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Aubin Vega M, Girault A, Adam D, Chebli J, Privé A, Maillé É, Robichaud A, Brochiero E. Impact of KvLQT1 potassium channel modulation on alveolar fluid homeostasis in an animal model of thiourea-induced lung edema. Front Physiol 2023; 13:1069466. [PMID: 36699692 PMCID: PMC9868633 DOI: 10.3389/fphys.2022.1069466] [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: 10/13/2022] [Accepted: 12/19/2022] [Indexed: 01/11/2023] Open
Abstract
Alveolar ion and fluid absorption is essential for lung homeostasis in healthy conditions as well as for the resorption of lung edema, a key feature of acute respiratory distress syndrome. Liquid absorption is driven by active transepithelial sodium transport, through apical ENaC Na+ channels and basolateral Na+/K+-ATPase. Our previous work unveiled that KvLQT1 K+ channels also participate in the control of Na+/liquid absorption in alveolar epithelial cells. Our aim was to further investigate the function of KvLQT1 channels and their interplay with other channels/transporters involved in ion/liquid transport in vivo using adult wild-type (WT) and KvLQT1 knock-out (KO) mice under physiological conditions and after thiourea-induced lung edema. A slight but significant increase in water lung content (WLC) was observed in naïve KvLQT1-KO mice, relative to WT littermates, whereas lung function was generally preserved and histological structure unaltered. Following thiourea-induced lung edema, KvLQT1-KO did not worsen WLC or lung function. Similarly, lung edema was not aggravated by the administration of a KvLQT1 inhibitor (chromanol). However, KvLQT1 activation (R-L3) significantly reduced WLC in thiourea-challenged WT mice. The benefits of R-L3 were prevented in KO or chromanol-treated WT mice. Furthermore, R-L3 treatment had no effect on thiourea-induced endothelial barrier alteration but restored or enhanced the levels of epithelial alveolar AQP5, Na+/K+-ATPase, and ENaC expressions. Altogether, the results indicate the benefits of KvLQT1 activation in the resolution of lung edema, probably through the observed up-regulation of epithelial alveolar channels/transporters involved in ion/water transport.
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Affiliation(s)
- Mélissa Aubin Vega
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), Montréal, QC, Canada,Département de Médecine, Université de Montréal, Montréal, QC, Canada
| | - Alban Girault
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), Montréal, QC, Canada,Département de Médecine, Université de Montréal, Montréal, QC, Canada,Laboratoire de Physiologie Cellulaire et Moléculaire (LPCM), Amiens, France
| | - Damien Adam
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), Montréal, QC, Canada,Département de Médecine, Université de Montréal, Montréal, QC, Canada
| | - Jasmine Chebli
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), Montréal, QC, Canada,Département de Médecine, Université de Montréal, Montréal, QC, Canada
| | - Anik Privé
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), Montréal, QC, Canada
| | - Émilie Maillé
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), Montréal, QC, Canada
| | | | - Emmanuelle Brochiero
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), Montréal, QC, Canada,Département de Médecine, Université de Montréal, Montréal, QC, Canada,*Correspondence: Emmanuelle Brochiero,
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Song Y, Guo T, Jiang Y, Zhu M, Wang H, Lu W, Jiang M, Qi M, Lan F, Cui M. KCNQ1-deficient and KCNQ1-mutant human embryonic stem cell-derived cardiomyocytes for modeling QT prolongation. Stem Cell Res Ther 2022; 13:287. [PMID: 35765105 PMCID: PMC9241307 DOI: 10.1186/s13287-022-02964-3] [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: 01/11/2022] [Accepted: 03/20/2022] [Indexed: 11/10/2022] Open
Abstract
Background The slowly activated delayed rectifier potassium current (IKs) mediated by the KCNQ1 gene is one of the main currents involved in repolarization. KCNQ1 mutation can result in long-QT syndrome type 1 (LQT1). IKs does not participate in repolarization in mice; thus, no good model is currently available for research on the mechanism of and drug screening for LQT1. In this study, we established a KCNQ1-deficient human cardiomyocyte (CM) model and performed a series of microelectrode array (MEA) detection experiments on KCNQ1-mutant CMs constructed in other studies to explore the pathogenic mechanism of KCNQ1 deletion and mutation and perform drug screening. Method KCNQ1 was knocked out in human embryonic stem cell (hESC) H9 line using the CRISPR/cas9 system. KCNQ1-deficient and KCNQ1-mutant hESCs were differentiated into CMs through a chemically defined differentiation protocol. Subsequently, high-throughput MEA analysis and drug intervention were performed to determine the electrophysiological characteristics of KCNQ1-deficient and KCNQ1-mutant CMs. Results During high-throughput MEA analysis, the electric field potential and action potential durations in KCNQ1-deficient CMs were significantly longer than those in wild-type CMs. KCNQ1-deficient CMs also showed an irregular rhythm. Furthermore, KCNQ1-deficient and KCNQ1-mutant CMs showed different responses to different drug treatments, which reflected the differences in their pathogenic mechanisms. Conclusion We established a human CM model with KCNQ1 deficiency showing a prolonged QT interval and an irregular heart rhythm. Further, we used various drugs to treat KCNQ1-deficient and KCNQ1-mutant CMs, and the three models showed different responses to these drugs. These models can be used as important tools for studying the different pathogenic mechanisms of KCNQ1 mutation and the relationship between the genotype and phenotype of KCNQ1, thereby facilitating drug development. Supplementary Information The online version contains supplementary material available at 10.1186/s13287-022-02964-3.
