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Zaniboni M. The electrical restitution of the non-propagated cardiac ventricular action potential. Pflugers Arch 2024; 476:9-37. [PMID: 37783868 PMCID: PMC10758374 DOI: 10.1007/s00424-023-02866-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 08/19/2023] [Accepted: 09/21/2023] [Indexed: 10/04/2023]
Abstract
Sudden changes in pacing cycle length are frequently associated with repolarization abnormalities initiating cardiac arrhythmias, and physiologists have long been interested in measuring the likelihood of these events before their manifestation. A marker of repolarization stability has been found in the electrical restitution (ER), the response of the ventricular action potential duration to a pre- or post-mature stimulation, graphically represented by the so-called ER curve. According to the restitution hypothesis (ERH), the slope of this curve provides a quantitative discrimination between stable repolarization and proneness to arrhythmias. ER has been studied at the body surface, whole organ, and tissue level, and ERH has soon become a key reference point in theoretical, clinical, and pharmacological studies concerning arrhythmia development, and, despite criticisms, it is still widely adopted. The ionic mechanism of ER and cellular applications of ERH are covered in the present review. The main criticism on ERH concerns its dependence from the way ER is measured. Over the years, in fact, several different experimental protocols have been established to measure ER, which are also described in this article. In reviewing the state-of-the art on cardiac cellular ER, I have introduced a notation specifying protocols and graphical representations, with the aim of unifying a sometime confusing nomenclature, and providing a physiological tool, better defined in its scope and limitations, to meet the growing expectations of clinical and pharmacological research.
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Affiliation(s)
- Massimiliano Zaniboni
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma (Italy), Parco Area Delle Scienze, 11/A, 43124, Parma, Italy.
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Li F, Qian LL, Wu LD, Zhang ZY, Zhang L, Liu HH, Zhao N, Zhang J, Chen JY, Yang F, Zhang ZY, Wang C, Dang SP, Zhao XX, Li KL, Zhu WQ, Yao Y, Wang RX. Glucose fluctuations aggravated the late sodium current induced ventricular arrhythmias via the activation of ROS/CaMKII pathway. Eur J Pharmacol 2023; 961:176167. [PMID: 37939994 DOI: 10.1016/j.ejphar.2023.176167] [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: 08/18/2023] [Revised: 10/22/2023] [Accepted: 10/26/2023] [Indexed: 11/10/2023]
Abstract
BACKGROUND Recent evidence revealed that glucose fluctuation might be more likely to cause arrhythmia than persistent hyperglycemia, whereas its mechanisms were elusive. We aimed to investigate the effect of glucose fluctuation on the occurrence of ventricular arrhythmia and its mechanism. METHODS Streptozotocin (STZ) induced diabetic rats were randomized to five groups: the controlled blood glucose (C-STZ) group, uncontrolled blood glucose (U-STZ) group, fluctuated blood glucose (GF-STZ) group, and GF-STZ rats with 100 mg/kg Tempol (GF-STZ + Tempol) group or with 5 mg/kg KN93 (GF-STZ + KN93) group. Six weeks later, the susceptibility of ventricular arrhythmias and the electrophysiological dysfunctions of ventricular myocytes were evaluated using electrocardiogram and patch-clamp technique, respectively. The levels of reactive oxygen species (ROS) and oxidized CaMKII (ox-CaMKII) were determined by fluorescence assay and Western blot, respectively. Neonatal rat cardiomyocytes and H9C2 cells in vitro were used to explore the underlying mechanisms. RESULTS The induction rate of ventricular arrhythmias was 10%, 55%, and 90% in C-STZ group, U-STZ group, and GF-STZ group, respectively (P < 0.05). The electrophysiological dysfunctions of ventricular myocytes, including action potential duration at repolarization of 90% (APD90), APD90 short-term variability (APD90-STV), late sodium current (INa-L), early after depolarization (EAD) and delayed after depolarizations (DAD), as well as the levels of ROS and ox-CaMKII, were significantly increased in GF-STZ group. In vivo and ex vivo, inhibition of ROS or ox-CaMKII reversed these effects. Inhibition of INa-L also significantly alleviated the electrophysiological dysfunctions. In vitro, inhibition of ROS increase could significantly decrease the ox-CaMKII activation induced by glucose fluctuations. CONCLUSIONS Glucose fluctuations aggravated the INa-L induced ventricular arrhythmias though the activation of ROS/CaMKII pathway.
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Affiliation(s)
- Feng Li
- Department of Cardiology, The Affiliated Wuxi People's Hospital of Nanjing Medical University, Wuxi People's Hospital, Wuxi Medical Center, Nanjing Medical University, Wuxi, 214023, China
| | - Ling-Ling Qian
- Department of Cardiology, The Affiliated Wuxi People's Hospital of Nanjing Medical University, Wuxi People's Hospital, Wuxi Medical Center, Nanjing Medical University, Wuxi, 214023, China
| | - Li-Da Wu
- Department of Cardiology, The Affiliated Wuxi People's Hospital of Nanjing Medical University, Wuxi People's Hospital, Wuxi Medical Center, Nanjing Medical University, Wuxi, 214023, China
| | - Zhen-Ye Zhang
- Department of Cardiology, The Affiliated Wuxi People's Hospital of Nanjing Medical University, Wuxi People's Hospital, Wuxi Medical Center, Nanjing Medical University, Wuxi, 214023, China
| | - Lei Zhang
- Department of Cardiology, The Affiliated Wuxi People's Hospital of Nanjing Medical University, Wuxi People's Hospital, Wuxi Medical Center, Nanjing Medical University, Wuxi, 214023, China
| | - Huan-Huan Liu
- Wuxi School of Medicine, Jiangnan University, Wuxi, 214122, China
| | - Ning Zhao
- Wuxi School of Medicine, Jiangnan University, Wuxi, 214122, China
| | - Jie Zhang
- Department of Cardiology, The Affiliated Wuxi People's Hospital of Nanjing Medical University, Wuxi People's Hospital, Wuxi Medical Center, Nanjing Medical University, Wuxi, 214023, China
| | - Jia-Yi Chen
- Department of Cardiology, The Affiliated Wuxi People's Hospital of Nanjing Medical University, Wuxi People's Hospital, Wuxi Medical Center, Nanjing Medical University, Wuxi, 214023, China
| | - Fan Yang
- Department of Cardiology, The Affiliated Wuxi People's Hospital of Nanjing Medical University, Wuxi People's Hospital, Wuxi Medical Center, Nanjing Medical University, Wuxi, 214023, China
| | - Zhi-Yuan Zhang
- Department of Cardiology, The Affiliated Wuxi People's Hospital of Nanjing Medical University, Wuxi People's Hospital, Wuxi Medical Center, Nanjing Medical University, Wuxi, 214023, China
| | - Chao Wang
- Department of Cardiology, The Affiliated Wuxi People's Hospital of Nanjing Medical University, Wuxi People's Hospital, Wuxi Medical Center, Nanjing Medical University, Wuxi, 214023, China
| | - Shi-Peng Dang
- Department of Cardiology, The Affiliated Wuxi People's Hospital of Nanjing Medical University, Wuxi People's Hospital, Wuxi Medical Center, Nanjing Medical University, Wuxi, 214023, China
| | - Xiao-Xi Zhao
- Department of Cardiology, The Affiliated Wuxi People's Hospital of Nanjing Medical University, Wuxi People's Hospital, Wuxi Medical Center, Nanjing Medical University, Wuxi, 214023, China
| | - Ku-Lin Li
- Department of Cardiology, The Affiliated Wuxi People's Hospital of Nanjing Medical University, Wuxi People's Hospital, Wuxi Medical Center, Nanjing Medical University, Wuxi, 214023, China
| | - Wen-Qing Zhu
- Department of Cardiology, Zhongshan Hospital, Fudan University, Shanghai Institute of Cardiovascular Disease, Shanghai, China.
| | - Yan Yao
- Department of Cardiology, Fuwai Hospital, Chinese Academy of Medical Sciences-Peking Union Medical College, Beijing, China.
| | - Ru-Xing Wang
- Department of Cardiology, The Affiliated Wuxi People's Hospital of Nanjing Medical University, Wuxi People's Hospital, Wuxi Medical Center, Nanjing Medical University, Wuxi, 214023, China.
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3
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Bersell KR, Yang T, Mosley JD, Glazer AM, Hale AT, Kryshtal DO, Kim K, Steimle JD, Brown JD, Salem JE, Campbell CC, Hong CC, Wells QS, Johnson AN, Short L, Blair MA, Behr ER, Petropoulou E, Jamshidi Y, Benson MD, Keyes MJ, Ngo D, Vasan RS, Yang Q, Gerszten RE, Shaffer C, Parikh S, Sheng Q, Kannankeril PJ, Moskowitz IP, York JD, Wang TJ, Knollmann BC, Roden DM. Transcriptional Dysregulation Underlies Both Monogenic Arrhythmia Syndrome and Common Modifiers of Cardiac Repolarization. Circulation 2023; 147:824-840. [PMID: 36524479 PMCID: PMC9992308 DOI: 10.1161/circulationaha.122.062193] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Accepted: 11/03/2022] [Indexed: 12/23/2022]
Abstract
BACKGROUND Brugada syndrome (BrS) is an inherited arrhythmia syndrome caused by loss-of-function variants in the cardiac sodium channel gene SCN5A (sodium voltage-gated channel alpha subunit 5) in ≈20% of subjects. We identified a family with 4 individuals diagnosed with BrS harboring the rare G145R missense variant in the cardiac transcription factor TBX5 (T-box transcription factor 5) and no SCN5A variant. METHODS We generated induced pluripotent stem cells (iPSCs) from 2 members of a family carrying TBX5-G145R and diagnosed with Brugada syndrome. After differentiation to iPSC-derived cardiomyocytes (iPSC-CMs), electrophysiologic characteristics were assessed by voltage- and current-clamp experiments (n=9 to 21 cells per group) and transcriptional differences by RNA sequencing (n=3 samples per group), and compared with iPSC-CMs in which G145R was corrected by CRISPR/Cas9 approaches. The role of platelet-derived growth factor (PDGF)/phosphoinositide 3-kinase (PI3K) pathway was elucidated by small molecule perturbation. The rate-corrected QT (QTc) interval association with serum PDGF was tested in the Framingham Heart Study cohort (n=1893 individuals). RESULTS TBX5-G145R reduced transcriptional activity and caused multiple electrophysiologic abnormalities, including decreased peak and enhanced "late" cardiac sodium current (INa), which were entirely corrected by editing G145R to wild-type. Transcriptional profiling and functional assays in genome-unedited and -edited iPSC-CMs showed direct SCN5A down-regulation caused decreased peak INa, and that reduced PDGF receptor (PDGFRA [platelet-derived growth factor receptor α]) expression and blunted signal transduction to PI3K was implicated in enhanced late INa. Tbx5 regulation of the PDGF axis increased arrhythmia risk due to disruption of PDGF signaling and was conserved in murine model systems. PDGF receptor blockade markedly prolonged normal iPSC-CM action potentials and plasma levels of PDGF in the Framingham Heart Study were inversely correlated with the QTc interval (P<0.001). CONCLUSIONS These results not only establish decreased SCN5A transcription by the TBX5 variant as a cause of BrS, but also reveal a new general transcriptional mechanism of arrhythmogenesis of enhanced late sodium current caused by reduced PDGF receptor-mediated PI3K signaling.
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Affiliation(s)
- Kevin R Bersell
- Departments of Pharmacology (K.R.B., A.M.G., D.O.K., K.K., J-E.S., C.C.C., Q.S.W., S.P., B.C.K., D.M.R.), Vanderbilt University, Nashville, TN
| | - Tao Yang
- Medicine (T.Y., J.D.M., J.D.B., J-E.S., Q.S.W., L.S., M.A.B., C.S., T.J.W., B.C.K., D.M.R.), Vanderbilt University, Nashville, TN
| | - Jonathan D Mosley
- Departments of Pharmacology (K.R.B., A.M.G., D.O.K., K.K., J-E.S., C.C.C., Q.S.W., S.P., B.C.K., D.M.R.), Vanderbilt University, Nashville, TN
| | - Andrew M Glazer
- Departments of Pharmacology (K.R.B., A.M.G., D.O.K., K.K., J-E.S., C.C.C., Q.S.W., S.P., B.C.K., D.M.R.), Vanderbilt University, Nashville, TN
| | - Andrew T Hale
- Biochemistry (A.T.H., J.D.Y.), Vanderbilt University, Nashville, TN
| | - Dmytro O Kryshtal
- Departments of Pharmacology (K.R.B., A.M.G., D.O.K., K.K., J-E.S., C.C.C., Q.S.W., S.P., B.C.K., D.M.R.), Vanderbilt University, Nashville, TN
| | - Kyungsoo Kim
- Departments of Pharmacology (K.R.B., A.M.G., D.O.K., K.K., J-E.S., C.C.C., Q.S.W., S.P., B.C.K., D.M.R.), Vanderbilt University, Nashville, TN
| | - Jeffrey D Steimle
- Departments of Pediatrics, Pathology, and Human Genetics, University of Chicago, IL (J.D.S., I.P.M.)
| | - Jonathan D Brown
- Medicine (T.Y., J.D.M., J.D.B., J-E.S., Q.S.W., L.S., M.A.B., C.S., T.J.W., B.C.K., D.M.R.), Vanderbilt University, Nashville, TN
| | - Joe-Elie Salem
- Departments of Pharmacology (K.R.B., A.M.G., D.O.K., K.K., J-E.S., C.C.C., Q.S.W., S.P., B.C.K., D.M.R.), Vanderbilt University, Nashville, TN
- Medicine (T.Y., J.D.M., J.D.B., J-E.S., Q.S.W., L.S., M.A.B., C.S., T.J.W., B.C.K., D.M.R.), Vanderbilt University, Nashville, TN
- Assistance Publique - Hôpitaux de Paris, Pitié-Salpêtrière Hospital, Department of Pharmacology, CIC-1901, Sorbonne University, Paris, France (J-E.S.)
- Sorbonne Universités, UPMC Univ Paris 06, Faculty of Medicine, France (J-E.S.)
| | - Courtney C Campbell
- Departments of Pharmacology (K.R.B., A.M.G., D.O.K., K.K., J-E.S., C.C.C., Q.S.W., S.P., B.C.K., D.M.R.), Vanderbilt University, Nashville, TN
| | - Charles C Hong
- Department of Medicine, University of Maryland School of Medicine, Baltimore (C.C.H.)
| | - Quinn S Wells
- Departments of Pharmacology (K.R.B., A.M.G., D.O.K., K.K., J-E.S., C.C.C., Q.S.W., S.P., B.C.K., D.M.R.), Vanderbilt University, Nashville, TN
- Medicine (T.Y., J.D.M., J.D.B., J-E.S., Q.S.W., L.S., M.A.B., C.S., T.J.W., B.C.K., D.M.R.), Vanderbilt University, Nashville, TN
- Biomedical Informatics (Q.S.W., D.M.R.), Vanderbilt University, Nashville, TN
| | - Amanda N Johnson
- Molecular Physiology and Biophysics (A.N.J.), Vanderbilt University, Nashville, TN
| | - Laura Short
- Medicine (T.Y., J.D.M., J.D.B., J-E.S., Q.S.W., L.S., M.A.B., C.S., T.J.W., B.C.K., D.M.R.), Vanderbilt University, Nashville, TN
| | - Marcia A Blair
- Medicine (T.Y., J.D.M., J.D.B., J-E.S., Q.S.W., L.S., M.A.B., C.S., T.J.W., B.C.K., D.M.R.), Vanderbilt University, Nashville, TN
| | | | - Evmorfia Petropoulou
- Cardiology Clinical Academic Group, Molecular and Clinical Sciences Institute, St George's, University of London and St George's University Hospitals National Health Service Foundation Trust, London, UK (E.P., Y.J.)
| | - Yalda Jamshidi
- Cardiology Clinical Academic Group, Molecular and Clinical Sciences Institute, St George's, University of London and St George's University Hospitals National Health Service Foundation Trust, London, UK (E.P., Y.J.)
| | - Mark D Benson
- Cardiovascular Research Center (E.J.B., M.D.B., M.J.K., R.E.G.), Beth Israel Deaconess Hospital, Boston, MA
- Division of Cardiovascular Medicine, Brigham and Women's Hospital, Boston, MA (M.D.B.)
| | - Michelle J Keyes
- Cardiovascular Research Center (E.J.B., M.D.B., M.J.K., R.E.G.), Beth Israel Deaconess Hospital, Boston, MA
| | - Debby Ngo
- Division of Pulmonary and Cardiovascular Medicine (D.N., R.E.G.), Beth Israel Deaconess Hospital, Boston, MA
| | | | - Qiong Yang
- Boston University School of Medicine, MA (R.S.V., Q.Y.)
| | - Robert E Gerszten
- Cardiovascular Research Center (E.J.B., M.D.B., M.J.K., R.E.G.), Beth Israel Deaconess Hospital, Boston, MA
- Division of Pulmonary and Cardiovascular Medicine (D.N., R.E.G.), Beth Israel Deaconess Hospital, Boston, MA
| | - Christian Shaffer
- Medicine (T.Y., J.D.M., J.D.B., J-E.S., Q.S.W., L.S., M.A.B., C.S., T.J.W., B.C.K., D.M.R.), Vanderbilt University, Nashville, TN
| | - Shan Parikh
- Departments of Pharmacology (K.R.B., A.M.G., D.O.K., K.K., J-E.S., C.C.C., Q.S.W., S.P., B.C.K., D.M.R.), Vanderbilt University, Nashville, TN
| | | | | | - Ivan P Moskowitz
- Departments of Pediatrics, Pathology, and Human Genetics, University of Chicago, IL (J.D.S., I.P.M.)
