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Parra V, Monaco G, Morciano G, Santulli G. Editorial: Mitochondrial remodeling and dynamic inter-organellar contacts in cardiovascular physiopathology-Volume II. Front Cell Dev Biol 2023; 11:1240207. [PMID: 37427376 PMCID: PMC10325657 DOI: 10.3389/fcell.2023.1240207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Accepted: 06/16/2023] [Indexed: 07/11/2023] Open
Affiliation(s)
- Valentina Parra
- Advanced Center of Chronic Diseases (ACCDiS), Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Giovanni Monaco
- Center for Innovation and Stimulation of Drug Discovery (CISTIM), Leuven, Belgium
| | - Giampaolo Morciano
- Section of Experimental Medicine, Laboratory for Technologies of Advanced Therapies (LTTA), Department of Medical Sciences, University of Ferrara, Ferrara, Italy
- Maria Cecilia Hospital, GVM Care and Research, Cotignola, Italy
| | - Gaetano Santulli
- Division of Cardiology, Department of Medicine, Albert Einstein College of Medicine, Wilf Family Cardiovascular Research Institute and Einstein Institute for Aging Research, New York, NY, United States
- Department of Molecular Pharmacology, Einstein-Sinai Diabetes Research Center (ES-DRC), Fleischer Institute for Diabetes and Metabolism (FIDAM), Montefiore University Hospital, New York, NY, United States
- International Translational Research and Medical Education Academic Research Unit (ITME), Department of Advanced Biomedical Sciences, “Federico II” University, Naples, Italy
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Pedriali G, Ramaccini D, Bouhamida E, Wieckowski MR, Giorgi C, Tremoli E, Pinton P. Perspectives on mitochondrial relevance in cardiac ischemia/reperfusion injury. Front Cell Dev Biol 2022; 10:1082095. [PMID: 36561366 PMCID: PMC9763599 DOI: 10.3389/fcell.2022.1082095] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Accepted: 11/24/2022] [Indexed: 12/12/2022] Open
Abstract
Cardiovascular disease is the most common cause of death worldwide and in particular, ischemic heart disease holds the most considerable position. Even if it has been deeply studied, myocardial ischemia-reperfusion injury (IRI) is still a side-effect of the clinical treatment for several heart diseases: ischemia process itself leads to temporary damage to heart tissue and obviously the recovery of blood flow is promptly required even if it worsens the ischemic injury. There is no doubt that mitochondria play a key role in pathogenesis of IRI: dysfunctions of these important organelles alter cell homeostasis and survival. It has been demonstrated that during IRI the system of mitochondrial quality control undergoes alterations with the disruption of the complex balance between the processes of mitochondrial fusion, fission, biogenesis and mitophagy. The fundamental role of mitochondria is carried out thanks to the finely regulated connection to other organelles such as plasma membrane, endoplasmic reticulum and nucleus, therefore impairments of these inter-organelle communications exacerbate IRI. This review pointed to enhance the importance of the mitochondrial network in the pathogenesis of IRI with the aim to focus on potential mitochondria-targeting therapies as new approach to control heart tissue damage after ischemia and reperfusion process.
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Affiliation(s)
- Gaia Pedriali
- Maria Cecilia Hospital, GVM Care and Research, Cotignola, Italy
| | | | - Esmaa Bouhamida
- Maria Cecilia Hospital, GVM Care and Research, Cotignola, Italy
| | - Mariusz R. Wieckowski
- Laboratory of Mitochondrial Biology and Metabolism, Nencki Institute of Experimental Biology, Warsaw, Poland
| | - Carlotta Giorgi
- Laboratory for Technologies of Advanced Therapies (LTTA), Department of Medical Science, Section of Experimental Medicine, University of Ferrara, Ferrara, Italy
| | - Elena Tremoli
- Maria Cecilia Hospital, GVM Care and Research, Cotignola, Italy,*Correspondence: Paolo Pinton, ; Elena Tremoli,
| | - Paolo Pinton
- Maria Cecilia Hospital, GVM Care and Research, Cotignola, Italy,Laboratory for Technologies of Advanced Therapies (LTTA), Department of Medical Science, Section of Experimental Medicine, University of Ferrara, Ferrara, Italy,*Correspondence: Paolo Pinton, ; Elena Tremoli,
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Connexins in the Heart: Regulation, Function and Involvement in Cardiac Disease. Int J Mol Sci 2021; 22:ijms22094413. [PMID: 33922534 PMCID: PMC8122935 DOI: 10.3390/ijms22094413] [Citation(s) in RCA: 57] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 04/12/2021] [Accepted: 04/20/2021] [Indexed: 12/20/2022] Open
Abstract
Connexins are a family of transmembrane proteins that play a key role in cardiac physiology. Gap junctional channels put into contact the cytoplasms of connected cardiomyocytes, allowing the existence of electrical coupling. However, in addition to this fundamental role, connexins are also involved in cardiomyocyte death and survival. Thus, chemical coupling through gap junctions plays a key role in the spreading of injury between connected cells. Moreover, in addition to their involvement in cell-to-cell communication, mounting evidence indicates that connexins have additional gap junction-independent functions. Opening of unopposed hemichannels, located at the lateral surface of cardiomyocytes, may compromise cell homeostasis and may be involved in ischemia/reperfusion injury. In addition, connexins located at non-canonical cell structures, including mitochondria and the nucleus, have been demonstrated to be involved in cardioprotection and in regulation of cell growth and differentiation. In this review, we will provide, first, an overview on connexin biology, including their synthesis and degradation, their regulation and their interactions. Then, we will conduct an in-depth examination of the role of connexins in cardiac pathophysiology, including new findings regarding their involvement in myocardial ischemia/reperfusion injury, cardiac fibrosis, gene transcription or signaling regulation.
