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Wang Y, Li Q, Tao B, Angelini M, Ramadoss S, Sun B, Wang P, Krokhaleva Y, Ma F, Gu Y, Espinoza A, Yamauchi K, Pellegrini M, Novitch B, Olcese R, Qu Z, Song Z, Deb A. Fibroblasts in heart scar tissue directly regulate cardiac excitability and arrhythmogenesis. Science 2023; 381:1480-1487. [PMID: 37769108 PMCID: PMC10768850 DOI: 10.1126/science.adh9925] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Accepted: 08/11/2023] [Indexed: 09/30/2023]
Abstract
After heart injury, dead heart muscle is replaced by scar tissue. Fibroblasts can electrically couple with myocytes, and changes in fibroblast membrane potential can lead to myocyte excitability, which suggests that fibroblast-myocyte coupling in scar tissue may be responsible for arrhythmogenesis. However, the physiologic relevance of electrical coupling of myocytes and fibroblasts and its impact on cardiac excitability in vivo have never been demonstrated. We genetically engineered a mouse that expresses the optogenetic cationic channel ChR2 (H134R) exclusively in cardiac fibroblasts. After myocardial infarction, optical stimulation of scar tissue elicited organ-wide cardiac excitation and induced arrhythmias in these animals. Complementing computational modeling with experimental approaches, we showed that gap junctional and ephaptic coupling, in a synergistic yet functionally redundant manner, excited myocytes coupled to fibroblasts.
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Affiliation(s)
- Yijie Wang
- Division of Cardiology, Department of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
- Cardiovascular Theme, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
- Department of Molecular, Cell and Developmental Biology, University of California Los Angeles, Los Angeles, CA 90095, USA
- Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California Los Angeles, Los Angeles, CA 90095, USA
- Molecular Biology Institute, University of California Los Angeles, Los Angeles, CA 90095, USA
- California Nanosystems Institute, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Qihao Li
- Peng Cheng Laboratory, Shenzhen, Guangdong 518000, China
| | - Bo Tao
- Division of Cardiology, Department of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
- Cardiovascular Theme, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
- Department of Molecular, Cell and Developmental Biology, University of California Los Angeles, Los Angeles, CA 90095, USA
- Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California Los Angeles, Los Angeles, CA 90095, USA
- Molecular Biology Institute, University of California Los Angeles, Los Angeles, CA 90095, USA
- California Nanosystems Institute, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Marina Angelini
- Department of Anesthesiology and Perioperative Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Sivakumar Ramadoss
- Division of Cardiology, Department of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
- Cardiovascular Theme, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
- Department of Molecular, Cell and Developmental Biology, University of California Los Angeles, Los Angeles, CA 90095, USA
- Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California Los Angeles, Los Angeles, CA 90095, USA
- Molecular Biology Institute, University of California Los Angeles, Los Angeles, CA 90095, USA
- California Nanosystems Institute, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Baiming Sun
- Division of Cardiology, Department of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
- Cardiovascular Theme, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
- Department of Molecular, Cell and Developmental Biology, University of California Los Angeles, Los Angeles, CA 90095, USA
- Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California Los Angeles, Los Angeles, CA 90095, USA
- Molecular Biology Institute, University of California Los Angeles, Los Angeles, CA 90095, USA
- California Nanosystems Institute, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Ping Wang
- Division of Cardiology, Department of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
- Cardiovascular Theme, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
- Department of Molecular, Cell and Developmental Biology, University of California Los Angeles, Los Angeles, CA 90095, USA
- Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California Los Angeles, Los Angeles, CA 90095, USA
- Molecular Biology Institute, University of California Los Angeles, Los Angeles, CA 90095, USA
- California Nanosystems Institute, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Yuliya Krokhaleva
- UCLA Cardiac Arrhythmia Center, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Feiyang Ma
- Department of Cell and Developmental Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Yiqian Gu
- Department of Molecular, Cell and Developmental Biology, University of California Los Angeles, Los Angeles, CA 90095, USA
- Institute for Quantitative and Computational Biosciences–The Collaboratory, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Alejandro Espinoza
- Department of Molecular, Cell and Developmental Biology, University of California Los Angeles, Los Angeles, CA 90095, USA
- Institute for Quantitative and Computational Biosciences–The Collaboratory, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Ken Yamauchi
- Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California Los Angeles, Los Angeles, CA 90095, USA
- Department of Neurobiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Matteo Pellegrini
- Department of Molecular, Cell and Developmental Biology, University of California Los Angeles, Los Angeles, CA 90095, USA
- Institute for Quantitative and Computational Biosciences–The Collaboratory, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Bennett Novitch
- Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California Los Angeles, Los Angeles, CA 90095, USA
- Department of Neurobiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Riccardo Olcese
- Department of Anesthesiology and Perioperative Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
- Department of Physiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Zhilin Qu
- Division of Cardiology, Department of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Zhen Song
- Peng Cheng Laboratory, Shenzhen, Guangdong 518000, China
| | - Arjun Deb
- Division of Cardiology, Department of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
- Cardiovascular Theme, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
