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Sharma AK, Singh S, Bhat M, Gill K, Zaid M, Kumar S, Shakya A, Tantray J, Jose D, Gupta R, Yangzom T, Sharma RK, Sahu SK, Rathore G, Chandolia P, Singh M, Mishra A, Raj S, Gupta A, Agarwal M, Kifayat S, Gupta A, Gupta P, Vashist A, Vaibhav P, Kathuria N, Yadav V, Singh RP, Garg A. New drug discovery of cardiac anti-arrhythmic drugs: insights in animal models. Sci Rep 2023; 13:16420. [PMID: 37775650 PMCID: PMC10541452 DOI: 10.1038/s41598-023-41942-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Accepted: 09/04/2023] [Indexed: 10/01/2023] Open
Abstract
Cardiac rhythm regulated by micro-macroscopic structures of heart. Pacemaker abnormalities or disruptions in electrical conduction, lead to arrhythmic disorders may be benign, typical, threatening, ultimately fatal, occurs in clinical practice, patients on digitalis, anaesthesia or acute myocardial infarction. Both traditional and genetic animal models are: In-vitro: Isolated ventricular Myocytes, Guinea pig papillary muscles, Patch-Clamp Experiments, Porcine Atrial Myocytes, Guinea pig ventricular myocytes, Guinea pig papillary muscle: action potential and refractory period, Langendorff technique, Arrhythmia by acetylcholine or potassium. Acquired arrhythmia disorders: Transverse Aortic Constriction, Myocardial Ischemia, Complete Heart Block and AV Node Ablation, Chronic Tachypacing, Inflammation, Metabolic and Drug-Induced Arrhythmia. In-Vivo: Chemically induced arrhythmia: Aconitine antagonism, Digoxin-induced arrhythmia, Strophanthin/ouabain-induced arrhythmia, Adrenaline-induced arrhythmia, and Calcium-induced arrhythmia. Electrically induced arrhythmia: Ventricular fibrillation electrical threshold, Arrhythmia through programmed electrical stimulation, sudden coronary death in dogs, Exercise ventricular fibrillation. Genetic Arrhythmia: Channelopathies, Calcium Release Deficiency Syndrome, Long QT Syndrome, Short QT Syndrome, Brugada Syndrome. Genetic with Structural Heart Disease: Arrhythmogenic Right Ventricular Cardiomyopathy/Dysplasia, Dilated Cardiomyopathy, Hypertrophic Cardiomyopathy, Atrial Fibrillation, Sick Sinus Syndrome, Atrioventricular Block, Preexcitation Syndrome. Arrhythmia in Pluripotent Stem Cell Cardiomyocytes. Conclusion: Both traditional and genetic, experimental models of cardiac arrhythmias' characteristics and significance help in development of new antiarrhythmic drugs.
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Affiliation(s)
- Ashish Kumar Sharma
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India.
| | - Shivam Singh
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Mehvish Bhat
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Kartik Gill
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Mohammad Zaid
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Sachin Kumar
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Anjali Shakya
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Junaid Tantray
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Divyamol Jose
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Rashmi Gupta
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Tsering Yangzom
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Rajesh Kumar Sharma
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | | | - Gulshan Rathore
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Priyanka Chandolia
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Mithilesh Singh
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Anurag Mishra
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Shobhit Raj
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Archita Gupta
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Mohit Agarwal
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Sumaiya Kifayat
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Anamika Gupta
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Prashant Gupta
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Ankit Vashist
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Parth Vaibhav
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Nancy Kathuria
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Vipin Yadav
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Ravindra Pal Singh
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Arun Garg
- MVN University, Palwal, Haryana, India
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2
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Li X, Tian G, Xu L, Sun L, Tao R, Zhang S, Cong Z, Deng F, Chen J, Yu Y, Du W, Zhao H. Wenxin Keli for the Treatment of Arrhythmia-Systems Pharmacology and In Vivo Pharmacological Assessment. Front Pharmacol 2021; 12:704622. [PMID: 34512338 PMCID: PMC8426352 DOI: 10.3389/fphar.2021.704622] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Accepted: 07/21/2021] [Indexed: 12/13/2022] Open
Abstract
This study employed a systems pharmacology approach to identify the active compounds and action mechanisms of Wenxin Keli for arrhythmia treatment. Sixty-eight components identified in vivo and in vitro by UPLC/Q-TOF-MS were considered the potential active components of Wenxin Keli. Network pharmacology further revealed 33 key targets and 75 KEGG pathways as possible pathways and targets involved in WK-mediated treatment, with the CaMKII/CNCA1C/Ca2+ pathway being the most significantly affected. This finding was validated using an AC-induced rat arrhythmias model. Pretreatment with Wenxin Keli reduced the malignant arrhythmias and shortened RR, PR, and the QT interval. Wenxin Keli exerted some antiarrhythmic effects by inhibiting p-CaMKII and intracellular Ca2+ transients and overexpressing CNCA1C. Thus, suppressing SR Ca2+ release and maintaining intracellular Ca2+ balance may be the primary mechanism of Wenxin Keli against arrhythmia. In view of the significance of CaMKII and NCX identified in this experiment, we suggest that CaMKII and NCX are essential targets for treating arrhythmias.
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Affiliation(s)
- Xiaofeng Li
- Department of Cardiology, The Second Affiliated Hospital of Tianjin University of TCM, Tianjin, China
| | - Gang Tian
- Department of Cardiology, Teda International Cardiovascular Hospital, Tianjin, China
| | - Liang Xu
- School of Pharmacy, Tianjin Medical University, Tianjin, China.,Tianjin Medical College, Tianjin, China
| | - Lili Sun
- Department of TCM, Tianjin University of TCM, Tianjin, China
| | - Rui Tao
- Department of TCM, Tianjin University of TCM, Tianjin, China
| | - Shaoqiang Zhang
- Department of Cardiology, The Second Affiliated Hospital of Tianjin University of TCM, Tianjin, China
| | - Zidong Cong
- Department of Cardiology, The Second Affiliated Hospital of Tianjin University of TCM, Tianjin, China
| | - Fangjun Deng
- Department of TCM, Tianjin University of TCM, Tianjin, China
| | - Jinhong Chen
- Department of TCM, Tianjin University of TCM, Tianjin, China
| | - Yang Yu
- Department of Aeronautics and Astronautics, Tsinghua University, Beijing, China
| | - Wuxun Du
- Department of Cardiology, The Second Affiliated Hospital of Tianjin University of TCM, Tianjin, China
| | - Hucheng Zhao
- Department of Aeronautics and Astronautics, Tsinghua University, Beijing, China
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3
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Njegic A, Wilson C, Cartwright EJ. Targeting Ca 2 + Handling Proteins for the Treatment of Heart Failure and Arrhythmias. Front Physiol 2020; 11:1068. [PMID: 33013458 PMCID: PMC7498719 DOI: 10.3389/fphys.2020.01068] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Accepted: 08/04/2020] [Indexed: 12/18/2022] Open
Abstract
Diseases of the heart, such as heart failure and cardiac arrhythmias, are a growing socio-economic burden. Calcium (Ca2+) dysregulation is key hallmark of the failing myocardium and has long been touted as a potential therapeutic target in the treatment of a variety of cardiovascular diseases (CVD). In the heart, Ca2+ is essential for maintaining normal cardiac function through the generation of the cardiac action potential and its involvement in excitation contraction coupling. As such, the proteins which regulate Ca2+ cycling and signaling play a vital role in maintaining Ca2+ homeostasis. Changes to the expression levels and function of Ca2+-channels, pumps and associated intracellular handling proteins contribute to altered Ca2+ homeostasis in CVD. The remodeling of Ca2+-handling proteins therefore results in impaired Ca2+ cycling, Ca2+ leak from the sarcoplasmic reticulum and reduced Ca2+ clearance, all of which contributes to increased intracellular Ca2+. Currently, approved treatments for targeting Ca2+ handling dysfunction in CVD are focused on Ca2+ channel blockers. However, whilst Ca2+ channel blockers have been successful in the treatment of some arrhythmic disorders, they are not universally prescribed to heart failure patients owing to their ability to depress cardiac function. Despite the progress in CVD treatments, there remains a clear need for novel therapeutic approaches which are able to reverse pathophysiology associated with heart failure and arrhythmias. Given that heart failure and cardiac arrhythmias are closely associated with altered Ca2+ homeostasis, this review will address the molecular changes to proteins associated with both Ca2+-handling and -signaling; their potential as novel therapeutic targets will be discussed in the context of pre-clinical and, where available, clinical data.
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Affiliation(s)
- Alexandra Njegic
- Division of Cardiovascular Sciences, The University of Manchester, Manchester, United Kingdom.,Centre for Tumour Biology, Barts Cancer Institute, Queen Mary University of London, London, United Kingdom
| | - Claire Wilson
- Division of Cardiovascular Sciences, The University of Manchester, Manchester, United Kingdom.,Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Elizabeth J Cartwright
- Division of Cardiovascular Sciences, The University of Manchester, Manchester, United Kingdom
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Driessen HE, Fontes MS, van Stuijvenberg L, Brans MA, Goumans MJ, Vos MA, van Veen TA. A combined CaMKII inhibition and mineralocorticoid receptor antagonism via eplerenone inhibits functional deterioration in chronic pressure overloaded mice. J Cell Mol Med 2020; 24:8417-8429. [PMID: 32573944 PMCID: PMC7412412 DOI: 10.1111/jcmm.15355] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 11/12/2019] [Accepted: 12/09/2019] [Indexed: 12/26/2022] Open
Abstract
In the diseased and remodelled heart, increased activity and expression of Ca2+/ calmodulin-dependent protein kinase II (CaMKII), an excess of fibrosis, and a decreased electrical coupling and cellular excitability leads to disturbed calcium homeostasis and tissue integrity. This subsequently leads to increased arrhythmia vulnerability and contractile dysfunction. Here, we investigated the combination of CaMKII inhibition (using genetically modified mice expressing the autocamtide-3-related-peptide (AC3I)) together with eplerenone treatment (AC3I-Epler) to prevent electrophysiological remodelling, fibrosis and subsequent functional deterioration in a mouse model of chronic pressure overload. We compared AC3I-Epler mice with mice only subjected to mineralocorticoid receptor (MR) antagonism (WT-Epler) and mice with only CaMKII inhibition (AC3I-No). Our data show that a combined CaMKII inhibition together with MR antagonism mitigates contractile deterioration as was manifested by a preservation of ejection fraction, fractional shortening, global longitudinal strain, peak strain and contractile synchronicity. Furthermore, patchy fibrosis formation was reduced, potentially via inhibition of pro-fibrotic TGF-β/SMAD3 signalling, which related to a better global contractile performance and a slightly depressed incidence of arrhythmias. Furthermore, the level of patchy fibrosis appeared significantly correlated to eplerenone dose. The addition of eplerenone to CaMKII inhibition potentiates the effects of CaMKII inhibition on pro-fibrotic pathways. As a result of the applied strategy, limiting patchy fibrosis adheres to a higher synchronicity of contraction and an overall better contractile performance which fits with a tempered arrhythmogenesis.
