1
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Koga D, Kusumi S, Yagi H, Kato K. Three-dimensional analysis of the intracellular architecture by scanning electron microscopy. Microscopy (Oxf) 2024; 73:215-225. [PMID: 37930813 DOI: 10.1093/jmicro/dfad050] [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: 06/19/2023] [Revised: 10/05/2023] [Accepted: 10/27/2023] [Indexed: 11/08/2023] Open
Abstract
The two-dimensional observation of ultrathin sections from resin-embedded specimens provides an insufficient understanding of the three-dimensional (3D) morphological information of membranous organelles. The osmium maceration method, developed by Professor Tanaka's group >40 years ago, is the only technique that allows direct observation of the 3D ultrastructure of membrane systems using scanning electron microscopy (SEM), without the need for any reconstruction process. With this method, the soluble cytoplasmic proteins are removed from the freeze-cracked surface of cells while preserving the integrity of membranous organelles, achieved by immersing tissues in a diluted osmium solution for several days. By employing the maceration method, researchers using SEM have revealed the 3D ultrastructure of organelles such as the Golgi apparatus, mitochondria and endoplasmic reticulum in various cell types. Recently, we have developed new SEM techniques based on the maceration method to explore further possibilities of this method. These include: (i) a rapid osmium maceration method that reduces the reaction duration of the procedure, (ii) a combination method that combines agarose embedding with osmium maceration to elucidate the 3D ultrastructure of organelles in free and cultured cells and (iii) a correlative immunofluorescence and SEM technique that combines cryosectioning with the osmium maceration method, enabling the correlation of the immunocytochemical localization of molecules with the 3D ultrastructure of organelles. In this paper, we review the novel osmium maceration methods described earlier and discuss their potential and future directions in the field of biology and biomedical research.
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Affiliation(s)
- Daisuke Koga
- Department of Microscopic Anatomy and Cell Biology, Asahikawa Medical University, 2-1-1-1 Midorigaoka-higashi, Asahikawa 078-8510, Japan
| | - Satoshi Kusumi
- Division of Morphological Sciences, Kagoshima University Graduate School of Medical and Dental Sciences, 8-35-1, Sakuragaoka, Kagoshima 890-8544, Japan
| | - Hirokazu Yagi
- Graduate School of Pharmaceutical Sciences, Nagoya City University, Tanabe-dori 3-1, Mizuho-ku, Nagoya 467-8603, Japan
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji-cho, Okazaki 444-8787, Japan
| | - Koichi Kato
- Graduate School of Pharmaceutical Sciences, Nagoya City University, Tanabe-dori 3-1, Mizuho-ku, Nagoya 467-8603, Japan
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji-cho, Okazaki 444-8787, Japan
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2
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Silva-Palacios A, Zazueta C, Pedraza-Chaverri J. ER membranes associated with mitochondria: Possible therapeutic targets in heart-associated diseases. Pharmacol Res 2020; 156:104758. [PMID: 32200027 DOI: 10.1016/j.phrs.2020.104758] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 02/06/2020] [Accepted: 03/16/2020] [Indexed: 12/14/2022]
Abstract
Cardiovascular system cell biology is tightly regulated and mitochondria play a relevant role in maintaining heart function. In recent decades, associations between such organelles and the sarco/endoplasmic reticulum (SR) have been raised great interest. Formally identified as mitochondria-associated SR membranes (MAMs), these structures regulate different cellular functions, including calcium management, lipid metabolism, autophagy, oxidative stress, and management of unfolded proteins. In this review, we highlight MAMs' alterations mainly in cardiomyocytes, linked with cardiovascular diseases, such as cardiac ischemia-reperfusion, heart failure, and dilated cardiomyopathy. We also describe proteins that are part of the MAMs' machinery, as the FUN14 domain containing 1 (FUNDC1), the sigma 1 receptor (Sig-1R) and others, which might be new molecular targets to preserve the function and structure of the heart in such diseases. Understanding the machinery of MAMs and its function demands our attention, as such knowledge might contribute to strengthen the role of these relative novel structures in heart diseases.
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Affiliation(s)
- Alejandro Silva-Palacios
- Department of Cardiovascular Biomedicine, National Institute of Cardiology-Ignacio Chávez, Mexico City, Mexico.
| | - Cecilia Zazueta
- Department of Cardiovascular Biomedicine, National Institute of Cardiology-Ignacio Chávez, Mexico City, Mexico
| | - José Pedraza-Chaverri
- Department of Biology, Faculty of Chemistry, National Autonomous University of Mexico, Circuito Exterior S/N, C. U., 04510, Mexico City, Mexico.
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3
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Ju L, Tong W, Qiu M, Shen W, Sun J, Zheng S, Chen Y, Liu W, Tian J. Antioxidant MMCC ameliorates catch-up growth related metabolic dysfunction. Oncotarget 2017; 8:99931-99939. [PMID: 29245950 PMCID: PMC5725141 DOI: 10.18632/oncotarget.21965] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Accepted: 09/29/2017] [Indexed: 11/25/2022] Open
Abstract
Postnatal catch-up growth may be related to reduce mitochondrial content and oxidation capacity in skeletal muscle. The aim of this study is to explore the effect and mechanism of antioxidant MitoQuinone mesylate beta cyclodextrin complex (MMCC) ameliorates catch-up growth related metabolic disorders. Catch-up growth mice were created by restricting maternal food intake during the last week of gestation and providing high fat diet after weaning. Low birthweight mice and normal birthweight controls were randomly subjected to normal fat diet, high fat diet and high fat diet with MMCC drinking from the 4th week. MMCC treatment for 21 weeks slowed down the catch up growth and ameliorated catch-up growth related obesity, glucose intolerance and insulin resistance. MMCC administration significantly inhibited the peroxidation of the membrane lipid and up-regulated the antioxidant enzymes Catalase and MnSOD. In addition, MMCC treatment effectively enhanced mitochondrial functions in skeletal muscle through the up-regulation of the ATP generation, and the promotion of mitochondrial replication and remodeling. To conclude, this study demonstrates that antioxidant MMCC effectively ameliorates catch-up growth related metabolic dysfunctions by increasing mitochondrial functions in skeletal muscle.
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Affiliation(s)
- Liping Ju
- Shanghai Clinical Center for Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Department of Endocrinology and Metabolism, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Wenxin Tong
- Shanghai Clinical Center for Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Department of Endocrinology and Metabolism, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Department of Diabetes Complications and Metabolism, Beckman Research Institute of City of Hope, Duarte, CA, USA
| | - Miaoyan Qiu
- Shanghai Clinical Center for Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Department of Endocrinology and Metabolism, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Weili Shen
- Shanghai Institute of Hypertension, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Jichao Sun
- Laboratory of Endocrine and Metabolic Diseases, Institute of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, and Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Sheng Zheng
- Shanghai Clinical Center for Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Department of Endocrinology and Metabolism, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Ying Chen
- Shanghai Clinical Center for Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Department of Endocrinology and Metabolism, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Wentao Liu
- Key Laboratory of Shanghai Gastric Neoplasms, Department of Surgery, Ruijin Hospital, Shanghai Jiao Tong University, Shanghai Institute of Digestive Surgery, Shanghai, China
| | - Jingyan Tian
- Shanghai Clinical Center for Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Department of Endocrinology and Metabolism, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Department of Diabetes Complications and Metabolism, Beckman Research Institute of City of Hope, Duarte, CA, USA
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4
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Wang Y, Wilson C, Cartwright EJ, Lei M. Plasma membrane Ca 2+ -ATPase 1 is required for maintaining atrial Ca 2+ homeostasis and electrophysiological stability in the mouse. J Physiol 2017; 595:7383-7398. [PMID: 29023784 PMCID: PMC5730856 DOI: 10.1113/jp274110] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 10/06/2017] [Indexed: 11/22/2022] Open
Abstract
Key points The role of plasma membrane Ca2+‐ATPase 1 (PMCA1) in Ca2+ homeostasis and electrical stability in atrial tissue has been investigated at both organ and cellular levels in mice with cardiomyocyte‐specific deletion of PMCA1 (PMCA1cko) The PMCA1cko hearts became more susceptible to atrial arrhythmic stress conditions than PMCA1loxP/loxP hearts. PMCA1 deficiency alters cellular Ca2+ homeostasis under both baseline and stress conditions. PMCA1 is required for maintaining cellular Ca2+ homeostasis and electrical stability in murine atria under stress conditions.