- Department of Molecular, Cell and Developmental Biology, University of California Los Angeles, Los Angeles, CA 90095, USA
- Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California Los Angeles, Los Angeles, CA 90095, USA
- Molecular Biology Institute, University of California Los Angeles, Los Angeles, CA 90095, USA
- California Nanosystems Institute, University of California Los Angeles, Los Angeles, CA 90095, USA
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Zhu X, Chen R, Zhang Y, Hu J, Jiang Y, Huang K, Wang J, Li W, Shi B, Chen Y, Li L, Li B, Cheng X, Yu B, Wang Y, Kan H. Low ambient temperature increases the risk and burden of atrial fibrillation episodes: A nationwide case-crossover study in 322 Chinese cities. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 880:163351. [PMID: 37030388 DOI: 10.1016/j.scitotenv.2023.163351] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Revised: 03/23/2023] [Accepted: 04/03/2023] [Indexed: 05/27/2023]
Abstract
BACKGROUND Non-optimum ambient temperature has recently been acknowledged as an independent risk factor for disease burden, but its impact on atrial fibrillation (AF) episodes was rarely evaluated. OBJECTIVES To examine the associations between ambient non-optimum temperature and symptom onset of AF episodes and calculate the corresponding disease burden. METHODS We conducted an individual-level, time-stratified, case-crossover analysis based on a nationwide registry, which comprises of 94,711 eligible AF patients from 1993 hospitals in 322 Chinese cities from January 2015 to December 2021. Multiple moving 24 h average temperatures prior to the symptom onset of AF episodes were calculated as lag days. The associations were analyzed using conditional logistic regression combined with distributed lag non-linear models with a duration of lag 0-7 days, after controlling for criteria air pollutants. Stratification analyses were performed to explore possible effect modifiers. RESULTS There was a monotonically increasing relationship of AF onset risk with decreasing temperature. The excess AF risk occurred at lag 1 d and lasted for 5 days. Nationally, the cumulative relative risk of AF episode onset associated with extremely low temperature (-9.3 °C) over lag 0-7 d was 1.25 (95 % confidence interval: 1.08, 1.45), compared with the reference temperature (31.5 °C). The exposure-response curve was steeper in the south than in the north where there was levelling-off at lower temperature. Nationally, 7.59 % of acute AF episodes could be attributable to non-optimum temperatures. The attributable fraction was larger for southern residents, males and patients <65 years. CONCLUSION This nationwide study provides novel and robust evidence that declining ambient temperature could increase the risk of AF episode onset. We also provide the first-hand evidence that a considerable proportion of acute AF episodes could be attributable to non-optimum temperatures.
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Affiliation(s)
- Xinlei Zhu
- School of Public Health, Key Lab of Public Health Safety of the Ministry of Education, NHC Key Lab of Health Technology Assessment, Fudan University, Shanghai, China
| | - Renjie Chen
- School of Public Health, Key Lab of Public Health Safety of the Ministry of Education, NHC Key Lab of Health Technology Assessment, Fudan University, Shanghai, China
| | - Yong Zhang
- Department of Emergency, Wuhan Asia General Hospital, Wuhan, China
| | - Jialu Hu
- Department of Cardiology, Zhongshan Hospital, Fudan University, Shanghai Institute of Cardiovascular Diseases, National Clinical Research Center for Interventional Medicine, Shanghai, China
| | - Yixuan Jiang
- School of Public Health, Key Lab of Public Health Safety of the Ministry of Education, NHC Key Lab of Health Technology Assessment, Fudan University, Shanghai, China
| | - Kai Huang
- Department of Cardiology, Institute of Cardiovascular Disease, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jianan Wang
- Department of Cardiology, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Wei Li
- Department of Cardiology, the Affiliated Hospital of Guizhou Medical University, Guiyang, China
| | - Bei Shi
- Department of Cardiology, Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Yundai Chen
- Senior Department of Cardiology, the Sixth Medical Center of PLA General Hospital, Beijing, China
| | - Lang Li
- Department of Cardiology, the First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Bao Li
- Department of Cardiology, the Second Hospital of Shanxi Medical University, Taiyuan, China
| | - Xiaoshu Cheng
- Department of Cardiology, the Second Affiliated Hospital of Nanchang University, Jiangxi, China
| | - Bo Yu
- Department of Cardiology, The 2nd Affiliated Hospital of Harbin Medical University, Harbin, China.
| | - Yan Wang
- Department of Cardiology, Xiamen Cardiovascular Hospital Xiamen University, Xiamen, China.
| | - Haidong Kan
- School of Public Health, Key Lab of Public Health Safety of the Ministry of Education, NHC Key Lab of Health Technology Assessment, Fudan University, Shanghai, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, China.
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Stewart L, Turner NA. Channelling the Force to Reprogram the Matrix: Mechanosensitive Ion Channels in Cardiac Fibroblasts. Cells 2021; 10:990. [PMID: 33922466 PMCID: PMC8145896 DOI: 10.3390/cells10050990] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 04/13/2021] [Accepted: 04/21/2021] [Indexed: 02/06/2023] Open
Abstract
Cardiac fibroblasts (CF) play a pivotal role in preserving myocardial function and integrity of the heart tissue after injury, but also contribute to future susceptibility to heart failure. CF sense changes to the cardiac environment through chemical and mechanical cues that trigger changes in cellular function. In recent years, mechanosensitive ion channels have been implicated as key modulators of a range of CF functions that are important to fibrotic cardiac remodelling, including cell proliferation, myofibroblast differentiation, extracellular matrix turnover and paracrine signalling. To date, seven mechanosensitive ion channels are known to be functional in CF: the cation non-selective channels TRPC6, TRPM7, TRPV1, TRPV4 and Piezo1, and the potassium-selective channels TREK-1 and KATP. This review will outline current knowledge of these mechanosensitive ion channels in CF, discuss evidence of the mechanosensitivity of each channel, and detail the role that each channel plays in cardiac remodelling. By better understanding the role of mechanosensitive ion channels in CF, it is hoped that therapies may be developed for reducing pathological cardiac remodelling.
