Collapse
Affiliation(s)
- Ravi K Birla
- Laboratory for Regenerative Tissue Repair, Texas Children's Hospital, Houston, TX, USA; Center for Congenital Cardiac Research, Texas Children's Hospital, Houston, TX, USA; Division of Congenital Heart Surgery, Texas Children's Hospital, Houston, TX, USA; Department of Surgery, Baylor College of Medicine, Houston, TX, USA; Division of Pediatric Surgery, Department of Surgery, Texas Children's Hospital, Houston, TX, USA.
| |
Collapse
|
3
|
Zaytseva AK, Kulichik OE, Kostareva AA, Zhorov BS. Biophysical mechanisms of myocardium sodium channelopathies. Pflugers Arch 2024; 476:735-753. [PMID: 38424322 DOI: 10.1007/s00424-024-02930-3] [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: 09/28/2023] [Revised: 02/15/2024] [Accepted: 02/16/2024] [Indexed: 03/02/2024]
Abstract
Genetic variants of gene SCN5A encoding the alpha-subunit of cardiac voltage-gated sodium channel Nav1.5 are associated with various diseases, including long QT syndrome (LQT3), Brugada syndrome (BrS1), and progressive cardiac conduction disease (PCCD). In the last decades, the great progress in understanding molecular and biophysical mechanisms of these diseases has been achieved. The LQT3 syndrome is associated with gain-of-function of sodium channels Nav1.5 due to impaired inactivation, enhanced activation, accelerated recovery from inactivation or the late current appearance. In contrast, BrS1 and PCCD are associated with the Nav1.5 loss-of-function, which in electrophysiological experiments can be manifested as reduced current density, enhanced fast or slow inactivation, impaired activation, or decelerated recovery from inactivation. Genetic variants associated with congenital arrhythmias can also disturb interactions of the Nav1.5 channel with different proteins or drugs and cause unexpected reactions to drug administration. Furthermore, mutations can affect post-translational modifications of the channels and their sensitivity to pH and temperature. Here we briefly review the current knowledge on biophysical mechanisms of LQT3, BrS1 and PCCD. We focus on limitations of studies that use heterologous expression systems and induced pluripotent stem cells (iPSC) derived cardiac myocytes and summarize our understanding of genotype-phenotype relations of SCN5A mutations.
Collapse
Affiliation(s)
- Anastasia K Zaytseva
- Almazov National Medical Research Centre, St. Petersburg, Russia.
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg, Russia.
| | - Olga E Kulichik
- Almazov National Medical Research Centre, St. Petersburg, Russia
| | | | - Boris S Zhorov
- Almazov National Medical Research Centre, St. Petersburg, Russia
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg, Russia
- McMaster University, Hamilton, Canada
| |
Collapse
|
4
|
Mehta A, Chandiramani R, Ghosh B, Asatryan B, Hajra A, Barth AS. Catheter Ablation for Channelopathies: When Is Less More? J Clin Med 2024; 13:2384. [PMID: 38673656 PMCID: PMC11051330 DOI: 10.3390/jcm13082384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Revised: 04/05/2024] [Accepted: 04/11/2024] [Indexed: 04/28/2024] Open
Abstract
Ventricular fibrillation (VF) is a common cause of sudden cardiac death in patients with channelopathies, particularly in the young population. Although pharmacological treatment, cardiac sympathectomy, and implantable cardioverter defibrillators (ICD) have been the mainstay in the management of VF in patients with channelopathies, they are associated with significant adverse effects and complications, leading to poor quality of life. Given these drawbacks, catheter ablation has been proposed as a therapeutic option for patients with channelopathies. Advances in imaging techniques and modern mapping technologies have enabled increased precision in identifying arrhythmia triggers and substrate modification. This has aided our understanding of the underlying pathophysiology of ventricular arrhythmias in channelopathies, highlighting the roles of the Purkinje network and the epicardial right ventricular outflow tract in arrhythmogenesis. This review explores the role of catheter ablation in managing the most common channelopathies (Brugada syndrome, congenital long QT syndrome, short QT syndrome, and catecholaminergic polymorphic ventricular tachycardia). While the initial results for ablation in Brugada syndrome are promising, the long-term efficacy and durability of ablation in different channelopathies require further investigation. Given the genetic and phenotypic heterogeneity of channelopathies, future studies are needed to show whether catheter ablation in patients with channelopathies is associated with a reduction in VF, and psychological distress stemming from recurrent ICD shocks, particularly relative to other available therapeutic options (e.g., quinidine in high-risk Brugada patients).
Collapse
Affiliation(s)
- Adhya Mehta
- Department of Internal Medicine, Albert Einstein College of Medicine/Jacobi Medical Center, Bronx, NY 10461, USA
| | - Rishi Chandiramani
- Department of Medicine, Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Binita Ghosh
- Department of Internal Medicine, SSM Health St. Mary Hospital, St. Louis, MO 63117, USA;
| | - Babken Asatryan
- Department of Medicine, Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Adrija Hajra
- Department of Internal Medicine, Brigham and Women’s Hospital, Boston, MA 02115, USA
| | - Andreas S. Barth
- Department of Medicine, Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| |
Collapse
|
5
|
Kanemaru K, Cranley J, Muraro D, Miranda AMA, Ho SY, Wilbrey-Clark A, Patrick Pett J, Polanski K, Richardson L, Litvinukova M, Kumasaka N, Qin Y, Jablonska Z, Semprich CI, Mach L, Dabrowska M, Richoz N, Bolt L, Mamanova L, Kapuge R, Barnett SN, Perera S, Talavera-López C, Mulas I, Mahbubani KT, Tuck L, Wang L, Huang MM, Prete M, Pritchard S, Dark J, Saeb-Parsy K, Patel M, Clatworthy MR, Hübner N, Chowdhury RA, Noseda M, Teichmann SA. Spatially resolved multiomics of human cardiac niches. Nature 2023; 619:801-810. [PMID: 37438528 PMCID: PMC10371870 DOI: 10.1038/s41586-023-06311-1] [Citation(s) in RCA: 42] [Impact Index Per Article: 42.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Accepted: 06/12/2023] [Indexed: 07/14/2023]
Abstract
The function of a cell is defined by its intrinsic characteristics and its niche: the tissue microenvironment in which it dwells. Here we combine single-cell and spatial transcriptomics data to discover cellular niches within eight regions of the human heart. We map cells to microanatomical locations and integrate knowledge-based and unsupervised structural annotations. We also profile the cells of the human cardiac conduction system1. The results revealed their distinctive repertoire of ion channels, G-protein-coupled receptors (GPCRs) and regulatory networks, and implicated FOXP2 in the pacemaker phenotype. We show that the sinoatrial node is compartmentalized, with a core of pacemaker cells, fibroblasts and glial cells supporting glutamatergic signalling. Using a custom CellPhoneDB.org module, we identify trans-synaptic pacemaker cell interactions with glia. We introduce a druggable target prediction tool, drug2cell, which leverages single-cell profiles and drug-target interactions to provide mechanistic insights into the chronotropic effects of drugs, including GLP-1 analogues. In the epicardium, we show enrichment of both IgG+ and IgA+ plasma cells forming immune niches that may contribute to infection defence. Overall, we provide new clarity to cardiac electro-anatomy and immunology, and our suite of computational approaches can be applied to other tissues and organs.
Collapse
Affiliation(s)
- Kazumasa Kanemaru
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - James Cranley
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Daniele Muraro
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | | | - Siew Yen Ho
- Cardiac Morphology Unit, Royal Brompton Hospital and Imperial College London, London, UK
| | - Anna Wilbrey-Clark
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Jan Patrick Pett
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Krzysztof Polanski
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Laura Richardson
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Monika Litvinukova
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany
| | - Natsuhiko Kumasaka
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Yue Qin
- National Heart and Lung Institute, Imperial College London, London, UK
| | - Zuzanna Jablonska
- National Heart and Lung Institute, Imperial College London, London, UK
| | - Claudia I Semprich
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Lukas Mach
- National Heart and Lung Institute, Imperial College London, London, UK
- Royal Brompton Hospital, London, UK
| | - Monika Dabrowska
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Nathan Richoz
- Molecular Immunity Unit, Department of Medicine, University of Cambridge, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Liam Bolt
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Lira Mamanova
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Rakeshlal Kapuge
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Sam N Barnett
- National Heart and Lung Institute, Imperial College London, London, UK
| | - Shani Perera
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Carlos Talavera-López
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
- Würzburg Institute for Systems Immunology, Max Planck Research Group, Julius-Maximilian-Universität, Würzburg, Germany
| | - Ilaria Mulas
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Krishnaa T Mahbubani
- Department of Surgery, University of Cambridge, and Cambridge Biorepository for Translational Medicine, NIHR Cambridge Biomedical Centre, Cambridge, UK
| | - Liz Tuck
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Lu Wang
- Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, UK
| | - Margaret M Huang
- Department of Surgery, University of Cambridge, and Cambridge Biorepository for Translational Medicine, NIHR Cambridge Biomedical Centre, Cambridge, UK
| | - Martin Prete
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Sophie Pritchard
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - John Dark
- Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, UK
| | - Kourosh Saeb-Parsy
- Department of Surgery, University of Cambridge, and Cambridge Biorepository for Translational Medicine, NIHR Cambridge Biomedical Centre, Cambridge, UK
| | - Minal Patel
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Menna R Clatworthy
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
- Molecular Immunity Unit, Department of Medicine, University of Cambridge, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Norbert Hübner
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany
- Charité-Universitätsmedizin, Berlin, Germany
- German Centre for Cardiovascular Research (DZHK), Partner Site Berlin, Berlin, Germany
| | | | - Michela Noseda
- National Heart and Lung Institute, Imperial College London, London, UK.
| | - Sarah A Teichmann
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK.
