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Ferreira G, Cardozo R, Sastre S, Costa C, Santander A, Chavarría L, Guizzo V, Puglisi J, Nicolson GL. Bacterial toxins and heart function: heat-labile Escherichia coli enterotoxin B promotes changes in cardiac function with possible relevance for sudden cardiac death. Biophys Rev 2023; 15:447-473. [PMID: 37681088 PMCID: PMC10480140 DOI: 10.1007/s12551-023-01100-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Accepted: 07/11/2023] [Indexed: 09/09/2023] Open
Abstract
Bacterial toxins can cause cardiomyopathy, though it is not its most common cause. Some bacterial toxins can form pores in the membrane of cardiomyocytes, while others can bind to membrane receptors. Enterotoxigenic E. coli can secrete enterotoxins, including heat-resistant (ST) or labile (LT) enterotoxins. LT is an AB5-type toxin that can bind to specific cell receptors and disrupt essential host functions, causing several common conditions, such as certain diarrhea. The pentameric B subunit of LT, without A subunit (LTB), binds specifically to certain plasma membrane ganglioside receptors, found in lipid rafts of cardiomyocytes. Isolated guinea pig hearts and cardiomyocytes were exposed to different concentrations of purified LTB. In isolated hearts, mechanical and electrical alternans and an increment of heart rate variability, with an IC50 of ~0.2 μg/ml LTB, were observed. In isolated cardiomyocytes, LTB promoted significant decreases in the amplitude and the duration of action potentials. Na+ currents were inhibited whereas L-type Ca2+ currents were augmented at their peak and their fast inactivation was promoted. Delayed rectifier K+ currents decreased. Measurements of basal Ca2+ or Ca2+ release events in cells exposed to LTB suggest that LTB impairs Ca2+ homeostasis. Impaired calcium homeostasis is linked to sudden cardiac death. The results are consistent with the recent view that the B subunit is not merely a carrier of the A subunit, having a role explaining sudden cardiac death in children (SIDS) infected with enterotoxigenic E. coli, explaining several epidemiological findings that establish a strong relationship between SIDS and ETEC E. coli. Supplementary Information The online version contains supplementary material available at 10.1007/s12551-023-01100-6.
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Affiliation(s)
- Gonzalo Ferreira
- Ion Channels, Biological Membranes and Cell Signaling Laboratory, Dept. Of Biophysics, Facultad de Medicina, Universidad de la Republica, Gral Flores 2125, 11800 Montevideo, CP Uruguay
| | - Romina Cardozo
- Ion Channels, Biological Membranes and Cell Signaling Laboratory, Dept. Of Biophysics, Facultad de Medicina, Universidad de la Republica, Gral Flores 2125, 11800 Montevideo, CP Uruguay
| | - Santiago Sastre
- Ion Channels, Biological Membranes and Cell Signaling Laboratory, Dept. Of Biophysics and Centro de Investigaciones Biomédicas (CeInBio), Facultad de Medicina, Universidad de la Republica, Gral Flores 2125, 11800 Montevideo, CP Uruguay
| | - Carlos Costa
- Ion Channels, Biological Membranes and Cell Signaling Laboratory, Dept. Of Biophysics, Facultad de Medicina, Universidad de la Republica, Gral Flores 2125, 11800 Montevideo, CP Uruguay
| | - Axel Santander
- Ion Channels, Biological Membranes and Cell Signaling Laboratory, Dept. Of Biophysics, Facultad de Medicina, Universidad de la Republica, Gral Flores 2125, 11800 Montevideo, CP Uruguay
| | - Luisina Chavarría
- Ion Channels, Biological Membranes and Cell Signaling Laboratory, Dept. Of Biophysics, Facultad de Medicina, Universidad de la Republica, Gral Flores 2125, 11800 Montevideo, CP Uruguay
| | - Valentina Guizzo
- Ion Channels, Biological Membranes and Cell Signaling Laboratory, Dept. Of Biophysics, Facultad de Medicina, Universidad de la Republica, Gral Flores 2125, 11800 Montevideo, CP Uruguay
| | - José Puglisi
