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Amoni M, Dries E, Ingelaere S, Vermoortele D, Roderick HL, Claus P, Willems R, Sipido KR. Ventricular Arrhythmias in Ischemic Cardiomyopathy-New Avenues for Mechanism-Guided Treatment. Cells 2021; 10:2629. [PMID: 34685609 PMCID: PMC8534043 DOI: 10.3390/cells10102629] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 09/20/2021] [Accepted: 09/23/2021] [Indexed: 12/13/2022] Open
Abstract
Ischemic heart disease is the most common cause of lethal ventricular arrhythmias and sudden cardiac death (SCD). In patients who are at high risk after myocardial infarction, implantable cardioverter defibrillators are the most effective treatment to reduce incidence of SCD and ablation therapy can be effective for ventricular arrhythmias with identifiable culprit lesions. Yet, these approaches are not always successful and come with a considerable cost, while pharmacological management is often poor and ineffective, and occasionally proarrhythmic. Advances in mechanistic insights of arrhythmias and technological innovation have led to improved interventional approaches that are being evaluated clinically, yet pharmacological advancement has remained behind. We review the mechanistic basis for current management and provide a perspective for gaining new insights that centre on the complex tissue architecture of the arrhythmogenic infarct and border zone with surviving cardiac myocytes as the source of triggers and central players in re-entry circuits. Identification of the arrhythmia critical sites and characterisation of the molecular signature unique to these sites can open avenues for targeted therapy and reduce off-target effects that have hampered systemic pharmacotherapy. Such advances are in line with precision medicine and a patient-tailored therapy.
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Affiliation(s)
- Matthew Amoni
- Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, 3000 Leuven, Belgium; (M.A.); (E.D.); (S.I.); (H.L.R.); (R.W.)
- Division of Cardiology, University Hospitals Leuven, 3000 Leuven, Belgium
- Department of Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town 7935, South Africa
| | - Eef Dries
- Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, 3000 Leuven, Belgium; (M.A.); (E.D.); (S.I.); (H.L.R.); (R.W.)
| | - Sebastian Ingelaere
- Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, 3000 Leuven, Belgium; (M.A.); (E.D.); (S.I.); (H.L.R.); (R.W.)
- Division of Cardiology, University Hospitals Leuven, 3000 Leuven, Belgium
| | - Dylan Vermoortele
- Imaging and Cardiovascular Dynamics, Department of Cardiovascular Sciences, KU Leuven, 3000 Leuven, Belgium; (D.V.); (P.C.)
| | - H. Llewelyn Roderick
- Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, 3000 Leuven, Belgium; (M.A.); (E.D.); (S.I.); (H.L.R.); (R.W.)
| | - Piet Claus
- Imaging and Cardiovascular Dynamics, Department of Cardiovascular Sciences, KU Leuven, 3000 Leuven, Belgium; (D.V.); (P.C.)
| | - Rik Willems
- Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, 3000 Leuven, Belgium; (M.A.); (E.D.); (S.I.); (H.L.R.); (R.W.)
- Division of Cardiology, University Hospitals Leuven, 3000 Leuven, Belgium
| | - Karin R. Sipido
- Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, 3000 Leuven, Belgium; (M.A.); (E.D.); (S.I.); (H.L.R.); (R.W.)
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Takahashi M, Yokoshiki H, Mitsuyama H, Watanabe M, Temma T, Kamada R, Hagiwara H, Takahashi Y, Anzai T. SK channel blockade prevents hypoxia-induced ventricular arrhythmias through inhibition of Ca 2+/voltage uncoupling in hypertrophied hearts. Am J Physiol Heart Circ Physiol 2021; 320:H1456-H1469. [PMID: 33635168 DOI: 10.1152/ajpheart.00777.2020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Accepted: 02/17/2021] [Indexed: 11/22/2022]
Abstract
Ventricular arrhythmia (VA) is the major cause of death in patients with left ventricular (LV) hypertrophy and/or acute ischemia. We hypothesized that apamin, a blocker of small-conductance Ca2+-activated K+ (SK) channels, alters Ca2+ handling and exhibits anti-arrhythmic effects in ventricular myocardium. Spontaneous hypertensive rats were used as a model of LV hypertrophy. A dual optical mapping of membrane potential (Vm) and intracellular calcium (Cai) was performed during global hypoxia (GH) on the Langendorff perfusion system. The majority of pacing-induced VAs during GH were initiated by triggered activities. Pretreatment of apamin (100 nmol/L) significantly inhibited the VA inducibility. Compared with SK channel blockers (apamin and NS8593), non-SK channel blockers (glibenclamide