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Affiliation(s)
- Yuanxiu Song
- Department of Cardiology, Peking University Third Hospital, 49 Huayuan North Road, Haidian District, Beijing, 100191, China
| | - Tianwei Guo
- Beijing Lab for Cardiovascular Precision Medicine, Anzhen Hospital, Capital Medical University, Beijing, 100029, China
| | - Youxu Jiang
- Department of Cardiology, The Second Affiliated Hospital of Zhengzhou University, Jingba Road, Zhengzhou, 450053, China
| | - Min Zhu
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100037, China
| | - Hongyue Wang
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100037, China
| | - Wenjing Lu
- Shenzhen Key Laboratory of Cardiovascular Disease, Fuwai Hospital Chinese Academy of Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Shenzhen, 518057, China
| | - Mengqi Jiang
- Department of Cell Biology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Man Qi
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100037, China
| | - Feng Lan
- Shenzhen Key Laboratory of Cardiovascular Disease, Fuwai Hospital Chinese Academy of Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Shenzhen, 518057, China.
| | - Ming Cui
- Department of Cardiology, Peking University Third Hospital, 49 Huayuan North Road, Haidian District, Beijing, 100191, China.
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Loss of type 9 adenylyl cyclase triggers reduced phosphorylation of Hsp20 and diastolic dysfunction. Sci Rep 2017; 7:5522. [PMID: 28717248 PMCID: PMC5514062 DOI: 10.1038/s41598-017-05816-w] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 06/05/2017] [Indexed: 01/16/2023] Open
Abstract
Adenylyl cyclase type 9 (AC9) is found tightly associated with the scaffolding protein Yotiao and the IKs ion channel in heart. But apart from potential IKs regulation, physiological roles for AC9 are unknown. We show that loss of AC9 in mice reduces less than 3% of total AC activity in heart but eliminates Yotiao-associated AC activity. AC9−/− mice exhibit no structural abnormalities but show a significant bradycardia, consistent with AC9 expression in sinoatrial node. Global changes in PKA phosphorylation patterns are not altered in AC9−/− heart, however, basal phosphorylation of heat shock protein 20 (Hsp20) is significantly decreased. Hsp20 binds AC9 in a Yotiao-independent manner and deletion of AC9 decreases Hsp20-associated AC activity in heart. In addition, expression of catalytically inactive AC9 in neonatal cardiomyocytes decreases isoproterenol-stimulated Hsp20 phosphorylation, consistent with an AC9-Hsp20 complex. Phosphorylation of Hsp20 occurs largely in ventricles and is vital for the cardioprotective effects of Hsp20. Decreased Hsp20 phosphorylation suggests a potential baseline ventricular defect for AC9−/−. Doppler echocardiography of AC9−/− displays a decrease in the early ventricular filling velocity and ventricular filling ratio (E/A), indicative of grade 1 diastolic dysfunction and emphasizing the importance of local cAMP production in the context of macromolecular complexes.
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Abstract
Cardiac arrhythmias can follow disruption of the normal cellular electrophysiological processes underlying excitable activity and their tissue propagation as coherent wavefronts from the primary sinoatrial node pacemaker, through the atria, conducting structures and ventricular myocardium. These physiological events are driven by interacting, voltage-dependent, processes of activation, inactivation, and recovery in the ion channels present in cardiomyocyte membranes. Generation and conduction of these events are further modulated by intracellular Ca2+ homeostasis, and metabolic and structural change. This review describes experimental studies on murine models for known clinical arrhythmic conditions in which these mechanisms were modified by genetic, physiological, or pharmacological manipulation. These exemplars yielded molecular, physiological, and structural phenotypes often directly translatable to their corresponding clinical conditions, which could be investigated at the molecular, cellular, tissue, organ, and whole animal levels. Arrhythmogenesis could be explored during normal pacing activity, regular stimulation, following imposed extra-stimuli, or during progressively incremented steady pacing frequencies. Arrhythmic substrate was identified with temporal and spatial functional heterogeneities predisposing to reentrant excitation phenomena. These could arise from abnormalities in cardiac pacing function, tissue electrical connectivity, and cellular excitation and recovery. Triggering events during or following recovery from action potential excitation could thereby lead to sustained arrhythmia. These surface membrane processes were modified by alterations in cellular Ca2+ homeostasis and energetics, as well as cellular and tissue structural change. Study of murine systems thus offers major insights into both our understanding of normal cardiac activity and its propagation, and their relationship to mechanisms generating clinical arrhythmias.
