1
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Medvedev RY, Afolabi SO, Turner DGP, Glukhov AV. Mechanisms of stretch-induced electro-anatomical remodeling and atrial arrhythmogenesis. J Mol Cell Cardiol 2024; 193:11-24. [PMID: 38797242 DOI: 10.1016/j.yjmcc.2024.05.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 05/15/2024] [Accepted: 05/21/2024] [Indexed: 05/29/2024]
Abstract
Atrial fibrillation (AF) is the most common cardiac rhythm disorder, often occurring in the setting of atrial distension and elevated myocardialstretch. While various mechano-electrochemical signal transduction pathways have been linked to AF development and progression, the underlying molecular mechanisms remain poorly understood, hampering AF therapies. In this review, we describe different aspects of stretch-induced electro-anatomical remodeling as seen in animal models and in patients with AF. Specifically, we focus on cellular and molecular mechanisms that are responsible for mechano-electrochemical signal transduction and the development of ectopic beats triggering AF from pulmonary veins, the most common source of paroxysmal AF. Furthermore, we describe structural changes caused by stretch occurring before and shortly after the onset of AF as well as during AF progression, contributing to longstanding forms of AF. We also propose mechanical stretch as a new dimension to the concept "AF begets AF", in addition to underlying diseases. Finally, we discuss the mechanisms of these electro-anatomical alterations in a search for potential therapeutic strategies and the development of novel antiarrhythmic drugs targeted at the components of mechano-electrochemical signal transduction not only in cardiac myocytes, but also in cardiac non-myocyte cells.
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Affiliation(s)
- Roman Y Medvedev
- Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI, USA
| | - Saheed O Afolabi
- Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI, USA; Department of Pharmacology and Therapeutics, University of Ilorin, Ilorin, Nigeria
| | - Daniel G P Turner
- Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI, USA
| | - Alexey V Glukhov
- Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI, USA.
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2
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Parvaresh H, Paczek K, Al-Bari MAA, Eid N. Mechanistic insights into fasting-induced autophagy in the aging heart. World J Cardiol 2024; 16:109-117. [PMID: 38576517 PMCID: PMC10989221 DOI: 10.4330/wjc.v16.i3.109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 02/01/2024] [Accepted: 03/04/2024] [Indexed: 03/21/2024] Open
Abstract
Autophagy is a prosurvival mechanism for the clearance of accumulated abnormal proteins, damaged organelles, and excessive lipids within mammalian cells. A growing body of data indicates that autophagy is reduced in aging cells. This reduction leads to various diseases, such as myocardial hypertrophy, infarction, and atherosclerosis. Recent studies in animal models of an aging heart showed that fasting-induced autophagy improved cardiac function and longevity. This improvement is related to autophagic clearance of damaged cellular components via either bulk or selective autophagy (such as mitophagy). In this editorial, we summarize the mechanisms of autophagy in normal and aging hearts. In addition, the protective effect of fasting-induced autophagy in cardiac aging has been highlighted.
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Affiliation(s)
- Hannaneh Parvaresh
- Department of Biology, Faculty of Science, Ferdowsi University of Mashhad, Mashhad 9177948974, Iran
| | - Katarzyna Paczek
- Department of Chiropractic, International Medical University, Kuala Lumpur 57000, Malaysia
| | | | - Nabil Eid
- Department of Anatomy, Division of Human Biology, School of Medicine, International Medical University, Kuala Lumpur 57000, Malaysia.
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3
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Kanaporis G, Blatter LA. Increased Risk for Atrial Alternans in Rabbit Heart Failure: The Role of Ca 2+/Calmodulin-Dependent Kinase II and Inositol-1,4,5-trisphosphate Signaling. Biomolecules 2023; 14:53. [PMID: 38254653 PMCID: PMC10813785 DOI: 10.3390/biom14010053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 12/18/2023] [Accepted: 12/23/2023] [Indexed: 01/24/2024] Open
Abstract
Heart failure (HF) increases the probability of cardiac arrhythmias, including atrial fibrillation (AF), but the mechanisms linking HF to AF are poorly understood. We investigated disturbances in Ca2+ signaling and electrophysiology in rabbit atrial myocytes from normal and failing hearts and identified mechanisms that contribute to the higher risk of atrial arrhythmias in HF. Ca2+ transient (CaT) alternans-beat-to-beat alternations in CaT amplitude-served as indicator of increased arrhythmogenicity. We demonstrate that HF atrial myocytes were more prone to alternans despite no change in action potentials duration and only moderate decrease of L-type Ca2+ current. Ca2+/calmodulin-dependent kinase II (CaMKII) inhibition suppressed CaT alternans. Activation of IP3 signaling by endothelin-1 (ET-1) and angiotensin II (Ang II) resulted in acute, but transient reduction of CaT amplitude and sarcoplasmic reticulum (SR) Ca2+ load, and lowered the alternans risk. However, prolonged exposure to ET-1 and Ang II enhanced SR Ca2+ release and increased the degree of alternans. Inhibition of IP3 receptors prevented the transient ET-1 and Ang II effects and by itself increased the degree of CaT alternans. Our data suggest that activation of CaMKII and IP3 signaling contribute to atrial arrhythmogenesis in HF.
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Affiliation(s)
| | - Lothar A. Blatter
- Department of Physiology & Biophysics, Rush University Medical Center, Chicago, IL 60612, USA;
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4
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Tang N, Tian W, Ma GY, Xiao X, Zhou L, Li ZZ, Liu XX, Li CY, Wu KH, Liu W, Wang XY, Gao YY, Yang X, Qi J, Li D, Liu Y, Chen WS, Gao J, Li XQ, Cao W. TRPC channels blockade abolishes endotoxemic cardiac dysfunction by hampering intracellular inflammation and Ca 2+ leakage. Nat Commun 2022; 13:7455. [PMID: 36460692 PMCID: PMC9718841 DOI: 10.1038/s41467-022-35242-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 11/23/2022] [Indexed: 12/04/2022] Open
Abstract
Intracellular Ca2+ dysregulation is a key marker in septic cardiac dysfunction; however, regulation of the classic Ca2+ regulatory modules cannot successfully abolish this symptom. Here we show that the knockout of transient receptor potential canonical (TRPC) channel isoforms TRPC1 and TRPC6 can ameliorate LPS-challenged heart failure and prolong survival in mice. The LPS-triggered Ca2+ release from the endoplasmic reticulum both in cardiomyocytes and macrophages is significantly inhibited by Trpc1 or Trpc6 knockout. Meanwhile, TRPC's molecular partner - calmodulin - is uncoupled during Trpc1 or Trpc6 deficiency and binds to TLR4's Pococurante site and atypical isoleucine-glutamine-like motif to block the inflammation cascade. Blocking the C-terminal CaM/IP3R binding domain in TRPC with chemical inhibitor could obstruct the Ca2+ leak and TLR4-mediated inflammation burst, demonstrating a cardioprotective effect in endotoxemia and polymicrobial sepsis. Our findings provide insight into the pathogenesis of endotoxemic cardiac dysfunction and suggest a novel approach for its treatment.
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Affiliation(s)
- Na Tang
- grid.144022.10000 0004 1760 4150Department of Pharmacy, School of Chemistry & Pharmacy, Northwest A&F University, Yangling, Shaanxi China ,grid.144022.10000 0004 1760 4150Shaanxi Key Laboratory of Natural Products & Chemical Biology, Northwest A&F University, Yangling, Shaanxi China
| | - Wen Tian
- grid.233520.50000 0004 1761 4404Department of Pharmacology, School of Pharmacy, Fourth Military Medical University, Xi’an, Shaanxi China ,grid.233520.50000 0004 1761 4404Key Laboratory of Gastrointestinal Pharmacology of Chinese Materia Medica of the State Administration of Traditional Chinese Medicine, Fourth Military Medical University, Xi’an, Shaanxi China
| | - Guang-Yuan Ma
- grid.144022.10000 0004 1760 4150Department of Pharmacy, School of Chemistry & Pharmacy, Northwest A&F University, Yangling, Shaanxi China ,grid.144022.10000 0004 1760 4150Shaanxi Key Laboratory of Natural Products & Chemical Biology, Northwest A&F University, Yangling, Shaanxi China
| | - Xiong Xiao
- grid.233520.50000 0004 1761 4404Department of Pharmacology, School of Pharmacy, Fourth Military Medical University, Xi’an, Shaanxi China ,grid.233520.50000 0004 1761 4404Key Laboratory of Gastrointestinal Pharmacology of Chinese Materia Medica of the State Administration of Traditional Chinese Medicine, Fourth Military Medical University, Xi’an, Shaanxi China
| | - Lei Zhou
- grid.144022.10000 0004 1760 4150Department of Pharmacy, School of Chemistry & Pharmacy, Northwest A&F University, Yangling, Shaanxi China ,grid.144022.10000 0004 1760 4150Shaanxi Key Laboratory of Natural Products & Chemical Biology, Northwest A&F University, Yangling, Shaanxi China
| | - Ze-Zhi Li
- grid.144022.10000 0004 1760 4150Department of Pharmacy, School of Chemistry & Pharmacy, Northwest A&F University, Yangling, Shaanxi China ,grid.144022.10000 0004 1760 4150Shaanxi Key Laboratory of Natural Products & Chemical Biology, Northwest A&F University, Yangling, Shaanxi China
| | - Xiao-Xiao Liu
- grid.233520.50000 0004 1761 4404Department of Pharmacology, School of Pharmacy, Fourth Military Medical University, Xi’an, Shaanxi China ,grid.233520.50000 0004 1761 4404Key Laboratory of Gastrointestinal Pharmacology of Chinese Materia Medica of the State Administration of Traditional Chinese Medicine, Fourth Military Medical University, Xi’an, Shaanxi China
| | - Chong-Yao Li
- grid.412262.10000 0004 1761 5538Department of Pharmacy, Xi’an No.3 Hospital, the Affiliated Hospital of Northwest University, Xi’an, Shaanxi China
| | - Ke-Han Wu
- grid.144022.10000 0004 1760 4150Department of Pharmacy, School of Chemistry & Pharmacy, Northwest A&F University, Yangling, Shaanxi China ,grid.144022.10000 0004 1760 4150Shaanxi Key Laboratory of Natural Products & Chemical Biology, Northwest A&F University, Yangling, Shaanxi China
| | - Wenjuan Liu
- grid.144022.10000 0004 1760 4150Department of Pharmacy, School of Chemistry & Pharmacy, Northwest A&F University, Yangling, Shaanxi China
| | - Xue-Ying Wang
- grid.233520.50000 0004 1761 4404Department of Pharmacology, School of Pharmacy, Fourth Military Medical University, Xi’an, Shaanxi China ,grid.233520.50000 0004 1761 4404Key Laboratory of Gastrointestinal Pharmacology of Chinese Materia Medica of the State Administration of Traditional Chinese Medicine, Fourth Military Medical University, Xi’an, Shaanxi China
| | - Yuan-Yuan Gao
- grid.233520.50000 0004 1761 4404Department of Pharmacology, School of Pharmacy, Fourth Military Medical University, Xi’an, Shaanxi China ,grid.233520.50000 0004 1761 4404Key Laboratory of Gastrointestinal Pharmacology of Chinese Materia Medica of the State Administration of Traditional Chinese Medicine, Fourth Military Medical University, Xi’an, Shaanxi China
| | - Xin Yang
- grid.144022.10000 0004 1760 4150Department of Pharmacy, School of Chemistry & Pharmacy, Northwest A&F University, Yangling, Shaanxi China ,grid.144022.10000 0004 1760 4150Shaanxi Key Laboratory of Natural Products & Chemical Biology, Northwest A&F University, Yangling, Shaanxi China
| | - Jianzhao Qi
- grid.144022.10000 0004 1760 4150Shaanxi Key Laboratory of Natural Products & Chemical Biology, Northwest A&F University, Yangling, Shaanxi China
| | - Ding Li
- grid.144022.10000 0004 1760 4150Shaanxi Key Laboratory of Natural Products & Chemical Biology, Northwest A&F University, Yangling, Shaanxi China
| | - Yang Liu
- grid.233520.50000 0004 1761 4404Department of Cardiovascular Surgery, Xijing Hospital, Fourth Military Medical University, Xi’an, Shaanxi China
| | - Wen-Sheng Chen
- grid.233520.50000 0004 1761 4404Department of Cardiovascular Surgery, Xijing Hospital, Fourth Military Medical University, Xi’an, Shaanxi China ,Department of Cardiovascular Surgery, Xi’an Gaoxin Hospital, Xi’an, Shaanxi China
| | - Jinming Gao
- grid.144022.10000 0004 1760 4150Department of Pharmacy, School of Chemistry & Pharmacy, Northwest A&F University, Yangling, Shaanxi China ,grid.144022.10000 0004 1760 4150Shaanxi Key Laboratory of Natural Products & Chemical Biology, Northwest A&F University, Yangling, Shaanxi China
| | - Xiao-Qiang Li
- grid.233520.50000 0004 1761 4404Department of Pharmacology, School of Pharmacy, Fourth Military Medical University, Xi’an, Shaanxi China ,grid.233520.50000 0004 1761 4404Key Laboratory of Gastrointestinal Pharmacology of Chinese Materia Medica of the State Administration of Traditional Chinese Medicine, Fourth Military Medical University, Xi’an, Shaanxi China
| | - Wei Cao
- grid.144022.10000 0004 1760 4150Department of Pharmacy, School of Chemistry & Pharmacy, Northwest A&F University, Yangling, Shaanxi China ,grid.144022.10000 0004 1760 4150Shaanxi Key Laboratory of Natural Products & Chemical Biology, Northwest A&F University, Yangling, Shaanxi China
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5
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Demydenko K, Ekhteraei-Tousi S, Roderick HL. Inositol 1,4,5-trisphosphate receptors in cardiomyocyte physiology and disease. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210319. [PMID: 36189803 PMCID: PMC9527928 DOI: 10.1098/rstb.2021.0319] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The contraction of cardiac muscle underlying the pumping action of the heart is mediated by the process of excitation-contraction coupling (ECC). While triggered by Ca2+ entry across the sarcolemma during the action potential, it is the release of Ca2+ from the sarcoplasmic reticulum (SR) intracellular Ca2+ store via ryanodine receptors (RyRs) that plays the major role in induction of contraction. Ca2+ also acts as a key intracellular messenger regulating transcription underlying hypertrophic growth. Although Ca2+ release via RyRs is by far the greatest contributor to the generation of Ca2+ transients in the cardiomyocyte, Ca2+ is also released from the SR via inositol 1,4,5-trisphosphate (InsP3) receptors (InsP3Rs). This InsP3-induced Ca2+ release modifies Ca2+ transients during ECC, participates in directing Ca2+ to the mitochondria, and stimulates the transcription of genes underlying hypertrophic growth. Central to these specific actions of InsP3Rs is their localization to responsible signalling microdomains, the dyad, the SR-mitochondrial interface and the nucleus. In this review, the various roles of InsP3R in cardiac (patho)physiology and the mechanisms by which InsP3 signalling selectively influences the different cardiomyocyte cell processes in which it is involved will be presented. This article is part of the theme issue ‘The cardiomyocyte: new revelations on the interplay between architecture and function in growth, health, and disease’.