and 4-AP) did not exhibit anti-arrhythmic effects. Apamin prevented not only action potential duration (APD80) shortening (-18.7 [95% confidence interval, -35.2 to -6.05] ms vs. -2.75 [95% CI, -10.45 to 12.65] ms, P = 0.04) but also calcium transient duration (CaTD80) prolongation (14.52 [95% CI, 8.8-20.35] ms vs. 3.85 [95% CI, -3.3 to 12.1] ms, P < 0.01), thereby reducing CaTD80 - APD80, which denotes "Cai/Vm uncoupling" (33.22 [95% CI, 22-48.4] ms vs. 6.6 [95% CI, 0-14.85] ms, P < 0.01). The reduction of Cai/Vm uncoupling was attributable to less prolonged Ca2+ decay constant and suppression of diastolic Cai increase by apamin. The inhibition of VA inducibility and changes in APs/CaTs parameters caused by apamin was negated by the addition of ouabain, an inhibitor of Na+/K+ pump. Apamin attenuates APD shortening, Ca2+ handling abnormalities, and Cai/Vm uncoupling, leading to inhibition of VA occurrence in hypoxic hypertrophied hearts.NEW & NOTEWORTHY We demonstrated that hypoxia-induced ventricular arrhythmias were mainly initiated by Ca2+-loaded triggered activities in hypertrophied hearts. The blockades of small-conductance Ca2+-activated K+ channels, especially "apamin," showed anti-arrhythmic effects by alleviation of not only action potential duration shortening but also Ca2+ handling abnormalities, most notably the "Ca2+/voltage uncoupling."
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Affiliation(s)
- Masayuki Takahashi
- Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine, Sapporo, Japan
- Department of Cardiovascular Medicine, National Hospital Organization Hokkaido Medical Center, Sapporo, Japan
| | - Hisashi Yokoshiki
- Department of Cardiovascular Medicine, Sapporo City General Hospital, Sapporo, Japan
| | - Hirofumi Mitsuyama
- Department of Cardiovascular Medicine, Hokkaido Ohno Memorial Hospital, Sapporo, Japan
| | - Masaya Watanabe
- Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Taro Temma
- Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Rui Kamada
- Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Hikaru Hagiwara
- Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Yumi Takahashi
- Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Toshihisa Anzai
- Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine, Sapporo, Japan
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Ford KL, Moorhouse EL, Bortolozzi M, Richards MA, Swietach P, Vaughan-Jones RD. Regional acidosis locally inhibits but remotely stimulates Ca2+ waves in ventricular myocytes. Cardiovasc Res 2018; 113:984-995. [PMID: 28339694 PMCID: PMC5852542 DOI: 10.1093/cvr/cvx033] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 02/17/2017] [Indexed: 11/30/2022] Open
Abstract
Aims Spontaneous Ca2+ waves in cardiomyocytes are potentially arrhythmogenic. A
powerful controller of Ca2+ waves is the cytoplasmic H+
concentration ([H+]i), which fluctuates spatially and temporally
in conditions such as myocardial ischaemia/reperfusion. H+-control of
Ca2+ waves is poorly understood. We have therefore investigated how
[H+]i co-ordinates their initiation and frequency. Methods and results Spontaneous Ca2+ waves were imaged (fluo-3) in rat isolated ventricular
myocytes, subjected to modest Ca2+-overload. Whole-cell intracellular
acidosis (induced by acetate-superfusion) stimulated wave frequency. Pharmacologically
blocking sarcolemmal Na+/H+ exchange (NHE1) prevented this
stimulation, unveiling inhibition by H+. Acidosis also increased
Ca2+ wave velocity. Restricting acidosis to one end of a myocyte, using a
microfluidic device, inhibited Ca2+ waves in the acidic zone (consistent with
ryanodine receptor inhibition), but stimulated wave emergence elsewhere in the cell.
This remote stimulation was absent when NHE1 was selectively inhibited in the acidic
zone. Remote stimulation depended on a locally evoked, NHE1-driven rise of
[Na+]i that spread rapidly downstream. Conclusion Acidosis influences Ca2+ waves via inhibitory Hi+ and stimulatory Nai+ signals (the latter facilitating intracellular
Ca2+-loading through modulation of sarcolemmal
Na+/Ca2+ exchange activity). During spatial
[H+]i-heterogeneity, Hi+-inhibition dominates in acidic regions, while rapid
Nai+ diffusion stimulates waves in downstream, non-acidic
regions. Local acidosis thus simultaneously inhibits and stimulates arrhythmogenic
Ca2+-signalling in the same myocyte. If the principle of remote
H+-stimulation of Ca2+ waves also applies in multicellular
myocardium, it raises the possibility of electrical disturbances being driven remotely
by adjacent ischaemic areas, which are known to be intensely acidic.