Abstract To determine the role of plasma membrane Ca2+‐ATPase 1 (PMCA1) in maintaining Ca2+ homeostasis and electrical stability in the atrium under physiological and stress conditions, mice with a cardiomyocyte‐specific deletion of PMCA1 (PMCA1cko) and their control littermates (PMCA1loxP/loxP) were studied at the organ and cellular levels. At the organ level, the PMCA1cko hearts became more susceptible to atrial arrhythmias under rapid programmed electrical stimulation compared with the PMCA1loxP/loxP hearts, and such arrhythmic events became more severe under Ca2+ overload conditions. At the cellular level, the occurrence of irregular‐type action potentials of PMCA1cko atrial myocytes increased significantly under Ca2+ overload conditions and/or at higher frequency of stimulation. The decay of Na+/Ca2+ exchanger current that followed a stimulation protocol was significantly prolonged in PMCA1cko atrial myocytes under basal conditions, with Ca2+ overload leading to even greater prolongation. In conclusion, PMCA1 is required for maintaining Ca2+ homeostasis and electrical stability in the atrium. This is particularly critical during fast removal of Ca2+ from the cytosol, which is required under stress conditions. The role of plasma membrane Ca2+‐ATPase 1 (PMCA1) in Ca2+ homeostasis and electrical stability in atrial tissue has been investigated at both organ and cellular levels in mice with cardiomyocyte‐specific deletion of PMCA1 (PMCA1cko) The PMCA1cko hearts became more susceptible to atrial arrhythmic stress conditions than PMCA1loxP/loxP hearts. PMCA1 deficiency alters cellular Ca2+ homeostasis under both baseline and stress conditions. PMCA1 is required for maintaining cellular Ca2+ homeostasis and electrical stability in murine atria under stress conditions.
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Affiliation(s)
- Yanwen Wang
- Department of Pharmacology, University of Oxford, Oxford, UK.,Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK
| | - Claire Wilson
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK
| | - Elizabeth J Cartwright
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK
| | - Ming Lei
- Department of Pharmacology, University of Oxford, Oxford, UK
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5
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Kallepitis C, Bergholt MS, Mazo MM, Leonardo V, Skaalure SC, Maynard SA, Stevens MM. Quantitative volumetric Raman imaging of three dimensional cell cultures. Nat Commun 2017; 8:14843. [PMID: 28327660 PMCID: PMC5364421 DOI: 10.1038/ncomms14843] [Citation(s) in RCA: 85] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Accepted: 02/03/2017] [Indexed: 02/07/2023] Open
Abstract
The ability to simultaneously image multiple biomolecules in biologically relevant three-dimensional (3D) cell culture environments would contribute greatly to the understanding of complex cellular mechanisms and cell-material interactions. Here, we present a computational framework for label-free quantitative volumetric Raman imaging (qVRI). We apply qVRI to a selection of biological systems: human pluripotent stem cells with their cardiac derivatives, monocytes and monocyte-derived macrophages in conventional cell culture systems and mesenchymal stem cells inside biomimetic hydrogels that supplied a 3D cell culture environment. We demonstrate visualization and quantification of fine details in cell shape, cytoplasm, nucleus, lipid bodies and cytoskeletal structures in 3D with unprecedented biomolecular specificity for vibrational microspectroscopy.
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Affiliation(s)
- Charalambos Kallepitis
- Department of Materials, Imperial College London, London SW7 2AZ, UK
- Department of Bioengineering, Imperial College London, London SW7 2AZ, UK
- Institute of Biomedical Engineering, Imperial College London, London SW7 2AZ, UK
| | - Mads S. Bergholt
- Department of Materials, Imperial College London, London SW7 2AZ, UK
- Department of Bioengineering, Imperial College London, London SW7 2AZ, UK
- Institute of Biomedical Engineering, Imperial College London, London SW7 2AZ, UK
| | - Manuel M. Mazo
- Department of Materials, Imperial College London, London SW7 2AZ, UK
- Department of Bioengineering, Imperial College London, London SW7 2AZ, UK
- Institute of Biomedical Engineering, Imperial College London, London SW7 2AZ, UK
| | - Vincent Leonardo
- Department of Materials, Imperial College London, London SW7 2AZ, UK
- Department of Bioengineering, Imperial College London, London SW7 2AZ, UK
- Institute of Biomedical Engineering, Imperial College London, London SW7 2AZ, UK
| | - Stacey C. Skaalure
- Department of Materials, Imperial College London, London SW7 2AZ, UK
- Department of Bioengineering, Imperial College London, London SW7 2AZ, UK
- Institute of Biomedical Engineering, Imperial College London, London SW7 2AZ, UK
| | - Stephanie A. Maynard
- Department of Materials, Imperial College London, London SW7 2AZ, UK
- Department of Bioengineering, Imperial College London, London SW7 2AZ, UK
- Institute of Biomedical Engineering, Imperial College London, London SW7 2AZ, UK
| | - Molly M. Stevens
- Department of Materials, Imperial College London, London SW7 2AZ, UK
- Department of Bioengineering, Imperial College London, London SW7 2AZ, UK
- Institute of Biomedical Engineering, Imperial College London, London SW7 2AZ, UK
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6
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Goette A, Kalman JM, Aguinaga L, Akar J, Cabrera JA, Chen SA, Chugh SS, Corradi D, D'Avila A, Dobrev D, Fenelon G, Gonzalez M, Hatem SN, Helm R, Hindricks G, Ho SY, Hoit B, Jalife J, Kim YH, Lip GYH, Ma CS, Marcus GM, Murray K, Nogami A, Sanders P, Uribe W, Van Wagoner DR, Nattel S. EHRA/HRS/APHRS/SOLAECE expert consensus on Atrial cardiomyopathies: Definition, characterisation, and clinical implication. J Arrhythm 2016; 32:247-78. [PMID: 27588148 PMCID: PMC4996910 DOI: 10.1016/j.joa.2016.05.002] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Affiliation(s)
- Andreas Goette
- Departement of Cardiology and Intensive Care Medicine, St. Vincenz-Hospital Paderborn, Working Group: Molecular Electrophysiology, University Hospital Magdeburg, Germany
| | - Jonathan M Kalman
- University of Melbourne, Royal Melbourne Hospital, Melbourne, VIC, Australia
| | | | | | | | | | - Sumeet S Chugh
- The Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | | | | | - Dobromir Dobrev
- Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Essen, Germany
| | | | - Mario Gonzalez
- Penn State Heart and Vascular Institute, Penn State University, Hershey, PA, USA
| | - Stephane N Hatem
- Department of Cardiology, Assistance Publique - Hô pitaux de Paris, Pitié-Salpêtrière Hospital, Sorbonne University, INSERM UMR_S1166, Institute of Cardiometabolism and Nutrition-ICAN, Paris, France
| | - Robert Helm
- Boston University School of Medicine, Boston Medical Center, Boston, MA, USA
| | | | - Siew Yen Ho
- Royal Brompton Hospital and Imperial College London, London, UK
| | - Brian Hoit
- UH Case Medical Center, Cleveland, OH, USA
| | | | | | | | | | | | | | | | - Prashanthan Sanders
- Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - William Uribe
- Electrophysiology Deparment at Centros Especializados de San Vicente Fundació n and Clínica CES. Universidad CES, Universidad Pontificia Bolivariana (UPB), Medellin, Colombia
| | | | - Stanley Nattel
- Université de Montréal, Montreal Heart Institute Research Center and McGill University, Montreal, Quebec, Canada; Institute of Pharmacology, West German Heart and Vascular Center, Faculty of Medicine, University Duisburg-Essen, Essen, Germany
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7
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Goette A, Kalman JM, Aguinaga L, Akar J, Cabrera JA, Chen SA, Chugh SS, Corradi D, D'Avila A, Dobrev D, Fenelon G, Gonzalez M, Hatem SN, Helm R, Hindricks G, Ho SY, Hoit B, Jalife J, Kim YH, Lip GYH, Ma CS, Marcus GM, Murray K, Nogami A, Sanders P, Uribe W, Van Wagoner DR, Nattel S. EHRA/HRS/APHRS/SOLAECE expert consensus on atrial cardiomyopathies: definition, characterization, and clinical implication. Europace 2016; 18:1455-1490. [PMID: 27402624 DOI: 10.1093/europace/euw161] [Citation(s) in RCA: 426] [Impact Index Per Article: 53.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Affiliation(s)