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Affiliation(s)
- Kateryna Demydenko
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium
| | - Samaneh Ekhteraei-Tousi
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium
| | - H Llewelyn Roderick
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium
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6
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Bose SJ, Read MJ, Akerman E, Capel RA, Ayagama T, Russell A, Terrar DA, Zaccolo M, Burton RAB. Inhibition of adenylyl cyclase 1 by ST034307 inhibits IP3-evoked changes in sino-atrial node beat rate. Front Pharmacol 2022; 13:951897. [PMID: 36105228 PMCID: PMC9465815 DOI: 10.3389/fphar.2022.951897] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 08/01/2022] [Indexed: 11/13/2022] Open
Abstract
Atrial arrhythmias, such as atrial fibrillation (AF), are a major mortality risk and a leading cause of stroke. The IP3 signalling pathway has been proposed as an atrial-specific target for AF therapy, and atrial IP3 signalling has been linked to the activation of calcium sensitive adenylyl cyclases AC1 and AC8. We investigated the involvement of AC1 in the response of intact mouse atrial tissue and isolated guinea pig atrial and sino-atrial node (SAN) cells to the α-adrenoceptor agonist phenylephrine (PE) using the selective AC1 inhibitor ST034307. The maximum rate change of spontaneously beating mouse right atrial tissue exposed to PE was reduced from 14.5% to 8.2% (p = 0.005) in the presence of 1 μM ST034307, whereas the increase in tension generated in paced left atrial tissue in the presence of PE was not inhibited by ST034307 (Control = 14.2%, ST034307 = 16.3%; p > 0.05). Experiments were performed using isolated guinea pig atrial and SAN cells loaded with Fluo-5F-AM to record changes in calcium transients (CaT) generated by 10 μM PE in the presence and absence of 1 μM ST034307. ST034307 significantly reduced the beating rate of SAN cells (0.34-fold decrease; p = 0.003) but did not inhibit changes in CaT amplitude in response to PE in atrial cells. The results presented here demonstrate pharmacologically the involvement of AC1 in the downstream response of atrial pacemaker activity to α-adrenoreceptor stimulation and IP3R calcium release.
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Affiliation(s)
- Samuel J. Bose
- Department of Pharmacology, University of Oxford, Oxford, United Kingdom
| | - Matthew J. Read
- Department of Pharmacology, University of Oxford, Oxford, United Kingdom
| | - Emily Akerman
- Department of Pharmacology, University of Oxford, Oxford, United Kingdom
| | - Rebecca A. Capel
- Department of Pharmacology, University of Oxford, Oxford, United Kingdom
| | - Thamali Ayagama
- Department of Pharmacology, University of Oxford, Oxford, United Kingdom
| | - Angela Russell
- Department of Pharmacology, University of Oxford, Oxford, United Kingdom
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Oxford, United Kingdom
| | - Derek A. Terrar
- Department of Pharmacology, University of Oxford, Oxford, United Kingdom
| | - Manuela Zaccolo
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Rebecca A. B. Burton
- Department of Pharmacology, University of Oxford, Oxford, United Kingdom
- *Correspondence: Rebecca A. B. Burton,
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7
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Lkhagva B, Lin Y, Chen Y, Cheng W, Higa S, Kao Y, Chen Y. ZFHX3 knockdown dysregulates mitochondrial adaptations to tachypacing in atrial myocytes through enhanced oxidative stress and calcium overload. Acta Physiol (Oxf) 2021; 231:e13604. [PMID: 33332716 DOI: 10.1111/apha.13604] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 12/06/2020] [Accepted: 12/11/2020] [Indexed: 01/02/2023]
Abstract
AIM To investigate the role of zinc finger homeobox 3 gene (ZFHX3) in tachypacing-induced mitochondrial dysfunction and explore its molecular mechanisms and potential as a therapeutic target in atrial fibrillation (AF). METHODS Through a bioluminescent assay, a patch clamp, confocal fluorescence and fluorescence microscopy, microplate enzyme activity assays and Western blotting, we studied ATP and ADP production, mitochondrial electron transfer chain complex activities, ATP-sensitive potassium channels (IKATP ), mitochondrial oxidative stress, Ca2+ content, and protein expression in control and ZFHX3 knockdown (KD) HL-1 cells subjected to 1 and 5-Hz pacing for 24 hours. RESULTS Compared with 1-Hz pacing, 5-Hz pacing increased ATP and ADP production, IKATP , phosphorylated adenosine monophosphate-activated protein kinase and inositol 1,4,5-triphosphate (IP3 ) receptor (IP3 R) protein expression. Tachypacing induced mitochondrial oxidative stress and Ca2+ overload in both cell types. Furthermore, under 1- and 5-Hz pacing, ZFHX3 KD cells showed higher IKATP , ATP and ADP production, mitochondrial oxidative stress and Ca2+ content than control cells. Under 5-Hz pacing, 2-aminoethoxydiphenyl borate (2-APB; 3 μmol/L, an IP3 R inhibitor) and MitoTEMPO (10 µmol/L, a mitochondria-targeted antioxidant) reduced ADP and increased ATP production in both cell types; however, only 2-APB significantly reduced mitochondrial Ca2+ overload in control cells. Under 5-Hz pacing, mitochondrial oxidative stress was significantly reduced by both MitoTEMPO and 2-APB and only by 2-APB in control and ZFHX3 KD cells respectively. CONCLUSION ZFHX3 KD cells modulate mitochondrial adaptations to tachypacing in HL-1 cardiomyocytes through Ca2+ overload, oxidative stress and metabolic disorder. Targeting IP3 R signalling or oxidative stress could reduce AF.
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Affiliation(s)
- Baigalmaa Lkhagva
- Graduate Institute of Clinical Medicine College of Medicine Taipei Medical University Taipei Taiwan
| | - Yung‐Kuo Lin
- Division of Cardiology Department of Internal Medicine School of Medicine College of Medicine Taipei Medical University Taipei Taiwan
| | - Yao‐Chang Chen
- Department of Biomedical Engineering National Defense Medical Center Taipei Taiwan
| | - Wan‐Li Cheng
- Graduate Institute of Clinical Medicine College of Medicine Taipei Medical University Taipei Taiwan
| | - Satoshi Higa
- Cardiac Electrophysiology and Pacing Laboratory Division of Cardiovascular Medicine Makiminato Central Hospital Okinawa Japan
| | - Yu‐Hsun Kao
- Graduate Institute of Clinical Medicine College of Medicine Taipei Medical University Taipei Taiwan
- Department of Medical Education and Research Wan‐Fang Hospital Taipei Medical University Taipei Taiwan
| | - Yi‐Jen Chen
- Graduate Institute of Clinical Medicine College of Medicine Taipei Medical University Taipei Taiwan
- Cardiovascular Research CenterWan‐Fang HospitalTaipei Medical University Taipei Taiwan
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8
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Burton RAB, Terrar DA. Emerging Evidence for cAMP-calcium Cross Talk in Heart Atrial Nanodomains Where IP 3-Evoked Calcium Release Stimulates Adenylyl Cyclases. CONTACT (THOUSAND OAKS (VENTURA COUNTY, CALIF.)) 2021; 4:25152564211008341. [PMID: 37366374 PMCID: PMC10243587 DOI: 10.1177/25152564211008341] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 03/01/2021] [Accepted: 03/07/2021] [Indexed: 06/28/2023]
Abstract
Calcium handling is vital to normal physiological function in the heart. Human atrial arrhythmias, eg. atrial fibrillation, are a major morbidity and mortality burden, yet major gaps remain in our understanding of how calcium signaling pathways function and interact. Inositol trisphosphate (IP3) is a calcium-mobilizing second messenger and its agonist-induced effects have been observed in many tissue types. In the atria IP3 receptors (IR3Rs) residing on junctional sarcoplasmic reticulum augment cellular calcium transients and, when over-stimulated, lead to arrhythmogenesis. Recent studies have demonstrated that the predominant pathway for IP3 actions in atrial myocytes depends on stimulation of calcium-dependent forms of adenylyl cyclase (AC8 and AC1) by IP3-evoked calcium release from the sarcoplasmic reticulum. AC8 shows co-localisation with IP3Rs and AC1 appears to be nearby. These observations support crosstalk between calcium and cAMP pathways in nanodomains in atria. Similar mechanisms also appear to operate in the pacemaker region of the sinoatrial node. Here we discuss these significant advances in our understanding of atrial physiology and pathology, together with implications for the identification of potential novel targets and modulators for the treatment of atrial arrhythmias.
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Affiliation(s)
| | - Derek A. Terrar
- Department of Pharmacology, University of Oxford, Oxford, UK
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9
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Qi XY, Vahdati Hassani F, Hoffmann D, Xiao J, Xiong F, Villeneuve LR, Ljubojevic-Holzer S, Kamler M, Abu-Taha I, Heijman J, Bers DM, Dobrev D, Nattel S. Inositol Trisphosphate Receptors and Nuclear Calcium in Atrial Fibrillation. Circ Res 2020; 128:619-635. [PMID: 33375812 DOI: 10.1161/circresaha.120.317768] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
RATIONALE The mechanisms underlying atrial fibrillation (AF), the most common clinical arrhythmia, are poorly understood. Nucleoplasmic Ca2+ regulates gene expression, but the nature and significance of nuclear Ca2+-changes in AF are largely unknown. OBJECTIVE To elucidate mechanisms by which AF alters atrial-cardiomyocyte nuclear Ca2+ ([Ca2+]Nuc) and CaMKII (Ca2+/calmodulin-dependent protein kinase-II)-related signaling. METHODS AND RESULTS Atrial cardiomyocytes were isolated from control and AF dogs (kept in AF by atrial tachypacing [600 bpm × 1 week]). [Ca2+]Nuc and cytosolic [Ca2+] ([Ca2+]Cyto) were recorded via confocal microscopy. Diastolic [Ca2+]Nuc was greater than [Ca2+]Cyto under control conditions, while resting [Ca2+]Nuc was similar to [Ca2+]Cyto; both diastolic and resting [Ca2+]Nuc increased with AF. IP3R (Inositol-trisphosphate receptor) stimulation produced larger [Ca2+]Nuc increases in AF versus control cardiomyocytes, and IP3R-blockade suppressed the AF-related [Ca2+]Nuc differences. AF upregulated nuclear protein expression of IP3R1 (IP3R-type 1) and of phosphorylated CaMKII (immunohistochemistry and immunoblot) while decreasing the nuclear/cytosolic expression ratio for HDAC4 (histone deacetylase type-4). Isolated atrial cardiomyocytes tachypaced at 3 Hz for 24 hours mimicked AF-type [Ca2+]Nuc changes and L-type calcium current decreases versus 1-Hz-paced cardiomyocytes; these changes were prevented by IP3R knockdown with short-interfering RNA directed against IP3R1. Nuclear/cytosolic HDAC4 expression ratio was decreased by 3-Hz pacing, while nuclear CaMKII phosphorylation was increased. Either CaMKII-inhibition (by autocamtide-2-related peptide) or IP3R-knockdown prevented the CaMKII-hyperphosphorylation and nuclear-to-cytosolic HDAC4 shift caused by 3-Hz pacing. In human atrial cardiomyocytes from AF patients, nuclear IP3R1-expression was significantly increased, with decreased nuclear/nonnuclear HDAC4 ratio. MicroRNA-26a was predicted to target ITPR1 (confirmed by luciferase assay) and was downregulated in AF atrial cardiomyocytes; microRNA-26a silencing reproduced AF-induced IP3R1 upregulation and nuclear diastolic Ca2+-loading. CONCLUSIONS AF increases atrial-cardiomyocyte nucleoplasmic [Ca2+] by IP3R1-upregulation involving miR-26a, leading to enhanced IP3R1-CaMKII-HDAC4 signaling and L-type calcium current downregulation. Graphic Abstract: A graphic abstract is available for this article.