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Affiliation(s)
- Christopher L-H Huang
- Physiological Laboratory and the Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
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5
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Wojtovich AP, Nadtochiy SM, Urciuoli WR, Smith CO, Grunnet M, Nehrke K, Brookes PS. A non-cardiomyocyte autonomous mechanism of cardioprotection involving the SLO1 BK channel. PeerJ 2013; 1:e48. [PMID: 23638385 PMCID: PMC3628382 DOI: 10.7717/peerj.48] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Accepted: 02/19/2013] [Indexed: 12/30/2022] Open
Abstract
Opening of BK-type Ca2+ activated K+ channels protects the heart against ischemia-reperfusion (IR) injury. However, the location of BK channels responsible for cardioprotection is debated. Herein we confirmed that openers of the SLO1 BK channel, NS1619 and NS11021, were protective in a mouse perfused heart model of IR injury. As anticipated, deletion of the Slo1 gene blocked this protection. However, in an isolated cardiomyocyte model of IR injury, protection by NS1619 and NS11021 was insensitive to Slo1 deletion. These data suggest that protection in intact hearts occurs by a non-cardiomyocyte autonomous, SLO1-dependent, mechanism. In this regard, an in-situ assay of intrinsic cardiac neuronal function (tachycardic response to nicotine) revealed that NS1619 preserved cardiac neurons following IR injury. Furthermore, blockade of synaptic transmission by hexamethonium suppressed cardioprotection by NS1619 in intact hearts. These results suggest that opening SLO1 protects the heart during IR injury, via a mechanism that involves intrinsic cardiac neurons. Cardiac neuronal ion channels may be useful therapeutic targets for eliciting cardioprotection.
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Affiliation(s)
- Andrew P Wojtovich
- Department of Medicine, University of Rochester Medical Center , Rochester, NY , USA
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6
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Sissung TM, Gardner ER, Piekarz RL, Howden R, Chen X, Woo S, Franke R, Clark JA, Miller-DeGraff L, Steinberg SM, Venzon D, Liewehr D, Kleeberger SR, Bates SE, Price DK, Rosing DR, Cabell C, Sparreboom A, Figg WD. Impact of ABCB1 allelic variants on QTc interval prolongation. Clin Cancer Res 2011; 17:937-46. [PMID: 21106724 PMCID: PMC3074531 DOI: 10.1158/1078-0432.ccr-10-0925] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
PURPOSE Although the ABCB1 (P-glycoprotein) drug transporter is a constituent of several blood-tissue barriers (i.e., blood-brain and blood-nerve), its participation in a putative blood-heart barrier has been poorly explored. ABCB1 could decrease the intracardiac concentrations of drugs that cause QT prolongation and cardiotoxicity. EXPERIMENTAL DESIGN ABCB1-related romidepsin transport kinetics were explored in LLC-PK1 cells transfected with different ABCB1 genetic variants. ABCB1 plasma and intracardiac concentrations were determined in Abcb1a/1b (-/-) mice and wild-type FVB controls. These same mice were used to evaluate romidepsin-induced heart rate-corrected QT interval (QTc) prolongation over time. Finally, a cohort of 83 individuals with available QTcB and ABCB1 genotyping data were used to compare allelic variation in ABCB1 versus QTc-prolongation phenotype. RESULTS Here, we show that mice lacking the ABCB1-type P-glycoprotein have higher intracardiac concentrations of a model ABCB1 substrate, romidepsin, that correspond to changes in QT prolongation from baseline (ΔQTc) over time. Consistent with this observation, we also show that patients carrying genetic variants that could raise ABCB1 expression in the cardiac endothelium have lower ΔQTc following a single dose of romidepsin. CONCLUSIONS To our knowledge, this is the first evidence that Abcb1-type P-glycoprotein can limit intracardiac exposure to a drug that mediates QT prolongation and suggests that certain commonly inherited polymorphisms in ABCB1 may serve as markers for QT prolongation following the administration of ABCB1-substrate drugs.
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Affiliation(s)
- Tristan M. Sissung
- Clinical Pharmacology Program, Center for Cancer Research National Cancer Institute, Bethesda, MD
| | - Erin R. Gardner
- Clinical Pharmacology Program, SAIC-Frederick, NCI-Frederick, MD
| | - Richard L. Piekarz
- Medical Oncology Branch, Center for Cancer Research National Cancer Institute, Bethesda, MD
| | - Reuben Howden
- Laboratory of Respiratory Biology, National Institute of Environmental Health Science, Durham, NC
| | - Xaiohong Chen
- Clinical Pharmacology Program, Center for Cancer Research National Cancer Institute, Bethesda, MD
| | - Sukyung Woo
- Clinical Pharmacology Program, Center for Cancer Research National Cancer Institute, Bethesda, MD
| | - Ryan Franke
- Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, TN
| | - James A. Clark
- Laboratory of Respiratory Biology, National Institute of Environmental Health Science, Durham, NC
| | - Laura Miller-DeGraff
- Laboratory of Respiratory Biology, National Institute of Environmental Health Science, Durham, NC
| | - Seth M. Steinberg
- Biostatistics and Data Management Section, National Cancer Institute, Bethesda, MD
| | - David Venzon
- Biostatistics and Data Management Section, National Cancer Institute, Bethesda, MD
| | - David Liewehr
- Biostatistics and Data Management Section, National Cancer Institute, Bethesda, MD
| | - Steven R. Kleeberger
- Laboratory of Respiratory Biology, National Institute of Environmental Health Science, Durham, NC
| | - Susan E. Bates
- Medical Oncology Branch, Center for Cancer Research National Cancer Institute, Bethesda, MD
| | - Douglas K. Price
- Molecular Pharmacology Section, Center for Cancer Research National Cancer Institute, Bethesda, MD
| | - Douglas R. Rosing
- Cardiovascular Branch, National Heart Lung and Blood Institute, Bethesda, MD
| | | | - Alex Sparreboom
- Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, TN
| | - William D. Figg
- Clinical Pharmacology Program, Center for Cancer Research National Cancer Institute, Bethesda, MD
- Medical Oncology Branch, Center for Cancer Research National Cancer Institute, Bethesda, MD
- Molecular Pharmacology Section, Center for Cancer Research National Cancer Institute, Bethesda, MD
