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Dong X, Tse G, Hao G, Du Y. Heterogeneities in Ventricular Conduction Following Treatment with Heptanol: A Multi-Electrode Array Study in Langendorff-Perfused Mouse Hearts. Life (Basel) 2022; 12:life12070996. [PMID: 35888085 PMCID: PMC9321110 DOI: 10.3390/life12070996] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 06/21/2022] [Accepted: 06/30/2022] [Indexed: 11/26/2022] Open
Abstract
Background: Previous studies have associated slowed ventricular conduction with the arrhythmogenesis mediated by the gap junction and sodium channel inhibitor heptanol in mouse hearts. However, they did not study the propagation patterns that might contribute to the arrhythmic substrate. This study used a multi-electrode array mapping technique to further investigate different conduction abnormalities in Langendorff-perfused mouse hearts exposed to 0.1 or 2 mM heptanol. Methods: Recordings were made from the left ventricular epicardium using multi-electrode arrays in spontaneously beating hearts during right ventricular 8 Hz pacing or S1S2 pacing. Results: In spontaneously beating hearts, heptanol at 0.1 and 2 mM significantly reduced the heart rate from 314 ± 25 to 189 ± 24 and 157 ± 7 bpm, respectively (ANOVA, p < 0.05 and p < 0.001). During regular 8 Hz pacing, the mean LATs were increased by 0.1 and 2 mM heptanol from 7.1 ± 2.2 ms to 19.9 ± 5.0 ms (p < 0.05) and 18.4 ± 5.7 ms (p < 0.05). The standard deviation of the mean LATs was increased from 2.5 ± 0.8 ms to 10.3 ± 4.0 ms and 8.0 ± 2.5 ms (p < 0.05), and the median of phase differences was increased from 1.7 ± 1.1 ms to 13.9 ± 7.8 ms and 12.1 ± 5.0 ms by 0.1 and 2 mM heptanol (p < 0.05). P5 took a value of 0.2 ± 0.1 ms and was not significantly altered by heptanol at 0.1 or 2 mM (1.1 ± 0.9 ms and 0.9 ± 0.5 ms, p > 0.05). P50 was increased from 7.3 ± 2.7 ms to 24.0 ± 12.0 ms by 0.1 mM heptanol and then to 22.5 ± 7.5 ms by 2 mM heptanol (p < 0.05). P95 was increased from 1.7 ± 1.1 ms to 13.9 ± 7.8 ms by 0.1 mM heptanol and to 12.1 ± 5.0 ms by 2 mM heptanol (p < 0.05). These changes led to increases in the absolute inhomogeneity in conduction (P5−95) from 7.1 ± 2.6 ms to 31.4 ± 11.3 ms, 2 mM: 21.6 ± 7.2 ms, respectively (p < 0.05). The inhomogeneity index (P5−95/P50) was significantly reduced from 3.7 ± 1.2 to 3.1 ± 0.8 by 0.1 mM and then to 3.3 ± 0.9 by 2 mM heptanol (p < 0.05). Conclusion: Increased activation latencies, reduced CVs, and the increased inhomogeneity index of conduction were associated with both spontaneous and induced ventricular arrhythmias.
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Affiliation(s)
- Xiuming Dong
- Henan SCOPE Research Institute of Electrophysiology Co., Ltd., Kaifeng 475000, China; (X.D.); (G.H.)
| | - Gary Tse
- Cardiac Electrophysiology Unit, Cardiovascular Analytics Group, Hong Kong, China;
- Tianjin Key Laboratory of Ionic-Molecular Function of Cardiovascular Disease, Department of Cardiology, Tianjin Institute of Cardiology, Second Hospital of Tianjin Medical University, Tianjin 300211, China
- Kent and Medway Medical School, Canterbury CT2 7FS, UK
| | - Guoliang Hao
- Henan SCOPE Research Institute of Electrophysiology Co., Ltd., Kaifeng 475000, China; (X.D.); (G.H.)