- Department of Physics, Cavendish Laboratory, University of Cambridge, Cambridge, UK.
| |
Collapse
|
6
|
Elbrønd VS, Thomsen MB, Isaksen JL, Lunde ED, Vincenti S, Wang T, Tranum-Jensen J, Calloe K. Intramural Purkinje fibers facilitate rapid ventricular activation in the equine heart. Acta Physiol (Oxf) 2023; 237:e13925. [PMID: 36606541 DOI: 10.1111/apha.13925] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 12/11/2022] [Accepted: 01/03/2023] [Indexed: 01/07/2023]
Abstract
BACKGROUND The Purkinje fibers convey the electrical impulses at much higher speed than the working myocardial cells. Thus, the distribution of the Purkinje network is of paramount importance for the timing and coordination of ventricular activation. The Purkinje fibers are found in the subendocardium of all species of mammals, but some mammals also possess an intramural Purkinje fiber network that provides for relatively instantaneous, burst-like activation of the entire ventricular wall, and gives rise to an rS configuration in lead II of the ECG. AIM To relate the topography of the horse heart and the distribution and histology of the conduction system to the pattern of ventricular activation as a mechanism for the unique electrical axis of the equine heart. METHODS The morphology and distribution of the cardiac conduction system was determined by histochemistry. The electrical activity was measured using ECG in the Einthoven and orthogonal configuration. RESULTS The long axis of the equine heart is close to vertical. Outside the nodal regions the conduction system consisted of Purkinje fibers connected by connexin 43 and long, slender parallel running transitional cells. The Purkinje fiber network extended deep into the ventricular walls. ECGs recorded in an orthogonal configuration revealed a mean electrical axis pointing in a cranial-to-left direction indicating ventricular activation in an apex-to-base direction. CONCLUSION The direction of the mean electrical axis in the equine heart is determined by the architecture of the intramural Purkinje network, rather than being a reflection of ventricular mass.
Collapse
Affiliation(s)
- Vibeke S Elbrønd
- Section for Pathobiological Sciences, Department of Veterinary and Animal Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | - Morten B Thomsen
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jonas L Isaksen
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Ester D Lunde
- Section for Pathobiological Sciences, Department of Veterinary and Animal Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | - Stefano Vincenti
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Tobias Wang
- Section for Zoophysiology, Department of Biology, Aarhus University, Aarhus C, Denmark
| | - Jørgen Tranum-Jensen
- Department of Cellular and Molecular Medicine, The Panum Institute, University of Copenhagen, Copenhagen, Denmark
| | - Kirstine Calloe
- Section for Pathobiological Sciences, Department of Veterinary and Animal Sciences, University of Copenhagen, Frederiksberg C, Denmark
| |
Collapse
|
7
|
Kim C, Lever N, Cooper J. Antiarrhythmic drugs and anaesthesia: part 1. mechanisms of cardiac arrhythmias. BJA Educ 2023; 23:8-16. [PMID: 36601026 PMCID: PMC9805968 DOI: 10.1016/j.bjae.2022.11.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/03/2022] [Indexed: 12/12/2022] Open
Affiliation(s)
- C.J. Kim
- Auckland City Hospital (Te Toka Tumai), Auckland, New Zealand
| | - N. Lever
- Auckland City Hospital (Te Toka Tumai), Auckland, New Zealand
- University of Auckland, Auckland, New Zealand
| | - J.O. Cooper
- Auckland City Hospital (Te Toka Tumai), Auckland, New Zealand
| |
Collapse
|
8
|
Bürgisser GM, Heuberger DM, Schaffner N, Giovanoli P, Calcagni M, Buschmann J. Delineation of the healthy rabbit heart by immunohistochemistry - A technical note. Acta Histochem 2023; 125:151993. [PMID: 36584538 DOI: 10.1016/j.acthis.2022.151993] [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: 08/25/2022] [Revised: 12/22/2022] [Accepted: 12/22/2022] [Indexed: 12/29/2022]
Abstract
Heart failure poses a big health problem and may result from obesity, smoking, alcohol and/or growing age. Studying pathological heart tissue demands accurate histological and immunohistochemical stainings in animal models, including chromogenic and fluorescent approaches. Moreover, a reliable set of healthy heart stainings and labeling are required, in order to provide a reference for the pathological situation. Heart and brain tissue of a healthy rabbit were collected, and different histological key steps were compared, such as paraffin embedding after formalin fixation versus cryopreservation; an antigen retrieval (AR) step in processing paraffin sections versus the same procedure without AR; or a chromogenic with a fluorescent detection system, respectively. Using serial sections, we stained the same morphological structure with classic approaches (HE, Masson Goldner Trichrome (GT) and Elastica van Gieson (EL)) and with different markers, including collagen I, collagen III, fibronectin, α-SMA, protease-activated receptor-2 (PAR-2) which is an inflammation-related marker, and ki67 for proliferating cells. Differences between conditions were quantitatively assessed by measuring the color intensity. Generally, cryosections exhibited a more prominent signal intensity in immunohistochemically labeled sections than in paraffin sections, but the strong staining was slurry, which sometimes impeded proper identification of morphological structures, particularly at higher magnifications. In addition, the advantage of an AR step was observed when compared to the condition without AR, where signal intensities were significantly lower. Different stainings of the heart arteries and the myocardium revealed a clear distribution of extracellular matrix components, with prominent collagen III in the artery wall, but an absence of collagen III in the myocardium. Moreover, paraffin-embedded sections provided more distinct structures compared to cryosections after collagen III, ki67, fibronectin, and α-SMA labeling. As for the Purkinje cells that were depicted in the heart and the cerebellum (Purkinje neurons), we found GT staining most suitable to depict them in the heart, while HE as well as EL staining was ideal to depict Purkinje neurons in the cerebellum. In sum, we provide useful reference images with different stainings for researchers using the rabbit heart or brain model. Such images can help to decide which of the immunohistochemical protocols are valuable to reach a specific aim. Recommendations are given for the best visualization of the target structures and specific (immunohistochemical) staining.
Collapse
Affiliation(s)
- Gabriella Meier Bürgisser
- Division of Plastic Surgery and Hand Surgery, University Hospital Zurich, Sternwartstrasse 14, 8091 Zurich, Switzerland
| | - Dorothea M Heuberger
- Institute of Intensive Care Medicine, University Hospital Zurich, Sternwartstrasse 14, 8091 Zurich, Switzerland
| | - Nicola Schaffner
- Division of Plastic Surgery and Hand Surgery, University Hospital Zurich, Sternwartstrasse 14, 8091 Zurich, Switzerland
| | - Pietro Giovanoli
- Division of Plastic Surgery and Hand Surgery, University Hospital Zurich, Sternwartstrasse 14, 8091 Zurich, Switzerland
| | - Maurizio Calcagni
- Division of Plastic Surgery and Hand Surgery, University Hospital Zurich, Sternwartstrasse 14, 8091 Zurich, Switzerland
| | - Johanna Buschmann
- Division of Plastic Surgery and Hand Surgery, University Hospital Zurich, Sternwartstrasse 14, 8091 Zurich, Switzerland.
| |
Collapse
|
9
|
Kelley BP, Chaudry AM, Syed FF. Developing a Mechanistic Approach to Sudden Death Prevention in Mitral Valve Prolapse. J Clin Med 2022; 11:jcm11051285. [PMID: 35268384 PMCID: PMC8910972 DOI: 10.3390/jcm11051285] [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: 12/20/2021] [Revised: 02/23/2022] [Accepted: 02/24/2022] [Indexed: 11/30/2022] Open
Abstract
Sudden cardiac death (SCD) from ventricular fibrillation (VF) can occur in mitral valve prolapse (MVP) in the absence of other comorbidities including mitral regurgitation, heart failure or coronary disease. Although only a small proportion with MVP are at risk, it can affect young, otherwise healthy adults, most commonly premenopausal women, often as the first presentation of MVP. In this review, we discuss arrhythmic mechanisms in MVP and mechanistic approaches for sudden death risk assessment and prevention. We define arrhythmogenic or arrhythmic MVP (AMVP) as MVP associated with complex and frequent ventricular ectopy, and malignant MVP (MMVP) as MVP with high risk of SCD. Factors predisposing to AMVP are myxomatous, bileaflet MVP and mitral annular disjunction (MAD). Data from autopsy, cardiac imaging and electrophysiological studies suggest that ectopy in AMVP is due to inflammation, fibrosis and scarring within the left ventricular (LV) base, LV papillary muscles and Purkinje tissue. Postulated mechanisms include repetitive injury to these regions from systolic papillary muscle stretch and abrupt mitral annular dysmotility (excursion and curling) and diastolic endocardial interaction of redundant mitral leaflets and chordae. Whereas AMVP is seen relatively commonly (up to 30%) in those with MVP, MVP-related SCD is rare (2–4%). However, the proportion at risk (i.e., with MMVP) is unknown. The clustering of cardiac morphological and electrophysiological characteristics similar to AMVP in otherwise idiopathic SCD suggests that MMVP arises when specific arrhythmia modulators allow for VF initiation and perpetuation through action potential prolongation, repolarization heterogeneity and Purkinje triggering. Adequately powered prospective studies are needed to assess strategies for identifying MMVP and the primary prevention of SCD, including ICD implantation, sympathetic modulation and early surgical mitral valve repair. Given the low event rate, a collaborative multicenter approach is essential.
Collapse
Affiliation(s)
- Brian P. Kelley
- Division of Cardiology, University of North Carolina, Chapel Hill, NC 27599, USA;
| | | | - Faisal F. Syed
- Division of Cardiology, University of North Carolina, Chapel Hill, NC 27599, USA;
- Correspondence:
| |
Collapse
|
10
|
Naumova N, Iop L. Bioengineering the Cardiac Conduction System: Advances in Cellular, Gene, and Tissue Engineering for Heart Rhythm Regeneration. Front Bioeng Biotechnol 2021; 9:673477. [PMID: 34409019 PMCID: PMC8365186 DOI: 10.3389/fbioe.2021.673477] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Accepted: 06/24/2021] [Indexed: 01/01/2023] Open
Abstract
Heart rhythm disturbances caused by different etiologies may affect pediatric and adult patients with life-threatening consequences. When pharmacological therapy is ineffective in treating the disturbances, the implantation of electronic devices to control and/or restore normal heart pacing is a unique clinical management option. Although these artificial devices are life-saving, they display many limitations; not least, they do not have any capability to adapt to somatic growth or respond to neuroautonomic physiological changes. A biological pacemaker could offer a new clinical solution for restoring heart rhythms in the conditions of disorder in the cardiac conduction system. Several experimental approaches, such as cell-based, gene-based approaches, and the combination of both, for the generation of biological pacemakers are currently established and widely studied. Pacemaker bioengineering is also emerging as a technology to regenerate nodal tissues. This review analyzes and summarizes the strategies applied so far for the development of biological pacemakers, and discusses current translational challenges toward the first-in-human clinical application.