- Andreas Goette
- Departement of Cardiology and Intensive Care Medicine, St. Vincenz-Hospital Paderborn, Working Group: Molecular Electrophysiology, University Hospital Magdeburg, Germany
| | - Jonathan M Kalman
- University of Melbourne, Royal Melbourne Hospital, Melbourne, VIC, Australia
| | | | | | | | | | - Sumeet S Chugh
- The Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | | | | | - Dobromir Dobrev
- Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Essen, Germany
| | | | - Mario Gonzalez
- Penn State Heart and Vascular Institute, Penn State University, Hershey, PA, USA
| | - Stephane N Hatem
- Department of Cardiology, Assistance Publique - Hôpitaux de Paris, Pitié-Salpêtrière Hospital; Sorbonne University; INSERM UMR_S1166; Institute of Cardiometabolism and Nutrition-ICAN, Paris, France
| | - Robert Helm
- Boston University School of Medicine, Boston Medical Center, Boston, MA, USA
| | | | - Siew Yen Ho
- Royal Brompton Hospital and Imperial College London, London, UK
| | - Brian Hoit
- UH Case Medical Center, Cleveland, OH, USA
| | | | | | | | | | | | | | | | - Prashanthan Sanders
- Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - William Uribe
- Electrophysiology Deparment at Centros Especializados de San Vicente Fundación and Clínica CES. Universidad CES, Universidad Pontificia Bolivariana (UPB), Medellin, Colombia
| | | | - Stanley Nattel
- Université de Montréal, Montreal Heart Institute Research Center and McGill University, Montreal, Quebec, Canada .,Institute of Pharmacology, West German Heart and Vascular Center, Faculty of Medicine, University Duisburg-Essen, Essen, Germany
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8
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EHRA/HRS/APHRS/SOLAECE expert consensus on atrial cardiomyopathies: Definition, characterization, and clinical implication. Heart Rhythm 2016; 14:e3-e40. [PMID: 27320515 DOI: 10.1016/j.hrthm.2016.05.028] [Citation(s) in RCA: 213] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Indexed: 12/21/2022]
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9
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Leduc-Gaudet JP, Picard M, St-Jean Pelletier F, Sgarioto N, Auger MJ, Vallée J, Robitaille R, St-Pierre DH, Gouspillou G. Mitochondrial morphology is altered in atrophied skeletal muscle of aged mice. Oncotarget 2016; 6:17923-37. [PMID: 26053100 PMCID: PMC4627226 DOI: 10.18632/oncotarget.4235] [Citation(s) in RCA: 181] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Accepted: 05/12/2015] [Indexed: 02/05/2023] Open
Abstract
Skeletal muscle aging is associated with a progressive decline in muscle mass and strength, a process termed sarcopenia. Evidence suggests that accumulation of mitochondrial dysfunction plays a causal role in sarcopenia, which could be triggered by impaired mitophagy. Mitochondrial function, mitophagy and mitochondrial morphology are interconnected aspects of mitochondrial biology, and may coordinately be altered with aging. However, mitochondrial morphology has remained challenging to characterize in muscle, and whether sarcopenia is associated with abnormal mitochondrial morphology remains unknown. Therefore, we assessed the morphology of SubSarcolemmal (SS) and InterMyoFibrillar (IMF) mitochondria in skeletal muscle of young (8-12wk-old) and old (88-96wk-old) mice using a quantitative 2-dimensional transmission electron microscopy approach. We show that sarcopenia is associated with larger and less circular SS mitochondria. Likewise, aged IMF mitochondria were longer and more branched, suggesting increased fusion and/or decreased fission. Accordingly, although no difference in the content of proteins regulating mitochondrial dynamics (Mfn1, Mfn2, Opa1 and Drp1) was observed, a mitochondrial fusion index (Mfn2-to-Drp1 ratio) was significantly increased in aged muscles. Our results reveal that sarcopenia is associated with complex changes in mitochondrial morphology that could interfere with mitochondrial function and mitophagy, and thus contribute to aging-related accumulation of mitochondrial dysfunction and sarcopenia.
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Affiliation(s)
- Jean-Philippe Leduc-Gaudet
- Département des Sciences de l'Activité Physique, Faculté des Sciences, UQAM, Montréal, Canada.,Groupe de Recherche en Activité Physique Adaptée, Montréal, Canada.,Centre de Recherche du CHU Sainte-Justine, Montréal, Canada
| | - Martin Picard
- The Center for Mitochondrial and Epigenomic Medicine, Children's Hospital of Philadelphia and University of Pennsylvania, Philadelphia, PA, USA
| | - Félix St-Jean Pelletier
- Département des Sciences de l'Activité Physique, Faculté des Sciences, UQAM, Montréal, Canada
| | - Nicolas Sgarioto
- Département des Sciences de l'Activité Physique, Faculté des Sciences, UQAM, Montréal, Canada
| | - Marie-Joëlle Auger
- Département des Sciences de l'Activité Physique, Faculté des Sciences, UQAM, Montréal, Canada
| | - Joanne Vallée
- Département de Neurosciences, Université de Montréal, Montréal, Canada
| | - Richard Robitaille
- Département de Neurosciences, Université de Montréal, Montréal, Canada.,Groupe de Recherche sur le Système Nerveux Central, Montréal, Canada
| | - David H St-Pierre
- Département des Sciences de l'Activité Physique, Faculté des Sciences, UQAM, Montréal, Canada.,Groupe de Recherche en Activité Physique Adaptée, Montréal, Canada.,Centre de Recherche du CHU Sainte-Justine, Montréal, Canada
| | - Gilles Gouspillou
- Département des Sciences de l'Activité Physique, Faculté des Sciences, UQAM, Montréal, Canada.,Groupe de Recherche en Activité Physique Adaptée, Montréal, Canada.,Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, Montréal, Canada
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10
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Zhang H, Cannell MB, Kim SJ, Watson JJ, Norman R, Calaghan SC, Orchard CH, James AF. Cellular Hypertrophy and Increased Susceptibility to Spontaneous Calcium-Release of Rat Left Atrial Myocytes Due to Elevated Afterload. PLoS One 2015; 10:e0144309. [PMID: 26713852 PMCID: PMC4694654 DOI: 10.1371/journal.pone.0144309] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 11/16/2015] [Indexed: 11/19/2022] Open
Abstract
Atrial remodeling due to elevated arterial pressure predisposes the heart to atrial fibrillation (AF). Although abnormal sarcoplasmic reticulum (SR) function has been associated with AF, there is little information on the effects of elevated afterload on atrial Ca2+-handling. We investigated the effects of ascending aortic banding (AoB) on Ca2+-handling in rat isolated atrial myocytes in comparison to age-matched sham-operated animals (Sham). Myocytes were either labelled for ryanodine receptor (RyR) or loaded with fluo-3-AM and imaged by confocal microscopy. AoB myocytes were hypertrophied in comparison to Sham controls (P<0.0001). RyR labeling was localized to the z-lines and to the cell edge. There were no differences between AoB and Sham in the intensity or pattern of RyR-staining. In both AoB and Sham, electrical stimulation evoked robust SR Ca2+-release at the cell edge whereas Ca2+ transients at the cell center were much smaller. Western blotting showed a decreased L-type Ca channel expression but no significant changes in RyR or RyR phosphorylation or in expression of Na+/Ca2+ exchanger, SR Ca2+ ATPase or phospholamban. Mathematical modeling indicated that [Ca2+]i transients at the cell center were accounted for by simple centripetal diffusion of Ca2+ released at the cell edge. In contrast, caffeine (10 mM) induced Ca2+ release was uniform across the cell. The caffeine-induced transient was smaller in AoB than in Sham, suggesting a reduced SR Ca2+-load in hypertrophied cells. There were no significant differences between AoB and Sham cells in the rate of Ca2+ extrusion during recovery of electrically-stimulated or caffeine-induced transients. The incidence and frequency of spontaneous Ca2+-transients following rapid-pacing (4 Hz) was greater in AoB than in Sham myocytes. In conclusion, elevated afterload causes cellular hypertrophy and remodeling of atrial SR Ca2+-release.