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Affiliation(s)
- Kerrie L Ford
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, Oxford, OX1 3PT, UK
| | - Emma L Moorhouse
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, Oxford, OX1 3PT, UK
| | - Mario Bortolozzi
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, Oxford, OX1 3PT, UK.,Department of Physics and Astronomy "G. Galilei", University of Padua, 35121 Padua, Italy
| | - Mark A Richards
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, Oxford, OX1 3PT, UK
| | - Pawel Swietach
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, Oxford, OX1 3PT, UK
| | - Richard D Vaughan-Jones
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, Oxford, OX1 3PT, UK
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Wit AL. Basic Electrophysiologic Mechanisms of Sudden Cardiac Death Caused by Acute Myocardial Ischemia and Infarction. Card Electrophysiol Clin 2017; 9:525-536. [PMID: 29173399 DOI: 10.1016/j.ccep.2017.07.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Sudden cardiac death caused by acute ischemia results from electrophysiologic changes in myocardium deprived of its blood supply. These changes include a reduction in resting potential and phase 0 depolarization and an increase in intercellular resistivity that slow conduction, cause conduction block, and lead to reentrant excitation and ventricular fibrillation. Reperfusion of a coronary artery after a short period of occlusion leads to similar changes.
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Affiliation(s)
- Andrew L Wit
- Department of Pharmacology, College of Physicians and Surgeons of Columbia University, 630 West 168(th) Street, New York, NY 10032, USA.
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5
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Matsuyama TA, Tanaka H, Ishibashi-Ueda H, Takamatsu T. Spatiotemporally Non-Uniform Ca 2+ Dynamics of Cardiac Purkinje Fibers in Mouse Myocardial Infarct. J Histochem Cytochem 2017; 65:655-667. [PMID: 28903013 DOI: 10.1369/0022155417730280] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Surviving Purkinje fibers in myocardial infarct are regarded as an important substrate in arrhythmogenesis. However, poorly understood are functional properties of Purkinje fibers in the infarcted heart. We sought to visualize intracellular Ca2+ ([Ca2+]i) dynamics of Purkinje fiber networks in the mouse myocardial infarct. Using 3- to 4-day-old or 7- to 9-day-old infarcted hearts after the left coronary-artery ligation corresponding, respectively, to acute or healing phase, we conducted rapid fluo4-fluorescence imaging on the endocardial surface of the left ventricular septum by macro-zoom fluorescence microscopy and rapid-scanning confocal microscopy. In contrast with the intact heart, where uniform Ca2+ transients propagated rapidly, the infarcted heart exhibited slow, non-uniform impulse propagations. On confocal microscopy, Purkinje fibers in the peri-infarct zone exhibited non-uniform [Ca2+]i dynamics: beat-to-beat alternans of the Ca2+ transient amplitude in and among the individual fibers, whereas the intact fibers exhibited uniform Ca2+ transients. Such non-uniform [Ca2+]i dynamics were more conspicuous in the acute infarcted hearts than in the healing ones. In accordance with [Ca2+]i dynamics, fixed fluo4-loaded heart preparations exhibited definitive connexin-40 plaques in the peri-infarct Purkinje fibers, whereas the subjacent myocardium presented coagulative necrosis and granulation tissues, respectively. The surviving Purkinje fibers in the peri-infarct zone exhibited non-uniform [Ca2+]i dynamics, which may lead to arrhythmogenesis.