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Affiliation(s)
| | - Neil A. Turner
- Discovery and Translational Science Department, Leeds Institute of Cardiovascular and Metabolic Medicine, School of Medicine, University of Leeds, Leeds LS2 9JT, UK;
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Lee HH, Pan SC, Chen BY, Lo SH, Guo YL. Atrial fibrillation hospitalization is associated with exposure to fine particulate air pollutants. Environ Health 2019; 18:117. [PMID: 31888649 PMCID: PMC6937716 DOI: 10.1186/s12940-019-0554-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2019] [Accepted: 12/18/2019] [Indexed: 05/22/2023]
Abstract
BACKGROUND Although air pollutants have been associated with cardiopulmonary mortality, their effects on the occurrence of atrial fibrillation (Afib) remain unclear. This study examined the association between ambient air pollutants and Afib occurrence. METHODS Using a representative sample from the National Health Insurance Database of Taiwan, we applied a case-crossover study design to explore the associations between air pollutants and patients hospitalized with Afib from 2006 to 2011. The event day was when a patient was hospitalized with Afib, and the control days were the same days of the following weeks of the same month. The association between Afib occurrence and levels of ambient air pollutants (including particulate matter [PM] 2.5 PM10, NO2, SO2, and O3) was examined after adjusting for temperature and relative humidity. A two-pollutant model was used to examine the effect of the second pollutant when the first pollutant was determined to be significantly related to Afib. RESULTS During 2006-2011, 670 patients hospitalized with the first onset of Afib were identified. The occurrence of Afib was associated with PM2.5, in which a 22% (95% confidence interval = 3-44%) increase was related to an interquartile range increase (26.2 μg/m3) on the same day and a 19% (95% confidence interval = 0-40%) increase on the second day. A two-pollutant model was applied, and the results indicated that the effect of PM2.5 was significantly associated with the occurrence of Afib. Patients aged over 65 years with DM and with hyperlipidemia were more susceptible to the effect of PM2.5. CONCLUSIONS In conclusion, the occurrence of Afib was associated with short-term exposure to fine particulate air pollutants in the general population.
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Affiliation(s)
- Hsiu Hao Lee
- Department of Internal Medicine, Taipei City Hospital, Zhongxing Branch, No. 145, Zhengzhou Rd., Datong Dist, Taipei City, 10341, Taiwan
| | - Shih Chun Pan
- Institution of Occupational Medicine and Industrial Hygiene, National Taiwan University College of Public Health, Room 703, No. 17, Xu-Zhou Road, Taipei, 100, Taiwan
| | - Bing Yu Chen
- National Institute of Environmental Health Sciences, National Health Research Institutes, 10 F, Bldg F, 3 Yuanqu Street, Taipei, 11503, Taiwan
| | - Shih Hsiang Lo
- Department of Internal Medicine, Taipei City Hospital, Zhongxing Branch, No. 145, Zhengzhou Rd., Datong Dist, Taipei City, 10341, Taiwan
| | - Yue Leon Guo
- Institution of Occupational Medicine and Industrial Hygiene, National Taiwan University College of Public Health, Room 703, No. 17, Xu-Zhou Road, Taipei, 100, Taiwan.
- National Institute of Environmental Health Sciences, National Health Research Institutes, 10 F, Bldg F, 3 Yuanqu Street, Taipei, 11503, Taiwan.
- Environmental and Occupational Medicine, National Taiwan University and NTU Hospital, Taipei, 100, Taiwan.
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5
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Effects of Na + Current and Mechanogated Channels in Myofibroblasts on Myocyte Excitability and Repolarization. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2016; 2016:6189374. [PMID: 27980607 PMCID: PMC5131562 DOI: 10.1155/2016/6189374] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Revised: 10/09/2016] [Accepted: 10/19/2016] [Indexed: 12/19/2022]
Abstract
Fibrotic remodeling, characterized by fibroblast phenotype switching, is often associated with atrial fibrillation and heart failure. This study aimed to investigate the effects on electrotonic myofibroblast-myocyte (Mfb-M) coupling on cardiac myocytes excitability and repolarization of the voltage-gated sodium channels (VGSCs) and single mechanogated channels (MGCs) in human atrial Mfbs. Mathematical modeling was developed from a combination of (1) models of the human atrial myocyte (including the stretch activated ion channel current, ISAC) and Mfb and (2) our formulation of currents through VGSCs (INa_Mfb) and MGCs (IMGC_Mfb) based upon experimental findings. The effects of changes in the intercellular coupling conductance, the number of coupled Mfbs, and the basic cycle length on the myocyte action potential were simulated. The results demonstrated that the integration of ISAC, INa_Mfb, and IMGC_Mfb reduced the amplitude of the myocyte membrane potential (Vmax) and the action potential duration (APD), increased the depolarization of the resting myocyte membrane potential (Vrest), and made it easy to trigger spontaneous excitement in myocytes. For Mfbs, significant electrotonic depolarizations were exhibited with the addition of INa_Mfb and IMGC_Mfb. Our results indicated that ISAC, INa_Mfb, and IMGC_Mfb significantly influenced myocytes and Mfbs properties and should be considered in future cardiac pathological mathematical modeling.
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Johnson RG, Le HC, Evenson K, Loberg SW, Myslajek TM, Prabhu A, Manley AM, O’Shea C, Grunenwald H, Haddican M, Fitzgerald PM, Robinson T, Cisterna BA, Sáez JC, Liu TF, Laird DW, Sheridan JD. Connexin Hemichannels: Methods for Dye Uptake and Leakage. J Membr Biol 2016; 249:713-741. [DOI: 10.1007/s00232-016-9925-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Accepted: 08/22/2016] [Indexed: 01/18/2023]
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Mahoney VM, Mezzano V, Morley GE. A review of the literature on cardiac electrical activity between fibroblasts and myocytes. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2015; 120:128-33. [PMID: 26713556 DOI: 10.1016/j.pbiomolbio.2015.12.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Revised: 11/12/2015] [Accepted: 12/16/2015] [Indexed: 12/13/2022]
Abstract
Myocardial injuries often lead to fibrotic deposition. This review presents evidence supporting the concept that fibroblasts in the heart electrically couple to myocytes.
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Affiliation(s)
- Vanessa M Mahoney
- Leon H. Charney Division of Cardiology, Department of Medicine, New York University School of Medicine, New York, NY 10016, USA
| | - Valeria Mezzano
- Leon H. Charney Division of Cardiology, Department of Medicine, New York University School of Medicine, New York, NY 10016, USA
| | - Gregory E Morley
- Leon H. Charney Division of Cardiology, Department of Medicine, New York University School of Medicine, New York, NY 10016, USA.