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Connexin 43 Deficiency Is Associated with Reduced Myocardial Scar Size and Attenuated TGFβ1 Signaling after Transient Coronary Occlusion in Conditional Knock-Out Mice. Biomolecules 2020; 10:biom10040651. [PMID: 32340244 PMCID: PMC7226061 DOI: 10.3390/biom10040651] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 04/15/2020] [Accepted: 04/20/2020] [Indexed: 12/20/2022] Open
Abstract
Previous studies demonstrated a reduction in myocardial scar size in heterozygous Cx43+/- mice subjected to permanent coronary occlusion. However, patients presenting with ST segment elevation myocardial infarction often undergo rapid coronary revascularization leading to prompt restoration of coronary flow. Therefore, we aimed to assess changes in scar size and left ventricular remodeling following transient myocardial ischemia (45 min) followed by 14 days of reperfusion using Cx43fl/fl (controls) and Cx43Cre-ER(T)/fl inducible knock-out (Cx43 content: 50%) mice treated with vehicle or 4-hydroxytamoxifen (4-OHT) to induce a Cre-ER(T)-mediated global deletion of the Cx43 floxed allele. The scar area (picrosirius red), measured 14 days after transient coronary occlusion, was similarly reduced in both vehicle and 4-OHT-treated Cx43Cre-ER(T)/fl mice, compared to Cx43fl/fl animals, having normal Cx43 levels (15.78% ± 3.42% and 16.54% ± 2.31% vs. 25.40% ± 3.14% and 22.43% ± 3.88% in vehicle and 4-OHT-treated mice, respectively, p = 0.027). Left ventricular dilatation was significantly attenuated in both Cx43-deficient groups (p = 0.037 for left ventricular end-diastolic diameter). These protective effects were correlated with an attenuated enhancement in pro-transforming growth factor beta 1 (TGFβ1) expression after reperfusion. In conclusion, our data demonstrate that Cx43 deficiency induces a protective effect on scar formation after transient coronary occlusion in mice, an effect associated with reduced left ventricular remodeling and attenuated enhancement in pro-TGFβ1 expression.
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Trevisan AM, Cogliati B, Homem AR, Aloiav TPA, de Aquino N, Moreira JM, Reno LDC, Naumann AM, Galvão FHF, Andraus W, D'Albuquerque LAC. The liver injury following ischemia and reperfusion is worse in experimental knockout heterozygote mouse model for expression of connexin 431. Acta Cir Bras 2019; 34:e201901003. [PMID: 31851211 PMCID: PMC6912844 DOI: 10.1590/s0102-865020190100000003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 08/12/2019] [Accepted: 09/16/2019] [Indexed: 01/01/2023] Open
Abstract
PURPOSE To evaluate that Connexin (Cx43) plays a role in lesions after hepatic ischemia/reperfusion (IR) injury. METHODS We use Cx43 deficient model (heterozygotes mice) and compared to a wild group. The groups underwent 1 hour ischemia and 24 hours reperfusion. The heterozygote genotype was confirmed by PCR. We analyzed the hepatic enzymes (AST, ALT, GGT) and histology. RESULTS The mice with Cx43 deficiency showed an ALT mean value of 4166 vs. 307 in the control group (p<0.001); AST mean value of 7231 vs. 471 in the control group (p<0.001); GGT mean value of 9.4 vs. 1.7 in the control group (p=0.001); histology showed necrosis and inflammation in the knockout group. CONCLUSIONS This research demonstrated that the deficiency of Cx43 worses the prognosis for liver injury. The topic is a promising target for therapeutics advancements in liver diseases and procedures.
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Affiliation(s)
- Alexandre Maximiliano Trevisan
- Fellow PhD degree and MSc degree, Postgraduate Program in
Medicine Science in Gastroenterology, Department of Gastroenterology, School of
Medicine, Medical Investigation Laboratory (LIM 37), Universidade de São Paulo
(USP), Brazil. Technical procedures, acquisition of data, statistical analysis,
manuscript writing
| | - Bruno Cogliati
- PhD, Department of Pathology, School of Veterinary Medicine and
Animal Science, USP, Sao Paulo-SP, Brazil. Technical procedures
| | - Adriana Ribeiro Homem
- PhD, Department of Gastroenterology, School of Medicine,
Medical Investigation Laboratory (LIM 37), USP, Sao Paulo-SP, Brazil. Manuscript
writing
| | | | - Nelson de Aquino
- Fellow Master degree, Postgraduate Program in Medicine Surgical
Gastroenterology, School of Medicine, USP, Sao Paulo-SP, Brazil. Statistical
analysis, manuscript writing
| | - Jairo Marques Moreira
- Biologist, Hospital Albert Einstein, Sao Paulo-SP, Brazil.