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Sabir IN, Ma N, Jones VJ, Goddard CA, Zhang Y, Kalin A, Grace AA, Huang CLH. Alternans in genetically modified langendorff-perfused murine hearts modeling catecholaminergic polymorphic ventricular tachycardia. Front Physiol 2010; 1:126. [PMID: 21423368 PMCID: PMC3059940 DOI: 10.3389/fphys.2010.00126] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2010] [Accepted: 07/29/2010] [Indexed: 11/23/2022] Open
Abstract
The relationship between alternans and arrhythmogenicity was studied in genetically modified murine hearts modeling catecholaminergic polymorphic ventricular tachycardia (CPVT) during Langendorff perfusion, before and after treatment with catecholamines and a β-adrenergic antagonist. Heterozygous (RyR2p/s) and homozygous (RyR2s/s) RyR2-P2328S hearts, and wild-type (WT) controls, were studied before and after treatment with epinephrine (100 nM and 1 μM) and propranolol (100 nM). Monophasic action potential recordings demonstrated significantly greater incidences of arrhythmia in RyR2p/s and RyR2s/s hearts as compared to WTs. Arrhythmogenicity in RyR2s/s hearts was associated with alternans, particularly at short baseline cycle lengths. Both phenomena were significantly accentuated by treatment with epinephrine and significantly diminished by treatment with propranolol, in full agreement with clinical expectations. These changes took place, however, despite an absence of changes in mean action potential durations, ventricular effective refractory periods or restitution curve characteristics. Furthermore pooled data from all hearts in which arrhythmia occurred demonstrated significantly greater alternans magnitudes, but similar restitution curve slopes, to hearts that did not demonstrate arrhythmia. These findings thus further validate the RyR2-P2328S murine heart as a model for human CPVT, confirming an alternans phenotype in common with murine genetic models of the Brugada syndrome and the congenital long-QT syndrome type 3. In contrast to these latter similarities, however, this report demonstrates the dissociation of alternans from changes in the properties of restitution curves for the first time in a murine model of a human arrhythmic syndrome.
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Affiliation(s)
- Ian N Sabir
- Physiological Laboratory, Department of Physiology, Development and Neuroscience, University of Cambridge Cambridge, UK.
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Perrin-Terrin A, Pathak A, Lapeyre-Mestre M. QT interval prolongation: prevalence, risk factors and pharmacovigilance data among methadone-treated patients in France. Fundam Clin Pharmacol 2010; 25:503-10. [PMID: 20825488 DOI: 10.1111/j.1472-8206.2010.00871.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Several reports have suggested the role of methadone in QT prolongation, Torsades de Pointes (TdP), and ventricular arrhythmia. The aim of this study was to identify the frequency of QT interval prolongation and QT dispersion among a population of addict patients treated with methadone, completed by the description of cardiac events reported to the French pharmacovigilance system. QT interval (corrected with the Bazett's method) and dispersion were measured on a cohort of patients treated with methadone during their visit to addiction specialized centers in Southwest of France. Whenever possible, methadone blood concentrations were measured. In addition, reports concerning methadone were searched in the French Pharmacovigilance database from 1996 to 2007. The cohort included 42 patients with mean QTc length of 414.3 ± 28.5 ms and mean QT dispersion of 66.0 ± 41.1 ms. None of the patient presented a QTc above 500 ms. These values were higher in patients with recent increase in methadone dose, use of tobacco or drugs prolonging QT, and history of cardiac disease. We found five cases of QT prolongation (3 TdP) and seven cases of sudden deaths in the French pharmacovigilance database (2.2% of methadone reports). Most of these events occurred after introducing methadone or another drug potentially interacting with methadone. Methadone can prolong the QT interval at dose usually used for addiction maintenance treatment in France. A cardiac evaluation, with at least a systematic ECG, could be useful during methadone treatment, particularly in case of recent modification of the regimen.
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Affiliation(s)
- Aurélie Perrin-Terrin
- Unité de Pharmacoépidémiologie EA3696, Inserm, U558, Faculté de Médecine Purpan, Université de Toulouse, UPS, 37 Allées Jules Guesde; F-31000 Toulouse, France
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9
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Feng Y, Caiping M, Li C, Can R, Feichao X, Li Z, Zhice X. Fetal and offspring arrhythmia following exposure to nicotine during pregnancy. J Appl Toxicol 2010; 30:53-8. [PMID: 19728315 DOI: 10.1002/jat.1471] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Although recent studies have demonstrated prenatal nicotine can increase cardiovascular risk in the offspring, it is unknown whether exposure to nicotine during pregnancy also may be a risk for development of arrhythmia in the offspring. In addition, in previous studies of fetal arrhythmia affected by smoking, only two patterns, bradycardia and tachycardia, were observed. The present study examined acute effects of maternal nicotine on the fetal arrhythmia in utero, and chronic influence on offspring arrhythmia at adult stage following prenatal exposure to nicotine. Nicotine was administered to pregnant ewes and rats. In the fetal sheep, intravenous nicotine not only induced changes of fetal heart rate, but also caused cardiac cycle irregularity, single and multiple dropped cardiac cycles. Although maternal nicotine had no influence on fetal blood pH, lactic acid, hemocrit, Na(+), K(+) levels and plasma osmolality, fetal blood PO(2) levels were significantly decreased following maternal nicotine in ewes. In offspring rats at 4-5 months after birth, prenatal exposure to nicotine significantly increased heart rate and premature ventricular contraction in restraint stress. In addition, arrhythmias induced by injection of nicotine were higher in the offspring prenatal exposure to nicotine in utero. The results provide new evidence that exposure to nicotine in pregnancy can cause fetal arrhythmia in various patterns besides tachycardia and bradycardia, the possible mechanisms for nicotine-induced fetal arrhythmia included in utero hypoxia. Importantly, following exposure to nicotine significantly increased risk of arrhythmia in the adult offspring. The finding offers new insight for development of cardiac rhythm problems in fetal origins.