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Abramochkin DV, Lozinsky IT, Kamkin A. Influence of mechanical stress on fibroblast-myocyte interactions in mammalian heart. J Mol Cell Cardiol 2014; 70:27-36. [PMID: 24389344 DOI: 10.1016/j.yjmcc.2013.12.020] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Revised: 12/18/2013] [Accepted: 12/24/2013] [Indexed: 12/18/2022]
Abstract
Cardiac fibroblasts are an essential component of cardiac tissue. These cells not only produce the extracellular matrix, but also are electrically and mechanically coupled with cardiomyocytes. In this way, fibroblasts can influence the electrical activity of cardiomyocytes. Cardiac fibroblasts cannot generate action potentials, but their membrane potential is controlled by mechanical stretch or compression of the surrounding myocardium which in turn affects their interaction with myocytes and the way myocytes respond to mechanical stress. This review discusses the electrical properties of cardiac fibroblasts, the present evidence of fibroblast-myocyte coupling and the way in which these cells respond to mechanical stress. This article is part of a Special Issue entitled "Myocyte-Fibroblast Signalling in Myocardium."
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Affiliation(s)
- Denis V Abramochkin
- Department of Fundamental and Applied Physiology, Russian National Research Medical University, Ostrovityanova str., 1, Moscow, Russia; Department of Human and Animal Physiology, Moscow State University, Leninskiye Gory, 1, 12, Moscow, Russia.
| | - Ilya T Lozinsky
- Department of Fundamental and Applied Physiology, Russian National Research Medical University, Ostrovityanova str., 1, Moscow, Russia
| | - Andre Kamkin
- Department of Fundamental and Applied Physiology, Russian National Research Medical University, Ostrovityanova str., 1, Moscow, Russia
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Link MS, Luttmann-Gibson H, Schwartz J, Mittleman MA, Wessler B, Gold DR, Dockery DW, Laden F. Acute exposure to air pollution triggers atrial fibrillation. J Am Coll Cardiol 2013; 62:816-25. [PMID: 23770178 DOI: 10.1016/j.jacc.2013.05.043] [Citation(s) in RCA: 135] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2012] [Revised: 05/22/2013] [Accepted: 05/28/2013] [Indexed: 11/17/2022]
Abstract
OBJECTIVES This study sought to evaluate the association of air pollution with the onset of atrial fibrillation (AF). BACKGROUND Air pollution in general and more specifically particulate matter has been associated with cardiovascular events. Although ventricular arrhythmias are traditionally thought to convey the increased cardiovascular risk, AF may also contribute. METHODS Patients with dual chamber implantable cardioverter-defibrillators (ICDs) were enrolled and followed prospectively. The association of AF onset with air quality including ambient particulate matter <2.5 μm aerodynamic diameter (PM2.5), black carbon, sulfate, particle number, NO2, SO2, and O3 in the 24 h prior to the arrhythmia was examined utilizing a case-crossover analysis. In sensitivity analyses, associations with air pollution between 2 and 48 h prior to the AF were examined. RESULTS Of 176 patients followed for an average of 1.9 years, 49 patients had 328 episodes of AF lasting ≥ 30 s. Positive but nonsignificant associations were found for PM2.5 in the prior 24 h, but stronger associations were found with shorter exposure windows. The odds of AF increased by 26% (95% confidence interval: 8% to 47%) for each 6.0 μg/m(3) increase in PM2.5 in the 2 h prior to the event (p = 0.004). The odds of AF were highest at the upper quartile of mean PM2.5. CONCLUSIONS PM was associated with increased odds of AF onset within hours following exposure in patients with known cardiac disease. Air pollution is an acute trigger of AF, likely contributing to the pollution-associated adverse cardiac outcomes observed in epidemiological studies.
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Affiliation(s)
- Mark S Link
- Cardiac Arrhythmia Service, Division of Cardiology, Tufts Medical Center, Tufts University School of Medicine, Boston, Massachusetts 02459, USA.
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10
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Benamer N, Vasquez C, Mahoney VM, Steinhardt MJ, Coetzee WA, Morley GE. Fibroblast KATP currents modulate myocyte electrophysiology in infarcted hearts. Am J Physiol Heart Circ Physiol 2013; 304:H1231-9. [PMID: 23436329 DOI: 10.1152/ajpheart.00878.2012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cardiac metabolism remains altered for an extended period of time after myocardial infarction. Studies have shown fibroblasts from normal hearts express KATP channels in culture. It is unknown whether fibroblasts from infarcted hearts express KATP channels and whether these channels contribute to scar and border zone electrophysiology. KATP channel subunit expression levels were determined in fibroblasts isolated from normal hearts (Fb), and scar (sMI-Fb) and remote (rMI-Fb) regions of left anterior descending coronary artery (LAD) ligated rat hearts. Whole cell KATP current density was determined with patch clamp. Action potential duration (APD) was measured with optical mapping in myocyte-only cultures and heterocellular cultures with fibroblasts with and without 100 μmol/l pinacidil. Whole heart optical mapping was used to assess KATP channel activity following LAD ligation. Pinacidil activated a potassium current (35.4 ± 7.5 pA/pF at 50 mV) in sMI-Fb that was inhibited with 10 μmol/l glibenclamide. Kir6.2 and SUR2 transcript levels were elevated in sMI-Fb. Treatment with Kir6.2 short interfering RNA decreased KATP currents (87%) in sMI-Fb. Treatment with pinacidil decreased APD (26%) in co-cultures with sMI-Fb. APD values were prolonged in LAD ligated hearts after perfusion with glibenclamide. KATP channels are present in fibroblasts from the scar and border zones of infarcted hearts. Activation of fibroblast KATP channels could modulate the electrophysiological substrate beyond the acute ischemic event. Targeting fibroblast KATP channels could represent a novel therapeutic approach to modify border zone electrophysiology after cardiac injury.