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Affiliation(s)
- Helen E Driessen
- Division of Heart & Lungs, Department of Medical Physiology, University Medical Centre Utrecht, Utrecht, The Netherlands
| | - Magda S Fontes
- Division of Heart & Lungs, Department of Medical Physiology, University Medical Centre Utrecht, Utrecht, The Netherlands
| | - Leonie van Stuijvenberg
- Division of Heart & Lungs, Department of Medical Physiology, University Medical Centre Utrecht, Utrecht, The Netherlands
| | - Maike A Brans
- Division of Heart & Lungs, Department of Medical Physiology, University Medical Centre Utrecht, Utrecht, The Netherlands
| | | | - Marc A Vos
- Division of Heart & Lungs, Department of Medical Physiology, University Medical Centre Utrecht, Utrecht, The Netherlands
| | - Toon A van Veen
- Division of Heart & Lungs, Department of Medical Physiology, University Medical Centre Utrecht, Utrecht, The Netherlands
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5
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Weiss JN, Qu Z, Shivkumar K. Electrophysiology of Hypokalemia and Hyperkalemia. Circ Arrhythm Electrophysiol 2019; 10:CIRCEP.116.004667. [PMID: 28314851 DOI: 10.1161/circep.116.004667] [Citation(s) in RCA: 179] [Impact Index Per Article: 35.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 02/06/2017] [Indexed: 12/26/2022]
Affiliation(s)
- James N Weiss
- From the UCLA Cardiovascular Research Laboratory and Cardiac Arrhythmia Center, Departments of Medicine (Cardiology) (J.N.W., Z.Q., K.S.), Physiology (J.N.W.), and Radiological Sciences (K.S.), David Geffen School of Medicine at UCLA, Los Angeles, CA.
| | - Zhilin Qu
- From the UCLA Cardiovascular Research Laboratory and Cardiac Arrhythmia Center, Departments of Medicine (Cardiology) (J.N.W., Z.Q., K.S.), Physiology (J.N.W.), and Radiological Sciences (K.S.), David Geffen School of Medicine at UCLA, Los Angeles, CA
| | - Kalyanam Shivkumar
- From the UCLA Cardiovascular Research Laboratory and Cardiac Arrhythmia Center, Departments of Medicine (Cardiology) (J.N.W., Z.Q., K.S.), Physiology (J.N.W.), and Radiological Sciences (K.S.), David Geffen School of Medicine at UCLA, Los Angeles, CA
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6
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McMillan B, Gavaghan DJ, Mirams GR. Early afterdepolarisation tendency as a simulated pro-arrhythmic risk indicator. Toxicol Res (Camb) 2017; 6:912-921. [PMID: 29456831 PMCID: PMC5779076 DOI: 10.1039/c7tx00141j] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 09/12/2017] [Indexed: 12/19/2022] Open
Abstract
Drug-induced Torsades de Pointes (TdP) arrhythmia is of major interest in predictive toxicology. Drugs which cause TdP block the hERG cardiac potassium channel. However, not all drugs that block hERG cause TdP. As such, further understanding of the mechanistic route to TdP is needed. Early afterdepolarisations (EADs) are a cell-level phenomenon in which the membrane of a cardiac cell depolarises a second time before repolarisation, and EADs are seen in hearts during TdP. Therefore, we propose a method of predicting TdP using induced EADs combined with multiple ion channel block in simulations using biophysically-based mathematical models of human ventricular cell electrophysiology. EADs were induced in cardiac action potential models using interventions based on diseases that are known to cause EADs, including: increasing the conduction of the L-type calcium channel, decreasing the conduction of the hERG channel, and shifting the inactivation curve of the fast sodium channel. The threshold of intervention that was required to cause an EAD was used to classify drugs into clinical risk categories. The metric that used L-type calcium induced EADs was the most accurate of the EAD metrics at classifying drugs into the correct risk categories, and increased in accuracy when combined with action potential duration measurements. The EAD metrics were all more accurate than hERG block alone, but not as predictive as simpler measures such as simulated action potential duration. This may be because different routes to EADs represent risk well for different patient subgroups, something that is difficult to assess at present.
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Affiliation(s)
- Beth McMillan
- Computational Biology , Dept. of Computer Science , University of Oxford , Oxford , OX1 3QD , UK . ; ; Tel: +44 (0)1865 273838
| | - David J Gavaghan
- Computational Biology , Dept. of Computer Science , University of Oxford , Oxford , OX1 3QD , UK . ; ; Tel: +44 (0)1865 273838
| | - Gary R Mirams
- Centre for Mathematical Biology , School of Mathematical Sciences , University of Nottingham , Nottingham , NG7 2RD , UK
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7
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Takanari H, Bourgonje VJA, Fontes MSC, Raaijmakers AJA, Driessen H, Jansen JA, van der Nagel R, Kok B, van Stuijvenberg L, Boulaksil M, Takemoto Y, Yamazaki M, Tsuji Y, Honjo H, Kamiya K, Kodama I, Anderson ME, van der Heyden MAG, van Rijen HVM, van Veen TAB, Vos MA. Calmodulin/CaMKII inhibition improves intercellular communication and impulse propagation in the heart and is antiarrhythmic under conditions when fibrosis is absent. Cardiovasc Res 2016; 111:410-21. [PMID: 27357638 PMCID: PMC4996261 DOI: 10.1093/cvr/cvw173] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Revised: 06/09/2016] [Accepted: 06/21/2016] [Indexed: 11/14/2022] Open
Abstract
AIM In healthy hearts, ventricular gap junctions are mainly composed by connexin43 (Cx43) and localize in the intercalated disc, enabling appropriate electrical coupling. In diseased hearts, Cx43 is heterogeneously down-regulated, whereas activity of calmodulin/calcium-calmodulin protein kinase II (CaM/CaMKII) signalling increases. It is unclear if CaM/CaMKII affects Cx43 expression/localization or impulse propagation. We analysed different models to assess this. METHODS AND RESULTS AC3-I mice with CaMKII genetically inhibited were subjected to pressure overload (16 weeks, TAC vs. sham). Optical and epicardial mapping was performed on Langendorff-perfused rabbit and AC3-I hearts, respectively. Cx43 subcellular distribution from rabbit/mouse ventricles was evaluated by immunoblot after Triton X-100-based fractionation. In mice with constitutively reduced CaMKII activity (AC3-I), conduction velocity (CV) was augmented (n = 11, P < 0.01 vs. WT); in AC3-I, CV was preserved after TAC, in contrast to a reduction seen in TAC-WT mice (-20%). Cx43 expression was preserved after TAC in AC3-I mice, though arrhythmias and fibrosis were still present. In rabbits, W7 (CaM inhibitor, 10 µM) increased CV (6-13%, n= 6, P< 0.05), while susceptibility to arrhythmias decreased. Immunoconfocal microscopy revealed enlarged Cx43 cluster sizes at intercalated discs of those hearts. Total Cx43 did not change by W7 (n= 4), whereas Triton X-100 insoluble Cx43 increased (+21%, n= 4, P< 0.01). Similar findings were obtained in AC3-I mouse hearts when compared with control, and in cultured dog cardiomyocytes. Functional implication was shown through increased intercellular coupling in cultured neonatal rat cardiomyocytes. CONCLUSION Both acute and chronic CaM/CaMKII inhibition improves conduction characteristics and enhances localization of Cx43 in the intercalated disc. In the absence of fibrosis, this reduced the susceptibility for arrhythmias.
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Affiliation(s)
- Hiroki Takanari
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, The Netherlands Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan Department of Pathophysiology, Oita University School of Medicine, Yufu, Japan
| | - Vincent J A Bourgonje
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Magda S C Fontes
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Antonia J A Raaijmakers
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Helen Driessen
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, The Netherlands
| | - John A Jansen
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Roel van der Nagel
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Bart Kok
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Leonie van Stuijvenberg
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Mohamed Boulaksil
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, The Netherlands Department of Cardiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Yoshio Takemoto
- Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
| | - Masatoshi Yamazaki
- Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
| | - Yukiomi Tsuji
- Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
| | - Haruo Honjo
- Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
| | - Kaichiro Kamiya
- Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
| | | | - Mark E Anderson
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MA, USA
| | - Marcel A G van der Heyden
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Harold V M van Rijen
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Toon A B van Veen
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Marc A Vos
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, The Netherlands
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8
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Thomas SHL, Behr ER. Pharmacological treatment of acquired QT prolongation and torsades de pointes. Br J Clin Pharmacol 2015; 81:420-7. [PMID: 26183037 DOI: 10.1111/bcp.12726] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Revised: 07/13/2015] [Accepted: 07/14/2015] [Indexed: 12/21/2022] Open
Abstract
Torsades de pointes (TdP) is a characteristic polymorphic ventricular arrhythmia associated with delayed ventricular repolarization as evidenced on the surface electrocardiogram by QT interval prolongation. It typically occurs in self-limiting bursts, causing dizziness and syncope, but may occasionally progress to ventricular fibrillation and sudden death. Acquired long QT syndromes are mainly caused by cardiac disease, electrolyte abnormalities or exposure to drugs that block rectifying potassium channels, especially IKr. Management of TdP or marked QT prolongation includes removal or correction of precipitants, including discontinuation of culprit drugs and institution of cardiac monitoring. Electrolyte abnormalities and hypoxia should be corrected, with potassium concentrations maintained in the high normal range. Immediate treatment of TdP is by intravenous administration of magnesium sulphate, terminating prolonged episodes using electrical cardioversion. In refractory cases of recurrent TdP, the arrhythmia can be suppressed by increasing the underlying heart rate using isoproterenol (isoprenaline) or transvenous pacing. Other interventions are rarely needed, but there are case reports of successful use of lidocaine or phenytoin. Anti-arrhythmic drugs that prolong ventricular repolarization should be avoided. Some episodes of TdP could be avoided by careful prescribing of QT prolonging drugs, including an individualized assessment of risks and benefits before use, performing baseline and periodic electrocardiograms and measurement of electrolytes, especially during acute illnesses, using the lowest effective dose for the shortest possible time and avoiding potential drug interactions. These steps are particularly important in those with underlying repolarization abnormalities and those who have previously experienced drug-induced TdP.
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Affiliation(s)
- Simon H L Thomas
- Medical Toxicology Centre, Wolfson Building, Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, NE2 4HH.,National Poisons Information Service Newcastle Unit, Newcastle Hospitals NHS Foundation Trust, Newcastle upon Tyne, NE1 4LP
| | - Elijah R Behr
- Cardiovascular Research Centre, St George's University of London, London, SW17 0RE, UK
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9
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Pezhouman A, Singh N, Song Z, Nivala M, Eskandari A, Cao H, Bapat A, Ko CY, Nguyen T, Qu Z, Karagueuzian HS, Weiss JN. Molecular Basis of Hypokalemia-Induced Ventricular Fibrillation. Circulation 2015; 132:1528-1537. [PMID: 26269574 DOI: 10.1161/circulationaha.115.016217] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 08/05/2015] [Indexed: 11/16/2022]
Abstract
BACKGROUND Hypokalemia is known to promote ventricular arrhythmias, especially in combination with class III antiarrhythmic drugs like dofetilide. Here, we evaluated the underlying molecular mechanisms. METHODS AND RESULTS Arrhythmias were recorded in isolated rabbit and rat hearts or patch-clamped ventricular myocytes exposed to hypokalemia (1.0-3.5 mmol/L) in the absence or presence of dofetilide (1 μmol/L). Spontaneous early afterdepolarizations (EADs) and ventricular tachycardia/fibrillation occurred in 50% of hearts at 2.7 mmol/L [K] in the absence of dofetilide and 3.3 mmol/L [K] in its presence. Pretreatment with the Ca-calmodulin kinase II (CaMKII) inhibitor KN-93, but not its inactive analogue KN-92, abolished EADs and hypokalemia-induced ventricular tachycardia/fibrillation, as did the selective late Na current (INa) blocker GS-967. In intact hearts, moderate hypokalemia (2.7 mmol/L) significantly increased tissue CaMKII activity. Computer modeling revealed that EAD generation by hypokalemia (with or without dofetilide) required Na-K pump inhibition to induce intracellular Na and Ca overload with consequent CaMKII activation enhancing late INa and the L-type Ca current. K current suppression by hypokalemia and dofetilide alone in the absence of CaMKII activation were ineffective at causing EADs. CONCLUSIONS We conclude that Na-K pump inhibition by even moderate hypokalemia plays a critical role in promoting EAD-mediated arrhythmias by inducing a positive feedback cycle activating CaMKII and enhancing late INa. Class III antiarrhythmic drugs like dofetilide sensitize the heart to this positive feedback loop.