Collapse
Affiliation(s)
- Nataliia Naumova
- Department of Cardiac Thoracic Vascular Sciences and Public Health, University of Padua, Padua, Italy
| | - Laura Iop
- Department of Cardiac Thoracic Vascular Sciences and Public Health, University of Padua, Padua, Italy
| |
Collapse
|
11
|
Liang D, Xue Z, Xue J, Xie D, Xiong K, Zhou H, Zhang F, Su X, Wang G, Zou Q, Liu Y, Yang J, Ma H, Peng L, Zeng C, Li G, Wang L, Chen YH. Sinoatrial node pacemaker cells share dominant biological properties with glutamatergic neurons. Protein Cell 2021; 12:545-556. [PMID: 33548033 PMCID: PMC8225718 DOI: 10.1007/s13238-020-00820-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 12/03/2020] [Indexed: 01/09/2023] Open
Abstract
Activation of the heart normally begins in the sinoatrial node (SAN). Electrical impulses spontaneously released by SAN pacemaker cells (SANPCs) trigger the contraction of the heart. However, the cellular nature of SANPCs remains controversial. Here, we report that SANPCs exhibit glutamatergic neuron-like properties. By comparing the single-cell transcriptome of SANPCs with that of cells from primary visual cortex in mouse, we found that SANPCs co-clustered with cortical neurons. Tissue and cellular imaging confirmed that SANPCs contained key elements of glutamatergic neurotransmitter system, expressing genes encoding glutamate synthesis pathway (Gls), ionotropic and metabotropic glutamate receptors (Grina, Gria3, Grm1 and Grm5), and glutamate transporters (Slc17a7). SANPCs highly expressed cell markers of glutamatergic neurons (Snap25 and Slc17a7), whereas Gad1, a marker of GABAergic neurons, was negative. Functional studies revealed that inhibition of glutamate receptors or transporters reduced spontaneous pacing frequency of isolated SAN tissues and spontaneous Ca2+ transients frequency in single SANPC. Collectively, our work suggests that SANPCs share dominant biological properties with glutamatergic neurons, and the glutamatergic neurotransmitter system may act as an intrinsic regulation module of heart rhythm, which provides a potential intervention target for pacemaker cell-associated arrhythmias.
Collapse
Affiliation(s)
- Dandan Liang
- Department of Cardiology, East Hospital, Tongji University School of Medicine, Shanghai, 200120, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, Tongji University School of Medicine, Shanghai, 200120, China.,Institute of Medical Genetics, Tongji University, Shanghai, 200092, China
| | - Zhigang Xue
- Department of Regenerative Medicine, Tongji University School of Medicine, Shanghai, 200092, China.,Reproductive Medicine Center, Tongji Hospital, Tongji University School of Medicine, Shanghai, 200065, China
| | - Jinfeng Xue
- Department of Regenerative Medicine, Tongji University School of Medicine, Shanghai, 200092, China
| | - Duanyang Xie
- Department of Cardiology, East Hospital, Tongji University School of Medicine, Shanghai, 200120, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, Tongji University School of Medicine, Shanghai, 200120, China.,Institute of Medical Genetics, Tongji University, Shanghai, 200092, China
| | - Ke Xiong
- Department of Cardiology, East Hospital, Tongji University School of Medicine, Shanghai, 200120, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, Tongji University School of Medicine, Shanghai, 200120, China.,Institute of Medical Genetics, Tongji University, Shanghai, 200092, China
| | - Huixing Zhou
- Department of Cardiology, East Hospital, Tongji University School of Medicine, Shanghai, 200120, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, Tongji University School of Medicine, Shanghai, 200120, China.,Institute of Medical Genetics, Tongji University, Shanghai, 200092, China
| | - Fulei Zhang
- Department of Cardiology, East Hospital, Tongji University School of Medicine, Shanghai, 200120, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, Tongji University School of Medicine, Shanghai, 200120, China.,Institute of Medical Genetics, Tongji University, Shanghai, 200092, China
| | - Xuling Su
- Department of Cardiology, East Hospital, Tongji University School of Medicine, Shanghai, 200120, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, Tongji University School of Medicine, Shanghai, 200120, China.,Institute of Medical Genetics, Tongji University, Shanghai, 200092, China
| | - Guanghua Wang
- Department of Cardiology, East Hospital, Tongji University School of Medicine, Shanghai, 200120, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, Tongji University School of Medicine, Shanghai, 200120, China.,Institute of Medical Genetics, Tongji University, Shanghai, 200092, China
| | - Qicheng Zou
- Department of Cardiology, East Hospital, Tongji University School of Medicine, Shanghai, 200120, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, Tongji University School of Medicine, Shanghai, 200120, China.,Institute of Medical Genetics, Tongji University, Shanghai, 200092, China
| | - Yi Liu
- Department of Cardiology, East Hospital, Tongji University School of Medicine, Shanghai, 200120, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, Tongji University School of Medicine, Shanghai, 200120, China.,Institute of Medical Genetics, Tongji University, Shanghai, 200092, China
| | - Jian Yang
- Department of Cardiology, East Hospital, Tongji University School of Medicine, Shanghai, 200120, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, Tongji University School of Medicine, Shanghai, 200120, China.,Institute of Medical Genetics, Tongji University, Shanghai, 200092, China
| | - Honghui Ma
- Department of Cardiology, East Hospital, Tongji University School of Medicine, Shanghai, 200120, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, Tongji University School of Medicine, Shanghai, 200120, China.,Institute of Medical Genetics, Tongji University, Shanghai, 200092, China
| | - Luying Peng
- Department of Cardiology, East Hospital, Tongji University School of Medicine, Shanghai, 200120, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, Tongji University School of Medicine, Shanghai, 200120, China.,Institute of Medical Genetics, Tongji University, Shanghai, 200092, China.,Department of Pathology and Pathophysiology, Tongji University School of Medicine, Shanghai, 200092, China
| | - Chunyu Zeng
- Department of Cardiology, Daping Hospital, Chongqing, 400042, China
| | - Gang Li
- Department of Neurology, East Hospital, Tongji University School of Medicine, Shanghai, 200120, China
| | - Li Wang
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100037, China
| | - Yi-Han Chen
- Department of Cardiology, East Hospital, Tongji University School of Medicine, Shanghai, 200120, China. .,Key Laboratory of Arrhythmias of the Ministry of Education of China, Tongji University School of Medicine, Shanghai, 200120, China. .,Institute of Medical Genetics, Tongji University, Shanghai, 200092, China. .,Department of Pathology and Pathophysiology, Tongji University School of Medicine, Shanghai, 200092, China.
| |
Collapse
|
12
|
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.
Collapse
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
| |
Collapse
|
13
|
Imnadze G, Zerm T. Prevention of ventricular fibrillation through de-networking of the Purkinje system: Proof-of-Concept Paper on the Substrate Modification of the Purkinje Network. Pacing Clin Electrophysiol 2019; 42:1285-1290. [PMID: 31424573 PMCID: PMC6852399 DOI: 10.1111/pace.13782] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Revised: 07/02/2019] [Accepted: 07/18/2019] [Indexed: 01/01/2023]
Abstract
INTRODUCTION Sudden cardiac death from ventricular fibrillation (VF) remains a major health problem worldwide. Currently, there are limited treatment options available to patients who suffer from episodes of VF. Because Purkinje fibers have been implicated as a source of initiation of VF, we are presenting the first paper of a series highlighting the promising results of substrate modulation through "De-Networking" of the Purkinje system preventing VF in patients without an alternative ablation strategy. METHODS AND RESULTS We studied 10 consecutive patients (two female) all but one implanted with an ICD with documented VF or fast polymorphic Ventricular tachycardia (VT) (five patients without history of structural heart disease, two with ischemic cardiomyopathy, one with hypertrophic obstructive cardiomyopathy, one with dilated cardiomyopathy, and one with aortic valve disease). After 3D electroanatomical mapping, the left bundle branch (LBB) and left ventricular Purkinje potentials were annotated creating a virtual triangle with the apex formed by the distal LBB and the base by the most distal Purkinje potentials. Linear radiofrequency catheter ablation at the base of the triangle was performed, followed by ablation within the virtual triangle sparing the LBB and both fascicles ("de-networking"). All patients were treated without complications. During 1-year follow-up, only 2/10(20%) patients experienced recurrence in form of a single episode of polymorphic VT/VF. CONCLUSION Catheter ablation of VF through "de-networking" of the Purkinje system in patients without overt arrhythmia substrate or trigger appears safe and effective and will require further study in a larger patient cohort.
Collapse
Affiliation(s)
- Guram Imnadze
- Heart and Diabetes Center North Rhine‐WestphaliaClinic of Arrhythmia MagnagementBad OeynhausenNordrhein‐Westfalen, DE
- Ruhr‐Universitat Bochum Medizinische FakultatArrhythmia ManagementBochumNordrhein‐Westfalen, DE
- Department of Arrhythmia ManagementKlinikum OsnabrueckOsnabrueckGermany
| | - Thomas Zerm
- Electrophysiology DepartmentAlbertinen Hospital, Academic Teaching Hospital of the University of Hamburg ‐ EppendorfHamburgGermany
| |
Collapse
|
14
|
Calloe K. Doctoral Dissertation: The transient outward potassium current in healthy and diseased hearts. Acta Physiol (Oxf) 2019; 225 Suppl 717:e13225. [PMID: 30628199 DOI: 10.1111/apha.13225] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2018] [Revised: 11/20/2018] [Accepted: 11/21/2018] [Indexed: 12/13/2022]
Affiliation(s)
- Kirstine Calloe
- Section for Anatomy; Biochemistry and Physiology; Department for Veterinary and Animal Sciences; Faculty of Health and Medical Sciences; University of Copenhagen; Frederiksberg C Denmark
| |
Collapse
|
15
|
Boyden PA. Purkinje physiology and pathophysiology. J Interv Card Electrophysiol 2018; 52:255-262. [PMID: 30056516 DOI: 10.1007/s10840-018-0414-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Accepted: 07/17/2018] [Indexed: 01/08/2023]
Abstract
There has always been an appreciation of the role of Purkinje fibers in the fast conduction of the normal cardiac impulse. Here, we briefly update our knowledge of this important set of cardiac cells. We discuss the anatomy of a Purkinje fiber strand, the importance of longitudinal conduction within a strand, circus movement within a strand, conduction, and excitability properties of Purkinjes. At the cell level, we discuss the important components of the ion channel makeup in the nonremodeled Purkinjes of healthy hearts. Finally, we discuss the role of the Purkinjes in forming the heritable arrhythmogenic substrates such as long QT, heritable conduction slowing, CPVT, sQT, and Brugada syndromes.
