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Marchal GA, Rivaud MR, Wolswinkel R, Basso C, van Veen TAB, Bezzina CR, Remme CA. Genetic background determines the severity of age-dependent cardiac structural abnormalities and arrhythmia susceptibility in Scn5a-1798insD mice. Europace 2024; 26:euae153. [PMID: 38875491 PMCID: PMC11203918 DOI: 10.1093/europace/euae153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Accepted: 05/12/2024] [Indexed: 06/16/2024] Open
Abstract
AIMS Patients with mutations in SCN5A encoding NaV1.5 often display variable severity of electrical and structural alterations, but the underlying mechanisms are not fully elucidated. We here investigate the combined modulatory effect of genetic background and age on disease severity in the Scn5a1798insD/+ mouse model. METHODS AND RESULTS In vivo electrocardiogram and echocardiograms, ex vivo electrical and optical mapping, and histological analyses were performed in adult (2-7 months) and aged (8-28 months) wild-type (WT) and Scn5a1798insD/+ (mutant, MUT) mice from the FVB/N and 129P2 inbred strains. Atrio-ventricular (AV) conduction, ventricular conduction, and ventricular repolarization are modulated by strain, genotype, and age. An aging effect was present in MUT mice, with aged MUT mice of both strains showing prolonged QRS interval and right ventricular (RV) conduction slowing. 129P2-MUT mice were severely affected, with adult and aged 129P2-MUT mice displaying AV and ventricular conduction slowing, prolonged repolarization, and spontaneous arrhythmias. In addition, the 129P2 strain appeared particularly susceptible to age-dependent electrical, functional, and structural alterations including RV conduction slowing, reduced left ventricular (LV) ejection fraction, RV dilatation, and myocardial fibrosis as compared to FVB/N mice. Overall, aged 129P2-MUT mice displayed the most severe conduction defects, RV dilatation, and myocardial fibrosis, in addition to the highest frequency of spontaneous arrhythmia and inducible arrhythmias. CONCLUSION Genetic background and age both modulate disease severity in Scn5a1798insD/+ mice and hence may explain, at least in part, the variable disease expressivity observed in patients with SCN5A mutations. Age- and genetic background-dependent development of cardiac structural alterations furthermore impacts arrhythmia risk. Our findings therefore emphasize the importance of continued assessment of cardiac structure and function in patients carrying SCN5A mutations.
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Affiliation(s)
- Gerard A Marchal
- Department of Experimental Cardiology, Heart Centre, Amsterdam UMC location University of Amsterdam, Meibergdreef 15, PO Box 22660, 1100 DD Amsterdam, The Netherlands
- Amsterdam Cardiovascular Sciences, Heart Failure & Arrhythmias, Meibergdreef 15, PO Box 22660, 1100 DD Amsterdam, The Netherlands
- OptoCARD Lab, Institute of Clinical Physiology (IFC-CNR), Florence, Italy
| | - Mathilde R Rivaud
- Department of Experimental Cardiology, Heart Centre, Amsterdam UMC location University of Amsterdam, Meibergdreef 15, PO Box 22660, 1100 DD Amsterdam, The Netherlands
- Amsterdam Cardiovascular Sciences, Heart Failure & Arrhythmias, Meibergdreef 15, PO Box 22660, 1100 DD Amsterdam, The Netherlands
| | - Rianne Wolswinkel
- Department of Experimental Cardiology, Heart Centre, Amsterdam UMC location University of Amsterdam, Meibergdreef 15, PO Box 22660, 1100 DD Amsterdam, The Netherlands
- Amsterdam Cardiovascular Sciences, Heart Failure & Arrhythmias, Meibergdreef 15, PO Box 22660, 1100 DD Amsterdam, The Netherlands
| | - Cristina Basso
- Department of Cardiac, Thoracic and Vascular Sciences and Public Health, University of Padova, Padua, Italy
| | - Toon A B van Veen
- Department of Medical Physiology, Division Heart & Lungs, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Connie R Bezzina
- Department of Experimental Cardiology, Heart Centre, Amsterdam UMC location University of Amsterdam, Meibergdreef 15, PO Box 22660, 1100 DD Amsterdam, The Netherlands
- Amsterdam Cardiovascular Sciences, Heart Failure & Arrhythmias, Meibergdreef 15, PO Box 22660, 1100 DD Amsterdam, The Netherlands
| | - Carol Ann Remme
- Department of Experimental Cardiology, Heart Centre, Amsterdam UMC location University of Amsterdam, Meibergdreef 15, PO Box 22660, 1100 DD Amsterdam, The Netherlands
- Amsterdam Cardiovascular Sciences, Heart Failure & Arrhythmias, Meibergdreef 15, PO Box 22660, 1100 DD Amsterdam, The Netherlands
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2
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Kappadan V, Sohi A, Parlitz U, Luther S, Uzelac I, Fenton F, Peters NS, Christoph J, Ng FS. Optical mapping of contracting hearts. J Physiol 2023; 601:1353-1370. [PMID: 36866700 PMCID: PMC10952556 DOI: 10.1113/jp283683] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Accepted: 02/27/2023] [Indexed: 03/04/2023] Open
Abstract
Optical mapping is a widely used tool to record and visualize the electrophysiological properties in a variety of myocardial preparations such as Langendorff-perfused isolated hearts, coronary-perfused wedge preparations, and cell culture monolayers. Motion artifact originating from the mechanical contraction of the myocardium creates a significant challenge to performing optical mapping of contracting hearts. Hence, to minimize the motion artifact, cardiac optical mapping studies are mostly performed on non-contracting hearts, where the mechanical contraction is removed using pharmacological excitation-contraction uncouplers. However, such experimental preparations eliminate the possibility of electromechanical interaction, and effects such as mechano-electric feedback cannot be studied. Recent developments in computer vision algorithms and ratiometric techniques have opened the possibility of performing optical mapping studies on isolated contracting hearts. In this review, we discuss the existing techniques and challenges of optical mapping of contracting hearts.