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Affiliation(s)
- Arash Pezhouman
- UCLA Cardiovascular Research Laboratory, Departments of Medicine (Cardiology) and Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA
| | - Neha Singh
- UCLA Cardiovascular Research Laboratory, Departments of Medicine (Cardiology) and Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA
| | - Zhen Song
- UCLA Cardiovascular Research Laboratory, Departments of Medicine (Cardiology) and Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA
| | - Michael Nivala
- UCLA Cardiovascular Research Laboratory, Departments of Medicine (Cardiology) and Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA
| | - Anahita Eskandari
- UCLA Cardiovascular Research Laboratory, Departments of Medicine (Cardiology) and Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA
| | - Hong Cao
- UCLA Cardiovascular Research Laboratory, Departments of Medicine (Cardiology) and Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA
| | - Aneesh Bapat
- UCLA Cardiovascular Research Laboratory, Departments of Medicine (Cardiology) and Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA
| | - Christopher Y Ko
- UCLA Cardiovascular Research Laboratory, Departments of Medicine (Cardiology) and Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA
| | - Thao Nguyen
- UCLA Cardiovascular Research Laboratory, Departments of Medicine (Cardiology) and Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA
| | - Zhilin Qu
- UCLA Cardiovascular Research Laboratory, Departments of Medicine (Cardiology) and Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA
| | - Hrayr S Karagueuzian
- UCLA Cardiovascular Research Laboratory, Departments of Medicine (Cardiology) and Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA
| | - James N Weiss
- UCLA Cardiovascular Research Laboratory, Departments of Medicine (Cardiology) and Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA
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Abstract
SIGNIFICANCE Oxygen plays a key role in cellular metabolism and function. Oxygen delivery to cells is crucial, and a lack of oxygen such as that which occurs during myocardial infarction can be lethal. Cells should, therefore, be able to respond to changes in oxygen tension. RECENT ADVANCES Since the first studies examining the acute cellular effect of hypoxia on activation of transmitter release from glomus or type I chemoreceptor cells, it is now known that virtually all cells are able to respond to changes in oxygen tension. CRITICAL ISSUES Despite advances made in characterizing hypoxic responses, the identity of the "oxygen sensor" remains debated. Recently, more evidence has evolved as to how cardiac myocytes sense acute changes in oxygen. This review will examine the available evidence in support of acute oxygen-sensing mechanisms providing a brief historical perspective and then more detailed insights into the heart and the role of cardiac ion channels in hypoxic responses. FUTURE DIRECTIONS A further understanding of these cellular processes should result in interventions that assist in preventing the deleterious effects of acute changes in oxygen tension such as alterations in contractile function and cardiac arrhythmia.
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Affiliation(s)
- Livia C Hool
- School of Anatomy, Physiology, and Human Biology, The University of Western Australia , Crawley, Australia
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11
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Driessen HE, Bourgonje VJA, van Veen TAB, Vos MA. New antiarrhythmic targets to control intracellular calcium handling. Neth Heart J 2014; 22:198-213. [PMID: 24733689 PMCID: PMC4016334 DOI: 10.1007/s12471-014-0549-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Sudden cardiac death due to ventricular arrhythmias is a major problem. Drug therapies to prevent SCD do not provide satisfying results, leading to the demand for new antiarrhythmic strategies. New targets include Ca2+/Calmodulin-dependent protein kinase II (CaMKII), the Na/Ca exchanger (NCX), the Ryanodine receptor (RyR, and its associated protein FKBP12.6 (Calstabin)) and the late component of the sodium current (INa-Late), all related to intracellular calcium (Ca2+) handling. In this review, drugs interfering with these targets (SEA-0400, K201, KN-93, W7, ranolazine, sophocarpine, and GS-967) are evaluated and their future as clinical compounds is considered. These new targets prove to be interesting; however more insight into long-term drug effects is necessary before clinical applicability becomes reality.
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Affiliation(s)
- H E Driessen
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Yalelaan 50, 3584 CM, Utrecht, the Netherlands,
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12
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The Lambeth Conventions (II): Guidelines for the study of animal and human ventricular and supraventricular arrhythmias. Pharmacol Ther 2013; 139:213-48. [DOI: 10.1016/j.pharmthera.2013.04.008] [Citation(s) in RCA: 208] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2013] [Accepted: 04/01/2013] [Indexed: 12/17/2022]
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13
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Fischer TH, Neef S, Maier LS. The Ca-calmodulin dependent kinase II: A promising target for future antiarrhythmic therapies? J Mol Cell Cardiol 2013; 58:182-7. [DOI: 10.1016/j.yjmcc.2012.11.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Revised: 11/02/2012] [Accepted: 11/05/2012] [Indexed: 12/19/2022]
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14
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Electrical storm: recent pathophysiological insights and therapeutic consequences. Basic Res Cardiol 2013; 108:336. [DOI: 10.1007/s00395-013-0336-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Revised: 01/29/2013] [Accepted: 02/04/2013] [Indexed: 01/01/2023]
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15
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Rokita AG, Anderson ME. New therapeutic targets in cardiology: arrhythmias and Ca2+/calmodulin-dependent kinase II (CaMKII). Circulation 2013; 126:2125-39. [PMID: 23091085 DOI: 10.1161/circulationaha.112.124990] [Citation(s) in RCA: 90] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Adam G Rokita
- Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA
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16
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Swaminathan PD, Purohit A, Hund TJ, Anderson ME. Calmodulin-dependent protein kinase II: linking heart failure and arrhythmias. Circ Res 2012; 110:1661-77. [PMID: 22679140 DOI: 10.1161/circresaha.111.243956] [Citation(s) in RCA: 215] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Understanding relationships between heart failure and arrhythmias, important causes of suffering and sudden death, remains an unmet goal for biomedical researchers and physicians. Evidence assembled over the past decade supports a view that activation of the multifunctional Ca(2+) and calmodulin-dependent protein kinase II (CaMKII) favors myocardial dysfunction and cell membrane electrical instability. CaMKII activation follows increases in intracellular Ca(2+) or oxidation, upstream signals with the capacity to transition CaMKII into a Ca(2+) and calmodulin-independent constitutively active enzyme. Constitutively active CaMKII appears poised to participate in disease pathways by catalyzing the phosphorylation of classes of protein targets important for excitation-contraction coupling and cell survival, including ion channels and Ca(2+) homeostatic proteins, and transcription factors that drive hypertrophic and inflammatory gene expression. This rich diversity of downstream targets helps to explain the potential for CaMKII to simultaneously affect mechanical and electrical properties of heart muscle cells. Proof-of-concept studies from a growing number of investigators show that CaMKII inhibition is beneficial for improving myocardial performance and for reducing arrhythmias. We review the molecular physiology of CaMKII and discuss CaMKII actions at key cellular targets and results of animal models of myocardial hypertrophy, dysfunction, and arrhythmias that suggest CaMKII inhibition may benefit myocardial function while reducing arrhythmias.
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Affiliation(s)
- Paari Dominic Swaminathan
- Division of Cardiovascular Medicine, Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
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17
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Bourgonje VJA, Schoenmakers M, Beekman JDM, van der Nagel R, Houtman MJC, Miedema LF, Antoons G, Sipido K, de Windt LJ, van Veen TAB, Vos MA. Relevance of calmodulin/CaMKII activation for arrhythmogenesis in the AV block dog. Heart Rhythm 2012; 9:1875-83. [PMID: 22846339 DOI: 10.1016/j.hrthm.2012.07.023] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2012] [Indexed: 11/25/2022]
Abstract
BACKGROUND The calcium-dependent signaling molecules calcineurin and calcium/calmodulin-dependent protein kinase II (CaMKII) both have been linked to decompensated hypertrophy and arrhythmias. CaMKII is also believed to be involved in acute modulation of ion channels. OBJECTIVE The purpose of this study was to determine the role of calcineurin and CaMKII in a dog model of compensated hypertrophy and a long QT phenotype. METHODS AV block was created in dogs to induce ventricular remodeling, including enhanced susceptibility to dofetilide-induced torsades de pointes arrhythmias. Dogs were treated with cyclosporin A for 3 weeks, which reduced calcineurin activity, as determined by mRNA expression levels of regulator of calcineurin 1 exon 4, but which was unable to prevent structural, contractile, or electrical remodeling and arrhythmias. Biopsies were taken before and at 2 or 9 weeks after AV block. Western blots were performed against phosphorylated and total CaMKII, phospholamban, Akt, and histone deacetylase 4 (HDAC4). RESULTS Chronic AV block showed an increase in Akt, CaMKII and phospholamban phosphorylation levels, but HDAC4 phosphorylation remained unaltered. Dofetilide induced torsades de pointes in vivo and early afterdepolarizations in cardiomyocytes, and increased [Ca(2+)](i) and CaMKII autophosphorylation. Both W-7 and KN-93 treatment counteracted this. CONCLUSION The calcineurin pathway seems not to be involved in long-term cardiac remodeling of the chronic AV block dog. Although CaMKII is chronically activated, this does not translate to HDAC4 phosphorylation. However, acute CaMKII overactivation is able to initiate arrhythmias based on triggered activity.
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Affiliation(s)
- Vincent J A Bourgonje
- Department of Medical Physiology, Division Heart & Lungs, University Medical Center Utrecht, Utrecht, The Netherlands.
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18
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Guo T, Zhang T, Ginsburg KS, Mishra S, Brown JH, Bers DM. CaMKIIδC slows [Ca]i decline in cardiac myocytes by promoting Ca sparks. Biophys J 2012; 102:2461-70. [PMID: 22713561 DOI: 10.1016/j.bpj.2012.04.015] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2012] [Revised: 03/12/2012] [Accepted: 04/02/2012] [Indexed: 11/19/2022] Open
Abstract
Acute activation of calcium/calmodulin-dependent protein kinase (CaMKII) in permeabilized phospholamban knockout (PLN-KO) mouse myocytes phosphorylates ryanodine receptors (RyRs) and activates spontaneous local sarcoplasmic reticulum (SR) Ca release events (Ca sparks) even at constant SR Ca load. To assess how CaMKII regulates SR Ca release in intact myocytes (independent of SR Ca content changes or PLN effects), we compared Ca sparks in PLN-KO versus mice, which also have transgenic cardiac overexpression of CaMKIIδC in the PLN-KO background (KO/TG). Compared with PLN-KO mice, these KO/TG cardiomyocytes exhibited 1), increased twitch Ca transient and fractional release (both by ∼35%), but unaltered SR Ca load; 2), increased resting Ca spark frequency (300%) despite a lower diastolic [Ca]i, which also slowed twitch [Ca]i decline (suggesting CaMKII-dependent RyR Ca sensitization); 3), elevated Ca spark amplitude and rate of Ca release (which might indicate that more RyR channels participate in a single spark); 4), prolonged Ca spark rise time (which implies that CaMKII either delays RyR closure or prolongs the time when openings can occur); 5), more frequent repetitive sparks at single release sites. Analysis of repetitive sparks from individual Ca release sites indicates that CaMKII enhanced RyR Ca sensitivity, but did not change the time course of SR Ca refilling. These results demonstrate that there are dramatic CaMKII-mediated effects on RyR Ca release that occur via regulation of both RyR activation and termination processes.