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Affiliation(s)
- Xiao-Yan Qi
- Medicine, Montreal Heart Institute, Université de Montréal, Canada (X.-Y.Q., F.V.H., J.X., F.X., L.R.V., D.D., S.N.)
| | - Faezeh Vahdati Hassani
- Medicine, Montreal Heart Institute, Université de Montréal, Canada (X.-Y.Q., F.V.H., J.X., F.X., L.R.V., D.D., S.N.)
| | - Dennis Hoffmann
- Institute of Pharmacology, West German Heart and Vascular Center, Medical Faculty, University Duisburg-Essen, Germany (D.H., I.A.-T., J.H., D.D., S.N.)
| | - Jiening Xiao
- Medicine, Montreal Heart Institute, Université de Montréal, Canada (X.-Y.Q., F.V.H., J.X., F.X., L.R.V., D.D., S.N.)
| | - Feng Xiong
- Medicine, Montreal Heart Institute, Université de Montréal, Canada (X.-Y.Q., F.V.H., J.X., F.X., L.R.V., D.D., S.N.)
| | - Louis R Villeneuve
- Medicine, Montreal Heart Institute, Université de Montréal, Canada (X.-Y.Q., F.V.H., J.X., F.X., L.R.V., D.D., S.N.)
| | | | - Markus Kamler
- Departments of Thoracic and Cardiovascular Surgery Huttrop (M.K.)
| | - Issam Abu-Taha
- Institute of Pharmacology, West German Heart and Vascular Center, Medical Faculty, University Duisburg-Essen, Germany (D.H., I.A.-T., J.H., D.D., S.N.)
| | - Jordi Heijman
- Institute of Pharmacology, West German Heart and Vascular Center, Medical Faculty, University Duisburg-Essen, Germany (D.H., I.A.-T., J.H., D.D., S.N.).,Cardiology, Cardiovascular Research Institute Maastricht, Faculty of Health, Medicine, and Life Sciences, Maastricht University, the Netherlands (J.H.)
| | - Donald M Bers
- Physiology, University of California, Davis (S.L.-H., D.M.B.)
| | - Dobromir Dobrev
- Medicine, Montreal Heart Institute, Université de Montréal, Canada (X.-Y.Q., F.V.H., J.X., F.X., L.R.V., D.D., S.N.).,Institute of Pharmacology, West German Heart and Vascular Center, Medical Faculty, University Duisburg-Essen, Germany (D.H., I.A.-T., J.H., D.D., S.N.)
| | - Stanley Nattel
- Medicine, Montreal Heart Institute, Université de Montréal, Canada (X.-Y.Q., F.V.H., J.X., F.X., L.R.V., D.D., S.N.).,Institute of Pharmacology, West German Heart and Vascular Center, Medical Faculty, University Duisburg-Essen, Germany (D.H., I.A.-T., J.H., D.D., S.N.).,Pharmacology, McGill University Montreal, Canada (S.N.).,IHU LIRYC, Bordeaux, France (S.N.)
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10
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Capel RA, Bose SJ, Collins TP, Rajasundaram S, Ayagama T, Zaccolo M, Burton RAB, Terrar DA. IP 3-mediated Ca 2+ release regulates atrial Ca 2+ transients and pacemaker function by stimulation of adenylyl cyclases. Am J Physiol Heart Circ Physiol 2020; 320:H95-H107. [PMID: 33064562 PMCID: PMC7864251 DOI: 10.1152/ajpheart.00380.2020] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Inositol trisphosphate (IP3) is a Ca2+-mobilizing second messenger shown to modulate atrial muscle contraction and is thought to contribute to atrial fibrillation. Cellular pathways underlying IP3 actions in cardiac tissue remain poorly understood, and the work presented here addresses the question whether IP3-mediated Ca2+ release from the sarcoplasmic reticulum is linked to adenylyl cyclase activity including Ca2+-stimulated adenylyl cyclases (AC1 and AC8) that are selectively expressed in atria and sinoatrial node (SAN). Immunocytochemistry in guinea pig atrial myocytes identified colocalization of type 2 IP3 receptors with AC8, while AC1 was located in close vicinity. Intracellular photorelease of IP3 by UV light significantly enhanced the amplitude of the Ca2+ transient (CaT) evoked by electrical stimulation of atrial myocytes (31 ± 6% increase 60 s after photorelease, n = 16). The increase in CaT amplitude was abolished by inhibitors of adenylyl cyclases (MDL-12,330) or protein kinase A (H89), showing that cAMP signaling is required for this effect of photoreleased IP3. In mouse, spontaneously beating right atrial preparations, phenylephrine, an α-adrenoceptor agonist with effects that depend on IP3-mediated Ca2+ release, increased the maximum beating rate by 14.7 ± 0.5%, n = 10. This effect was substantially reduced by 2.5 µmol/L 2-aminoethyl diphenylborinate and abolished by a low dose of MDL-12,330, observations which are again consistent with a functional interaction between IP3 and cAMP signaling involving Ca2+ stimulation of adenylyl cyclases in the SAN pacemaker. Understanding the interaction between IP3 receptor pathways and Ca2+-stimulated adenylyl cyclases provides important insights concerning acute mechanisms for initiation of atrial arrhythmias. NEW & NOTEWORTHY This study provides evidence supporting the proposal that IP3 signaling in cardiac atria and sinoatrial node involves stimulation of Ca2+-activated adenylyl cyclases (AC1 and AC8) by IP3-evoked Ca2+ release from junctional sarcoplasmic reticulum. AC8 and IP3 receptors are shown to be located close together, while AC1 is nearby. Greater understanding of these novel aspects of the IP3 signal transduction mechanism is important for future study in atrial physiology and pathophysiology, particularly atrial fibrillation.
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Affiliation(s)
- Rebecca A Capel
- Department of Pharmacology, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Samuel J Bose
- Department of Pharmacology, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Thomas P Collins
- Department of Pharmacology, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Skanda Rajasundaram
- Department of Pharmacology, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Thamali Ayagama
- Department of Pharmacology, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Manuela Zaccolo
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Rebecca-Ann Beatrice Burton
- Department of Pharmacology, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Derek A Terrar
- Department of Pharmacology, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
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11
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Luo Y, Liu X, Ma R, Wang Y, Zimering M, Pan Z. Circulating IgGs in Type 2 Diabetes with Atrial Fibrillation Induce IP 3-Mediated Calcium Elevation in Cardiomyocytes. iScience 2020; 23:101036. [PMID: 32315831 PMCID: PMC7170991 DOI: 10.1016/j.isci.2020.101036] [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: 08/30/2019] [Revised: 01/16/2020] [Accepted: 04/01/2020] [Indexed: 11/06/2022] Open
Abstract
Higher risk of cardiac arrhythmias including atrial fibrillation (AF) associates with type 2 diabetes mellitus (T2DM) with the underlying mechanism largely unknown. The present study reported a subset of circulating immunoglobulin G autoantibodies (IgGs) from patients with T2DM with AF (T2DM/AF)-induced intracellular calcium elevation in both human induced pluripotent stem cell (iPSC)-derived and mouse atrial cardiomyocytes, whereas (identical concentrations of) IgGs from patients with T2DM without AF could not. The IgG-evoked intracellular calcium elevation was insensitive to verapamil, mibefradil, or BTP-2, indicating calcium source from neither voltage-gated calcium channels nor store-operated calcium entry. On the other hand, pharmacological antagonism or genetic knockdown of inositol triphosphate (IP3) receptor significantly decreased T2DM/AF IgG-induced intracellular calcium elevation. Furthermore, pharmacological blockage of G protein-coupled receptor (GPCR), heterotrimeric G protein or phospholipase C dampened IgG-induced intracellular calcium elevation. Taken together, circulating IgGs from patients with T2DM/AF stimulated arrhythmogenic intracellular calcium elevation through IP3 pathway in atrial cardiomyocytes. Identification of cardiomyocyte-targeting IgGs in T2DM atrial fibrillation patients Induction of arrhythmogenic Ca2+ signaling by these IgGs Independent of voltage-gated or store-operated Ca2+ channels Involvement of GPCR-IP3-IP3R axis in IgG-evoked intracellular Ca2+ elevation
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Affiliation(s)
- Yanhong Luo
- Davis Heart and Lung Research Institute, Ohio State University-Wexner Medical Center, Columbus, OH 43210, USA; Department of Endocrinology, The Children's Hospital of Chongqing Medical University, Chongqing, P. R. China
| | - Xian Liu
- Department of Kinesiology, University of Texas at Arlington, Arlington, TX 76010, USA; College of Nursing and Health Innovation, University of Texas at Arlington, Arlington, TX 76010, USA
| | - Ruilian Ma
- Division of Regenerative Medicine Research, Department of Pathology and Laboratory Medicine, University of Cincinnati, Cincinnati, OH 45219, USA
| | - Yigang Wang
- Division of Regenerative Medicine Research, Department of Pathology and Laboratory Medicine, University of Cincinnati, Cincinnati, OH 45219, USA
| | - Mark Zimering
- Endocrinology, Veterans Affairs New Jersey Healthcare System, East Orange, NJ 07018, USA; Rutgers-Robert Wood Johnson Medical School, New Brunswick, NJ 08901, USA.
| | - Zui Pan
- Davis Heart and Lung Research Institute, Ohio State University-Wexner Medical Center, Columbus, OH 43210, USA; Department of Kinesiology, University of Texas at Arlington, Arlington, TX 76010, USA; College of Nursing and Health Innovation, University of Texas at Arlington, Arlington, TX 76010, USA.
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12
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Mijares A, Espinosa R, Adams J, Lopez JR. Increases in [IP3]i aggravates diastolic [Ca2+] and contractile dysfunction in Chagas' human cardiomyocytes. PLoS Negl Trop Dis 2020; 14:e0008162. [PMID: 32275663 PMCID: PMC7176279 DOI: 10.1371/journal.pntd.0008162] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 04/22/2020] [Accepted: 02/21/2020] [Indexed: 11/18/2022] Open
Abstract
Chagas cardiomyopathy is the most severe manifestation of human Chagas disease and represents the major cause of morbidity and mortality in Latin America. We previously demonstrated diastolic Ca2+ alterations in cardiomyocytes isolated from Chagas' patients to different degrees of cardiac dysfunction. In addition, we have found a significant elevation of diastolic [Na+]d in Chagas' cardiomyocytes (FCII>FCI) that was greater than control. Exposure of cardiomyocytes to agents that enhance inositol 1,4,5 trisphosphate (IP3) generation or concentration like endothelin (ET-1) or bradykinin (BK), or membrane-permeant myoinositol 1,4,5-trisphosphate hexakis(butyryloxy-methyl) esters (IP3BM) caused an elevation in diastolic [Ca2+] ([Ca2+]d) that was always greater in cardiomyocytes from Chagas' than non- Chagas' subjects, and the magnitude of the [Ca2+]d elevation in Chagas' cardiomyocytes was related to the degree of cardiac dysfunction. Incubation with xestospongin-C (Xest-C), a membrane-permeable selective blocker of the IP3 receptors (IP3Rs), significantly reduced [Ca2+]d in Chagas' cardiomyocytes but did not have a significant effect on non-Chagas' cells. The effects of ET-1, BK, and IP3BM on [Ca2+]d were not modified by the removal of extracellular [Ca2+]e. Furthermore, cardiomyocytes from Chagas' patients had a significant decrease in the sarcoplasmic reticulum (SR) Ca2+content compared to control (Control>FCI>FCII), a higher intracellular IP3 concentration ([IP3]i) and markedly depressed contractile properties compared to control cardiomyocytes. These results provide additional and convincing support about the implications of IP3 in the pathogenesis of Chagas cardiomyopathy in patients at different stages of chronic infection. Additionally, these findings open the door for novel therapeutic strategies oriented to improve cardiac function and quality of life of individuals suffering from chronic Chagas cardiomyopathy (CC).
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Affiliation(s)
- Alfredo Mijares
- Centro de Biofísica y Bioquímica, Instituto Venezolano de Investigaciones Científicas, Caracas, Venezuela
| | - Raúl Espinosa
- Departamento de Cardiología, Hospital Miguel Pérez Carreño, Instituto venezolano de los Seguros Sociales, Caracas, Venezuela
| | - José Adams
- Division of Neonatology, Mount Sinai, Medical Center, Miami, FL, United States of America
| | - José R. Lopez
- Department of Research, Mount Sinai, Medical Center, Miami, FL, United States of America
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13
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Gilbert G, Demydenko K, Dries E, Puertas RD, Jin X, Sipido K, Roderick HL. Calcium Signaling in Cardiomyocyte Function. Cold Spring Harb Perspect Biol 2020; 12:cshperspect.a035428. [PMID: 31308143 DOI: 10.1101/cshperspect.a035428] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Rhythmic increases in intracellular Ca2+ concentration underlie the contractile function of the heart. These heart muscle-wide changes in intracellular Ca2+ are induced and coordinated by electrical depolarization of the cardiomyocyte sarcolemma by the action potential. Originating at the sinoatrial node, conduction of this electrical signal throughout the heart ensures synchronization of individual myocytes into an effective cardiac pump. Ca2+ signaling pathways also regulate gene expression and cardiomyocyte growth during development and in pathology. These fundamental roles of Ca2+ in the heart are illustrated by the prevalence of altered Ca2+ homeostasis in cardiovascular diseases. Indeed, heart failure (an inability of the heart to support hemodynamic needs), rhythmic disturbances, and inappropriate cardiac growth all share an involvement of altered Ca2+ handling. The prevalence of these pathologies, contributing to a third of all deaths in the developed world as well as to substantial morbidity makes understanding the mechanisms of Ca2+ handling and dysregulation in cardiomyocytes of great importance.
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Affiliation(s)
- Guillaume Gilbert
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, BE3000 Leuven, Belgium
| | - Kateryna Demydenko
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, BE3000 Leuven, Belgium
| | - Eef Dries
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, BE3000 Leuven, Belgium
| | - Rosa Doñate Puertas
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, BE3000 Leuven, Belgium
| | - Xin Jin
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, BE3000 Leuven, Belgium
| | - Karin Sipido
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, BE3000 Leuven, Belgium
| | - H Llewelyn Roderick
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, BE3000 Leuven, Belgium
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14
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Abstract
Cardiovascular diseases are the most prominent maladies in aging societies. Indeed, aging promotes the structural and functional declines of both the heart and the blood circulation system. In this review, we revise the contribution of known longevity pathways to cardiovascular health and delineate the possibilities to interfere with them. In particular, we evaluate autophagy, the intracellular catabolic recycling system associated with life- and health-span extension. We present genetic models, pharmacological interventions, and dietary strategies that block, reduce, or enhance autophagy upon age-related cardiovascular deterioration. Caloric restriction or caloric restriction mimetics like metformin, spermidine, and rapamycin (all of which trigger autophagy) are among the most promising cardioprotective interventions during aging. We conclude that autophagy is a fundamental process to ensure cardiac and vascular health during aging and outline its putative therapeutic importance.