Collapse
Affiliation(s)
- Penelope A Boyden
- Department of Pharmacology, Columbia University, New York, NY, 10032, USA.
| |
Collapse
|
16
|
Martinez ME, Walton RD, Bayer JD, Haïssaguerre M, Vigmond EJ, Hocini M, Bernus O. Role of the Purkinje-Muscle Junction on the Ventricular Repolarization Heterogeneity in the Healthy and Ischemic Ovine Ventricular Myocardium. Front Physiol 2018; 9:718. [PMID: 29962961 PMCID: PMC6010581 DOI: 10.3389/fphys.2018.00718] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Accepted: 05/24/2018] [Indexed: 01/23/2023] Open
Abstract
Alteration of action potential duration (APD) heterogeneity contributes to arrhythmogenesis. Purkinje-muscle junctions (PMJs) present differential electrophysiological properties including longer APD. The goal of this study was to determine if Purkinje-related or myocardial focal activation modulates ventricular repolarization differentially in healthy and ischemic myocardium. Simultaneous epicardial (EPI) and endocardial (ENDO) optical mapping was performed on sheep left ventricular (LV) wedges with intact free-running Purkinje network (N = 7). Preparations were paced on either ENDO or EPI surfaces, or the free-running Purkinje fibers (PFs), mimicking normal activation. EPI and ENDO APDs were assessed for each pacing configuration, before and after (7 min) of the onset of no-flow ischemia. Experiments were supported by simulations. In control conditions, maximal APD was found at endocardial PMJ sites. We observed a significant transmural APD gradient for PF pacing with PMJ APD = 347 ± 41 ms and EPI APD = 273 ± 36 ms (p < 0.001). A similar transmural gradient was observed when pacing ENDO (49 ± 31 ms; p = 0.005). However, the gradient was reduced when pacing EPI (37 ± 20 ms; p = 0.005). Global dispersion of repolarization was the most pronounced for EPI pacing. In ischemia, both ENDO and EPI APD were reduced (p = 0.005) and the transmural APD gradient (109 ± 55 ms) was increased when pacing ENDO compared to control condition or when pacing EPI (p < 0.05). APD maxima remained localized at functional PMJs during ischemia. Local repolarization dispersion was significantly higher at the PMJ than at other sites. The results were consistent with simulations. We found that the activation sequence modulates repolarization heterogeneity in the ischemic sheep LV. PMJs remain active following ischemia and exert significant influence on local repolarization patterns.
Collapse
Affiliation(s)
- Marine E Martinez
- Centre de Recherche Cardio-Thoracique de Bordeaux, Université de Bordeaux, Bordeaux, France.,INSERM U1045, Centre de Recherche Cardio-Thoracique de Bordeaux, Bordeaux, France.,IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, Bordeaux, France
| | - Richard D Walton
- Centre de Recherche Cardio-Thoracique de Bordeaux, Université de Bordeaux, Bordeaux, France.,INSERM U1045, Centre de Recherche Cardio-Thoracique de Bordeaux, Bordeaux, France.,IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, Bordeaux, France
| | - Jason D Bayer
- Centre de Recherche Cardio-Thoracique de Bordeaux, Université de Bordeaux, Bordeaux, France.,UMR5251, Centre National De La Recherche Scientifique, Institut de Mathématiques de Bordeaux, Bordeaux, France
| | - Michel Haïssaguerre
- Centre de Recherche Cardio-Thoracique de Bordeaux, Université de Bordeaux, Bordeaux, France.,INSERM U1045, Centre de Recherche Cardio-Thoracique de Bordeaux, Bordeaux, France.,IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, Bordeaux, France.,Centre Hospitalier Universitaire, Bordeaux University Hospital, Hopital Cardiologique du Haut Lévèque, Bordeaux, France
| | - Edward J Vigmond
- Centre de Recherche Cardio-Thoracique de Bordeaux, Université de Bordeaux, Bordeaux, France.,UMR5251, Centre National De La Recherche Scientifique, Institut de Mathématiques de Bordeaux, Bordeaux, France
| | - Mélèze Hocini
- Centre de Recherche Cardio-Thoracique de Bordeaux, Université de Bordeaux, Bordeaux, France.,INSERM U1045, Centre de Recherche Cardio-Thoracique de Bordeaux, Bordeaux, France.,IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, Bordeaux, France.,Centre Hospitalier Universitaire, Bordeaux University Hospital, Hopital Cardiologique du Haut Lévèque, Bordeaux, France
| | - Olivier Bernus
- Centre de Recherche Cardio-Thoracique de Bordeaux, Université de Bordeaux, Bordeaux, France.,INSERM U1045, Centre de Recherche Cardio-Thoracique de Bordeaux, Bordeaux, France.,IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, Bordeaux, France
| |
Collapse
|
17
|
Hou JW, Li W, Guo K, Chen XM, Chen YH, Li CY, Zhao BC, Zhao J, Wang H, Wang YP, Li YG. Antiarrhythmic effects and potential mechanism of WenXin KeLi in cardiac Purkinje cells. Heart Rhythm 2016; 13:973-82. [DOI: 10.1016/j.hrthm.2015.12.023] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Indexed: 10/22/2022]
|
18
|
Maass K, Shekhar A, Lu J, Kang G, See F, Kim EE, Delgado C, Shen S, Cohen L, Fishman GI. Isolation and characterization of embryonic stem cell-derived cardiac Purkinje cells. Stem Cells 2016; 33:1102-12. [PMID: 25524238 DOI: 10.1002/stem.1921] [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] [Received: 08/28/2014] [Revised: 11/18/2014] [Accepted: 11/18/2014] [Indexed: 12/16/2022]
Abstract
The cardiac Purkinje fiber network is composed of highly specialized cardiomyocytes responsible for the synchronous excitation and contraction of the ventricles. Computational modeling, experimental animal studies, and intracardiac electrical recordings from patients with heritable and acquired forms of heart disease suggest that Purkinje cells (PCs) may also serve as critical triggers of life-threatening arrhythmias. Nonetheless, owing to the difficulty in isolating and studying this rare population of cells, the precise role of PC in arrhythmogenesis and the underlying molecular mechanisms responsible for their proarrhythmic behavior are not fully characterized. Conceptually, a stem cell-based model system might facilitate studies of PC-dependent arrhythmia mechanisms and serve as a platform to test novel therapeutics. Here, we describe the generation of murine embryonic stem cells (ESC) harboring pan-cardiomyocyte and PC-specific reporter genes. We demonstrate that the dual reporter gene strategy may be used to identify and isolate the rare ESC-derived PC (ESC-PC) from a mixed population of cardiogenic cells. ESC-PC display transcriptional signatures and functional properties, including action potentials, intracellular calcium cycling, and chronotropic behavior comparable to endogenous PC. Our results suggest that stem-cell derived PC are a feasible new platform for studies of developmental biology, disease pathogenesis, and screening for novel antiarrhythmic therapies.
Collapse
Affiliation(s)
- Karen Maass
- Leon H. Charney Division of Cardiology, New York University School of Medicine, New York, New York, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Boyden PA, Dun W, Robinson RB. Cardiac Purkinje fibers and arrhythmias; The GK Moe Award Lecture 2015. Heart Rhythm 2016; 13:1172-1181. [PMID: 26775142 DOI: 10.1016/j.hrthm.2016.01.011] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Indexed: 02/07/2023]
Abstract
Purkinje fibers/cells continue to be a focus of arrhythmologists. Here we review several new ideas that have emerged in the literature and fold them into important new points. These points include the following: some proteins in Purkinje cells are specific to Purkinjes; pacemaker function in Purkinje may be similar to that of the sinus node cell; sink-source concerns about tracts/sheets of Purkinje fibers; role of Ito in arrhythmias; and genetic lesions in Purkinjes and their high impact on cardiac rhythm. Although new ideas about the remodeled Purkinje cell are not the focus of this review, one can easily imagine how Purkinjes and their function may be altered in diseased hearts.
Collapse
Affiliation(s)
- Penelope A Boyden
- Department of Pharmacology, Center for Molecular Therapeutics, Columbia University, New York, New York
| | - Wen Dun
- Department of Pharmacology, Center for Molecular Therapeutics, Columbia University, New York, New York
| | - Richard B Robinson
- Department of Pharmacology, Center for Molecular Therapeutics, Columbia University, New York, New York
| |
Collapse
|
20
|
|
21
|
Vigmond EJ, Stuyvers BD. Modeling our understanding of the His-Purkinje system. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2015; 120:179-88. [PMID: 26740015 DOI: 10.1016/j.pbiomolbio.2015.12.013] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Revised: 12/18/2015] [Accepted: 12/22/2015] [Indexed: 01/25/2023]
Abstract
The His-Purkinje System (HPS) is responsible for the rapid electric conduction in the ventricles. It relays electrical impulses from the atrioventricular node to the muscle cells and, thus, coordinates the contraction of ventricles in order to ensure proper cardiac pump function. The HPS has been implicated in the genesis of ventricular tachycardia and fibrillation as a source of ectopic beats, as well as forming distinct portions of reentry circuitry. Despite its importance, it remains much less well characterized, structurally and functionally, than the myocardium. Notably, important differences exist with regard to cell structure and electrophysiology, including ion channels, intracellular calcium handling, and gap junctions. Very few computational models address the HPS, and the majority of organ level modeling studies omit it. This review will provide an overview of our current knowledge of structure and function (including electrophysiology) of the HPS. We will review the most recent advances in modeling of the system from the single cell to the organ level, with considerations for relevant interspecies distinctions.
Collapse
Affiliation(s)
- Edward J Vigmond
- LIRYC, Institute of Electrophysiology and Cardiac Modeling, Hôpital Xavier Arnozan, avenue Haut-Lévèque, 33600 Pessac, France; Institut de Mathématiques de Bordeaux, Université de Bordeaux, 351, cours de la Libération, F 33 405 Talence, France; Department of Electrical and Computer Engineering, University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada.
| | - Bruno D Stuyvers
- LIRYC, Institute of Electrophysiology and Cardiac Modeling, Hôpital Xavier Arnozan, avenue Haut-Lévèque, 33600 Pessac, France; Université de Bordeaux, 351, cours de la Libération, F 33 405 Talence, France; Faculty of Medicine, Memorial University of Newfoundland, 300 Prince Phillip Drive, St. John's, NL A1B 3V6, Canada.
| |
Collapse
|
22
|
Latchamsetty R, Bogun F. Premature Ventricular Complexes and Premature Ventricular Complex Induced Cardiomyopathy. Curr Probl Cardiol 2015; 40:379-422. [DOI: 10.1016/j.cpcardiol.2015.03.002] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
23
|
Purkinje Cells as Sources of Arrhythmias in Long QT Syndrome Type 3. Sci Rep 2015; 5:13287. [PMID: 26289036 PMCID: PMC4542521 DOI: 10.1038/srep13287] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Accepted: 07/16/2015] [Indexed: 12/27/2022] Open
Abstract
Long QT syndrome (LQTS) is characterized by ventricular arrhythmias and sudden cardiac death. Purkinje cells (PC) within the specialized cardiac conduction system have unique electrophysiological properties that we hypothesize may produce the primary sources of arrhythmia in heritable LQTS. LQTS type 3 (LQT3) transgenic mice harboring the ΔKPQ+/− mutation were crossed with Contactin2-EGFP BAC transgenic mice, which express a fluorescent reporter gene within the Purkinje fiber network. Isolated ventricular myocytes (VMs) (EGFP−) and PCs (EGFP+) from wild type and ΔKPQ mutant hearts were compared using the whole-cell patch clamp technique and microfluorimetry of calcium transients. Increased late sodium current was seen in ΔKPQ-PCs and ΔKPQ-VMs, with larger density in ΔKPQ-PCs. Marked prolongation of action potential duration of ΔKPQ-PCs was seen compared to ΔKPQ-VMs. ΔKPQ-PCs, but not ΔKPQ-VMs, exhibited frequent early afterdepolarizations, which corresponded to repetitive oscillations of intracellular calcium. Abnormalities in cell repolarization were reversed with exposure to mexiletine. We present the first direct experimental evidence that PCs are uniquely sensitive to LQT3 mutations, displaying electrophysiological behavior that is highly pro-arrhythmic.