- Burdon Sanderson Cardiac Science Centre, BHF Centre of Research Excellence, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, UK
| | - Yimei Du
- Department of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
- Research Center of Ion Channelopathy, Institute of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
- Correspondence:
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Zhong JQ, Laurent G, So PPS, Hu X, Hennan JK, Dorian P. Effects of Rotigaptide, a Gap Junction Modifier, on Defibrillation Energy and Resuscitation From Cardiac Arrest in Rabbits. J Cardiovasc Pharmacol Ther 2016; 12:69-77. [PMID: 17495260 DOI: 10.1177/1074248406298021] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The gap junction modifier Rotigaptide (ZP123), which promotes cellular coupling, was hypothesized to decrease defibrillation thresholds during prolonged ventricular fibrillation (VF). Thirty-two New Zealand white rabbits were randomized to receive saline (control, n = 16) or Rotigaptide (n = 16). Following 4 min of untreated VF, biphasic defibrillation shocks were applied through chest wall patches, starting either at 300 volts (V) (n = 16) or 500 V (n = 16), with 200 V increasing steps to 900 V in case of shock failure. Rotigaptide significantly decreased defibrillation voltage requirements (average cumulative voltage of all shocks: 1206 ± 709 V in control group vs. 844 ± 546 V in treated group, P = .002). Rotigaptide had no effect on heart rate, QRS duration, QT interval, ventricular effective refractory period, monophasic action potential duration or on connexin 43 density using immunofluorescence. Rotigaptide improves the ability to defibrillate after untreated VF.
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Affiliation(s)
- Jing-quan Zhong
- Department of Medicine, University of Toronto and Division of Cardiology, St. Michael's Hospital, 30 Bond Street, Toronto, Ontario, Canada
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Pilarczyk G, Raulf A, Gunkel M, Fleischmann BK, Lemor R, Hausmann M. Tissue-Mimicking Geometrical Constraints Stimulate Tissue-Like Constitution and Activity of Mouse Neonatal and Human-Induced Pluripotent Stem Cell-Derived Cardiac Myocytes. J Funct Biomater 2016; 7:E1. [PMID: 26751484 PMCID: PMC4810060 DOI: 10.3390/jfb7010001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Revised: 12/17/2015] [Accepted: 12/18/2015] [Indexed: 12/15/2022] Open
Abstract
The present work addresses the question of to what extent a geometrical support acts as a physiological determining template in the setup of artificial cardiac tissue. Surface patterns with alternating concave to convex transitions of cell size dimensions were used to organize and orientate human-induced pluripotent stem cell (hIPSC)-derived cardiac myocytes and mouse neonatal cardiac myocytes. The shape of the cells, as well as the organization of the contractile apparatus recapitulates the anisotropic line pattern geometry being derived from tissue geometry motives. The intracellular organization of the contractile apparatus and the cell coupling via gap junctions of cell assemblies growing in a random or organized pattern were examined. Cell spatial and temporal coordinated excitation and contraction has been compared on plain and patterned substrates. While the α-actinin cytoskeletal organization is comparable to terminally-developed native ventricular tissue, connexin-43 expression does not recapitulate gap junction distribution of heart muscle tissue. However, coordinated contractions could be observed. The results of tissue-like cell ensemble organization open new insights into geometry-dependent cell organization, the cultivation of artificial heart tissue from stem cells and the anisotropy-dependent activity of therapeutic compounds.
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Affiliation(s)
- Götz Pilarczyk
- Kirchhoff Institute für Physik, Im Neuenheimer Feld INF 270, Heidelberg D-69120, Germany.
| | - Alexandra Raulf
- Institut für Physiologie der Unversität Bonn, Life & Brain Center, Sigmund Freud Strasse 25, Bonn D-53127, Germany.
| | - Manuel Gunkel
- ViroQuant Cell Networks RNAi Screening Facility, BioQuant Center, Im Neuenheimer Feld INF 267, Heidelberg D-69120, Germany.
| | - Bernd K Fleischmann
- Institut für Physiologie der Unversität Bonn, Life & Brain Center, Sigmund Freud Strasse 25, Bonn D-53127, Germany.
| | - Robert Lemor
- Luxembourg Institute for Science and Technology, 5 avenue des Hauts-Fourneaux, Esch-Belval L-4362, Luxembourg.
| | - Michael Hausmann
- Kirchhoff Institute für Physik, Im Neuenheimer Feld INF 270, Heidelberg D-69120, Germany.