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Affiliation(s)
- Mahmoud Abdellatif
- From the Department of Cardiology, Medical University of Graz, Austria (M.A., S.S.)
| | - Simon Sedej
- From the Department of Cardiology, Medical University of Graz, Austria (M.A., S.S.).,BioTechMed Graz, Austria (S.S., D.C.-G., F.M.)
| | - Didac Carmona-Gutierrez
- BioTechMed Graz, Austria (S.S., D.C.-G., F.M.).,Institute of Molecular Biosciences, NAWI Graz, University of Graz, Austria (D.C.-G., F.M.)
| | - Frank Madeo
- BioTechMed Graz, Austria (S.S., D.C.-G., F.M.).,Institute of Molecular Biosciences, NAWI Graz, University of Graz, Austria (D.C.-G., F.M.)
| | - Guido Kroemer
- Equipe 11 Labellisée Ligue Contre le Cancer, Centre de Recherche des Cordeliers, Paris, France (G.K.).,Cell Biology and Metabolomics Platforms, Gustave Roussy Comprehensive Cancer Center, Villejuif, France (G.K.).,INSERM, U1138, Paris, France (G.K.).,Université Paris Descartes, Sorbonne Paris Cité, France (G.K.).,Université Pierre et Marie Curie, Paris, France (G.K.).,Pôle de Biologie, Hôpital Européen Georges Pompidou, Paris, France (G.K.).,Department of Women's and Children's Health, Karolinska Institute, Karolinska University Hospital, Stockholm, Sweden (G.K.)
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15
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Boknik P, Drzewiecki K, Eskandar J, Gergs U, Hofmann B, Treede H, Grote-Wessels S, Fabritz L, Kirchhof P, Fortmüller L, Müller FU, Schmitz W, Zimmermann N, Kirchhefer U, Neumann J. Evidence for Arrhythmogenic Effects of A 2A-Adenosine Receptors. Front Pharmacol 2019; 10:1051. [PMID: 31619997 PMCID: PMC6759833 DOI: 10.3389/fphar.2019.01051] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 08/20/2019] [Indexed: 12/26/2022] Open
Abstract
Adenosine can be released from the heart and may stimulate four different cardiac adenosine receptors. A receptor subtype that couples to the generation of cyclic adenosine monophosphate (cAMP) is the A2A-adenosine receptor (A2A-AR). To better understand its role in cardiac function, we studied mechanical and electrophysiological effects in transgenic mice that overexpress the human A2A-AR in cardiomyocytes (A2A-TG). We used isolated preparations from the left atrium, the right atrium, isolated perfused hearts with surface electrocardiogram (ECG) recording, and surface body ECG recordings of living mice. The hypothesized arrhythmogenic effects of transgenicity per se and A2A-AR stimulation were studied. We noted an increase in the incidence of supraventricular and ventricular arrhythmias under these conditions in A2A-TG. Moreover, we noted that the A2A-AR agonist CGS 21680 exerted positive inotropic effect in isolated human electrically driven (1 Hz) right atrial trabeculae carneae. We conclude that A2A-ARs are functional not only in A2A-TG but also in isolated human atrial preparations. A2A-ARs in A2A-TG per se and their stimulation can lead to cardiac arrhythmias not only in isolated cardiac preparations from A2A-TG but also in living A2A-TG.
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Affiliation(s)
- Peter Boknik
- Institut für Pharmakologie und Toxikologie, Universitätsklinikum Münster, Westfälische Wilhelms-Universität, Münster, Germany
| | - Katharina Drzewiecki
- Institut für Pharmakologie und Toxikologie, Universitätsklinikum Münster, Westfälische Wilhelms-Universität, Münster, Germany
| | - John Eskandar
- Institut für Pharmakologie und Toxikologie, Universitätsklinikum Münster, Westfälische Wilhelms-Universität, Münster, Germany
| | - Ulrich Gergs
- Institut für Pharmakologie und Toxikologie, Medizinische Fakultät, Martin-Luther-Universität Halle-Wittenberg, Halle, Germany
| | - Britt Hofmann
- Klinik für Herzchirurgie, Medizinische Fakultät, Martin-Luther-Universität Halle-Wittenberg, Halle, Germany
| | - Hendrik Treede
- Klinik für Herzchirurgie, Medizinische Fakultät, Martin-Luther-Universität Halle-Wittenberg, Halle, Germany
| | - Stephanie Grote-Wessels
- Institut für Pharmakologie und Toxikologie, Universitätsklinikum Münster, Westfälische Wilhelms-Universität, Münster, Germany
| | - Larissa Fabritz
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, United Kingdom.,University Hospitals Birmingham NHS Foundation Trust, Birmingham, United Kingdom
| | - Paulus Kirchhof
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, United Kingdom.,University Hospitals Birmingham NHS Foundation Trust, Birmingham, United Kingdom.,Sandwell and West Birmingham Hospital NHS Trust, Birmingham, United Kingdom
| | - Lisa Fortmüller
- Institute for Human Genetics, Genetic epidemiology, Universitätsklinikum Münster, Westfälische Wilhelms-Universität, Münster, Germany
| | - Frank Ulrich Müller
- Institut für Pharmakologie und Toxikologie, Universitätsklinikum Münster, Westfälische Wilhelms-Universität, Münster, Germany
| | - Wilhelm Schmitz
- Institut für Pharmakologie und Toxikologie, Universitätsklinikum Münster, Westfälische Wilhelms-Universität, Münster, Germany
| | | | - Uwe Kirchhefer
- Institut für Pharmakologie und Toxikologie, Universitätsklinikum Münster, Westfälische Wilhelms-Universität, Münster, Germany
| | - Joachim Neumann
- Institut für Pharmakologie und Toxikologie, Medizinische Fakultät, Martin-Luther-Universität Halle-Wittenberg, Halle, Germany
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16
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Vagos M, van Herck IGM, Sundnes J, Arevalo HJ, Edwards AG, Koivumäki JT. Computational Modeling of Electrophysiology and Pharmacotherapy of Atrial Fibrillation: Recent Advances and Future Challenges. Front Physiol 2018; 9:1221. [PMID: 30233399 PMCID: PMC6131668 DOI: 10.3389/fphys.2018.01221] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 08/13/2018] [Indexed: 12/19/2022] Open
Abstract
The pathophysiology of atrial fibrillation (AF) is broad, with components related to the unique and diverse cellular electrophysiology of atrial myocytes, structural complexity, and heterogeneity of atrial tissue, and pronounced disease-associated remodeling of both cells and tissue. A major challenge for rational design of AF therapy, particularly pharmacotherapy, is integrating these multiscale characteristics to identify approaches that are both efficacious and independent of ventricular contraindications. Computational modeling has long been touted as a basis for achieving such integration in a rapid, economical, and scalable manner. However, computational pipelines for AF-specific drug screening are in their infancy, and while the field is progressing quite rapidly, major challenges remain before computational approaches can fill the role of workhorse in rational design of AF pharmacotherapies. In this review, we briefly detail the unique aspects of AF pathophysiology that determine requirements for compounds targeting AF rhythm control, with emphasis on delimiting mechanisms that promote AF triggers from those providing substrate or supporting reentry. We then describe modeling approaches that have been used to assess the outcomes of drugs acting on established AF targets, as well as on novel promising targets including the ultra-rapidly activating delayed rectifier potassium current, the acetylcholine-activated potassium current and the small conductance calcium-activated potassium channel. Finally, we describe how heterogeneity and variability are being incorporated into AF-specific models, and how these approaches are yielding novel insights into the basic physiology of disease, as well as aiding identification of the important molecular players in the complex AF etiology.
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Affiliation(s)
- Márcia Vagos
- Computational Physiology Department, Simula Research Laboratory, Lysaker, Norway
- Department of Informatics, University of Oslo, Oslo, Norway
| | - Ilsbeth G. M. van Herck
- Computational Physiology Department, Simula Research Laboratory, Lysaker, Norway
- Department of Informatics, University of Oslo, Oslo, Norway
| | - Joakim Sundnes
- Computational Physiology Department, Simula Research Laboratory, Lysaker, Norway
- Center for Cardiological Innovation, Oslo, Norway
| | - Hermenegild J. Arevalo
- Computational Physiology Department, Simula Research Laboratory, Lysaker, Norway
- Center for Cardiological Innovation, Oslo, Norway
| | - Andrew G. Edwards
- Computational Physiology Department, Simula Research Laboratory, Lysaker, Norway
- Center for Cardiological Innovation, Oslo, Norway
| | - Jussi T. Koivumäki
- BioMediTech Institute and Faculty of Biomedical Sciences and Engineering, Tampere University of Technology, Tampere, Finland
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
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17
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Kim JC, Son MJ, Le QA, Woo SH. Role of inositol 1,4,5-trisphosphate receptor type 1 in ATP-induced nuclear Ca 2+ signal and hypertrophy in atrial myocytes. Biochem Biophys Res Commun 2018; 503:2998-3002. [PMID: 30122316 DOI: 10.1016/j.bbrc.2018.08.084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Accepted: 08/10/2018] [Indexed: 11/25/2022]
Abstract
Inositol 1,4,5-trisphosphate receptor type 1 (IP3R1) is expressed in atrial muscle, but not in ventricle, and they are abundant in the perinucleus. We investigated the role of IP3R1 in the regulations of local Ca2+ signal and cell size in HL-1 atrial myocytes under stimulation by IP3-generating chemical messenger, ATP. Assessment of nuclear and cytosolic Ca2+ signal using confocal Ca2+ imaging revealed that IP3 generation by ATP (1 mM) induced monophasic nuclear Ca2+ increase, followed by cytosolic Ca2+ oscillation. Genetic knock-down (KD) of IP3R1 eliminated the monophasic nuclear Ca2+ signal and slowed the cytosolic Ca2+ oscillation upon ATP exposure. Prolonged application of ATP as well as other known hypertrophic agonists (endothelin-1 and phenylephrine) increased cell size in wild-type cells, but not in IP3R1 KD cells. Our data indicate that IP3R1 mediates sustained elevation in nuclear Ca2+ level and facilitates cytosolic Ca2+ oscillation upon external ATP increase, and further suggests possible role of nuclear IP3R1 in atrial hypertrophy.
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Affiliation(s)
- Joon-Chul Kim
- Laboratory of Physiology, College of Pharmacy, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon, 34134, South Korea
| | - Min-Jeong Son
- Laboratory of Physiology, College of Pharmacy, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon, 34134, South Korea
| | - Qui Anh Le
- Laboratory of Physiology, College of Pharmacy, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon, 34134, South Korea
| | - Sun-Hee Woo
- Laboratory of Physiology, College of Pharmacy, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon, 34134, South Korea.
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18
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Wullschleger M, Blanch J, Egger M. Functional local crosstalk of inositol 1,4,5-trisphosphate receptor- and ryanodine receptor-dependent Ca2+ release in atrial cardiomyocytes. Cardiovasc Res 2017; 113:542-552. [PMID: 28158491 DOI: 10.1093/cvr/cvx020] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 01/31/2017] [Indexed: 11/12/2022] Open
Abstract
Aims Enhanced inositol 1,4,5-trisphosphate receptor (InsP3R2) expression has been associated with a variety of proarrhythmogenic cardiac disorders. The functional interaction between the two major Ca2+ release mechanisms in cardiomyocytes, Ca2+ release mediated by ryanodine receptors (RyR2s) and InsP3-induced intracellular Ca2+ release (IP3ICR) remains enigmatic. We aimed at identifying characterizing local IP3ICR events, and elucidating functional local crosstalk mechanisms between cardiac InsP3R2s and RyR2s under conditions of enhanced cardiac specific InsP3R2 activity. Methods and results Using confocal imaging and two-dimensional spark analysis, we demonstrate in atrial myocytes (mouse model cardiac specific overexpressing InsP3R2s) that local Ca2+ release through InsP3Rs (Ca2+ puff) directly activates RyRs and triggers elementary Ca2+ release events (Ca2+ sparks). In the presence of increased intracellular InsP3 concentrations IP3ICR can modulate RyRs openings and Ca2+ spark probability. We show as well that IP3ICR remains under local control of Ca2+ release through RyRs. Conclusions Our results support the concept of bidirectional interaction between RyRs and InsP3Rs (i.e. Ca2+ sparks and Ca2+ puffs) in atrial myocytes. We conclude that highly efficient InsP3 dependent SR-Ca2+ flux constitute the main mechanism of functional crosstalk between InsP3Rs and RyRs resulting in more Ca2+ sensitized RyRs to trigger subsequent Ca2+-induced Ca2+ release activation. In this way, bidirectional local interaction of both SR-Ca2+ release channels may contribute to the shaping of global Ca2+ transients and thereby to contractility in cardiac myocytes.
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MESH Headings
- Animals
- Calcium Signaling/drug effects
- Electric Stimulation
- Endothelin-1/pharmacology
- Heart Atria/metabolism
- Image Processing, Computer-Assisted
- Inositol 1,4,5-Trisphosphate/metabolism
- Inositol 1,4,5-Trisphosphate Receptors/drug effects
- Inositol 1,4,5-Trisphosphate Receptors/genetics
- Inositol 1,4,5-Trisphosphate Receptors/metabolism
- Mice, Inbred C57BL
- Mice, Transgenic
- Microscopy, Confocal
- Myocardial Contraction
- Myocytes, Cardiac/drug effects
- Myocytes, Cardiac/metabolism
- Phenotype
- Receptor Cross-Talk/drug effects
- Ryanodine Receptor Calcium Release Channel/drug effects
- Ryanodine Receptor Calcium Release Channel/metabolism
- Sarcoplasmic Reticulum/metabolism
- Time Factors
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19
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Santulli G, Nakashima R, Yuan Q, Marks AR. Intracellular calcium release channels: an update. J Physiol 2017; 595:3041-3051. [PMID: 28303572 PMCID: PMC5430224 DOI: 10.1113/jp272781] [Citation(s) in RCA: 149] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 02/20/2017] [Indexed: 12/19/2022] Open
Abstract
Ryanodine receptors (RyRs) and inositol 1,4,5-trisphosphate receptors (IP3 Rs) are calcium (Ca2+ ) release channels on the endo/sarcoplasmic reticulum (ER/SR). Here we summarize the latest advances in the field, describing the recently discovered mechanistic roles of intracellular Ca2+ release channels in the regulation of mitochondrial fitness and endothelial function, providing novel therapeutic options for the treatment of heart failure, hypertension, and diabetes mellitus.