| | - John D York
- Biochemistry (A.T.H., J.D.Y.), Vanderbilt University, Nashville, TN
| | - Thomas J Wang
- Medicine (T.Y., J.D.M., J.D.B., J-E.S., Q.S.W., L.S., M.A.B., C.S., T.J.W., B.C.K., D.M.R.), Vanderbilt University, Nashville, TN
| | - Bjorn C Knollmann
- Departments of Pharmacology (K.R.B., A.M.G., D.O.K., K.K., J-E.S., C.C.C., Q.S.W., S.P., B.C.K., D.M.R.), Vanderbilt University, Nashville, TN
- Medicine (T.Y., J.D.M., J.D.B., J-E.S., Q.S.W., L.S., M.A.B., C.S., T.J.W., B.C.K., D.M.R.), Vanderbilt University, Nashville, TN
| | - Dan M Roden
- Departments of Pharmacology (K.R.B., A.M.G., D.O.K., K.K., J-E.S., C.C.C., Q.S.W., S.P., B.C.K., D.M.R.), Vanderbilt University, Nashville, TN
- Medicine (T.Y., J.D.M., J.D.B., J-E.S., Q.S.W., L.S., M.A.B., C.S., T.J.W., B.C.K., D.M.R.), Vanderbilt University, Nashville, TN
- Biomedical Informatics (Q.S.W., D.M.R.), Vanderbilt University, Nashville, TN
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4
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Ko TH, Jeong D, Yu B, Song JE, Le QA, Woo SH, Choi JI. Inhibition of late sodium current via PI3K/Akt signaling prevents cellular remodeling in tachypacing-induced HL-1 atrial myocytes. Pflugers Arch 2023; 475:217-231. [PMID: 36274100 PMCID: PMC9849166 DOI: 10.1007/s00424-022-02754-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 07/04/2022] [Accepted: 09/23/2022] [Indexed: 02/01/2023]
Abstract
An aberrant late sodium current (INa,Late) caused by a mutation in the cardiac sodium channel (Nav1.5) has emerged as a contributor to electrical remodeling that causes susceptibility to atrial fibrillation (AF). Although downregulation of phosphoinositide 3-kinase (PI3K)/Akt signaling is associated with AF, the molecular mechanisms underlying the negative regulation of INa,Late in AF remain unclear, and potential therapeutic approaches are needed. In this work, we constructed a tachypacing-induced cellular model of AF by exposing HL-1 myocytes to rapid electrical stimulation (1.5 V/cm, 4 ms, 10 Hz) for 6 h. Then, we gathered data using confocal Ca2+ imaging, immunofluorescence, patch-clamp recordings, and immunoblots. The tachypacing cells displayed irregular Ca2+ release, delayed afterdepolarization, prolonged action potential duration, and reduced PI3K/Akt signaling compared with controls. Those detrimental effects were related to increased INa,Late and were significantly mediated by treatment with the INa,Late blocker ranolazine. Furthermore, decreased PI3K/Akt signaling via PI3K inhibition increased INa,Late and subsequent aberrant myocyte excitability, which were abolished by INa,Late inhibition, suggesting that PI3K/Akt signaling is responsible for regulating pathogenic INa,Late. These results indicate that PI3K/Akt signaling is critical for regulating INa,Late and electrical remodeling, supporting the use of PI3K/Akt-mediated INa,Late as a therapeutic target for AF.
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Affiliation(s)
- Tae Hee Ko
- Division of Cardiology, Department of Internal Medicine, Korea University College of Medicine and Korea University Medical Centre, 73, Goryeodae-ro, Seongbuk-gu, Seoul, 02841 Republic of Korea ,Ion Channel Research Unit, Cardiovascular Research Institute, Korea University, Seoul, Republic of Korea
| | - Daun Jeong
- Division of Cardiology, Department of Internal Medicine, Korea University College of Medicine and Korea University Medical Centre, 73, Goryeodae-ro, Seongbuk-gu, Seoul, 02841 Republic of Korea
| | - Byeongil Yu
- Division of Cardiology, Department of Internal Medicine, Korea University College of Medicine and Korea University Medical Centre, 73, Goryeodae-ro, Seongbuk-gu, Seoul, 02841 Republic of Korea
| | - Ji Eun Song
- Division of Cardiology, Department of Internal Medicine, Korea University College of Medicine and Korea University Medical Centre, 73, Goryeodae-ro, Seongbuk-gu, Seoul, 02841 Republic of Korea
| | - Qui Anh Le
- Laboratory of Pathophysiology, College of Pharmacy, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon, 34134 Republic of Korea
| | - Sun-Hee Woo
- Laboratory of Pathophysiology, College of Pharmacy, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon, 34134 Republic of Korea
| | - Jong-Il Choi
- Division of Cardiology, Department of Internal Medicine, Korea University College of Medicine and Korea University Medical Centre, 73, Goryeodae-ro, Seongbuk-gu, Seoul, 02841 Republic of Korea ,Ion Channel Research Unit, Cardiovascular Research Institute, Korea University, Seoul, Republic of Korea
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5
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Kashiwa A, Makiyama T, Kohjitani H, Maurissen TL, Ishikawa T, Yamamoto Y, Wuriyanghai Y, Gao J, Huang H, Imamura T, Aizawa T, Nishikawa M, Chonabayashi K, Mishima H, Ohno S, Toyoda F, Sato S, Yoshiura KI, Takahashi K, Yoshida Y, Woltjen K, Horie M, Makita N, Kimura T. Disrupted Ca V1.2 selectivity causes overlapping long QT and Brugada syndrome phenotypes in the CACNA1C-E1115K iPS cell model. Heart Rhythm 2023; 20:89-99. [PMID: 36007726 DOI: 10.1016/j.hrthm.2022.08.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 07/22/2022] [Accepted: 08/16/2022] [Indexed: 01/28/2023]
Abstract
BACKGROUND A missense mutation in the α1c subunit of voltage-gated L-type Ca2+ channel-coding CACNA1C-E1115K, located in the Ca2+ selectivity site, causes a variety of arrhythmogenic phenotypes. OBJECTIVE We aimed to investigate the electrophysiological features and pathophysiological mechanisms of CACNA1C-E1115K in patient-specific induced pluripotent stem cell (iPSC)-derived cardiomyocytes (CMs). METHODS We generated iPSCs from a patient carrying heterozygous CACNA1C-E1115K with overlapping phenotypes of long QT syndrome, Brugada syndrome, and mild cardiac dysfunction. Electrophysiological properties were investigated using iPSC-CMs. We used iPSCs from a healthy individual and an isogenic iPSC line corrected using CRISPR-Cas9-mediated gene editing as controls. A mathematical E1115K-CM model was developed using a human ventricular cell model. RESULTS Patch-clamp analysis revealed that E1115K-iPSC-CMs exhibited reduced peak Ca2+ current density and impaired Ca2+ selectivity with an increased permeability to monovalent cations. Consequently, E1115K-iPSC-CMs showed decreased action potential plateau amplitude, longer action potential duration (APD), and a higher frequency of early afterdepolarization compared with controls. In optical recordings examining the antiarrhythmic drug effect, late Na+ channel current (INaL) inhibitors (mexiletine and GS-458967) shortened APDs specifically in E1115K-iPSC-CMs. The AP-clamp using a voltage command obtained from E1115K-iPSC-CMs with lower action potential plateau amplitude and longer APD confirmed the upregulation of INaL. An in silico study recapitulated the in vitro electrophysiological properties. CONCLUSION Our iPSC-based analysis in CACNA1C-E1115K with disrupted CaV1.2 selectivity demonstrated that the aberrant currents through the mutant channels carried by monovalent cations resulted in specific action potential changes, which increased endogenous INaL, thereby synergistically contributing to the arrhythmogenic phenotype.
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Affiliation(s)
- Asami Kashiwa
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Takeru Makiyama
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan; Department of Community Medicine Supporting System, Kyoto University Graduate School of Medicine, Kyoto, Japan.
| | - Hirohiko Kohjitani
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan; Department of Biomedical Data Intelligence, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Thomas L Maurissen
- Department of Life Science Frontiers, Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan
| | - Taisuke Ishikawa
- Omics Research Center, National Cerebral and Cardiovascular Center, Suita, Japan
| | - Yuta Yamamoto
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Yimin Wuriyanghai
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Jingshan Gao
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Hai Huang
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Tomohiko Imamura
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Takanori Aizawa
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Misato Nishikawa
- Department of Cell Growth and Differentiation, Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan
| | - Kazuhisa Chonabayashi
- Department of Cell Growth and Differentiation, Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan; Department of Hematology and Oncology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Hiroyuki Mishima
- Department of Human Genetics, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
| | - Seiko Ohno
- Department of Bioscience and Genetics, National Cerebral and Cardiovascular Center, Suita, Japan
| | - Futoshi Toyoda
- Department of Physiology, Shiga University of Medical Science, Otsu, Japan
| | - Seiichi Sato
- Division of Pediatric Cardiology & Pediatric Intensive Care Unit, Okinawa Prefectural Nanbu Medical Center & Children's Medical Center, Haebaru, Japan
| | - Koh-Ichiro Yoshiura
- Department of Human Genetics, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
| | | | - Yoshinori Yoshida
- Department of Cell Growth and Differentiation, Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan
| | - Knut Woltjen
- Department of Life Science Frontiers, Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan
| | - Minoru Horie
- Department of Cardiovascular Medicine, Shiga University of Medical Science, Otsu, Japan
| | - Naomasa Makita
- Omics Research Center, National Cerebral and Cardiovascular Center, Suita, Japan
| | - Takeshi Kimura
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan
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Qauli AI, Yoo Y, Marcellinus A, Lim KM. Verification of the Efficacy of Mexiletine Treatment for the A1656D Mutation on Downgrading Reentrant Tachycardia Using a 3D Cardiac Electrophysiological Model. Bioengineering (Basel) 2022; 9:531. [PMID: 36290499 PMCID: PMC9598628 DOI: 10.3390/bioengineering9100531] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 10/03/2022] [Accepted: 10/05/2022] [Indexed: 10/21/2023] Open
Abstract
The SCN5A mutations have been long associated with long QT variant 3 (LQT3). Recent experimental and computation studies have reported that mexiletine effectively treats LQT3 patients associated with the A1656D mutation. However, they have primarily focused on cellular level evaluations and have only looked at the effects of mexiletine on action potential duration (APD) or QT interval reduction. We further investigated mexiletine's effects on cardiac cells through simulations of single-cell (behavior of alternant occurrence) and 3D (with and without mexiletine). We discovered that mexiletine could shorten the cell's APD and change the alternant's occurrence to a shorter basic cycle length (BCL) between 350 and 420 ms. The alternant also appeared at a normal heart rate under the A1656D mutation. Furthermore, the 3D ventricle simulations revealed that mexiletine could reduce the likelihood of a greater spiral wave breakup in the A1656D mutant condition by minimizing the appearance of rotors. In conclusion, we found that mexiletine could provide extra safety features during therapy for LQT3 patients because it can change the alternant occurrence from a normal to a faster heart rate, and it reduces the chance of a spiral wave breakup. Therefore, these findings emphasize the promising efficacy of mexiletine in treating LQT3 patients under the A1656D mutation.
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Affiliation(s)
- Ali Ikhsanul Qauli
- Department of IT Convergence Engineering, Kumoh National Institute of Technology, Gumi 39177, Korea
- Robotics and Artificial Intelligence Engineering, Faculty of Advanced Technology and Multidiscipline, Universitas Airlangga, Surabaya 60115, Jawa Timur, Indonesia
| | - Yedam Yoo
- Department of IT Convergence Engineering, Kumoh National Institute of Technology, Gumi 39177, Korea
| | - Aroli Marcellinus
- Department of IT Convergence Engineering, Kumoh National Institute of Technology, Gumi 39177, Korea
| | - Ki Moo Lim
- Department of IT Convergence Engineering, Kumoh National Institute of Technology, Gumi 39177, Korea
- Department of Medical IT Convergence Engineering, Kumoh National Institute of Technology, Gumi 39253, Korea
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7
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Guo S, Xue YJ, Zhu X, Yang B, Zhou CZ. Effects and pharmacological mechanism of Zhigancao Decoction on electrical and structural remodeling of the atrium of rabbits induced by rapid atrial pacing. J Interv Card Electrophysiol 2022; 66:597-609. [PMID: 36098833 DOI: 10.1007/s10840-022-01356-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Accepted: 08/20/2022] [Indexed: 11/30/2022]
Abstract
BACKGROUND Zhigancao decoction (ZD) has a long history in China as a traditional Chinese medicine compound for the treatment of tachyarrhythmias. This study mainly explored the pharmacological mechanism of Zhigancao Decoction in preventing atrial fibrillation by altering the electrical and structural remodeling of the atrial in rabbits. METHODS In total, 30 male New Zealand white rabbits were randomly divided into 3 groups (ten rabbits for each). The first group was sham-operated (control group). The second group was intervened by the rapid right atrium pacing (RAP) to induce atrial fibrillation (AF group), while the third group was given ZD gavage and RAP (AF + ZD group). All rabbits were anesthetized before two monophasic action potential (MAP) catheters were sequentially inserted into the right atrium. After 8 h of rapid right atrial pacing, the electrophysiological indexes and the induction rate of atrial fibrillation were observed in the three groups of rabbits, and the left atrial myocardium samples were taken to observe the ultrastructure. Single atrial myocytes were separated by enzymolysis, and the L-type calcium current (ICa-L) of atrial myocytes in different experimental groups was observed by whole-cell patch clamp technique. The fluorescence intensity of Ca2+ in atrial myocytes was observed after Fluo-3/AM fluorescent staining. The main components of ZD were identified by liquid chromatography-mass spectrometry-mass spectrometry (LC-MS/MS) method. RESULTS Compared with the AF group, the maximum ascent rate (Max dV/dt) and plateau potential were significantly reduced in the ZD group, the action potential duration at 10% and 20% (APD10, APD20) were significantly shortened (P < 0.01), action potential duration at 50%, 70%, and 90% (APD50, APD70, APD90) were significantly prolonged, and atrial effective refractory period (AERP) was significantly prolonged (P < 0.01) in the ZD group. In the ZD group, the ICa-L amplitudes of rabbit atrial myocytes under each clamping voltage were significantly smaller than those in the AF group (P < 0.01) and the control group (P < 0.05). The Ca2+ fluorescence intensity in the rabbit atrial myocytes in the ZD group was significantly weaker than that in the AF group (P < 0.01) and the control group (P < 0.05). Electron microscopy displayed that the control group had neatly arranged atrial tissue myofilaments and intact mitochondria. However, the ultrastructural damage of the AF group was severe compared with that of the ZD group. LC-MS/MS analysis confirmed that ZD contained several antiarrhythmic compounds including ginsenoside, isoliensinine, catalpol, glycyrrhizinate and hesperetin. CONCLUSION Rapid atrial pacing (RAP) could cause the electrical and structural remodeling of rabbit atrial myocytes. ZD might reverse the atrial electrical remodeling but could have little effect on structural remodeling, which might be the mechanism of ZD treatment on atrial fibrillation.
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Affiliation(s)
- Sheng Guo
- Hubei University of Chinese Medicine, Wuhan, 430065, Hubei, China
| | - Yao-Jun Xue
- Hubei University of Chinese Medicine, Wuhan, 430065, Hubei, China
| | - Xue Zhu
- Hubei University of Chinese Medicine, Wuhan, 430065, Hubei, China
| | - Bo Yang
- Hubei University of Chinese Medicine, Wuhan, 430065, Hubei, China. .,Department of Cardiology, Hubei Provincial Hospital of Traditional Chinese Medicine, Wuhan, 430061, Hubei, China.
| | - Cheng-Zhi Zhou
- Department of Cardiology, Hubei Provincial Hospital of Traditional Chinese Medicine, Wuhan, 430061, Hubei, China
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Discussion on Repolarization Reserve between Patients with Coronary Heart Disease and Normal Controls. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2022; 2022:7944969. [PMID: 36035296 PMCID: PMC9410869 DOI: 10.1155/2022/7944969] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 07/20/2022] [Accepted: 07/29/2022] [Indexed: 11/17/2022]
Abstract
Objective To investigate the repolarization reserve of normal controls (NCs) and patients with coronary heart disease (CHD). Methods From January 1st, 2010 to December 31st, 2018, 200 age- and gender-matched inpatients in the Second Hospital of Shanxi Medical University and Heji Hospital Affiliated to Changzhi Medical College were selected for treadmill exercise test (TET), including 67 patients in the myocardial ischemia group, 66 patients in the suspected myocardial ischemia group, and 67 patients in the normal control group. Coronary angiography (CAG) was performed on 49 of 133 patients in the myocardial ischemia group and the suspected myocardial ischemia group, and 9 positives and 40 negatives were identified. The heart rate (HR) and QT interval of TET examiners before exercise, during exercise (90 beats/min, 120 beats/min, maximum HR), and in the recovery period (1 minute and 3 minutes after exercise) were reviewed, and QTc values were calculated after being corrected by BaZett's. Results The mean QTc values in NCs were all below 452 ms, before exercise, during exercise (90 beats/min, 120 beats/min and maximum HR), and during the recovery period (1 minute and 3 minutes after exercise). The comparison results of the RR interval between the two groups revealed P > 0.05, indicating no statistical significance. Significant differences were present when comparing the QT intervals when the HRs were 90 beats/minute and 120 beats/minute during exercise (P < 0.05). And comparing the QTc values, it was found that the QTc values during different exercise periods were statistically different between groups (P < 0.05). Conclusions NCs have good repolarization reserve. CAG can confirm true myocardial ischemia patients (i.e., patients with CHD) among myocardial ischemia and suspected myocardial ischemia patients screened by TET. Patients with positive CAG have poor repolarization reserve as QT interval represents ventricular repolarization adaptability.