- College of Medicine, California North State University, 9700 West Taron Drive, Elk Grove, CA 95757 USA
| | - G. L. Nicolson
- Institute for Molecular Medicine, Beach, Huntington, CA USA
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Vila BDCP, Vanhoni MS, Sousa MG. QT interval instability and variability in dogs with naturally-occurring hypercortisolism. Vet Res Commun 2023; 47:121-130. [PMID: 35575953 DOI: 10.1007/s11259-022-09936-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 05/04/2022] [Indexed: 01/27/2023]
Abstract
Hypercortisolism is one of the most common endocrine diseases in dogs. In humans, it is clearly associated with a higher risk of cardiovascular events, but studies in dogs are scarce. To investigate the arrhythmogenic risk of dogs with naturally-occurring hypercortisolism (NOHC), indices of variability and instability of the QT interval were retrospectively studied in 38 dogs with NOHC and prospectively studied in 12 healthy dogs: variance (QTv), total instability (TI), short-term (STI) and long-term (LTI), and mean (QTm). Except for QTm, all parameters studied were higher in the NOHC group than in the control group. In addition, STI and QTv showed moderate positive correlation with left ventricle wall thickness. The NOHC group was subdivided according to cortisol suppression pattern in the low-dose dexamethasone suppression test. All electrocardiographic indices of partial and absent suppression patterns were numerically higher than healthy dogs. QTv and TI were lower in the control group than in both NOHC subgroups. LTI and STI were lower in the CG than in the group with the partial suppression pattern. There was no statistical difference between sex groups in any of the electrocardiographic parameters studied. This result might indicate that the etiology of NOHC, and its consequent influence on hypothalamus-pituitary-adrenal axis could interfere on the heterogeneity of ventricular repolarization parameters in different ways, especially in the short-term and the long-term stability; however further studies are necessary to understand the role of cortisol on electrical instability in dogs.
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Affiliation(s)
- Beatriz de Carvalho Pato Vila
- Laboratory of Comparative Cardiology, Department of Veterinary Medicine, Federal University of Paraná (UFPR), Rua dos Funcionários, 1540, Curitiba, PR, 80035-050, Brazil.
| | - Marcela Sigolo Vanhoni
- Laboratory of Comparative Cardiology, Department of Veterinary Medicine, Federal University of Paraná (UFPR), Rua dos Funcionários, 1540, Curitiba, PR, 80035-050, Brazil
| | - Marlos Gonçalves Sousa
- Laboratory of Comparative Cardiology, Department of Veterinary Medicine, Federal University of Paraná (UFPR), Rua dos Funcionários, 1540, Curitiba, PR, 80035-050, Brazil
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Limprasutr V, Pirintr P, Kijtawornrat A, Hamlin RL. An increasing electromechanical window is a predictive marker of ventricular fibrillation in anesthetized rabbit with ischemic heart. Exp Anim 2017; 67:175-183. [PMID: 29162767 PMCID: PMC5955749 DOI: 10.1538/expanim.17-0100] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The QTc interval is widely used in Safety Pharmacological studies to predict arrhythmia
risk, and the electromechanical window (EMW) and short-term variability of QT intervals
(STVQT) have been studied as new biomarkers for drug-induced Torsades de
Pointes (TdP). However, the use of EMW and STVQT to predict ventricular
fibrillation (VF) has not been elucidated. This study aimed to evaluate EMW and
STVQT to predict VF in anesthetized rabbit model of VF. VF was induced by
ligation of the left anterior descending and a descending branch of the left circumflex
coronary arteries in a sample population of rabbits (n=18). VF was developed 55.6%
(10/18). In rabbit with VF, the EMW was significantly higher than in rabbits without VF
(96.3 ± 15.6 ms and 49.5 ± 5.6 ms, respectively, P<0.05).