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Yamashita S, Yoshida A, Fukuzawa K, Nakanishi T, Matsumoto A, Konishi H, Ichibori H, Hyogo K, Imada H, Hirata KI. The Relationship Between Cardiac Vulnerability and Restitution Properties of the Ventricular Activation Recovery Interval. J Cardiovasc Electrophysiol 2015; 26:768-73. [PMID: 25810143 DOI: 10.1111/jce.12672] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Revised: 03/05/2015] [Accepted: 03/13/2015] [Indexed: 12/01/2022]
Abstract
INTRODUCTION The restitution of the action potential duration (APD) is an important contributor to ventricular fibrillation (VF) initiation by a single critically timed ectopic beat. We hypothesized that a steep slope of the activation recovery interval restitution curve was related to the upper limit of vulnerability (ULV). METHODS AND RESULTS Fifty-four consecutive patients with implantable cardioverter defibrillators (ICDs) implanted between April 2012 and July 2013 were included. At the implantation, pacing from the right ventricular (RV) coil to an indifferent electrode inserted in the ICD pocket was performed, and the unipolar electrograms from the RV coil were simultaneously recorded. We assessed the standard restitution by introducing extra-stimuli, while measuring the activation recovery interval (ARI). Our protocol for the vulnerability test consisted of delivering three 15 J shocks on the T-peak and within ±20 milliseconds of it. If VF was not induced by that procedure, a ULV of ≤15 J was defined. The relationship between the ULV and maximum slope of the restitution curve was analyzed. A restitution curve could finally be obtained in a total of 40 patients. The background characteristics were similar between the two groups. The maximum slope of the restitution curve was steeper in the ULV > 15 J group than ULV ≤ 15 J group (1.55 ± 0.45 vs. 0.91 ± 0.64, P < 0.05). A maximum slope exceeding 1.0 was the optimal point for discriminating patients with a ULV > 15 J from a ULV ≤ 15 J (sensitivity 61.5% and specificity 96.3%). CONCLUSION The maximum slope of the restitution curve was significantly related to the ULV. High defibrillation threshold patients could be detected by the ARI dynamics.
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Affiliation(s)
- Soichiro Yamashita
- Division of Cardiovascular Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Akihiro Yoshida
- Division of Cardiovascular Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Koji Fukuzawa
- Division of Cardiovascular Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Tomoyuki Nakanishi
- Division of Cardiovascular Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Akinori Matsumoto
- Division of Cardiovascular Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Hiroki Konishi
- Division of Cardiovascular Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Hirotoshi Ichibori
- Division of Cardiovascular Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Kiyohiro Hyogo
- Division of Cardiovascular Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Hiroshi Imada
- Division of Cardiovascular Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Ken-Ichi Hirata
- Division of Cardiovascular Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
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Morgan KY, Black LD. Investigation into the effects of varying frequency of mechanical stimulation in a cycle-by-cycle manner on engineered cardiac construct function. J Tissue Eng Regen Med 2014; 11:342-353. [PMID: 24916022 DOI: 10.1002/term.1915] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Revised: 01/17/2014] [Accepted: 04/22/2014] [Indexed: 11/07/2022]
Abstract
Mechanical stimulation has been used extensively to improve the function of cardiac engineered tissue, as it mimics the physical environment in which the tissue is situated during normal development. However, previous mechanical stimulation has been carried out under a constant frequency that more closely resembles a diseased heart. The goal of this study was to create a bioreactor system that would allow us to control the mechanical stimulation of engineered cardiac tissue on a cycle-by-cycle basis. This unique system allows us to determine the effects on cardiac construct function of introducing variability to the mechanical stretch. To test our bioreactor system, constructs created from neonatal rat cardiomyocytes entrapped in fibrin hydrogels were stimulated under various regimes for 2 weeks and then assessed for functional outcomes. No differences were observed in the final cell number in each condition, indicating that variability in frequency did not have a negative effect on viability. The forces were higher for all mechanical stimulation groups compared to static controls, although no differences were observed between the mechanically stimulated conditions, indicating that variable frequency on a cycle-by-cycle basis has limited effects on the resulting force. Although differences in the observed twitch force were not observed, differences in the protein expression indicate that variable-frequency mechanical stimulation had an effect on cell-cell coupling and growth pathway activation in the constructs. Thus, this bioreactor system provides a valuable tool for further development and optimization of engineered myocardial tissue as a repair or replacement strategy for patients undergoing heart failure. Copyright © 2014 John Wiley & Sons, Ltd.