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Affiliation(s)
- Vineesh Kappadan
- National Heart and Lung Institute (NHLI)Imperial College LondonLondonUK
| | - Anies Sohi
- National Heart and Lung Institute (NHLI)Imperial College LondonLondonUK
| | - Ulrich Parlitz
- Biomedical Physcis GroupMax Planck Institute for Dynamics and Self‐OrganizationGöttingenGermany
| | - Stefan Luther
- Biomedical Physcis GroupMax Planck Institute for Dynamics and Self‐OrganizationGöttingenGermany
| | - Ilija Uzelac
- School of PhysicsGeorgia Institute of TechnologyAtlantaGAUSA
| | - Flavio Fenton
- School of PhysicsGeorgia Institute of TechnologyAtlantaGAUSA
| | - Nicholas S Peters
- National Heart and Lung Institute (NHLI)Imperial College LondonLondonUK
| | - Jan Christoph
- Cardiovascular Research InstituteUniversity of CaliforniaSan FranciscoCAUSA
| | - Fu Siong Ng
- National Heart and Lung Institute (NHLI)Imperial College LondonLondonUK
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3
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O'Shea C, Winter J, Kabir SN, O'Reilly M, Wells SP, Baines O, Sommerfeld LC, Correia J, Lei M, Kirchhof P, Holmes AP, Fabritz L, Rajpoot K, Pavlovic D. High resolution optical mapping of cardiac electrophysiology in pre-clinical models. Sci Data 2022; 9:135. [PMID: 35361792 PMCID: PMC8971487 DOI: 10.1038/s41597-022-01253-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 03/07/2022] [Indexed: 11/08/2022] Open
Abstract
Optical mapping of animal models is a widely used technique in pre-clinical cardiac research. It has several advantages over other methods, including higher spatial resolution, contactless recording and direct visualisation of action potentials and calcium transients. Optical mapping enables simultaneous study of action potential and calcium transient morphology, conduction dynamics, regional heterogeneity, restitution and arrhythmogenesis. In this dataset, we have optically mapped Langendorff perfused isolated whole hearts (mouse and guinea pig) and superfused isolated atria (mouse). Raw datasets (consisting of over 400 files) can be combined with open-source software for processing and analysis. We have generated a comprehensive post-processed dataset characterising the baseline cardiac electrophysiology in these widely used pre-clinical models. This dataset also provides reference information detailing the effect of heart rate, clinically used anti-arrhythmic drugs, ischaemia-reperfusion and sympathetic nervous stimulation on cardiac electrophysiology. The effects of these interventions can be studied in a global or regional manner, enabling new insights into the prevention and initiation of arrhythmia.
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Affiliation(s)
- Christopher O'Shea
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK.
| | - James Winter
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK
| | - S Nashitha Kabir
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK
| | - Molly O'Reilly
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK
- Heart Center, Department of Clinical and Experimental Cardiology, Amsterdam UMC, location AMC, Amsterdam, The Netherlands
| | - Simon P Wells
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK
- William Harvey Research Institute, Queen Mary University of London, London, UK
| | - Olivia Baines
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK
| | - Laura C Sommerfeld
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK
- University Center of Cardiovascular Science, UKE, Hamburg, Germany
| | - Joao Correia
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK
| | - Ming Lei
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Paulus Kirchhof
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK
- Department of Cardiology, University Heart and Vascular Centre, University Medical Center Hamburg-Eppendorf, Germany and German Center for Cardiovascular Research (DZHK) partner site Hamburg/Kiel/Lubeck, Lubeck, Germany
- University Center of Cardiovascular Science, UKE, Hamburg, Germany
| | - Andrew P Holmes
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK
- Institute of Clinical Sciences, University of Birmingham, Birmingham, UK
| | - Larissa Fabritz
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK
- Department of Cardiology, University Heart and Vascular Centre, University Medical Center Hamburg-Eppendorf, Germany and German Center for Cardiovascular Research (DZHK) partner site Hamburg/Kiel/Lubeck, Lubeck, Germany
- University Center of Cardiovascular Science, UKE, Hamburg, Germany
| | - Kashif Rajpoot
- School of Computer Science, University of Birmingham, Birmingham, UK
| | - Davor Pavlovic
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK
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4
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Ultrafast four-dimensional imaging of cardiac mechanical wave propagation with sparse optoacoustic sensing. Proc Natl Acad Sci U S A 2021; 118:2103979118. [PMID: 34732573 DOI: 10.1073/pnas.2103979118] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/21/2021] [Indexed: 12/25/2022] Open
Abstract
Propagation of electromechanical waves in excitable heart muscles follows complex spatiotemporal patterns holding the key to understanding life-threatening arrhythmias and other cardiac conditions. Accurate volumetric mapping of cardiac wave propagation is currently hampered by fast heart motion, particularly in small model organisms. Here we demonstrate that ultrafast four-dimensional imaging of cardiac mechanical wave propagation in entire beating murine heart can be accomplished by sparse optoacoustic sensing with high contrast, ∼115-µm spatial and submillisecond temporal resolution. We extract accurate dispersion and phase velocity maps of the cardiac waves and reveal vortex-like patterns associated with mechanical phase singularities that occur during arrhythmic events induced via burst ventricular electric stimulation. The newly introduced cardiac mapping approach is a bold step toward deciphering the complex mechanisms underlying cardiac arrhythmias and enabling precise therapeutic interventions.