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Affiliation(s)
- Haifei Zhang
- Cardiovascular Research Laboratories, School of Physiology, Pharmacology & Neuroscience, University of Bristol, Bristol, BS8 1TD, United Kingdom
| | - Mark B. Cannell
- Cardiovascular Research Laboratories, School of Physiology, Pharmacology & Neuroscience, University of Bristol, Bristol, BS8 1TD, United Kingdom
| | - Shang Jin Kim
- Cardiovascular Research Laboratories, School of Physiology, Pharmacology & Neuroscience, University of Bristol, Bristol, BS8 1TD, United Kingdom
| | - Judy J. Watson
- Cardiovascular Research Laboratories, School of Physiology, Pharmacology & Neuroscience, University of Bristol, Bristol, BS8 1TD, United Kingdom
| | - Ruth Norman
- School of Biomedical Sciences, Garstang, University of Leeds, Leeds, LS2 9JT, United Kingdom
| | - Sarah C. Calaghan
- School of Biomedical Sciences, Garstang, University of Leeds, Leeds, LS2 9JT, United Kingdom
| | - Clive H. Orchard
- Cardiovascular Research Laboratories, School of Physiology, Pharmacology & Neuroscience, University of Bristol, Bristol, BS8 1TD, United Kingdom
| | - Andrew F. James
- Cardiovascular Research Laboratories, School of Physiology, Pharmacology & Neuroscience, University of Bristol, Bristol, BS8 1TD, United Kingdom
- * E-mail:
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11
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Glukhov AV, Balycheva M, Sanchez-Alonso JL, Ilkan Z, Alvarez-Laviada A, Bhogal N, Diakonov I, Schobesberger S, Sikkel MB, Bhargava A, Faggian G, Punjabi PP, Houser SR, Gorelik J. Direct Evidence for Microdomain-Specific Localization and Remodeling of Functional L-Type Calcium Channels in Rat and Human Atrial Myocytes. Circulation 2015; 132:2372-84. [PMID: 26450916 PMCID: PMC4689179 DOI: 10.1161/circulationaha.115.018131] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Accepted: 10/02/2015] [Indexed: 12/27/2022]
Abstract
Supplemental Digital Content is available in the text. Distinct subpopulations of L-type calcium channels (LTCCs) with different functional properties exist in cardiomyocytes. Disruption of cellular structure may affect LTCC in a microdomain-specific manner and contribute to the pathophysiology of cardiac diseases, especially in cells lacking organized transverse tubules (T-tubules) such as atrial myocytes (AMs).
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Affiliation(s)
- Alexey V Glukhov
- From Department of Cardiovascular Sciences, National Heart and Lung Institute, Imperial College London, United Kingdom (A.V.G., M.B., J.L.S.-A., Z.I., A.A.-L., N.B., I.D., S.S., M.B.S., A.B., P.P.P., J.G.); University of Verona, School of Medicine, Verona, Italy (M.B., G.F.); Department of Cardiothoracic Surgery, Hammersmith Hospital, National Heart and Lung Institute, Imperial College London, United Kingdom (P.P.P.); and Cardiovascular Research Center and Department of Physiology, Temple University School of Medicine, Philadelphia, PA (S.R.H.)
| | - Marina Balycheva
- From Department of Cardiovascular Sciences, National Heart and Lung Institute, Imperial College London, United Kingdom (A.V.G., M.B., J.L.S.-A., Z.I., A.A.-L., N.B., I.D., S.S., M.B.S., A.B., P.P.P., J.G.); University of Verona, School of Medicine, Verona, Italy (M.B., G.F.); Department of Cardiothoracic Surgery, Hammersmith Hospital, National Heart and Lung Institute, Imperial College London, United Kingdom (P.P.P.); and Cardiovascular Research Center and Department of Physiology, Temple University School of Medicine, Philadelphia, PA (S.R.H.)
| | - Jose L Sanchez-Alonso
- From Department of Cardiovascular Sciences, National Heart and Lung Institute, Imperial College London, United Kingdom (A.V.G., M.B., J.L.S.-A., Z.I., A.A.-L., N.B., I.D., S.S., M.B.S., A.B., P.P.P., J.G.); University of Verona, School of Medicine, Verona, Italy (M.B., G.F.); Department of Cardiothoracic Surgery, Hammersmith Hospital, National Heart and Lung Institute, Imperial College London, United Kingdom (P.P.P.); and Cardiovascular Research Center and Department of Physiology, Temple University School of Medicine, Philadelphia, PA (S.R.H.)
| | - Zeki Ilkan
- From Department of Cardiovascular Sciences, National Heart and Lung Institute, Imperial College London, United Kingdom (A.V.G., M.B., J.L.S.-A., Z.I., A.A.-L., N.B., I.D., S.S., M.B.S., A.B., P.P.P., J.G.); University of Verona, School of Medicine, Verona, Italy (M.B., G.F.); Department of Cardiothoracic Surgery, Hammersmith Hospital, National Heart and Lung Institute, Imperial College London, United Kingdom (P.P.P.); and Cardiovascular Research Center and Department of Physiology, Temple University School of Medicine, Philadelphia, PA (S.R.H.)
| | - Anita Alvarez-Laviada
- From Department of Cardiovascular Sciences, National Heart and Lung Institute, Imperial College London, United Kingdom (A.V.G., M.B., J.L.S.-A., Z.I., A.A.-L., N.B., I.D., S.S., M.B.S., A.B., P.P.P., J.G.); University of Verona, School of Medicine, Verona, Italy (M.B., G.F.); Department of Cardiothoracic Surgery, Hammersmith Hospital, National Heart and Lung Institute, Imperial College London, United Kingdom (P.P.P.); and Cardiovascular Research Center and Department of Physiology, Temple University School of Medicine, Philadelphia, PA (S.R.H.)
| | - Navneet Bhogal
- From Department of Cardiovascular Sciences, National Heart and Lung Institute, Imperial College London, United Kingdom (A.V.G., M.B., J.L.S.-A., Z.I., A.A.-L., N.B., I.D., S.S., M.B.S., A.B., P.P.P., J.G.); University of Verona, School of Medicine, Verona, Italy (M.B., G.F.); Department of Cardiothoracic Surgery, Hammersmith Hospital, National Heart and Lung Institute, Imperial College London, United Kingdom (P.P.P.); and Cardiovascular Research Center and Department of Physiology, Temple University School of Medicine, Philadelphia, PA (S.R.H.)
| | - Ivan Diakonov
- From Department of Cardiovascular Sciences, National Heart and Lung Institute, Imperial College London, United Kingdom (A.V.G., M.B., J.L.S.-A., Z.I., A.A.-L., N.B., I.D., S.S., M.B.S., A.B., P.P.P., J.G.); University of Verona, School of Medicine, Verona, Italy (M.B., G.F.); Department of Cardiothoracic Surgery, Hammersmith Hospital, National Heart and Lung Institute, Imperial College London, United Kingdom (P.P.P.); and Cardiovascular Research Center and Department of Physiology, Temple University School of Medicine, Philadelphia, PA (S.R.H.)
| | - Sophie Schobesberger
- From Department of Cardiovascular Sciences, National Heart and Lung Institute, Imperial College London, United Kingdom (A.V.G., M.B., J.L.S.-A., Z.I., A.A.-L., N.B., I.D., S.S., M.B.S., A.B., P.P.P., J.G.); University of Verona, School of Medicine, Verona, Italy (M.B., G.F.); Department of Cardiothoracic Surgery, Hammersmith Hospital, National Heart and Lung Institute, Imperial College London, United Kingdom (P.P.P.); and Cardiovascular Research Center and Department of Physiology, Temple University School of Medicine, Philadelphia, PA (S.R.H.)
| | - Markus B Sikkel
- From Department of Cardiovascular Sciences, National Heart and Lung Institute, Imperial College London, United Kingdom (A.V.G., M.B., J.L.S.-A., Z.I., A.A.-L., N.B., I.D., S.S., M.B.S., A.B., P.P.P., J.G.); University of Verona, School of Medicine, Verona, Italy (M.B., G.F.); Department of Cardiothoracic Surgery, Hammersmith Hospital, National Heart and Lung Institute, Imperial College London, United Kingdom (P.P.P.); and Cardiovascular Research Center and Department of Physiology, Temple University School of Medicine, Philadelphia, PA (S.R.H.)