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9
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Kawakami S, Kambayashi R, Takada K, Aimoto M, Nagasawa Y, Takahara A. Role of cardiac α1-adrenoreceptors for the torsadogenic action of IKr blocker nifekalant in the anesthetized atrioventricular block rabbit. J Pharmacol Sci 2022; 150:67-73. [DOI: 10.1016/j.jphs.2022.07.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 06/30/2022] [Accepted: 07/19/2022] [Indexed: 10/16/2022] Open
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Champéroux P, Fares R, Bastogne T, Richard S, Le Guennec JY, Thireau J. Contribution of hemodynamic side effects and associated autonomic reflexes to ventricular arrhythmias triggering by torsadogenic hERG blocking drugs. Br J Pharmacol 2022; 179:4549-4562. [PMID: 35751378 PMCID: PMC9543494 DOI: 10.1111/bph.15905] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 05/16/2022] [Accepted: 06/01/2022] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND AND PURPOSES Several hERG blocking drugs known for their propensity to trigger Torsades de Pointes (TdP) were reported to induce a sympatho-vagal coactivation and to enhance High Frequency heart rate (HFHR) and QT oscillations (HFQT) from telemetric data. The present work aims to characterise the underlying mechanism(s) leading to these autonomic changes. EXPERIMENTAL APPROACH Effects of 15 torsadogenic hERG blocking drugs (astemizole, chlorpromazine, cisapride, droperidol, ibutilide, dofetilide, haloperidol, moxifloxacin, pimozide, quinidine, risperidone, sotalol, sertindole, terfenadine, thioridazine) were assessed by telemetry in beagle dogs. Hemodynamic effects on diastolic and systolic arterial pressure were analysed from the first doses causing QTc prolongation and/or HFQT oscillations enhancement. Autonomic control changes were analysed with the High Frequency Autonomic Modulation (HFAM) model. KEY RESULTS Except moxifloxacin and quinidine, all torsadogenic hERG blockers induced parasympathetic activation or sympatho-vagal coactivation combined with enhancement of HFQT oscillations. These autonomic effects result from reflex compensatory mechanisms in response to mild hemodynamic side effects. These hemodynamic mechanisms were characterised by transient HR acceleration during HF oscillations. A phenomenon of concealed QT prolongation was unmasked for several torsadogenic hERG blockers under β-adrenoceptors blockade by atenolol. Resulting enhancement of HFQT oscillations was shown to contribute directly to triggering of dofetilide induced ventricular arrhythmias. CONCLUSIONS AND IMPLICATIONS This work supports for the first time a contribution of hemodynamic side properties to ventricular arrhythmias triggering by torsadogenic hERG blocking drugs. These hemodynamic side effects may constitute a second component of their arrhythmic profile acting as a trigger alongside their intrinsic arrhythmogenic electrophysiological properties.
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Affiliation(s)
| | - Raafat Fares
- ERBC France, Chemin de Montifault, Baugy, France
| | - Thierry Bastogne
- CRAN CNRS UMR 7039, Université de Lorraine, Vandœuvre-lès-Nancy, France
| | | | - Jean-Yves Le Guennec
- Laboratoire PHYMEDEXP, Université de Montpellier, INSERM, CNRS, Montpellier cedex, France
| | - Jérôme Thireau
- Laboratoire PHYMEDEXP, Université de Montpellier, INSERM, CNRS, Montpellier cedex, France
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Ranolazine: An Old Drug with Emerging Potential; Lessons from Pre-Clinical and Clinical Investigations for Possible Repositioning. Pharmaceuticals (Basel) 2021; 15:ph15010031. [PMID: 35056088 PMCID: PMC8777683 DOI: 10.3390/ph15010031] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 12/16/2021] [Accepted: 12/20/2021] [Indexed: 02/07/2023] Open
Abstract
Ischemic heart disease is a significant public health problem with high mortality and morbidity. Extensive scientific investigations from basic sciences to clinics revealed multilevel alterations from metabolic imbalance, altered electrophysiology, and defective Ca2+/Na+ homeostasis leading to lethal arrhythmias. Despite the recent identification of numerous molecular targets with potential therapeutic interest, a pragmatic observation on the current pharmacological R&D output confirms the lack of new therapeutic offers to patients. By contrast, from recent trials, molecules initially developed for other fields of application have shown cardiovascular benefits, as illustrated with some anti-diabetic agents, regardless of the presence or absence of diabetes, emphasizing the clear advantage of “old” drug repositioning. Ranolazine is approved as an antianginal agent and has a favorable overall safety profile. This drug, developed initially as a metabolic modulator, was also identified as an inhibitor of the cardiac late Na+ current, although it also blocks other ionic currents, including the hERG/Ikr K+ current. The latter actions have been involved in this drug’s antiarrhythmic effects, both on supraventricular and ventricular arrhythmias (VA). However, despite initial enthusiasm and promising development in the cardiovascular field, ranolazine is only authorized as a second-line treatment in patients with chronic angina pectoris, notwithstanding its antiarrhythmic properties. A plausible reason for this is the apparent difficulty in linking the clinical benefits to the multiple molecular actions of this drug. Here, we review ranolazine’s experimental and clinical knowledge on cardiac metabolism and arrhythmias. We also highlight advances in understanding novel effects on neurons, the vascular system, skeletal muscles, blood sugar control, and cancer, which may open the way to reposition this “old” drug alone or in combination with other medications.
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12
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Kistamás K, Hézső T, Horváth B, Nánási PP. Late sodium current and calcium homeostasis in arrhythmogenesis. Channels (Austin) 2021; 15:1-19. [PMID: 33258400 PMCID: PMC7757849 DOI: 10.1080/19336950.2020.1854986] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 10/26/2020] [Accepted: 11/19/2020] [Indexed: 12/19/2022] Open
Abstract
The cardiac late sodium current (INa,late) is the small sustained component of the sodium current active during the plateau phase of the action potential. Several studies demonstrated that augmentation of the current can lead to cardiac arrhythmias; therefore, INa,late is considered as a promising antiarrhythmic target. Fundamentally, enlarged INa,late increases Na+ influx into the cell, which, in turn, is converted to elevated intracellular Ca2+ concentration through the Na+/Ca2+ exchanger. The excessive Ca2+ load is known to be proarrhythmic. This review describes the behavior of the voltage-gated Na+ channels generating INa,late in health and disease and aims to discuss the physiology and pathophysiology of Na+ and Ca2+ homeostasis in context with the enhanced INa,late demonstrating also the currently accessible antiarrhythmic choices.
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Affiliation(s)
- Kornél Kistamás
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Tamás Hézső
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Balázs Horváth
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Péter P Nánási
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- Department of Dental Physiology, Faculty of Dentistry, University of Debrecen, Debrecen, Hungary
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Jæger KH, Edwards AG, Giles WR, Tveito A. A computational method for identifying an optimal combination of existing drugs to repair the action potentials of SQT1 ventricular myocytes. PLoS Comput Biol 2021; 17:e1009233. [PMID: 34383746 PMCID: PMC8360568 DOI: 10.1371/journal.pcbi.1009233] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 07/01/2021] [Indexed: 01/26/2023] Open
Abstract
Mutations are known to cause perturbations in essential functional features of integral membrane proteins, including ion channels. Even restricted or point mutations can result in substantially changed properties of ion currents. The additive effect of these alterations for a specific ion channel can result in significantly changed properties of the action potential (AP). Both AP shortening and AP prolongation can result from known mutations, and the consequences can be life-threatening. Here, we present a computational method for identifying new drugs utilizing combinations of existing drugs. Based on the knowledge of theoretical effects of existing drugs on individual ion currents, our aim is to compute optimal combinations that can ‘repair’ the mutant AP waveforms so that the baseline AP-properties are restored. More specifically, we compute optimal, combined, drug concentrations such that the waveforms of the transmembrane potential and the cytosolic calcium concentration of the mutant cardiomyocytes (CMs) becomes as similar as possible to their wild type counterparts after the drug has been applied. In order to demonstrate the utility of this method, we address the question of computing an optimal drug for the short QT syndrome type 1 (SQT1). For the SQT1 mutation N588K, there are available data sets that describe the effect of various drugs on the mutated K+ channel. These published findings are the basis for our computational analysis which can identify optimal compounds in the sense that the AP of the mutant CMs resembles essential biomarkers of the wild type CMs. Using recently developed insights regarding electrophysiological properties among myocytes from different species, we compute optimal drug combinations for hiPSC-CMs, rabbit ventricular CMs and adult human ventricular CMs with the SQT1 mutation. Since the ‘composition’ of ion channels that form the AP is different for the three types of myocytes under consideration, so is the composition of the optimal drug. Poly-pharmacology (using multiple drugs to treat disease) has been proposed for improving cardiac anti-arrhythmic therapy for at least two decades. However, the specific arrhythmia contexts in which polytherapy is likely to be both safe and effective have remained elusive. Type 1 short QT syndrome (SQT1) is a rare form of cardiac arrhythmia that results from mutations to the human Ether-á-go-go Related Gene (hERG) potassium channel. Functionally, these mutations are remarkably consistent in that they permit the channel to open earlier during each heart beat. While hundreds of compounds are known to inhibit hERG channels, the specific effect of SQT1 mutations that allows for early channel opening also limits the ability of most of those compounds to correct SQT1 dysfunction. Here, we have applied a suite of ventricular cardiomyocyte computational models to ask whether polytherapy may offer a more effective therapeutic strategy in SQT1, and if so, what the likely characteristics of that strategy are. Our analyses suggest that simultaneous induction of late sodium current and partial hERG blockade offers a promising strategy. While no activators of late sodium current have been clinically approved, several experimental compounds are available and may provide a basis for interrogating this strategy. The method presented here can be used to compute optimal drug combinations provided that the effect of each drug on every relevant ion channel is known.
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MESH Headings
- Action Potentials/drug effects
- Amino Acid Substitution
- Animals
- Anti-Arrhythmia Agents/administration & dosage
- Arrhythmias, Cardiac/drug therapy
- Arrhythmias, Cardiac/genetics
- Arrhythmias, Cardiac/physiopathology
- Computational Biology
- Drug Combinations
- Drug Design
- Drug Therapy, Combination/methods
- ERG1 Potassium Channel/drug effects
- ERG1 Potassium Channel/genetics
- ERG1 Potassium Channel/physiology
- Heart Conduction System/abnormalities
- Heart Conduction System/physiopathology
- Heart Defects, Congenital/drug therapy
- Heart Defects, Congenital/genetics
- Heart Defects, Congenital/physiopathology
- Humans
- Induced Pluripotent Stem Cells/drug effects
- Induced Pluripotent Stem Cells/physiology
- Models, Cardiovascular
- Mutation, Missense
- Myocytes, Cardiac/drug effects
- Myocytes, Cardiac/physiology
- Rabbits
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Affiliation(s)
| | - Andrew G. Edwards
- Simula Research Laboratory, Oslo, Norway
- Department of Pharmacology, University of California, Davis, California United States of America
| | - Wayne R. Giles
- Simula Research Laboratory, Oslo, Norway
- Department of Physiology and Pharmacology, Faculty of Medicine, University of Calgary, Calgary, Canada
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14
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Ion current profiles in canine ventricular myocytes obtained by the "onion peeling" technique. J Mol Cell Cardiol 2021; 158:153-162. [PMID: 34089737 DOI: 10.1016/j.yjmcc.2021.05.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 05/05/2021] [Accepted: 05/21/2021] [Indexed: 02/07/2023]
Abstract
The profiles of ion currents during the cardiac action potential can be visualized by the action potential voltage clamp technique. To obtain multiple ion current data from the same cell, the "onion peeling" technique, based on sequential pharmacological dissection of ion currents, has to be applied. Combination of the two methods allows recording of several ion current profiles from the same myocyte under largely physiological conditions. Using this approach, we have studied the densities and integrals of the major cardiac inward (ICa, INCX, INa-late) and outward (IKr, IKs, IK1) currents in canine ventricular cells and studied the correlation between them. For this purpose, canine ventricular cardiomyocytes were chosen because their electrophysiological properties are similar to those of human ones. Significant positive correlation was observed between the density and integral of ICa and IKr, and positive correlation was found also between the integral of ICa and INCX. No further correlations were detected. The Ca2+-sensitivity of K+ currents was studied by comparing their parameters in the case of normal calcium homeostasis and following blockade of ICa. Out of the three K+ currents studied, only IKs was Ca2+-sensitive. The density and integral of IKs was significantly greater, while its time-to-peak value was shorter at normal Ca2+ cycling than following ICa blockade. No differences were detected for IKr or IK1 in this regard. Present results indicate that the positive correlation between ICa and IKr prominently contribute to the balance between inward and outward fluxes during the action potential plateau in canine myocytes. The results also suggest that the profiles of cardiac ion currents have to be studied under physiological conditions, since their behavior may strongly be influenced by the intracellular Ca2+ homeostasis and the applied membrane potential protocol.
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15
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Srinivasan NT, Garcia J, Schilling RJ, Ahsan S, Hunter RJ, Lowe M, Chow AW, Lambiase PD. Dynamic spatial dispersion of repolarization is present in regions critical for ischemic ventricular tachycardia ablation. Heart Rhythm O2 2021; 2:280-289. [PMID: 34337579 PMCID: PMC8322930 DOI: 10.1016/j.hroo.2021.05.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND The presence of dynamic substrate changes may facilitate functional block and reentry in ventricular tachycardia (VT). OBJECTIVE We aimed to study dynamic ventricular repolarization changes in critical regions of the VT circuit during sensed single extrastimulus pacing known as the Sense Protocol (SP). METHODS Twenty patients (aged 67 ± 9 years, 17 male) underwent VT ablation. A bipolar voltage map was obtained during sinus rhythm (SR) and right ventricular SP pacing at 20 ms above ventricular effective refractory period. Ventricular repolarization maps were constructed. Ventricular repolarization time (RT) was calculated from unipolar electrogram T waves, using the Wyatt method, as the dV/dtmax of the unipolar T wave. Entrainment or pace mapping confirmed critical sites for ablation. RESULTS The median global repolarization range (max-min RT per patient) was 166 ms (interquartile range [IQR] 143-181 ms) during SR mapping vs 208 ms (IQR 182-234) during SP mapping (P = .0003 vs intrinsic rhythm). Regions of late potentials (LP) had a longer RT during SP mapping compared to regions without LP (mean 394 ± 40 ms vs 342 ± 25 ms, P < .001). In paired regions of normal myocardium there was no significant spatial dispersion of repolarization (SDR)/10 mm2 during SP mapping vs SR mapping (SDR 11 ± 6 ms vs 10 ± 6 ms, P = .54). SDR/10 mm2 was greater in critical areas of the VT circuit during SP mapping 63 ± 29 ms vs SR mapping 16 ± 9 ms (P < .001). CONCLUSION Ventricular repolarization is prolonged in regions of LP and increases dynamically, resulting in dynamic SDR in critical areas of the VT circuit. These dynamic substrate changes may be an important factor that facilitates VT circuits.
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Affiliation(s)
- Neil T. Srinivasan
- Department of Cardiac Electrophysiology, The Essex Cardiothoracic Centre, Basildon, Essex, United Kingdom
- Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew’s Hospital, London, United Kingdom
- Institute of Cardiovascular Science, University College London, London, United Kingdom
- Circulatory Health Research Group, Medical Technology Research Centre, School of Medicine, Anglia Ruskin University, Essex, United Kingdom
| | - Jason Garcia
- Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew’s Hospital, London, United Kingdom
| | - Richard J. Schilling
- Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew’s Hospital, London, United Kingdom
| | - Syed Ahsan
- Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew’s Hospital, London, United Kingdom
| | - Ross J. Hunter
- Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew’s Hospital, London, United Kingdom
| | - Martin Lowe
- Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew’s Hospital, London, United Kingdom
| | - Anthony W. Chow
- Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew’s Hospital, London, United Kingdom
| | - Pier D. Lambiase
- Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew’s Hospital, London, United Kingdom
- Institute of Cardiovascular Science, University College London, London, United Kingdom
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16
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Liu P, Wang L, Han D, Sun C, Xue X, Li G. Acquired long QT syndrome in chronic kidney disease patients. Ren Fail 2020; 42:54-65. [PMID: 31878817 PMCID: PMC6968512 DOI: 10.1080/0886022x.2019.1707098] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2019] [Revised: 11/30/2019] [Accepted: 12/01/2019] [Indexed: 12/19/2022] Open
Abstract
Cardiovascular disease (CVD) is the leading cause of morbidity and mortality in chronic kidney disease (CKD) patients. QT interval prolongation is a congenital or acquired condition that is associated with an increased risk of torsade de pointes (TdP), sudden cardiac death (SCD), and all-cause mortality in the general population. The prevalence of acquired long QT syndrome (aLQTS) is high, and various acquired conditions contribute to the prolonged QT interval in patients with CKD. More notably, the prolonged QT interval in CKD is an independent risk factor for SCD and all-cause mortality. In this review, we focus on the epidemiological characteristics, risk factors, underlying mechanisms and treatments of aLQTS in CKD, promoting the management of aLQTS in CKD patients.