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5
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Ronzhina M, Stracina T, Lacinova L, Ondacova K, Pavlovicova M, Marsanova L, Smisek R, Janousek O, Fialova K, Kolarova J, Novakova M, Provaznik I. Di-4-ANEPPS Modulates Electrical Activity and Progress of Myocardial Ischemia in Rabbit Isolated Heart. Front Physiol 2021; 12:667065. [PMID: 34177617 PMCID: PMC8222999 DOI: 10.3389/fphys.2021.667065] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 04/12/2021] [Indexed: 11/16/2022] Open
Abstract
Aims Although voltage-sensitive dye di-4-ANEPPS is a common tool for mapping cardiac electrical activity, reported effects on electrophysiological parameters are rather. The main goals of the study were to reveal effects of the dye on rabbit isolated heart and to verify, whether rabbit isolated heart stained with di-4-ANEPPS is a suitable tool for myocardial ischemia investigation. Methods and Results Study involved experiments on stained (n = 9) and non-stained (n = 11) Langendorff perfused rabbit isolated hearts. Electrophysiological effects of the dye were evaluated by analysis of various electrogram (EG) parameters using common paired and unpaired statistical tests. It was shown that staining the hearts with di-4-ANEPPS leads to only short-term sporadic prolongation of impulse conduction through atria and atrioventricular node. On the other hand, significant irreversible slowing of heart rate and ventricular conduction were found in stained hearts as compared to controls. In patch clamp experiments, significant inhibition of sodium current density was observed in differentiated NG108-15 cells stained by the dye. Although no significant differences in mean number of ventricular premature beats were found between the stained and the non-stained hearts in ischemia as well as in reperfusion, all abovementioned results indicate increased arrhythmogenicity. In isolated hearts during ischemia, prominent ischemic patterns appeared in the stained hearts with 3–4 min delay as compared to the non-stained ones. Moreover, the ischemic changes did not achieve the same magnitude as in controls even after 10 min of ischemia. It resulted in poor performance of ischemia detection by proposed EG parameters, as was quantified by receiver operating characteristics analysis. Conclusion Our results demonstrate significant direct irreversible effect of di-4-ANEPPS on spontaneous heart rate and ventricular impulse conduction in rabbit isolated heart model. Particularly, this should be considered when di-4-ANEPPS is used in ischemia studies in rabbit. Delayed attenuated response of such hearts to ischemia might lead to misinterpretation of obtained results.
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Affiliation(s)
- Marina Ronzhina
- Department of Biomedical Engineering, Faculty of Electrical Engineering and Communication, Brno University of Technology, Brno, Czechia
| | - Tibor Stracina
- Department of Physiology, Faculty of Medicine, Masaryk University, Brno, Czechia
| | - Lubica Lacinova
- Centre of Biosciences, Institute of Molecular Physiology and Genetics, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Katarina Ondacova
- Centre of Biosciences, Institute of Molecular Physiology and Genetics, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Michaela Pavlovicova
- Centre of Biosciences, Institute of Molecular Physiology and Genetics, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Lucie Marsanova
- Department of Biomedical Engineering, Faculty of Electrical Engineering and Communication, Brno University of Technology, Brno, Czechia
| | - Radovan Smisek
- Department of Biomedical Engineering, Faculty of Electrical Engineering and Communication, Brno University of Technology, Brno, Czechia
| | - Oto Janousek
- Department of Biomedical Engineering, Faculty of Electrical Engineering and Communication, Brno University of Technology, Brno, Czechia
| | - Katerina Fialova
- Department of Physiology, Faculty of Medicine, Masaryk University, Brno, Czechia
| | - Jana Kolarova
- Department of Biomedical Engineering, Faculty of Electrical Engineering and Communication, Brno University of Technology, Brno, Czechia
| | - Marie Novakova
- Department of Physiology, Faculty of Medicine, Masaryk University, Brno, Czechia.,International Clinical Research Center, St. Anne's University Hospital Brno, Brno, Czechia
| | - Ivo Provaznik
- Department of Biomedical Engineering, Faculty of Electrical Engineering and Communication, Brno University of Technology, Brno, Czechia
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6
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Offerhaus JA, Snelderwaard PC, Algül S, Faber JW, Riebel K, Jensen B, Boukens BJ. High heart rate associated early repolarization causes J-waves in both zebra finch and mouse. Physiol Rep 2021; 9:e14775. [PMID: 33709567 PMCID: PMC7953022 DOI: 10.14814/phy2.14775] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 01/22/2021] [Accepted: 02/04/2021] [Indexed: 11/24/2022] Open
Abstract
High heart rates are a feature of small endothermic—or warm‐blooded—mammals and birds. In small mammals, the QT interval is short, and local ventricular recordings reveal early repolarization that coincides with the J‐wave on the ECG, a positive deflection following the QRS complex. Early repolarization contributes to short QT‐intervals thereby enabling brief cardiac cycles and high heart rates. We therefore hypothesized high hearts rates associate with early repolarization and J‐waves on the ECG of endothermic birds. We tested this hypothesis by comparing isolated hearts of zebra finches and mice and recorded pseudo‐ECGs and optical action potentials (zebra finch, n = 8; mouse, n = 8). In both species, heart rate exceeded 300 beats per min, and total ventricular activation was fast (QRS < 10 ms). Ventricular activation progressed from the left to the right ventricle in zebra finch, whereas it progressed from apex‐to‐base in mouse. In both species, the early repolarization front followed the activation front, causing a positive J‐wave in the pseudo‐ECG. Inhibition of early repolarization by 4‐aminopyridine reduced J‐wave amplitude in both species. Action potential duration was similar between ventricles in zebra finch, whereas in mouse the left ventricular action potential was longer. Accordingly, late repolarization had opposite directions in zebra finch (left‐right) and mouse (right‐left). This caused a similar direction for the zebra finch J‐wave and T‐wave, whereas in the mouse they were discordant. Our findings demonstrate that early repolarization and the associated J‐wave may have evolved by convergence in association with high heart rates.