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Affiliation(s)
- Yu Feng
- Perinatal Biology Center, Soochow University, Suzhou 213325, China
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10
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Mansén A, Tiselius C, Sand P, Fauconnier J, Westerblad H, Rydqvist B, Vennström B. Thyroid hormone receptor alpha can control action potential duration in mouse ventricular myocytes through the KCNE1 ion channel subunit. Acta Physiol (Oxf) 2010; 198:133-42. [PMID: 19832729 DOI: 10.1111/j.1748-1716.2009.02052.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AIMS The reduced heart rate and prolonged QT(end) duration in mice deficient in thyroid hormone receptor (TR) alpha1 may involve aberrant expression of the K(+) channel alpha-subunit KCNQ1 and its regulatory beta-subunit KCNE1. Here we focus on KCNE1 and study whether increased KCNE1 expression can explain changes in cardiac function observed in TRalpha1-deficient mice. METHODS TR-deficient, KCNE1-overexpressing and their respective wildtype (wt) mice were used. mRNA and protein expression were assessed with Northern and Western blot respectively. Telemetry was used to record electrocardiogram and temperature in freely moving mice. Patch-clamp was used to measure action potentials (APs) in isolated cardiomyocytes and ion currents in Chinese hamster ovary (CHO) cells. RESULTS KCNE1 was four to 10-fold overexpressed in mice deficient in TRalpha1. Overexpression of KCNE1 with a heart-specific promoter in transgenic mice resulted in a cardiac phenotype similar to that in TRalpha1-deficient mice, including a lower heart rate and prolonged QT(end) time. Cardiomyocytes from KCNE1-overexpressing mice displayed increased AP duration. CHO cells transfected with expression plasmids for KCNQ1 and KCNE1 showed an outward rectifying current that was maximal at equimolar plasmids for KCNQ1-KCNE1 and decreased at higher KCNE1 levels. CONCLUSION The bradycardia and prolonged QT(end) time in hypothyroid states can be explained by altered K(+) channel function due to decreased TRalpha1-dependent repression of KCNE1 expression.
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Affiliation(s)
- A Mansén
- Department of Cell and Molecular Biology, Karolinska Institute, Stockholm, Sweden
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Batchu SN, Law E, Brocks DR, Falck JR, Seubert JM. Epoxyeicosatrienoic acid prevents postischemic electrocardiogram abnormalities in an isolated heart model. J Mol Cell Cardiol 2008; 46:67-74. [PMID: 18973759 DOI: 10.1016/j.yjmcc.2008.09.711] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2008] [Revised: 09/22/2008] [Accepted: 09/26/2008] [Indexed: 10/21/2022]
Abstract
Cytochrome P450 epoxygenases metabolize arachidonic acid (AA) to epoxyeicosatrienoic acids (EETs) which are in turn converted to dihydroxyeicosatrienoic acids (DHETs) by soluble epoxide hydrolase (sEH). The main objective of this study was to investigate the protective effects of EETs following ischemic injury using an ex vivo electrocardiogram (EKG) model. Hearts from C57Bl/6, transgenic mice with cardiomyocyte-specific overexpression of CYP2J2 (Tr) and wildtype (WT) littermates were excised and perfused with constant pressure in a Langendorff apparatus. Electrodes were placed superficially at the right atrium and left ventricle to assess EKG waveforms. In ischemic reperfusion experiments hearts were subjected to 20 min of global no-flow ischemia followed by 20 min of reperfusion (R20). The EKG from C57Bl/6 hearts perfused with 1 microM 14,15-EET showed less QT prolongation (QTc) and ST elevation (STE) (QTc=41+/-3, STE=2.3+/-0.3; R20: QTc=42+/-2 ms, STE=1.2+/-0.2mv) than control hearts (QTc=36+/-2, STE=2.3+/-0.2; R20: QTc=53+/-3 ms; STE=3.6+/-0.4mv). Similar results of reduced QT prolongation and ST elevation were observed in EKG recording from CYP2J2 Tr mice (QTc=35+/-1, STE=1.9+/-0.1; R20: QTc=38+/-4 ms, STE=1.3+/-0.2mv) compared to WT hearts. The putative epoxygenase inhibitor MS-PPOH (50 microM) and EET antagonist 14,15-EEZE (10 microM) both abolished the cardioprotective response, implicating EETs in this process. In addition, separate exposure to the K(ATP) channel blockers glibenclamide (1 microM) and HMR1098 (10 microM), or the PKA protein inhibitor H89 (50 nM) during reperfusion abolished the improved repolarization in both the models. Consistent with a role of PKA, CYP2J2 Tr mice had an enhanced activation of the PKAalpha regulatory II subunit in plasma membrane following IR injury. The present data demonstrate that EETs can enhance the recovery of ventricular repolarization following ischemia, potentially by facilitating activation of K(+) channels and PKA-dependent signaling.