Technical procedures, acquisition of data
| | - Leonardo da Cruz Reno
- Fellow Master degree, Postgraduate Program in Medicine
Surgical Gastroenterology, School of Medicine, USP, Sao Paulo-SP, Brazil.
Technical procedures, acquisition of data, manuscript writing
| | - Alexandre Moulin Naumann
- Fellow Master degree, Postgraduate Program in Medicine
Surgical Gastroenterology, School of Medicine, USP, Sao Paulo-SP, Brazil.
Technical procedures, acquisition of data, manuscript writing
| | - Flavio Henrique Ferreira Galvão
- Assistant Professor, Liver and Gastrointestinal Transplant
Division, Department of Gastroenterology, School of Medicine, Coordinator,
Medical Investigation Laboratory (LIM 37), USP, Sao Paulo-SP, Brazil. Surgical
procedures, manuscript writing, critical revision
| | - Wellington Andraus
- Assistant Professor, Coordinator, Liver and Gastrointestinal
Transplant Division, Department of Gastroenterology, School of Medicine, Medical
Investigation Laboratory (LIM 37), USP, Sao Paulo-SP, Brazil. Surgical
procedures, manuscript writing, critical revision
| | - Luiz Augusto Carneiro D'Albuquerque
- Full Professor, Chairman, Liver and Gastrointestinal Transplant
Division, Department of Gastroenterology, School of Medicine, Medical
Investigation Laboratory (LIM 37), USP, Sao Paulo-SP, Brazil. Conception and
design of the study, manuscript writing, critical revision
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Valls-Lacalle L, Barba I, Miró-Casas E, Ruiz-Meana M, Rodríguez-Sinovas A, García-Dorado D. Selective Inhibition of Succinate Dehydrogenase in Reperfused Myocardium with Intracoronary Malonate Reduces Infarct Size. Sci Rep 2018; 8:2442. [PMID: 29402957 PMCID: PMC5799359 DOI: 10.1038/s41598-018-20866-4] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Accepted: 01/25/2018] [Indexed: 02/07/2023] Open
Abstract
Inhibition of succinate dehydrogenase (SDH) with malonate during reperfusion reduces infarct size in isolated mice hearts submitted to global ischemia. However, malonate has toxic effects that preclude its systemic administration in animals. Here we investigated the effect of intracoronary malonate on infarct size in pigs submitted to transient coronary occlusion. Under baseline conditions, 50 mmol/L of intracoronary disodium malonate, but not lower concentrations, transiently reduced systolic segment shortening in the region perfused by the left anterior descending coronary artery (LAD) in open-chest pigs. To assess the effects of SDH inhibition on reperfusion injury, saline or malonate 10 mmol/L were selectively infused into the area at risk in 38 animals submitted to ischemia-reperfusion. Malonate improved systolic shortening in the area at risk two hours after 15 min of ischemia (0.18 ± 0.07 vs 0.00 ± 0.01 a.u., p = 0.025, n = 3). In animals submitted to 40 min of ischemia, malonate reduced reactive oxygen species production (MitoSOX staining) during initial reperfusion and limited infarct size (36.46 ± 5.35 vs 59.62 ± 4.00%, p = 0.002, n = 11), without modifying reperfusion arrhythmias. In conclusion, inhibition of SDH with intracoronary malonate during early reperfusion limits reperfusion injury and infarct size in pigs submitted to transient coronary occlusion without modifying reperfusion arrhythmias or contractile function in distant myocardium.