| | - Anamika Bhargava
- From Department of Cardiovascular Sciences, National Heart and Lung Institute, Imperial College London, United Kingdom (A.V.G., M.B., J.L.S.-A., Z.I., A.A.-L., N.B., I.D., S.S., M.B.S., A.B., P.P.P., J.G.); University of Verona, School of Medicine, Verona, Italy (M.B., G.F.); Department of Cardiothoracic Surgery, Hammersmith Hospital, National Heart and Lung Institute, Imperial College London, United Kingdom (P.P.P.); and Cardiovascular Research Center and Department of Physiology, Temple University School of Medicine, Philadelphia, PA (S.R.H.)
| | - Giuseppe Faggian
- From Department of Cardiovascular Sciences, National Heart and Lung Institute, Imperial College London, United Kingdom (A.V.G., M.B., J.L.S.-A., Z.I., A.A.-L., N.B., I.D., S.S., M.B.S., A.B., P.P.P., J.G.); University of Verona, School of Medicine, Verona, Italy (M.B., G.F.); Department of Cardiothoracic Surgery, Hammersmith Hospital, National Heart and Lung Institute, Imperial College London, United Kingdom (P.P.P.); and Cardiovascular Research Center and Department of Physiology, Temple University School of Medicine, Philadelphia, PA (S.R.H.)
| | - Prakash P Punjabi
- From Department of Cardiovascular Sciences, National Heart and Lung Institute, Imperial College London, United Kingdom (A.V.G., M.B., J.L.S.-A., Z.I., A.A.-L., N.B., I.D., S.S., M.B.S., A.B., P.P.P., J.G.); University of Verona, School of Medicine, Verona, Italy (M.B., G.F.); Department of Cardiothoracic Surgery, Hammersmith Hospital, National Heart and Lung Institute, Imperial College London, United Kingdom (P.P.P.); and Cardiovascular Research Center and Department of Physiology, Temple University School of Medicine, Philadelphia, PA (S.R.H.)
| | - Steven R Houser
- From Department of Cardiovascular Sciences, National Heart and Lung Institute, Imperial College London, United Kingdom (A.V.G., M.B., J.L.S.-A., Z.I., A.A.-L., N.B., I.D., S.S., M.B.S., A.B., P.P.P., J.G.); University of Verona, School of Medicine, Verona, Italy (M.B., G.F.); Department of Cardiothoracic Surgery, Hammersmith Hospital, National Heart and Lung Institute, Imperial College London, United Kingdom (P.P.P.); and Cardiovascular Research Center and Department of Physiology, Temple University School of Medicine, Philadelphia, PA (S.R.H.)
| | - Julia Gorelik
- From Department of Cardiovascular Sciences, National Heart and Lung Institute, Imperial College London, United Kingdom (A.V.G., M.B., J.L.S.-A., Z.I., A.A.-L., N.B., I.D., S.S., M.B.S., A.B., P.P.P., J.G.); University of Verona, School of Medicine, Verona, Italy (M.B., G.F.); Department of Cardiothoracic Surgery, Hammersmith Hospital, National Heart and Lung Institute, Imperial College London, United Kingdom (P.P.P.); and Cardiovascular Research Center and Department of Physiology, Temple University School of Medicine, Philadelphia, PA (S.R.H.).
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12
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Bers DM, Shannon TR. Calcium movements inside the sarcoplasmic reticulum of cardiac myocytes. J Mol Cell Cardiol 2013; 58:59-66. [PMID: 23321551 PMCID: PMC3628081 DOI: 10.1016/j.yjmcc.2013.01.002] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Revised: 12/17/2012] [Accepted: 01/04/2013] [Indexed: 02/03/2023]
Abstract
Sarcoplasmic reticulum (SR) Ca content ([Ca]SRT) is critical to both normal cardiac function and electrophysiology, and changes associated with pathology contribute to systolic and diastolic dysfunction and arrhythmias. The intra-SR free [Ca] ([Ca]SR) dictates the [Ca]SRT, the driving force for Ca release and regulates release channel gating. We discuss measurement of [Ca]SR and [Ca]SRT, how [Ca]SR regulates activation and termination of release, and how Ca diffuses within the SR and influences SR Ca release during excitation-contraction coupling, Ca sparks and Cac waves. The entire SR network is connected and its lumen is also continuous with the nuclear envelope. Rapid Ca diffusion within the SR could stabilize and balance local [Ca]SR within the myocyte, but restrictions to diffusion can create spatial inhomogeneities. Experimental measurements and mathematical models of [Ca]SR to date have greatly enriched our understanding of these [Ca]SR dynamics, but controversies exist and may stimulate new measurements and analysis.
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Affiliation(s)
- Donald M Bers
- Department of Pharmacology, University of California, Davis, Davis, CA, USA.
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13
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Horn T, Ullrich ND, Egger M. 'Eventless' InsP3-dependent SR-Ca2+ release affecting atrial Ca2+ sparks. J Physiol 2013; 591:2103-11. [PMID: 23381902 DOI: 10.1113/jphysiol.2012.247288] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Augmented inositol 1,4,5-trisphosphate receptor (InsP3R) function has been linked to a variety of cardiac pathologies, including cardiac arrhythmia. The contribution of inositol 1,4,5-trisphosphate-induced Ca(2+) release (IP3ICR) in excitation-contraction coupling (ECC) under physiological conditions, as well as under cellular remodelling, remains controversial. Here we test the hypothesis that local IP3ICR directly affects ryanodine receptor (RyR) function and subsequent Ca(2+)-induced Ca(2+) release in atrial myocytes. IP3ICR was evoked by UV-flash photolysis of caged InsP3 under whole-cell configuration of the voltage-clamp technique in atrial myocytes isolated from C57/BL6 mice. Photolytic release of InsP3 was accompanied by a significant increase in the Ca(2+) release event frequency (4.14 ± 0.72 vs. 6.20 ± 0.76 events (100 μm)(-1) s(-1)). These individual photolytically triggered Ca(2+) release events were identified as Ca(2+) sparks, which originated from RyR openings. This was verified by Ca(2+) spark analysis and pharmacological separation between RyR and InsP3R-dependent sarcoplasmic reticulum (SR)-Ca(2+) release (2-aminoethoxydiphenyl borate, xestospongin C, tetracaine). Significant SR-Ca(2+) flux but eventless SR-Ca(2+) release through InsP3R were characterized using SR-Ca(2+) leak/SR-Ca(2+) load measurements. These results strongly support the idea that IP3ICR can effectively modulate RyR openings and Ca(2+) spark probability. We conclude that eventless and highly efficient InsP3-dependent SR-Ca(2+) flux is the main mechanism of functional cross-talk between InsP3Rs and RyRs, which may be an important factor in the modulation of ECC sensitivity.
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Affiliation(s)
- Tamara Horn
- Department of Physiology, University of Bern, Bühlplatz 5, CH-3012 Bern, Switzerland
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14
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Collins TP, Bayliss R, Churchill GC, Galione A, Terrar DA. NAADP influences excitation-contraction coupling by releasing calcium from lysosomes in atrial myocytes. Cell Calcium 2011; 50:449-58. [PMID: 21906808 DOI: 10.1016/j.ceca.2011.07.007] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2011] [Revised: 07/18/2011] [Accepted: 07/26/2011] [Indexed: 10/17/2022]
Abstract
In atrial myocytes, the sarcoplasmic reticulum (SR) has an essential role in regulating the force of contraction as a consequence of its involvement in excitation-contraction coupling (ECC). Nicotinic acid adenine dinucleotide phosphate (NAADP) is a Ca(2+) mobilizing messenger that acts to release Ca(2+) from an acidic store in mammalian cells. The photorelease of NAADP in atrial myocytes increased Ca(2+) transient amplitude with no effect on accompanying action potentials or the L-type Ca(2+) current. NAADP-AM, a cell permeant form of NAADP, increased Ca(2+) spark amplitude and frequency. The effect on Ca(2+) spark frequency could be prevented by bafilomycin A1, a vacuolar H(+)-ATPase inhibitor, or by disruption of lysosomes by GPN. Bafilomycin prevented staining of acidic stores with LysoTracker red by increasing lysosomal pH. NAADP-AM also produced an increase in the lysosomal pH, as detected by a reduction in LysoSensor green fluorescence. These effects of NAADP were associated with an increase in the amount of caffeine-releasable Ca(2+) in the SR and may be regulated by β-adrenoceptor stimulation with isoprenaline. These observations are consistent with a role for NAADP in regulating ECC in atrial myocytes by releasing Ca(2+) from an acidic store, which enhances SR Ca(2+) release by increasing SR load.