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Affiliation(s)
- Gaetano Santulli
- The Wu Center for Molecular CardiologyColumbia UniversityNew YorkNYUSA
- Department of Physiology and Cellular BiophysicsCollege of Physicians and SurgeonsColumbia University Medical CenterNew YorkNYUSA
| | - Ryutaro Nakashima
- The Wu Center for Molecular CardiologyColumbia UniversityNew YorkNYUSA
- Department of Physiology and Cellular BiophysicsCollege of Physicians and SurgeonsColumbia University Medical CenterNew YorkNYUSA
| | - Qi Yuan
- The Wu Center for Molecular CardiologyColumbia UniversityNew YorkNYUSA
- Department of Physiology and Cellular BiophysicsCollege of Physicians and SurgeonsColumbia University Medical CenterNew YorkNYUSA
| | - Andrew R. Marks
- The Wu Center for Molecular CardiologyColumbia UniversityNew YorkNYUSA
- Department of Physiology and Cellular BiophysicsCollege of Physicians and SurgeonsColumbia University Medical CenterNew YorkNYUSA
- Department of MedicineColumbia UniversityNew YorkNYUSA
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20
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Greiser M. Calcium signalling silencing in atrial fibrillation. J Physiol 2017; 595:4009-4017. [PMID: 28332202 DOI: 10.1113/jp273045] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 01/05/2017] [Indexed: 01/19/2023] Open
Abstract
Subcellular calcium signalling silencing is a novel and distinct cellular and molecular adaptive response to rapid cardiac activation. Calcium signalling silencing develops during short-term sustained rapid atrial activation as seen clinically during paroxysmal atrial fibrillation (AF). It is the first 'anti-arrhythmic' adaptive response in the setting of AF and appears to counteract the maladaptive changes that lead to intracellular Ca2+ signalling instability and Ca2+ -based arrhythmogenicity. Calcium signalling silencing results in a failed propagation of the [Ca2+ ]i signal to the myocyte centre both in patients with AF and in a rabbit model. This adaptive mechanism leads to a substantial reduction in the expression levels of calcium release channels (ryanodine receptors, RyR2) in the sarcoplasmic reticulum, and the frequency of Ca2+ sparks and arrhythmogenic Ca2+ waves remains low. Less Ca2+ release per [Ca2+ ]i transient, increased fast Ca2+ buffering strength, shortened action potentials and reduced L-type Ca2+ current contribute to a substantial reduction of intracellular [Na+ ]. These features of Ca2+ signalling silencing are distinct and in contrast to the changes attributed to Ca2+ -based arrhythmogenicity. Some features of Ca2+ signalling silencing prevail in human AF suggesting that the Ca2+ signalling 'phenotype' in AF is a sum of Ca2+ stabilizing (Ca2+ signalling silencing) and Ca2+ destabilizing (arrhythmogenic unstable Ca2+ signalling) factors. Calcium signalling silencing is a part of the mechanisms that contribute to the natural progression of AF and may limit the role of Ca2+ -based arrhythmogenicity after the onset of AF.
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Affiliation(s)
- Maura Greiser
- Center for Biomedical Engineering and Technology and Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
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21
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Berridge MJ. The Inositol Trisphosphate/Calcium Signaling Pathway in Health and Disease. Physiol Rev 2016; 96:1261-96. [DOI: 10.1152/physrev.00006.2016] [Citation(s) in RCA: 377] [Impact Index Per Article: 47.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Many cellular functions are regulated by calcium (Ca2+) signals that are generated by different signaling pathways. One of these is the inositol 1,4,5-trisphosphate/calcium (InsP3/Ca2+) signaling pathway that operates through either primary or modulatory mechanisms. In its primary role, it generates the Ca2+ that acts directly to control processes such as metabolism, secretion, fertilization, proliferation, and smooth muscle contraction. Its modulatory role occurs in excitable cells where it modulates the primary Ca2+ signal generated by the entry of Ca2+ through voltage-operated channels that releases Ca2+ from ryanodine receptors (RYRs) on the internal stores. In carrying out this modulatory role, the InsP3/Ca2+ signaling pathway induces subtle changes in the generation and function of the voltage-dependent primary Ca2+ signal. Changes in the nature of both the primary and modulatory roles of InsP3/Ca2+ signaling are a contributory factor responsible for the onset of a large number human diseases.
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Affiliation(s)
- Michael J. Berridge
- Laboratory of Molecular Signalling, The Babraham Institute, Babraham Research Campus, Cambridge, CB22 3AT, United Kingdom
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22
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Seidlmayer LK, Kuhn J, Berbner A, Arias-Loza PA, Williams T, Kaspar M, Czolbe M, Kwong JQ, Molkentin JD, Heinze KG, Dedkova EN, Ritter O. Inositol 1,4,5-trisphosphate-mediated sarcoplasmic reticulum-mitochondrial crosstalk influences adenosine triphosphate production via mitochondrial Ca2+ uptake through the mitochondrial ryanodine receptor in cardiac myocytes. Cardiovasc Res 2016; 112:491-501. [PMID: 27496868 DOI: 10.1093/cvr/cvw185] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 06/21/2016] [Indexed: 12/22/2022] Open
Abstract
AIMS Elevated levels of inositol 1,4,5-trisphosphate (IP3) in adult cardiac myocytes are typically associated with the development of cardiac hypertrophy, arrhythmias, and heart failure. IP3 enhances intracellular Ca(2+ )release via IP3 receptors (IP3Rs) located at the sarcoplasmic reticulum (SR). We aimed to determine whether IP3-induced Ca(2+ )release affects mitochondrial function and determine the underlying mechanisms. METHODS AND RESULTS We compared the effects of IP3Rs- and ryanodine receptors (RyRs)-mediated cytosolic Ca(2+ )elevation achieved by endothelin-1 (ET-1) and isoproterenol (ISO) stimulation, respectively, on mitochondrial Ca(2+ )uptake and adenosine triphosphate (ATP) generation. Both ET-1 and isoproterenol induced an increase in mitochondrial Ca(2+ )(Ca(2 +) m) but only ET-1 led to an increase in ATP concentration. ET-1-induced effects were prevented by cell treatment with the IP3 antagonist 2-aminoethoxydiphenyl borate and absent in myocytes from transgenic mice expressing an IP3 chelating protein (IP3 sponge). Furthermore, ET-1-induced mitochondrial Ca(2+) uptake was insensitive to the mitochondrial Ca(2+ )uniporter inhibitor Ru360, however was attenuated by RyRs type 1 inhibitor dantrolene. Using real-time polymerase chain reaction, we detected the presence of all three isoforms of IP3Rs and RyRs in murine ventricular myocytes with a dominant presence of type 2 isoform for both receptors. CONCLUSIONS Stimulation of IP3Rs with ET-1 induces Ca(2+ )release from the SR which is tunnelled to mitochondria via mitochondrial RyR leading to stimulation of mitochondrial ATP production.
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Affiliation(s)
- Lea K Seidlmayer
- Department of Internal Medicine, Cardiology, University Hospital Würzburg, Oberdürrbacherstr. 6, 97080 Würzburg, Germany Comprehensive Heart Failure Center, University of Würzburg, Straubmühlweg 2a, 97078 Würzburg, Germany
| | - Johannes Kuhn
- Department of Internal Medicine, Cardiology, University Hospital Würzburg, Oberdürrbacherstr. 6, 97080 Würzburg, Germany
| | - Annette Berbner
- Department of Internal Medicine, Cardiology, University Hospital Würzburg, Oberdürrbacherstr. 6, 97080 Würzburg, Germany
| | - Paula-Anahi Arias-Loza
- Department of Internal Medicine, Cardiology, University Hospital Würzburg, Oberdürrbacherstr. 6, 97080 Würzburg, Germany
| | - Tatjana Williams
- Department of Internal Medicine, Cardiology, University Hospital Würzburg, Oberdürrbacherstr. 6, 97080 Würzburg, Germany
| | - Mathias Kaspar
- Comprehensive Heart Failure Center, University of Würzburg, Straubmühlweg 2a, 97078 Würzburg, Germany
| | - Martin Czolbe
- Department of Internal Medicine, Cardiology, University Hospital Würzburg, Oberdürrbacherstr. 6, 97080 Würzburg, Germany
| | - Jennifer Q Kwong
- Division of Molecular Cardiovascular Biology, Cincinnati Children's Hospital Medical Center, 240 Albert Sabin Way, MLC 7020 Cincinnati, OH 45229, USA
| | - Jeffery D Molkentin
- Division of Molecular Cardiovascular Biology, Cincinnati Children's Hospital Medical Center, 240 Albert Sabin Way, MLC 7020 Cincinnati, OH 45229, USA
| | - Katrin Gertrud Heinze
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Josef-Schneider-Str. 2, 97080 Würzburg, Germany
| | - Elena N Dedkova
- Department of Pharmacology, School of Medicine, University of California Davis, 451 E. Health Sciences Drive, Genome and Biomedical Sciences Facility, Davis, CA 95616, USA
| | - Oliver Ritter
- Department of Internal Medicine, Cardiology, University Hospital Würzburg, Oberdürrbacherstr. 6, 97080 Würzburg, Germany Comprehensive Heart Failure Center, University of Würzburg, Straubmühlweg 2a, 97078 Würzburg, Germany Medizinische Hochschule Brandenburg, Campus Klinikum Brandenburg/Havel, Abteilung für Kardiologie und Pneumologie, Hochstr. 29, 14770 Brandenburg an der Havel, Germany
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23
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Dedkova EN. Some Like it Hot: Cardioprotective Effect of Curcumin in Chronic Kidney Disease. Cardiovasc Drugs Ther 2015; 29:101-3. [DOI: 10.1007/s10557-015-6586-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Ju YK, Lee BH, Trajanovska S, Hao G, Allen DG, Lei M, Cannell MB. The involvement of TRPC3 channels in sinoatrial arrhythmias. Front Physiol 2015; 6:86. [PMID: 25859221 PMCID: PMC4373262 DOI: 10.3389/fphys.2015.00086] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 03/04/2015] [Indexed: 01/08/2023] Open
Abstract
Atrial fibrillation (AF) is a significant contributor to cardiovascular morbidity and mortality. The currently available treatments are limited and AF continues to be a major clinical challenge. Clinical studies have shown that AF is frequently associated with dysfunction in the sino-atrial node (SAN). The association between AF and SAN dysfunction is probably related to the communication between the SAN and the surrounding atrial cells that form the SAN-atrial pacemaker complex and/or pathological processes that affect both the SAN and atrial simultaneously. Recent evidence suggests that Ca2+ entry through TRPC3 (Transient Receptor Potential Canonical-3) channels may underlie several pathophysiological conditions -including cardiac arrhythmias. However, it is still not known if atrial and sinoatrial node cells are also involved. In this article we will first briefly review TRPC3 and IP3R signaling that relate to store/receptor-operated Ca2+ entry (SOCE/ROCE) mechanisms and cardiac arrhythmias. We will then present some of our recent research progress in this field. Our experiments results suggest that pacing-induced AF in angiotensin II (Ang II) treated mice are significantly reduced in mice lacking the TRPC3 gene (TRPC3−/− mice) compared to wild type controls. We also show that pacemaker cells express TRPC3 and several other molecular components related to SOCE/ROCE signaling, including STIM1 and IP3R. Activation of G-protein coupled receptors (GPCRs) signaling that is able to modulate SOCE/ROCE and Ang II induced Ca2+ homeostasis changes in sinoatrial complex being linked to TRPC3. The results provide new evidence that TRPC3 may play a role in sinoatrial and atrial arrhythmias that are caused by GPCRs activation.
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Affiliation(s)
- Yue-Kun Ju
- Department of Physiology, School of Medical Sciences, Bosch Institute, University of Sydney Sydney, NSW, Australia
| | - Bon Hyang Lee
- Department of Physiology, School of Medical Sciences, Bosch Institute, University of Sydney Sydney, NSW, Australia
| | - Sofie Trajanovska
- Department of Physiology, School of Medical Sciences, Bosch Institute, University of Sydney Sydney, NSW, Australia
| | - Gouliang Hao
- Department of Pharmacology, University of Oxford Oxford, UK
| | - David G Allen
- Department of Physiology, School of Medical Sciences, Bosch Institute, University of Sydney Sydney, NSW, Australia
| | - Ming Lei
- Department of Pharmacology, University of Oxford Oxford, UK
| | - Mark B Cannell
- Department of Physiology and Pharmacology, University of Bristol Bristol, UK
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Hohendanner F, Walther S, Maxwell JT, Kettlewell S, Awad S, Smith GL, Lonchyna VA, Blatter LA. Inositol-1,4,5-trisphosphate induced Ca2+ release and excitation-contraction coupling in atrial myocytes from normal and failing hearts. J Physiol 2014; 593:1459-77. [PMID: 25416623 DOI: 10.1113/jphysiol.2014.283226] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Accepted: 11/10/2014] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Impaired calcium (Ca(2+)) signalling is the main contributor to depressed ventricular contractile function and occurrence of arrhythmia in heart failure (HF). Here we report that in atrial cells of a rabbit HF model, Ca(2+) signalling is enhanced and we identified the underlying cellular mechanisms. Enhanced Ca(2+) transients (CaTs) are due to upregulation of inositol-1,4,5-trisphosphate receptor induced Ca(2+) release (IICR) and decreased mitochondrial Ca(2+) sequestration. Enhanced IICR, however, together with an increased activity of the sodium-calcium exchange mechanism, also facilitates spontaneous Ca(2+) release in form of arrhythmogenic Ca(2+) waves and spontaneous action potentials, thus enhancing the arrhythmogenic potential of atrial cells. Our data show that enhanced Ca(2+) signalling in HF provides atrial cells with a mechanism to improve ventricular filling and to maintain cardiac output, but also increases the susceptibility to develop atrial arrhythmias facilitated by spontaneous Ca(2+) release. ABSTRACT We studied excitation-contraction coupling (ECC) and inositol-1,4,5-triphosphate (IP3)-dependent Ca(2+) release in normal and heart failure (HF) rabbit atrial cells. Left ventricular HF was induced by combined volume and pressure overload. In HF atrial myocytes diastolic [Ca(2+)]i was increased, action potential (AP)-induced Ca(2+) transients (CaTs) were larger in amplitude, primarily due to enhanced Ca(2+) release from central non-junctional sarcoplasmic reticulum (SR) and centripetal propagation of activation was accelerated, whereas HF ventricular CaTs were depressed. The larger CaTs were due to enhanced IP3 receptor-induced Ca(2+) release (IICR) and reduced mitochondrial Ca(2+) buffering, consistent with a reduced mitochondrial density and Ca(2+) uptake capacity in HF. Elementary IP3 receptor-mediated Ca(2+) release events (Ca(2+) puffs) were more frequent in HF atrial myoctes and were detected more often in central regions of the non-junctional SR compared to normal cells. HF cells had an overall higher frequency of spontaneous Ca(2+) waves and a larger fraction of waves (termed arrhythmogenic Ca(2+) waves) triggered APs and global CaTs. The higher propensity of arrhythmogenic Ca(2+) waves resulted from the combined action of enhanced IICR and increased activity of sarcolemmal Na(+)-Ca(2+) exchange depolarizing the cell membrane. In conclusion, the data support the hypothesis that in atrial myocytes from hearts with left ventricular failure, enhanced CaTs during ECC exert positive inotropic effects on atrial contractility which facilitates ventricular filling and contributes to maintaining cardiac output. However, HF atrial cells were also more susceptible to developing arrhythmogenic Ca(2+) waves which might form the substrate for atrial rhythm disorders frequently encountered in HF.