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Affiliation(s)
- Peng Liu
- Department of Cardiovascular Medicine, First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, P.R. China;
| | - Lu Wang
- Department of Cardiovascular Medicine, First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, P.R. China;
- Department of Endocrinology, First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, P.R. China
| | - Dan Han
- Department of Cardiovascular Medicine, First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, P.R. China;
| | - Chaofeng Sun
- Department of Cardiovascular Medicine, First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, P.R. China;
| | - Xiaolin Xue
- Department of Cardiovascular Medicine, First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, P.R. China;
| | - Guoliang Li
- Department of Cardiovascular Medicine, First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, P.R. China;
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Li G, Woltz RL, Wang CY, Ren L, He PX, Yu SD, Liu XQ, Yarov-Yarovoy V, Hu D, Chiamvimonvat N, Wu L. Gating Properties of Mutant Sodium Channels and Responses to Sodium Current Inhibitors Predict Mexiletine-Sensitive Mutations of Long QT Syndrome 3. Front Pharmacol 2020; 11:1182. [PMID: 32848785 PMCID: PMC7417866 DOI: 10.3389/fphar.2020.01182] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 07/20/2020] [Indexed: 12/11/2022] Open
Abstract
Background Long QT syndrome 3 (LQT3) is caused by SCN5A mutations. Late sodium current (late INa) inhibitors are current-specific to treat patients with LQT3, but the mechanisms underlying mexiletine (MEX) -sensitive (N1325S and R1623Q) and -insensitive (M1652R) mutations remains to be elucidated. Methods LQT3 patients with causative mutations were treated with oral MEX following i.v. lidocaine. Whole-cell patch-clamp techniques and molecular remodeling were used to determine the mechanisms underlying the sensitivity to MEX. Results Intravenous administration of lidocaine followed by MEX orally in LQT patients with N1325S and R1623Q sodium channel mutation shortened QTc interval, abolished arrhythmias, and completely normalized the ECG. In HEK293 cells, the steady-state inactivation curves of the M1652R channels were rightward shifted by 5.6 mV relative to the WT channel. In contrast, the R1623Q mutation caused a leftward shift of the steady-state inactivation curve by 15.2 mV compared with WT channel, and N1325S mutation did not affect steady-state inactivation (n = 5–13, P < 0.05). The extent of the window current was expanded in all three mutant channels compared with WT. All three mutations increased late INa with the greatest amplitude in the M1652R channel (n = 9–15, P < 0.05). MEX caused a hyperpolarizing shift of the steady-state inactivation and delayed the recovery of all three mutant channels. Furthermore, it suppressed late INa in N1325S and R1623Q to a greater extent compared to that of M1652R mutant channel. Mutations altered the sensitivity of Nav1.5 to MEX through allosteric mechanisms by changing the conformation of Nav1.5 to become more or less favorable for MEX binding. Late INa inhibitors suppressed late INa in N1325S and R1623Q to a greater extent than that in the M1652R mutation (n = 4–7, P < 0.05). Conclusion The N1325S, R1623Q, and M1652R mutations are associated with a variable augmentation of late INa, which was reversed by MEX. M1652R mutation changes the conformation of Nav1.5 that disrupt the inactivation of channel affecting MEX binding, corresponding to the poor response to MEX. The lidocaine test, molecular modeling, and drugs screening in cells expressing mutant channels are useful for predicting the effectiveness of late INa inhibitors.
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Affiliation(s)
- Gang Li
- Department of Cardiology, Peking University First Hospital, Beijing, China
| | - Ryan L Woltz
- Division of Cardiovascular Medicine, Department of Internal Medicine, School of Medicine, University of California, Davis, Davis, CA, United States
| | - Cheng-Yu Wang
- Department of Cardiology, Peking University First Hospital, Beijing, China
| | - Lu Ren
- Division of Cardiovascular Medicine, Department of Internal Medicine, School of Medicine, University of California, Davis, Davis, CA, United States
| | - Pei-Xin He
- Department of Cardiology, Peking University First Hospital, Beijing, China
| | - Shan-Dong Yu
- Department of Cardiology, Peking University First Hospital, Beijing, China
| | - Xue-Qin Liu
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Vladimir Yarov-Yarovoy
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, Davis, CA, United States
| | - Dan Hu
- Department of Cardiology and Cardiovascular Research Institute, Renmin Hospital of Wuhan University and Hubei Key Laboratory of Cardiology, Wuhan, China
| | - Nipavan Chiamvimonvat
- Division of Cardiovascular Medicine, Department of Internal Medicine, School of Medicine, University of California, Davis, Davis, CA, United States.,Department of Veterans Affairs, Northern California Health Care System, Mather, CA, United States
| | - Lin Wu
- Department of Cardiology, Peking University First Hospital, Beijing, China.,Key Laboratory of Medical Electrophysiology, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China
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18
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Hwang J, Kim TY, Terentyev D, Zhong M, Kabakov AY, Bronk P, Arunachalam K, Belardinelli L, Rajamani S, Kunitomo Y, Pfeiffer Z, Lu Y, Peng X, Odening KE, Qu Z, Karma A, Koren G, Choi BR. Late I Na Blocker GS967 Supresses Polymorphic Ventricular Tachycardia in a Transgenic Rabbit Model of Long QT Type 2. Circ Arrhythm Electrophysiol 2020; 13:e006875. [PMID: 32628505 PMCID: PMC10626560 DOI: 10.1161/circep.118.006875] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
BACKGROUND Long QT syndrome has been associated with sudden cardiac death likely caused by early afterdepolarizations (EADs) and polymorphic ventricular tachycardias (PVTs). Suppressing the late sodium current (INaL) may counterbalance the reduced repolarization reserve in long QT syndrome and prevent EADs and PVTs. METHODS We tested the effects of the selective INaL blocker GS967 on PVT induction in a transgenic rabbit model of long QT syndrome type 2 using intact heart optical mapping, cellular electrophysiology and confocal Ca2+ imaging, and computer modeling. RESULTS GS967 reduced ventricular fibrillation induction under a rapid pacing protocol (n=7/14 hearts in control versus 1/14 hearts at 100 nmol/L) without altering action potential duration or restitution and dispersion. GS967 suppressed PVT incidences by reducing Ca2+-mediated EADs and focal activity during isoproterenol perfusion (at 30 nmol/L, n=7/12 and 100 nmol/L n=8/12 hearts without EADs and PVTs). Confocal Ca2+ imaging of long QT syndrome type 2 myocytes revealed that GS967 shortened Ca2+ transient duration via accelerating Na+/Ca2+ exchanger (INCX)-mediated Ca2+ efflux from cytosol, thereby reducing EADs. Computer modeling revealed that INaL potentiates EADs in the long QT syndrome type 2 setting through (1) providing additional depolarizing currents during action potential plateau phase, (2) increasing intracellular Na+ (Nai) that decreases the depolarizing INCX thereby suppressing the action potential plateau and delaying the activation of slowly activating delayed rectifier K+ channels (IKs), suggesting important roles of INaL in regulating Nai. CONCLUSIONS Selective INaL blockade by GS967 prevents EADs and abolishes PVT in long QT syndrome type 2 rabbits by counterbalancing the reduced repolarization reserve and normalizing Nai. Graphic Abstract: A graphic abstract is available for this article.
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Affiliation(s)
- Jungmin Hwang
- Cardiovascular Rsrch Ctr, Division of Cardiology, Rhode Island Hospital, Alpert Medical School of Brown Univ, Providence
- College of Pharmacy, Univ of Rhode Island, Kingstown, RI
| | - Tae Yun Kim
- Cardiovascular Rsrch Ctr, Division of Cardiology, Rhode Island Hospital, Alpert Medical School of Brown Univ, Providence
| | - Dmitry Terentyev
- Cardiovascular Rsrch Ctr, Division of Cardiology, Rhode Island Hospital, Alpert Medical School of Brown Univ, Providence
| | | | - Anatoli Y. Kabakov
- Cardiovascular Rsrch Ctr, Division of Cardiology, Rhode Island Hospital, Alpert Medical School of Brown Univ, Providence
| | - Peter Bronk
- Cardiovascular Rsrch Ctr, Division of Cardiology, Rhode Island Hospital, Alpert Medical School of Brown Univ, Providence
| | - Karuppiah Arunachalam
- Cardiovascular Rsrch Ctr, Division of Cardiology, Rhode Island Hospital, Alpert Medical School of Brown Univ, Providence
| | | | - Sridharan Rajamani
- Former employee: Dept of Biology, Gilead Science, Foster City, CA
- Amgen Inc, South San Francisco, CA
| | - Yukiko Kunitomo
- Cardiovascular Rsrch Ctr, Division of Cardiology, Rhode Island Hospital, Alpert Medical School of Brown Univ, Providence
| | - Zachary Pfeiffer
- Cardiovascular Rsrch Ctr, Division of Cardiology, Rhode Island Hospital, Alpert Medical School of Brown Univ, Providence
| | - Yichun Lu
- Cardiovascular Rsrch Ctr, Division of Cardiology, Rhode Island Hospital, Alpert Medical School of Brown Univ, Providence
| | - Xuwen Peng
- Dept of Comparative Medicine, Pennsylvania State Univ College of Medicine, Hershey, PA
| | - Katja E. Odening
- Dept of Cardiology & Angiology I, Heart Ctr, Univ of Freiburg, Germany
| | - Zhilin Qu
- Dept of Medicine, Univ of California, Los Angeles
| | - Alain Karma
- Dept of Physics, Northeastern Univ, Boston, MA
| | - Gideon Koren
- Cardiovascular Rsrch Ctr, Division of Cardiology, Rhode Island Hospital, Alpert Medical School of Brown Univ, Providence
| | - Bum-Rak Choi
- Cardiovascular Rsrch Ctr, Division of Cardiology, Rhode Island Hospital, Alpert Medical School of Brown Univ, Providence
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19
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Men J, Li A, Jerwick J, Li Z, Tanzi RE, Zhou C. Non-invasive red-light optogenetic control of Drosophila cardiac function. Commun Biol 2020; 3:336. [PMID: 32601302 PMCID: PMC7324573 DOI: 10.1038/s42003-020-1065-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Accepted: 06/03/2020] [Indexed: 02/03/2023] Open
Abstract
Drosophila is a powerful genetic model system for cardiovascular studies. Recently, optogenetic pacing tools have been developed to control Drosophila heart rhythm noninvasively with blue light, which has a limited penetration depth. Here we developed both a red-light sensitive opsin expressing Drosophila system and an integrated red-light stimulation and optical coherence microscopy (OCM) imaging system. We demonstrated noninvasive control of Drosophila cardiac rhythms using a single light source, including simulated tachycardia in ReaChR-expressing flies and bradycardia and cardiac arrest in halorhodopsin (NpHR)-expressing flies at multiple developmental stages. By using red excitation light, we were able to pace flies at higher efficiency and with lower power than with equivalent blue light excitation systems. The recovery dynamics after red-light stimulation of NpHR flies were observed and quantified. The combination of red-light stimulation, OCM imaging, and transgenic Drosophila systems provides a promising and easily manipulated research platform for noninvasive cardiac optogenetic studies. Men et al. develop an optogenetic pacing tool to control Drosophila heart rhythm noninvasively with red light. Using optical coherence microscopy imaging, they demonstrate effective light-induced tachypacing, bradypacing, and restorable cardiac arrest in transgenic fly models. This study provides a user-friendly research platform for noninvasive cardiac optogenetic studies.
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Affiliation(s)
- Jing Men
- Department of Bioengineering, Lehigh University, Bethlehem, PA, 18015, USA.,Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, 63105, USA
| | - Airong Li
- Genetics and Aging Research Unit, McCance Center for Brain Health, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, 02114, USA
| | - Jason Jerwick
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, 63105, USA.,Department of Electrical and Computer Engineering, Lehigh University, Bethlehem, PA, 18015, USA
| | - Zilong Li
- Genetics and Aging Research Unit, McCance Center for Brain Health, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, 02114, USA
| | - Rudolph E Tanzi
- Genetics and Aging Research Unit, McCance Center for Brain Health, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, 02114, USA
| | - Chao Zhou
- Department of Bioengineering, Lehigh University, Bethlehem, PA, 18015, USA. .,Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, 63105, USA. .,Department of Electrical and Computer Engineering, Lehigh University, Bethlehem, PA, 18015, USA.
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20
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Horváth B, Hézső T, Kiss D, Kistamás K, Magyar J, Nánási PP, Bányász T. Late Sodium Current Inhibitors as Potential Antiarrhythmic Agents. Front Pharmacol 2020; 11:413. [PMID: 32372952 PMCID: PMC7184885 DOI: 10.3389/fphar.2020.00413] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Accepted: 03/18/2020] [Indexed: 12/19/2022] Open
Abstract
Based on recent findings, an increased late sodium current (INa,late) plays an important pathophysiological role in cardiac diseases, including rhythm disorders. The article first describes what is INa,late and how it functions under physiological circumstances. Next, it shows the wide range of cellular mechanisms that can contribute to an increased INa,late in heart diseases, and also discusses how the upregulated INa,late can play a role in the generation of cardiac arrhythmias. The last part of the article is about INa,late inhibiting drugs as potential antiarrhythmic agents, based on experimental and preclinical data as well as in the light of clinical trials.
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Affiliation(s)
- Balázs Horváth
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- Faculty of Pharmacy, University of Debrecen, Debrecen, Hungary
| | - Tamás Hézső
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Dénes Kiss
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Kornél Kistamás
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - János Magyar
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- Division of Sport Physiology, University of Debrecen, Debrecen, Hungary
| | - Péter P. Nánási
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- Department of Dental Physiology and Pharmacology, Faculty of Dentistry, University of Debrecen, Debrecen, Hungary
| | - Tamás Bányász
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
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21
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Hegyi B, Chen-Izu Y, Izu LT, Rajamani S, Belardinelli L, Bers DM, Bányász T. Balance Between Rapid Delayed Rectifier K + Current and Late Na + Current on Ventricular Repolarization: An Effective Antiarrhythmic Target? Circ Arrhythm Electrophysiol 2020; 13:e008130. [PMID: 32202931 PMCID: PMC7331791 DOI: 10.1161/circep.119.008130] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND Rapid delayed rectifier K+ current (IKr) and late Na+ current (INaL) significantly shape the cardiac action potential (AP). Changes in their magnitudes can cause either long or short QT syndromes associated with malignant ventricular arrhythmias and sudden cardiac death. METHODS Physiological self AP-clamp was used to measure INaL and IKr during the AP in rabbit and porcine ventricular cardiomyocytes to test our hypothesis that the balance between IKr and INaL affects repolarization stability in health and disease conditions. RESULTS We found comparable amount of net charge carried by IKr and INaL during the physiological AP, suggesting that outward K+ current via IKr and inward Na+ current via INaL are in balance during physiological repolarization. Remarkably, IKr and INaL integrals in each control myocyte were highly correlated in both healthy rabbit and pig myocytes, despite high overall cell-to-cell variability. This close correlation was lost in heart failure myocytes from both species. Pretreatment with E-4031 to block IKr (mimicking long QT syndrome 2) or with sea anemone toxin II to impair Na+ channel inactivation (mimicking long QT syndrome 3) prolonged AP duration (APD); however, using GS-967 to inhibit INaL sufficiently restored APD to control in both cases. Importantly, INaL inhibition significantly reduced the beat-to-beat and short-term variabilities of APD. Moreover, INaL inhibition also restored APD and repolarization stability in heart failure. Conversely, pretreatment with GS-967 shortened APD (mimicking short QT syndrome), and E-4031 reverted APD shortening. Furthermore, the amplitude of AP alternans occurring at high pacing frequency was decreased by INaL inhibition, increased by IKr inhibition, and restored by combined INaL and IKr inhibitions. CONCLUSIONS Our data demonstrate that IKr and INaL are counterbalancing currents during the physiological ventricular AP and their integrals covary in individual myocytes. Targeting these ionic currents to normalize their balance may have significant therapeutic potential in heart diseases with repolarization abnormalities. Visual Overview: A visual overview is available for this article.
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Affiliation(s)
- Bence Hegyi
- Department of Pharmacology, University of California, Davis
| | - Ye Chen-Izu
- Department of Pharmacology, University of California, Davis
- Department of Biomedical Engineering, University of California, Davis
- Department of Internal Medicine/Cardiology, University of California, Davis
| | | | - Sridharan Rajamani
- Amgen, Inc., South San Francisco, University of Debrecen, Debrecen, Hungary
| | - Luiz Belardinelli
- InCarda Therapeutics, Inc., Newark, CA, University of Debrecen, Debrecen, Hungary
| | - Donald M. Bers
- Department of Pharmacology, University of California, Davis
| | - Tamás Bányász
- Department of Pharmacology, University of California, Davis
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
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22
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Gade AR, Marx SO, Pitt GS. An interaction between the III-IV linker and CTD in NaV1.5 confers regulation of inactivation by CaM and FHF. J Gen Physiol 2020; 152:e201912434. [PMID: 31865383 PMCID: PMC7062510 DOI: 10.1085/jgp.201912434] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Accepted: 11/25/2019] [Indexed: 12/19/2022] Open
Abstract
Voltage gated sodium channel (VGSC) activation drives the action potential upstroke in cardiac myocytes, skeletal muscles, and neurons. After opening, VGSCs rapidly enter a non-conducting, inactivated state. Impaired inactivation causes persistent inward current and underlies cardiac arrhythmias. VGSC auxiliary proteins calmodulin (CaM) and fibroblast growth factor homologous factors (FHFs) bind to the channel's C-terminal domain (CTD) and limit pathogenic persistent currents. The structural details and mechanisms mediating these effects are not clear. Building on recently published cryo-EM structures, we show that CaM and FHF limit persistent currents in the cardiac NaV1.5 VGSC by stabilizing an interaction between the channel's CTD and III-IV linker region. Perturbation of this intramolecular interaction increases persistent current and shifts the voltage dependence of steady-state inactivation. Interestingly, the NaV1.5 residues involved in the interaction are sites mutated in the arrhythmogenic long QT3 syndrome (LQT3). Along with electrophysiological investigations of this interaction, we present structural models that suggest how CaM and FHF stabilize the interaction and thereby limit the persistent current. The critical residues at the interaction site are conserved among VGSC isoforms, and subtle substitutions provide an explanation for differences in inactivation among the isoforms.