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Affiliation(s)
- Laura Valls-Lacalle
- Cardiovascular Diseases Research Group, Department of Cardiology, Vall d'Hebron University Hospital and Research Institute, Universitat Autònoma de Barcelona, Departament de Medicina, Barcelona, Spain.,Centro de Investigación Biomédica en Red Enfermedades Cardiovasculares (CIBERCV), Instituto de Salud Carlos III, Madrid, Spain
| | - Ignasi Barba
- Cardiovascular Diseases Research Group, Department of Cardiology, Vall d'Hebron University Hospital and Research Institute, Universitat Autònoma de Barcelona, Departament de Medicina, Barcelona, Spain.,Centro de Investigación Biomédica en Red Enfermedades Cardiovasculares (CIBERCV), Instituto de Salud Carlos III, Madrid, Spain
| | - Elisabet Miró-Casas
- Cardiovascular Diseases Research Group, Department of Cardiology, Vall d'Hebron University Hospital and Research Institute, Universitat Autònoma de Barcelona, Departament de Medicina, Barcelona, Spain.,Centro de Investigación Biomédica en Red Enfermedades Cardiovasculares (CIBERCV), Instituto de Salud Carlos III, Madrid, Spain
| | - Marisol Ruiz-Meana
- Cardiovascular Diseases Research Group, Department of Cardiology, Vall d'Hebron University Hospital and Research Institute, Universitat Autònoma de Barcelona, Departament de Medicina, Barcelona, Spain.,Centro de Investigación Biomédica en Red Enfermedades Cardiovasculares (CIBERCV), Instituto de Salud Carlos III, Madrid, Spain
| | - Antonio Rodríguez-Sinovas
- Cardiovascular Diseases Research Group, Department of Cardiology, Vall d'Hebron University Hospital and Research Institute, Universitat Autònoma de Barcelona, Departament de Medicina, Barcelona, Spain. .,Centro de Investigación Biomédica en Red Enfermedades Cardiovasculares (CIBERCV), Instituto de Salud Carlos III, Madrid, Spain.
| | - David García-Dorado
- Cardiovascular Diseases Research Group, Department of Cardiology, Vall d'Hebron University Hospital and Research Institute, Universitat Autònoma de Barcelona, Departament de Medicina, Barcelona, Spain. .,Centro de Investigación Biomédica en Red Enfermedades Cardiovasculares (CIBERCV), Instituto de Salud Carlos III, Madrid, Spain.
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Boengler K, Bulic M, Schreckenberg R, Schlüter K, Schulz R. The gap junction modifier ZP1609 decreases cardiomyocyte hypercontracture following ischaemia/reperfusion independent from mitochondrial connexin 43. Br J Pharmacol 2017; 174:2060-2073. [PMID: 28369703 PMCID: PMC5466543 DOI: 10.1111/bph.13804] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Revised: 03/13/2017] [Accepted: 03/16/2017] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND AND PURPOSE Dysregulation of gap junction-mediated cell coupling contributes to development of arrhythmias and myocardial damage after ischaemia/reperfusion (I/R). Connexin 43 (Cx43) is present at ventricular gap junctions and also in the mitochondria of cardiomyocytes. The dipeptide (2S, 4R)-1-(2-aminoacetyl)-4-benzamidopyrrolidine-2-carboxylic acid (ZP1609) has antiarrhythmic properties and reduces infarct size when given at reperfusion. However, it is unclear, whether ZP1609 targets Cx43-containing mitochondria and affects cardiomyocyte hypercontracture following I/R. EXPERIMENTAL APPROACH We studied the effects of ZP1609 on the function of murine sub-sarcolemmal mitochondria (SSM, containing Cx43) and interfibrillar mitochondria (IFM, lacking Cx43). Murine isolated cardiomyocytes were subjected to simulated I/R without and with ZP1609 (applied during I/R or at the onset of reperfusion only), and the number of cardiomyocytes undergoing hypercontracture was quantified. Biochemical pathways targeted by ZP1609 in cardiomyocytes were analysed. KEY RESULTS ZP1609 inhibited ADP-stimulated respiration and ATP production in SSM and IFM. ROS formation and calcium retention capacities in SSM and IFM were not affected by ZP1609, whereas potassium uptake was enhanced in IFM. The number of rod-shaped cardiomyocytes was increased by ZP1609 (10 μM) when administered either during I/R or reperfusion. ZP1609 altered the phosphorylation of proteins contributing to the protection against I/R injury. CONCLUSIONS AND IMPLICATIONS ZP1609 reduced mitochondrial respiration and ATP production, but enhanced potassium uptake of IFM. Additionally, ZP1609 reduced the extent of cardiomyocytes undergoing hypercontracture following I/R. The protective effect was independent of mitochondrial Cx43, as ZP1609 exerts its effects in Cx43-containing SSM and Cx43-lacking IFM.
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Affiliation(s)
- Kerstin Boengler
- Physiologisches InstitutJustus‐Liebig‐Universität GiessenGiessenGermany
| | - Marko Bulic
- Physiologisches InstitutJustus‐Liebig‐Universität GiessenGiessenGermany
| | | | | | - Rainer Schulz
- Physiologisches InstitutJustus‐Liebig‐Universität GiessenGiessenGermany
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Rodríguez-Sinovas A, Ruiz-Meana M, Denuc A, García-Dorado D. Mitochondrial Cx43, an important component of cardiac preconditioning. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017. [PMID: 28642043 DOI: 10.1016/j.bbamem.2017.06.011] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Connexin 43 (Cx43) forms gap junction channels that are essential for the propagation of electrical depolarization in cardiomyocytes, but also with important roles in the pathophysiology of reperfusion injury. However, more recent studies have shown that Cx43 has also important functions independent from intercellular communication between adjacent cardiomyocytes. Some of these actions have been related to the presence of Cx43 in the mitochondria of these cells (mitoCx43). The functions of mitoCx43 have not been completely elucidated, but there is strong evidence indicating that mitoCx43 modulates mitochondrial respiration at respiratory complex I, production of radical oxygen species and ATP synthesis. These functions of mitoCx43 modulate mitochondrial and cellular tolerance to reperfusion after prolonged ischemia and are necessary for the cardioprotective effect of ischemic preconditioning. In the present review article we discuss available knowledge on these functions of mitoCx43 in relation to reperfusion injury, the molecular mechanisms involved and explore the possibility that mitoCx43 may constitute a new pharmacological target in patients with ST-segment elevation myocardial infarction (STEMI). This article is part of a Special Issue entitled: Gap Junction Proteins edited by Jean Claude Herve.