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Affiliation(s)
- Kathy Ye Morgan
- Department of Biomedical Engineering, Tufts University, Medford, MA, USA
| | - Lauren Deems Black
- Department of Biomedical Engineering, Tufts University, Medford, MA, USA.,Cellular, Molecular and Developmental Biology Program, Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, Boston, MA, USA
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Sun B, Qi X, Jiang J. Heptanol decreases the incidence of ischemia-induced ventricular arrhythmias through altering electrophysiological properties and connexin 43 in rat hearts. Biomed Rep 2014; 2:349-353. [PMID: 24748973 PMCID: PMC3990195 DOI: 10.3892/br.2014.247] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2014] [Accepted: 02/27/2014] [Indexed: 11/13/2022] Open
Abstract
Heptanol is a type of gap junction inhibitor that decreases electrical conduction velocity. However, little is known regarding the effects of heptanol on the arrhythmias induced by regional myocardial ischemia. This study aimed to investigate the effects of heptanol on ventricular arrhythmias and the underlying mechanisms. On the Langendorff apparatus, isolated hearts of Sprague-Dawley rats underwent 30 min of ischemia, with or without pretreatment with heptanol (0.1, 0.3 or 0.5 mM), 15 min prior to the induction of regional ischemia through ligation of the left anterior descending coronary artery. The incidence of ventricular tachycardia (VT) and ventricular fibrillation (VF) were recorded after ligation. Heptanol decreased the incidence of ventricular arrhythmias (45% in the control group vs. 10% in the 0.1 mM group, 0% in the 0.3 mM group and 0% in the 0.5 mM group, P<0.05), whereas it prolonged the PR interval, QT interval and monophasic action potential duration at 90% repolarization (MAPD90). As evaluated with immunofluorescence microscopy, heptanol was able to partly reverse the downregulation of connexin 43 (Cx43) induced by ischemia. The results of the reverse transcription-polymerase chain reaction were consistent with those of immunofluorescence. In conclusion, heptanol significantly decreased the incidence of VT and VF induced by regional ischemia and prolonged the PR interval, QT interval and MAPD90. Heptanol also partly reversed the downregulation of Cx43 induced by ischemia.
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Affiliation(s)
- Bing Sun
- Department of Cardiology, Tongji Hospital, Tongji University, Shanghai, P.R. China
| | - Xiangqian Qi
- Department of Cardiology, Taida Cardiology Hospital, Tianjin, P.R. China
| | - Jinfa Jiang
- Department of Cardiology, Tongji Hospital, Tongji University, Shanghai, P.R. China
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Zhang X, Wang Q, Gablaski B, Zhang X, Lucchesi P, Zhao Y. A microdevice for studying intercellular electromechanical transduction in adult cardiac myocytes. LAB ON A CHIP 2013; 13:3090-7. [PMID: 23753064 PMCID: PMC3770274 DOI: 10.1039/c3lc50414j] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Intercellular electromechanical transduction in adult cardiac myocytes plays an important role in regulating heart function. The efficiency of intercellular electromechanical transduction has so far been investigated only to a limited extent, which is largely due to the lack of appropriate tools that can quantitatively assess the contractile performance of interconnected adult cardiac myocytes. In this paper we report a microengineered device that is capable of applying electrical stimulation to the selected adult cardiac myocyte in a longitudinally connected cell doublet and quantifying the intercellular electromechanical transduction by measuring the contractile performance of stimulated and un-stimulated cells in the same doublet. The capability of applying selective electrical stimulation on only one cell in the doublet is validated by examining cell contractile performance while blocking the intercellular communication. Quantitative assessment of cell contractile performance in isolated adult cardiac myocytes is performed by measuring the change in cell length. The proof-of-concept assessment of gap junction performance shows that the device is useful in studying the efficiency of gap junctions in adult cardiac myocytes, which is most relevant to the synchronized pumping performance of native myocardium. Collectively, this work provides a quantitative tool for studying intercellular electromechanical transduction and is expected to develop a comprehensive understanding of the role of intercellular communication in various heart diseases.