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Affiliation(s)
- S N Batchu
- Faculty of Pharmacy and Pharmaceutical Sciences, 3126 Dentistry/Pharmacy Centre, University of Alberta, Edmonton, AB, Canada
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12
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Sabir IN, Killeen MJ, Grace AA, Huang CLH. Ventricular arrhythmogenesis: Insights from murine models. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2008; 98:208-18. [DOI: 10.1016/j.pbiomolbio.2008.10.011] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Abstract
Sudden cardiac death stemming from ventricular arrhythmogenesis is one of the major causes of mortality in the developed world. Congenital and acquired forms of long QT syndrome (LQTS) are in turn associated with life threatening arrhythmias. Over the past decade our understanding of arrhythmogenic mechanisms in the setting of these diseases has increased greatly due to the creation of a number of animal models. Of these, the genetically amenable mouse has proved to be a particularly powerful tool. This review summarizes the congenital and acquired LQTS and describes the various mouse models that have been created to further probe arrhythmogenic mechanisms.
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Affiliation(s)
- M J Killeen
- Physiological Laboratory, University of Cambridge, Cambridge, UK.
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14
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Knollmann BC, Sirenko S, Rong Q, Katchman AN, Casimiro M, Pfeifer K, Ebert SN. Kcnq1 contributes to an adrenergic-sensitive steady-state K+ current in mouse heart. Biochem Biophys Res Commun 2007; 360:212-8. [PMID: 17597584 PMCID: PMC2025686 DOI: 10.1016/j.bbrc.2007.06.038] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2007] [Accepted: 06/07/2007] [Indexed: 10/23/2022]
Abstract
It has been suggested that Kcne1 subunits are required for adrenergic regulation of Kcnq1 potassium channels. However, in adult mouse hearts, which do not express Kcne1, loss of Kcnq1 causes a Long QT phenotype during adrenergic challenge, raising the possibility that native Kcnq1 currents exist and are adrenergically regulated even in absence of Kcne1. Here, we used immunoblotting and immunohistochemical staining to show that Kcnq1 protein is present in adult mouse hearts. Voltage-clamp experiments demonstrated that Kcnq1 contributes to a steady-state outward current (I(SS)) in wild-type (Kcnq1(+/+)) ventricular myocytes during isoproterenol stimulation, resulting in a significant 7.1% increase in I(SS) density (0.43+/-0.16 pA/pF, p <0.05, n =15), an effect that was absent in Kcnq1-deficient (Kcnq1(-/-)) myocytes (-0.14+/-0.13 pA/pF, n =17). These results demonstrate for the first time that Kcnq1 protein is expressed in adult mouse hearts where it contributes to a beta-adrenergic-induced component of I(SS) that does not require co-assembly with Kcne1.
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Affiliation(s)
- Bjorn C Knollmann
- Department of Pharmacology, Georgetown University Medical Center, Washington, DC, USA
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15
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Suto F, Zhu W, Chan A, Gross GJ. IKr and IKs remodeling differentially affects QT interval prolongation and dynamic adaptation to heart rate acceleration in bradycardic rabbits. Am J Physiol Heart Circ Physiol 2007; 292:H1782-8. [PMID: 17142341 DOI: 10.1152/ajpheart.00932.2006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Bradycardic ventricular electrical remodeling predisposes to lethal tachyarrhythmias. We investigated the early temporal sequence and reversibility of electrical remodeling in a rabbit complete heart block model subjected to bradycardic ventricular pacing for either 2 or 8 days, with a third group of animals undergoing 8 days of bradycardic pacing followed by 8 days of physiological-rate pacing. At specified time points after complete heart block induction and pacing initiation, steady-state QT interval measurements and variability as well as dynamic QT interval adaptation to abrupt heart rate acceleration were assessed in the absence and presence of isoproterenol. Rapidly ( IKr) and slowly ( IKs) activating delayed rectifier repolarizing K+ tail current densities were evaluated using whole cell patch clamp in isolated right ventricular myocytes. Steady-state QT interval prolongation at both 2 and 8 days was associated with moderate IKr reduction. IKs downregulation was apparent by day 2 but more profound at day 8. Dynamic QT interval adaptation was impaired under baseline conditions at day 8 but only during isoproterenol administration at day 2. Both in vivo and cellular manifestations of remodeling reverted toward control values after 8 days of physiological-rate pacing. In conclusion, in this bradycardic model, IKs downregulation 1) proceeds more gradually but more extensively than that of IKr and 2) is most prominently associated with impaired dynamic QT interval adaptation to heart rate acceleration. Isoproterenol blunts the dynamic QT interval response in animals with partially downregulated IKs, consistent with stress-related phenomena in known IKs-impaired states. Relative early sparing of IKs could explain the delay in the onset of lethal tachyarrhythmia predisposition in bradycardic electrical remodeling. Reversibility of remodeling supports the potential utility of preventive pacing intervention soon after bradycardia onset.