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Affiliation(s)
- Taka-Aki Matsuyama
- Department of Pathology and Cell Regulation, Kyoto Prefectural University of Medicine Graduate School of Medical Science, Kyoto, Japan
| | - Hideo Tanaka
- Department of Pathology and Cell Regulation, Kyoto Prefectural University of Medicine Graduate School of Medical Science, Kyoto, Japan
| | - Hatsue Ishibashi-Ueda
- Department of Pathology, National Cerebral and Cardiovascular Center, Suita, Osaka, Japan
| | - Tetsuro Takamatsu
- Department of Medical Photonics, Kyoto Prefectural University of Medicine, Kyoto, Japan
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Pharmacological blockade of small conductance Ca 2+-activated K + channels by ICA reduces arrhythmic load in rats with acute myocardial infarction. Pflugers Arch 2017; 469:739-750. [PMID: 28285409 DOI: 10.1007/s00424-017-1962-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Revised: 02/07/2017] [Accepted: 02/20/2017] [Indexed: 01/02/2023]
Abstract
Acute myocardial infarction (AMI) with development of ventricular fibrillation (VF) is a common cause of sudden cardiac death (SCD). At present, no pharmacological treatment has successfully been able to prevent VF in the acute stage of AMI. This study investigates the antiarrhythmic effect of inhibiting small conductance Ca2+-activated K+ (SK) channels using the pore blocker N-(pyridin-2-yl)-4-(pyridin-2-yl)thiazol-2-amine (ICA) in AMI rats. Acute coronary ligation was performed in 26 anesthetized rats, and ECG, monophasic action potentials (MAPs), and ventricular effective refractory period (vERP) were recorded. Rats were randomized into four groups: (i) 3 mg/kg i.v. ICA with AMI (AMI-ICA-group, n = 9), (ii) vehicle with AMI (AMI-vehicle-group, n = 9), (iii) vehicle with sham operation (sham-vehicle-group, n = 8), and (iv) 3 mg/kg i.v. ICA with sham operation (sham-ICA-group, n = 6). At the end of experiments, hearts were stained for the non-perfused area at risk (AAR). AMI resulted in the development of ventricular tachycardia (VT) in all AMI-vehicle and AMI-ICA rats; however, ICA significantly decreased VT duration. VF occurred in 44% of AMI-vehicle rats but not in AMI-ICA rats. Monophasic action potential duration at 80% repolarization (MAPD80) in the ischemic area decreased rapidly in both AMI-vehicle and AMI-ICA rats. However, 5 min after occlusion, MAPD80 returned to baseline in AMI-ICA rats but not in AMI-vehicle rats. The vERP was prolonged in the AMI-ICA group compared to AMI-vehicle after ligation. AAR was similar between the AMI-vehicle group and the AMI-ICA group. In rats with AMI, ICA reduces the burden of arrhythmia.
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Mizukami K, Yokoshiki H, Mitsuyama H, Watanabe M, Tenma T, Takada S, Tsutsui H. Small-conductance Ca2+-activated K+ current is upregulated via the phosphorylation of CaMKII in cardiac hypertrophy from spontaneously hypertensive rats. Am J Physiol Heart Circ Physiol 2015; 309:H1066-74. [DOI: 10.1152/ajpheart.00825.2014] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Accepted: 08/12/2015] [Indexed: 01/09/2023]
Abstract
Left ventricular hypertrophy is associated with an increased risk of ventricular arrhythmias. However, the underlying molecular basis is poorly understood. It has been reported that small-conductance Ca2+-activated K+ (SK) channels are involved in the pathogenesis of ventricular arrhythmias in heart failure. The present study aimed to test the hypothesis that SK channel activity is increased via the Ca2+/calmodulin-dependent protein kinase II (CaMKII)-dependent pathway in hypertensive cardiac hypertrophy. Normotensive Wistar-Kyoto (WKY) rats and spontaneous hypertensive rats (SHRs) were used. Whole cell membrane currents were recorded in isolated ventricular myocytes by the patch-clamp method, and apamin-sensitive K+ current ( IKAS), which is inhibited by apamin (100 nM), an SK channel blocker, was evaluated. IKAS at 40 mV was present in SHRs, whereas it was hardly detectable in WKY rats (0.579 ± 0.046 vs. 0.022 ± 0.062 pA/pF, both n = 6, P < 0.05). IKAS was almost completely abolished by 1 μM KN-93, a CaMKII inhibitor, in SHRs. Optical recordings of left ventricular anterior wall action potentials revealed that apamin prolonged the late phase of repolarization only in SHRs. Western blot analysis of SK channel protein isoforms demonstrated that SK2 was significantly increased in SHRs compared with WKY rats (SK2/GAPDH: 0.66 ± 0.07 vs. 0.40 ± 0.02, both n = 6, P < 0.05), whereas SK1 and SK3 did not differ between groups. In addition, autophosphorylated CaMKII was significantly increased in SHRs (phosphorylated CaMKII/GAPDH: 0.80 ± 0.06 vs. 0.58 ± 0.06, both n = 6, P < 0.05) despite a comparable total amount of CaMKII between groups. In conclusion, SK channels are upregulated via the enhanced activation of CaMKII in cardiac hypertrophy in SHRs.