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Affiliation(s)
- Xu Zhang
- Laboratory for Biomedical Microsystems, Department of Biomedical Engineering, The Ohio State University, Columbus, OH, 43210 USA
| | - Qian Wang
- Laboratory for Biomedical Microsystems, Department of Biomedical Engineering, The Ohio State University, Columbus, OH, 43210 USA
| | - Brian Gablaski
- Center for Cardiovascular and Pulmonary Research, Nationwide Children’s Hospital, Columbus, OH, 43205 USA
| | - Xiaojin Zhang
- Center for Cardiovascular and Pulmonary Research, Nationwide Children’s Hospital, Columbus, OH, 43205 USA
| | - Pamela Lucchesi
- Center for Cardiovascular and Pulmonary Research, Nationwide Children’s Hospital, Columbus, OH, 43205 USA
| | - Yi Zhao
- Laboratory for Biomedical Microsystems, Department of Biomedical Engineering, The Ohio State University, Columbus, OH, 43210 USA
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De Vuyst E, Boengler K, Antoons G, Sipido KR, Schulz R, Leybaert L. Pharmacological modulation of connexin-formed channels in cardiac pathophysiology. Br J Pharmacol 2011; 163:469-83. [PMID: 21265827 PMCID: PMC3101610 DOI: 10.1111/j.1476-5381.2011.01244.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2010] [Revised: 12/09/2010] [Accepted: 01/02/2011] [Indexed: 12/17/2022] Open
Abstract
Coordinated electrical activity in the heart is supported by gap junction channels located at the intercalated discs of cardiomyocytes. Impaired gap junctional communication between neighbouring cardiomyocytes contributes to the development of re-entry arrhythmias after myocardial ischaemia. Current antiarrhythmic therapy is hampered by a lack of efficiency and side effects, creating the need for a new generation of drugs. In this review, we focus on compounds that increase gap junctional communication, thereby increasing the conduction velocity and decreasing the risk of arrhythmias. Some of these compounds also inhibit connexin 43 (Cx43) hemichannels, thereby limiting adenosine triphosphate loss and volume overload following ischaemia/reperfusion, thus potentially increasing the survival of cardiomyocytes. The compounds discussed in this review are: (i) antiarrythmic peptide (AAP), AAP10, ZP123; (ii) GAP-134; (iii) RXP-E; and (vi) the Cx mimetic peptides Gap 26 and Gap 27. None of these compounds have effects on Na(+) , Ca(2+) and K(+) channels, and therefore have no proarrhythmic activity associated with currently available antiarrhythmic drugs. GAP-134, RXP-E, Gap 26 and Gap 27 are pharmalogical agents with a favorable clinical safety profile, as already confirmed in phase I clinical trials for GAP-134. These agents show an excellent promise for treatment of arrhythmias in patients with ischaemic cardiomyopathy.
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Affiliation(s)
- Elke De Vuyst
- Department of Basic Medical Sciences – Physiology group, Faculty of Medicine and Health Sciences, Ghent UniversityGhent, Belgium
| | - Kerstin Boengler
- Institut für Pathophysiologie, Zentrum für Innere Medizin, Universitätsklinikum EssenEssen, Germany
| | - Gudrun Antoons
- Department for Experimental Cardiology, O & N1, K.U.LeuvenLeuven, Belgium
| | - Karin R Sipido
- Department for Experimental Cardiology, O & N1, K.U.LeuvenLeuven, Belgium
| | - Rainer Schulz
- Institut für Physiologie, Justus-Liebig Universität GießenGießen, Germany
| | - Luc Leybaert
- Department of Basic Medical Sciences – Physiology group, Faculty of Medicine and Health Sciences, Ghent UniversityGhent, Belgium
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10
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Axelsen LN, Haugan K, Stahlhut M, Kjølbye AL, Hennan JK, Holstein-Rathlou NH, Petersen JS, Nielsen MS. Increasing Gap Junctional Coupling: A Tool for Dissecting the Role of Gap Junctions. J Membr Biol 2007; 216:23-35. [PMID: 17568971 DOI: 10.1007/s00232-007-9026-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2007] [Accepted: 04/04/2007] [Indexed: 11/30/2022]
Abstract
Much of our current knowledge about the physiological and pathophysiological role of gap junctions is based on experiments where coupling has been reduced by either chemical agents or genetic modification. This has brought evidence that gap junctions are important in many physiological processes. In a number of cases, gap junctions have been implicated in the initiation and progress of disease, and experimental uncoupling has been used to investigate the exact role of coupling. The inverse approach, i.e., to increase coupling, has become possible in recent years and represents a new way of testing the role of gap junctions. The aim of this review is to summarize the current knowledge obtained with agents that selectively increase gap junctional intercellular coupling. Two approaches will be reviewed: increasing coupling by the use of antiarrhythmic peptide and its synthetic analogs and by interfering with the gating of gap junctional channels.