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Affiliation(s)
- Tao Guo
- Department of Pharmacology, University of California, Davis, Davis, California, USA
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19
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Fernández-Velasco M, Ruiz-Hurtado G, Rueda A, Neco P, Mercado-Morales M, Delgado C, Napolitano C, Priori SG, Richard S, María Gómez A, Benitah JP. RyRCa2+ leak limits cardiac Ca2+ window current overcoming the tonic effect of calmodulinin mice. PLoS One 2011; 6:e20863. [PMID: 21673970 PMCID: PMC3108979 DOI: 10.1371/journal.pone.0020863] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2010] [Accepted: 05/13/2011] [Indexed: 11/19/2022] Open
Abstract
Ca2+ mediates the functional coupling between L-type Ca2+ channel (LTCC) and sarcoplasmic reticulum (SR) Ca2+ release channel (ryanodine receptor, RyR), participating in key pathophysiological processes. This crosstalk manifests as the orthograde Ca2+-induced Ca2+-release (CICR) mechanism triggered by Ca2+ influx, but also as the retrograde Ca2+-dependent inactivation (CDI) of LTCC, which depends on both Ca2+ permeating through the LTCC itself and on SR Ca2+ release through the RyR. This latter effect has been suggested to rely on local rather than global Ca2+ signaling, which might parallel the nanodomain control of CDI carried out through calmodulin (CaM). Analyzing the CICR in catecholaminergic polymorphic ventricular tachycardia (CPVT) mice as a model of RyR-generated Ca2+ leak, we evidence here that increased occurrence of the discrete local SR Ca2+ releases through the RyRs (Ca2+ sparks) causea depolarizing shift in activation and a hyperpolarizing shift inisochronic inactivation of cardiac LTCC current resulting in the reduction of window current. Both increasing fast [Ca2+]i buffer capacity or depleting SR Ca2+ store blunted these changes, which could be reproduced in WT cells by RyRCa2+ leak induced with Ryanodol and CaM inhibition.Our results unveiled a new paradigm for CaM-dependent effect on LTCC gating and further the nanodomain Ca2+ control of LTCC, emphasizing the importance of spatio-temporal relationships between Ca2+ signals and CaM function.
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Affiliation(s)
- María Fernández-Velasco
- Inserm, U637, Université Montpellier-1, Université Montpellier-2, Montpellier, France
- Instituto de Investigaciones Biomédicas Alberto Sols CSIC-UAM, Madrid, Spain
| | - Gema Ruiz-Hurtado
- Inserm, U637, Université Montpellier-1, Université Montpellier-2, Montpellier, France
- Inserm, U769, IFR141, Faculté de Pharmacie, Université Paris-Sud 11, Chatenay-Malabry, France
| | - Angélica Rueda
- Inserm, U637, Université Montpellier-1, Université Montpellier-2, Montpellier, France
- Department of Biochemistry, CINVESTAV, Mexico City, Mexico
| | - Patricia Neco
- Inserm, U637, Université Montpellier-1, Université Montpellier-2, Montpellier, France
- Inserm, U769, IFR141, Faculté de Pharmacie, Université Paris-Sud 11, Chatenay-Malabry, France
| | | | - Carmen Delgado
- Departamento de Farmacología, Facultad de Medicina, Universidad Complutense, CyB, CSIC, Madrid, Spain
| | - Carlo Napolitano
- Molecular Cardiology, Fondazione Salvatore Maugeri, Pavia, Italy
- Cardiovascular Genetics, Leon Charney Division of Cardiology, Langone Medical Center, New York University School of Medicine, New York, United States of America
| | - Silvia G. Priori
- Molecular Cardiology, Fondazione Salvatore Maugeri, Pavia, Italy
- Cardiovascular Genetics, Leon Charney Division of Cardiology, Langone Medical Center, New York University School of Medicine, New York, United States of America
- Department of Cardiology, University of Pavia, Italy
| | - Sylvain Richard
- Inserm, U637, Université Montpellier-1, Université Montpellier-2, Montpellier, France
- Inserm, U1046, Université Montpellier-1, Université Montpellier-2, Montpellier, France
| | - Ana María Gómez
- Inserm, U637, Université Montpellier-1, Université Montpellier-2, Montpellier, France
- Inserm, U769, IFR141, Faculté de Pharmacie, Université Paris-Sud 11, Chatenay-Malabry, France
| | - Jean-Pierre Benitah
- Inserm, U637, Université Montpellier-1, Université Montpellier-2, Montpellier, France
- Inserm, U769, IFR141, Faculté de Pharmacie, Université Paris-Sud 11, Chatenay-Malabry, France
- * E-mail:
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20
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Su Z, Widomski DL, Liu X, Limberis JT, Green J, Diaz G, Martin RL, Cox BF, Gintant GA. A novel secretagogue increases cardiac contractility by enhancement of L-type Ca2+ current. Biochem Pharmacol 2010; 80:1000-6. [PMID: 20599796 DOI: 10.1016/j.bcp.2010.06.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2010] [Revised: 05/21/2010] [Accepted: 06/07/2010] [Indexed: 12/01/2022]
Abstract
N'1-(3,3,6,8-tetramethyl-1-oxo-1,2,3,4-tetrahydronaphthalen-2-yliden)-2-cyanoethanohydrazide (TTYC) increases secretion of glucagon-like peptide-1 and intracellular Ca(2+) concentration in GLUTag cells. The purpose of the present study was to examine if TTYC exerts positive inotropic effects on isolated rabbit ventricular myocytes and in vivo heart in anesthetized rats, and if so to further define the potential mechanism of action. Contractility was assessed in vitro using changes in fractional shortening (FS) of myocyte sarcomere length and in vivo using changes in the velocity of left ventricular pressure. Changes in L-type Ca(2+) current of ventricular myocytes were evaluated using whole-cell voltage-clamp techniques. TTYC increased FS of myocyte sarcomere length in a concentration-dependent manner. The positive inotropic effect was not abrogated by beta-adrenergic blockade (propranolol) or protein kinase A inhibition. TTYC enhanced peak L-type Ca(2+) current in a voltage-dependent manner (current amplitudes increased by 4.0-fold at -10 mV and 1.5-fold at +10 mV). Voltage-dependence of steady-state activation of L-type Ca(2+) current was shifted by 15 mV in the negative direction. Inactivation time course of the L-type Ca(2+) currents at voltages of -10 to 20 mV was significantly slowed by 0.3 microM TTYC. In vivo studies demonstrated that TTYC increased cardiac contractility in a dose-dependent manner. In conclusion, TTYC is a novel L-type Ca(2+) current activator with positive cardiac inotropic effects. Negative shifting of the voltage-dependence of L-type Ca(2+) current activation and reduced inactivation are two mechanisms responsible for the enhanced L-type Ca(2+) current that contribute to the positive inotropic effects.
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Affiliation(s)
- Zhi Su
- Department of Integrative Pharmacology, Global Pharmaceutical Research and Development, Abbott Laboratories, 100 Abbott Park Road, Abbott Park, IL 60064, USA.
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Farkas AS, Nattel S. Minimizing Repolarization-Related Proarrhythmic Risk in Drug Development and Clinical Practice. Drugs 2010; 70:573-603. [DOI: 10.2165/11535230-000000000-00000] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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22
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CaV1.2 beta-subunit coordinates CaMKII-triggered cardiomyocyte death and afterdepolarizations. Proc Natl Acad Sci U S A 2010; 107:4996-5000. [PMID: 20194790 DOI: 10.1073/pnas.0913760107] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Excessive activation of calmodulin kinase II (CaMKII) causes arrhythmias and heart failure, but the cellular mechanisms for CaMKII-targeted proteins causing disordered cell membrane excitability and myocardial dysfunction remain uncertain. Failing human cardiomyocytes exhibit increased CaMKII and voltage-gated Ca(2+) channel (Ca(V)1.2) activity, and enhanced expression of a specific Ca(V)1.2 beta-subunit protein isoform (beta(2a)). We recently identified Ca(V)1.2 beta(2a) residues critical for CaMKII phosphorylation (Thr 498) and binding (Leu 493), suggesting the hypothesis that these amino acids are crucial for cardiomyopathic consequences of CaMKII signaling. Here we show WT beta(2a) expression causes cellular Ca(2+) overload, arrhythmia-triggering cell membrane potential oscillations called early afterdepolarizations (EADs), and premature death in paced adult rabbit ventricular myocytes. Prevention of intracellular Ca(2+) release by ryanodine or global cellular CaMKII inhibition reduced EADs and improved cell survival to control levels in WT beta(2a)-expressing ventricular myocytes. In contrast, expression of beta(2a) T498A or L493A mutants mimicked the protective effects of ryanodine or global cellular CaMKII inhibition by reducing Ca(2+) entry through Ca(V)1.2 and inhibiting EADs. Furthermore, Ca(V)1.2 currents recorded from cells overexpressing CaMKII phosphorylation- or binding-incompetent beta(2a) subunits were incapable of entering a CaMKII-dependent high-activity gating mode (mode 2), indicating that beta(2a) Thr 498 and Leu 493 are required for Ca(V)1.2 activation by CaMKII in native cells. These data show that CaMKII binding and phosphorylation sites on beta(2a) are concise but pivotal components of a molecular and biophysical and mechanism for EADs and impaired survival in adult cardiomyocytes.
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23
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Kijtawornrat A, Ziolo MT, Nishijima Y, Roche BM, Hamlin RL. Effects of Sarcolemmal Ca2+ Entry, Ryanodine Function, and Kinase Inhibitors on a Rabbit Model of Heart Failure. Int Heart J 2010; 51:285-90. [DOI: 10.1536/ihj.51.285] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
| | - Mark T. Ziolo
- Department of Physiology and Cell Biology, The Ohio State University
| | - Yoshinori Nishijima
- Department of Veterinary Biosciences, The Ohio State University
- QTest Labs, LLC., 6456 Fiesta Drive
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Takahara A, Nakamura Y, Wagatsuma H, Aritomi S, Nakayama A, Satoh Y, Akie Y, Sugiyama A. Long-term blockade of L/N-type Ca(2+) channels by cilnidipine ameliorates repolarization abnormality of the canine hypertrophied heart. Br J Pharmacol 2009; 158:1366-74. [PMID: 19785655 PMCID: PMC2782346 DOI: 10.1111/j.1476-5381.2009.00407.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2009] [Revised: 05/27/2009] [Accepted: 06/09/2009] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND AND PURPOSE The heart of the canine model of chronic atrioventricular block is known to have a ventricular electrical remodelling, which mimics the pathophysiology of long QT syndrome. Using this model, we explored a new pharmacological therapeutic strategy for the prevention of cardiac sudden death. EXPERIMENTAL APPROACH The L-type Ca(2+) channel blocker amlodipine (2.5 mg.day(-1)), L/N-type Ca(2+) channel blocker cilnidipine (5 mg.day(-1)), or the angiotensin II receptor blocker candesartan (12 mg.day(-1)) was administered orally to the dogs with chronic atrioventricular block for 4 weeks. Electropharmacological assessments with the monophasic action potential (MAP) recordings and blood sample analyses were performed before and 4 weeks after the start of drug administration. KEY RESULTS Amlodipine and cilnidipine decreased the blood pressure, while candesartan hardly affected it. The QT interval, MAP duration and beat-to-beat variability of the ventricular repolarization period were shortened only in the cilnidipine group, but such effects were not observed in the amlodipine or candesartan group. Plasma concentrations of adrenaline, angiotensin II and aldosterone decreased in the cilnidipine group. In contrast, plasma concentrations of angiotensin II and aldosterone were elevated in the amlodipine group, whereas in the candesartan group an increase in plasma levels of angiotensin II and a decrease in noradrenaline and adrenaline concentrations were observed. CONCLUSIONS AND IMPLICATIONS Long-term blockade of L/N-type Ca(2+) channels ameliorated the ventricular electrical remodelling in the hypertrophied heart which causes the prolongation of the QT interval. This could provide a novel therapeutic strategy for the treatment of cardiovascular diseases.