Collapse
|
24
|
Meens MJ, Kwak BR, Duffy HS. Role of connexins and pannexins in cardiovascular physiology. Cell Mol Life Sci 2015; 72:2779-92. [PMID: 26091747 PMCID: PMC11113959 DOI: 10.1007/s00018-015-1959-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 06/11/2015] [Indexed: 12/26/2022]
Abstract
Connexins and pannexins form connexons, pannexons and membrane channels, which are critically involved in many aspects of cardiovascular physiology. For that reason, a vast number of studies have addressed the role of connexins and pannexins in the arterial and venous systems as well as in the heart. Moreover, a role for connexins in lymphatics has recently also been suggested. This review provides an overview of the current knowledge regarding the involvement of connexins and pannexins in cardiovascular physiology.
Collapse
Affiliation(s)
- Merlijn J. Meens
- Department of Pathology and Immunology, University of Geneva, Rue Michel-Servet 1, 1211 Geneva 4, Switzerland
- Department of Medical Specializations-Cardiology, University of Geneva, Geneva, Switzerland
| | - Brenda R. Kwak
- Department of Pathology and Immunology, University of Geneva, Rue Michel-Servet 1, 1211 Geneva 4, Switzerland
- Department of Medical Specializations-Cardiology, University of Geneva, Geneva, Switzerland
| | | |
Collapse
|
25
|
Abstract
Optimal cardiac function depends on proper timing of excitation and contraction in various regions of the heart, as well as on appropriate heart rate. This is accomplished via specialized electrical properties of various components of the system, including the sinoatrial node, atria, atrioventricular node, His-Purkinje system, and ventricles. Here we review the major regionally determined electrical properties of these cardiac regions and present the available data regarding the molecular and ionic bases of regional cardiac function and dysfunction. Understanding these differences is of fundamental importance for the investigation of arrhythmia mechanisms and pharmacotherapy.
Collapse
Affiliation(s)
- Daniel C Bartos
- Department of Pharmacology, University of California Davis, Davis, California, USA
| | - Eleonora Grandi
- Department of Pharmacology, University of California Davis, Davis, California, USA
| | - Crystal M Ripplinger
- Department of Pharmacology, University of California Davis, Davis, California, USA
| |
Collapse
|
26
|
Angel N, Li L, Dosdall DJ. His bundle activates faster than ventricular myocardium during prolonged ventricular fibrillation. PLoS One 2014; 9:e101666. [PMID: 25036418 PMCID: PMC4103805 DOI: 10.1371/journal.pone.0101666] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Accepted: 06/09/2014] [Indexed: 11/30/2022] Open
Abstract
Background The Purkinje fiber system has recently been implicated as an important driver of the rapid activation rate during long duration ventricular fibrillation (VF>2 minutes). The goal of this study is to determine whether this activity propagates to or occurs in the proximal specialized conduction system during VF as well. Methods and Results An 8×8 array with 300 µm spaced electrodes was placed over the His bundles of isolated, perfused rabbit hearts (n = 12). Ventricular myocardial (VM) and His activations were differentiated by calculating Laplacian recordings from unipolar signals. Activation rates of the VM and His bundle were compared and the His bundle conduction velocity was measured during perfused VF followed by 8 minutes of unperfused VF. During perfused VF the average VM activation rate of 11.04 activations/sec was significantly higher than the His bundle activation rate of 6.88 activations/sec (p<0.05). However from 3–8 minutes of unperfused VF the His system activation rate (6.16, 5.53, 5.14, 5.22, 6.00, and 4.62 activations/sec significantly faster than the rate of the VM (4.67, 3.63, 2.94, 2.24, 3.45, and 2.31 activations/sec) (p<0.05). The conduction velocity of the His system immediately decreased to 94% of the sinus rate during perfused VF then gradually decreased to 67% of sinus rhythm conduction at 8 minutes of unperfused VF. Conclusion During prolonged VF the activation rate of the His bundle is faster than that of the VM. This suggests that the proximal conduction system, like the distal Purkinje system, may be an important driver during long duration VF and may be a target for interventional therapy.
Collapse
Affiliation(s)
- Nathan Angel
- Comprehensive Arrhythmia Research & Management Center, Division of Cardiovascular Medicine, University of Utah, Salt Lake City, UT, United States of America
- Department of Bioengineering, University of Utah, Salt Lake City, UT, United States of America
| | - Li Li
- Comprehensive Arrhythmia Research & Management Center, Division of Cardiovascular Medicine, University of Utah, Salt Lake City, UT, United States of America
| | - Derek J. Dosdall
- Comprehensive Arrhythmia Research & Management Center, Division of Cardiovascular Medicine, University of Utah, Salt Lake City, UT, United States of America
- Department of Bioengineering, University of Utah, Salt Lake City, UT, United States of America
- Center for Engineering Innovation, University of Utah, Salt Lake City, UT, United States of America
- * E-mail:
| |
Collapse
|
27
|
Iyer V, Sampson KJ, Kass RS. Modeling tissue- and mutation- specific electrophysiological effects in the long QT syndrome: role of the Purkinje fiber. PLoS One 2014; 9:e97720. [PMID: 24892747 PMCID: PMC4043730 DOI: 10.1371/journal.pone.0097720] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Accepted: 03/28/2014] [Indexed: 12/05/2022] Open
Abstract
Congenital long QT syndrome is a heritable family of arrhythmias caused by mutations in 13 genes encoding ion channel complex proteins. Mounting evidence has implicated the Purkinje fiber network in the genesis of ventricular arrhythmias. In this study, we explore the hypothesis that long QT mutations can demonstrate different phenotypes depending on the tissue type of expression. Using computational models of the human ventricular myocyte and the Purkinje fiber cell, the biophysical alteration in channel function in LQT1, LQT2, LQT3, and LQT7 are modeled. We identified that the plateau potential was important in LQT1 and LQT2, in which mutation led to minimal action potential prolongation in Purkinje fiber cells. The phenotype of LQT3 mutation was dependent on the biophysical alteration induced as well as tissue type. The canonical ΔKPQ mutation causes severe action potential prolongation in both tissue types. For LQT3 mutation F1473C, characterized by shifted channel availability, a more severe phenotype was seen in Purkinje fiber cells with action potential prolongation and early afterdepolarizations. The LQT3 mutation S1904L demonstrated striking effects on action potential duration restitution and more severe action potential prolongation in Purkinje fiber cells at higher heart rates. Voltage clamp simulations highlight the mechanism of effect of these mutations in different tissue types, and impact of drug therapy is explored. We conclude that arrhythmia formation in long QT syndrome may depend not only on the basis of mutation and biophysical alteration, but also upon tissue of expression. The Purkinje fiber network may represent an important therapeutic target in the management of patients with heritable channelopathies.
Collapse
Affiliation(s)
- Vivek Iyer
- Department of Pharmacology, College of Physicians and Surgeons of Columbia University, New York, New York, United States of America
- * E-mail:
| | - Kevin J. Sampson
- Department of Pharmacology, College of Physicians and Surgeons of Columbia University, New York, New York, United States of America
| | - Robert S. Kass
- Department of Pharmacology, College of Physicians and Surgeons of Columbia University, New York, New York, United States of America
| |
Collapse
|
28
|
Huang J, Dosdall DJ, Cheng KA, Li L, Rogers JM, Ideker RE. The importance of Purkinje activation in long duration ventricular fibrillation. J Am Heart Assoc 2014; 3:e000495. [PMID: 24584738 PMCID: PMC3959715 DOI: 10.1161/jaha.113.000495] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
BACKGROUND The mechanisms that maintain long duration ventricular fibrillation (LDVF) are unclear. The difference in distribution of the Purkinje system in dogs and pigs was explored to determine if Purkinje activation propagates to stimulate working myocardium (WM) during LDVF and WM pacing. METHODS AND RESULTS In-vivo extracellular recordings were made from 1044 intramural plunge and epicardial plaque electrodes in 6 pig and 6 dog hearts. Sinus activation propagated sequentially from the endocardium to the epicardium in dogs but not pigs. During epicardial pacing, activation propagated along the endocardium and traversed the LV wall almost parallel to the epicardium in dogs, but in pigs propagated away from the pacing site approximately perpendicular to the epicardium. After 1 minute of VF, activation rate near the endocardium was significantly faster than near the epicardium in dogs (P<0.01) but not pigs (P>0.05). From 2 to 10 minutes of LDVF, recordings exhibiting Purkinje activations were near the endocardium in dogs (P<0.01) but were scattered transmurally in pigs, and the WM activation rate in recordings in which Purkinje activations were present was significantly faster than the WM activation rate in recordings in which Purkinje activations were absent (P<0.01). In 10 isolated perfused dog hearts, the LV endocardium was exposed and 2 microelectrodes were inserted into Purkinje and adjacent myocardial cells. After 5 minutes of LDVF, mean Purkinje activation rate was significantly faster than mean WM activation rate (P<0.01). CONCLUSION These extracellular and intracellular findings about activation support the hypothesis that Purkinje activation propagates to stimulate WM during sinus rhythm, pacing, and LDVF.