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Affiliation(s)
- Kazuya Mizukami
- Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Hisashi Yokoshiki
- Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Hirofumi Mitsuyama
- Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Masaya Watanabe
- Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Taro Tenma
- Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Shingo Takada
- Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Hiroyuki Tsutsui
- Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine, Sapporo, Japan
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Crocini C, Coppini R, Ferrantini C, Pavone FS, Sacconi L. Functional cardiac imaging by random access microscopy. Front Physiol 2014; 5:403. [PMID: 25368580 PMCID: PMC4202699 DOI: 10.3389/fphys.2014.00403] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Accepted: 09/29/2014] [Indexed: 11/22/2022] Open
Abstract
Advances in the development of voltage sensitive dyes and Ca2+ sensors in combination with innovative microscopy techniques allowed researchers to perform functional measurements with an unprecedented spatial and temporal resolution. At the moment, one of the shortcomings of available technologies is their incapability of imaging multiple fast phenomena while controlling the biological determinants involved. In the near future, ultrafast deflectors can be used to rapidly scan laser beams across the sample, performing optical measurements of action potential and Ca2+ release from multiple sites within cardiac cells and tissues. The same scanning modality could also be used to control local Ca2+ release and membrane electrical activity by activation of caged compounds and light-gated ion channels. With this approach, local Ca2+ or voltage perturbations could be induced, simulating arrhythmogenic events, and their impact on physiological cell activity could be explored. The development of this optical methodology will provide fundamental insights in cardiac disease, boosting new therapeutic strategies, and, more generally, it will represent a new approach for the investigation of the physiology of excitable cells.
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Affiliation(s)
- Claudia Crocini
- European Laboratory for Non-Linear Spectroscopy (LENS) Florence, Italy
| | - Raffaele Coppini
- Division of Pharmacology, Department "NeuroFarBa," University of Florence Florence, Italy
| | - Cecilia Ferrantini
- Division of Physiology, Department of Experimental and Clinical Medicine, University of Florence Florence, Italy
| | - Francesco S Pavone
- European Laboratory for Non-Linear Spectroscopy (LENS) Florence, Italy ; Department of Physics and Astronomy, University of Florence Sesto Fiorentino, Italy ; National Research Council, National Institute of Optics Florence, Italy
| | - Leonardo Sacconi
- European Laboratory for Non-Linear Spectroscopy (LENS) Florence, Italy ; National Research Council, National Institute of Optics Florence, Italy
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CHOU CHUNGCHUAN, WEN MINGSHIEN, LEE HUILING, CHANG POCHENG, WO HUNGTA, YEH SANJOU, WU DELON. Dantrolene Suppresses Ventricular Ectopy and Arrhythmogenicity with Acute Myocardial Infarction in a Langendorff-Perfused Pacing-Induced Heart Failure Rabbit Model. J Cardiovasc Electrophysiol 2013; 25:431-439. [DOI: 10.1111/jce.12320] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Revised: 10/09/2013] [Accepted: 10/23/2013] [Indexed: 11/28/2022]
Affiliation(s)
- CHUNG-CHUAN CHOU
- Division of Cardiology; Department of Internal Medicine; Chang Gung Memorial Hospital; Linko Taipei Taiwan
- Chang Gung University College of Medicine; Taoyuan Taiwan
| | - MING-SHIEN WEN
- Division of Cardiology; Department of Internal Medicine; Chang Gung Memorial Hospital; Linko Taipei Taiwan
- Chang Gung University College of Medicine; Taoyuan Taiwan
| | - HUI-LING LEE
- Department of Anesthesia; Chang Gung Memorial Hospital; Taipei Taiwan
| | - PO-CHENG CHANG
- Division of Cardiology; Department of Internal Medicine; Chang Gung Memorial Hospital; Linko Taipei Taiwan
| | - HUNG-TA WO
- Division of Cardiology; Department of Internal Medicine; Chang Gung Memorial Hospital; Linko Taipei Taiwan
| | - SAN-JOU YEH
- Division of Cardiology; Department of Internal Medicine; Chang Gung Memorial Hospital; Linko Taipei Taiwan
- Chang Gung University College of Medicine; Taoyuan Taiwan
| | - DELON WU
- Division of Cardiology; Department of Internal Medicine; Chang Gung Memorial Hospital; Linko Taipei Taiwan
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Bidirectional ventricular tachycardia in a patient with acute myocardial infarction and aortic stenosis. Int J Cardiol 2013; 162:e41-2. [PMID: 22658352 DOI: 10.1016/j.ijcard.2012.05.061] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2012] [Accepted: 05/11/2012] [Indexed: 11/27/2022]
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11