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Affiliation(s)
- A Takahara
- Department of Pharmacology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Yamanashi, Japan
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Gaur N, Rudy Y, Hool L. Contributions of ion channel currents to ventricular action potential changes and induction of early afterdepolarizations during acute hypoxia. Circ Res 2009; 105:1196-203. [PMID: 19875728 DOI: 10.1161/circresaha.109.202267] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
RATIONALE Variability in delivery of oxygen can lead to electric instability in the myocardium and the generation of arrhythmias. In addition ischemic heart disease and angina are associated with an increase in circulating catecholamines that further increases the risk of developing ventricular tachyarrhythmias. OBJECTIVE We investigated the net effects of acute hypoxia and catecholamines on the cardiac action potential. METHODS AND RESULTS We incorporated all published data on the effects of hypoxia on the late Na(+) current (I(Na-L)), the fast Na(+) current (I(Na)), the basal L-type Ca(2+) channel current (I(Ca-L)), and the slow (I(Ks)) and rapid components of the delayed rectifier K(+)-current (I(Kr)) in the absence and presence of beta-adrenergic receptor (beta-AR) stimulation into the Luo-Rudy model of the action potential. Hypoxia alone had little effect on the action potential configuration or action potential duration. However in the presence of beta-AR stimulation, hypoxia caused a prolongation of the action potential and early afterdepolarizations (EADs) and spontaneous tachycardia were induced. Experiments performed in guinea pig ventricular myocytes confirmed the modeling results. CONCLUSIONS EADs occur predominantly because of the increased sensitivity of I(Ca-L) to beta-AR stimulation during hypoxia. beta-AR stimulation is necessary to induce EADs as EADs are never observed during hypoxia in the absence of beta-AR stimulation.
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Affiliation(s)
- Namit Gaur
- Physiology M311, School of Biomedical, Biomolecular and Chemical Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
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Sag CM, Wadsack DP, Khabbazzadeh S, Abesser M, Grefe C, Neumann K, Opiela MK, Backs J, Olson EN, Brown JH, Neef S, Maier SKG, Maier LS. Calcium/calmodulin-dependent protein kinase II contributes to cardiac arrhythmogenesis in heart failure. Circ Heart Fail 2009; 2:664-75. [PMID: 19919992 DOI: 10.1161/circheartfailure.109.865279] [Citation(s) in RCA: 137] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND Transgenic (TG) Ca/calmodulin-dependent protein kinase II (CaMKII)delta(C) mice have heart failure and isoproterenol (ISO)-inducible arrhythmias. We hypothesized that CaMKII contributes to arrhythmias and underlying cellular events and that inhibition of CaMKII reduces cardiac arrhythmogenesis in vitro and in vivo. METHODS AND RESULTS Under baseline conditions, isolated cardiac myocytes from TG mice showed an increased incidence of early afterdepolarizations compared with wild-type myocytes (P<0.05). CaMKII inhibition (AIP) completely abolished these afterdepolarizations in TG cells (P<0.05). Increasing intracellular Ca stores using ISO (10(-8) M) induced a larger amount of delayed afterdepolarizations and spontaneous action potentials in TG compared with wild-type cells (P<0.05). This seems to be due to an increased sarcoplasmic reticulum (SR) Ca leak because diastolic [Ca](i) rose clearly on ISO in TG but not in wild-type cells (+20+/-5% versus +3+/-4% at 10(-6) M ISO, P<0.05). In parallel, SR Ca leak assessed by spontaneous SR Ca release events showed an increased Ca spark frequency (3.9+/-0.5 versus 2.0+/-0.4 sparks per 100 microm(-1).s(-1), P<0.05). However, CaMKII inhibition (either pharmacologically using KN-93 or genetically using an isoform-specific CaMKIIdelta-knockout mouse model) significantly reduced SR Ca spark frequency, although this rather increased SR Ca content. In parallel, ISO increased the incidence of early (54% versus 4%, P<0.05) and late (86% versus 43%, P<0.05) nonstimulated events in TG versus wild-type myocytes, but CaMKII inhibition (KN-93 and KO) reduced these proarrhythmogenic events (P<0.05). In addition, CaMKII inhibition in TG mice (KN-93) clearly reduced ISO-induced arrhythmias in vivo (P<0.05). CONCLUSIONS We conclude that CaMKII contributes to cardiac arrhythmogenesis in TG CaMKIIdelta(C) mice having heart failure and suggest the increased SR Ca leak as an important mechanism. Moreover, CaMKII inhibition reduces cardiac arrhythmias in vitro and in vivo and may therefore indicate a potential role for future antiarrhythmic therapies warranting further studies.
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Affiliation(s)
- Can M Sag
- Department of Cardiology and Pneumology, Heart Center, Georg-August-University, Göttingen, Germany
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Abstract
Human heart disease is a major cause of death and disability. A variety of animal models of cardiac disease have been developed to better understand the etiology, cellular and molecular mechanisms of cardiac dysfunction and novel therapeutic strategies. The animal models have included large animals (e.g. pig and dog) and small rodents (e.g. mouse and rat) and the advantages of genetic manipulation in mice have appropriately encouraged the development of novel mouse models of cardiac disease. However, there are major differences between rodent and human hearts that raise cautions about the extrapolation of results from mouse to human. The rabbit is a medium-sized animal that has many cellular and molecular characteristics very much like human, and is a practical alternative to larger mammals. Numerous rabbit models of cardiac disease are discussed, including pressure or volume overload, ischemia, rapid-pacing, doxorubicin, drug-induced arrhythmias, transgenesis and infection. These models also lead to the assessment of therapeutic strategies which may become beneficial in human cardiac disease. Ju Chen – University of California, San Diego, Department of Medicine, La Jolla, CA, USA Robert Ross – University of California, San Diego, Cardiology Section, San Diego, CA, USA
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Affiliation(s)
- Steven M Pogwizd
- Departments of Medicine, Physiology, and Biophysics & Bioengineering, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Donald M Bers
- Department of Pharmacology, University of California Davis, Genome Building 3513, Davis, CA 95616-8636, United States
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Hool LC. The L-type Ca(2+) channel as a potential mediator of pathology during alterations in cellular redox state. Heart Lung Circ 2008; 18:3-10. [PMID: 19119068 DOI: 10.1016/j.hlc.2008.11.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The L-type Ca(2+) channel is the main route for calcium influx into cardiac myocytes and an important determinant of calcium homeostasis. There is now considerable evidence that the function of the L-type Ca(2+) channel is influenced by the cell's redox state. Reactive oxygen species such as hydrogen peroxide and superoxide can regulate biological function by directly altering the thiol redox state of proteins. Under conditions where cellular redox state varies, L-type Ca(2+) channel function and diastolic calcium levels can be significantly altered. This article will present the evidence for alterations in L-type Ca(2+) channel function by reactive oxygen species and the potential role for the channel in development of acute electrophysiological instability or chronic pathological remodelling under conditions of persistent oxidative stress.
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Affiliation(s)
- Livia C Hool
- School of Biomedical, Biomolecular and Chemical Sciences and The Western Australian Institute for Medical Research, The University of Western Australia, Crawley, Western Australia, Australia.
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29
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Yarotskyy V, Gao G, Peterson BZ, Elmslie KS. The Timothy syndrome mutation of cardiac CaV1.2 (L-type) channels: multiple altered gating mechanisms and pharmacological restoration of inactivation. J Physiol 2008; 587:551-65. [PMID: 19074970 DOI: 10.1113/jphysiol.2008.161737] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Timothy syndrome (TS) is a multiorgan dysfunction caused by a Gly to Arg substitution at position 406 (G406R) of the human CaV1.2 (L-type) channel. The TS phenotype includes severe arrhythmias that are thought to be triggered by impaired open-state voltage-dependent inactivation (OSvdI). The effect of the TS mutation on other L-channel gating mechanisms has yet to be investigated. We compared kinetic properties of exogenously expressed (HEK293 cells) rabbit cardiac L-channels with (G436R; corresponding to position 406 in human clone) and without (wild-type) the TS mutation. Our results surprisingly show that the TS mutation did not affect close-state voltage-dependent inactivation, which suggests different gating mechanisms underlie these two types of voltage-dependent inactivation. The TS mutation also significantly slowed activation at voltages less than 10 mV, and significantly slowed deactivation across all test voltages. Deactivation was slowed in the double mutant G436R/S439A, which suggests that phosphorylation of S439 was not involved. The L-channel agonist Bay K8644 increased the magnitude of both step and tail currents, but surprisingly failed to slow deactivation of TS channels. Our mathematical model showed that slowed deactivation plus impaired OSvdI combine to synergistically increase cardiac action potential duration that is a likely cause of arrhythmias in TS patients. Roscovitine, a tri-substituted purine that enhances L-channel OSvdI, restored TS-impaired OSvdI. Thus, inactivation-enhancing drugs are likely to improve cardiac arrhythmias and other pathologies afflicting TS patients.
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Affiliation(s)
- Viktor Yarotskyy
- Department of Anesthesiology, Penn State College of Medicine, 500 University Drive, Hershey, PA 17033, USA
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30
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Inaba H, Hayami N, Ajiki K, Sugishita Y, Kunishima T, Yamagishi N, Yamagishi S, Murakawa Y. Human atrial natriuretic peptide suppresses torsades de pointes in rabbits. Circ J 2008; 72:820-4. [PMID: 18441465 DOI: 10.1253/circj.72.820] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND The increase in inward current, primarily L-type Ca2+ current, facilitates torsades de pointes (TdP). Because human atrial natriuretic peptide (ANP) moderates the L-type Ca2+ current, in our study it was hypothesized that ANP counteracts TdP. METHODS AND RESULTS We tested the effect of ANP, guanosine 3', 5'-cyclic monophosphate analogue (8-bromo cGMP) and hydralazine on the occurrence of TdP in a rabbit model. In control rabbits, administration of methoxamine and nifekalant almost invariably caused TdP (14/15). In contrast, ANP (10 microg . kg(-1) . min(-1)) markedly abolished TdP (2/15), whereas hydralazine failed to show a comparable anti-arrhythmic action (10/15). TdP occurred only in 1 of 15 rabbits treated with 8-bromo cGMP. Presence of early afterdepolarization-like hump in the ventricular monophasic action potential was associated with the occurrence of TdP. CONCLUSION Results suggest that ANP affects TdP in the rabbit model, and that this anti-arrhythmic effect of ANP is not necessarily shared by other vasodilating agents.