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Affiliation(s)
- Aravind R. Gade
- Cardiovascular Research Institute, Weill Cornell Medicine, New York, NY
| | - Steven O. Marx
- Division of Cardiology, Department of Medicine, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY
- Department of Pharmacology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY
| | - Geoffrey S. Pitt
- Cardiovascular Research Institute, Weill Cornell Medicine, New York, NY
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23
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Del Canto I, Santamaría L, Genovés P, Such-Miquel L, Arias-Mutis O, Zarzoso M, Soler C, Parra G, Tormos Á, Alberola A, Such L, Chorro FJ. Effects of the Inhibition of Late Sodium Current by GS967 on Stretch-Induced Changes in Cardiac Electrophysiology. Cardiovasc Drugs Ther 2019; 32:413-425. [PMID: 30173392 DOI: 10.1007/s10557-018-6822-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
PURPOSE Mechanical stretch increases sodium and calcium entry into myocytes and activates the late sodium current. GS967, a triazolopyridine derivative, is a sodium channel blocker with preferential effects on the late sodium current. The present study evaluates whether GS967 inhibits or modulates the arrhythmogenic electrophysiological effects of myocardial stretch. METHODS Atrial and ventricular refractoriness and ventricular fibrillation modifications induced by acute stretch were studied in Langendorff-perfused rabbit hearts (n = 28) using epicardial multiple electrodes and high-resolution mapping techniques under control conditions and during the perfusion of GS967 at different concentrations (0.03, 0.1, and 0.3 μM). RESULTS On comparing ventricular refractoriness, conduction velocity and wavelength obtained before stretch had no significant changes under each GS967 concentration while atrial refractoriness increased under GS967 0.3 μM. Under GS967, the stretch-induced changes were attenuated, and no significant differences were observed between before and during stretch. GS967 0.3 μM diminished the normal stretch-induced changes resulting in longer (less shortened) atrial refractoriness (138 ± 26 ms vs 95 ± 9 ms; p < 0.01), ventricular refractoriness (155 ± 18 ms vs 124 ± 16 ms; p < 0.01) and increments in spectral concentration (23 ± 5% vs 17 ± 2%; p < 0.01), the fifth percentile of ventricular activation intervals (46 ± 8 ms vs 31 ± 3 ms; p < 0.05), and wavelength of ventricular fibrillation (2.5 ±0.5 cm vs 1.7 ± 0.3 cm; p < 0.05) during stretch. The stretch-induced increments in dominant frequency during ventricular fibrillation (control = 38%, 0.03 μM = 33%, 0.1 μM = 33%, 0.3 μM = 14%; p < 0.01) and the stretch-induced increments in arrhythmia complexity index (control = 62%, 0.03μM = 41%, 0.1 μM = 32%, 0.3 μM = 16%; p < 0.05) progressively decreased on increasing the GS967 concentration. CONCLUSIONS GS967 attenuates stretch-induced changes in cardiac electrophysiology.
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Affiliation(s)
- Irene Del Canto
- CIBER CV. Carlos III Health Institute, Madrid, Spain.,Department of Electronics, Universitat Politècnica de València, Valencia, Spain
| | - Laura Santamaría
- Department of Physiology, Valencia University - Estudi General, Valencia, Spain
| | | | - Luis Such-Miquel
- CIBER CV. Carlos III Health Institute, Madrid, Spain.,Department of Physiotherapy, Valencia University - Estudi General, Valencia, Spain
| | | | - Manuel Zarzoso
- Department of Physiotherapy, Valencia University - Estudi General, Valencia, Spain
| | - Carlos Soler
- Department of Physiology, Valencia University - Estudi General, Valencia, Spain
| | - Germán Parra
- Department of Physiology, Valencia University - Estudi General, Valencia, Spain
| | - Álvaro Tormos
- CIBER CV. Carlos III Health Institute, Madrid, Spain.,Department of Electronics, Universitat Politècnica de València, Valencia, Spain
| | - Antonio Alberola
- CIBER CV. Carlos III Health Institute, Madrid, Spain.,Department of Physiology, Valencia University - Estudi General, Valencia, Spain
| | - Luis Such
- CIBER CV. Carlos III Health Institute, Madrid, Spain.,Department of Physiology, Valencia University - Estudi General, Valencia, Spain
| | - Francisco J Chorro
- CIBER CV. Carlos III Health Institute, Madrid, Spain. .,Service of Cardiology, Valencia University Clinic Hospital, INCLIVA, Valencia, Spain. .,Department of Medicine, Valencia University - Estudi General, Valencia, Spain. .,Servicio de Cardiología, Hospital Clínico Universitario, Avda. Blasco Ibañez 17, 46010, Valencia, Spain.
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24
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Hegyi B, Morotti S, Liu C, Ginsburg KS, Bossuyt J, Belardinelli L, Izu LT, Chen-Izu Y, Bányász T, Grandi E, Bers DM. Enhanced Depolarization Drive in Failing Rabbit Ventricular Myocytes: Calcium-Dependent and β-Adrenergic Effects on Late Sodium, L-Type Calcium, and Sodium-Calcium Exchange Currents. Circ Arrhythm Electrophysiol 2019; 12:e007061. [PMID: 30879336 PMCID: PMC6720130 DOI: 10.1161/circep.118.007061] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND Heart failure (HF) is characterized by electrophysiological remodeling resulting in increased risk of cardiac arrhythmias. Previous reports suggest that elevated inward ionic currents in HF promote action potential (AP) prolongation, increased short-term variability of AP repolarization, and delayed afterdepolarizations. However, the underlying changes in late Na+ current (INaL), L-type Ca2+ current, and NCX (Na+/Ca2+ exchanger) current are often measured in nonphysiological conditions (square-pulse voltage clamp, slow pacing rates, exogenous Ca2+ buffers). METHODS We measured the major inward currents and their Ca2+- and β-adrenergic dependence under physiological AP clamp in rabbit ventricular myocytes in chronic pressure/volume overload-induced HF (versus age-matched control). RESULTS AP duration and short-term variability of AP repolarization were increased in HF, and importantly, inhibition of INaL decreased both parameters to the control level. INaL was slightly increased in HF versus control even when intracellular Ca2+ was strongly buffered. But under physiological AP clamp with normal Ca2+ cycling, INaL was markedly upregulated in HF versus control (dependent largely on CaMKII [Ca2+/calmodulin-dependent protein kinase II] activity). β-Adrenergic stimulation (often elevated in HF) further enhanced INaL. L-type Ca2+ current was decreased in HF when Ca2+ was buffered, but CaMKII-mediated Ca2+-dependent facilitation upregulated physiological L-type Ca2+ current to the control level. Furthermore, L-type Ca2+ current response to β-adrenergic stimulation was significantly attenuated in HF. Inward NCX current was upregulated at phase 3 of AP in HF when assessed by combining experimental data and computational modeling. CONCLUSIONS Our results suggest that CaMKII-dependent upregulation of INaL in HF significantly contributes to AP prolongation and increased short-term variability of AP repolarization, which may lead to increased arrhythmia propensity, and is further exacerbated by adrenergic stress.
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Affiliation(s)
- Bence Hegyi
- Department of Pharmacology, University of California Davis, Davis
| | - Stefano Morotti
- Department of Pharmacology, University of California Davis, Davis
| | - Caroline Liu
- Department of Pharmacology, University of California Davis, Davis
| | | | - Julie Bossuyt
- Department of Pharmacology, University of California Davis, Davis
| | | | - Leighton T. Izu
- Department of Pharmacology, University of California Davis, Davis
| | - Ye Chen-Izu
- Department of Pharmacology, University of California Davis, Davis
- Department of Biomedical Engineering, University of California Davis, Davis
- Department of Internal Medicine/Cardiology, University of California Davis, Davis
| | - Tamás Bányász
- Department of Pharmacology, University of California Davis, Davis
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Eleonora Grandi
- Department of Pharmacology, University of California Davis, Davis
| | - Donald M. Bers
- Department of Pharmacology, University of California Davis, Davis
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25
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Burashnikov A, Antzelevitch C. Effectiveness of Late INa Versus Peak INa Block in the Setting of Ventricular Fibrillation. Circ Arrhythm Electrophysiol 2019; 10:CIRCEP.117.005111. [PMID: 28314847 DOI: 10.1161/circep.117.005111] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Alexander Burashnikov
- From the Lankenau Institute for Medical Research (A.B., C.A.), Lankenau Heart Institute (C.A.), Wynnewood, PA; and Sidney Kimmel Medical College of Thomas Jefferson University, Philadelphia, PA (A.B.)
| | - Charles Antzelevitch
- From the Lankenau Institute for Medical Research (A.B., C.A.), Lankenau Heart Institute (C.A.), Wynnewood, PA; and Sidney Kimmel Medical College of Thomas Jefferson University, Philadelphia, PA (A.B.).
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26
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Increase in CO 2 levels by upregulating late sodium current is proarrhythmic in the heart. Heart Rhythm 2019; 16:1098-1106. [PMID: 30710739 DOI: 10.1016/j.hrthm.2019.01.029] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Indexed: 12/19/2022]
Abstract
BACKGROUND Increased CO2 levels in the general circulation and/or in the myocardium are common under pathologic conditions. OBJECTIVE The purpose of this study was to test the hypothesis that an increase in CO2 levels, and not just the subsequent extra- or intracellular acidosis, would augment late sodium current (INa,L) and contribute to arrhythmogenesis in hearts with reduced repolarization reserve. METHODS Monophasic action potential durations at 90% completion of repolarization (MAPD90) from isolated rabbit hearts, INa,L, and extra- (pHo) and intracellular pH (pHi) values from cardiomyocytes using the whole-cell patch-clamp techniques and 2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein, acetoxymethyl ester (BCECF-AM), respectively, were measured. RESULTS Increasing CO2 levels from 5% to 10% and 20% and administration of 1 nM sea anemone toxin (ATX)-II increased INa,L and prolonged both epicardial and endocardial MAPD90 (n = 7 and 10, respectively) without causing arrhythmic activities. Compared to 5% CO2, 10% and 20% CO2 decreased pHo and pHi in hearts treated with 1 nM ATX-II, caused greater prolongation of MAPD90, and elicited ventricular tachycardias. Increasing CO2 levels from 5% to 10% and 20% with pHo maintained at 7.4 produced smaller changes in pHi (P <.05) but similar increases in INa,L, prolongation of MAPD90, and incidence of ventricular tachycardias (n = 8). Inhibition of INa,L reversed the increase in INa,L, suppressed MAPD90 prolongations, and ventricular tachycardias induced by 20% CO2. Increased phospho-calmodulin-dependent protein kinase II-δ (CaMKIIδ) and phospho-NaV1.5 protein levels in hearts treated with 20% CO2 was attenuated by eleclazine. CONCLUSION Increased CO2 levels enhance INa,L and are proarrhythmic factors in hearts with reduced repolarization reserve, possibly via mechanisms related to phosphorylation of CaMKIIδ and NaV1.5.
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Li G, Zhang L. The role of mexiletine in the management of long QT syndrome. J Electrocardiol 2018; 51:1061-1065. [DOI: 10.1016/j.jelectrocard.2018.08.035] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 08/27/2018] [Accepted: 08/30/2018] [Indexed: 01/25/2023]
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Ferrantini C, Pioner JM, Mazzoni L, Gentile F, Tosi B, Rossi A, Belardinelli L, Tesi C, Palandri C, Matucci R, Cerbai E, Olivotto I, Poggesi C, Mugelli A, Coppini R. Late sodium current inhibitors to treat exercise-induced obstruction in hypertrophic cardiomyopathy: an in vitro study in human myocardium. Br J Pharmacol 2018; 175:2635-2652. [PMID: 29579779 PMCID: PMC6003658 DOI: 10.1111/bph.14223] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Revised: 03/07/2018] [Accepted: 03/08/2018] [Indexed: 12/19/2022] Open
Abstract
Background and Purpose In 30–40% of hypertrophic cardiomyopathy (HCM) patients, symptomatic left ventricular (LV) outflow gradients develop only during exercise due to catecholamine‐induced LV hypercontractility (inducible obstruction). Negative inotropic pharmacological options are limited to β‐blockers or disopyramide, with low efficacy and tolerability. We assessed the potential of late sodium current (INaL)‐inhibitors to treat inducible obstruction in HCM. Experimental Approach The electrophysiological and mechanical responses to β‐adrenoceptor stimulation were studied in human myocardium from HCM and control patients. Effects of INaL‐inhibitors (ranolazine and GS‐967) in HCM samples were investigated under conditions simulating rest and exercise. Key Results In cardiomyocytes and trabeculae from 18 surgical septal samples of patients with obstruction, the selective INaL‐inhibitor GS‐967 (0.5 μM) hastened twitch kinetics, decreased diastolic [Ca2+] and shortened action potentials, matching the effects of ranolazine (10μM). Mechanical responses to isoprenaline (inotropic and lusitropic) were comparable in HCM and control myocardium. However, isoprenaline prolonged action potentials in HCM myocardium, while it shortened them in controls. Unlike disopyramide, neither GS‐967 nor ranolazine reduced force at rest. However, in the presence of isoprenaline, they reduced Ca2+‐transient amplitude and twitch tension, while the acceleration of relaxation was maintained. INaL‐inhibitors were more effective than disopyramide in reducing contractility during exercise. Finally, INaL‐inhibitors abolished arrhythmias induced by isoprenaline. Conclusions and Implications Ranolazine and GS‐967 reduced septal myocardium tension during simulated exercise in vitro and therefore have the potential to ameliorate symptoms caused by inducible obstruction in HCM patients, with some advantages over disopyramide and β‐blockers.
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Affiliation(s)
- Cecilia Ferrantini
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy.,Cardiomyopathy Unit, Careggi University Hospital, Florence, Italy
| | - Josè Manuel Pioner
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
| | - Luca Mazzoni
- Department NeuroFarBa, University of Florence, Florence, Italy
| | - Francesca Gentile
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
| | - Benedetta Tosi
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
| | - Alessandra Rossi
- Cardiomyopathy Unit, Careggi University Hospital, Florence, Italy
| | | | - Chiara Tesi
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
| | - Chiara Palandri
- Department NeuroFarBa, University of Florence, Florence, Italy
| | - Rosanna Matucci
- Department NeuroFarBa, University of Florence, Florence, Italy
| | | | - Iacopo Olivotto
- Cardiomyopathy Unit, Careggi University Hospital, Florence, Italy
| | - Corrado Poggesi
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
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Yang T, Meoli DF, Moslehi J, Roden DM. Inhibition of the α-Subunit of Phosphoinositide 3-Kinase in Heart Increases Late Sodium Current and Is Arrhythmogenic. J Pharmacol Exp Ther 2018; 365:460-466. [PMID: 29563327 DOI: 10.1124/jpet.117.246157] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 02/28/2018] [Indexed: 02/06/2023] Open
Abstract
Although inhibition of phosphoinositide 3-kinase (PI3K) is an emerging strategy in cancer therapy, we and others have reported that this action can also contribute to drug-induced QT prolongation and arrhythmias by increasing cardiac late sodium current (INaL). Previous studies in mice implicate the PI3K-α isoform in arrhythmia susceptibility. Here, we have determined the effects of new anticancer drugs targeting specific PI3K isoforms on INaL and action potentials (APs) in mouse cardiomyocytes and Chinese hamster ovary cells (CHO). Chronic exposure (10-100 nM; 5-48 hours) to PI3K-α-specific subunit inhibitors BYL710 (alpelisib) and A66 and a pan-PI3K inhibitor (BKM120) increased INaL in SCN5A-transfected CHO cells and mouse cardiomyocytes. The specific inhibitors (10-100 nM for 5 hours) markedly prolonged APs and generated triggered activity in mouse cardiomyocytes (9/12) but not in controls (0/6), and BKM120 caused similar effects (3/6). The inclusion of water-soluble PIP3, a downstream effector of the PI3K signaling pathway, in the pipette solution reversed these arrhythmogenic effects. By contrast, inhibition of PI3K-β, -γ, and -δ isoforms did not alter INaL or APs. We conclude that inhibition of cardiac PI3K-α is arrhythmogenic by increasing INaL and this effect is not seen with inhibition of other PI3K isoforms. These results highlight a mechanism underlying potential cardiotoxicity of PI3K-α inhibitors.