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Gui L, Bao Z, Jia Y, Qin X, (Jack) Cheng Z, Zhu J, Chen QH. Ventricular tachyarrhythmias in rats with acute myocardial infarction involves activation of small-conductance Ca2+-activated K+ channels. Am J Physiol Heart Circ Physiol 2013; 304:H118-30. [PMID: 23086994 DOI: 10.1152/ajpheart.00820.2011] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In vitro experiments have shown that the upregulation of small-conductance Ca2+-activated K+ (SK) channels in ventricular epicardial myocytes is responsible for spontaneous ventricular fibrillation (VF) in failing ventricles. However, the role of SK channels in regulating VF has not yet been described in in vivo acute myocardial infarction (AMI) animals. The present study determined the role of SK channels in regulating spontaneous sustained ventricular tachycardia (SVT) and VF, the inducibility of ventricular tachyarrhythmias, and the effect of inhibition of SK channels on spontaneous SVT/VF and electrical ventricular instability in AMI rats. AMI was induced by ligation of the left anterior descending coronary artery in anesthetized rats. Spontaneous SVT/VF was analyzed, and programmed electrical stimulation was performed to evaluate the inducibility of ventricular tachyarrhythmias, ventricular effective refractory period (VERP), and VF threshold (VFT). In AMI, the duration and episodes of spontaneous SVT/VF were increased, and the inducibility of ventricular tachyarrhythmias was elevated. Pretreatment in the AMI group with the SK channel blocker apamin or UCL-1684 significantly reduced SVT/VF and inducibility of ventricular tachyarrhythmias ( P < 0.05). Various doses of apamin (7.5, 22.5, 37.5, and 75.0 μg/kg iv) inhibited SVT/VF and the inducibility of ventricular tachyarrhythmias in a dose-dependent manner. Notably, no effects were observed in sham-operated controls. Additionally, VERP was shortened in AMI animals. Pretreatment in AMI animals with the SK channel blocker significantly prolonged VERP ( P < 0.05). No effects were observed in sham-operated controls. Furthermore, VFT was reduced in AMI animals, and block of SK channels increased VFT in AMI animals, but, again, this was without effect in sham-operated controls. Finally, the monophasic action potential duration at 90% repolarization (MAPD90) was examined in the myocardial infarcted (MI) and nonmyocardial infarcted areas (NMI) of the left ventricular epicardium. Electrophysiology recordings showed that MAPD90 in the MI area was shortened in AMI animals, and pretreatment with SK channel blocker apamin or UCL-1684 significantly prolonged MAPD90 ( P < 0.05) in the MI area but was without effect in the NMI area or in sham-operated controls. We conclude that the activation of SK channels may underlie the mechanisms of spontaneous SVT/VF and suseptibility to ventricular tachyarrhythmias in AMI. Inhibition of SK channels normalized the shortening of MAPD90 in the MI area, which may contribute to the inhibitory effect on spontaneous SVT/VF and inducibility of ventricular tachyarrhythmias in AMI.
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Affiliation(s)
- Le Gui
- Department of Cardiology, Affiliated Hospital of Nantong University, Nantong, Jiangsu, People's Republic of China
- Department of Kinesiology and Integrative Physiology, Michigan Technological University, Houghton, Michigan
| | - Zhiwei Bao
- Department of Cardiology, Affiliated Hospital of Nantong University, Nantong, Jiangsu, People's Republic of China
| | - Yinyu Jia
- Department of Cardiology, Affiliated Hospital of Nantong University, Nantong, Jiangsu, People's Republic of China
| | - Xiaotong Qin
- Department of Cardiology, Affiliated Hospital of Nantong University, Nantong, Jiangsu, People's Republic of China
| | - Zixi (Jack) Cheng
- Biomolecular Science Center, Burnett School of Biomedical Sciences College of Medicine, University of Central Florida, Orlando, Florida; and
| | - Jianhua Zhu
- Department of Cardiology, Affiliated Hospital of Nantong University, Nantong, Jiangsu, People's Republic of China
| | - Qing-Hui Chen
- Department of Kinesiology and Integrative Physiology, Michigan Technological University, Houghton, Michigan
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Tveito A, Lines GT, Edwards AG, Maleckar MM, Michailova A, Hake J, McCulloch A. Slow Calcium-Depolarization-Calcium waves may initiate fast local depolarization waves in ventricular tissue. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2012; 110:295-304. [PMID: 22841534 DOI: 10.1016/j.pbiomolbio.2012.07.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2012] [Accepted: 07/16/2012] [Indexed: 10/28/2022]
Abstract
Intercellular calcium waves in cardiac myocytes are a well-recognized, if incompletely understood, phenomenon. In a variety of preparations, investigators have reported multi-cellular calcium waves or triggered propagated contractions, but the mechanisms of propagation and pathological importance of these events remain unclear. Here, we review existing experimental data and present a computational approach to investigate the mechanisms of multi-cellular calcium wave propagation. Over the past 50 years, the standard modeling paradigm for excitable cardiac tissue has seen increasingly detailed models of the dynamics of individual cells coupled in tissue solely by intercellular and interstitial current flow. Although very successful, this modeling regime has been unable to capture two important phenomena: 1) the slow intercellular calcium waves observed experimentally, and 2) how intercellular calcium events resulting in delayed after depolarizations at the cellular level could overcome a source-sink mismatch to initiate depolarization waves in tissue. In this paper, we introduce a mathematical model with subcellular spatial resolution, in which we allow both inter- and intracellular current flow and calcium diffusion. In simulations of coupled cells employing this model, we observe: a) slow inter-cellular calcium waves propagating at about 0.1 mm/s, b) faster Calcium-Depolarization-Calcium (CDC) waves, traveling at about 1 mm/s, and c) CDC-waves that can set off fast depolarization-waves (50 cm/s) in tissue with varying gap-junction conductivity.