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Affiliation(s)
- Najate Benamer
- Leon H. Charney Division of Cardiology, New York University School of Medicine, New York, New York 10016, USA
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11
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Chatelier A, Mercier A, Tremblier B, Thériault O, Moubarak M, Benamer N, Corbi P, Bois P, Chahine M, Faivre JF. A distinct de novo expression of Nav1.5 sodium channels in human atrial fibroblasts differentiated into myofibroblasts. J Physiol 2012; 590:4307-19. [PMID: 22802584 DOI: 10.1113/jphysiol.2012.233593] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Fibroblasts play a major role in heart physiology. They are at the origin of the extracellular matrix renewal and production of various paracrine and autocrine factors. In pathological conditions, fibroblasts proliferate, migrate and differentiate into myofibroblasts leading to cardiac fibrosis. This differentiated status is associated with changes in expression profile leading to neo-expression of proteins such as ionic channels. The present study investigates further electrophysiological changes associated with fibroblast differentiation focusing on the activity of voltage-gated sodium channels in human atrial fibroblasts and myofibroblasts. Using the patch clamp technique we show that human atrial myofibroblasts display a fast inward voltage gated sodium current with a density of 13.28 ± 2.88 pA pF(-1) whereas no current was detectable in non-differentiated fibroblasts. Quantitative RT-PCR reveals a large amount of transcripts encoding the Na(v)1.5 α-subunit with a fourfold increased expression level in myofibroblasts when compared to fibroblasts. Accordingly, half of the current was blocked by 1 μm of tetrodotoxin and immunocytochemistry experiments reveal the presence of Na(v)1.5 proteins. Overall, this current exhibits similar biophysical characteristics to sodium currents found in cardiac myocytes except for the window current that is enlarged for potentials between -100 and -20 mV. Since fibrosis is one of the fundamental mechanisms implicated in atrial fibrillation, it is of great interest to investigate how this current could influence myofibroblast properties. Moreover, since several Na(v)1.5 mutations are related to cardiac pathologies, this study offers a new avenue on the fibroblasts involvement of these mutations.
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Affiliation(s)
- Aurélien Chatelier
- Institut de Physiologie et Biologie Cellulaires, FRE 3511, CNRS/Université de Poitiers, Poitiers, France.
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Takahashi K, Sakamoto K, Kimura J. Hypoxic stress induces transient receptor potential melastatin 2 (TRPM2) channel expression in adult rat cardiac fibroblasts. J Pharmacol Sci 2012; 118:186-97. [PMID: 22293297 DOI: 10.1254/jphs.11128fp] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022] Open
Abstract
When cardiac tissue is exposed to hypoxia, myocytes are damaged, while fibroblasts are activated. However, it is unknown what changes are induced by hypoxia in cardiac fibroblasts. In this study, using the whole cell patch-clamp technique, we investigated the effect of hypoxia on membrane currents in fibroblasts primarily cultured from adult rat hearts. Cardiac fibroblasts were incubated for 24 h under normoxic or hypoxic conditions using Anaeropack. Hypoxia increased a current which reversed at around -20 mV in the cardiac fibroblasts. This current was inhibited by clotrimazole, which is an inhibitor of transient receptor potential melastatin 2 (TRPM2) channel and intermediate-conductance Ca(2+)-activated K(+) channel (KCa3.1). ADP ribose in the pipette solution enhanced this current. Quantitative RT-PCR revealed that mRNA of TRPM2, but not that of KCa3.1, was increased by hypoxia. RNA interference of TRPM2 prevented the development of the hypoxia-induced current. H(2)O(2), an activator of TRPM2 channel, induced a higher [Ca(2+)](i) elevation in hypoxia-exposed cardiac fibroblasts than that in normoxia-exposed cells. We conclude that hypoxia induces TRPM2 channel expression in adult rat cardiac fibroblasts.
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Affiliation(s)
- Kenji Takahashi
- Department of Pharmacology, Fukushima Medical University, School of Medicine, Japan.
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Nguyen TP, Xie Y, Garfinkel A, Qu Z, Weiss JN. Arrhythmogenic consequences of myofibroblast-myocyte coupling. Cardiovasc Res 2011; 93:242-51. [PMID: 22049532 DOI: 10.1093/cvr/cvr292] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
AIMS Fibrosis is known to promote cardiac arrhythmias by disrupting myocardial structure. Given recent evidence that myofibroblasts form gap junctions with myocytes at least in co-cultures, we investigated whether myofibroblast-myocyte coupling can promote arrhythmia triggers, such as early afterdepolarizations (EADs), by directly influencing myocyte electrophysiology. METHODS AND RESULTS Using the dynamic voltage clamp technique, patch-clamped adult rabbit ventricular myocytes were electrotonically coupled to one or multiple virtual fibroblasts or myofibroblasts programmed with eight combinations of capacitance, membrane resistance, resting membrane potential, and gap junction coupling resistance, spanning physiologically realistic ranges. Myocytes were exposed to oxidative (1 mmol/L H(2)O(2)) or ionic (2.7 mmol/L hypokalaemia) stress to induce bradycardia-dependent EADs. In the absence of myofibroblast-myocyte coupling, EADs developed during slow pacing (6 s), but were completely suppressed by faster pacing (1 s). However, in the presence of myofibroblast-myocyte coupling, EADs could no longer be suppressed by rapid pacing, especially when myofibroblast resting membrane potential was depolarized (-25 mV). Analysis of the myofibroblast-myocyte virtual gap junction currents revealed two components: an early transient-outward I(to)-like current and a late sustained current. Selective elimination of the I(to)-like component prevented EADs, whereas selective elimination of the late component did not. CONCLUSION Coupling of myocytes to myofibroblasts promotes EAD formation as a result of a mismatch in early vs. late repolarization reserve caused by the I(to)-like component of the gap junction current. These cellular and ionic mechanisms may contribute to the pro-arrhythmic risk in fibrotic hearts.