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Affiliation(s)
- Tao Yang
- Departments of Medicine (T.Y., D.F.M, J.M., D.M.R.), Pharmacology (T.Y., D.M.R.), and Biomedical Informatics (D.M.R.), Vanderbilt University School of Medicine, Nashville, Tennessee
| | - David F Meoli
- Departments of Medicine (T.Y., D.F.M, J.M., D.M.R.), Pharmacology (T.Y., D.M.R.), and Biomedical Informatics (D.M.R.), Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Javid Moslehi
- Departments of Medicine (T.Y., D.F.M, J.M., D.M.R.), Pharmacology (T.Y., D.M.R.), and Biomedical Informatics (D.M.R.), Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Dan M Roden
- Departments of Medicine (T.Y., D.F.M, J.M., D.M.R.), Pharmacology (T.Y., D.M.R.), and Biomedical Informatics (D.M.R.), Vanderbilt University School of Medicine, Nashville, Tennessee
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Shattock MJ, Park KC, Yang HY, Lee AWC, Niederer S, MacLeod KT, Winter J. Restitution slope is principally determined by steady-state action potential duration. Cardiovasc Res 2018; 113:817-828. [PMID: 28371805 PMCID: PMC5437364 DOI: 10.1093/cvr/cvx063] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Accepted: 03/22/2017] [Indexed: 12/02/2022] Open
Abstract
Aims The steepness of the action potential duration (APD) restitution curve and local tissue refractoriness are both thought to play important roles in arrhythmogenesis. Despite this, there has been little recognition of the apparent association between steady-state APD and the slope of the restitution curve. The objective of this study was to test the hypothesis that restitution slope is determined by APD and to examine the relationship between restitution slope, refractoriness and susceptibility to VF. Methods and results Experiments were conducted in isolated hearts and ventricular myocytes from adult guinea pigs and rabbits. Restitution curves were measured under control conditions and following intervention to prolong (clofilium, veratridine, bretylium, low [Ca]e, chronic transverse aortic constriction) or shorten (catecholamines, rapid pacing) ventricular APD. Despite markedly differing mechanisms of action, all interventions that prolonged the action potential led to a steepening of the restitution curve (and vice versa). Normalizing the restitution curve as a % of steady-state APD abolished the difference in restitution curves with all interventions. Effects on restitution were preserved when APD was modulated by current injection in myocytes pre-treated with the calcium chelator BAPTA-AM – to abolish the intracellular calcium transient. The non-linear relation between APD and the rate of repolarization of the action potential is shown to underpin the common influence of APD on the slope of the restitution curve. Susceptibility to VF was found to parallel changes in APD/refractoriness, rather than restitution slope. Conclusion(s) Steady-state APD is the principal determinant of the slope of the ventricular electrical restitution curve. In the absence of post-repolarization refractoriness, factors that prolong the action potential would be expected to steepen the restitution curve. However, concomitant changes in tissue refractoriness act to reduce susceptibility to sustained VF. Dependence on steady-state APD may contribute to the failure of restitution slope to predict sudden cardiac death.
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Affiliation(s)
- Michael J Shattock
- Cardiovascular Division, King's College London, St Thomas' Hospital, Westminster Bridge Road, London SE1 7EH, UK
| | - Kyung Chan Park
- Cardiovascular Division, King's College London, St Thomas' Hospital, Westminster Bridge Road, London SE1 7EH, UK
| | - Hsiang-Yu Yang
- NHLI, ICTEM Building, Hammersmith Campus, Du Cane Road, London W12 0NN, UK.,Department of Surgery, Division of Cardiovascular Surgery, Tri-Service General Hospital, National Defense Medical Center, Taipei 114, Taiwan
| | - Angela W C Lee
- Biomedical Engineering, King's College London, St Thomas' Hospital, Westminster Bridge Road, London SE1 7EH, UK
| | - Steven Niederer
- Biomedical Engineering, King's College London, St Thomas' Hospital, Westminster Bridge Road, London SE1 7EH, UK
| | - Kenneth T MacLeod
- NHLI, ICTEM Building, Hammersmith Campus, Du Cane Road, London W12 0NN, UK
| | - James Winter
- Cardiovascular Division, King's College London, St Thomas' Hospital, Westminster Bridge Road, London SE1 7EH, UK
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El-Bizri N, Li CH, Liu GX, Rajamani S, Belardinelli L. Selective inhibition of physiological late Na+ current stabilizes ventricular repolarization. Am J Physiol Heart Circ Physiol 2018; 314:H236-H245. [DOI: 10.1152/ajpheart.00071.2017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The physiological role of cardiac late Na+ current ( INa) has not been well described. In this study, we tested the hypothesis that selective inhibition of physiological late INa abbreviates the normal action potential (AP) duration (APD) and counteracts the prolongation of APD and arrhythmic activities caused by inhibition of the delayed rectifier K+ current ( IKr). The effects of GS-458967 (GS967) on the physiological late INa and APs in rabbit isolated ventricular myocytes and on the monophasic APs and arrhythmias in rabbit isolated perfused hearts were determined. In ventricular myocytes, GS967 and, for comparison, tetrodotoxin concentration dependently decreased the physiological late INa with IC50 values of 0.5 and 1.9 µM, respectively, and significantly shortened the APD measured at 90% repolarization (APD90). A strong correlation between inhibition of the physiological late INa and shortening of APD by GS967 or tetrodotoxin ( R2 of 0.96 and 0.97, respectively) was observed. Pretreatment of isolated myocytes or hearts with GS967 (1 µM) significantly shortened APD90 and monophasic APD90 and prevented the prolongation and associated arrhythmias caused by the IKr inhibitor E4031 (1 µM). In conclusion, selective inhibition of physiological late INa shortens the APD, stabilizes ventricular repolarization, and decreases the proarrhythmic potential of pharmacological agents that slow ventricular repolarization. Thus, selective inhibition of late INa may constitute a generalizable approach to stabilize ventricular repolarization and suppress arrhythmogenicity associated with conditions whereby AP or QT intervals are prolonged. NEW & NOTEWORTHY The contribution of physiological late Na+ current in action potential duration (APD) of rabbit cardiac myocytes was estimated. The inhibition of this current prevented the prolongation of APD in rabbit cardiac myocytes, the prolongation of monophasic APD, and generation of arrhythmias in rabbit isolated hearts caused by delayed rectifier K+ current inhibition.
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Affiliation(s)
| | - Cindy Hong Li
- Department of Biology, Gilead Sciences, Fremont, California
| | - Gong-Xin Liu
- Department of Biology, Gilead Sciences, Fremont, California
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ICaL and Ito mediate rate-dependent repolarization in rabbit atrial myocytes. J Physiol Biochem 2017; 74:57-67. [DOI: 10.1007/s13105-017-0603-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Accepted: 12/04/2017] [Indexed: 01/01/2023]
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33
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Late sodium current associated cardiac electrophysiological and mechanical dysfunction. Pflugers Arch 2017; 470:461-469. [DOI: 10.1007/s00424-017-2079-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 09/27/2017] [Accepted: 10/09/2017] [Indexed: 12/19/2022]
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Osadchii OE. Role of abnormal repolarization in the mechanism of cardiac arrhythmia. Acta Physiol (Oxf) 2017; 220 Suppl 712:1-71. [PMID: 28707396 DOI: 10.1111/apha.12902] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
In cardiac patients, life-threatening tachyarrhythmia is often precipitated by abnormal changes in ventricular repolarization and refractoriness. Repolarization abnormalities typically evolve as a consequence of impaired function of outward K+ currents in cardiac myocytes, which may be caused by genetic defects or result from various acquired pathophysiological conditions, including electrical remodelling in cardiac disease, ion channel modulation by clinically used pharmacological agents, and systemic electrolyte disorders seen in heart failure, such as hypokalaemia. Cardiac electrical instability attributed to abnormal repolarization relies on the complex interplay between a provocative arrhythmic trigger and vulnerable arrhythmic substrate, with a central role played by the excessive prolongation of ventricular action potential duration, impaired intracellular Ca2+ handling, and slowed impulse conduction. This review outlines the electrical activity of ventricular myocytes in normal conditions and cardiac disease, describes classical electrophysiological mechanisms of cardiac arrhythmia, and provides an update on repolarization-related surrogates currently used to assess arrhythmic propensity, including spatial dispersion of repolarization, activation-repolarization coupling, electrical restitution, TRIaD (triangulation, reverse use dependence, instability, and dispersion), and the electromechanical window. This is followed by a discussion of the mechanisms that account for the dependence of arrhythmic vulnerability on the location of the ventricular pacing site. Finally, the review clarifies the electrophysiological basis for cardiac arrhythmia produced by hypokalaemia, and gives insight into the clinical importance and pathophysiology of drug-induced arrhythmia, with particular focus on class Ia (quinidine, procainamide) and Ic (flecainide) Na+ channel blockers, and class III antiarrhythmic agents that block the delayed rectifier K+ channel (dofetilide).
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Affiliation(s)
- O. E. Osadchii
- Department of Health Science and Technology; University of Aalborg; Aalborg Denmark
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36
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Osadchii OE. Assessments of the QT/QRS restitution in perfused guinea-pig heart can discriminate safe and arrhythmogenic drugs. J Pharmacol Toxicol Methods 2017; 87:27-37. [PMID: 28552278 DOI: 10.1016/j.vascn.2017.04.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 04/25/2017] [Indexed: 10/19/2022]
Abstract
INTRODUCTION Drug-induced arrhythmia remains a matter of serious clinical concern, partly due to low prognostic value of currently available arrhythmic biomarkers. METHODS This study examined whether arrhythmogenic risks can be predicted through assessments of the rate adaptation of QT interval, ventricular effective refractory period (ERP), or the QT/QRS ratio, in perfused guinea-pig hearts. RESULTS When the maximum restitution slope was taken as a metric of proarrhythmia, neither QT interval nor ERP measurements at progressively increased pacing rates were found to fully discriminate arrhythmogenic drugs (dofetilide, quinidine, flecainide, and procainamide) from those recognized as safe antiarrhythmics (lidocaine and mexiletine). For example, the slope of QT restitution was increased by dofetilide and quinidine, but remained unchanged by flecainide, procainamide, lidocaine, and mexiletine. With ERP rate adaptation, even though the restitution slope was increased by dofetilide, all class I agents reduced the slope value independently of their safety profile. The QRS measurements revealed variable drug effects, ranging from significant use-dependent conduction slowing (flecainide, quinidine, and procainamide) to only modest increase in QRS (lidocaine and mexiletine), or no change at all (dofetilide). However, with the QT/QRS rate adaptation, the restitution slope was significantly increased by all agents which have been reported to produce proarrhythmic effects (dofetilide, quinidine, flecainide, and procainamide), but not changed by lidocaine and mexiletine. DISCUSSION These findings suggest that the slope of the QT/QRS rate adaptation can be considered as a novel electrophysiological biomarker in predicting potential arrhythmic risks associated with pharmacotherapy in cardiac patients.
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Affiliation(s)
- Oleg E Osadchii
- Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen N, Denmark; Department of Health Science and Technology, University of Aalborg, Fredrik Bajers Vej 7E, 9220 Aalborg, Denmark.
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Wei XH, Yu SD, Ren L, Huang SH, Yang QM, Wang P, Chu YP, Yang W, Ding YS, Huo Y, Wu L. Inhibition of late sodium current suppresses calcium-related ventricular arrhythmias by reducing the phosphorylation of CaMK-II and sodium channel expressions. Sci Rep 2017; 7:981. [PMID: 28428622 PMCID: PMC5430524 DOI: 10.1038/s41598-017-01056-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Accepted: 03/20/2017] [Indexed: 12/19/2022] Open
Abstract
Cardiac arrhythmias associated with intracellular calcium inhomeostasis are refractory to antiarrhythmic therapy. We hypothesized that late sodium current (I Na) contributed to the calcium-related arrhythmias. Monophasic action potential duration at 90% completion of repolarization (MAPD90) was significantly increased and ventricular arrhythmias were observed in hearts with increased intracellular calcium concentration ([Ca2+]i) by using Bay K 8644, and the increase became greater in hearts treated with a combination of ATX-II and Bay K 8644 compared to Bay K 8644 alone. The prolongations caused by Bay K 8644 and frequent episodes of ventricular tachycardias, both in absence and presence of ATX-II, were significantly attenuated or abolished by late I Na inhibitors TTX and eleclazine. In rabbit ventricular myocytes, Bay K 8644 increased I CaL density, calcium transient and myocyte contraction. TTX and eleclazine decreased the amplitude of late I Na, the reverse use dependence of MAPD90 at slower heart rate, and attenuated the increase of intracellular calcium transient and myocyte contraction. TTX diminished the phosphorylation of CaMKII-δ and Nav 1.5 in hearts treated with Bay K 8644 and ATX-II. In conclusion, late I Na contributes to ventricular arrhythmias and its inhibition is plausible to treat arrhythmias in hearts with increased [Ca2+]i.
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Affiliation(s)
- Xiao-Hong Wei
- Department of Cardiology, Peking University First Hospital, Beijing, 100034, China.,Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Beijing, 100191, China
| | - Shan-Dong Yu
- Department of Cardiology, Peking University First Hospital, Beijing, 100034, China.,Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Beijing, 100191, China
| | - Lu Ren
- Department of Cardiology, Peking University First Hospital, Beijing, 100034, China.,Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Beijing, 100191, China
| | - Si-Hui Huang
- Department of Cardiology, Peking University First Hospital, Beijing, 100034, China.,Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Beijing, 100191, China
| | - Qiao-Mei Yang
- Department of Cardiology, Peking University First Hospital, Beijing, 100034, China.,Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Beijing, 100191, China
| | - Ping Wang
- Department of Cardiology, Peking University First Hospital, Beijing, 100034, China
| | - Yan-Peng Chu
- Department of Cardiology, Peking University First Hospital, Beijing, 100034, China.,Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Beijing, 100191, China
| | - Wei Yang
- Department of Cardiology, Peking University First Hospital, Beijing, 100034, China.,Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Beijing, 100191, China
| | - Yan-Sheng Ding
- Department of Cardiology, Peking University First Hospital, Beijing, 100034, China.,Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Beijing, 100191, China
| | - Yong Huo
- Department of Cardiology, Peking University First Hospital, Beijing, 100034, China. .,Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Beijing, 100191, China.
| | - Lin Wu
- Department of Cardiology, Peking University First Hospital, Beijing, 100034, China. .,Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Beijing, 100191, China.
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Zhang Y, Wang HM, Wang YZ, Zhang YY, Jin XX, Zhao Y, Wang J, Sun YL, Xue GL, Li PH, Huang QH, Yang BF, Pan ZW. Increment of late sodium currents in the left atrial myocytes and its potential contribution to increased susceptibility of atrial fibrillation in castrated male mice. Heart Rhythm 2017; 14:1073-1080. [PMID: 28185917 DOI: 10.1016/j.hrthm.2017.01.046] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Indexed: 12/20/2022]
Abstract
BACKGROUND The incidence of atrial fibrillation (AF) is correlated with decreased levels of testosterone in elderly men. Late sodium current may exert a role in AF pathogenesis. OBJECTIVE The purpose of this study was to explore the effect of testosterone deficiency on AF susceptibility and the therapeutic effect of late sodium current inhibitors in mice. METHODS Male ICR mice (5 weeks old) were castrated to establish a testosterone deficiency model. One month after castration, dihydrotestosterone 5 mg/kg was administered subcutaneously for 2 months. Serum total testosterone level was assessed by enzyme-linked immunosorbent assay. High-frequency electrical stimulation was used to induce atrial arrhythmias. Whole-cell patch-clamp technique was used to for single-cell electrophysiologic study. RESULTS Serum dihydrotestosterone levels of castration mice declined significantly but recovered with administration of exogenous dihydrotestosterone. In comparison with sham mice, the number of AF episodes significantly increased by 13.5-fold, AF rate increased by 3.75-fold, and AF duration prolonged in castrated mice. Dihydrotestosterone administration alleviated the occurrence of AF. Action potential duration at both 50% and 90% repolarization were markedly increased in castrated mice compared to sham controls. The late sodium current was enhanced in castrated male mice. These alterations were alleviated by treatment with dihydrotestosterone. Systemic application of the INa-L inhibitors ranolazine, eleclazine, and GS967 inhibited the occurrence of AF in castrated mice. CONCLUSION Testosterone deficiency contributed to the increased late sodium current, prolonged action potential repolarization, and increased susceptibility to AF. Blocking of late sodium current is beneficial against the occurrence of AF in castrated mice.