Collapse
Affiliation(s)
- Jian Huang
- Cardiac Rhythm Management Laboratory, Division of Cardiovascular Disease, Department of Medicine, University of Alabama at Birmingham, AL
| | | | | | | | | | | |
Collapse
|
29
|
Syed FF, Hai JJ, Lachman N, DeSimone CV, Asirvatham SJ. The infrahisian conduction system and endocavitary cardiac structures: relevance for the invasive electrophysiologist. J Interv Card Electrophysiol 2013; 39:45-56. [PMID: 24322419 DOI: 10.1007/s10840-013-9858-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Accepted: 10/24/2013] [Indexed: 01/27/2023]
Affiliation(s)
- Faisal F Syed
- Division of Cardiovascular Diseases, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA
| | | | | | | | | |
Collapse
|
30
|
Abstract
An electrophysiological analysis of canine single ventricular myocardial (VM) and Purkinje (P) cells was carried out by means of whole cell voltage clamp method. The following results in VM versus P cells were obtained. INa3 was present, had a threshold negative to the fast activating-inactivating INa1, its slow inactivation was cut off by INa1, and contributed to Na+ influx at INa1 threshold. INa1 was smaller and had a less negative threshold. There was no comparable slowly inactivating INa2, accounting for the shorter action potential. Slope conductance at resting potential was about double and decreased to a minimum value at the larger and less negative IK1 peak. The negative slope region of I-V relation was smaller during fast ramps and larger during slow ramps than in P cells, occurred in the voltage range of IK1 block by Mg2+, was not affected by a lower Vh and TTX and was eliminated by Ba2+, in contrast to P cells. ICa was larger, peaked at positive potentials and was eliminated by Ni2+. Ito was much smaller, began at more positive values, was abolished by less negative Vh and by 4-aminopyridine, included a sustained current that 4-aminopyridine decreased but did not eliminate. Steeper ramps increased IK1 peak as well as the fall in outward current during repolarization, consistent with a time-dependent block and unblock of IK1 by polyamines. During repolarization, the positive slope region was consistently present and was similar in amplitude to IK1 peak, whereas it was small or altogether missing in P cells. The total outward current at positive potentials comprised a larger IK1 component whereas it included a larger Ito and sustained current in P cells. These and other results provide a better understanding of the mechanisms underlying the action potential of VM and P cells under normal and some abnormal (arrhythmias) conditions.
Collapse
Affiliation(s)
- M Vassalle
- Department of Physiology and Pharmacology, State University of New York, Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, NY 11203, U.S.A
| | | |
Collapse
|
31
|
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.
Collapse
|
32
|
Long DY, Dong JZ, Sang CH, Jiang CX, Tang RB, Yan Q, Yu RH, Li SN, Yao Y, Ning M, Lin T, Salim M, Du X, Ma CS. Isolated Conduction Within the Left His-Purkenje System During Sinus Rhythm and Idiopathic Left Ventricle Tachycardia. Circ Arrhythm Electrophysiol 2013; 6:522-7. [PMID: 23673906 DOI: 10.1161/circep.113.000293] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- De-Yong Long
- From the Cardiology Department, Beijing An Zhen Hospital, Capital Medical University, Beijing, China
| | - Jian-Zeng Dong
- From the Cardiology Department, Beijing An Zhen Hospital, Capital Medical University, Beijing, China
| | - Cai-Hua Sang
- From the Cardiology Department, Beijing An Zhen Hospital, Capital Medical University, Beijing, China
| | - Chen-Xi Jiang
- From the Cardiology Department, Beijing An Zhen Hospital, Capital Medical University, Beijing, China
| | - Ri-Bo Tang
- From the Cardiology Department, Beijing An Zhen Hospital, Capital Medical University, Beijing, China
| | - Qian Yan
- From the Cardiology Department, Beijing An Zhen Hospital, Capital Medical University, Beijing, China
| | - Rong-Hui Yu
- From the Cardiology Department, Beijing An Zhen Hospital, Capital Medical University, Beijing, China
| | - Song-Nan Li
- From the Cardiology Department, Beijing An Zhen Hospital, Capital Medical University, Beijing, China
| | - Yan Yao
- From the Cardiology Department, Beijing An Zhen Hospital, Capital Medical University, Beijing, China
| | - Man Ning
- From the Cardiology Department, Beijing An Zhen Hospital, Capital Medical University, Beijing, China
| | - Tao Lin
- From the Cardiology Department, Beijing An Zhen Hospital, Capital Medical University, Beijing, China
| | - Mohamed Salim
- From the Cardiology Department, Beijing An Zhen Hospital, Capital Medical University, Beijing, China
| | - Xin Du
- From the Cardiology Department, Beijing An Zhen Hospital, Capital Medical University, Beijing, China
| | - Chang-Sheng Ma
- From the Cardiology Department, Beijing An Zhen Hospital, Capital Medical University, Beijing, China
| |
Collapse
|
33
|
Cavanaugh J, French JA. Post-partum variation in the expression of paternal care is unrelated to urinary steroid metabolites in marmoset fathers. Horm Behav 2013; 63:551-8. [PMID: 23439223 PMCID: PMC3746002 DOI: 10.1016/j.yhbeh.2013.02.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Revised: 02/11/2013] [Accepted: 02/12/2013] [Indexed: 11/17/2022]
Abstract
The organization and activation of maternal care are known to be highly regulated by hormones and there is growing evidence that expression of paternal care is also related to endocrine substrates. We examined the relationship between paternal behavior and steroid hormones in marmoset fathers (Callithrix geoffroyi) and evaluated whether hormone-paternal behavior relationships were altered by previous offspring-care experience in males. Based on previous findings, we predicted that testosterone, estradiol, and cortisol would decrease following the birth of offspring and would be lowest during the period of maximal infant carrying. Furthermore, we predicted that post-partum changes in carrying effort and hormone levels would be influenced by the level of offspring-care experience. Carrying effort and other paternal care behaviors underwent temporal changes over the post-partum period, but these patterns were not related to variation in hormone concentrations over the same period. There was a limited effect of offspring-care experience on hormone concentrations, but experience was found to play a role in the expression of paternal care, with experienced fathers engaging in significantly more infant allogrooming than inexperienced fathers. Furthermore, inexperienced fathers increased the frequency of food sharing in response to infant begging across the post-partum period, while experienced fathers displayed consistently low levels. We posit that a combination of experiential factors and an increased role for alloparents in offspring-care led to these changes. However, it appears that hormonal changes may not influence paternal responsiveness in white-faced marmoset fathers and that hormone-paternal behavior relationships are not critically dependent on a male's previous offspring-care experience.
Collapse
Affiliation(s)
- Jon Cavanaugh
- Callitrichid Research Center, Department of Psychology, University of Nebraska, Omaha, NE 68182, USA.
| | | |
Collapse
|
34
|
Cordeiro JM. The Purkinje fiber preparation: 60 years of progress culminating in the mouse preparation. Heart Rhythm 2012; 10:88-9. [PMID: 23085129 DOI: 10.1016/j.hrthm.2012.10.027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Indexed: 12/01/2022]
|
35
|
Vaidyanathan R, O'Connell RP, Deo M, Milstein ML, Furspan P, Herron TJ, Pandit SV, Musa H, Berenfeld O, Jalife J, Anumonwo JMB. The ionic bases of the action potential in isolated mouse cardiac Purkinje cell. Heart Rhythm 2012; 10:80-7. [PMID: 23041576 DOI: 10.1016/j.hrthm.2012.10.002] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Indexed: 02/01/2023]
Abstract
BACKGROUND Collecting electrophysiological and molecular data from the murine conduction system presents technical challenges. Thus, only little advantage has been taken of numerous genetically engineered murine models to study excitation through the cardiac conduction system of the mouse. OBJECTIVE To develop an approach for isolating murine cardiac Purkinje cells (PCs), to characterize major ionic currents and to use the data to simulate action potentials (APs) recorded from PCs. METHODS Light microscopy was used to isolate and identify PCs from apical and septal cells. Current and voltage clamp techniques were used to record APs and whole cell currents. We then simulated a PC AP on the basis of our experimental data. RESULTS APs recorded from PCs were significantly longer than those recorded from ventricular cells. The prominent plateau phase of the PC AP was very negative (≈-40 mV). Spontaneous activity was observed only in PCs. The inward rectifier current demonstrated no significant differences compared to ventricular myocytes (VMs). However, sodium current density was larger, and the voltage-gated potassium current density was significantly less in PCs compared with myocytes. T-type Ca(2+) currents (I(Ca,T)) were present in PCs but not VMs. Computer simulations suggest that I(Ca,T) and cytosolic calcium diffusion significantly modulate AP profile recorded in PCs, as compared to VMs. CONCLUSIONS Our study provides the first comprehensive ionic profile of murine PCs. The data show unique features of PC ionic mechanisms that govern its excitation process. Experimental data and numerical modeling results suggest that a smaller voltage-gated potassium current and the presence of I(Ca,T) are important determinants of the longer and relatively negative plateau phase of the APs.
Collapse
Affiliation(s)
- Ravi Vaidyanathan
- Department of Pharmacology, SUNY Upstate Medical University, Syracuse, New York, USA
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
36
|
Zhao Z, Xie Y, Wen H, Xiao D, Allen C, Fefelova N, Dun W, Boyden PA, Qu Z, Xie LH. Role of the transient outward potassium current in the genesis of early afterdepolarizations in cardiac cells. Cardiovasc Res 2012; 95:308-16. [PMID: 22660482 DOI: 10.1093/cvr/cvs183] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
AIMS The transient outward potassium current (I(to)) plays important roles in action potential (AP) morphology and dynamics; however, its role in the genesis of early afterdepolarizations (EADs) is not well understood. We aimed to study the effects and mechanisms of I(to) on EAD genesis in cardiac cells using combined experimental and computational approaches. METHODS AND RESULTS We first carried out patch-clamp experiments in isolated rabbit ventricular myocytes exposed to H(2)O(2) (0.2 or 1 mM), in which EADs were induced at a slow pacing rate. EADs were eliminated by either increasing the pacing rate or blocking I(to) with 2 mM 4-aminopyridine. In addition to enhancing the L-type calcium current (I(Ca,L)) and the late sodium current, H(2)O(2) also increased the conductance, slowed inactivation, and accelerated recovery from the inactivation of I(to). Computer simulations showed that I(to) promoted EADs under the condition of reduced repolarization reserve, consistent with the experimental observations. However, EADs were only promoted in the intermediate ranges of the I(to) conductance and the inactivation time constant. The underlying mechanism is that I(to) lowers the AP plateau voltage into the range at which the time-dependent potassium current (namely I(Ks)) activation is further slowed and I(Ca,L) is available for reactivation, leading to voltage oscillations to manifest EADs. Further experimental studies in cardiac cells of other species validated the theoretical predictions. CONCLUSION In cardiac cells, I(to), with a proper conductance and inactivation speed, potentiates EADs by setting the AP plateau into the voltage range where I(Ca,L) reactivation is facilitated and I(Ks) activation is slowed.