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Affiliation(s)
- Fumiaki Suto
- Physiology and Experimental Medicine Program, Hospital for Sick Children Research Institute, University of Toronto, Toronto, Canada
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16
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Thomas G, Killeen MJ, Gurung IS, Hakim P, Balasubramaniam R, Goddard CA, Grace AA, Huang CLH. Mechanisms of ventricular arrhythmogenesis in mice following targeted disruption of KCNE1 modelling long QT syndrome 5. J Physiol 2006; 578:99-114. [PMID: 17095567 PMCID: PMC2075126 DOI: 10.1113/jphysiol.2006.118133] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Mutations within KCNE1 encoding a transmembrane protein which coassembles with K+ channels mediating slow K+, I(Ks), currents are implicated in cardiac action potential prolongation and ventricular arrhythmogenicity in long QT syndrome 5. We demonstrate the following potentially arrhythmogenic features in simultaneously recorded, left ventricular, endocardial and epicardial monophasic action potentials from Langendorff-perfused murine KCNE1-/- hearts for the first time. (1) Prolonged epicardial (57.1 +/- 0.5 ms cf. 36.1 +/- 0.07 ms in wild-type (WT), P < 0.001; n = 5) and endocardial action potential duration at 90% repolarication (APD90) (54.4 +/- 2.4 ms cf. 48.5 +/- 0.3 ms, P < 0.05; n = 5). (2) Negative transmural repolarization gradients (DeltaAPD90: endocardial minus epicardial APD90) (-2.5 +/- 2.4 ms, compared with 12.4 +/- 1.1 ms in WT, P < 0.001; n = 5). (3) Frequent epicardial early afterdepolarizations (EADs) and spontaneous ventricular tachycardia (VT) in 4 out of 5 KCNE1-/- hearts but not WT (n = 5). EADs were especially frequent following temporary cessations of ventricular pacing. (4) Monomorphic VT lasting 1.36 +/- 0.2 s in 5 out of 5 KCNE1-/- hearts, following premature stimuli but not WT (n = 5). (5) Epicardial APD alternans. Perfusion of KCNE1-/- hearts with 1 mum nifedipine induced potentially anti-arrhythmic changes including: (1) restored epicardial APD90 (from 57.1 +/- 0.5 ms to 42.3 +/- 0.4 ms, P < 0.001; n = 5); (2) altered DeltaAPD90 to values (11.2 +/- 2.6) close to WT (P > 0.05; n = 5); (3) EAD suppression during both spontaneous activity and following cessation of ventricular pacing (n = 5) to give similar features to WT controls (n = 5); (4) suppression of programmed electrical stimulation-induced VT; and (5) suppression of APD alternans. These findings suggest arrhythmic effects of reduced outward currents expected in KCNE1-/- hearts and their abolition by antagonism of inward L-type Ca2+ current.
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Affiliation(s)
- Glyn Thomas
- Section of Cardiovascular Biology, Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, UK
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17
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Gohma H, Kuramoto T, Kuwamura M, Okajima R, Tanimoto N, Yamasaki KI, Nakanishi S, Kitada K, Makiyama T, Akao M, Kita T, Sasa M, Serikawa T. WTC deafness Kyoto (dfk): a rat model for extensive investigations ofKcnq1functions. Physiol Genomics 2006; 24:198-206. [PMID: 16368876 DOI: 10.1152/physiolgenomics.00221.2005] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
KCNQ1 forms K+channels by assembly with regulatory subunit KCNE proteins and plays a key role in the K+homeostasis in a variety of tissues. In the heart, KCNQ1 is coassembled with KCNE1 to produce a cardiac delayed rectifier K+current. In the inner ear, the KCNQ1/KCNE1 complex maintains the high concentration of K+in the endolymph. In the stomach, KCNQ1 is coassembled with KCNE2 to form the K+exflux channel that is essential for gastric acid secretion. In the colon and small intestine, KCNQ1 is coassembled with KCNE3 to play an important role in transepithelial cAMP-stimulated Cl−secretion. For further understanding of Kcnq1 function in vivo, an animal model has been required. Here we reported the identification of a coisogenic Kcnq1 mutant rat, named deafness Kyoto ( dfk), and the characterization of its phenotypes. WTC- dfk rats carried intragenic deletion at the Kcnq1 gene and showed impaired gain of weight, deafness, and imbalance resulting from the marked reduction of endolymph, prolonged QT interval in the electrocardiogram (ECG), and gastric achlorhydria associated with hypertrophic gastric mucosa. Surprisingly, WTC- dfk rats showed hypertension, which suggested that Kcnq1 might be involved in the regulation of blood pressure. These findings suggest that WTC- dfk rats could represent a powerful tool for studying the physiological functions of KCNQ1 and for the establishment of new therapeutic procedures for Kcnq1-related diseases.