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Affiliation(s)
- Yang Zhang
- Department of Pharmacology (Key Laboratory of Cardiovascular Medicine Research, Ministry of Education, State-Province Key Laboratories of Biomedicine-Pharmaceutics of China), College of Pharmacy Harbin Medical University, Harbin, Heilongjiang, People's Republic of China
| | - Hui-Min Wang
- Department of Pharmacology (Key Laboratory of Cardiovascular Medicine Research, Ministry of Education, State-Province Key Laboratories of Biomedicine-Pharmaceutics of China), College of Pharmacy Harbin Medical University, Harbin, Heilongjiang, People's Republic of China
| | - Ying-Zhe Wang
- Department of Pharmacology (Key Laboratory of Cardiovascular Medicine Research, Ministry of Education, State-Province Key Laboratories of Biomedicine-Pharmaceutics of China), College of Pharmacy Harbin Medical University, Harbin, Heilongjiang, People's Republic of China
| | - Yi-Yuan Zhang
- Department of Pharmacology (Key Laboratory of Cardiovascular Medicine Research, Ministry of Education, State-Province Key Laboratories of Biomedicine-Pharmaceutics of China), College of Pharmacy Harbin Medical University, Harbin, Heilongjiang, People's Republic of China
| | - Xue-Xin Jin
- Department of Pharmacology (Key Laboratory of Cardiovascular Medicine Research, Ministry of Education, State-Province Key Laboratories of Biomedicine-Pharmaceutics of China), College of Pharmacy Harbin Medical University, Harbin, Heilongjiang, People's Republic of China
| | - Yue Zhao
- Department of Pharmacology (Key Laboratory of Cardiovascular Medicine Research, Ministry of Education, State-Province Key Laboratories of Biomedicine-Pharmaceutics of China), College of Pharmacy Harbin Medical University, Harbin, Heilongjiang, People's Republic of China
| | - Jin Wang
- Department of Pharmacology (Key Laboratory of Cardiovascular Medicine Research, Ministry of Education, State-Province Key Laboratories of Biomedicine-Pharmaceutics of China), College of Pharmacy Harbin Medical University, Harbin, Heilongjiang, People's Republic of China
| | - Yi-Lin Sun
- Department of Pharmacology (Key Laboratory of Cardiovascular Medicine Research, Ministry of Education, State-Province Key Laboratories of Biomedicine-Pharmaceutics of China), College of Pharmacy Harbin Medical University, Harbin, Heilongjiang, People's Republic of China
| | - Gen-Long Xue
- Department of Pharmacology (Key Laboratory of Cardiovascular Medicine Research, Ministry of Education, State-Province Key Laboratories of Biomedicine-Pharmaceutics of China), College of Pharmacy Harbin Medical University, Harbin, Heilongjiang, People's Republic of China
| | - Peng-Hui Li
- Department of Pharmacology (Key Laboratory of Cardiovascular Medicine Research, Ministry of Education, State-Province Key Laboratories of Biomedicine-Pharmaceutics of China), College of Pharmacy Harbin Medical University, Harbin, Heilongjiang, People's Republic of China
| | - Qi-He Huang
- Department of Pharmacology (Key Laboratory of Cardiovascular Medicine Research, Ministry of Education, State-Province Key Laboratories of Biomedicine-Pharmaceutics of China), College of Pharmacy Harbin Medical University, Harbin, Heilongjiang, People's Republic of China
| | - Bao-Feng Yang
- Department of Pharmacology (Key Laboratory of Cardiovascular Medicine Research, Ministry of Education, State-Province Key Laboratories of Biomedicine-Pharmaceutics of China), College of Pharmacy Harbin Medical University, Harbin, Heilongjiang, People's Republic of China; Department of Pharmacology and Therapeutics, Melbourne School of Biomedical Sciences, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, Melbourne, Australia
| | - Zhen-Wei Pan
- Department of Pharmacology (Key Laboratory of Cardiovascular Medicine Research, Ministry of Education, State-Province Key Laboratories of Biomedicine-Pharmaceutics of China), College of Pharmacy Harbin Medical University, Harbin, Heilongjiang, People's Republic of China.
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Li W, Yu Y, Hou JW, Zhou ZW, Guo K, Zhang PP, Wang ZQ, Yan JH, Sun J, Zhou Q, Wang YP, Li YG. Larger rate dependence of late sodium current in cardiac Purkinje cells: A potential link to arrhythmogenesis. Heart Rhythm 2016; 14:422-431. [PMID: 27915058 DOI: 10.1016/j.hrthm.2016.11.036] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Indexed: 11/29/2022]
Abstract
BACKGROUND Purkinje cells (PCs) have a steeper rate dependence of repolarization and are more susceptible to arrhythmic activity than do ventricular myocytes (VMs). Late sodium current (INaL) is rate dependent and contributes to rate dependence of repolarization. OBJECTIVE This study sought to test our hypothesis that PCs have a larger rate dependence of INaL, contributing to their steeper rate dependence of repolarization and higher susceptibility to arrhythmic activity, than do VMs. METHODS INaL was recorded in isolated rabbit PCs and VMs with the whole-cell patch clamp technique. Action potential was examined using the microelectrode technique. RESULTS Compared with VMs, PCs exhibited a significantly larger rate dependence of INaL with a larger INaL to basic cycle length (BCL) slope. Moreover, PCs had a larger rate dependence of INaL decay and slower recovery kinetics. Interestingly, the larger rate dependence of INaL matched to a steeper rate dependence of action potential duration (APD) in PCs. The INaL blocker tetrodotoxin significantly blunted, while the INaL enhancer anemone toxin (ATX-II) significantly increased, the rate dependence of INaL and APD in PCs and VMs. In the presence of ATX-II, the rate dependence of INaL in PCs was markedly larger than that in VMs, causing a much steeper rate dependence of APD in PCs. Accordingly, PCs exhibited greater rate-dependent electrical instability and were more prone to ATX-II-induced early afterdepolarizations, which were completely inhibited by the INaL inhibitor ranolazine. CONCLUSION PCs have a significantly larger rate dependence of INaL than do VMs because of distinctive INaL decay and recovery kinetics, which contributes to their larger rate adaptation, and simultaneously predisposes them to a higher risk of arrhythmogenesis.
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Affiliation(s)
- Wei Li
- Department of Cardiology, Xin Hua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Ying Yu
- Department of Cardiology, Xin Hua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Jian-Wen Hou
- Department of Cardiology, Xin Hua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Zhi-Wen Zhou
- Department of Cardiology, Shanghai Xuhui District Central Hospital/Shanghai Clinical Center of Chinese Academy of Sciences, Shanghai, China
| | - Kai Guo
- Department of Cardiology, Xin Hua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Peng-Pai Zhang
- Department of Cardiology, Xin Hua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Zhi-Quan Wang
- Department of Cardiology, Xin Hua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Jian-Hua Yan
- Department of Cardiology, Xin Hua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Jian Sun
- Department of Cardiology, Xin Hua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Qing Zhou
- Department of Cardiology, Xin Hua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yue-Peng Wang
- Department of Cardiology, Xin Hua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yi-Gang Li
- Department of Cardiology, Xin Hua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China.
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Potet F, Vanoye CG, George AL. Use-Dependent Block of Human Cardiac Sodium Channels by GS967. Mol Pharmacol 2016; 90:52-60. [PMID: 27136942 DOI: 10.1124/mol.116.103358] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Accepted: 04/29/2016] [Indexed: 01/22/2023] Open
Abstract
GS-458967, 6-(4-(Trifluoromethoxy)phenyl)-3-(trifluoromethyl)-[1,2,4]triazolo[4,3-a]pyridine (GS967) is a recently described, novel, sodium channel inhibitor exhibiting potent antiarrhythmic effects in various in vitro and in vivo models. The antiarrhythmic mechanism has been attributed to preferential suppression of late sodium current. However, there has been no reported systematic investigation of the effects of this compound on isolated sodium channels. Here, we examined the effects of GS967 on peak (INaP) and late (INaL) sodium current recorded from cells that heterologously expressed human cardiac voltage-gated sodium channel, the principle cardiac sodium channel. As previously described, we observed that GS967 exerted tonic block of INaL (63%) to a significantly greater extent than INaP (19%). However, GS967 also caused a reduction of INaP in a frequency-dependent manner, consistent with use-dependent block (UDB). GS967 evoked more potent UDB of INaP (IC50 = 0.07 µM) than ranolazine (16 µM) and lidocaine (17 µM). Use-dependent block was best explained by a significant slowing of recovery from fast and slow inactivation with a significant enhancement of slow inactivation in the presence of GS967. Furthermore, GS967 was found to exert these same effects on a prototypical long QT syndrome mutation (delKPQ). An engineered mutation at an interaction site for local anesthetic agents (F1760A) partially attenuated the effect of GS967 on UDB, but had no effect on tonic INaL block. We conclude that GS967 is a preferential inhibitor of INaL, but it also exerts previously unreported strong effects on slow inactivation and recovery from inactivation, resulting in substantial UDB that is not entirely dependent on a known interaction site for local anesthetic agents.
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Affiliation(s)
- Franck Potet
- Department of Pharmacology, Northwestern University, Feinberg School of Medicine, Chicago, Illinois
| | - Carlos G Vanoye
- Department of Pharmacology, Northwestern University, Feinberg School of Medicine, Chicago, Illinois
| | - Alfred L George
- Department of Pharmacology, Northwestern University, Feinberg School of Medicine, Chicago, Illinois
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Hou JW, Li W, Guo K, Chen XM, Chen YH, Li CY, Zhao BC, Zhao J, Wang H, Wang YP, Li YG. Antiarrhythmic effects and potential mechanism of WenXin KeLi in cardiac Purkinje cells. Heart Rhythm 2016; 13:973-82. [DOI: 10.1016/j.hrthm.2015.12.023] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Indexed: 10/22/2022]
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α1-Syntrophin Variant Identified in Drug-Induced Long QT Syndrome Increases Late Sodium Current. PLoS One 2016; 11:e0152355. [PMID: 27028743 PMCID: PMC4814026 DOI: 10.1371/journal.pone.0152355] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2015] [Accepted: 03/14/2016] [Indexed: 12/19/2022] Open
Abstract
Drug-induced long-QT syndrome (diLQTS) is often due to drug block of IKr, especially in genetically susceptible patients with subclinical mutations in the IKr-encoding KCHN2. Few variants in the cardiac NaV1.5 Na+ channel complex have been associated with diLQTS. We tested whether a novel SNTA1 (α1-syntrophin) variant (p.E409Q) found in a patient with diLQTS increases late sodium current (INa-L), thereby providing a disease mechanism. Electrophysiological studies were performed in HEK293T cells co-expressing human NaV1.5/nNOS/PMCA4b with either wild type (WT) or SNTA1 variants (A390V-previously reported in congenital LQTS; and E409Q); and in adult rat ventricular cardiomyocytes infected with SNTA1 expressing adenoviruses (WT or one of the two SNTA1 variants). In HEK293T cells and in cardiomyocytes, there was no significant difference in the peak INa densities among the SNTA1 WT and variants. However, both variants increased INa-L (% of peak current) in HEK293T cells (0.58±0.10 in WT vs. 0.90±0.11 in A390V, p = 0.048; vs. 0.88±0.07 in E409Q, p = 0.023). In cardiomyocytes, INa-L was significantly increased by E409Q, but not by A390V compared to WT (0.49±0.14 in WT vs.0.94±0.23 in A390V, p = 0.099; vs. 1.12±0.24 in E409Q, p = 0.019). We demonstrated that a novel SNTA1 variant is likely causative for diLQTS by augmenting INa-L. These data suggest that variants within the NaV1.5-interacting α1-syntrophin are a potential mechanism for diLQTS, thereby expanding the concept that variants within congenital LQTS loci can cause diLQTS.
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Pueyo E, Dangerfield CE, Britton OJ, Virág L, Kistamás K, Szentandrássy N, Jost N, Varró A, Nánási PP, Burrage K, Rodríguez B. Experimentally-Based Computational Investigation into Beat-To-Beat Variability in Ventricular Repolarization and Its Response to Ionic Current Inhibition. PLoS One 2016; 11:e0151461. [PMID: 27019293 PMCID: PMC4809506 DOI: 10.1371/journal.pone.0151461] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2015] [Accepted: 02/29/2016] [Indexed: 11/18/2022] Open
Abstract
Beat-to-beat variability in repolarization (BVR) has been proposed as an arrhythmic risk marker for disease and pharmacological action. The mechanisms are unclear but BVR is thought to be a cell level manifestation of ion channel stochasticity, modulated by cell-to-cell differences in ionic conductances. In this study, we describe the construction of an experimentally-calibrated set of stochastic cardiac cell models that captures both BVR and cell-to-cell differences in BVR displayed in isolated canine action potential measurements using pharmacological agents. Simulated and experimental ranges of BVR are compared in control and under pharmacological inhibition, and the key ionic currents determining BVR under physiological and pharmacological conditions are identified. Results show that the 4-aminopyridine-sensitive transient outward potassium current, Ito1, is a fundamental driver of BVR in control and upon complete inhibition of the slow delayed rectifier potassium current, IKs. In contrast, IKs and the L-type calcium current, ICaL, become the major contributors to BVR upon inhibition of the fast delayed rectifier potassium current, IKr. This highlights both IKs and Ito1 as key contributors to repolarization reserve. Partial correlation analysis identifies the distribution of Ito1 channel numbers as an important independent determinant of the magnitude of BVR and drug-induced change in BVR in control and under pharmacological inhibition of ionic currents. Distributions in the number of IKs and ICaL channels only become independent determinants of the magnitude of BVR upon complete inhibition of IKr. These findings provide quantitative insights into the ionic causes of BVR as a marker for repolarization reserve, both under control condition and pharmacological inhibition.
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Affiliation(s)
- E. Pueyo
- Biomedical Research Networking Centre on Bioengineering, Biomaterials and Nanomedicine, University of Zaragoza, Zaragoza, Spain
- Biosignal Interpretation and Computational Simulation Group, I3A, IIS, Aragón, University of Zaragoza, Zaragoza, Spain
- * E-mail:
| | - C. E. Dangerfield
- Department of Computer Science, University of Oxford, Oxford, United Kingdom
| | - O. J. Britton
- Department of Computer Science, University of Oxford, Oxford, United Kingdom
| | - L. Virág
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
- MTA-SZTE Research Group of Cardiovascular Pharmacology, Hungarian Academy of Sciences, Szeged, Hungary
| | - K. Kistamás
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - N. Szentandrássy
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- Department of Dental Physiology and Pharmacology, Faculty of Dentistry, University of Debrecen, Debrecen, Hungary
| | - N. Jost
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
- MTA-SZTE Research Group of Cardiovascular Pharmacology, Hungarian Academy of Sciences, Szeged, Hungary
| | - A. Varró
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
- MTA-SZTE Research Group of Cardiovascular Pharmacology, Hungarian Academy of Sciences, Szeged, Hungary
| | - P. P. Nánási
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- Department of Dental Physiology and Pharmacology, Faculty of Dentistry, University of Debrecen, Debrecen, Hungary
| | - K. Burrage
- Department of Computer Science, University of Oxford, Oxford, United Kingdom
- School of Mathematical Sciences, Queensland University of Technology, Brisbane, Queensland, Australia
- ARC Centre of Excellence for Mathematical and Statistical Frontiers, Queensland University of Technology, Brisbane, Queensland, Australia
| | - B. Rodríguez
- Department of Computer Science, University of Oxford, Oxford, United Kingdom
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McCauley M, Vallabhajosyula S, Darbar D. Proarrhythmic and Torsadogenic Effects of Potassium Channel Blockers in Patients. Card Electrophysiol Clin 2016; 8:481-93. [PMID: 27261836 DOI: 10.1016/j.ccep.2016.02.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The most common arrhythmia requiring drug treatment is atrial fibrillation (AF), which affects 2 to 5 million Americans and continues to be a major cause of morbidity and increased mortality. Despite recent advances in catheter-based and surgical therapies, antiarrhythmic drugs continue to be the mainstay of therapy for most patients with symptomatic AF. However, many antiarrhythmics block the rapid component of the cardiac delayed rectifier potassium current (IKr) as a major mechanism of action, and marked QT prolongation and pause-dependent polymorphic ventricular tachycardia (torsades de pointes) are major class toxicities.
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Affiliation(s)
- Mark McCauley
- Division of Cardiology, Department of Medicine, University of Illinois at Chicago, 840 South Wood Street, Suite 920 (MC715), Chicago, IL 60612, USA
| | - Sharath Vallabhajosyula
- Division of Cardiology, Department of Medicine, University of Illinois at Chicago, 840 South Wood Street, Suite 920 (MC715), Chicago, IL 60612, USA
| | - Dawood Darbar
- Division of Cardiology, Department of Medicine, University of Illinois at Chicago, 840 South Wood Street, Suite 920 (MC715), Chicago, IL 60612, USA.
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45
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Sorrentino A, Signore S, Qanud K, Borghetti G, Meo M, Cannata A, Zhou Y, Wybieralska E, Luciani M, Kannappan R, Zhang E, Matsuda A, Webster A, Cimini M, Kertowidjojo E, D'Alessandro DA, Wunimenghe O, Michler RE, Royer C, Goichberg P, Leri A, Barrett EG, Anversa P, Hintze TH, Rota M. Myocyte repolarization modulates myocardial function in aging dogs. Am J Physiol Heart Circ Physiol 2016; 310:H873-90. [PMID: 26801307 DOI: 10.1152/ajpheart.00682.2015] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Accepted: 12/24/2015] [Indexed: 12/19/2022]
Abstract
Studies of myocardial aging are complex and the mechanisms involved in the deterioration of ventricular performance and decreased functional reserve of the old heart remain to be properly defined. We have studied a colony of beagle dogs from 3 to 14 yr of age kept under a highly regulated environment to define the effects of aging on the myocardium. Ventricular, myocardial, and myocyte function, together with anatomical and structural properties of the organ and cardiomyocytes, were evaluated. Ventricular hypertrophy was not observed with aging and the structural composition of the myocardium was modestly affected. Alterations in the myocyte compartment were identified in aged dogs, and these factors negatively interfere with the contractile reserve typical of the young heart. The duration of the action potential is prolonged in old cardiomyocytes contributing to the slower electrical recovery of the myocardium. Also, the remodeled repolarization of cardiomyocytes with aging provides inotropic support to the senescent muscle but compromises its contractile reserve, rendering the old heart ineffective under conditions of high hemodynamic demand. The defects in the electrical and mechanical properties of cardiomyocytes with aging suggest that this cell population is an important determinant of the cardiac senescent phenotype. Collectively, the delayed electrical repolarization of aging cardiomyocytes may be viewed as a critical variable of the aging myopathy and its propensity to evolve into ventricular decompensation under stressful conditions.