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Affiliation(s)
- Thao P Nguyen
- UCLA Cardiovascular Research Laboratory, Division of Cardiology, Department of Medicine, Los Angeles, CA, USA
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Miragoli M, Kadir SHSA, Sheppard MN, Salvarani N, Virta M, Wells S, Lab MJ, Nikolaev VO, Moshkov A, Hague WM, Rohr S, Williamson C, Gorelik J. A protective antiarrhythmic role of ursodeoxycholic acid in an in vitro rat model of the cholestatic fetal heart. Hepatology 2011; 54:1282-92. [PMID: 21809354 PMCID: PMC4900448 DOI: 10.1002/hep.24492] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2011] [Accepted: 06/02/2011] [Indexed: 12/27/2022]
Abstract
UNLABELLED Intrahepatic cholestasis of pregnancy may be complicated by fetal arrhythmia, fetal hypoxia, preterm labor, and, in severe cases, intrauterine death. The precise etiology of fetal death is not known. However, taurocholate has been demonstrated to cause arrhythmia and abnormal calcium dynamics in cardiomyocytes. To identify the underlying reason for increased susceptibility of fetal cardiomyocytes to arrhythmia, we studied myofibroblasts (MFBs), which appear during structural remodeling of the adult diseased heart. In vitro, they depolarize rat cardiomyocytes via heterocellular gap junctional coupling. Recently, it has been hypothesized that ventricular MFBs might appear in the developing human heart, triggered by physiological fetal hypoxia. However, their presence in the fetal heart (FH) and their proarrhythmogenic effects have not been systematically characterized. Immunohistochemistry demonstrated that ventricular MFBs transiently appear in the human FH during gestation. We established two in vitro models of the maternal heart (MH) and FH, both exposed to increasing doses of taurocholate. The MH model consisted of confluent strands of rat cardiomyocytes, whereas for the FH model, we added cardiac MFBs on top of cardiomyocytes. Taurocholate in the FH model, but not in the MH model, slowed conduction velocity from 19 to 9 cm/s, induced early after depolarizations, and resulted in sustained re-entrant arrhythmias. These arrhythmic events were prevented by ursodeoxycholic acid, which hyperpolarized MFB membrane potential by modulating potassium conductance. CONCLUSION These results illustrate that the appearance of MFBs in the FH may contribute to arrhythmias. The above-described mechanism represents a new therapeutic approach for cardiac arrhythmias at the level of MFB.
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Affiliation(s)
- Michele Miragoli
- National Heart and Lung Institute, Imperial College London, London, England
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15
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Fuster V, Rydén LE, Cannom DS, Crijns HJ, Curtis AB, Ellenbogen KA, Halperin JL, Kay GN, Le Huezey JY, Lowe JE, Olsson SB, Prystowsky EN, Tamargo JL, Wann LS. 2011 ACCF/AHA/HRS Focused Updates Incorporated Into the ACC/AHA/ESC 2006 Guidelines for the Management of Patients With Atrial Fibrillation. Circulation 2011; 123:e269-367. [PMID: 21382897 DOI: 10.1161/cir.0b013e318214876d] [Citation(s) in RCA: 595] [Impact Index Per Article: 45.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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16
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Fuster V, Rydén LE, Cannom DS, Crijns HJ, Curtis AB, Ellenbogen KA, Halperin JL, Kay GN, Le Huezey JY, Lowe JE, Olsson SB, Prystowsky EN, Tamargo JL, Wann LS. 2011 ACCF/AHA/HRS Focused Updates Incorporated Into the ACC/AHA/ESC 2006 Guidelines for the Management of Patients With Atrial Fibrillation. J Am Coll Cardiol 2011; 57:e101-98. [PMID: 21392637 DOI: 10.1016/j.jacc.2010.09.013] [Citation(s) in RCA: 642] [Impact Index Per Article: 49.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Large RJ, Hollywood MA, Sergeant GP, Thornbury KD, Bourke S, Levick JR, McHale NG. Ionic currents in intimal cultured synoviocytes from the rabbit. Am J Physiol Cell Physiol 2010; 299:C1180-94. [PMID: 20720182 PMCID: PMC2980311 DOI: 10.1152/ajpcell.00028.2010] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Hyaluronan, a joint lubricant and regulator of synovial fluid content, is secreted by fibroblast-like synoviocytes lining the joint cavity, and secretion is greatly stimulated by Ca2+-dependent protein kinase C. This study aimed to define synoviocyte membrane currents and channels that may influence synoviocyte Ca2+ dynamics. Resting membrane potential ranged from −30 mV to −66 mV (mean −45 ± 8.60 mV, n = 40). Input resistance ranged from 0.54 GΩ to 2.6 GΩ (mean 1.28 ± 0.57 GΩ; ν = 33). Cell capacitance averaged 97.97 ± 5.93 pF. Voltage clamp using Cs+ pipette solution yielded a transient inward current that disappeared in Ca2+-free solutions and was blocked by 1 μM nifedipine, indicating an L-type calcium current. The current was increased fourfold by the calcium channel activator FPL 64176 (300 nM). Using K+ pipette solution, depolarizing steps positive to −40 mV evoked an outward current that showed kinetics and voltage dependence of activation and inactivation typical of the delayed rectifier potassium current. This was blocked by the nonspecific delayed rectifier blocker 4-aminopyridine. The synoviocytes expressed mRNA for four Kv1 subtypes (Kv1.1, Kv1.4, Kv1.5, and Kv1.6). Correolide (1 μM), margatoxin (100 nM), and α-dendrotoxin block these Kv1 subtypes, and all of these drugs significantly reduced synoviocyte outward current. The current was blocked most effectively by 50 nM κ-dendrotoxin, which is specific for channels containing a Kv1.1 subunit, indicating that Kv1.1 is critical, either as a homomultimeric channel or as a component of a heteromultimeric Kv1 channel. When 50 nM κ-dendrotoxin was added to current-clamped synoviocytes, the cells depolarized by >20 mV and this was accompanied by an increase in intracellular calcium concentration. Similarly, depolarization of the cells with high external potassium solution caused an increase in intracellular calcium, and this effect was greatly reduced by 1 μM nifedipine. In conclusion, fibroblast-like synoviocytes cultured from the inner synovium of the rabbit exhibit voltage-dependent inward and outward currents, including Ca2+ currents. They thus express ion channels regulating membrane Ca2+ permeability and electrochemical gradient. Since Ca2+-dependent kinases are major regulators of synovial hyaluronan secretion, the synoviocyte ion channels are likely to be important in the regulation of hyaluronan secretion.