Collapse
Affiliation(s)
- Zhenghang Zhao
- Department of Pharmacology, School of Medicine, Xi'an Jiaotong University, Xi'an, China
| | | | | | | | | | | | | | | | | | | |
Collapse
|
37
|
Li J, Wang K, Zuo W, Lu W, Zhang H. Construction of 3D Realistic Purkinje System: A Locally Linear Embedding-Based Method. J BIOL SYST 2011. [DOI: 10.1142/s0218339010003664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The geometry of canine ventricle with purkinje system provides the data basis for the simulation and analysis of the mechanisms of ventricular pathophysiology. The acquisition of the geometry of the purkinje system, however, is very challenging, and traditional construction approaches are mainly based on modeling using fractal geometry. In this paper, we propose a novel locally linear embedding (LLE)-based method to construct 3D anatomical purkinje system of the canine left ventricle (LV). First, we collect the 2D purkinje system data in a canine ventricle and extract the endocardial surface of the canine left ventricle from 3D canine ventricle. Then, LLE is used to map the 3D geometry of the endocardial surface to a 2D subspace, and the 2D purkinje system data is further embedded into this 2D subspace. Finally, LLE is adopted to map both the 3D geometry of the endocardial surface and the 2D purkinje system data back to the 3D space. An experiment is designed to verify the effectiveness of the LLE-based construction method. The proposed method approaches is promising in restoring realistic purkinje system of the left canine ventricle.
Collapse
Affiliation(s)
- Jie Li
- School of Computer Science and Technology, Harbin Institute of Technology, Harbin, Heilongjiang, China
| | - Kuanquan Wang
- School of Computer Science and Technology, Harbin Institute of Technology, Harbin, Heilongjiang, China
| | - Wangmeng Zuo
- School of Computer Science and Technology, Harbin Institute of Technology, Harbin, Heilongjiang, China
| | - Weigang Lu
- School of Computer Science and Technology, Harbin Institute of Technology, Harbin, Heilongjiang, China
| | - Henggui Zhang
- School of Physics and Astronomy, The University of Manchester, Manchester, UK
| |
Collapse
|
38
|
Atkinson A, Inada S, Li J, Tellez JO, Yanni J, Sleiman R, Allah EA, Anderson RH, Zhang H, Boyett MR, Dobrzynski H. Anatomical and molecular mapping of the left and right ventricular His–Purkinje conduction networks. J Mol Cell Cardiol 2011; 51:689-701. [DOI: 10.1016/j.yjmcc.2011.05.020] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2010] [Revised: 05/23/2011] [Accepted: 05/25/2011] [Indexed: 12/12/2022]
|
39
|
Li P, Rudy Y. A model of canine purkinje cell electrophysiology and Ca(2+) cycling: rate dependence, triggered activity, and comparison to ventricular myocytes. Circ Res 2011; 109:71-9. [PMID: 21566216 DOI: 10.1161/circresaha.111.246512] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Purkinje cells (Pcell) are characterized by different electrophysiological properties and Ca(2+) cycling processes than ventricular myocytes (Vcell) and are frequently involved in ventricular arrhythmias. Yet, the mechanistic basis for their arrhythmic vulnerability is not completely understood. The objectives were to: (1) characterize Pcell electrophysiology, Ca(2+) cycling, and their rate dependence; (2) investigate mechanisms underlying Pcell arrhythmogenicity; and compare Pcell and Vcell electrophysiology, Ca(2+) cycling, and arrhythmic properties. We developed a new mathematical model of Pcell. The Ca(2+) subsystem includes spatial organization and receptors distribution unique to Pcell. Results were: (1) in Pcell and Vcell, Na(+) accumulation via its augmentation of repolarizing I(NaK) dominates action potential duration adaptation and, in Pcell, I(NaL) contributes additional action potential duration shortening at short cycle length; (2) steep Pcell restitution is attributable to slow recovery of I(NaL); (3) biphasic Ca(2+) transients of Pcell reflect the delay between Ca(2+) release from junctional sarcoplasmic reticulum and corbular sarcoplasmic reticulum; (4) Pcell Ca(2+) alternans, unlike Vcell, can develop without inducing action potential alternans; (5) Pcell action potential alternans develops at a shorter cycle length than Vcell, with increased subcellular heterogeneity of Ca(2+) cycling attributable to refractoriness of Ca(2+) release from corbular sarcoplasmic reticulum and junctional sarcoplasmic reticulum; (6) greater Pcell vulnerability to delayed afterdepolarizations is attributable to higher sarcoplasmic reticulum Ca(2+) content and ionic currents that reduce excitation threshold and promote triggered activity; and (7) early after depolarizations generation in Pcell is mostly attributable to reactivation of I(NaL2), whereas I(CaL) plays this role in Vcell. Steeper rate dependence of action potential and Ca(2+) transients, central peripheral heterogeneity of Ca(2+) cycling, and distinct ion channel profile underlie greater arrhythmic vulnerability of Pcell compared to Vcell.
Collapse
Affiliation(s)
- Pan Li
- Department of Biomedical Engineering and Cardiac Bioelectricity and Arrhythmia Center, Campus Box 1097, Washington University in St. Louis, 1 Brookings Drive, St. Louis, MO 63112, USA
| | | |
Collapse
|
40
|
|
41
|
Lee YS, Dun W, Boyden PA, Sobie EA. Complex and rate-dependent beat-to-beat variations in Ca2+ transients of canine Purkinje cells. J Mol Cell Cardiol 2011; 50:662-9. [PMID: 21232541 DOI: 10.1016/j.yjmcc.2010.12.023] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2010] [Revised: 12/09/2010] [Accepted: 12/31/2010] [Indexed: 11/29/2022]
Abstract
Purkinje fibers play an essential role in transmitting electrical impulses through the heart, but they may also serve as triggers for arrhythmias linked to defective intracellular calcium (Ca(2+)) regulation. Although prior studies have extensively characterized spontaneous Ca(2+) release in nondriven Purkinje cells, little attention has been paid to rate-dependent changes in Ca(2+) transients. Therefore we explored the behaviors of Ca(2+) transients at pacing rates ranging from 0.125 to 3 Hz in single canine Purkinje cells loaded with fluo3 and imaged with a confocal microscope. The experiments uncovered the following novel aspects of Ca(2+) regulation in Purkinje cells: 1) the cells exhibit a negative Ca(2+)-frequency relationship (at 2.5 Hz, Ca(2+) transient amplitude was 66 ± 6% smaller than that at 0.125 Hz); 2) sarcoplasmic reticulum (SR) Ca(2+) release occurs as a propagating wave at very low rates but is localized near the cell membrane at higher rates; 3) SR Ca(2+) load declines modestly (10 ± 5%) with an increase in pacing rate from 0.125 Hz to 2.5 Hz; 4) Ca(2+) transients show considerable beat-to-beat variability, with greater variability occurring at higher pacing rates. Analysis of beat-to-beat variability suggests that it can be accounted for by stochastic triggering of local Ca(2+) release events. Consistent with this hypothesis, an increase in triggering probability caused a decrease in the relative variability. These results offer new insight into how Ca(2+) release is normally regulated in Purkinje cells and provide clues regarding how disruptions in this regulation may lead to deleterious consequences such as arrhythmias.
Collapse
Affiliation(s)
- Young-Seon Lee
- Department of Pharmacology and Systems Therapeutics, Mount Sinai School of Medicine, New York, NY, USA
| | | | | | | |
Collapse
|
42
|
Corrias A, Rodriguez B. A novel biophysically-detailed mathematical model of rabbit Purkinje cell electrophysiology. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2010; 2010:2658-61. [PMID: 21096192 DOI: 10.1109/iembs.2010.5626614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Purkinje fibres play an important role in cardiac conduction and have been implicated in arrhythmia in presence of diseased states, genetic mutations, or adverse side effects of drugs. For these reasons, the Purkinje assay is commonly used in pre-clinical in vitro drug assessment of arrhythmic risk. Several investigators have pointed out that rabbit Purkinje cells, compared to other species, have a better sensitivity in detecting arrhythmic risk.
Collapse
Affiliation(s)
- Alberto Corrias
- Computing Laboratory, University of Oxford, Parks Road, OX13QD. United Kingdom.
| | | |
Collapse
|
43
|
Haugaa KH, Amlie JP, Berge KE, Leren TP, Smiseth OA, Edvardsen T. Transmural differences in myocardial contraction in long-QT syndrome: mechanical consequences of ion channel dysfunction. Circulation 2010; 122:1355-63. [PMID: 20855658 DOI: 10.1161/circulationaha.110.960377] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
BACKGROUND Long-QT syndrome (LQTS) is characterized by prolonged myocardial action potential duration. The longest action potential duration is reported in the endomyocardium and midmyocardium. Prolonged action potential duration in LQTS may cause prolonged cardiac contraction, which can be assessed by strain echocardiography. We hypothesized that myocardial contraction is most prolonged in subendocardial myofibers in LQTS patients and that inhomogeneous transmural contraction is related to the risk of spontaneous arrhythmia. METHODS AND RESULTS We included 101 genotyped LQTS mutation carriers and 35 healthy individuals. A history of cardiac arrhythmias was present in 48 mutations carriers, and 53 were asymptomatic. Myocardial contraction duration was assessed by strain echocardiography as time from the ECG Q wave to peak strain in 16 LV segments. Strain was assessed along the longitudinal axis, predominantly representing subendocardial fibers, and along the circumferential axis, representing midmyocardial fibers. Mean contraction duration was longer in LQTS mutation carriers compared with healthy individuals (445 ± 45 versus 390 ± 40 milliseconds; P<0.001) and longer in symptomatic compared with asymptomatic LQTS mutation carriers (460 ± 40 versus 425 ± 45 milliseconds; P<0.001). Contraction duration by longitudinal strain was longer than by circumferential strain in symptomatic LQTS patients (460 ± 45 versus 445±45 milliseconds; P=0.008) but not in asymptomatic patients and healthy individuals, indicating transmural mechanical dispersion. This time difference was present in a majority of LV segments and was most evident in patients with LQT2 and the Jervell and Lange-Nielsen syndrome. CONCLUSION Contraction duration in symptomatic LQTS mutation carriers was longer in the subendocardium than in the midmyocardium, indicating transmural mechanical dispersion, which was not present in asymptomatic and healthy individuals.