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Affiliation(s)
- Aslak Tveito
- Center for Biomedical Computing, Simula Research Laboratory, Norway
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Nuñez IP, Fantinelli J, Arbeláez LFG, Mosca SM. Mitochondrial KATP channels participate in the limitation of infarct size by cariporide. Naunyn Schmiedebergs Arch Pharmacol 2011; 383:563-71. [DOI: 10.1007/s00210-011-0632-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2010] [Accepted: 03/27/2011] [Indexed: 12/25/2022]
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Vaughan-Jones RD, Spitzer KW, Swietach P. Intracellular pH regulation in heart. J Mol Cell Cardiol 2008; 46:318-31. [PMID: 19041875 DOI: 10.1016/j.yjmcc.2008.10.024] [Citation(s) in RCA: 216] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2008] [Accepted: 10/11/2008] [Indexed: 12/14/2022]
Abstract
Intracellular pH (pHi) is an important modulator of cardiac excitation and contraction, and a potent trigger of electrical arrhythmia. This review outlines the intracellular and membrane mechanisms that control pHi in the cardiac myocyte. We consider the kinetic regulation of sarcolemmal H+, OH- and HCO3- transporters by pH, and by receptor-coupled intracellular signalling systems. We also consider how activity of these pHi effector proteins is coordinated spatially in the myocardium by intracellular mobile buffer shuttles, gap junctional channels and carbonic anhydrase enzymes. Finally, we review the impact of pHi regulatory proteins on intracellular Ca2+ signalling, and their participation in clinical disorders such as myocardial ischaemia, maladaptive hypertrophy and heart failure. Such multiple effects emphasise the fundamental role that pHi regulation plays in the heart.
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Affiliation(s)
- Richard D Vaughan-Jones
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, Oxford, Parks Road, OX1 3PT, UK.
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Abstract
Life-threatening ventricular tachyarrhythmias are common clinical complications in ischemic heart diseases, especially infarcted heart. Although electrophysiological mechanisms have been extensively clarified for the genesis of arrhythmias in myocardial infarct, arrhythmogenic substrates in the infarct that eventually lead to electrical derangements are not fully understood. This review focuses on the intracellular calcium ion (Ca2+) dynamics and connexin43 (Cx43) gap junctions that play pivotal roles in excitation/contraction processes and intercellular communication, respectively, in heart muscle cells. Recent development of Ca2+-sensitive fluorescent dyes as well as microscopy imaging techniques has contributed substantially to a more precise understanding of spatiotemporal aspects in the intra- and inter-cellular dynamics of Ca2+ in cardiomyocytes. Ca2+ waves, heterogeneous wave-like elevations of the intracellular Ca2+ concentrations ([Ca2+](i)) that develop under [Ca2+](i)-overloaded conditions of the injured myocardium, play an essential role in arrhythmias, especially in triggered arrhythmias. Alteration of Cx43-mediated electrical coupling, that is, gap junction remodeling that arises at myocyte-myocyte and myocyte-myofibroblast interfaces, would also be an important substrate for arrhythmias, especially re-entrant tachyarrhythmias. Clarification of these substrates would provide not only deeper insights into the upstream events of life-threatening tachyarrhythmias in the infarcted heart but also bases for new therapeutic strategies for cardiovascular diseases.
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Affiliation(s)
- Tetsuro Takamatsu
- Department of Pathology and Cell Regulation, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, Kawaramachi-Hirokoji, Kamigyo-Ku, Kyoto 602-8566, Japan.