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Affiliation(s)
- Andrea Sorrentino
- Departments of Anesthesia and Medicine, and Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Sergio Signore
- Departments of Anesthesia and Medicine, and Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Khaled Qanud
- Department of Physiology, New York Medical College, Valhalla, New York
| | - Giulia Borghetti
- Departments of Anesthesia and Medicine, and Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Marianna Meo
- Departments of Anesthesia and Medicine, and Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Antonio Cannata
- Departments of Anesthesia and Medicine, and Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Yu Zhou
- Departments of Anesthesia and Medicine, and Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Ewa Wybieralska
- Departments of Anesthesia and Medicine, and Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Marco Luciani
- Departments of Anesthesia and Medicine, and Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Ramaswamy Kannappan
- Departments of Anesthesia and Medicine, and Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Eric Zhang
- Departments of Anesthesia and Medicine, and Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Alex Matsuda
- Departments of Anesthesia and Medicine, and Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Andrew Webster
- Departments of Anesthesia and Medicine, and Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Maria Cimini
- Departments of Anesthesia and Medicine, and Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | | | | | - Oriyanhan Wunimenghe
- Department of Cardiovascular and Thoracic Surgery, Montefiore Medical Center, Albert Einstein College of Medicine, New York, New York; and
| | - Robert E Michler
- Department of Cardiovascular and Thoracic Surgery, Montefiore Medical Center, Albert Einstein College of Medicine, New York, New York; and
| | | | - Polina Goichberg
- Departments of Anesthesia and Medicine, and Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Annarosa Leri
- Departments of Anesthesia and Medicine, and Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Edward G Barrett
- Lovelace Respiratory Research Institute, Albuquerque, New Mexico
| | - Piero Anversa
- Departments of Anesthesia and Medicine, and Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Thomas H Hintze
- Department of Physiology, New York Medical College, Valhalla, New York
| | - Marcello Rota
- Departments of Anesthesia and Medicine, and Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts; Department of Physiology, New York Medical College, Valhalla, New York;
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Champeroux P, Le Guennec JY, Jude S, Laigot C, Maurin A, Sola ML, Fowler JSL, Richard S, Thireau J. The high frequency relationship: implications for torsadogenic hERG blockers. Br J Pharmacol 2016; 173:601-12. [PMID: 26589499 DOI: 10.1111/bph.13391] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 11/11/2015] [Accepted: 11/17/2015] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND AND PURPOSE Ventricular arrhythmias induced by human ether-a-go-go related gene (hERG; Kv 11.1 channel) blockers are a consequence of alterations in ventricular repolarisation in association with high-frequency (HF) oscillations, which act as a primary trigger; the autonomic nervous system plays a modulatory role. In the present study, we investigated the role of β1 -adrenoceptors in the HF relationship between magnitude of heart rate and QT interval changes within discrete 10 s intervals (sorted into 5 bpm heart rate increments) and its implications for torsadogenic hERG blockers. EXPERIMENTAL APPROACH The HF relationship was studied under conditions of autonomic blockade with atenolol (β1 -adrenoceptor blocker) in the absence or presence of five hERG blockers in beagle dogs. In total, the effects of 14 hERG blockers on the HF relationship were investigated. KEY RESULTS All the torsadogenic hERG blockers tested caused a vertical shift in the HF relationship, while hERG blockers associated with a low risk of Torsades de Pointes did not cause any vertical shift. Atenolol completely prevented the effects four torsadogenic agents (quinidine, thioridazine, risperidone and terfenadine) on the HF relationship, but only partially reduced those of dofetilide, leading to the characterization of two types of torsadogenic agent. CONCLUSIONS AND IMPLICATIONS Analysis of the vertical shift in the HF relationship demonstrated that signs of transient sympathetic activation during HF oscillations in the presence of torsadogenic hERG blockers are mediated by β1 -adrenoceptors. We suggest the HF relationship as a new biomarker for assessing Torsades de pointes liability, with potential implications in both preclinical studies and the clinic.
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Affiliation(s)
- P Champeroux
- Centre de Recherches Biologiques, CERB, Chemin de Montifault, 18800, Baugy, France
| | - J Y Le Guennec
- Laboratoire PHYMEDEXP, Physiologie et Médecine Expérimentale, Cœur et Muscles, INSERM U1046, CNRS UMR 9214, Université de Montpellier, CHU Arnaud de Villeneuve, 371 Avenue du doyen G. Giraud, 34295, Montpellier cedex 05, France
| | - S Jude
- Centre de Recherches Biologiques, CERB, Chemin de Montifault, 18800, Baugy, France
| | - C Laigot
- Centre de Recherches Biologiques, CERB, Chemin de Montifault, 18800, Baugy, France
| | - A Maurin
- Centre de Recherches Biologiques, CERB, Chemin de Montifault, 18800, Baugy, France
| | - M L Sola
- Centre de Recherches Biologiques, CERB, Chemin de Montifault, 18800, Baugy, France
| | - J S L Fowler
- Centre de Recherches Biologiques, CERB, Chemin de Montifault, 18800, Baugy, France
| | - S Richard
- Centre de Recherches Biologiques, CERB, Chemin de Montifault, 18800, Baugy, France
| | - J Thireau
- Laboratoire PHYMEDEXP, Physiologie et Médecine Expérimentale, Cœur et Muscles, INSERM U1046, CNRS UMR 9214, Université de Montpellier, CHU Arnaud de Villeneuve, 371 Avenue du doyen G. Giraud, 34295, Montpellier cedex 05, France
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Clancy CE, Chen-Izu Y, Bers DM, Belardinelli L, Boyden PA, Csernoch L, Despa S, Fermini B, Hool LC, Izu L, Kass RS, Lederer WJ, Louch WE, Maack C, Matiazzi A, Qu Z, Rajamani S, Rippinger CM, Sejersted OM, O'Rourke B, Weiss JN, Varró A, Zaza A. Deranged sodium to sudden death. J Physiol 2015; 593:1331-45. [PMID: 25772289 DOI: 10.1113/jphysiol.2014.281204] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Accepted: 10/14/2014] [Indexed: 12/19/2022] Open
Abstract
In February 2014, a group of scientists convened as part of the University of California Davis Cardiovascular Symposium to bring together experimental and mathematical modelling perspectives and discuss points of consensus and controversy on the topic of sodium in the heart. This paper summarizes the topics of presentation and discussion from the symposium, with a focus on the role of aberrant sodium channels and abnormal sodium homeostasis in cardiac arrhythmias and pharmacotherapy from the subcellular scale to the whole heart. Two following papers focus on Na(+) channel structure, function and regulation, and Na(+)/Ca(2+) exchange and Na(+)/K(+) ATPase. The UC Davis Cardiovascular Symposium is a biannual event that aims to bring together leading experts in subfields of cardiovascular biomedicine to focus on topics of importance to the field. The focus on Na(+) in the 2014 symposium stemmed from the multitude of recent studies that point to the importance of maintaining Na(+) homeostasis in the heart, as disruption of homeostatic processes are increasingly identified in cardiac disease states. Understanding how disruption in cardiac Na(+)-based processes leads to derangement in multiple cardiac components at the level of the cell and to then connect these perturbations to emergent behaviour in the heart to cause disease is a critical area of research. The ubiquity of disruption of Na(+) channels and Na(+) homeostasis in cardiac disorders of excitability and mechanics emphasizes the importance of a fundamental understanding of the associated mechanisms and disease processes to ultimately reveal new targets for human therapy.
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Affiliation(s)
- Colleen E Clancy
- Department of Pharmacology, University of California, Davis, Genome Building Rm 3503, Davis, CA, 95616-8636, USA
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48
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Winter J, Shattock MJ. Geometrical considerations in cardiac electrophysiology and arrhythmogenesis. Europace 2015; 18:320-31. [PMID: 26585597 DOI: 10.1093/europace/euv307] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 08/14/2015] [Indexed: 11/14/2022] Open
Abstract
The rate of repolarization (RRepol) and so the duration of the cardiac action potential are determined by the balance of inward and outward currents across the cardiac membrane (net ionic current). Plotting action potential duration (APD) as a function of the RRepol reveals an inverse non-linear relationship, arising from the geometric association between these two factors. From the RRepol-APD relationship, it can be observed that a longer action potential will exhibit a greater propensity to shorten, or prolong, for a given change in the RRepol (i.e. net ionic current), when compared with one that is initially shorter. This observation has recently been used to explain why so many interventions that prolong the action potential exert a greater effect at slow rates (reverse rate-dependence). In this article, we will discuss the broader implications of this simple principle and examine how common experimental observations on the electrical behaviour of the myocardium may be explained in terms of the RRepol-APD relationship. An argument is made, with supporting published evidence, that the non-linear relationship between the RRepol and APD is a fundamental, and largely overlooked, property of the myocardium. The RRepol-APD relationship appears to explain why interventions and disease with seemingly disparate mechanisms of action have similar electrophysiological consequences. Furthermore, the RRepol-APD relationship predicts that prolongation of the action potential, by slowing repolarization, will promote conditions of dynamic electrical instability, exacerbating several electrophysiological phenomena associated with arrhythmogenesis, namely, the rate dependence of dispersion of repolarization, APD restitution, and electrical alternans.
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Affiliation(s)
- James Winter
- Cardiovascular Division, The Rayne Institute, 4th Floor, Lambeth Wing, St Thomas' Hospital, King's College London, London SE1 7EH, UK
| | - Michael J Shattock
- Cardiovascular Division, The Rayne Institute, 4th Floor, Lambeth Wing, St Thomas' Hospital, King's College London, London SE1 7EH, UK
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49
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Signore S, Sorrentino A, Borghetti G, Cannata A, Meo M, Zhou Y, Kannappan R, Pasqualini F, O'Malley H, Sundman M, Tsigkas N, Zhang E, Arranto C, Mangiaracina C, Isobe K, Sena BF, Kim J, Goichberg P, Nahrendorf M, Isom LL, Leri A, Anversa P, Rota M. Late Na(+) current and protracted electrical recovery are critical determinants of the aging myopathy. Nat Commun 2015; 6:8803. [PMID: 26541940 PMCID: PMC4638135 DOI: 10.1038/ncomms9803] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 10/02/2015] [Indexed: 12/19/2022] Open
Abstract
The aging myopathy manifests itself with diastolic dysfunction and preserved ejection fraction. We raised the possibility that, in a mouse model of physiological aging, defects in electromechanical properties of cardiomyocytes are important determinants of the diastolic characteristics of the myocardium, independently from changes in structural composition of the muscle and collagen framework. Here we show that an increase in the late Na(+) current (INaL) in aging cardiomyocytes prolongs the action potential (AP) and influences temporal kinetics of Ca(2+) cycling and contractility. These alterations increase force development and passive tension. Inhibition of INaL shortens the AP and corrects dynamics of Ca(2+) transient, cell contraction and relaxation. Similarly, repolarization and diastolic tension of the senescent myocardium are partly restored. Thus, INaL offers inotropic support, but negatively interferes with cellular and ventricular compliance, providing a new perspective of the biology of myocardial aging and the aetiology of the defective cardiac performance in the elderly.
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Affiliation(s)
- Sergio Signore
- Departments of Anesthesia and Medicine and Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, 20 Shattuck Street, Boston, Massachusetts 02115, USA
| | - Andrea Sorrentino
- Departments of Anesthesia and Medicine and Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, 20 Shattuck Street, Boston, Massachusetts 02115, USA
| | - Giulia Borghetti
- Departments of Anesthesia and Medicine and Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, 20 Shattuck Street, Boston, Massachusetts 02115, USA
| | - Antonio Cannata
- Departments of Anesthesia and Medicine and Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, 20 Shattuck Street, Boston, Massachusetts 02115, USA
| | - Marianna Meo
- Departments of Anesthesia and Medicine and Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, 20 Shattuck Street, Boston, Massachusetts 02115, USA
| | - Yu Zhou
- Departments of Anesthesia and Medicine and Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, 20 Shattuck Street, Boston, Massachusetts 02115, USA
| | - Ramaswamy Kannappan
- Departments of Anesthesia and Medicine and Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, 20 Shattuck Street, Boston, Massachusetts 02115, USA
| | - Francesco Pasqualini
- Departments of Anesthesia and Medicine and Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, 20 Shattuck Street, Boston, Massachusetts 02115, USA
| | - Heather O'Malley
- Department of Pharmacology, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Mark Sundman
- Departments of Anesthesia and Medicine and Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, 20 Shattuck Street, Boston, Massachusetts 02115, USA
| | - Nikolaos Tsigkas
- Departments of Anesthesia and Medicine and Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, 20 Shattuck Street, Boston, Massachusetts 02115, USA
| | - Eric Zhang
- Departments of Anesthesia and Medicine and Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, 20 Shattuck Street, Boston, Massachusetts 02115, USA
| | - Christian Arranto
- Departments of Anesthesia and Medicine and Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, 20 Shattuck Street, Boston, Massachusetts 02115, USA
| | - Chiara Mangiaracina
- Departments of Anesthesia and Medicine and Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, 20 Shattuck Street, Boston, Massachusetts 02115, USA
| | - Kazuya Isobe
- Departments of Anesthesia and Medicine and Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, 20 Shattuck Street, Boston, Massachusetts 02115, USA
| | - Brena F Sena
- Center for Systems Biology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA
| | - Junghyun Kim
- Departments of Anesthesia and Medicine and Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, 20 Shattuck Street, Boston, Massachusetts 02115, USA
| | - Polina Goichberg
- Departments of Anesthesia and Medicine and Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, 20 Shattuck Street, Boston, Massachusetts 02115, USA
| | - Matthias Nahrendorf
- Center for Systems Biology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA
| | - Lori L Isom
- Department of Pharmacology, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Annarosa Leri
- Departments of Anesthesia and Medicine and Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, 20 Shattuck Street, Boston, Massachusetts 02115, USA
| | - Piero Anversa
- Departments of Anesthesia and Medicine and Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, 20 Shattuck Street, Boston, Massachusetts 02115, USA
| | - Marcello Rota
- Departments of Anesthesia and Medicine and Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, 20 Shattuck Street, Boston, Massachusetts 02115, USA
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50
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Antoons G, Johnson DM, Dries E, Santiago DJ, Ozdemir S, Lenaerts I, Beekman JDM, Houtman MJC, Sipido KR, Vos MA. Calcium release near L-type calcium channels promotes beat-to-beat variability in ventricular myocytes from the chronic AV block dog. J Mol Cell Cardiol 2015; 89:326-34. [PMID: 26454162 DOI: 10.1016/j.yjmcc.2015.10.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Revised: 09/08/2015] [Accepted: 10/06/2015] [Indexed: 11/25/2022]
Abstract
Beat-to-beat variability of ventricular repolarization (BVR) has been proposed as a strong predictor of Torsades de Pointes (TdP). BVR is also observed at the myocyte level, and a number of studies have shown the importance of calcium handling in influencing this parameter. The chronic AV block (CAVB) dog is a model of TdP arrhythmia in cardiac hypertrophy, and myocytes from these animals show extensive remodeling, including of Ca(2+) handling. This remodeling process also leads to increased BVR. We aimed to determine the role that (local) Ca(2+) handling plays in BVR. In isolated LV myocytes an exponential relationship was observed between BVR magnitude and action potential duration (APD) at baseline. Inhibition of Ca(2+) release from sarcoplasmic reticulum (SR) with thapsigargin resulted in a reduction of [Ca(2+)]i, and of both BVR and APD. Increasing ICaL in the presence of thapsigargin restored APD but BVR remained low. In contrast, increasing ICaL with preserved Ca(2+) release increased both APD and BVR. Inhibition of Ca(2+) release with caffeine, as with thapsigargin, reduced BVR despite maintained APD. Simultaneous inhibition of Na(+)/Ca(2+) exchange and ICaL decreased APD and BVR to similar degrees, whilst increasing diastolic Ca(2+). Buffering of Ca(2+) transients with BAPTA reduced BVR for a given APD to a greater extent than buffering with EGTA, suggesting subsarcolemmal Ca(2+) transients modulated BVR to a larger extent than the cytosolic Ca(2+) transient. In conclusion, BVR in hypertrophied dog myocytes, at any APD, is strongly dependent on SR Ca(2+) release, which may act through modulation of the l-type Ca(2+) current in a subsarcolemmal microdomain.
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Affiliation(s)
- Gudrun Antoons
- Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven (University of Leuven), Leuven, Belgium; Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, University of Utrecht, Utrecht, The Netherlands; Department of Physiology, Maastricht University, Maastricht, The Netherlands
| | - Daniel M Johnson
- Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven (University of Leuven), Leuven, Belgium
| | - Eef Dries
- Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven (University of Leuven), Leuven, Belgium
| | - Demetrio J Santiago
- Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven (University of Leuven), Leuven, Belgium
| | - Semir Ozdemir
- Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven (University of Leuven), Leuven, Belgium; Department of Biophysics, Akdeniz University, Antalya, Turkey
| | - Ilse Lenaerts
- Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven (University of Leuven), Leuven, Belgium
| | - Jet D M Beekman
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, University of Utrecht, Utrecht, The Netherlands
| | - Marien J C Houtman
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, University of Utrecht, Utrecht, The Netherlands
| | - Karin R Sipido
- Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven (University of Leuven), Leuven, Belgium.
| | - Marc A Vos
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, University of Utrecht, Utrecht, The Netherlands
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