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Affiliation(s)
- Felix Hohendanner
- Department of Molecular Biophysics and Physiology, Rush University Medical Center, Chicago, IL, 60612, USA
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26
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Voigt N, Dobrev D. Cellular and molecular correlates of ectopic activity in patients with atrial fibrillation. Europace 2013; 14 Suppl 5:v97-v105. [PMID: 23104921 DOI: 10.1093/europace/eus282] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Atrial fibrillation (AF) is the most frequent arrhythmia and is associated with increased morbidity and mortality. Current drugs for AF treatment have limited efficacy and a substantial risk of proarrhythmic side effects, making novel drug development critical. Emerging evidence suggests that abnormal intracellular calcium (Ca(2+)) signalling is a key contributor to ectopic (triggered) electrical activity in human AF. Accordingly, atrial Ca(2+)-handling abnormalities underlying ectopic activity may constitute novel mechanism-based therapeutic approaches to treat AF. This article reviews the recent evidence for a role of cellular ectopic activity in human AF pathophysiology, discusses the molecular mechanisms underlying triggered activity in human atrial myocytes, and considers their relevance to the design of novel therapeutic options.
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Affiliation(s)
- Niels Voigt
- Division of Experimental Cardiology, Medical Faculty Mannheim, University of Heidelberg, Theodor-Kutzer-Ufer 1-3, Mannheim, Germany
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27
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Cooley N, Ouyang K, McMullen JR, Kiriazis H, Sheikh F, Wu W, Mu Y, Du XJ, Chen J, Woodcock EA. No contribution of IP3-R(2) to disease phenotype in models of dilated cardiomyopathy or pressure overload hypertrophy. Circ Heart Fail 2012; 6:318-25. [PMID: 23258573 DOI: 10.1161/circheartfailure.112.972158] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND We investigated the contribution of inositol(1,4,5)-trisphosphate (Ins(1,4,5)P3 [IP3]) receptors (IP3-R) to disease progression in mouse models of dilated cardiomyopathy (DCM) and pressure overload hypertrophy. Mice expressing mammalian sterile 20-like kinase and dominant-negative phosphatidylinositol-3-kinase in heart (Mst1×dn-PI3K-2Tg; DCM-2Tg) develop severe DCM and conduction block, associated with increased expression of type 2 IP3-R (IP3-R(2)) and heightened generation of Ins(1,4,5)P3. Similar increases in Ins(1,4,5)P3 and IP3-R(2) are caused by transverse aortic constriction. METHODS AND RESULTS To evaluate the contribution of IP3-R(2) to disease progression, the DCM-2Tg mice were further crossed with mice in which the type 2 IP3-R (IP3-R(2)-/-) had been deleted (DCM-2Tg×IP3-R(2)-/-) and transverse aortic constriction was performed on IP3-R(2)-/- mice. Hearts from DCM-2Tg mice and DCM-2Tg×IP3-R(2)-/- were similar in terms of chamber dilatation, atrial enlargement, and ventricular wall thinning. Electrophysiological changes were also similar in the DCM-2Tg mice, with and without IP3-R(2). Deletion of IP3-R(2) did not alter the progression of heart failure, because DCM-2Tg mice with and without IP3-R(2) had similarly reduced contractility, increased lung congestion, and atrial thrombus, and both strains died between 10 and 12 weeks of age. Loss of IP3-R(2) did not alter the progression of hypertrophy after transverse aortic constriction. CONCLUSIONS We conclude that IP3-R(2) do not contribute to the progression of DCM or pressure overload hypertrophy, despite increased expression and heightened generation of the ligand, Ins(1,4,5)P3.
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Affiliation(s)
- Nicola Cooley
- Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia
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28
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Wong A, Grubb DR, Cooley N, Luo J, Woodcock EA. Regulation of autophagy in cardiomyocytes by Ins(1,4,5)P(3) and IP(3)-receptors. J Mol Cell Cardiol 2012; 54:19-24. [PMID: 23137780 DOI: 10.1016/j.yjmcc.2012.10.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Revised: 10/19/2012] [Accepted: 10/24/2012] [Indexed: 12/11/2022]
Abstract
Autophagy is a process that removes damaged proteins and organelles and is of particular importance in terminally differentiated cells such as cardiomyocytes, where it has primarily a protective role. We investigated the involvement of inositol(1,4,5)trisphosphate (Ins(1,4,5)P(3)) and its receptors in autophagic responses in neonatal rat ventricular myocytes (NRVM). Treatment with the IP(3)-receptor (IP(3)-R) antagonist 2-aminoethoxydiphenyl borate (2-APB) at 5 or 20 μmol/L resulted in an increase in autophagosome content, defined as puncta labeled by antibody to microtubule associated light chain 3 (LC3). 2-APB also increased autophagic flux, indicated by heightened LC3II accumulation, which was further enhanced by bafilomycin (10nmol/L). Expression of Ins(1,4,5)P(3) 5-phosphatase (IP(3)-5-Pase) to deplete Ins(1,4,5)P(3) also increased LC3-labeled puncta and LC3II content, suggesting that Ins(1,4,5)P(3) inhibits autophagy. The IP(3)-R can act as an inhibitory scaffold sequestering the autophagic effector, beclin-1 to its ligand binding domain (LBD). Expression of GFP-IP(3)-R-LBD inhibited autophagic signaling and furthermore, beclin-1 co-immunoprecipitated with the IP(3)-R-LBD. A mutant GFP-IP(3)-R-LBD with reduced ability to bind Ins(1,4,5)P(3) bound beclin-1 and inhibited autophagy similarly to the wild type sequence. These data provide evidence that Ins(1,4,5)P(3) and IP(3)-R act as inhibitors of autophagic responses in cardiomyocytes. By suppressing autophagy, IP(3)-R may contribute to cardiac pathology.
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Affiliation(s)
- Albert Wong
- Molecular Cardiology Laboratory, Baker IDI Heart and Diabetes Institute, 75 Commercial Road, Melbourne, Victoria 3004, Australia
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29
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Arrhythmogenic coupling between the Na+–Ca2+ exchanger and inositol 1,4,5-triphosphate receptor in rat pulmonary vein cardiomyocytes. J Mol Cell Cardiol 2012; 52:988-97. [DOI: 10.1016/j.yjmcc.2012.01.007] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Revised: 12/30/2011] [Accepted: 01/05/2012] [Indexed: 11/18/2022]
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Subedi KP, Singh TD, Kim JC, Woo SH. Cloning and expression of a new inositol 1,4,5-trisphosphate receptor type 1 splice variant in adult rat atrial myocytes. Cell Mol Biol Lett 2012; 17:124-35. [PMID: 22207335 PMCID: PMC6275638 DOI: 10.2478/s11658-011-0043-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Accepted: 12/16/2011] [Indexed: 11/20/2022] Open
Abstract
Inositol 1,4,5-trisphosphate receptor type 1 (IP(3)R1) is already known to be highly expressed in the brain, and is found in many other tissues, including the atrium of the heart. Although the complete primary structure of IP(3)R1 in the rat brain has been reported, the complete sequence of an IP(3)R1 clone from atrial myocytes has not been reported. We isolated an IP(3)R1 complementary DNA (cDNA) clone from isolated adult rat atrial myocytes, and found a new splice variant of IP(3)R1 that was different from a previously reported IP(3)R1 cDNA clone obtained from a rat brain (NCBI GenBank accession number: NM_001007235). Our clone had 99% similarity with the rat brain IP(3)R1 sequence; the exceptions were 39 amino acid deletions at the position of 1693-1731, and the deletion of phenylalanine at position 1372 that lay in the regulatory region. Compared with the rat brain IP(3)R1, in our clone proline was replaced with serine at residue 2439, and alanine was substituted for valine at residue 2445. These changes lie adjacent to or within the fifth transmembrane domain (2440-2462). Although such changes in the amino acid sequences were different from the rat brain IP3R1 clone, they were conserved in human or mouse IP3R1. We produced a plasmid construct expressing the atrial IP3R1 together with green fluorescent protein (GFP), and successfully overexpressed the atrial IP3R1 in the adult atrial cell line HL-1. Further investigation is needed on the physiological significance of the new splice variant in atrial cell function.
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Affiliation(s)
- Krishna P. Subedi
- College of Pharmacy, IDRD, Chungnam National University, 220 Gung-dong, Yuseong-gu, Daejeon, 305-764 South Korea
| | - Thoudam Debraj Singh
- College of Pharmacy, IDRD, Chungnam National University, 220 Gung-dong, Yuseong-gu, Daejeon, 305-764 South Korea
| | - Joon-Chul Kim
- College of Pharmacy, IDRD, Chungnam National University, 220 Gung-dong, Yuseong-gu, Daejeon, 305-764 South Korea
| | - Sun-Hee Woo
- College of Pharmacy, IDRD, Chungnam National University, 220 Gung-dong, Yuseong-gu, Daejeon, 305-764 South Korea
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Voigt N, Nattel S, Dobrev D. Proarrhythmic atrial calcium cycling in the diseased heart. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 740:1175-91. [PMID: 22453988 DOI: 10.1007/978-94-007-2888-2_53] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
During the last decades Ca(2+) has been found to play a crucial role in cardiac arrhythmias associated with heart failure and a number of congenital arrhythmia syndromes. Recent studies demonstrated that altered atrial Ca(2+) cycling may promote the initiation and maintenance of atrial fibrillation, the most common clinical arrhythmia that contributes significantly to population morbidity and mortality. This article describes physiological Ca(2+) cycling mechanisms in atrial cardiomyocytes and relates them to fundamental cellular proarrhythmic mechanisms involving Ca(2+) signaling abnormalities in the atrium during atrial fibrillation.
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Affiliation(s)
- Niels Voigt
- Division of Experimental Cardiology, Medical Faculty Mannheim, University of Heidelberg, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany.
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Llach A, Molina CE, Prat-Vidal C, Fernandes J, Casado V, Ciruela F, Lluis C, Franco R, Cinca J, Hove-Madsen L. Abnormal calcium handling in atrial fibrillation is linked to up-regulation of adenosine A2A receptors. Eur Heart J 2010; 32:721-9. [DOI: 10.1093/eurheartj/ehq464] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Greiser M, Lederer WJ, Schotten U. Alterations of atrial Ca(2+) handling as cause and consequence of atrial fibrillation. Cardiovasc Res 2010; 89:722-33. [PMID: 21159669 DOI: 10.1093/cvr/cvq389] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Atrial fibrillation (AF) is the most prevalent sustained arrhythmia. As the most important risk factor for embolic stroke, AF is associated with a high morbidity and mortality. Despite decades of research, successful (pharmacological and interventional) 'ablation' of the arrhythmia remains challenging. AF is characterized by a diverse aetiology, including heart failure, hypertension, and valvular disease. Based on this understanding, new treatment strategies that are specifically tailored to the underlying pathophysiology of a certain 'type' of AF are being developed. One important aspect of AF pathophysiology is altered intracellular Ca(2+) handling. Due to the increase in the atrial activation rate and the subsequent initial [Ca(2+)](i) overload, AF induces 'remodelling' of intracellular Ca(2+) handling. Current research focuses on unravelling the contribution of altered intracellular Ca(2+) handling to different types of AF. More specifically, changes in intracellular Ca(2+) homeostasis preceding the onset of AF, in conditions which predispose to AF (e.g. heart failure), appear to be different from changes in Ca(2+) handling developing after the onset of AF. Here we review and critique altered intracellular Ca(2+) handling and its contribution to three specific aspects of AF pathophysiology, (i) excitation-transcription coupling and Ca(2+)-dependent signalling pathways, (ii) atrial contractile dysfunction, and (iii) arrhythmogenicity.
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Affiliation(s)
- Maura Greiser
- Department of Physiology, Maastricht University, Maastricht, The Netherlands
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Atrial local Ca2+ signaling and inositol 1,4,5-trisphosphate receptors. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2010; 103:59-70. [DOI: 10.1016/j.pbiomolbio.2010.02.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2009] [Revised: 01/18/2010] [Accepted: 02/18/2010] [Indexed: 11/24/2022]
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Xiao J, Liang D, Zhao H, Liu Y, Zhang H, Lu X, Liu Y, Li J, Peng L, Chen YH. 2-Aminoethoxydiphenyl borate, a inositol 1,4,5-triphosphate receptor inhibitor, prevents atrial fibrillation. Exp Biol Med (Maywood) 2010; 235:862-8. [PMID: 20472714 DOI: 10.1258/ebm.2010.009362] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The expression of the inositol 1,4,5-triphosphate receptor (IP3R) is upregulated and the function of IP3R also increases during atrial fibrillation (AF). 2-Aminoethoxydiphenyl borate (2-APB) is a membrane-permeable inhibitor of IP3R. However, the effect of 2-APB on AF is unknown. The aim of the present study is to explore the effects of 2-APB on AF. In vitro rabbit heart models of ischemia-, stretch- and cholinergic agitation-induced AF were developed. Fura-2-acetoxymethyl (Fura-2-AM) and Mg2+-Fura-2-AM were used to monitor alterations of intracellular Ca2+ and ATP, respectively, in HL-1 cells, an atrial muscle cell line, under chemical ischemia or cholinergic agitation. The results showed that inhibition of IP3R significantly reduced the incidence and its probability of being sustained in all three types of AF. IP3R inhibition ameliorated the cytoplasmic Ca2+ overload and energy compromise resulting from chemical ischemia or cholinergic agitation. Thus, IP3R inhibition may be a novel target for AF treatment, and IP3R may be an important molecule in the context of different kinds of AF.