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Affiliation(s)
- Thomas P Collins
- Department of Pharmacology, University of Oxford, Mansfield Road, UK.
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15
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Bootman MD, Smyrnias I, Thul R, Coombes S, Roderick HL. Atrial cardiomyocyte calcium signalling. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2011; 1813:922-34. [DOI: 10.1016/j.bbamcr.2011.01.030] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2010] [Revised: 01/21/2011] [Accepted: 01/25/2011] [Indexed: 11/25/2022]
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16
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Schotten U, Verheule S, Kirchhof P, Goette A. Pathophysiological mechanisms of atrial fibrillation: a translational appraisal. Physiol Rev 2011; 91:265-325. [PMID: 21248168 DOI: 10.1152/physrev.00031.2009] [Citation(s) in RCA: 852] [Impact Index Per Article: 65.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Atrial fibrillation (AF) is an arrhythmia that can occur as the result of numerous different pathophysiological processes in the atria. Some aspects of the morphological and electrophysiological alterations promoting AF have been studied extensively in animal models. Atrial tachycardia or AF itself shortens atrial refractoriness and causes loss of atrial contractility. Aging, neurohumoral activation, and chronic atrial stretch due to structural heart disease activate a variety of signaling pathways leading to histological changes in the atria including myocyte hypertrophy, fibroblast proliferation, and complex alterations of the extracellular matrix including tissue fibrosis. These changes in electrical, contractile, and structural properties of the atria have been called "atrial remodeling." The resulting electrophysiological substrate is characterized by shortening of atrial refractoriness and reentrant wavelength or by local conduction heterogeneities caused by disruption of electrical interconnections between muscle bundles. Under these conditions, ectopic activity originating from the pulmonary veins or other sites is more likely to occur and to trigger longer episodes of AF. Many of these alterations also occur in patients with or at risk for AF, although the direct demonstration of these mechanisms is sometimes challenging. The diversity of etiological factors and electrophysiological mechanisms promoting AF in humans hampers the development of more effective therapy of AF. This review aims to give a translational overview on the biological basis of atrial remodeling and the proarrhythmic mechanisms involved in the fibrillation process. We pay attention to translation of pathophysiological insights gained from in vitro experiments and animal models to patients. Also, suggestions for future research objectives and therapeutical implications are discussed.
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Affiliation(s)
- Ulrich Schotten
- Department of Physiology, University Maastricht, Maastricht, The Netherlands.
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17
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Picht E, Zima AV, Shannon TR, Duncan AM, Blatter LA, Bers DM. Dynamic calcium movement inside cardiac sarcoplasmic reticulum during release. Circ Res 2011; 108:847-56. [PMID: 21311044 DOI: 10.1161/circresaha.111.240234] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
RATIONALE Intra-sarcoplasmic reticulum (SR) free [Ca] ([Ca](SR)) provides the driving force for SR Ca release and is a key regulator of SR Ca release channel gating during normal SR Ca release or arrhythmogenic spontaneous Ca release events. However, little is known about [Ca](SR) spatiotemporal dynamics. OBJECTIVE To directly measure local [Ca](SR) with subsarcomeric spatiotemporal resolution during both normal global SR Ca release and spontaneous Ca sparks and to evaluate the quantitative implications of spatial [Ca](SR) gradients. METHODS AND RESULTS Intact and permeabilized rabbit ventricular myocytes were subjected to direct simultaneous measurement of cytosolic [Ca] and [Ca](SR) and FRAP (fluorescence recovery after photobleach). We found no detectable [Ca](SR) gradients between SR release sites (junctional SR) and Ca uptake sites (free SR) during normal global Ca release, clear spatiotemporal [Ca](SR) gradients during isolated Ca blinks, faster intra-SR diffusion in the longitudinal versus transverse direction, 3- to 4-fold slower diffusion of fluorophores in the SR than in cytosol, and that intra-SR Ca diffusion varies locally, dependent on local SR connectivity. A computational model clarified why spatiotemporal gradients are more detectable in isolated local releases versus global releases and provides a quantitative framework for understanding intra-SR Ca diffusion. CONCLUSIONS Intra-SR Ca diffusion is rapid, limiting spatial [Ca](SR) gradients during excitation-contraction coupling. Spatiotemporal [Ca](SR) gradients are apparent during Ca sparks, and these observations constrain models of dynamic Ca movement inside the SR. This has important implications for myocyte SR Ca handling, synchrony, and potentially arrhythmogenic spontaneous contraction.
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Affiliation(s)
- Eckard Picht
- Department of Pharmacology, University of California-Davis, 451 Health Sciences Drive, Davis, CA 95616, USA
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18
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Ferlito M, Fulton WB, Zauher MA, Marbán E, Steenbergen C, Lowenstein CJ. VAMP-1, VAMP-2, and syntaxin-4 regulate ANP release from cardiac myocytes. J Mol Cell Cardiol 2010; 49:791-800. [PMID: 20801128 DOI: 10.1016/j.yjmcc.2010.08.020] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2010] [Revised: 08/19/2010] [Accepted: 08/20/2010] [Indexed: 01/24/2023]
Abstract
ANP is a peptide released by cardiac myocytes that regulates blood pressure and natriuresis. However, the molecular mechanisms controlling ANP release from cardiac myocytes are not defined. We now identify three components of the exocytic machinery that regulate ANP release from atrial myocytes. We found that cardiac myocytes express N-ethylmaleimide sensitive factor (NSF), soluble NSF attachment protein (α-SNAP), and SNAP receptors (SNAREs). Additionally we found that specific SNARE molecules, VAMP-1 and VAMP-2, both co-sediment and co-localize with ANP. Also, one SNARE molecule, syntaxin-4, partially co-sediments and partially co-localizes with ANP. Furthermore, these three SNAREs, syntaxin-4 and VAMP-1 and VAMP-2, form a SNARE complex inside cardiac myocytes. Finally, knockdown of VAMP-1, VAMP-2, or syntaxin-4 blocks regulated release of ANP. In contrast, silencing of VAMP-3 did not have an effect on ANP release. Our data suggest that three specific SNAREs regulate cardiac myocyte exocytosis of ANP. Pathways that modify the exocytic machinery may influence natriuresis and blood pressure.
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Affiliation(s)
- Marcella Ferlito
- Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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19
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Christ T, Galindo-Tovar A, Thoms M, Ravens U, Kaumann AJ. Inotropy and L-type Ca2+ current, activated by beta1- and beta2-adrenoceptors, are differently controlled by phosphodiesterases 3 and 4 in rat heart. Br J Pharmacol 2009; 156:62-83. [PMID: 19133992 DOI: 10.1111/j.1476-5381.2008.00015.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND AND PURPOSE beta(1)- and beta(2)-adrenoceptors coexist in rat heart but beta(2)-adrenoceptor-mediated inotropic effects are hardly detectable, possibly due to phosphodiesterase (PDE) activity. We investigated the influence of the PDE3 inhibitor cilostamide (300 nmol x L(-1)) and the PDE4 inhibitor rolipram (1 micromol x L(-1)) on the effects of (-)-catecholamines. EXPERIMENTAL APPROACH Cardiostimulation evoked by (-)-noradrenaline (ICI118551 present) and (-)-adrenaline (CGP20712A present) through beta(1)- and beta(2)-adrenoceptors, respectively, was compared on sinoatrial beating rate, left atrial and ventricular contractile force in isolated tissues from Wistar rats. L-type Ca(2+)-current (I(Ca-L)) was assessed with whole-cell patch clamp. KEY RESULTS Rolipram caused sinoatrial tachycardia. Cilostamide and rolipram did not enhance chronotropic potencies of (-)-noradrenaline and (-)-adrenaline. Rolipram but not cilostamide potentiated atrial and ventricular inotropic effects of (-)-noradrenaline. Cilostamide potentiated the ventricular effects of (-)-adrenaline but not of (-)-noradrenaline. Concurrent cilostamide + rolipram uncovered left atrial effects of (-)-adrenaline. Both rolipram and cilostamide augmented the (-)-noradrenaline (1 micromol x L(-1)) evoked increase in I(Ca-L). (-)-Adrenaline (10 micromol x L(-1)) increased I(Ca-L) only in the presence of cilostamide but not rolipram. CONCLUSIONS AND IMPLICATIONS PDE4 blunts the beta(1)-adrenoceptor-mediated inotropic effects. PDE4 reduces basal sinoatrial rate in a compartment distinct from compartments controlled by beta(1)- and beta(2)-adrenoceptors. PDE3 and PDE4 jointly prevent left atrial beta(2)-adrenoceptor-mediated inotropy. Both PDE3 and PDE4 reduce I(Ca-L) responses through beta(1)-adrenoceptors but the PDE3 component is unrelated to inotropy. PDE3 blunts both ventricular inotropic and I(Ca-L) responses through beta(2)-adrenoceptors.