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Affiliation(s)
- Hideko Inaba
- Fourth Department of Internal Medicine, Mizonokuchi Hospital, Teikyo University School of Medicine, Kawasaki, Japan
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31
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Abstract
Abnormalities in heart rhythm continue to cause high rates of illness and death. Better treatment could be provided by solving two main challenges: the early identification of patients who are at risk, and the characterization of molecular pathways that culminate in arrhythmias. By analysing mechanisms that increase susceptibility to arrhythmia in individuals with genetic syndromes, it might be possible to improve current therapies and to develop new ways to treat and prevent common arrhythmias.
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Antoons G, Oros A, Bito V, Sipido KR, Vos MA. Cellular basis for triggered ventricular arrhythmias that occur in the setting of compensated hypertrophy and heart failure: considerations for diagnosis and treatment. J Electrocardiol 2007; 40:S8-14. [DOI: 10.1016/j.jelectrocard.2007.05.022] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2007] [Accepted: 05/30/2007] [Indexed: 10/22/2022]
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Vincze D, Farkas AS, Rudas L, Makra P, Csík N, Leprán I, Forster T, Csanády M, Papp JG, Varró A, Farkas A. Relevance of anaesthesia for dofetilide-induced torsades de pointes in alpha1-adrenoceptor-stimulated rabbits. Br J Pharmacol 2007; 153:75-89. [PMID: 17965737 DOI: 10.1038/sj.bjp.0707536] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND AND PURPOSE No information is available concerning the effects of anaesthetics in the most frequently used in vivo pro-arrhythmia model. Accordingly, in this study we examined the effect of pentobarbital, propofol or alpha-chloralose anaesthesia on the pro-arrhythmic activity of the class III anti-arrhythmic dofetilide in alpha(1)-adrenoceptor-stimulated rabbits. EXPERIMENTAL APPROACH Rabbits anaesthetized intravenously with pentobarbital, propofol or alpha-chloralose were infused simultaneously with the alpha(1)-adrenoceptor agonist phenylephrine (15 microg kg(-1) min(-1), i.v.) and dofetilide (0.04 mg kg(-1) min(-1), i.v.). The electrocardiographic QT interval, the T (peak)-T (end) interval and certain QT variability parameters were measured. The heart rate variability and the baroreflex sensitivity were utilized to assess the vagal nerve activity. The spectral power of the systolic arterial pressure was calculated in the frequency range 0.15-0.5 Hz to assess the sympathetic activity. KEY RESULTS Pentobarbital considerably reduced, whereas propofol did not significantly affect the incidence of dofetilide-induced torsades de pointes (TdP) as compared with the results with alpha-chloralose (40% (P=0.011) and 70% (P=0.211) vs 100%, respectively). In additional experiments, neither doubling of the rate of the dofetilide infusion nor tripling of the rate of phenylephrine infusion elevated the incidence of TdP to the level seen with alpha-chloralose. None of the repolarization-related parameters predicted TdP. The indices of the parasympathetic and sympathetic activity were significantly depressed in the alpha-chloralose and propofol anaesthesia groups. CONCLUSIONS AND IMPLICATIONS In rabbits, anaesthetics may affect drug-induced TdP genesis differently, which must be considered when results of different studies are compared.
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Affiliation(s)
- D Vincze
- Department of Anaesthesiology and Intensive Care, University of Szeged, Szeged, Hungary
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Huang ZJ, Dai DZ, Li N, Na T, Ji M, Dai Y. Calcium antagonist property of CPU228, a dofetilide derivative, contributes to its low incidence of torsades de pointes in rabbits. Clin Exp Pharmacol Physiol 2007; 34:310-7. [PMID: 17324143 DOI: 10.1111/j.1440-1681.2007.04555.x] [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] [Indexed: 11/27/2022]
Abstract
1. Torsades de pointes (TDP) is a severe adverse effect during the clinical use of dofetilide, a selective blocker of the rapid component of the delayed rectifier potassium channel (I(Kr)). The present study was designed to test whether CPU228, a derivative of dofetilide with calcium (Ca(2+)) antagonist properties, could reduce TDP without reducing the blockade of I(Kr). 2. The incidence of TDP in a rabbit model and the effective refractory period (ERP) were measured and compared for dofetilide and CPU228. Suppression of I(Kr) and the L-type Ca(2+) current (I(Ca,L)) and the Ca(2+) transients of isolated cardiomyocytes were investigated by whole-cell patch-clamp and Fluo-3 dye spectrophotometry. 3. The incidence of TDP was greatly reduced by CPU228 relative to dofetilide, occurring in only one of six rabbits compared with five of six rabbits following dofetilide (P < 0.05). In isolated atria, prolongation of ERP by CPU228 was less than that of dofetilide and no reverse frequency dependence was observed. Negative inotropism by CPU228 was significant against positive inotropism by dofetilide. CPU228 inhibited both I(Kr) and I(Ca,L) currents and the IC(50) for I(Ca,L) inhibition was 0.909 micromol/L. At 3 micromol/L, CPU228 significantly suppressed the Ca(2+) transients. 4. CPU228 is able to block I(Ca,L), contributing to decreased TDP, while also blocking I(Kr) activity. By combined blockade of I(Kr) and I(Ca,L), CPU228 shares the property of complex Class III anti-arrhythmic agents.
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Affiliation(s)
- Zhi-Jiang Huang
- Research Division of Pharmacology, China Pharmaceutical University, Nanjing 210009, China
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Anderson ME. Multiple downstream proarrhythmic targets for calmodulin kinase II: Moving beyond an ion channel-centric focus. Cardiovasc Res 2007; 73:657-66. [PMID: 17254559 DOI: 10.1016/j.cardiores.2006.12.009] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2006] [Revised: 12/08/2006] [Accepted: 12/11/2006] [Indexed: 11/21/2022] Open
Abstract
The multifunctional Ca(2+) calmodulin-dependent protein kinase II (CaMKII) has emerged as a pro-arrhythmic signaling molecule. CaMKII can participate in arrhythmia signaling by effects on ion channel proteins, intracellular Ca(2+) uptake and release, regulation of cell death, and by activation of hypertrophic signaling pathways. The pleuripotent nature of CaMKII is reminiscent of another serine-threonine kinase, protein kinase A (PKA), which shares many of the same protein targets and is the downstream kinase most associated with beta-adrenergic receptor stimulation. The ability of CaMKII to localize and coordinate activity of multiple protein targets linked to Ca(2+) signaling set CaMKII apart from other "traditional" arrhythmia drug targets, such as ion channel proteins. This review will discuss some of the biology of CaMKII and focus on work that has been done on molecular, cellular, and whole animal models that together build a case for CaMKII as a pro-arrhythmic signal and as a potential therapeutic target for arrhythmias and structural heart disease.
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Affiliation(s)
- Mark E Anderson
- University of Iowa, Carver College of Medicine, Department of Internal Medicine, 200 Hawkins Drive, E315-A1 GH, Iowa City, IA 52242 USA.
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36
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Abstract
Limitations in understanding of arrhythmias stem from lack of animal models which serve as surrogates for man. The purpose of this review is to discuss iatrogenic and naturally occurring animal models that are useful in our understanding of the mechanisms of ventricular arrhythmia and of antiarrhythmic and proarrhythmic agents. It is not surprising however that some information obtained from studies on infrahuman mammals may not be extrapolated to man. Need for anesthesia affects profoundly the electrophysiology of the heart, including autonomic affects. Most of the animal are modification of the Harris' 2-stage model. A model proposed by Schwartz, Billman and Stone has evolved as one that produces arguably the most information on the pathophysiology of arrhythmia production, including the role of the autonomic nervous system and the interaction with pharmacological agents. Intoxication with digitalis and escalating doses of epinephrine are commonly used models for production of ventricular arrhythmias. No matter what model of ventricular arrhythmias is used, programmed electrical stimulation can be useful to uncover increased tendency for arrhythmia, even if no arrhythmia occurs spontaneously. Models of spontaneous ventricular arrhythmia occur in German shepherd puppies, Boxer dogs, Doberman pinchers with dilated cardiomyopathy, and in large dogs with gastric dilatation or splenic torsion. Models are necessary because they allow for controlled studies and methods of exploration impossible, for legal and ethical reasons, in humans. Nonetheless, ethical considerations in using animal models are still important, and there is a continual search for non-animal models to explore ventricular arrhythmias.
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Affiliation(s)
- Robert L Hamlin
- Department of Veterinary Biosciences, The Ohio State University, OH, USA.
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37
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Qu YJ, Bondarenko VE, Xie C, Wang S, Awayda MS, Strauss HC, Morales MJ. W-7 modulates Kv4.3: pore block and Ca2+-calmodulin inhibition. Am J Physiol Heart Circ Physiol 2007; 292:H2364-77. [PMID: 17220193 DOI: 10.1152/ajpheart.00409.2005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ca(+)-calmodulin (Ca(2+)-CaM)-dependent protein kinase II (Ca(2+)/CaMKII) is an important regulator of cardiac ion channels, and its inhibition may be an approach for treatment of ventricular arrhythmias. Using the two-electrode voltage-clamp technique, we investigated the role of W-7, an inhibitor of Ca(2+)-occupied CaM, and KN-93, an inhibitor of Ca(2+)/CaMKII, on the K(v)4.3 channel in Xenopus laevis oocytes. W-7 caused a voltage- and concentration-dependent decrease in peak current, with IC(50) of 92.4 muM. The block was voltage dependent, with an effective electrical distance of 0.18 +/- 0.05, and use dependence was observed, suggesting that a component of W-7 inhibition of K(v)4.3 current was due to open-channel block. W-7 made recovery from open-state inactivation a biexponential process, also suggesting open-channel block. We compared the effects of W-7 with those of KN-93 after washout of 500 muM BAPTA-AM. KN-93 reduced peak current without evidence of voltage or use dependence. Both W-7 and KN-93 accelerated all components of inactivation. We used wild-type and mutated K(v)4.3 channels with mutant CaMKII consensus phosphorylation sites to examine the effects of W-7 and KN-93. In contrast to W-7, KN-93 at 35 muM selectively accelerated open-state inactivation in the wild-type vs. the mutant channel. W-7 had a significantly greater effect on recovery from inactivation in wild-type than in mutant channels. We conclude that, at certain concentrations, KN-93 selectively inhibits Ca(2+)/CaMKII activity in Xenopus oocytes and that the effects of W-7 are mediated by direct interaction with the channel pore and inhibition of Ca(2+)-CaM, as well as a change in activity of Ca(2+)-CaM-dependent enzymes, including Ca(2+)/CaMKII.