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Affiliation(s)
- Junjie Xiao
- Department of Cardiology, Tongji Hospital, Tongji University School of Medicine, Tongji University, 389 Xin Cun Road, Shanghai, China
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Wehrens XHT, Ather S, Dobrev D. Role of abnormal sarcoplasmic reticulum function in atrial fibrillation. ACTA ACUST UNITED AC 2010. [DOI: 10.2217/thy.10.8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Increased InsP3Rs in the junctional sarcoplasmic reticulum augment Ca2+ transients and arrhythmias associated with cardiac hypertrophy. Proc Natl Acad Sci U S A 2009; 106:11406-11. [PMID: 19549843 DOI: 10.1073/pnas.0905485106] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cardiac hypertrophy is a growth response of the heart to increased hemodynamic demand or damage. Accompanying this heart enlargement is a remodeling of Ca(2+) signaling. Due to its fundamental role in controlling cardiomyocyte contraction during every heartbeat, modifications in Ca(2+) fluxes significantly impact on cardiac output and facilitate the development of arrhythmias. Using cardiomyocytes from spontaneously hypertensive rats (SHRs), we demonstrate that an increase in Ca(2+) release through inositol 1,4,5-trisphosphate receptors (InsP(3)Rs) contributes to the larger excitation contraction coupling (ECC)-mediated Ca(2+) transients characteristic of hypertrophic myocytes and underlies the more potent enhancement of ECC-mediated Ca(2+) transients and contraction elicited by InsP(3) or endothelin-1 (ET-1). Responsible for this is an increase in InsP(3)R expression in the junctional sarcoplasmic reticulum. Due to their close proximity to ryanodine receptors (RyRs) in this region, enhanced Ca(2+) release through InsP(3)Rs served to sensitize RyRs, thereby increasing diastolic Ca(2+) levels, the incidence of extra-systolic Ca(2+) transients, and the induction of ECC-mediated Ca(2+) elevations. Unlike the increase in InsP(3)R expression and Ca(2+) transient amplitude in the cytosol, InsP(3)R expression and ECC-mediated Ca(2+) transients in the nucleus were not altered during hypertrophy. Elevated InsP(3)R2 expression was also detected in hearts from human patients with heart failure after ischemic dilated cardiomyopathy, as well as in aortic-banded hypertrophic mouse hearts. Our data establish that increased InsP(3)R expression is a general mechanism that underlies remodeling of Ca(2+) signaling during heart disease, and in particular, in triggering ventricular arrhythmia during hypertrophy.
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Huang CX, Liu Y, Xia WF, Tang YH, Huang H. Oxidative stress: a possible pathogenesis of atrial fibrillation. Med Hypotheses 2008; 72:466-7. [PMID: 19103473 DOI: 10.1016/j.mehy.2008.08.031] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2008] [Revised: 08/04/2008] [Accepted: 08/18/2008] [Indexed: 11/17/2022]
Abstract
Atrial fibrillation (AF) is the most commonly sustained arrhythmia in clinical practice. Despite the extensive studies, the pathophysiology of AF, however, remains incompletely understood. Studies have demonstrated that oxidative stress may be involved in cardiac structural and electrical remodeling. More recently, a growing body of evidence suggests that oxidative stress is associated with the development of AF. The evidence for the hypotheses included that: (1) histological studies have demonstrated oxidative damage in both AF patients and animal models of AF; (2) oxidative stress markers are increased in AF patients, and are associated with the presence of AF; (3) drugs that have antioxidant properties show beneficial effects on AF development. Although the studies suggest the association between oxidative stress and AF, the exact pathogenesis of oxidative stress in AF development remains elusive and requires further investigation. Specifically, the causality between oxidative stress and AF; the levels of the oxidative stress in various types of AFs and their role in the pathogenesis of AF; the effects of strategies to reduce oxidative stress on atrial structural and electrical remodeling, and their exact role in the development of AF. Oxidative stress may provide a scientific basis for further research on the underlying mechanisms of AF and may target for pharmacological interruption of AF.
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Affiliation(s)
- Cong-Xin Huang
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan 430060, PR China.
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39
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Abstract
The calcium ion (Ca(2+)) is the simplest and most versatile intracellular messenger known. The discovery of Ca(2+) sparks and a related family of elementary Ca(2+) signaling events has revealed fundamental principles of the Ca(2+) signaling system. A newly appreciated "digital" subsystem consisting of brief, high Ca(2+) concentration over short distances (nanometers to microns) comingles with an "analog" global Ca(2+) signaling subsystem. Over the past 15 years, much has been learned about the theoretical and practical aspects of spark formation and detection. The quest for the spark mechanisms [the activation, coordination, and termination of Ca(2+) release units (CRUs)] has met unexpected challenges, however, and raised vexing questions about CRU operation in situ. Ample evidence shows that Ca(2+) sparks catalyze many high-threshold Ca(2+) processes involved in cardiac and skeletal muscle excitation-contraction coupling, vascular tone regulation, membrane excitability, and neuronal secretion. Investigation of Ca(2+) sparks in diseases has also begun to provide novel insights into hypertension, cardiac arrhythmias, heart failure, and muscular dystrophy. An emerging view is that spatially and temporally patterned activation of the digital subsystem confers on intracellular Ca(2+) signaling an exquisite architecture in space, time, and intensity, which underpins signaling efficiency, stability, specificity, and diversity. These recent advances in "sparkology" thus promise to unify the simplicity and complexity of Ca(2+) signaling in biology.
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Affiliation(s)
- Heping Cheng
- Institute of Molecular Medicine, National Laboratory of Biomembrane and Membrane Biotechnology, Peking University, Beijing, China.
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40
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Abstract
Arrhythmias arise from a complex interaction between structural changes in the myocardium and changes in cellular electrophysiology. Electrophysiological balance requires precise control of sarcolemmal ion channels and exchangers, many of which are regulated by phospholipid, phosphatidylinositol(4,5)bisphosphate. Phosphatidylinositol(4,5)bisphosphate is the immediate precursor of inositol(1,4,5)trisphosphate, a regulator of intracellular Ca2+ signalling and, therefore, a potential contributor to arrhythmogenesis by altering Ca2+ homeostasis. The aim of the present review is to outline current evidence that this signalling pathway can be a player in the initiation or maintenance of arrhythmias.
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Affiliation(s)
- Elizabeth A Woodcock
- Molecular Cardiology Laboratory, Baker IDI Heart and Diabetes Institute, PO Box 6492, St Kilda Road Central, Melbourne, 8008 Victoria, Australia.
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41
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Kockskämper J, Zima AV, Roderick HL, Pieske B, Blatter LA, Bootman MD. Emerging roles of inositol 1,4,5-trisphosphate signaling in cardiac myocytes. J Mol Cell Cardiol 2008; 45:128-47. [PMID: 18603259 PMCID: PMC2654363 DOI: 10.1016/j.yjmcc.2008.05.014] [Citation(s) in RCA: 142] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2008] [Revised: 05/20/2008] [Accepted: 05/21/2008] [Indexed: 01/19/2023]
Abstract
Inositol 1,4,5-trisphosphate (IP(3)) is a ubiquitous intracellular messenger regulating diverse functions in almost all mammalian cell types. It is generated by membrane receptors that couple to phospholipase C (PLC), an enzyme which liberates IP(3) from phosphatidylinositol 4,5-bisphosphate (PIP(2)). The major action of IP(3), which is hydrophilic and thus translocates from the membrane into the cytoplasm, is to induce Ca(2+) release from endogenous stores through IP(3) receptors (IP(3)Rs). Cardiac excitation-contraction coupling relies largely on ryanodine receptor (RyR)-induced Ca(2+) release from the sarcoplasmic reticulum. Myocytes express a significantly larger number of RyRs compared to IP(3)Rs (~100:1), and furthermore they experience substantial fluxes of Ca(2+) with each heartbeat. Therefore, the role of IP(3) and IP(3)-mediated Ca(2+) signaling in cardiac myocytes has long been enigmatic. Recent evidence, however, indicates that despite their paucity cardiac IP(3)Rs may play crucial roles in regulating diverse cardiac functions. Strategic localization of IP(3)Rs in cytoplasmic compartments and the nucleus enables them to participate in subsarcolemmal, bulk cytoplasmic and nuclear Ca(2+) signaling in embryonic stem cell-derived and neonatal cardiomyocytes, and in adult cardiac myocytes from the atria and ventricles. Intriguingly, expression of both IP(3)Rs and membrane receptors that couple to PLC/IP(3) signaling is altered in cardiac disease such as atrial fibrillation or heart failure, suggesting the involvement of IP(3) signaling in the pathology of these diseases. Thus, IP(3) exerts important physiological and pathological functions in the heart, ranging from the regulation of pacemaking, excitation-contraction and excitation-transcription coupling to the initiation and/or progression of arrhythmias, hypertrophy and heart failure.
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Affiliation(s)
- Jens Kockskämper
- Division of Cardiology, Medical University of Graz,, Auenbruggerplatz 15, A-8036 Graz, Austria
| | - Aleksey V. Zima
- Department of Molecular Biophysics & Physiology, Rush University, 1750 W. Harrison St., Chicago, IL 60612, USA
| | - H. Llewelyn Roderick
- Laboratory of Molecular Signalling, Babraham Institute, Cambridge CB2 4AT, UK
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1 PD, UK
| | - Burkert Pieske
- Division of Cardiology, Medical University of Graz,, Auenbruggerplatz 15, A-8036 Graz, Austria
| | - Lothar A. Blatter
- Department of Molecular Biophysics & Physiology, Rush University, 1750 W. Harrison St., Chicago, IL 60612, USA
| | - Martin D. Bootman
- Laboratory of Molecular Signalling, Babraham Institute, Cambridge CB2 4AT, UK
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Suzuki S, Ohkusa T, Ono K, Sato T, Yoshida MA, Yano M, Takebayashi S, Matsuzaki M. Beneficial effects of the dual L- and T-type Ca2+ channel blocker efonidipine on cardiomyopathic hamsters. Circ J 2008; 71:1970-6. [PMID: 18037756 DOI: 10.1253/circj.71.1970] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND The T-type Ca2+ channel (TCC) is activated, and abnormalities of the TCC may be related to the pathogenesis of Ca2+ overload, in cardiomyopathic hamster hearts. The aims of the present study were to investigate the alteration in expression of the TCC and to examine the effects of a dual L-and T-type Ca2+ channel blocker, efonidipine (EFO), on cardiac function and TCC during development of heart failure in UM-X7.1 cardiomyopathic hamsters. METHODS AND RESULTS UM-X7.1 and golden hamsters were examined, and EFO was administered at the age of 20 weeks for 4 weeks. Cardiac function was examined, the expression of TCCalpha1G was measured, and ventricular myocytes were subjected to a patch-clamp study. At 24 weeks, vehicle-treated UM-X7.1 hamsters exhibited significant increases in left ventricular (LV) size, with marked decreases in ejection fraction (LVEF) compared with golden hamsters. In the UM-X7.1 group, the expression of TCCalpha1G increased during development of heart failure compared with the golden hamster group. In the UM-X7.1 group, EFO treatment significantly attenuated the decrease of LVEF without affecting blood pressure compared with the vehicle group. EFO treatment decreased heart rate (by approximately 10%) in both groups. In the golden hamster group, EFO treatment did not affect LV function. The TCC current in ventricular myocytes was significantly increased in UM-X7.1, and was inhibited by EFO in a dose-dependent manner. CONCLUSIONS In cardiomyopathic hamster hearts, abnormalities in the TCC may be at least in part related to the pathogenesis of abnormal Ca2+ homeostasis, and TCC-blocker treatment may decrease the TCC current, resulting in an improvement of cardiac function. TCC blocker therapy might be a new strategy for certain types of heart failure.
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Affiliation(s)
- Shinsuke Suzuki
- Division of Cardiology, Department of Medicine and Clinical Science, Yamaguchi University Graduate School of Medicine, Ube, Japan
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43
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Luo D, Yang D, Lan X, Li K, Li X, Chen J, Zhang Y, Xiao RP, Han Q, Cheng H. Nuclear Ca2+ sparks and waves mediated by inositol 1,4,5-trisphosphate receptors in neonatal rat cardiomyocytes. Cell Calcium 2008; 43:165-74. [PMID: 17583790 PMCID: PMC2266086 DOI: 10.1016/j.ceca.2007.04.017] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2007] [Revised: 04/16/2007] [Accepted: 04/29/2007] [Indexed: 11/21/2022]
Abstract
Dynamic nuclear Ca(2+) signals play pivotal roles in diverse cellular functions including gene transcription, cell growth, differentiation, and apoptosis. Here we report a novel nuclear Ca(2+) regulatory mechanism mediated by inositol 1,4,5-trisphosphate receptors (IP(3)Rs) around the nucleus in developing cardiac myocytes. Activation of IP(3)Rs by alpha(1)-adrenergic receptor (alpha(1)AR) stimulation or by IP(3) application (in saponin-permeabilized cells) increases Ca(2+) spark frequency preferentially in the region around the nucleus in neonatal rat ventricular myocytes. A nuclear enrichment of IP(3)R distribution supports the higher responsiveness of Ca(2+) release in this particular region. Strikingly, we observed "nuclear Ca(2+)waves" that engulf the entire nucleus without spreading into the bulk cytosol. alpha(1)AR stimulation enhances the occurrence of nuclear Ca(2+) waves and confers them the ability to trigger cytosolic Ca(2+) waves via IP(3)R-dependent pathways. This finding accounts, at least partly, for a profound frequency-dependent modulation of global Ca(2+) oscillations during alpha(1)AR stimulation. Thus, IP(3)R-mediated Ca(2+) waves traveling in the nuclear region provide active, autonomous regulation of nuclear Ca(2+) signaling, which provides for not only the local signal transduction, but also a pacemaker to drive global Ca(2+) transient in the context of alpha(1)AR stimulation in developing cardiac myocytes.