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Affiliation(s)
- Torsten Christ
- Department of Pharmacology, Dresden University of Technology, Dresden, Germany
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20
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Abstract
Triggered activity in cardiac muscle and intracellular Ca2+ have been linked in the past. However, today not only are there a number of cellular proteins that show clear Ca2+ dependence but also there are a number of arrhythmias whose mechanism appears to be linked to Ca2+-dependent processes. Thus we present a systematic review of the mechanisms of Ca2+ transport (forward excitation-contraction coupling) in the ventricular cell as well as what is known for other cardiac cell types. Second, we review the molecular nature of the proteins that are involved in this process as well as the functional consequences of both normal and abnormal Ca2+ cycling (e.g., Ca2+ waves). Finally, we review what we understand to be the role of Ca2+ cycling in various forms of arrhythmias, that is, those associated with inherited mutations and those that are acquired and resulting from reentrant excitation and/or abnormal impulse generation (e.g., triggered activity). Further solving the nature of these intricate and dynamic interactions promises to be an important area of research for a better recognition and understanding of the nature of Ca2+ and arrhythmias. Our solutions will provide a more complete understanding of the molecular basis for the targeted control of cellular calcium in the treatment and prevention of such.
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Affiliation(s)
- Henk E D J Ter Keurs
- Department of Medicine, Physiology and Biophysics, University of Calgary, Alberta, Canada
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21
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Contreras L, Gomez-Puertas P, Iijima M, Kobayashi K, Saheki T, Satrústegui J. Ca2+ Activation kinetics of the two aspartate-glutamate mitochondrial carriers, aralar and citrin: role in the heart malate-aspartate NADH shuttle. J Biol Chem 2007; 282:7098-106. [PMID: 17213189 DOI: 10.1074/jbc.m610491200] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ca(2+) regulation of the Ca(2+) binding mitochondrial carriers for aspartate/glutamate (AGCs) is provided by their N-terminal extensions, which face the intermembrane space. The two mammalian AGCs, aralar and citrin, are members of the malate-aspartate NADH shuttle. We report that their N-terminal extensions contain up to four pairs of EF-hand motifs plus a single vestigial EF-hand, and have no known homolog. Aralar and citrin contain one fully canonical EF-hand pair and aralar two additional half-pairs, in which a single EF-hand is predicted to bind Ca(2+). Shuttle activity in brain or skeletal muscle mitochondria, which contain aralar as the major AGC, is activated by Ca(2+) with S(0.5) values of 280-350 nm; higher than those obtained in liver mitochondria (100-150 nm) that contain citrin as the major AGC. We have used aralar- and citrin-deficient mice to study the role of the two isoforms in heart, which expresses both AGCs. The S(0.5) for Ca(2+) activation of the shuttle in heart mitochondria is about 300 nm, and it remains essentially unchanged in citrin-deficient mice, although it undergoes a drastic reduction to about 100 nm in aralar-deficient mice. Therefore, aralar and citrin, when expressed as single isoforms in heart, confer differences in Ca(2+) activation of shuttle activity, probably associated with their structural differences. In addition, the results reveal that the two AGCs fully account for shuttle activity in mouse heart mitochondria and that no other glutamate transporter can replace the AGCs in this pathway.
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Affiliation(s)
- Laura Contreras
- Departamento de Biología Molecular, Universidad Autónoma de Madrid, C.S.I.C., 28049 Madrid, Spain
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22
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Bootman MD, Higazi DR, Coombes S, Roderick HL. Calcium signalling during excitation-contraction coupling in mammalian atrial myocytes. J Cell Sci 2007; 119:3915-25. [PMID: 16988026 DOI: 10.1242/jcs.03223] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Atrial cardiomyocytes make an important contribution to the refilling of ventricles with blood, which enhances the subsequent ejection of blood from the heart. The dependence of cardiac function on the contribution of atria becomes increasingly important with age and exercise. We know much less about the calcium signals that link electrical depolarisation to contraction within atrial myocytes in comparison with ventricular myocytes. Nevertheless, recent work has shed new light on calcium signalling in atrial cells. At an ultrastructural level, atrial and ventricular myocytes have many similarities. However, a few key structural differences, in particular the lack of transverse tubules (;T-tubules') in atrial myocytes, make these two cell types display vastly different calcium patterns in response to depolarisation. The lack of T-tubules in atrial myocytes means that depolarisation provokes calcium signals that largely originate around the periphery of the cells. To engage the contractile machinery, the calcium signal must propagate centripetally deeper into the cells. This inward movement of calcium is ultimately controlled by hormones that can promote or decrease calcium release within the myocytes. Enhanced centripetal movement of calcium in atrial myocytes leads to increased contraction and a more substantial contribution to blood pumping. The calcium signalling paradigm within atrial cells applies to other cardiac cell types that also do not express T-tubules, such as neonatal ventricular myocytes, and Purkinje cells that aid in the spread of electrical depolarisation. Furthermore, during heart failure ventricular myocytes progressively lose their regular T-tubule expression, and their pattern of response resembles that of atrial cells.
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Affiliation(s)
- Martin D Bootman
- Laboratory of Molecular Signalling, The Babraham Institute, Babraham, Cambridge, CB2 4AT, UK.
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Franzini-Armstrong C, Protasi F, Tijskens P. The Assembly of Calcium Release Units in Cardiac Muscle. Ann N Y Acad Sci 2006; 1047:76-85. [PMID: 16093486 DOI: 10.1196/annals.1341.007] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Calcium release units (CRUs) are constituted of specialized junctional domains of the sarcoplasmic reticulum (jSR) that bear calcium release channels, also called ryanodine receptors (RyRs). In cardiac muscle, CRUs come in three subtypes that differ in geometry, but have common molecular components. Peripheral couplings are formed by a junction of the jSR with the plasmalemma; dyads occur where the jSR is associated with transverse (T)-tubules; corbular SR is a jSR domain that is located within the cells and bears RyRs but does not associate with either plasmalemma or T-tubules. Using transmission electron microscopy, this study followed the formation of CRUs and their accrual of four components: the L-type channel dihydropyridine receptors (DHPRs) of plasmalemma/T-tubules; the RyRs of jSR; triadin (Tr) and junctin (JnC), two homologous components of the jSR membrane; and calsequestrin (CSQ), the internal calcium binding proteins. During differentiation, peripheral couplings are formed first and the others follow. RyRs and DHPRs are targeted to subdomains of the CRUs that face each other and are acquired in a concerted manner. Overexpressions of either junction (JnC or Tr) and of CSQ, singly or in conjunction, shed light on the specific role of JnC in the structural development, organization, and maintenance of jSR cisternae and on the independent synthetic pathways and targeting of JnC and CSQ. In addition, the structural cues provided by the overexpression models allow us to define sequential steps in the synthetic pathway for JnC and CSQ and their targeting to the CRUs of differentiating myocardium.