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Affiliation(s)
- R J Large
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
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18
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Abstract
Cardiac fibroblasts are emerging as key components of normal cardiac function, as well as the response to stressors and injury. These most numerous cells of the heart interact with myocytes via paracrine mechanisms, alterations in extracellular matrix homeostasis, and direct cell-cell interactions. It is possible that they are a contributor to the inability of adult myocytes to proliferate and may influence cardiac progenitor biology. Furthering our understanding of how cardiac fibroblasts and myocytes interact may provide an avenue to novel treatments for heart failure prevention. This review discusses the most recent concepts in cardiac fibroblast-myocyte communication and areas of potential future research.
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Affiliation(s)
- Rahul Kakkar
- Cardiology Division, Massachusetts General Hospital, Department of Medicine, Harvard Medical School, Boston, MA, USA
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19
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Benamer N, Moha Ou Maati H, Demolombe S, Cantereau A, Delwail A, Bois P, Bescond J, Faivre JF. Molecular and functional characterization of a new potassium conductance in mouse ventricular fibroblasts. J Mol Cell Cardiol 2009; 46:508-17. [PMID: 19166858 DOI: 10.1016/j.yjmcc.2008.12.016] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2008] [Revised: 12/04/2008] [Accepted: 12/21/2008] [Indexed: 01/08/2023]
Abstract
The present work is aimed at identifying and characterizing, at a molecular and functional level, new ionic conductances potentially involved in the excitation-secretion coupling and proliferation of cardiac ventricular fibroblasts. Among potassium channel transcripts which were screened by high-throughput real-time PCR, SUR2 and Kir6.1 mRNAs were found to be the most abundant in ventricular fibroblasts. The corresponding proteins were not detected by western blot following 5 days of cell culture, but had appeared at 7 days, increasing with extended cell culture duration as the fibroblasts differentiated into myofibroblasts. Using the inside-out configuration of the patch-clamp technique, single potassium channels could be recorded. These had properties similar to those reported for SUR2/Kir6.1 channels, i.e. activation by pinacidil, inhibition by glibenclamide and activation by intracellular UDP. As already reported for this molecular signature, they were insensitive to intracellular ATP. In the whole-cell configuration, these channels have been shown to be responsible for a glibenclamide-sensitive macroscopic potassium current which can be activated not only by pinacidil, but also by nanomolar concentrations of the sphingolipid sphingosine-1-phosphate (S1P). The activation of this current resulted in an increase in cell proliferation and a decrease in IL-6 secretion, suggesting it has a functional role in situations where S1P increases. Overall, this work demonstrates for the first time that SUR2/Kir6.1 channels represent a significant potassium conductance in ventricular fibroblasts which may be activated in physio-pathological conditions and which may impact on fibroblast proliferation and function.
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Affiliation(s)
- Najate Benamer
- Institut de Physiologie et Biologie Cellulaires, CNRS UMR 6187, Université de Poitiers, France
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Raizman JE, Komljenovic J, Chang R, Deng C, Bedosky KM, Rattan SG, Cunnington RH, Freed DH, Dixon IMC. The participation of the Na+-Ca2+ exchanger in primary cardiac myofibroblast migration, contraction, and proliferation. J Cell Physiol 2008; 213:540-51. [PMID: 17541957 DOI: 10.1002/jcp.21134] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Cardiac ventricular myofibroblast motility, proliferation, and contraction contribute to post-myocardial infarct wound healing, infarct scar formation, and remodeling of the ventricle remote to the site of infarction. The Na+-Ca2+ exchanger (NCX1) is involved in altered calcium handling in cardiac myocytes during cardiac remodeling associated with heart failure, however, its role in cardiac myofibroblast cell function is unexplored. In this study we investigated the involvement of NCX1 as well as the role of non-selective-cation channels (NSCC) in cardiac myofibroblast cell function in vitro. Immunofluorescence and Western blots revealed that P1 cells upregulate alpha-smooth muscle actin (alphaSMA) and embryonic smooth muscle myosin heavy chain (SMemb) expression. NCX1 mRNA and proteins as well as Ca(v)1.2a protein are also expressed in P1 myofibroblasts. Myofibroblast motility in the presence of 50 ng/ml PDGF-BB was blocked with AG1296. Myofibroblast motility, contraction, and proliferation were sensitive to KB-R7943, a specific NCX1 reverse-mode inhibitor. In contrast, only proliferation and contraction, but not motility were sensitive to nifedipine, while gadolinium (NSCC blocker) was only associated with decreased motility. ML-7 treatment was associated with inhibition of the chemotactic response and contraction. Thus cardiac myofibroblast chemotaxis, contraction, and proliferation were sensitive to different pharmacologic treatments suggesting that regulation of transplasmalemmal calcium movements may be important in growth factor receptor-mediated processes. NCX1 may represent an important moiety in suppression of myofibroblast functions.