Collapse
|
44
|
LaJeunesse DR, Johnson B, Presnell JS, Catignas KK, Zapotoczny G. Peristalsis in the junction region of the Drosophila larval midgut is modulated by DH31 expressing enteroendocrine cells. BMC PHYSIOLOGY 2010; 10:14. [PMID: 20698983 PMCID: PMC2933646 DOI: 10.1186/1472-6793-10-14] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/24/2010] [Accepted: 08/10/2010] [Indexed: 11/24/2022]
Abstract
Background The underlying cellular and molecular mechanisms that coordinate the physiological processes in digestion are complex, cryptic, and involve the integration of multiple cellular and organ systems. In all intestines, peristaltic action of the gut moves food through the various stages of digestion from the anterior end towards the posterior, with the rate of flow dependent on signals, both intrinsic and extrinsic to the gut itself. Results We have identified an enteroendocrine cell type that regulates gut motility in the Drosophila melanogaster larval midgut. These cells are located at the junction of the anterior and the acidic portions of the midgut and are a group of enteroendocrine cells that express the peptide hormone Diuretic Hormone 31 in this region of the gut. Using cell ablation and ectopic activation via expression of the Chlamydomonas reinhardtii blue light-activated channelopsin, we demonstrate that these enteroendocrine cells are both necessary and sufficient for the peristalsis in the junction region of the midgut and require the Diuretic Hormone 31 to affect normal peristalsis in this region. Within the same junction region of the midgut, we have also identified morphological features suggesting that this region acts as a valve that regulates the transit of food from the anterior midgut into the acidic portion of the gut. Conclusions We have characterized and described a set of enteroendocrine cells called the Midgut Junction DH31 expressing cells that are required for peristaltic movement in the junction region between the anterior portion and acidic region of the larval midgut of Drosophila melanogaster. We have shown that the Midgut Junction DH31 expressing cells are necessary and sufficient for motility and that the peptide hormone DH31 is required for peristalsis in the junction region of the midgut. The Drosophila model system will allow for a further dissection of the digestion process and provide a better understanding of the mechanisms that regulate digestion in all organisms.
Collapse
Affiliation(s)
- Dennis R LaJeunesse
- Department of Biology, 312 Eberhart Bldg,, University of North Carolina Greensboro, Greensboro, North Carolina 27402, USA.
| | | | | | | | | |
Collapse
|
45
|
Amin AS, Asghari-Roodsari A, Tan HL. Cardiac sodium channelopathies. Pflugers Arch 2010; 460:223-37. [PMID: 20091048 PMCID: PMC2883928 DOI: 10.1007/s00424-009-0761-0] [Citation(s) in RCA: 144] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2009] [Revised: 11/09/2009] [Accepted: 11/11/2009] [Indexed: 02/06/2023]
Abstract
Cardiac sodium channel are protein complexes that are expressed in the sarcolemma of cardiomyocytes to carry a large inward depolarizing current (INa) during phase 0 of the cardiac action potential. The importance of INa for normal cardiac electrical activity is reflected by the high incidence of arrhythmias in cardiac sodium channelopathies, i.e., arrhythmogenic diseases in patients with mutations in SCN5A, the gene responsible for the pore-forming ion-conducting alpha-subunit, or in genes that encode the ancillary beta-subunits or regulatory proteins of the cardiac sodium channel. While clinical and genetic studies have laid the foundation for our understanding of cardiac sodium channelopathies by establishing links between arrhythmogenic diseases and mutations in genes that encode various subunits of the cardiac sodium channel, biophysical studies (particularly in heterologous expression systems and transgenic mouse models) have provided insights into the mechanisms by which INa dysfunction causes disease in such channelopathies. It is now recognized that mutations that increase INa delay cardiac repolarization, prolong action potential duration, and cause long QT syndrome, while mutations that reduce INa decrease cardiac excitability, reduce electrical conduction velocity, and induce Brugada syndrome, progressive cardiac conduction disease, sick sinus syndrome, or combinations thereof. Recently, mutation-induced INa dysfunction was also linked to dilated cardiomyopathy, atrial fibrillation, and sudden infant death syndrome. This review describes the structure and function of the cardiac sodium channel and its various subunits, summarizes major cardiac sodium channelopathies and the current knowledge concerning their genetic background and underlying molecular mechanisms, and discusses recent advances in the discovery of mutation-specific therapies in the management of these channelopathies.
Collapse
Affiliation(s)
- Ahmad S. Amin
- Heart Failure Research Center, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - Alaleh Asghari-Roodsari
- Heart Failure Research Center, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - Hanno L. Tan
- Department of Cardiology, Heart Failure Research Center, Academic Medical Center, University of Amsterdam, Room K2-109, Meibergdreef 9, Amsterdam, 1105 AZ the Netherlands
| |
Collapse
|
46
|
Sampson KJ, Iyer V, Marks AR, Kass RS. A computational model of Purkinje fibre single cell electrophysiology: implications for the long QT syndrome. J Physiol 2010; 588:2643-55. [PMID: 20498233 DOI: 10.1113/jphysiol.2010.187328] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Computer modelling has emerged as a particularly useful tool in understanding the physiology and pathophysiology of cardiac tissues. Models of ventricular, atrial and nodal tissue have evolved and include detailed ion channel kinetics and intercellular Ca(2+) handling. Purkinje fibre cells play a central role in the electrophysiology of the heart and in the genesis of cardiac arrhythmias. In this study, a new computational model has been constructed that incorporates the major membrane currents that have been isolated in recent experiments using Purkinje fibre cells. The model, which integrates mathematical models of human ion channels based on detailed biophysical studies of their kinetic and voltage-dependent properties, recapitulates distinct electrophysiological characteristics unique to Purkinje fibre cells compared to neighbouring ventricular myocytes. These characteristics include automaticity, hyperpolarized voltage range of the action potential plateau potential, and prolonged action potential duration. Simulations of selective ion channel blockade reproduce responses to pharmacological challenges characteristic of isolated Purkinje fibres in vitro, and importantly, the model predicts that Purkinje fibre cells are prone to severe arrhythmogenic activity in patients harbouring long QT syndrome 3 but much less so for other common forms of long QT. This new Purkinje cellular model can be a useful tool to study tissue-specific drug interactions and the effects of disease-related ion channel dysfunction on the cardiac conduction system.
Collapse
Affiliation(s)
- K J Sampson
- Department of Pharmacology, College of Physicians and Surgeons of Columbia University, New York, NY 10032, USA
| | | | | | | |
Collapse
|
47
|
Abstract
Purkinje cells are specialized for rapid propagation in the heart. Furthermore, Purkinje fibers as the source as well as the perpetuator of arrhythmias is a familiar finding. This is not surprising considering their location in the heart and their unique cell ultrastructure, cell electrophysiology, and mode of excitation-contraction coupling. This review touches on each of these points as we outline what is known today about Purkinje fibers/cells.
Collapse
|
48
|
|
49
|
Stewart P, Aslanidi OV, Noble D, Noble PJ, Boyett MR, Zhang H. Mathematical models of the electrical action potential of Purkinje fibre cells. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2009; 367:2225-2255. [PMID: 19414454 DOI: 10.1098/rsta.2008.0283] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Early development of ionic models for cardiac myocytes, from the pioneering modification of the Hodgkin-Huxley giant squid axon model by Noble to the iconic DiFrancesco-Noble model integrating voltage-gated ionic currents, ion pumps and exchangers, Ca(2+) sequestration and Ca(2+)-induced Ca(2+) release, provided a general description for a mammalian Purkinje fibre (PF) and the framework for modern cardiac models. In the past two decades, development has focused on tissue-specific models with an emphasis on the sino-atrial (SA) node, atria and ventricles, while the PFs have largely been neglected. However, achieving the ultimate goal of creating a virtual human heart will require detailed models of all distinctive regions of the cardiac conduction system, including the PFs, which play an important role in conducting cardiac excitation and ensuring the synchronized timing and sequencing of ventricular contraction. In this paper, we present details of our newly developed model for the human PF cell including validation against experimental data. Ionic mechanisms underlying the heterogeneity between the PF and ventricular action potentials in humans and other species are analysed. The newly developed PF cell model adds a new member to the family of human cardiac cell models developed previously for the SA node, atrial and ventricular cells, which can be incorporated into an anatomical model of the human heart with details of its electrophysiological heterogeneity and anatomical complexity.
Collapse
Affiliation(s)
- Philip Stewart
- School of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK
| | | | | | | | | | | |
Collapse
|
50
|
Maguy A, Le Bouter S, Comtois P, Chartier D, Villeneuve L, Wakili R, Nishida K, Nattel S. Ion channel subunit expression changes in cardiac Purkinje fibers: a potential role in conduction abnormalities associated with congestive heart failure. Circ Res 2009; 104:1113-22. [PMID: 19359601 DOI: 10.1161/circresaha.108.191809] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Purkinje fibers (PFs) play key roles in cardiac conduction and arrhythmogenesis. Congestive heart failure (CHF) causes well-characterized atrial and ventricular ion channel subunit expression changes, but effects on PF ion channel subunits are unknown. This study assessed changes in PF ion channel subunit expression (real-time PCR, immunoblot, immunohistochemistry), action potential properties, and conduction in dogs with ventricular tachypacing-induced CHF. CHF downregulated mRNA expression of subunits involved in action potential propagation (Nav1.5, by 56%; connexin [Cx]40, 66%; Cx43, 56%) and repolarization (Kv4.3, 43%, Kv3.4, 46%). No significant changes occurred in KChIP2, KvLQT1, ERG, or Kir3.1/3.4 mRNA. At the protein level, downregulation was seen for Nav1.5 (by 38%), Kv4.3 (42%), Kv3.4 (57%), Kir2.1 (26%), Cx40 (53%), and Cx43 (30%). Cx43 dephosphorylation was indicated by decreased larger molecular mass bands (pan-Cx43 antibody) and a 57% decrease in Ser368-phosphorylated Cx43 (phospho-specific antibody). Immunohistochemistry revealed reduced Cx40, Cx43, and phospho-Cx43 expression at intercalated disks. Action potential changes were consistent with observed decreases in ion channel subunits: CHF decreased phase 1 slope (by 56%), overshoot (by 32%), and phase 0 dV/dt(max) (by 35%). Impulse propagation was slowed in PF false tendons: conduction velocity decreased significantly from 2.2+/-0.1 m/s (control) to 1.5+/-0.1 m/s (CHF). His-Purkinje conduction also slowed in vivo, with HV interval increasing from 35.5+/-1.2 (control) to 49.3+/-3.4 ms (CHF). These results indicate important effects of CHF on PF ion channel subunit expression. Alterations in subunits governing conduction properties may be particularly important, because CHF-induced impairments in Purkinje tissue conduction, which this study is the first to describe, could contribute significantly to dyssynchronous ventricular activation, a major determinant of prognosis in CHF-patients.
Collapse
Affiliation(s)
- Ange Maguy
- Department of Medicine, Montreal Heart Institute and Université de Montréal, Quebec, Canada
| | | | | | | | | | | | | | | |
Collapse
|