STVQT had significantly increased before the onset of VF in rabbits that
experienced VF, but not in rabbits that did not experience VF (11.7 ± 1.8 ms and 3.7 ± 0.4
ms, respectively, P<0.05). The EMW and STVQT had better
predictive power for VF with higher sensitivity and specificity than the QTc measure. The
result suggested that the increasing of EMW, as well as the elevation of STVQT,
can potentially be used as biomarkers for predicting of VF.
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Affiliation(s)
- Vudhiporn Limprasutr
- Department of Physiology, Faculty of Veterinary Science, Chulalongkorn University, 39 Henri Dunant Road, Wang Mai, Pathumwan, Bangkok 10330, Thailand
| | - Prapawadee Pirintr
- Department of Physiology, Faculty of Veterinary Science, Chulalongkorn University, 39 Henri Dunant Road, Wang Mai, Pathumwan, Bangkok 10330, Thailand.,Department of Veterinary Biosciences and Veterinary Public Health, Faculty of Veterinary Medicine, Chiang Mai University, 155 Tumbon Mae Hiae, Muang, Chiang Mai 50100, Thailand
| | - Anusak Kijtawornrat
- Department of Physiology, Faculty of Veterinary Science, Chulalongkorn University, 39 Henri Dunant Road, Wang Mai, Pathumwan, Bangkok 10330, Thailand.,Research clusters: research study and testing of drug's effect related to cardiovascular system in laboratory animals, Chulalongkorn University, 39 Henri Dunant Road, Wang Mai, Pathumwan, Bangkok 10330, Thailand
| | - Robert L Hamlin
- QTest Labs, LLC. 6456 Fiesta Drive, Columbus, Ohio 43235, USA
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Nánási PP, Magyar J, Varró A, Ördög B. Beat-to-beat variability of cardiac action potential duration: underlying mechanism and clinical implications. Can J Physiol Pharmacol 2017; 95:1230-1235. [PMID: 28746810 DOI: 10.1139/cjpp-2016-0597] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Beat-to-beat variability of cardiac action potential duration (short-term variability, SV) is a common feature of various cardiac preparations, including the human heart. Although it is believed to be one of the best arrhythmia predictors, the underlying mechanisms are not fully understood at present. The magnitude of SV is basically determined by the intensity of cell-to-cell coupling in multicellular preparations and by the duration of the action potential (APD). To compensate for the APD-dependent nature of SV, the concept of relative SV (RSV) has been introduced by normalizing the changes of SV to the concomitant changes in APD. RSV is reduced by ICa, IKr, and IKs while increased by INa, suggesting that ion currents involved in the negative feedback regulation of APD tend to keep RSV at a low level. RSV is also influenced by intracellular calcium concentration and tissue redox potential. The clinical implications of APD variability is discussed in detail.