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Affiliation(s)
- Joost A Offerhaus
- Department of Experimental Cardiology, Academic Medical Center, Amsterdam University Medical Center, Amsterdam, Netherlands
| | | | - Sila Algül
- Department of Medical Biology, Academic Medical Center, Amsterdam University Medical Center, Amsterdam, Netherlands
| | - Jaeike W Faber
- Department of Medical Biology, Academic Medical Center, Amsterdam University Medical Center, Amsterdam, Netherlands
| | - Katharina Riebel
- Institute of Biology, Leiden University, Leiden, The Netherlands
| | - Bjarke Jensen
- Department of Medical Biology, Academic Medical Center, Amsterdam University Medical Center, Amsterdam, Netherlands
| | - Bastiaan J Boukens
- Department of Experimental Cardiology, Academic Medical Center, Amsterdam University Medical Center, Amsterdam, Netherlands.,Department of Medical Biology, Academic Medical Center, Amsterdam University Medical Center, Amsterdam, Netherlands
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7
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Dou W, Zhao Q, Malhi M, Liu X, Zhang Z, Wang L, Masse S, Nanthakumar K, Hamilton R, Maynes JT, Sun Y. Label-free conduction velocity mapping and gap junction assessment of functional iPSC-Cardiomyocyte monolayers. Biosens Bioelectron 2020; 167:112468. [PMID: 32829174 DOI: 10.1016/j.bios.2020.112468] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Revised: 07/20/2020] [Accepted: 07/21/2020] [Indexed: 02/06/2023]
Abstract
Cardiac conduction is an important function of the heart. To date, accurate measurement of conduction velocity (CV) in vitro is hindered by the low spatial resolution and poor signal-to-noise ratio of microelectrode arrays (MEAs), or the cytotoxicity and end-point analysis of fluorescence optical imaging. Here, we have developed a new label-free method based on defocused brightfield imaging to quantify CV by analyzing centroid displacements and contraction trajectories of each cardiomyocyte in a monolayer of human stem cell-derived cardiomyocytes (iPSC-CMs). Our data revealed that the time delay between intracellular calcium release and the initiation of cell contraction is highly consistent across cardiomyocytes; however, the duration a cell takes to reach its maximum beating magnitude varies significantly, proving that the time delay in excitation-contraction coupling is largely constant in iPSC-CMs. Standard calcium imaging of the same iPSC-CM populations (~106 cells) was conducted for comparison with our label-free method. The results confirmed that our label-free method was capable of achieving highly accurate CV mapping (17.64 ± 0.89 cm/s vs. 17.95 ± 2.29 cm/s, p-value>0.1). Additionally, our method effectively revealed various shapes in cell beating pattern. We also performed label-free CV mapping on disease-specific iPSC-CM monolayers with plakophilin-2 (PKP2) knockdown, which effectively quantified their low CV values and further validated the arrhythmogenic role of PKP2 mutation in arrhythmogenic right ventricular cardiomyopathy (ARVC) through the disruption of cardiac conduction. The label-free method offers a cytotoxic-free technique for long-term measurement of dynamic beating trajectories, beating propagation and conduction velocities of cardiomyocyte monolayers.
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Affiliation(s)
- Wenkun Dou
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, M5S 3G8, Canada
| | - Qili Zhao
- Institute of Robotics and Automatic Information System and the Tianjin Key Laboratory of Intelligent Robotics, Nankai University, Tianjin, 300071, China
| | - Manpreet Malhi
- Program in Molecular Medicine, Hospital for Sick Children, Toronto, M5G 1X8, Canada; Department of Biochemistry, University of Toronto, Toronto, M5S 1A8, Canada
| | - Xingjian Liu
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, M5S 3G8, Canada
| | - Zhuoran Zhang
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, M5S 3G8, Canada
| | - Li Wang
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, M5S 3G8, Canada
| | | | | | - Robert Hamilton
- Program in Translational Medicine, Hospital for Sick Children, Toronto, M5G 1X8, Canada
| | - Jason T Maynes
- Program in Molecular Medicine, Hospital for Sick Children, Toronto, M5G 1X8, Canada; Department of Biochemistry, University of Toronto, Toronto, M5S 1A8, Canada; Department of Anesthesia and Pain Medicine, Hospital for Sick Children, Toronto, M5G 1X8, Canada.
| | - Yu Sun
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, M5S 3G8, Canada; Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, M5S 3G9, Canada; Department of Electrical and Computer Engineering, University of Toronto, Toronto, M5S 3G4, Canada; Department of Computer Science, University of Toronto, Toronto, M5T 3A1, Canada.
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8
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Hoeker GS, James CC, Tegge AN, Gourdie RG, Smyth JW, Poelzing S. Attenuating loss of cardiac conduction during no-flow ischemia through changes in perfusate sodium and calcium. Am J Physiol Heart Circ Physiol 2020; 319:H396-H409. [PMID: 32678707 DOI: 10.1152/ajpheart.00112.2020] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Myocardial ischemia leads to conduction slowing, cell-to-cell uncoupling, and arrhythmias. We previously demonstrated that varying perfusate sodium (Na+) and calcium (Ca2+) attenuates conduction slowing and arrhythmias during simulated ischemia with continuous perfusion. Cardioprotection was selectively associated with widening of the perinexus, a gap junction adjacent nanodomain important to ephaptic coupling. It is unknown whether perfusate composition affects the perinexus or ischemic conduction during nonsimulated ischemia, when coronary flow is reduced or halted. We hypothesized that altering preischemic perfusate composition could facilitate perinexal expansion and attenuate conduction slowing during global ischemia. To test this hypothesis, ex vivo guinea pig hearts (n = 49) were Langendorff perfused with 145 or 153 mM Na+ and 1.25 or 2.0 mM Ca2+ and optically mapped during 30 min of no-flow ischemia. Altering Na+ and Ca2+ did not substantially affect baseline conduction. Increasing Na+ and decreasing Ca2+ both lowered pacing thresholds, whereas increasing Ca2+ narrowed perinexal width (Wp). A least squares mean estimate revealed that reduced perfusate Na+ and Ca2+ resulted in the most severe conduction slowing during ischemia. Increasing Na+ alone modestly attenuated conduction slowing, yet significantly delayed the median time to conduction block (10 to 16 min). Increasing both Na+ and Ca2+ selectively widened Wp during ischemia (22.7 vs. 15.7 nm) and attenuated conduction slowing to the greatest extent. Neither repolarization nor levels of total or phosphorylated connexin43 correlated with conduction slowing or block. Thus, perfusate-dependent widening of the perinexus preserved ischemic conduction and may be an adaptive response to ischemic stress.NEW & NOTEWORTHY Conduction slowing during acute ischemia creates an arrhythmogenic substrate. We have shown that extracellular ionic concentrations can alter conduction by modulating ephaptic coupling. Here, we demonstrate increased extracellular sodium and calcium significantly attenuate conduction slowing during no-flow ischemia. This effect was associated with selective widening of the perinexus, an intercalated disc nanodomain and putative cardiac ephapse. These findings suggest that acute changes in ephaptic coupling may serve as an adaptive response to ischemic stress.