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Affiliation(s)
- Yu-Jie Qu
- Department of Physiology and Biophysics, School of Medicine and Biomedical Sciences, University at Buffalo-State University of New York, 3435 Main Street, Buffalo, NY 14214, USA
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Hasumi H, Matsuda R, Shimamoto K, Hata Y, Kaneko N. K201, a multi-channel blocker, inhibits clofilium-induced torsades de pointes and attenuates an increase in repolarization. Eur J Pharmacol 2006; 555:54-60. [PMID: 17112502 DOI: 10.1016/j.ejphar.2006.10.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2006] [Revised: 10/03/2006] [Accepted: 10/05/2006] [Indexed: 11/16/2022]
Abstract
K201 (JTV519) is a 1,4-benzothiazepine derivative that exhibits a strong cardioprotective action and acts as a multiple-channel blocker, including as a K+ channel blocker. An experimental model of prolongation of the QT interval and torsades de pointes can be induced in rabbits by treatment with clofilium in the presence of the alpha1-adrenoreceptor agonist methoxamine. In this study we examined the effects of K201 with and without methoxamine on the QT and QTc intervals, and determined whether K201 inhibits clofilium-induced torsades de pointes in the presence of methoxamine (15 microg/kg/min) in rabbits (n=74). Administration of K201 (0, 40, 100, 200 and 400 microg/kg/min) with and without methoxamine prolonged the QT interval in a dose-dependent manner, and torsades de pointes did not occur in any animals. However, clofilium (50 microg/kg/min) with methoxamine induced torsades de pointes in all animals (6/6). Torsades de pointes occurred at rates of 100%, 67%, 40% and 0% at K201 concentrations of 0, 50, 200 and 400 microg/kg/min, respectively, in the clofilium-infused torsades de pointes model. Therefore, 400 microg/kg/min of K201 completely inhibited clofilium-induced torsades de pointes and attenuated the increase of repolarization caused by clofilium; the inhibitory effects of K201 may be related to its pharmacological properties as an alpha1-adrenoceptor blocker. Overall, our results show that K201 causes prolongation of the QT and QTc intervals, but does not induce torsades de pointes, with and without alpha1-adrenoceptor stimulation. Furthermore, K201 inhibits clofilium-induced torsades de pointes, despite QT prolongation, suggesting that QT prolongation alone is not a proarrhythmic signal.
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Affiliation(s)
- Hisashi Hasumi
- Department of Cardiology and Pneumology, Dokkyo Medical University School of Medicine 880 Kitakobayashi, Mibu, Tochigi, Japan
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Lu HR, Vlaminckx E, Van de Water A, Gallacher DJ. Calmodulin antagonist W-7 prevents sparfloxacin-induced early afterdepolarizations (EADs) in isolated rabbit purkinje fibers: importance of beat-to-beat instability of the repolarization. J Cardiovasc Electrophysiol 2006; 17:415-22. [PMID: 16643366 DOI: 10.1111/j.1540-8167.2006.00420.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
INTRODUCTION The occurrence of early afterdepolarizations (EADs) has been related to the incidence of torsades de pointes in drug-induced long QT (LQT). The generation of EADs may be facilitated by Ca(2+)/calmodulin-dependent protein kinase II (CaM kinase). METHODS AND RESULTS In the present study, we investigated a possible involvement of Ca(2+)/Calmodulin dependent protein kinase in the generation of sparfloxacin-induced EADs in isolated rabbit Purkinje fibers by means of a calmodulin antagonist W-7. EADs were evident in 8 of the 10 preparations perfused with sparfloxacin at 1 x 10(-4) M and stimulated at 0.2 Hz. The induction of EADs by sparfloxacin was associated with a large prolongation of the duration of the action potential (APD), an increase in the triangulation, and the short-term instability of the repolarization. CaM kinase blockade with the calmodulin antagonist W-7 inhibited sparfloxacin-induced EADs in a concentration-dependent manner (EADs were induced in 3 of 10, 1 of 10, and 0 of 8 preparations in the presence of W-7 at 5 x 10(-7) M, 5 x 10(-6) M, and 5 x 10(-5) M, respectively; P < 0.01 at 5 x 10(-6) M and 5 x 10(-5) M). The inhibition of sparfloxacin-induced EADs by W-7 at 5 x 10(-7) M and 5 x 10(-6) M was associated with a significant decrease in the beat-to-beat instability but not associated with a significant shortening of the APD and reduction of V(max). CONCLUSION The present findings support the hypothesis that CaM kinase may be a proarrhythmic signaling molecule and demonstrate that CaM kinase may be involved in the generation of EADs in drug-induced LQT and enhanced beat-to-beat instability of repolarization is essential for the genesis of EADs in rabbit in vitro.
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Affiliation(s)
- Hua Rong Lu
- Cardiovascular Safety Research, Johnson & Johnson Pharmaceutical Research & Development, a Division of Janssen Pharmaceutica N.V. B-2340, Beerse, Belgium.
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Thomsen MB, Volders PGA, Beekman JDM, Matz J, Vos MA. Beat-to-Beat variability of repolarization determines proarrhythmic outcome in dogs susceptible to drug-induced torsades de pointes. J Am Coll Cardiol 2006; 48:1268-76. [PMID: 16979017 DOI: 10.1016/j.jacc.2006.05.048] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2006] [Revised: 05/04/2006] [Accepted: 05/09/2006] [Indexed: 01/08/2023]
Abstract
OBJECTIVES We investigated whether increasing or decreasing beat-to-beat variability of repolarization (BVR) would change drug-induced proarrhythmic outcome accordingly. BACKGROUND Increased variability of repolarization has been suggested as a prelude to proarrhythmic circumstances in experimental and clinical situations. METHODS The non-cardiovascular, I(Kr)-blocking drug sertindole was administered to anesthetized dogs with chronic atrioventricular block. Three interventions were used to prevent or suppress sertindole-induced torsades de pointes (TdP). RESULTS Supratherapeutic doses of sertindole (1.0 mg/kg intravenously) induced TdP in 10 of 13 dogs whereas 0.2 mg/kg induced no TdP, despite increases in QT intervals by both doses. The BVR, quantified as short-term variability (STV) from Poincaré plots, was the only parameter that predicted TdP outcome (1.0 mg/kg sertindole: 2.3 +/- 0.7 ms to 5.1 +/- 2.1 ms, p < 0.05; 0.2 mg/kg sertindole: 2.3 +/- 0.8 ms to 3.2 +/- 1.1 ms, p= NS). INTERVENTIONS 1) KCl, intravenous, reduced the incidence of sertindole-induced TdP from 6 of 7 to 1 of 7 dogs (p<0.05) and prevented sertindole-related increase of STV: 3.0 +/- 1.1 ms vs. 4.5 +/- 1.3 ms (p < 0.05); 2) levcromakalim (I(K,ATP) activator) reduced sertindole-induced TdP and decreased STV from 4.9 +/- 2.1 ms to 2.6 +/- 0.9 ms (p < 0.05); 3) steady-state ventricular pacing (60 beats/min) abolished sertindole-induced TdP and decreased STV from 4.9 +/- 1.5 to 3.2 +/- 1.0 (p < 0.05). Torsades de pointes reappeared upon return to non-paced idioventricular rhythm. None of the 3 interventions reduced the sertindole-induced prolonged QT interval. CONCLUSIONS Proarrhythmic intervention is related to an increase in BVR, whereas antiarrhythmic treatment is associated with a decrease in BVR. The BVR is superior to QT interval prolongation in the prediction and prevention of drug-induced TdP in this experimental model.
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Affiliation(s)
- Morten B Thomsen
- Department of Medical Physiology, Heart Lung Center Utrecht, University Medical Center Utrecht, Utrecht, The Netherlands
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Kijtawornrat A, Nishijima Y, Roche BM, Keene BW, Hamlin RL. Use of a Failing Rabbit Heart as a Model to Predict Torsadogenicity. Toxicol Sci 2006; 93:205-12. [PMID: 16740615 DOI: 10.1093/toxsci/kfl025] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Humans with underlying cardiovascular disease are at greater risk than humans with normal hearts for developing torsade de pointes (TdP) following exposure to some drugs that prolong ventricular repolarization. This study was designed to test the hypothesis that rabbits with ischemic myocardial failure are at similarly increased risk of developing QTc prolongation and TdP following exposure to escalating doses of drugs, which is known to have a capacity to induce TdP in humans. Coronary artery ligation was performed in 28 rabbits, causing significant (p < 0.05) reduction in left ventricular shortening fraction and systolic myocardial dysfunction 4 weeks after ligation in all operated animals compared to 38 normal, nonoperated controls. All studies were performed on rabbits anesthetized with ketamine (35 mg/kg) and xylazine (5 mg/kg). Rabbits were exposed to escalating doses of amiodarone (3, 10, 30 mg/kg/10 min), cisapride (0.10, 0.25, 0.50 mg/kg/10 min), clofilium (0.1, 0.2, 0.4 mg/kg/10 min), dofetilide (0.005, 0.01, 0.02, 0.04 mg/kg/10 min), quinidine (3, 10, 30 mg/kg/10 min), and verapamil (0.25, 0.5, 1.0 mg/kg/10 min). A greater percentage of rabbits with failing hearts developed TdP following intravenous infusion of escalating doses of dofetilide (85%), clofilium (100%), or cisapride (50%) than did normal rabbits exposed to the same drug protocol (20, 33, and 0%, respectively). None of the rabbits in either group developed TdP when exposed to escalating doses of amiodarone, verapamil, or quinidine. Two out of four test articles lengthened QTc more in rabbits with myocardial failure than in normals, and TdP occurred in 13 out of 28 rabbits with myocardial failure as opposed to only four out of 38 rabbits with normal myocardial function.
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Affiliation(s)
- Anusak Kijtawornrat
- Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio 43210, USA
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Thomsen MB, Matz J, Volders PGA, Vos MA. Assessing the proarrhythmic potential of drugs: current status of models and surrogate parameters of torsades de pointes arrhythmias. Pharmacol Ther 2006; 112:150-70. [PMID: 16714061 DOI: 10.1016/j.pharmthera.2005.04.009] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2005] [Accepted: 04/06/2005] [Indexed: 02/08/2023]
Abstract
Torsades de pointes (TdP) is a potentially lethal cardiac arrhythmia that can occur as an unwanted adverse effect of various pharmacological therapies. Before a drug is approved for marketing, its effects on cardiac repolarisation are examined clinically and experimentally. This paper expresses the opinion that effects on repolarisation duration cannot directly be translated to risk of proarrhythmia. Current safety assessments of drugs only involve repolarisation assays, however the proarrhythmic profile can only be determined in the predisposed model. The availability of these proarrhythmic animal models is emphasised in the present paper. It is feasible for the pharmaceutical industry to establish one or more of these proarrhythmic animal models and large benefits are potentially available if pharmaceutical industries and patient-care authorities embraced these models. Furthermore, suggested surrogate parameters possessing predictive power of TdP arrhythmia are reviewed. As these parameters are not developed to finalisation, any meaningful study of the proarrhythmic potential of a new drug will include evaluation in an integrated model of TdP arrhythmia.
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Affiliation(s)
- Morten B Thomsen
- Department of Medical Physiology, Heart Lung Centre Utrecht, University Medical Centre Utrecht, Yalelaan 50, NL-3584 CM Utrecht, Netherlands.