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Min B, Kluger J, Kalus JS, Guertin D, McBride BF, White CM. The impact of catecholamines in patients with or without beta-blockers on the ventricular fibrillation cycle length and ventricular fibrillation cycle length variability. Ann Noninvasive Electrocardiol 2005; 10:305-11. [PMID: 16029381 PMCID: PMC6932532 DOI: 10.1111/j.1542-474x.2005.00631.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
OBJECTIVES To evaluate the impact of epinephrine, norepinephrine, or placebo on the ventricular fibrillation cycle length (VFCL) and the variability of VFCL (cvVFCL) measurements in implantable cardioverter defibrillator (ICD) patients with or without beta-blockers. METHODS Forty-three patients scheduled for their 6-week post-ICD placement noninvasive electrophysiologic study were included in the study at the Arrhythmia Procedure Laboratory at Hartford Hospital, Hartford, CT. This randomized, double-blind, placebo-controlled evaluation was approved by the Hartford Hospital Institutional Review Board. RESULTS After 2 seconds of continuous VF, 7 consecutive VFCLs were measured from the ICD device recording printout using a 0.5 mm scale ruler under magnification at baseline and after the infusion of catecholamines (epinephrine or norepinephrine at 2 mcg/min) or matching placebo at steady state. The average VFCL and the cvVFCL were determined for each study phase. Subgroup analysis based on chronic beta-blocker use was performed. No between-group differences were noted for epinephrine, norepinephrine, or placebo group for baseline (P=0.538) or postinfusion VFCL (P=0.749) or for baseline (P=0.561) or postinfusion cvVFCL (P=0.623) Regardless of catecholamine group randomization, longer pre- and postinfusion VFCL were noted in those receiving beta-blockers (P=0.157, P=0.019) but no differences in cvVFCL were noted (P=0.216, P=0.474) versus those without beta-blockers, respectively. CONCLUSION Moderately dosed epinephrine or norepinephrine does not affect either VFCL or the variability of VFCL after short duration of ventricular fibrillation. Chronic cardioselective beta-blockade prolongs VFCL without any impact on coefficient of variation of VFCL.
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Affiliation(s)
- Bokyung Min
- Divisions of Drug Information and Cardiology, Hartford Hospital, Hartford, CT and the University of Connecticut School of Pharmacy and Medicine, Storrs and Farmington, CT
| | - Jeffrey Kluger
- Divisions of Drug Information and Cardiology, Hartford Hospital, Hartford, CT and the University of Connecticut School of Pharmacy and Medicine, Storrs and Farmington, CT
| | - James S. Kalus
- Divisions of Drug Information and Cardiology, Hartford Hospital, Hartford, CT and the University of Connecticut School of Pharmacy and Medicine, Storrs and Farmington, CT
| | - Danette Guertin
- Divisions of Drug Information and Cardiology, Hartford Hospital, Hartford, CT and the University of Connecticut School of Pharmacy and Medicine, Storrs and Farmington, CT
| | - Brian F. McBride
- Divisions of Drug Information and Cardiology, Hartford Hospital, Hartford, CT and the University of Connecticut School of Pharmacy and Medicine, Storrs and Farmington, CT
| | - C. Michael White
- Divisions of Drug Information and Cardiology, Hartford Hospital, Hartford, CT and the University of Connecticut School of Pharmacy and Medicine, Storrs and Farmington, CT
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Abstract
INTRODUCTION Lidocaine is known to increase the defibrillation threshold (DFT) of monophasic shocks (MS) and have no effect on DFT of biphasic shocks (BS). The aim of this study was to enhance our understanding of the mechanisms of vulnerability and defibrillation through the investigation of this difference. METHODS AND RESULTS We studied the effect of 15 microM lidocaine on shock-induced vulnerability using fluorescent imaging of Langendorff-perfused rabbit hearts. Vulnerability was assessed as vulnerable window with shock strengths of 15 to 150 V and vulnerable period (VP) with shock delivery phase of 0% to 100% of action potential duration (% APD). With MS, lidocaine caused a significant increase in both the upper limit of vulnerability (ULV, 71 +/- 17 V vs 120 +/- 1.5 V, P < 0.01) and upper limit of VP (91 +/- 8.0% APD vs 110 +/- 4.2% APD, P < 0.01). With BS, lidocaine had no effect on ULV (40 +/- 3.4 V vs 45 +/- 4.5 V) and did not increase the upper limit of VP (78 +/- 8.9% APD vs 96 +/- 12% APD, P < 0.01). Lidocaine caused reduction of the conduction velocity during pacing (0.58 +/- 0.08 m/s vs 0.44 +/- 0.05 m/s, P < 0.01), shock-induced break excitation (0.82 +/- 0.17 m/s vs 0.30 +/- 0.07 m/s, P < 0.01), and postshock reentry (0.34 +/- 0.07 m/s vs 0.19 +/- 0.08 m/s, P < 0.01). Lidocaine had no effect on shock-induced virtual electrode polarization. CONCLUSION Lidocaine increased MS ULV due to slowing of shock-induced break-excitation wavefronts, which resulted in enhanced probability of survival of virtual electrode induced phase singularity. Lidocaine had no effect on BS ULV because no break excitation was induced by BS. Reduction of conduction velocity by lidocaine resulted in increased dispersion of repolarization and led to upper limit of VP increase for both MS and BS.