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Affiliation(s)
- Gregory S Hoeker
- Center for Heart and Reparative Medicine Research, Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, Virginia
| | - Carissa C James
- Center for Heart and Reparative Medicine Research, Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, Virginia.,Translational Biology, Medicine, and Health Graduate Program, Virginia Polytechnic Institute and State University, Roanoke, Virginia
| | - Allison N Tegge
- Virginia Tech Carilion School of Medicine, Roanoke, Virginia.,Department of Statistics, Virginia Polytechnic Institute and State University, Blacksburg, Virginia
| | - Robert G Gourdie
- Center for Heart and Reparative Medicine Research, Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, Virginia.,Virginia Tech Carilion School of Medicine, Roanoke, Virginia.,Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State University, Blacksburg, Virginia
| | - James W Smyth
- Center for Heart and Reparative Medicine Research, Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, Virginia.,Virginia Tech Carilion School of Medicine, Roanoke, Virginia.,Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia
| | - Steven Poelzing
- Center for Heart and Reparative Medicine Research, Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, Virginia.,Translational Biology, Medicine, and Health Graduate Program, Virginia Polytechnic Institute and State University, Roanoke, Virginia.,Virginia Tech Carilion School of Medicine, Roanoke, Virginia.,Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State University, Blacksburg, Virginia
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9
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O'Shea C, Kabir SN, Holmes AP, Lei M, Fabritz L, Rajpoot K, Pavlovic D. Cardiac optical mapping - State-of-the-art and future challenges. Int J Biochem Cell Biol 2020; 126:105804. [PMID: 32681973 PMCID: PMC7456775 DOI: 10.1016/j.biocel.2020.105804] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 07/10/2020] [Accepted: 07/13/2020] [Indexed: 11/06/2022]
Abstract
Cardiac optical mapping is a fluorescent imaging method to study electrical behaviour and calcium handling in the heart. Optical mapping provides higher spatio-temporal resolution than electrode techniques, allowing unique insights into cardiac electrophysiology in health and disease from a variety of pre-clinical models. Both transmembrane voltage and intracellular calcium dynamics can be studied with the use of appropriate fluorescent dyes. Optical mapping has traditionally required the use of mechanical uncouplers, however computational and technical developments have lessened the requirement for these agents. Novel fluorescent dyes have been developed to optimise spectral properties, experimental timescales, biological compatibility and fluorescence output. The combination of these developments has made possible novel mapping experiments, including recent in vivo application of the technique.
Cardiac optical mapping utilises fluorescent dyes to directly image the electrical function of the heart at a high spatio-temporal resolution which far exceeds electrode techniques. It has therefore become an invaluable tool in cardiac electrophysiological research to map the propagation of heterogeneous electrical signals across the myocardium. In this review, we introduce the principles behind cardiac optical mapping and discuss some of the challenges and state of the art in the field. Key advancements discussed include newly developed fluorescent indicators, tools for the analysis of complex datasets, panoramic imaging systems and technical and computational approaches to realise optical mapping in freely beating hearts.
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Affiliation(s)
- Christopher O'Shea
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK
| | - S Nashitha Kabir
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK
| | - Andrew P Holmes
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK; Institute of Clinical Sciences, University of Birmingham, Birmingham, UK
| | - Ming Lei
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Larissa Fabritz
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK; Department Cardiology, University Hospital Birmingham, Birmingham, UK
| | - Kashif Rajpoot
- School of Computer Science, University of Birmingham, Birmingham, UK
| | - Davor Pavlovic
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK.
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10
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Two-photon excitation of FluoVolt allows improved interrogation of transmural electrophysiological function in the intact mouse heart. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2019; 154:11-20. [PMID: 31492464 PMCID: PMC7322535 DOI: 10.1016/j.pbiomolbio.2019.08.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 07/17/2019] [Accepted: 08/15/2019] [Indexed: 11/21/2022]
Abstract
BACKGROUND & AIMS Two-photon excitation of voltage sensitive dyes (VSDs) can measure rapidly changing electrophysiological signals deep within intact cardiac tissue with improved three-dimensional resolution along with reduced photobleaching and photo-toxicity compared to conventional confocal microscopy. Recently, a category of VSDs has emerged which records membrane potentials by photo-induced electron transfer. FluoVolt is a novel VSD in this category which promises fast response and a 25% fractional change in fluorescence per 100 mV, making it an attractive optical probe for action potential (AP) recordings within intact cardiac tissue. The purpose of this study was to characterize the fluorescent properties of FluoVolt as well as its utility for deep tissue imaging. METHODS Discrete tissue layers throughout the left ventricular wall of isolated perfused murine hearts loaded with FluoVolt or di-4-ANEPPS were sequentially excited with two-photon microscopy. RESULTS FluoVolt loaded hearts suffered significantly fewer episodes of atrio-ventricular block compared to di-4-ANEPPS loaded hearts, indicating comparatively low toxicity of FluoVolt in the intact heart. APs recorded with FluoVolt were characterized by a lower signal-to-noise ratio and a higher dynamic range compared to APs recorded with di-4-ANEPPS. Although both depolarization and repolarization parameters were similar in APs recorded with either dye, FluoVolt allowed deeper tissue excitation with improved three-dimensional resolution due to reduced out-of-focus fluorescence generation under two-photon excitation. CONCLUSION Our results demonstrate several advantages of two-photon excitation of FluoVolt in functional studies in intact heart preparations, including reduced toxicity and improved fluorescent properties.