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MESH Headings
- Adrenergic alpha-Agonists/pharmacology
- Animals
- Animals, Newborn
- Calcium Signaling/physiology
- Cell Membrane Permeability
- Inositol 1,4,5-Trisphosphate Receptors/drug effects
- Inositol 1,4,5-Trisphosphate Receptors/physiology
- Microscopy, Confocal
- Myocytes, Cardiac/physiology
- Nuclear Envelope/physiology
- Phenylephrine/pharmacology
- Rats
- Rats, Sprague-Dawley
- Receptors, Adrenergic, alpha-1/drug effects
- Receptors, Adrenergic, alpha-1/physiology
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Affiliation(s)
- Dali Luo
- Department of Pharmacology, School of Chemical Biology & Pharmaceutical Sciences, Capital Medical University, Beijing 100069, China.
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44
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Bootman MD, Roderick HL. Why, where, and when do cardiac myocytes express inositol 1,4,5-trisphosphate receptors? Am J Physiol Heart Circ Physiol 2008; 294:H579-81. [PMID: 18065525 DOI: 10.1152/ajpheart.01378.2007] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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45
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Amirahmadi F, Turnbull L, Du XJ, Graham RM, Woodcock EA. Heightened alpha1A-adrenergic receptor activity suppresses ischaemia/reperfusion-induced Ins(1,4,5)P3 generation in the mouse heart: a comparison with ischaemic preconditioning. Clin Sci (Lond) 2008; 114:157-64. [PMID: 17696883 DOI: 10.1042/cs20070110] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Reperfusion of ischaemic rat or mouse hearts causes NE [noradrenaline ('norepinephrine')] release, stimulation of alpha(1)-ARs (alpha(1)-adrenergic receptors), PLC (phospholipase C) activation, Ins(1,4,5)P(3) generation and the development of arrhythmias. In the present study, we examined the effect of increased alpha(1A)-AR drive on these responses. In hearts from non-transgenic mice (alpha(1A)-WT), Ins(1,4,5)P(3) generation was observed after 2 min of reperfusion following 30 min of zero-flow ischaemia. No Ins(1,4,5)P(3) response was observed in hearts from transgenic mice with 66-fold overexpression of alpha(1A)-AR (alpha(1A)-TG). This was despite the fact that alpha(1A)-TG hearts had 8-10-fold higher PLC responses to NE than alpha(1A)-WT under normoxic conditions. The immediate phospholipid precursor of Ins(1,4,5)P(3), PtdIns(4,5)P(2), responded to ischaemia and reperfusion similarly in alpha(1A)-WT and alpha(1A)-TG mice. Thus the lack of Ins(1,4,5)P(3) generation in alpha(1A)-TG mice is not caused by limited availability of PtdIns(4,5)P(2). Overall, alpha(1)-AR-mediated PLC activity was markedly enhanced in alpha(1A)-WT mice under reperfusion conditions, but responses in alpha(1A)-TG mice were not significantly different in normoxia and post-ischaemic reperfusion. Ischaemic preconditioning prevented Ins(1,4,5)P(3) generation after 30 min of ischaemic insult in alpha(1A)-WT mice. However, the precursor lipid PtdIns(4,5)P(2) was also reduced by preconditioning, whereas heightened alpha(1A)-AR activity did not influence PtdIns(4,5)P(2) responses in reperfusion. Thus preconditioning and alpha(1A)-AR overexpression have different effects on early signalling responses, even though both prevented Ins(1,4,5)P(3) generation. These studies demonstrate a selective inhibitory action of heightened alpha(1A)-AR activity on immediate post-receptor signalling responses in early post-ischaemic reperfusion.
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Affiliation(s)
- Fatemeh Amirahmadi
- Cellular Biochemistry Laboratory, Baker Heart Research Institute, PO Box 6492, St. Kilda Road Central, Melbourne, VIC 8008, Australia
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Kockskämper J, Seidlmayer L, Walther S, Hellenkamp K, Maier LS, Pieske B. Endothelin-1 enhances nuclear Ca2+ transients in atrial myocytes through Ins(1,4,5)P3-dependent Ca2+ release from perinuclear Ca2+ stores. J Cell Sci 2007; 121:186-95. [PMID: 18089647 DOI: 10.1242/jcs.021386] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Nuclear Ca2+ plays a key role in the regulation of gene expression. Inositol (1,4,5)-trisphosphate [Ins(1,4,5)P3)] might be an important regulator of nuclear Ca2+ but its contribution to nuclear Ca2+ signalling in adult cardiomyocytes remains elusive. We tested the hypothesis that endothelin-1 enhances nuclear Ca2+ concentration transients (CaTs) in rabbit atrial myocytes through Ins(1,4,5)P3-induced Ca(2+) release from perinuclear stores. Cytoplasmic and nuclear CaTs were measured simultaneously in electrically stimulated atrial myocytes using confocal Ca2+ imaging. Nuclear CaTs were significantly slower than cytoplasmic CaTs, indicative of compartmentalisation of intracellular Ca2+ signalling. Endothelin-1 elicited a preferential (10 nM) or a selective (0.1 nM) increase in nuclear versus cytoplasmic CaTs. This effect was abolished by inhibition of endothelin-1 receptors, phospholipase C and Ins(1,4,5)P3 receptors. Fractional Ca2+ release from the sarcoplasmic reticulum and perinuclear stores was increased by endothelin-1 at an otherwise unaltered Ca2+ load. Comparable increases of cytoplasmic CaTs induced by beta-adrenoceptor stimulation or elevation of extracellular Ca2+ could not mimic the endothelin-1 effects on nuclear CaTs, suggesting that endothelin-1 specifically modulates nuclear Ca2+ signalling. Thus, endothelin-1 enhances nuclear CaTs in atrial myocytes by increasing fractional Ca2+ release from perinuclear stores. This effect is mediated by the coupling of endothelin receptor A to PLC-Ins(1,4,5)P3 signalling and might contribute to excitation-transcription coupling.
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Affiliation(s)
- Jens Kockskämper
- Department of Cardiology and Pneumology, University Medicine Göttingen, Germany.
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47
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Lezoualc'h F, Steplewski K, Sartiani L, Mugelli A, Fischmeister R, Bril A. Quantitative mRNA analysis of serotonin 5-HT4 receptor isoforms, calcium handling proteins and ion channels in human atrial fibrillation. Biochem Biophys Res Commun 2007; 357:218-24. [PMID: 17418812 DOI: 10.1016/j.bbrc.2007.03.124] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2007] [Accepted: 03/20/2007] [Indexed: 11/30/2022]
Abstract
Serotonin 5-HT(4) receptors are present in human atrial myocytes and have been proposed to contribute to the generation of atrial fibrillation (AF). Here, we quantified 5-HT(4) receptors as well as other key genes involved in cardiac rhythm and contraction in right atrial appendages of patients with chronic AF (CAF) and acute AF (AAF). Right atrial appendages were obtained from eleven patients in sinus rhythm (SR), five with AAF and six with CAF (>12 months). TaqMan real time quantitative RT-PCR was performed on total RNA. Results were normalised to the average of three housekeeping genes, cyclophilin, GADPH and RL-19. The rank order of expression of h5-HT(4) receptors variants was (b)>(a)>(g)>(c) in the group of patients in SR. In AAF, we found a strong decrease in h5-HT(4(b)), h5-HT(4(c),) and h5-HT(4(g)) transcripts. In CAF patients, the mRNA expression level of the h5-HT(4(b)) isoform significantly increased two fold versus SR. A similar increase was reported for beta(1)-adrenergic receptor, connexin 43 and the L-type Ca(2+) channel CaCNA1C subunit. Interestingly, CAF was associated with a strong increase in the expression of Na(+)/Ca(2+) exchanger and the voltage-dependent Na(+) channel SCN5A subunit. Our results indicate that h5-HT(4(b)) is the dominant cardiac isoform of human 5-HT(4) receptors and its expression is increased in CAF. These data support the involvement of 5-HT(4) receptors in atrial arrhythmia.
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48
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Abstract
The inositol 1,4,5-trisphosphate (InsP3) receptors (InsP3Rs) are a family of Ca2+ release channels localized predominately in the endoplasmic reticulum of all cell types. They function to release Ca2+ into the cytoplasm in response to InsP3 produced by diverse stimuli, generating complex local and global Ca2+ signals that regulate numerous cell physiological processes ranging from gene transcription to secretion to learning and memory. The InsP3R is a calcium-selective cation channel whose gating is regulated not only by InsP3, but by other ligands as well, in particular cytoplasmic Ca2+. Over the last decade, detailed quantitative studies of InsP3R channel function and its regulation by ligands and interacting proteins have provided new insights into a remarkable richness of channel regulation and of the structural aspects that underlie signal transduction and permeation. Here, we focus on these developments and review and synthesize the literature regarding the structure and single-channel properties of the InsP3R.
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Affiliation(s)
- J Kevin Foskett
- Department of Physiology, University of Pennsylvania, Philadelphia 19104-6085, USA.
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49
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Zhao ZH, Zhang HC, Xu Y, Zhang P, Li XB, Liu YS, Guo JH. Inositol-1,4,5-Trisphosphate and Ryanodine-Dependent Ca 2+ Signaling in a Chronic Dog Model of Atrial Fibrillation. Cardiology 2006; 107:269-76. [PMID: 16954684 DOI: 10.1159/000095517] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2006] [Accepted: 06/12/2006] [Indexed: 01/21/2023]
Abstract
Ca2+ signaling regulation plays an important role in triggering and/or maintaining atrial fibrillation (AF). Little is known about the relationship of the inositol-1,4,5-triphosphate receptors (InsP3Rs) and ryanodine receptors (RyRs) in left atrium to chronic AF. In this study, we investigated the expression and function of InsP3R1, InsP3R2 and RyR2 in a chronic dog model of AF. AF was induced in 6 dogs by rapid right atrial pacing for 24 weeks, and a sham procedure was performed in 5 dogs (control group). The intact left atrial myocytes were used to examine the expression and function of InsP3Rs, RyRs by BODIPY(O,R) TR-X ryanodine, heparin-fluorescein conjugate, and were stimulated by caffeine, ATP to release Ca2+ through RyRs, InsP3Rs separately. We also assessed the molecular components of left atrial tissue underlying the amount of RyR2, InsP3R1 and InsP3R2 determined by RT-PCR, immunohistochemistry and Western blot analysis. In the chronic AF group, the Ca2+ released through RyRs is not altered, but the Ca2+ released through InsP3Rs increased significantly. RyR2 distributed in cytosol of myocytes, cellular membrane; its expression significantly decreased in AF group compared to controls. InsP3R1 distributed in cytosol, InsP3R2 distributed not only in cytosol, cellular membrane, but also in nuclear envelope and intercalated discs. The InsP3R1 and InsP3R2 expression significantly increased in chronic AF group compared to controls. These results indicated that in a chronic dog model of AF, the expression and function of RyR2 down-regulated; on the contrary, the expression and function of InsP3R1, InsP3R2 up-regulated, and InsP3R2 may be the major InsP3Rs, which regulate intracellular or even intercellular Ca2+ signal transmission.
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Affiliation(s)
- Zhi-Hong Zhao
- Electrophysiology Group, Department of Cardiology, People's Hospital, Peking University, Beijing, China.
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50
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Proven A, Roderick HL, Conway SJ, Berridge MJ, Horton JK, Capper SJ, Bootman MD. Inositol 1,4,5-trisphosphate supports the arrhythmogenic action of endothelin-1 on ventricular cardiac myocytes. J Cell Sci 2006; 119:3363-75. [PMID: 16882691 DOI: 10.1242/jcs.03073] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Although ventricular cardiomyocytes express inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] receptors, it is unclear how these Ca2+ channels contribute to the effects of Gq-coupled agonists. Endothelin-1 augmented the amplitude of pacing-evoked Ca2+ signals (positive inotropy), and caused an increasing frequency of spontaneous diastolic Ca2+-release transients. Both effects of endothelin-1 were blocked by an antagonist of phospholipase C, suggesting that Ins(1,4,5)P3 and/or diacylglycerol production was necessary. The endothelin-1-mediated spontaneous Ca2+ transients were abolished by application of 2-aminoethoxydiphenyl borate (2-APB), an antagonist of Ins(1,4,5)P3 receptors. Incubation of electrically-paced ventricular myocytes with a membrane-permeant Ins(1,4,5)P3 ester provoked the occurrence of spontaneous diastolic Ca2+ transients with the same characteristics and sensitivity to 2-APB as the events stimulated by endothelin-1. In addition to evoking spontaneous Ca2+ transients, stimulation of ventricular myocytes with the Ins(1,4,5)P3 ester caused a positive inotropic effect. The effects of endothelin-1 were compared with two other stimuli, isoproterenol and digoxin, which are known to induce inotropy and spontaneous Ca2+ transients by overloading intracellular Ca2+ stores. The events evoked by isoproterenol and digoxin were dissimilar from those triggered by endothelin-1 in several ways. We propose that Ins(1,4,5)P3 receptors support the development of both inotropy and spontaneous pro-arrhythmic Ca2+ signals in ventricular myocytes stimulated with a Gq-coupled agonist.
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MESH Headings
- Animals
- Arrhythmias, Cardiac/etiology
- Arrhythmias, Cardiac/metabolism
- Boron Compounds/pharmacology
- Calcium/metabolism
- Calcium Channels/metabolism
- Calcium Signaling
- Digoxin/pharmacology
- Endothelin-1/pharmacology
- Heart Ventricles/drug effects
- Heart Ventricles/metabolism
- Inositol 1,4,5-Trisphosphate/metabolism
- Inositol 1,4,5-Trisphosphate Receptors
- Isoproterenol/pharmacology
- Myocytes, Cardiac/drug effects
- Myocytes, Cardiac/metabolism
- Rats
- Rats, Wistar
- Receptors, Cytoplasmic and Nuclear/metabolism
- Type C Phospholipases/pharmacology
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Affiliation(s)
- Andrew Proven
- Calcium Group, Laboratory of Molecular Signalling, Babraham Institute, Babraham, Cambridge, CB2 4AT, UK
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