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Affiliation(s)
- Antonio Rodríguez-Sinovas
- Cardiovascular Diseases Research Group, Department of Cardiology, Vall d'Hebron University Hospital and Research Institute, Universitat Autònoma de Barcelona, Barcelona, Spain; Centro de Investigación Biomédica en Red sobre Enfermedades Cardiovasculares (CIBERCV), Spain
| | - Marisol Ruiz-Meana
- Cardiovascular Diseases Research Group, Department of Cardiology, Vall d'Hebron University Hospital and Research Institute, Universitat Autònoma de Barcelona, Barcelona, Spain; Centro de Investigación Biomédica en Red sobre Enfermedades Cardiovasculares (CIBERCV), Spain
| | - Amanda Denuc
- Cardiovascular Diseases Research Group, Department of Cardiology, Vall d'Hebron University Hospital and Research Institute, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - David García-Dorado
- Cardiovascular Diseases Research Group, Department of Cardiology, Vall d'Hebron University Hospital and Research Institute, Universitat Autònoma de Barcelona, Barcelona, Spain; Centro de Investigación Biomédica en Red sobre Enfermedades Cardiovasculares (CIBERCV), Spain.
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Guerrero-Orriach JL, Escalona Belmonte JJ, Ramirez Fernandez A, Ramirez Aliaga M, Rubio Navarro M, Cruz Mañas J. Cardioprotection with halogenated gases: how does it occur? Drug Des Devel Ther 2017; 11:837-849. [PMID: 28352158 PMCID: PMC5358986 DOI: 10.2147/dddt.s127916] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Numerous studies have studied the effect of halogenated agents on the myocardium, highlighting the beneficial cardiac effect of the pharmacological mechanism (preconditioning and postconditioning) when employed before and after ischemia in patients with ischemic heart disease. Anesthetic preconditioning is related to the dose-dependent signal, while the degree of protection is related to the concentration of the administered drug and the duration of the administration itself. Triggers for postconditioning and preconditioning might have numerous pathways in common; mitochondrial protection and a decrease in inflammatory mediators could be the major biochemical elements. Several pathways have been identified, including attenuation of NFκB activation and reduced expression of TNFα, IL-1, intracellular adhesion molecules, eNOS, the hypercontraction reduction that follows reperfusion, and antiapoptotic activating kinases (Akt, ERK1/2). It appears that the preconditioning and postconditioning triggers have numerous similar paths. The key biochemical elements are protection of the mitochondria and reduction in inflammatory mediators, both of which are developed in various ways. We have studied this issue, and have published several articles on cardioprotection with halogenated gases. Our results confirm greater cardioprotection through myocardial preconditioning in patients anesthetized with sevoflurane compared with propofol, with decreasing levels of troponin and N-terminal brain natriuretic peptide prohormone. The difference between our studies and previous studies lies in the use of sedation with sevoflurane in the postoperative period. The results could be related to a prolonged effect, in addition to preconditioning and postconditioning, which could enhance the cardioprotective effect of sevoflurane in the postoperative period. With this review, we aim to clarify the importance of various mechanisms involved in preconditioning and postconditioning with halogenated gases, as supported by our studies.