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Optimization of Fluorescent Labeling for In Vivo Nanoimaging of Sarcomeres in the Mouse Heart. BIOMED RESEARCH INTERNATIONAL 2018; 2018:4349170. [PMID: 30211223 PMCID: PMC6126089 DOI: 10.1155/2018/4349170] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Accepted: 06/13/2018] [Indexed: 11/18/2022]
Abstract
The present study was conducted to systematically investigate the optimal viral titer as well as the volume of the adenovirus vector (ADV) that expresses α-actinin-AcGFP in the Z-disks of myocytes in the left ventricle (LV) of mice. An injection of 10 μL ADV at viral titers of 2 to 4 × 1011 viral particles per mL (VP/mL) into the LV epicardial surface consistently expressed α-actinin-AcGFP in myocytes in vivo, with the fraction of AcGFP-expressing myocytes at ~10%. Our analysis revealed that SL was ~1.90-2.15 μm upon heart arrest via deep anesthesia. Likewise, we developed a novel fluorescence labeling method of the T-tubular system by treating the LV surface with CellMask Orange (CellMask). We found that the T-tubular distance was ~2.10-2.25 μm, similar to SL, in the healthy heart in vivo. Therefore, the present high-precision visualization method for the Z-disks or the T-tubules is beneficial to unveiling the mechanisms of myocyte contraction in health and disease in vivo.
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Thomas K, Goudy J, Henley T, Bressan M. Optical Electrophysiology in the Developing Heart. J Cardiovasc Dev Dis 2018; 5:E28. [PMID: 29751595 PMCID: PMC6023508 DOI: 10.3390/jcdd5020028] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Revised: 04/24/2018] [Accepted: 04/26/2018] [Indexed: 12/16/2022] Open
Abstract
The heart is the first organ system to form in the embryo. Over the course of development, cardiomyocytes with differing morphogenetic, molecular, and physiological characteristics are specified and differentiate and integrate with one another to assemble a coordinated electromechanical pumping system that can function independently of any external stimulus. As congenital malformation of the heart presents the leading class of birth defects seen in humans, the molecular genetics of heart development have garnered much attention over the last half century. However, understanding how genetic perturbations manifest at the level of the individual cell function remains challenging to investigate. Some of the barriers that have limited our capacity to construct high-resolution, comprehensive models of cardiac physiological maturation are rapidly being removed by advancements in the reagents and instrumentation available for high-speed live imaging. In this review, we briefly introduce the history of imaging approaches for assessing cardiac development, describe some of the reagents and tools required to perform live imaging in the developing heart, and discuss how the combination of modern imaging modalities and physiological probes can be used to scale from subcellular to whole-organ analysis. Through these types of imaging approaches, critical insights into the processes of cardiac physiological development can be directly examined in real-time. Moving forward, the synthesis of modern molecular biology and imaging approaches will open novel avenues to investigate the mechanisms of cardiomyocyte maturation, providing insight into the etiology of congenital heart defects, as well as serving to direct approaches for designing stem-cell or regenerative medicine protocols for clinical application.
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Affiliation(s)
- Kandace Thomas
- Department of Cell Biology and Physiology, McAllister Heart Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
| | - Julie Goudy
- Department of Cell Biology and Physiology, McAllister Heart Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
| | - Trevor Henley
- Department of Cell Biology and Physiology, McAllister Heart Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
| | - Michael Bressan
- Department of Cell Biology and Physiology, McAllister Heart Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
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Tsemperouli M, Sugihara K. Characterization of di-4-ANEPPS with nano-black lipid membranes. NANOSCALE 2018; 10:1090-1098. [PMID: 29271448 DOI: 10.1039/c7nr05863b] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report a platform based on lateral nano-black lipid membranes (nano-BLMs), where electrical measurements and fluorescence microscopy setup are combined, for the calibration of di-4-ANEPPS, a common voltage sensitive dye (VSD). The advantage of this setup is (1) its flexibility in the choice of lipids and applied voltages, (2) its high stability that enables a high voltage (500 mV) application and long-time measurements and (3) its fluorescence microscopy readout, which can be directly correlated with other fluorescence microscopy experiments using VSDs (e.g. membrane potential measurements in living cells). Using this setup, we observed that the calibration curve of di-4-ANEPPS is strongly dependent on the net electric charge of the lipids. The developed setup can be used to calibrate VSDs in different lipid environments in order to better understand their fundamental voltage-sensing mechanism in the future.
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Affiliation(s)
- Maria Tsemperouli
- Department of Physical Chemistry, University of Geneva, Quai Ernest Ansermet 30, 1211 Geneva 4, Switzerland.