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Affiliation(s)
- Péter P Nánási
- a Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.,b Department of Dental Physiology and Pharmacology, Faculty of Dentistry, University of Debrecen, Debrecen, Hungary
| | - János Magyar
- a Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - András Varró
- c Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - Balázs Ördög
- c Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
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Yarmohmmadi F, Rahimi N, Faghir-Ghanesefat H, Javadian N, Abdollahi A, Pasalar P, Jazayeri F, Ejtemaeemehr S, Dehpour AR. Protective effects of agmatine on doxorubicin-induced chronic cardiotoxicity in rat. Eur J Pharmacol 2017; 796:39-44. [DOI: 10.1016/j.ejphar.2016.12.022] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2016] [Revised: 12/12/2016] [Accepted: 12/14/2016] [Indexed: 12/28/2022]
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Kui P, Orosz S, Takács H, Sarusi A, Csík N, Rárosi F, Csekő C, Varró A, Papp JG, Forster T, Farkas AS, Farkas A. New in vitro model for proarrhythmia safety screening: IKs inhibition potentiates the QTc prolonging effect of IKr inhibitors in isolated guinea pig hearts. J Pharmacol Toxicol Methods 2016; 80:26-34. [DOI: 10.1016/j.vascn.2016.04.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Revised: 04/01/2016] [Accepted: 04/04/2016] [Indexed: 01/25/2023]
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Baumert M, Porta A, Vos MA, Malik M, Couderc JP, Laguna P, Piccirillo G, Smith GL, Tereshchenko LG, Volders PGA. QT interval variability in body surface ECG: measurement, physiological basis, and clinical value: position statement and consensus guidance endorsed by the European Heart Rhythm Association jointly with the ESC Working Group on Cardiac Cellular Electrophysiology. Europace 2016; 18:925-44. [PMID: 26823389 PMCID: PMC4905605 DOI: 10.1093/europace/euv405] [Citation(s) in RCA: 140] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Accepted: 11/05/2015] [Indexed: 12/20/2022] Open
Abstract
This consensus guideline discusses the electrocardiographic phenomenon of beat-to-beat QT interval variability (QTV) on surface electrocardiograms. The text covers measurement principles, physiological basis, and clinical value of QTV. Technical considerations include QT interval measurement and the relation between QTV and heart rate variability. Research frontiers of QTV include understanding of QTV physiology, systematic evaluation of the link between QTV and direct measures of neural activity, modelling of the QTV dependence on the variability of other physiological variables, distinction between QTV and general T wave shape variability, and assessing of the QTV utility for guiding therapy. Increased QTV appears to be a risk marker of arrhythmic and cardiovascular death. It remains to be established whether it can guide therapy alone or in combination with other risk factors. QT interval variability has a possible role in non-invasive assessment of tonic sympathetic activity.
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Affiliation(s)
- Mathias Baumert
- School of Electrical and Electronic Engineering, The University of Adelaide, Adelaide, SA, Australia
| | - Alberto Porta
- Department of Biomedical Sciences for Health, University of Milan, Milan, Italy Department of Cardiothoracic, Vascular Anesthesia and Intensive Care, IRCCS Policlinico San Donato, Milan, Italy
| | - Marc A Vos
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Marek Malik
- St Paul's Cardiac Electrophysiology, University of London, and National Heart and Lung Institute, Imperial College, Dovehouse Street, London SW3 6LY, UK
| | - Jean-Philippe Couderc
- Heart Research Follow-Up Program, University of Rochester Medical Center, Rochester, NY, USA
| | - Pablo Laguna
- Zaragoza University and CIBER-BBN, Zaragoza, Spain
| | - Gianfranco Piccirillo
- Dipartimento di Scienze Cardiovascolari, Respiratorie, Nefrologiche, Anestesiologiche e Geriatriche, Università 'La Sapienza' Rome, Rome, Italy
| | - Godfrey L Smith
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, UK
| | - Larisa G Tereshchenko
- Oregon Health and Science University, Knight Cardiovascular Institute, Portland, OR, USA
| | - Paul G A Volders
- Department of Cardiology, Cardiovascular Research Institute Maastricht, Maastricht University Medical Centre, Maastricht, The Netherlands
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Baczkó I, Jost N, Virág L, Bősze Z, Varró A. Rabbit models as tools for preclinical cardiac electrophysiological safety testing: Importance of repolarization reserve. Prog Biophys Mol Biol 2016; 121:157-68. [PMID: 27208697 DOI: 10.1016/j.pbiomolbio.2016.05.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Accepted: 05/01/2016] [Indexed: 01/26/2023]
Abstract
It is essential to more reliably assess the pro-arrhythmic liability of compounds in development. Current guidelines for pre-clinical and clinical testing of drug candidates advocate the use of healthy animals/tissues and healthy individuals and focus on the test compound's ability to block the hERG current and prolong cardiac ventricular repolarization. Also, pre-clinical safety tests utilize several species commonly used in cardiac electrophysiological studies. In this review, important species differences in cardiac ventricular repolarizing ion currents are considered, followed by the discussion on electrical remodeling associated with chronic cardiovascular diseases that leads to altered ion channel and transporter expression and densities in pathological settings. We argue that the choice of species strongly influences experimental outcome and extrapolation of results to human clinical settings. We suggest that based on cardiac cellular electrophysiology, the rabbit is a useful species for pharmacological pro-arrhythmic investigations. In addition to healthy animals and tissues, the use of animal models (e.g. those with impaired repolarization reserve) is suggested that more closely resemble subsets of patients exhibiting increased vulnerability towards the development of ventricular arrhythmias and sudden cardiac death.