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Affiliation(s)
- Jose Luis Guerrero-Orriach
- Department of Cardioanesthesiology, Virgen de la Victoria University Hospital
- Instituto de Investigación Biomédica de Málaga (IBIMA)
- Department of Pharmacology and Pediatrics, University of Malaga, Malaga, Spain
| | | | | | | | | | - Jose Cruz Mañas
- Department of Cardioanesthesiology, Virgen de la Victoria University Hospital
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Gap Junction-associated Na+ Influx Is Involved in the Mediation of Ca2+ Transients in Neonatal Rat Ventricular Myocytes. J Cardiovasc Pharmacol 2015; 66:41-9. [DOI: 10.1097/fjc.0000000000000241] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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11
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Garcia-Dorado D, Rodríguez-Sinovas A, Ruiz-Meana M, Inserte J. Protección contra el daño miocárdico por isquemia-reperfusión en la práctica clínica. Rev Esp Cardiol 2014. [DOI: 10.1016/j.recesp.2014.01.011] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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12
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Morel S, Braunersreuther V, Chanson M, Bouis D, Rochemont V, Foglia B, Pelli G, Sutter E, Pinsky DJ, Mach F, Kwak BR. Endothelial Cx40 limits myocardial ischaemia/reperfusion injury in mice. Cardiovasc Res 2014; 102:329-37. [PMID: 24639196 DOI: 10.1093/cvr/cvu063] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2023] Open
Abstract
AIMS Gap junctions are indispensable for the function of heart and blood vessels by providing electrical coupling and direct cell-to-cell transfer of small signalling molecules. Gap junction channels between neighbouring cells are composed of 12 connexins (Cx). Changes in Cx43 expression, localization, and channel properties in cardiomyocytes contribute to infarction and reperfusion injury of the heart. It is increasingly recognized that deleterious consequences of ischaemia/reperfusion (IR) are modulated by the inflammatory response and endothelial function. The role of the endothelial connexins, i.e. Cx40 and Cx37, in cardiac IR injury is, however, not known. METHODS AND RESULTS Following 30 min ischaemia and 24 h reperfusion, we found a significant increase in myocardial infarct size in mice with endothelial-specific deletion of Cx40 (Cx40del), but not in Cx37-deficient mice. The cardioprotective effect of endothelial Cx40 was associated with a decrease in neutrophil infiltration. Moreover, beneficial effects of endothelial Cx40 were not observed in isolated Langendorff-perfused hearts, suggesting direct involvement of endothelial-leucocyte interactions in the cardiac injury. Single-dose administration of methotrexate, a CD73 activator, reduced infarct size and neutrophil infiltration into the infarcted myocardium in Cx40del but not in control mice. Similar to Cx40del mice, CD73-deficient mice showed increased sensitivity to cardiac IR injury, which could not be conversed by methotrexate. CONCLUSION Endothelial Cx40, but not Cx37, is implicated in resistance of the heart to IR injury by activation of the CD73 pathway. Thus, the Cx40-CD73 axis may represent an interesting target for controlling reperfusion damage associated with revascularization in coronary disease.
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Affiliation(s)
- Sandrine Morel
- Department of Pathology and Immunology, University of Geneva Medical School, CMU, Rue Michel-Servet 1, CH-1211 Geneva 4, Switzerland
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Konopacki J, Bocian R, Kowalczyk T, Kłos-Wojtczak P. The electrical coupling and the hippocampal formation theta rhythm in rats. Brain Res Bull 2014; 107:1-17. [PMID: 24747291 DOI: 10.1016/j.brainresbull.2014.04.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Revised: 04/03/2014] [Accepted: 04/08/2014] [Indexed: 02/05/2023]
Abstract
Gap junctions (GJs) were discovered more than five decades ago, and since that time enormous strides have been made in understanding their structure and function. Despite the voluminous literature concerning the function of GJs, the involvement of these membrane structures in the central mechanisms underlying oscillations and synchrony in the neuronal network is still a matter of intensive debate. This review summarizes what is known concerning the involvement of GJs as electrical synapses in mechanisms underlying the generation of theta band oscillations. The first part of the chapter discusses the role of GJs in mechanisms of oscillations and synchrony. Following this, in vitro, ex vivo, and in vivo experiments concerning the involvement of GJs in the generation of hippocampal formation theta in rats are reviewed.
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Affiliation(s)
- Jan Konopacki
- Department of Neurobiology, The University of Lodz, Poland.
| | - Renata Bocian
- Department of Neurobiology, The University of Lodz, Poland
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Garcia-Dorado D, Rodríguez-Sinovas A, Ruiz-Meana M, Inserte J. Protection against myocardial ischemia-reperfusion injury in clinical practice. ACTA ACUST UNITED AC 2014; 67:394-404. [PMID: 24774733 DOI: 10.1016/j.rec.2014.01.010] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Accepted: 01/22/2014] [Indexed: 12/28/2022]
Abstract
Even when reperfusion therapy is applied as early as possible, survival and quality of life are compromised in a considerable number of patients with ST-segment elevation acute myocardial infarction. Some cell death following transient coronary occlusion occurs during reperfusion, due to poor handling of calcium in the sarcoplasmic reticulum-mitochondria system, calpain activation, oxidative stress, and mitochondrial failure, all promoted by rapid normalization of intracellular pH. Various clinical trials have shown that infarct size can be limited by nonpharmacological strategies--such as ischemic postconditioning and remote ischemic conditioning--or by drugs--such as cyclosporine, insulin, glucagon-like peptide-1 agonists, beta-blockers, or stimulation of cyclic guanosine monophosphate synthesis. However, some clinical studies have yielded negative results, largely due to a lack of consistent preclinical data or a poor design, especially delayed administration. Large-scale clinical trials are therefore necessary, particularly those with primary clinical variables and combined therapies that consider age, sex, and comorbidities, to convert protection against reperfusion injury into a standard treatment for patients with ST-segment elevation acute myocardial infarction.