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14
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George SA, Calhoun PJ, Gourdie RG, Smyth JW, Poelzing S. TNFα Modulates Cardiac Conduction by Altering Electrical Coupling between Myocytes. Front Physiol 2017; 8:334. [PMID: 28588504 PMCID: PMC5440594 DOI: 10.3389/fphys.2017.00334] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 05/08/2017] [Indexed: 12/22/2022] Open
Abstract
Background: Tumor Necrosis Factor α (TNFα) upregulation during acute inflammatory response has been associated with numerous cardiac effects including modulating Connexin43 and vascular permeability. This may in turn alter cardiac gap junctional (GJ) coupling and extracellular volume (ephaptic coupling) respectively. We hypothesized that acute exposure to pathophysiological TNFα levels can modulate conduction velocity (CV) in the heart by altering electrical coupling: GJ and ephaptic. Methods and Results: Hearts were optically mapped to determine CV from control, TNFα and TNFα + high calcium (2.5 vs. 1.25 mM) treated guinea pig hearts over 90 mins. Transmission electron microscopy was performed to measure changes in intercellular separation in the gap junction-adjacent extracellular nanodomain—perinexus (WP). Cx43 expression and phosphorylation were determined by Western blotting and Cx43 distribution by confocal immunofluorescence. At 90 mins, longitudinal and transverse CV (CVL and CVT, respectively) increased with control Tyrode perfusion but TNFα slowed CVT alone relative to control and anisotropy of conduction increased, but not significantly. TNFα increased WP relative to control at 90 mins, without significantly changing GJ coupling. Increasing extracellular calcium after 30 mins of just TNFα exposure increased CVT within 15 mins. TNFα + high calcium also restored CVT at 90 mins and reduced WP to control values. Interestingly, TNFα + high calcium also improved GJ coupling at 90 mins, which along with reduced WP may have contributed to increasing CV. Conclusions: Elevating extracellular calcium during acute TNFα exposure reduces perinexal expansion, increases ephaptic, and GJ coupling, improves CV and may be a novel method for preventing inflammation induced CV slowing.
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Affiliation(s)
- Sharon A George
- Department of Biomedical Engineering and Sciences, Virginia Polytechnic Institute and State UniversityBlacksburg, VA, United States
| | - Patrick J Calhoun
- Department of Biological Sciences, Virginia Polytechnic Institute and State UniversityBlacksburg, VA, United States
| | - Robert G Gourdie
- Department of Biomedical Engineering and Sciences, Virginia Polytechnic Institute and State UniversityBlacksburg, VA, United States.,Center for Heart and Regenerative Medicine, Virginia Tech Carilion Research InstituteRoanoke, VA, United States
| | - James W Smyth
- Center for Heart and Regenerative Medicine, Virginia Tech Carilion Research InstituteRoanoke, VA, United States
| | - Steven Poelzing
- Department of Biomedical Engineering and Sciences, Virginia Polytechnic Institute and State UniversityBlacksburg, VA, United States.,Center for Heart and Regenerative Medicine, Virginia Tech Carilion Research InstituteRoanoke, VA, United States
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Abstract
Small-conductance Ca2+-activated potassium (SK) channels are relative newcomers within the field of cardiac electrophysiology. In recent years, an increased focus has been given to these channels because they might constitute a relatively atrial-selective target. This review will give a general introduction to SK channels followed by their proposed function in the heart under normal and pathophysiological conditions. It is revealed how antiarrhythmic effects can be obtained by SK channel inhibition in a number of species in situations of atrial fibrillation. On the contrary, the beneficial effects of SK channel inhibition in situations of heart failure are questionable and still needs investigation. The understanding of cardiac SK channels is rapidly increasing these years, and it is hoped that this will clarify whether SK channel inhibition has potential as a new anti–atrial fibrillation principle.
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Angel N, Li LI, Macleod RS, Marrouche N, Ranjan R, Dosdall DJ. Diverse Fibrosis Architecture and Premature Stimulation Facilitate Initiation of Reentrant Activity Following Chronic Atrial Fibrillation. J Cardiovasc Electrophysiol 2015; 26:1352-60. [PMID: 26249367 DOI: 10.1111/jce.12773] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Revised: 07/20/2015] [Accepted: 07/26/2015] [Indexed: 11/26/2022]
Abstract
INTRODUCTION Patients with paroxysmal atrial fibrillation (AF) often transition between sinus rhythm and AF. For AF to initiate there must be both a trigger and a substrate that facilitates reentrant activity. This trigger is often caused by a premature atrial contraction or focal activations within the atrium. We hypothesize that specific architectures of fibrosis alter local conduction to enable AF. METHODS AND RESULTS Control goats (n = 13) and goats in chronic AF (for an average of 6 months, n = 6) had a high-density electrode plaque placed on the LA appendage. Conduction patterns following a premature atrial contraction, caused by an electrical stimulation, were quantified to determine regions of conduction slowing. These regions were compared to architecture, either diffuse fibrosis or regions of obstructive fibrosis, and overall fibrosis levels as determined by histology from the mapped region. The chronic AF goats had more obstructive fibrosis than the controls (17.5 ± 8.0 fibers/mm(2) vs. 8.6 ± 3.0 fibers/mm(2)). Conduction velocity of the AF goats was significantly slowed compared to the control goats in the transverse direction (0.40 ± 0.04 m/s vs. 0.53 ± 0.15 m/s) but not in the longitudinal direction (0.70 ± 0.27 m/s vs. 0.76 ± 0.18 m/s). CONCLUSIONS AF-induced atrial remodeling leads to increased obstructive fibrosis and conduction velocity slowing transverse to fiber orientation following premature stimuli. The decrease in conduction velocity causes a decrease in the cardiac wavelength, and increases the likelihood of reentry and AF onset.