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Affiliation(s)
- István Baczkó
- Department of Pharmacology & Pharmacotherapy, University of Szeged, Dóm tér 12., 6720 Szeged, Hungary.
| | - Norbert Jost
- Department of Pharmacology & Pharmacotherapy, University of Szeged, Dóm tér 12., 6720 Szeged, Hungary; MTA-SZTE Research Group of Cardiovascular Pharmacology, Hungarian Academy of Sciences, Dóm tér 12., 6720 Szeged, Hungary
| | - László Virág
- Department of Pharmacology & Pharmacotherapy, University of Szeged, Dóm tér 12., 6720 Szeged, Hungary
| | - Zsuzsanna Bősze
- Rabbit Genome and Biomodel Group, NARIC-Agricultural Biotechnology Institute, 2100 Gödöllő, Hungary
| | - András Varró
- Department of Pharmacology & Pharmacotherapy, University of Szeged, Dóm tér 12., 6720 Szeged, Hungary; MTA-SZTE Research Group of Cardiovascular Pharmacology, Hungarian Academy of Sciences, Dóm tér 12., 6720 Szeged, Hungary
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Orosz S, Sarusi A, Csík N, Papp JG, Varró A, Farkas S, Forster T, Farkas AS, Farkas A. Assessment of efficacy of proarrhythmia biomarkers in isolated rabbit hearts with attenuated repolarization reserve. J Cardiovasc Pharmacol 2014; 64:266-76. [PMID: 24887684 DOI: 10.1097/FJC.0000000000000116] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Isolated hearts with reduced repolarization reserve would be suitable for assessing the proarrhythmic liability of drugs. However, it is not known which proarrhythmia biomarkers indicate the increased susceptibility to torsades de pointes arrhythmia (TdP) in such experimental setting. Thus, we estimated the efficacy of proarrhythmia biomarkers in isolated hearts with attenuated repolarization reserve. Langendorff-perfused rabbit hearts were used. Repolarization reserve was reduced by concomitant inhibition of the rapid (IKr) and slow (IKs) delayed rectifier potassium currents by dofetilide and HMR-1556, respectively. Rate corrected QT (QTc) interval and beat-to-beat variability of the QT interval measured in sinus rhythm or irrespective of rhythm even during arrhythmias (sinus and absolute QT variability, respectively) were tested. QTc failed to predict increased proarrhythmic risk. Sinus QT variability indicated proarrhythmic liability when low concentration of dofetilide was used. However, when arrhythmias compromised sinus variability measurement during coperfusion of catecholamines and elevated concentration of dofetilide, only absolute QT variability indicated increased proarrhythmic risk. Absolute QT variability parameters seem to be the most practical and sensitive biomarkers of proarrhythmic liability in rabbit hearts with reduced repolarization reserve. Absolute QT variability parameters could serve as surrogates for torsades de pointes in drug-safety investigations in isolated rabbit hearts with attenuated repolarization reserve.
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Ozturk C, Balta S, Demirkol S, Unlu M, Celik T, Iyisoy A. The QT measurements after biventricular pacing, is it reliable? J Saudi Heart Assoc 2014; 26:231-2. [DOI: 10.1016/j.jsha.2014.02.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Accepted: 02/18/2014] [Indexed: 11/24/2022] Open
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