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Affiliation(s)
- Li Li
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio 44106-7207, USA
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13
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Keener JP, Cytrynbaum E. The effect of spatial scale of resistive inhomogeneity on defibrillation of cardiac tissue. J Theor Biol 2003; 223:233-48. [PMID: 12814605 DOI: 10.1016/s0022-5193(03)00089-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Defibrillation of cardiac tissue can be viewed in the context of dynamical systems theory as the attempt to move a dynamical system from the basin of attraction of one attractor (fibrillation) to another (the uniform rest state) by applying a stimulus whose form is physically constrained. Here we give an introduction to the physical mechanism of cardiac defibrillation from this dynamical perspective and examine the role of resistive inhomogeneity on defibrillation efficacy. Using numerical simulations with rotating waves on a one-dimensional periodic ring, we study the role of the spatial scale of resistive inhomogeneity on defibrillation. For a rotating wave on a periodic ring there are three stable attractors, namely the uniform rest state, a wave traveling clockwise and a wave traveling counterclockwise. As a result, the application of a stimulus has the potential for three different outcomes, namely elimination of the wave, phase resetting of the wave, and reversal of the wave. The results presented here show that with resistive inhomogeneities of large spatial scale, all three of these transitions are possible with large amplitude shocks, so that the probability of defibrillation is bounded well below one, independent of stimulus amplitude. On the other hand, resistive inhomogeneities of small spatial scale produce a defibrillation threshold that is qualitatively consistent with that found experimentally, namely the probability of defibrillation success is an increasing function that approaches one for large enough stimulus amplitude. Extending these results to higher dimensions, we describe conditions for successful defibrillation of functional reentry with large scale spatial inhomogeneity, but find that elimination of anatomical reentry is quite difficult. With small spatial scale inhomogeneity, there are no similar restrictions.
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Affiliation(s)
- James P Keener
- Department of Mathematics, University of Utah, 155 South 1400 East, Salt Lake City, UT 84112, USA.
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Sims JJ, Schoff KL, Loeb JM, Wiegert NA. Regional gap junction inhibition increases defibrillation thresholds. Am J Physiol Heart Circ Physiol 2003; 285:H10-6. [PMID: 12623782 DOI: 10.1152/ajpheart.01074.2002] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
It is clear that ischemia inhibits successful defibrillation by altering regional electro-physiology. However, the exact mechanisms are unclear. This study investigated whether regional gap junction inhibition increases biphasic shock defibrillation thresholds (DFT). Sixteen swine were instrumented with a mid-left anterior descending (LAD) perfusion catheter for regional infusion of 0.5 mM/h heptanol (n = 8) or saline (n = 8). DFT values and effective refractory periods (ERP) at five myocardial sites were determined. Regional conduction velocity (CV) was determined in an LAD drug-perfused and nondrug-perfused region in an additional seven swine. Regional heptanol infusion increased 50% DFT values by 33% (P = 0.01) and slowed CV by 42-59% (P < 0.01) but did not affect ERP. Regional heptanol also increased CV dispersion by approximately 270% (P < 0.05) but did not change ERP dispersion. Regional placebo did not alter any of these parameters. Furthermore, regional heptanol infusion induced spontaneous ventricular fibrillation in eight of eight animals. Increasing spatial conduction velocity dispersion by impairing regional gap junction conductance increased DFT values. Dispersion in conduction velocity slowing during regional ischemia may be an important determinant of defibrillation efficacy.
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Affiliation(s)
- J Jason Sims
- School of Pharmacy, University of Wisconsin, Madison, WI 53705, USA.
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