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Affiliation(s)
- Nathan Angel
- Comprehensive Arrhythmia Research & Management Center, Division of Cardiovascular Medicine, Salt Lake City, Utah, USA.,Department of Bioengineering, University of Utah, Salt Lake City, Utah, USA
| | - L I Li
- Comprehensive Arrhythmia Research & Management Center, Division of Cardiovascular Medicine, Salt Lake City, Utah, USA
| | - Rob S Macleod
- Comprehensive Arrhythmia Research & Management Center, Division of Cardiovascular Medicine, Salt Lake City, Utah, USA.,Department of Bioengineering, University of Utah, Salt Lake City, Utah, USA
| | - Nassir Marrouche
- Comprehensive Arrhythmia Research & Management Center, Division of Cardiovascular Medicine, Salt Lake City, Utah, USA.,Center for Engineering Innovation, Salt Lake City, Utah, USA
| | - Ravi Ranjan
- Comprehensive Arrhythmia Research & Management Center, Division of Cardiovascular Medicine, Salt Lake City, Utah, USA.,Department of Bioengineering, University of Utah, Salt Lake City, Utah, USA
| | - Derek J Dosdall
- Comprehensive Arrhythmia Research & Management Center, Division of Cardiovascular Medicine, Salt Lake City, Utah, USA.,Center for Engineering Innovation, Salt Lake City, Utah, USA.,Department of Bioengineering, University of Utah, Salt Lake City, Utah, USA
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Vostarek F, Sankova B, Sedmera D. Studying dynamic events in the developing myocardium. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2014; 115:261-9. [PMID: 24954141 DOI: 10.1016/j.pbiomolbio.2014.06.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2014] [Accepted: 06/10/2014] [Indexed: 01/25/2023]
Abstract
Differentiation and conduction properties of the cardiomyocytes are critically dependent on physical conditioning both in vitro and in vivo. Historically, various techniques were introduced to study dynamic events such as electrical currents and changes in ionic concentrations in live cells, multicellular preparations, or entire hearts. Here we review this technological progress demonstrating how each improvement in spatial or temporal resolution provided answers to old and provoked new questions. We further demonstrate how high-speed optical mapping of voltage and calcium can uncover pacemaking potential within the outflow tract myocardium, providing a developmental explanation of ectopic beats originating from this region in the clinical settings.
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Affiliation(s)
- Frantisek Vostarek
- Institute of Physiology, Academy of Sciences of the Czech Republic, Czech Republic; Faculty of Science, Charles University, Prague, Czech Republic
| | - Barbora Sankova
- Institute of Physiology, Academy of Sciences of the Czech Republic, Czech Republic; Institute of Anatomy, First Medical Faculty, Charles University, Prague, Czech Republic
| | - David Sedmera
- Institute of Physiology, Academy of Sciences of the Czech Republic, Czech Republic; Institute of Anatomy, First Medical Faculty, Charles University, Prague, Czech Republic.
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18
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Abstract
In the past decade, optical mapping provided crucial mechanistic insight into electromechanical function and the mechanism of ventricular fibrillation. Therefore, to date, optical mapping dominates experimental cardiac electrophysiology. The first cardiac measurements involving optics were done in the early 1900s using the fast cinematograph that later evolved into methods for high-resolution activation and repolarization mapping and stimulation of specific cardiac cell types. The field of "optocardiography," therefore, emerged as the use of light for recording or interfering with cardiac physiology. In this review, we discuss how optocardiography developed into the dominant research technique in experimental cardiology. Furthermore, we envision how optocardiographic methods can be used in clinical cardiology.
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Bingen BO, Askar SFA, Schalij MJ, de Vries AAF, Pijnappels DA. Prolongation of minimal action potential duration in sustained fibrillation decreases complexity by transient destabilization: reply. Cardiovasc Res 2013; 98:156-7. [PMID: 23396603 DOI: 10.1093/cvr/cvt027] [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] [Indexed: 11/15/2022] Open
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20
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Wolkowicz PE, Umeda PK, Sharifov OF, Wang P, Mahtani H, Urthaler F. Prolongation of minimal action potential duration in sustained fibrillation decreases complexity by transient destabilization. Cardiovasc Res 2013; 98:155-6. [DOI: 10.1093/cvr/cvt022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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21
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Sohn K, Wende AR, Abel ED, Moreno AP, Sachse FB, Punske BB. Absence of glucose transporter 4 diminishes electrical activity of mouse hearts during hypoxia. Exp Physiol 2012. [PMID: 23180812 DOI: 10.1113/expphysiol.2012.070235] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Insulin resistance, which characterizes type 2 diabetes, is associated with reduced translocation of glucose transporter 4 (GLUT4) to the plasma membrane following insulin stimulation, and diabetic patients with insulin resistance show a higher incidence of ischaemia, arrhythmias and sudden cardiac death. The aim of this study was to examine whether GLUT4 deficiency leads to more severe alterations in cardiac electrical activity during cardiac stress due to hypoxia. To fulfil this aim, we compared cardiac electrical activity from cardiac-selective GLUT4-ablated (G4H-/-) mouse hearts and corresponding control (CTL) littermates. A custom-made cylindrical 'cage' electrode array measured potentials (Ves) from the epicardium of isolated, perfused mouse hearts. The normalized average of the maximal downstroke of Ves ( (|d Ves/dt(min)|na), which we previously introduced as an index of electrical activity in normal, ischaemic and hypoxic hearts, was used to assess the effects of GLUT4 deficiency on electrical activity. The |d Ves/dt(min)|na of G4H −/− and CTL hearts decreased by 75 and 47%, respectively (P < 0.05), 30 min after the onset of hypoxia. Administration of insulin attenuated decreases in values of |d Ves/dt(min)|na in G4H −/− hearts as well as in CTL hearts, during hypoxia. In general, however, G4H −/− hearts showed a severe alteration of the propagation sequence and a prolonged total activation time. Results of this study demonstrate that reduced glucose availability associated with insulin resistance and a reduction in GLUT4-mediated glucose transport impairs electrical activity during hypoxia, and may contribute to cardiac vulnerability to arrhythmias in diabetic patients.
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Affiliation(s)
- Kwanghyun Sohn
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, 95 South 2000 East, Salt Lake City, UT 84112-5000, USA.
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