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Affiliation(s)
- David Garcia-Dorado
- Hospital Universitario e Institut de Recerca Vall d'Hebron, Universitat Autònoma de Barcelona, Barcelona, Spain.
| | - Antonio Rodríguez-Sinovas
- Hospital Universitario e Institut de Recerca Vall d'Hebron, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Marisol Ruiz-Meana
- Hospital Universitario e Institut de Recerca Vall d'Hebron, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Javier Inserte
- Hospital Universitario e Institut de Recerca Vall d'Hebron, Universitat Autònoma de Barcelona, Barcelona, Spain
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Pollard AE, Barr RC. A structural framework for interpretation of four-electrode microimpedance spectra in cardiac tissue. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2014; 2014:6467-6470. [PMID: 25571477 PMCID: PMC4288478 DOI: 10.1109/embc.2014.6945109] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Renewed interest in the four-electrode method for identification of passive electrical properties in cardiac tissue has been sparked by a recognition that measurements made with sensors in close proximity are frequency dependent. Therefore, resolution of four-electrode microimpedance spectra (4EMS) may provide an opportunity for routine identification of passive electrical properties for the interstitial and intracellular compartments using only interstitial access. The present study documents a structural framework in which the tissue resistivity (ρt) and reactivity (xt) that comprise spectra are computed using interstitial and intracellular microimpedance distributions that account for differences in compartment size, anisotropic electrical properties in each compartment and electrode separations. We used this framework to consider 4EMS development with relatively wide (d=1 mm) and fine (d=250 μm) electrode separations and sensors oriented along myocyte axes, across myocyte axes and intermediate between those axes.
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Affiliation(s)
- Andrew E. Pollard
- Department Biomedical Engineering, Cardiac Rhythm Management Laboratory, University of Alabama Birmingham, Birmingham, AL, USA
| | - Roger C. Barr
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
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Webster KA. Mitochondrial membrane permeabilization and cell death during myocardial infarction: roles of calcium and reactive oxygen species. Future Cardiol 2013; 8:863-84. [PMID: 23176689 DOI: 10.2217/fca.12.58] [Citation(s) in RCA: 227] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Excess generation of reactive oxygen species (ROS) and cytosolic calcium accumulation play major roles in the initiation of programmed cell death during acute myocardial infarction. Cell death may include necrosis, apoptosis and autophagy, and combinations thereof. During ischemia, calcium handling between the sarcoplasmic reticulum and myofilament is disrupted and calcium is diverted to the mitochondria causing swelling. Reperfusion, while essential for survival, reactivates energy transduction and contractility and causes the release of ROS and additional ionic imbalance. During acute ischemia-reperfusion, the principal death pathways are programmed necrosis and apoptosis through the intrinsic pathway, initiated by the opening of the mitochondrial permeability transition pore and outer mitochondrial membrane permeabilization, respectively. Despite intense investigation, the mechanisms of action and modes of regulation of mitochondrial membrane permeabilization are incompletely understood. Extrinsic apoptosis, necroptosis and autophagy may also contribute to ischemia-reperfusion injury. In this review, the roles of dysregulated calcium and ROS and the contributions of Bcl-2 proteins, as well as mitochondrial morphology in promoting mitochondrial membrane permeability change and the ensuing cell death during myocardial infarction are discussed.
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Affiliation(s)
- Keith A Webster
- Department of Molecular & Cellular Pharmacology, University of Miami Medical Center, FL 33101, USA.
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Pollard AE, Barr RC. A new approach for resolution of complex tissue impedance spectra in hearts. IEEE Trans Biomed Eng 2013; 60:2494-503. [PMID: 23625349 DOI: 10.1109/tbme.2013.2258917] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
This study was designed to test the feasibility of using sinusoidal approximation in combination with a new instrumentation approach to resolve complex impedance (uCI) spectra from heart preparations. To assess that feasibility, we applied stimuli in the 10-4000 Hz range and recorded potential differences (uPDs) in a four-electrode configuration that allowed identification of probe constants (Kp) during calibration that were in turn used to measure total tissue resistivity ρt from rabbit ventricular epicardium. Simultaneous acquisition of a signal proportional to the supplied current (Vstim) with uPD allowed identification of the V- I ratio needed for ρt measurement, as well as the phase shift from Vstim to uPD needed for uCI spectra resolution. Performance with components integrated to reduce noise in cardiac electrophysiologic experiments, in particular, and provide accurate electrometer-based measurements, in general, was first characterized in tests using passive loads. Load tests showed accurate uCI recovery with mean uPD SNRs between 10 (1) and 10 (3) measured with supplied currents as low as 10 nA. Comparable performance characteristics were identified during calibration of nine arrays built with 250 μm Ag/AgCl electrodes, with uCIs that matched analytic predictions and no apparent effect of frequency ( F = 0.12, P = 0.99). The potential ability of parasitic capacitance in the presence of the electrode-electrolyte interface associated with the small sensors to influence the uCI spectra was therefore limited by the instrumentation. Resolution of uCI spectra in rabbit ventricle allowed measurement of ρt = 134 ± 53 Ω· cm. The rapid identification available with this strategy provides an opportunity for new interpretations of the uCI spectra to improve quantification of disease-, region-, tissue-, and species-dependent intercellular uncoupling in hearts.