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Klauke N, Smith G, Cooper JM. Microfluidic systems to examine intercellular coupling of pairs of cardiac myocytes. LAB ON A CHIP 2007; 7:731-9. [PMID: 17538715 DOI: 10.1039/b706175g] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
In this paper we describe a microfluidic environment that enables us to explore cell-to-cell signalling between longitudinally linked primary heart cells. We have chosen to use pairs (or doublets) of cardiac myocyte as a model system, not only because of the importance of cell-cell signalling in the study of heart disease but also because the single cardiomyocytes are both mechanically and electrically active and their synchronous activation due to the intercellular coupling within the doublet can be readily monitored on optical and electrical recordings. Such doublets have specialised intercellular contact structures in the form of the intercalated discs, comprising the adhesive junction (fascia adherens and macula adherens or desmosome) and the connecting junction (known as gap junction). The latter structure enables adjacent heart cells to share ions, second messengers and small metabolites (<1 kDa) between them and thus provides the structural basis for the synchronous (syncytical) behaviour of connected cardiomyocytes. Using the unique environment provided by the microfluidic system, described in this paper, we explore the local ionic conditions that enable the propagation of Ca(2+) waves between two heart cells. We observe that the ability of intracellular Ca(2+) waves to traverse the intercalated discs is dependent on the relative concentrations of diastolic Ca(2+) in the two adjacent cells. These experiments rely upon our ability to independently control both the electrical stimulation of each of the cells (using integrated microelectrodes) and to rapidly change (or switch) the local concentrations of ions and drugs in the extracellular buffer within the microfluidic channel (using a nanopipetting system). Using this platform, it is also possible to make simultaneous optical recordings (including fluorescence and cell contraction) to explore the effect of drugs on one or both cells, within the doublet.
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Affiliation(s)
- Norbert Klauke
- Department of Electronics, University of Glasgow, Glasgow, UK G12 8LT
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De Falco M, De Luca A. Meeting report on the 12th International Congress of Histochemistry and Cytochemistry (ICHC). J Cell Physiol 2005; 204:407-11. [PMID: 15895396 PMCID: PMC7166837 DOI: 10.1002/jcp.20418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The International Congress of Histochemistry and Cytochemistry (ICHC) promoted in San Diego La Jolla (CA, USA), the 12th meeting where researchers of all over the world presented their work and the most innovative methods in histochemical disciplines. A summary of the last meeting is reported. © 2005 Wiley‐Liss, Inc.
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Affiliation(s)
- Maria De Falco
- Department of Evolutionary and Comparative Biology, University of Naples “Federico II”, Naples, Italy
| | - Antonio De Luca
- Department of Medicine and Public Health, Section of Clinical Anatomy, Second University of Naples, Naples, Italy
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Swietach P, Leem CH, Spitzer KW, Vaughan-Jones RD. Experimental generation and computational modeling of intracellular pH gradients in cardiac myocytes. Biophys J 2005; 88:3018-37. [PMID: 15653720 PMCID: PMC1305395 DOI: 10.1529/biophysj.104.051391] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
It is often assumed that pH(i) is spatially uniform within cells. A double-barreled microperfusion system was used to apply solutions of weak acid (acetic acid, CO(2)) or base (ammonia) to localized regions of an isolated ventricular myocyte (guinea pig). A stable, longitudinal pH(i) gradient (up to 1 pH(i) unit) was observed (using confocal imaging of SNARF-1 fluorescence). Changing the fractional exposure of the cell to weak acid/base altered the gradient, as did changing the concentration and type of weak acid/base applied. A diffusion-reaction computational model accurately simulated this behavior of pH(i). The model assumes that H(i)(+) movement occurs via diffusive shuttling on mobile buffers, with little free H(+) diffusion. The average diffusion constant for mobile buffer was estimated as 33 x 10(-7) cm(2)/s, consistent with an apparent H(i)(+) diffusion coefficient, D(H)(app), of 14.4 x 10(-7) cm(2)/s (at pH(i) 7.07), a value two orders of magnitude lower than for H(+) ions in water but similar to that estimated recently from local acid injection via a cell-attached glass micropipette. We conclude that, because H(i)(+) mobility is so low, an extracellular concentration gradient of permeant weak acid readily induces pH(i) nonuniformity. Similar concentration gradients for weak acid (e.g., CO(2)) occur across border zones during regional myocardial ischemia, raising the possibility of steep pH(i) gradients within the heart under some pathophysiological conditions.
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Affiliation(s)
- Pawel Swietach
- Burdon Sanderson Cardiac Science Centre, University Laboratory of Physiology, Oxford OX1 3PT, UK
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Tanaka H, Takamatsu T. Spatiotemporal Visualization of Intracellular Ca2+ in Living Heart Muscle Cells Viewed by Confocal Laser Scanning Microscopy. Acta Histochem Cytochem 2003. [DOI: 10.1267/ahc.36.193] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- Hideo Tanaka
- Department of Pathology and Cell Regulation, Kyoto Prefectural University of Medicine
| | - Tetsuro Takamatsu
- Department of Pathology and Cell Regulation, Kyoto Prefectural University of Medicine
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