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Detre E, Thomsen MB, Beekman JD, Petersen KU, Vos MA. Decreasing the infusion rate reduces the proarrhythmic risk of NS-7: confirming the relevance of short-term variability of repolarisation in predicting drug-induced torsades de pointes. Br J Pharmacol 2006; 145:397-404. [PMID: 15778734 PMCID: PMC1576153 DOI: 10.1038/sj.bjp.0706203] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
1 The rate of infusion has been suggested to be important for drug-induced torsades de pointes (TdP) arrhythmias. We investigated the repolarisation-prolonging effects and proarrhythmic properties of NS-7, a neuroprotective drug in development, using two different infusion rates. 2 A fast (5 min intravenously (i.v.)) escalating dosing regimen (0.3 and 3.0 mg kg(-1), n=4) of NS-7 was investigated in anaesthetised control dogs in sinus rhythm (SR). This was compared to a slow infusion (60 min i.v.) of one dose (3.0 mg kg(-1), n=4) NS-7. The similar dosing regimens were investigated in anaesthetised dogs with chronic, complete AV block (CAVB), an animal model of TdP (n=6). 3 No electrophysiological effects were seen after 0.3 mg kg(-1) NS-7. Fast infusion of 3.0 mg kg(-1) caused prolongation of repolarisation, for example, heart rate corrected QT interval (QT(c)): in SR: 6+/-1%; in CAVB: 10+/-7%, which was accompanied by TdP in three of six CAVB dogs. No TdP were seen in SR dogs. 4 Slow infusion did not cause TdP in the same CAVB dogs, although NS-7 caused repolarisation to prolong with a similar magnitude (QT(c): 12+/-7%) as in the fast-infusion experiment. 5 Short-term variability (STV) is a novel parameter for the prediction of drug-induced TdP analysing the beat-to-beat variability of repolarisation. STV was only increased after the fast infusion in CAVB dogs (2.6+/-0.3 versus 6.0+/-1.4 ms, P<0.05), while there was no increase (2.1+/-0.2 versus 2.5+/-1.0 ms) after the slow infusion of NS-7. 6 Peak plasma concentrations attained were lower in slow (0.5+/-0.1 microg ml(-1) after 50 min) than in fast-infusion regimen (2.1+/-0.4 microg ml(-1) after 5 min; P<0.05). 7 The results support the conclusion that limiting peak plasma concentration by decreasing the rate of infusion of NS-7 reduces the proarrhythmic risk despite comparable prolongation in repolarisation parameters. The relevance of STV in predicting drug-induced TdP was confirmed.
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Affiliation(s)
- Elke Detre
- Department of Cardiology, Cardiovascular Research Institute Maastricht, Academic Hospital Maastricht, Maastricht, The Netherlands
| | - Morten B Thomsen
- Department of Cardiology, Cardiovascular Research Institute Maastricht, Academic Hospital Maastricht, Maastricht, The Netherlands
- Department of Medical Physiology, Heart Lung Centre Utrecht, University Medical Centre Utrecht, Utrecht, The Netherlands
| | - Jet D Beekman
- Department of Cardiology, Cardiovascular Research Institute Maastricht, Academic Hospital Maastricht, Maastricht, The Netherlands
- Department of Medical Physiology, Heart Lung Centre Utrecht, University Medical Centre Utrecht, Utrecht, The Netherlands
| | | | - Marc A Vos
- Department of Cardiology, Cardiovascular Research Institute Maastricht, Academic Hospital Maastricht, Maastricht, The Netherlands
- Department of Medical Physiology, Heart Lung Centre Utrecht, University Medical Centre Utrecht, Utrecht, The Netherlands
- Author for correspondence:
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Hund TJ, Rudy Y. A role for calcium/calmodulin-dependent protein kinase II in cardiac disease and arrhythmia. Handb Exp Pharmacol 2006:201-20. [PMID: 16610345 DOI: 10.1007/3-540-29715-4_7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
More than 20 years have passed since the discovery that a collection of specific calcium/calmodulin-dependent phosphorylation events is the result of a single multifunctional kinase. Since that time, we have learned a great deal about this multifunctional and ubiquitous kinase, known today as calcium/calmodulin-dependent protein kinase II (CaMKII). CaMKII is interesting not only for its widespread distribution and broad specificity but also for its biophysical properties, most notably its activation by the critical second messenger complex calcium/calmodulin and its autophosphorylating capability. A central role for CaMKII has been identified in regulating a diverse array of fundamental cellular activities. Furthermore, altered CaMKII activity profoundly impacts function in the brain and heart. Recent findings that CaMKII expression in the heart changes during hypertrophy, heart failure, myocardial ischemia, and infarction suggest that CaMKII may be a viable therapeutic target for patients suffering from common forms of heart disease.
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Affiliation(s)
- T J Hund
- Department of Pathology and Immunology, Washington University in Saint Louis School of Medicine, 660 S. Euclid Ave., Campus Box 8118, Saint Louis, MO 63118, USA.
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Abstract
QT interval prolongation is incontrovertibly linked to increased risk of arrhythmias but, paradoxically, QT interval prolongation can also be an effective antiarrhythmic strategy and is in fact the goal of class III antiarrhythmic drugs. This discussion examines the cellular effects of QT interval prolongation and proposes that calmodulin kinase II (CaMKII) is a specific cellular proarrhythmic signal that is activated downstream to QT interval prolongation. Inhibition of CaMKII can prevent cellular arrhythmia surrogates and in vivo arrhythmias linked to excessive action potential prolongation, suggesting that QT interval prolongation alone does not fully account for proarrhythmia. This reasoning points to the conclusion that QT interval modulation and prolongation not only grades cellular Ca2+ entry for cardiac contraction but also has the potential to recruit Ca2+-activated signalling molecules. CaMKII is one of these molecules and CaMKII activity is at least partially responsible for the proarrhythmic consequences of excessive QT interval prolongation.
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Affiliation(s)
- M E Anderson
- Department of Cardiovascular Medicine, Vanderbilt University Medical School, Nashville, TN, USA.
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Viitasalo M, Oikarinen L, Swan H, Glatter KA, Väänänen H, Fodstad H, Chiamvimonvat N, Kontula K, Toivonen L, Scheinman MM. Ratio of late to early T-wave peak amplitude in 24-h electrocardiographic recordings as indicator of symptom history in patients with long-QT Syndrome types 1 and 2. J Am Coll Cardiol 2005; 47:112-20. [PMID: 16386673 DOI: 10.1016/j.jacc.2005.07.068] [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] [Received: 04/16/2005] [Revised: 07/14/2005] [Accepted: 07/25/2005] [Indexed: 10/25/2022]
Abstract
UNLABELLED We reviewed 24-h electrocardiographic recordings from 214 genotyped subjects--97 with long-QT syndrome type 1 (LQT1), 62 with LQT2, and 55 unaffected--to record maximal diurnal amplitude ratios between late and early T-wave peaks. Maximal amplitude ratios between late and early T-wave peaks were higher in symptomatic than in asymptomatic patients both in LQT1 (3.2 +/- 1.0 vs. 2.3 +/- 0.8; p < 0.001) and in LQT2 patients (2.6 +/- 1.0 vs. 1.7 +/- 0.5; p < 0.001). The maximal amplitude ratio between late and early T-wave peaks was independently associated with symptom history in both LQT1 and LQT2 patients. OBJECTIVES We tested the hypothesis that in long-QT syndrome types 1 (LQT1) and 2 (LQT2), the diurnal maximal ratio between late and early T-wave peak amplitudes correlates with a history of symptoms better than QT interval durations. BACKGROUND Genotype and phenotype studies have delineated clinical profiles of the most prevalent LQT1 and LQT2 subtypes of inherited LQT, but prediction of arrhythmia risk remains uncertain, the baseline QTc interval being the best predictor. In experimental long-QT syndrome models, the ratio between late and early T-wave peak amplitude predicts onset of torsade de pointes. METHODS We reviewed 24-h electrocardiographic recordings from 214 genotyped subjects--97 with LQT1, 62 with LQT2, and 55 unaffected-to record maximal amplitude ratios between late and early T-wave peaks by use of a computer-assisted program. RESULTS Maximal amplitude ratios between late and early T-wave peaks were higher in symptomatic than in asymptomatic patients both in LQT1 (3.2 +/- 1.0 vs. 2.3 +/- 0.8; p < 0.001) and LQT2 patients (2.6 +/- 1.0 vs. 1.7 +/- 0.5; p < 0.001). Although the QTc interval also was longer in symptomatic patients, only the maximal amplitude ratio between late and early T-wave peaks was independently associated with symptoms in both LQT1 and LQT2 patients. CONCLUSIONS Maximal diurnal ratio between late and early T-wave peak amplitude improves noninvasive risk assessment both in LQT1 and LQT2 syndromes. We propose this new indicator in clinical evaluation of arrhythmia risk in LQT1 and LQT2.
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Affiliation(s)
- Matti Viitasalo
- Department of Cardiology, Helsinki University Central Hospital, Helsinki, Finland.
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Wilson LD, Said T, Rosenbaum DS. Disease models for elucidation of mechanisms and prediction of drug-induced proarrhythmia. ACTA ACUST UNITED AC 2005. [DOI: 10.1016/j.ddmod.2005.08.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Makaula S, Lochner A, Genade S, Sack MN, Awan MM, Opie LH. H-89, a Non-Specific Inhibitor of Protein Kinase A, Promotes Post-Ischemic Cardiac Contractile Recovery and Reduces Infarct Size. J Cardiovasc Pharmacol 2005; 45:341-7. [PMID: 15772523 DOI: 10.1097/01.fjc.0000156825.80951.14] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Myocardial ischemia is associated with increased production of cyclic adenosine monophosphate (cAMP), with potentially deleterious effects. We hypothesized that the ischemia-induced activation of cAMP-dependent protein kinase A (PKA), could beneficially be inhibited by a PKA-inhibitor N-(2-[p-bromocinnamylamino]ethyl)-5-isoquinoline-sulfonamide (H-89). H-89 when given to isolated perfused rat hearts before 30 minutes of global ischemia-reperfusion improved postischemic function and decreased infarct size. In another series, H-89 administered prior to preconditioning by 10 minutes of transient global ischemia decreased PKA activity (measured at the end of the preconditioning protocol) and augmented postischemic mechanical recovery. H-89 given for 5 minutes before the 10 minutes of transient ischemia further decreased infarct size from 13.4 +/- 1.0% (preconditioning alone) to 7.0 +/- 0.93 (P < 0.01). In a third series, forskolin (0.3 muM, 5 minutes, 10 minutes washout prior to ischemia) increased PKA activity and reduced infarct size. Prior H-89 decreased PKA activity after 5 minutes of forskolin and further reduced infarct size versus forskolin alone. In conclusion, three procedures increased postischemic recovery and reduced infarct size: H-89; preconditioning by transient ischemia; or forskolin as a preconditioning-mimetic. PKA-inhibition by H-89 further decreased infarct size beyond preconditioning or forskolin. Despite the reservation that H-89 could be non-selective in its actions, we propose H-89 as a candidate cardioprotective agent.
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Affiliation(s)
- Siyanda Makaula
- Hatter Institute for Cardiology Research and Servier Heart Failure Laboratory, University of Cape Town Faculty of Health Sciences, South Africa
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Farkas A, Batey AJ, Coker SJ. How to measure electrocardiographic QT interval in the anaesthetized rabbit. J Pharmacol Toxicol Methods 2004; 50:175-85. [PMID: 15519904 DOI: 10.1016/j.vascn.2004.05.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2003] [Accepted: 05/10/2004] [Indexed: 11/18/2022]
Abstract
Many drugs prolong QT or QU intervals [QT(U)] in the electrocardiogram (ECG), and this may be associated with the generation of drug-induced torsades de pointes. Therefore, it is essential to assess the ability of the newly developed drugs to prolong QT(U) interval. For this purpose, both in vivo and in vitro rabbit models are frequently used. However, it is very difficult to locate the end of the QT(U) interval in most rabbit ECGs when repolarisation is delayed, as the shape of the T and U waves may be deformed. In addition, as the heart rate of the rabbit is very high, the T (or U) wave may overlap the P wave or even the QRS complex of the following sinoatrial beat. In these circumstances, application of the "extrapolation method" makes it possible to determine the length of the QT(U) interval. This article describes the extrapolation method, shows ECG examples of typical T and U waves in the anaesthetized rabbit, and makes an attempt to provide a useful guide for researchers to measure reliably and reproducibly the duration of the QT(U) interval in rabbit studies.
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Affiliation(s)
- András Farkas
- Second Department of Internal Medicine and Cardiology Centre, Faculty of Medicine, University of Szeged, 6 Korányi fasor, Szeged H-6720, Hungary.
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