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Affiliation(s)
- Joshua E Raizman
- Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre and Department of Physiology, University of Manitoba, Winnipeg, Manitoba, Canada
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Abstract
Cardiac function is determined by the dynamic interaction of various cell types and the extracellular matrix that composes the heart. This interaction varies with the stage of development and the degree and duration of mechanical, chemical, and electrical signals between the various cell types and the ECM. Understanding how these complex signals interact at the molecular, cellular, and organ levels is critical to understanding the function of the heart under a variety of physiological and pathophysiological conditions. Quantitative approaches, both in vivo and in vitro, are essential to understand the dynamic interaction of mechanical, chemical, and electrical stimuli that govern cardiac function. The fibroblast can thus be a friend in normal function or a foe in pathophysiological conditions.
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Affiliation(s)
- Troy A Baudino
- Department of Cell and Developmental Biology and Anatomy, School of Medicine, University of South Carolina, Columbia, SC 29208, USA
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Fuster V, Rydén LE, Cannom DS, Crijns HJ, Curtis AB, Ellenbogen KA, Halperin JL, Le Heuzey JY, Kay GN, Lowe JE, Olsson SB, Prystowsky EN, Tamargo JL, Wann S, Smith SC, Jacobs AK, Adams CD, Anderson JL, Antman EM, Halperin JL, Hunt SA, Nishimura R, Ornato JP, Page RL, Riegel B, Priori SG, Blanc JJ, Budaj A, Camm AJ, Dean V, Deckers JW, Despres C, Dickstein K, Lekakis J, McGregor K, Metra M, Morais J, Osterspey A, Tamargo JL, Zamorano JL. ACC/AHA/ESC 2006 Guidelines for the Management of Patients with Atrial Fibrillation: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Revise the 2001 Guidelines for the Management of Patients With Atrial Fibrillation): developed in collaboration with the European Heart Rhythm Association and the Heart Rhythm Society. Circulation 2006; 114:e257-354. [PMID: 16908781 DOI: 10.1161/circulationaha.106.177292] [Citation(s) in RCA: 1381] [Impact Index Per Article: 76.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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El Chemaly A, Guinamard R, Demion M, Fares N, Jebara V, Faivre JF, Bois P. A voltage-activated proton current in human cardiac fibroblasts. Biochem Biophys Res Commun 2006; 340:512-6. [PMID: 16376300 DOI: 10.1016/j.bbrc.2005.12.038] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2005] [Accepted: 12/07/2005] [Indexed: 11/17/2022]
Abstract
A voltage-activated proton current in human cardiac fibroblasts, measured using the whole-cell recording configuration of the patch-clamp technique, is reported. Increasing the pH of the bathing solution shifted the current activation threshold to more negative potentials and increased both the current amplitude and its rate of activation. Changing the pH gradient by one unit caused a 51mV shift in the reversal potential of the current, demonstrating a high selectivity for protons of the channel carrying the current. Extracellularly applied Zn(2+) reversibly inhibited the current. Activation of the current contributes to the resting membrane conductance under conditions of intracellular acidosis. It is proposed that this current in cardiac fibroblasts is involved in the regulation of the intracellular pH and the membrane potential under physiological conditions as well as in response to pathological conditions such as ischemia.
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Affiliation(s)
- Antoun El Chemaly
- Institut de Physiologie et Biologie Cellulaires, UMR CNRS 6187, Université de Poitiers, 40 avenue du Recteur Pineau 86022 Poitiers Cedex, France
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Chilton L, Ohya S, Freed D, George E, Drobic V, Shibukawa Y, Maccannell KA, Imaizumi Y, Clark RB, Dixon IMC, Giles WR. K+ currents regulate the resting membrane potential, proliferation, and contractile responses in ventricular fibroblasts and myofibroblasts. Am J Physiol Heart Circ Physiol 2005; 288:H2931-9. [PMID: 15653752 DOI: 10.1152/ajpheart.01220.2004] [Citation(s) in RCA: 154] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Despite the important roles played by ventricular fibroblasts and myofibroblasts in the formation and maintenance of the extracellular matrix, neither the ionic basis for membrane potential nor the effect of modulating membrane potential on function has been analyzed in detail. In this study, whole cell patch-clamp experiments were done using ventricular fibroblasts and myofibroblasts. Time- and voltage-dependent outward K+ currents were recorded at depolarized potentials, and an inwardly rectifying K+ (Kir) current was recorded near the resting membrane potential (RMP) and at more hyperpolarized potentials. The apparent reversal potential of Kir currents shifted to more positive potentials as the external K+ concentration ([K+]o) was raised, and this Kir current was blocked by 100–300 μM Ba2+. RT-PCR measurements showed that mRNA for Kir2.1 was expressed. Accordingly, we conclude that Kir current is a primary determinant of RMP in both fibroblasts and myofibroblasts. Changes in [K+]o influenced fibroblast membrane potential as well as proliferation and contractile functions. Recordings made with a voltage-sensitive dye, DiBAC3(4), showed that 1.5 mM [K+]o resulted in a hyperpolarization, whereas 20 mM [K+]o produced a depolarization. Low [K+]o (1.5 mM) enhanced myofibroblast number relative to control (5.4 mM [K+]o). In contrast, 20 mM [K+]o resulted in a significant reduction in myofibroblast number. In separate assays, 20 mM [K+]o significantly enhanced contraction of collagen I gels seeded with myofibroblasts compared with control mechanical activity in 5.4 mM [K+]o. In combination, these results show that ventricular fibroblasts and myofibroblasts express a variety of K+ channel α-subunits and demonstrate that Kir current can modulate RMP and alter essential physiological functions.
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Affiliation(s)
- L Chilton
- Dept. of Bioengineering, Univ. of California-San Diego, 9500 Gilman Dr., La Jolla, CA 92093-0412, USA
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