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Affiliation(s)
- Clara Franzini-Armstrong
- Department of Cell and Developmental Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
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Woo SH, Cleemann L, Morad M. Diversity of atrial local Ca2+ signalling: evidence from 2-D confocal imaging in Ca2+-buffered rat atrial myocytes. J Physiol 2005; 567:905-21. [PMID: 16020459 PMCID: PMC1474227 DOI: 10.1113/jphysiol.2005.092270] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Atrial myocytes, lacking t-tubules, have two functionally separate groups of ryanodine receptors (RyRs): those at the periphery colocalized with dihydropyridine receptors (DHPRs), and those at the cell interior not associated with DHPRs. We have previously shown that the Ca(2+) current (I(Ca))-gated central Ca(2+) release has a fast component that is followed by a slower and delayed rising phase. The mechanisms that regulate the central Ca(2+) releases remain poorly understood. The fast central release component is highly resistant to dialysed Ca(2+) buffers, while the slower, delayed component is completely suppressed by such exogenous buffers. Here we used dialysis of Ca(2+) buffers (EGTA) into voltage-clamped rat atrial myocytes to isolate the fast component of central Ca(2+) release and examine its properties using rapid (240 Hz) two-dimensional confocal Ca(2+) imaging. We found two populations of rat atrial myocytes with respect to the ratio of central to peripheral Ca(2+) release (R(c/p)). In one population ('group 1', approximately 60% of cells), R(c/p) converged on 0.2, while in another population ('group 2', approximately 40%), R(c/p) had a Gaussian distribution with a mean value of 0.625. The fast central release component of group 2 cells appeared to result from in-focus Ca(2+) sparks on activation of I(Ca). In group 1 cells intracellular membranes associated with t-tubular structures were never seen using short exposures to membrane dyes. In most of the group 2 cells, a faint intracellular membrane staining was observed. Quantification of caffeine-releasable Ca(2+) pools consistently showed larger central Ca(2+) stores in group 2 and larger peripheral stores in group 1 cells. The R(c/p) was larger at more positive and negative voltages in group 1 cells. In contrast, in group 2 cells, the R(c/p) was constant at all voltages. In group 1 cells the gain of peripheral Ca(2+) release sites (Delta[Ca(2+)]/I(Ca)) was larger at -30 than at +20 mV, but significantly dampened at the central sites. On the other hand, the gains of peripheral and central Ca(2+) releases in group 2 cells showed no voltage dependence. Surprisingly, the voltage dependence of the fast central release component was bell-shaped and similar to that of I(Ca) in both cell groups. Removal of extracellular Ca(2+) or application of Ni(2+) (5 mM) suppressed equally I(Ca) and Ca(2+) release from the central release sites at +60 mV. Depolarization to +100 mV, where I(Ca) is absent and the Na(+)-Ca(2+) exchanger (NCX) acts in reverse mode, did not trigger the fast central Ca(2+) releases in either group, but brief reduction of [Na(+)](o) to levels equivalent to [Na(+)](i) facilitated fast peripheral and central Ca(2+) releases in group 2 myocytes, but not in group 1 myocytes. In group 2 cells, long-lasting (> 1 min) exposures to caffeine (10 mM) or ryanodine (20 microM) significantly suppressed I(Ca)-triggered central and peripheral Ca(2+) releases. Our data suggest significant diversity of local Ca(2+) signalling in rat atrial myocytes. In one group, I(Ca)-triggered peripheral Ca(2+) release propagates into the interior triggering central Ca(2+) release with significant delay. In a second group of myocytes I(Ca) triggers a significant number of central sites as rapidly and effectively as the peripheral sites, thereby producing more synchronized Ca(2+) releases throughout the myocytes. The possible presence of vestigial t-tubules and larger Ca(2+) content of central sarcoplasmic reticulum (SR) in group 2 cells may be responsible for the rapid and strong activation of central release of Ca(2+) in this subset of atrial myocytes.
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Affiliation(s)
- Sun-Hee Woo
- Department of Pharmacology, Georgetown University Medical Center, Washington, DC 20057, USA
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Scriven DRL, Klimek A, Asghari P, Bellve K, Moore EDW. Caveolin-3 is adjacent to a group of extradyadic ryanodine receptors. Biophys J 2005; 89:1893-901. [PMID: 15980179 PMCID: PMC1366692 DOI: 10.1529/biophysj.105.064212] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Caveolae are present in almost all cells and concentrate a wide variety of signaling molecules, receptors, transporters, and ion pumps. We have investigated the distribution of the ryanodine receptor, the Na(+)/Ca(2+) exchanger, the predominant Na(+) channel isoform rH1, and the L-type calcium channel, Ca(v)1.2, relative to the muscle-specific caveolin isoform, caveolin-3, in adult rat ventricular myocytes. Three-dimensional immunofluorescence images were deconvolved and analyzed. Caveolin-3 colocalizes with all of these molecules at the surface of the cell, but there is no significant colocalization between caveolin-3 and either the Na(+)/Ca(2+) exchanger or the Na(+) channel in the cell interior. The distribution of the surface colocalization indicates that the caveolae that colocalize with each molecule form distinct populations. This organization indicates that there are multiple populations of caveolae separable by location and occupants. In the interior of the cell, caveolin-3 shows a marked colocalization with a population of ryanodine receptors that are separate from those within the dyad. Because of their location, the signaling molecules contained within these caveolae may have preferred access to the neighboring nondyadic ryanodine receptors.
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Affiliation(s)
- David R L Scriven
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
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Kirk MM, Izu LT, Chen-Izu Y, McCulle SL, Wier WG, Balke CW, Shorofsky SR. Role of the transverse-axial tubule system in generating calcium sparks and calcium transients in rat atrial myocytes. J Physiol 2003; 547:441-51. [PMID: 12562899 PMCID: PMC2342655 DOI: 10.1113/jphysiol.2002.034355] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2002] [Accepted: 11/27/2002] [Indexed: 11/08/2022] Open
Abstract
Cardiac atrial cells lack a regular system of transverse tubules like that in cardiac ventricular cells. Nevertheless, many atrial cells do possess an irregular internal transverse-axial tubular system (TATS). To investigate the possible role of the TATS in excitation-contraction coupling in atrial myocytes, we visualized the TATS (labelled with the fluorescent indicator, Di-8-ANEPPS) simultaneously with Ca2+ transients and/or Ca2+ sparks (fluo-4). In confocal transverse linescan images of field-stimulated cells, whole-cell Ca2+ transients had two morphologies: 'U-shaped' transients and irregular or 'W-shaped' transients with a varying number of points of origin of the Ca2+ transient. About half (54 %, n =289 cells, 13 animals) of the cells had a TATS. Cells with TATS had a larger mean diameter (13.2 +/- 2.8 microm) than cells without TATS (11.7 +/- 2.0 microm) and were more common in the left atrium (n = 206 cells; left atrium: 76 with TATS, 30 without TATS; right atrium: 42 with TATS, 58 without TATS). Simultaneous measurement of Ca2+ sparks and sarcolemmal structures showed that cells without TATS had U-shaped transients that started at the cell periphery, and cells with TATS had W-shaped transients that began simultaneously at the cell periphery and the TATS. Most (82 out of 102 from 31 cells) 'spontaneous' (non-depolarized) Ca2+ sparks occurred within 1 microm of a sarcolemmal structure (cell periphery or TATS), and 33 % occurred within 1 pixel (0.125 microm). We conclude that the presence of a sarcolemmal membrane either at the cell periphery or in the TATS in close apposition to the sarcoplasmic reticulum is required for the initiation of an evoked Ca2+ transient and for spontaneous Ca2+ sparks.
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Affiliation(s)
- Malcolm M Kirk
- Department of Medicine, University of Maryland School of Medicine, Baltimore, MD 21201-1541, USA
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Brette F, Komukai K, Orchard CH. Validation of formamide as a detubulation agent in isolated rat cardiac cells. Am J Physiol Heart Circ Physiol 2002; 283:H1720-8. [PMID: 12234828 DOI: 10.1152/ajpheart.00347.2002] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Kawai M, Hussain M, and Orchard CH. Am J Heart Circ Physiol 277: H603-H609, 1999 developed a technique to detubulate rat ventricular myocytes using formamide and showed that detubulation results in a decrease in cell capacitance, Ca(2+) current density, and Ca(2+) transient amplitude. We have investigated the mechanism of this detubulation and possible direct effects of formamide. Staining ventricular cells with di-8-ANEPPS showed that the t tubule membranes remain inside the cell after detubulation; trapping of FITC-labeled dextran within the t tubules showed that detubulation occurs during formamide washout and that the t tubules appear to reseal within the cell. Detubulation had no effect on the microtubule network but resulted in loss of synchronous Ca(2+) release on electrical stimulation. In contrast, formamide treatment of atrial cells did not significantly change cell capacitance, Ca(2+) current amplitude, action potential configuration, the Ca(2+) transient or the response of the Ca(2+) transient to isoprenaline. We conclude that formamide washout induces detubulation of single rat ventricular myocytes, leaving the t tubules within the cell, but without direct effects on cell proteins that might alter cell function.
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Affiliation(s)
- Fabien Brette
- School of Biomedical Sciences, University of Leeds, United Kingdom
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