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Affiliation(s)
- Hiroshi Gohma
- Institute of Laboratory Animals, Graduate School of Medicine, Kyoto University, Kyoto, Japan
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18
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Casimiro MC, Knollmann BC, Yamoah EN, Nie L, Vary JC, Sirenko SG, Greene AE, Grinberg A, Huang SP, Ebert SN, Pfeifer K. Targeted point mutagenesis of mouse Kcnq1: phenotypic analysis of mice with point mutations that cause Romano-Ward syndrome in humans. Genomics 2005; 84:555-64. [PMID: 15498462 DOI: 10.1016/j.ygeno.2004.06.007] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2004] [Revised: 06/08/2004] [Accepted: 06/09/2004] [Indexed: 01/23/2023]
Abstract
Inherited long QT syndrome is most frequently associated with mutations in KCNQ1, which encodes the primary subunit of a potassium channel. Patients with mutations in KCNQ1 may show only the cardiac defect (Romano-Ward syndrome or RWS) or may also have severe deafness (Jervell and Lange-Nielsen syndrome or JLNS). Targeted disruption of mouse Kcnq1 models JLNS in that mice are deaf and show abnormal ECGs. However, the phenotype is broader than that seen in patients. Most dramatically, the inner ear defects result in a severe hyperactivity/circling behavior, which may influence cardiac function. To understand the etiology of the cardiac phenotype in these mice and to generate a potentially more useful model system, we generated new mouse lines by introducing point mutations associated with RWS. The A340E line phenocopies RWS: the repolarization phenotype is inherited in a dominant manner and is observed independent of any inner ear defect. The T311I line phenocopies JLNS, with deafness associated with inner hair cell malfunction.
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Affiliation(s)
- Mathew C Casimiro
- Laboratory of Mammalian Genes and Development, NICHD/National Institutes of Health, Building 6B Room 2B-206, Bethesda, MD 20892, USA
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19
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Rasmussen HB, Møller M, Knaus HG, Jensen BS, Olesen SP, Jørgensen NK. Subcellular localization of the delayed rectifier K+channels KCNQ1 and ERG1 in the rat heart. Am J Physiol Heart Circ Physiol 2004; 286:H1300-9. [PMID: 14670813 DOI: 10.1152/ajpheart.00344.2003] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In the heart, several K+channels are responsible for the repolarization of the cardiac action potential, including transient outward and delayed rectifier K+currents. In the present study, the cellular and subcellular localization of the two delayed rectifier K+channels, KCNQ1 and ether- a- go- go-related gene-1 (ERG1), was investigated in the adult rat heart. Confocal immunofluorescence microscopy of atrial and ventricular cells revealed that whereas KCNQ1 labeling was detected in both the peripheral sarcolemma and a structure transversing the myocytes, ERG1 immunoreactivity was confined to the latter. Immunoelectron microscopy of atrial and ventricular myocytes showed that the ERG1 channel was primarily expressed in the transverse tubular system and its entrance, whereas KCNQ1 was detected in both the peripheral sarcolemma and in the T tubules. Thus, whereas ERG1 displays a very restricted subcellular localization pattern, KCNQ1 is more widely distributed within the cardiac cells. The localization of these K+channels to the transverse tubular system close to the Ca2+channels renders them with maximal repolarizing effect.
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Affiliation(s)
- Hanne Borger Rasmussen
- Department of Medical Physiology and Copenhagen Heart Research, University of Copenhagen, The Panum Institute, DK-2200 Copenhagen N, Denmark.
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20
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Knollmann BC, Casimiro MC, Katchman AN, Sirenko SG, Schober T, Rong Q, Pfeifer K, Ebert SN. Isoproterenol Exacerbates a Long QT Phenotype in Kcnq1-Deficient Neonatal Mice: Possible Roles for Human-Like Kcnq1 Isoform 1 and Slow Delayed Rectifier K+ Current. J Pharmacol Exp Ther 2004; 310:311-8. [PMID: 15004216 DOI: 10.1124/jpet.103.063743] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To determine whether the neonatal mouse can serve as a useful model for studying the molecular pharmacological basis of Long QT Syndrome Type 1 (LQT1), which has been linked to mutations in the human KCNQ1 gene, we measured QT intervals from electrocardiogram (ECG) recordings of wild-type (WT) and Kcnq1 knockout (KO) neonates before and after injection with the beta-adrenergic receptor agonist, isoproterenol (0.17 mg/kg, i.p.). Modest but significant increases in JT, QT, and rate-corrected QT (QTc) intervals were found in KO neonates relative to WT siblings during baseline ECG assessments (QTc = 57 +/- 3 ms, n = 22 versus 49 +/- 2 ms, n = 28, respectively, p < 0.05). Moreover, JT, QT, and QTc intervals significantly increased following isoproterenol challenge in the KO (p < 0.01) but not the WT group (p = 0.57). Furthermore, whole-cell patch-clamp recordings show that the slow delayed rectifier K+ current (IKs) was absent in KO but present in WT myocytes, where it was strongly enhanced by isoproterenol. This finding was confirmed by showing that the selective IKs inhibitor, L-735,821, blocked IKs and prolonged action potential duration in WT but not KO hearts. These data demonstrate that disruption of the Kcnq1 gene leads to loss of IKs, resulting in a long QT phenotype that is exacerbated by beta-adrenergic stimulation. This phenotype closely reflects that observed in human LQT1 patients, suggesting that the neonatal mouse serves as a valid model for this condition. This idea is further supported by new RNA data showing that there is a high degree of homology (>88% amino acid identity) between the predominant human and mouse cardiac Kcnq1 isoforms.
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Affiliation(s)
- Bjorn C Knollmann
- Department of Pharmacology, Georgetown University Medical Center, Washington, DC 20007, USA
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