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Sánchez JA, Rodríguez-Sinovas A, Barba I, Miró-Casas E, Fernández-Sanz C, Ruiz-Meana M, Alburquerque-Béjar JJ, García-Dorado D. Activation of RISK and SAFE pathways is not involved in the effects of Cx43 deficiency on tolerance to ischemia-reperfusion injury and preconditioning protection. Basic Res Cardiol 2013; 108:351. [PMID: 23595215 DOI: 10.1007/s00395-013-0351-3] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Revised: 03/22/2013] [Accepted: 04/09/2013] [Indexed: 10/27/2022]
Abstract
Connexin 43 (Cx43) deficiency increases myocardial tolerance to ischemia-reperfusion injury and abolishes preconditioning protection. It is not known whether modifications in baseline signaling through protective RISK or SAFE pathways or in response to preconditioning may contribute to these effects. To answer this question we used Cx43(Cre-ER(T)/fl) mice, in which Cx43 expression is abolished after 4-hydroxytamoxifen (4-OHT) administration. Isolated hearts from Cx43(Cre-ER(T)/fl) mice, or from Cx43(fl/fl) controls, treated with vehicle or 4-OHT, were submitted to global ischemia (40 min) and reperfusion. Cx43 deficiency was associated with reduced infarct size after ischemia-reperfusion (11.17 ± 3.25 % vs. 65.04 ± 3.79, 59.31 ± 5.36 and 65.40 ± 4.91, in Cx43(fl/fl) animals treated with vehicle, Cx43(fl/fl) mice treated with 4-OHT, and Cx43(Cre-ER(T)/fl) mice treated with vehicle, respectively, n = 8-9, p < 0.001). However, the ratio phosphorylated/total protein expression for Akt, ERK-1/2, GSK3β and STAT3 was not increased in normoxic samples from animals lacking Cx43. Instead, a reduction in the phosphorylation state of GSK3β was observed in Cx43-deficient mice (ratio: 0.15 ± 0.02 vs. 0.56 ± 0.11, 0.77 ± 0.15, and 0.46 ± 0.14, respectively, n = 5-6, p < 0.01). Furthermore, ischemic preconditioning (IPC, 4 cycles of 3.5 min of ischemia and 5 min of reperfusion) increased phosphorylation of ERK-1/2, GSK3β, and STAT3 in all hearts without differences between groups (n = 5-6, p < 0.05), although Cx43 deficient mice were not protected by either IPC or pharmacological preconditioning with diazoxide. Our data demonstrate that modification of RISK and SAFE signaling does not contribute to the role of Cx43 in the increased tolerance to myocardial ischemia-reperfusion injury and in preconditioning protection.
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Affiliation(s)
- Jose A Sánchez
- Laboratorio de Cardiología Experimental, Vall d'Hebron University Hospital and Research Institute, Universitat Autònoma de Barcelona, Pg. Vall d'Hebron 119-129, 08035 Barcelona, Spain
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Morel O, Perret T, Delarche N, Labeque JN, Jouve B, Elbaz M, Piot C, Ovize M. Pharmacological approaches to reperfusion therapy. Cardiovasc Res 2012; 94:246-52. [DOI: 10.1093/cvr/cvs114] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
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20
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Sánchez JA, Rodríguez-Sinovas A, Fernández-Sanz C, Ruiz-Meana M, García-Dorado D. Effects of a reduction in the number of gap junction channels or in their conductance on ischemia-reperfusion arrhythmias in isolated mouse hearts. Am J Physiol Heart Circ Physiol 2011; 301:H2442-53. [PMID: 21949115 DOI: 10.1152/ajpheart.00540.2011] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
A transient reduction of cell coupling during reperfusion limits myocardial necrosis, but little is known about its arrhythmogenic effects during ischemia-reperfusion. Thus, we analyzed the effect of an extreme reduction in the number of gap junction channels or in their unitary conductance on ventricular arrhythmias during myocardial ischemia-reperfusion. Available gap junction uncouplers have electrophysiological effects independent from their uncoupling actions. Thus, isolated hearts from Cx43(Cre-ER(T)/fl) mice treated with 4-hydroxytamoxifen (4-OHT), from Cx43KI32 mice [in which connexin (Cx)43 was replaced with Cx32], and from control animals were submitted to regional ischemia and reperfusion, and spontaneous and induced ventricular arrhythmias were monitored. In additional hearts, changes in activation time and electrical impedance during global ischemia-reperfusion were assessed. In contrast to treatment with 4-OHT, replacement of Cx43 with Cx32 did not modify baseline activation time or electrical impedance. However, the number of extrasistole and ventricular tachyarrhythmias was higher in isolated hearts from Cx43KI32 and 4-OHT-treated Cx43(Cre-ER(T)/fl) animals versus wild-type animals during normoxia, ischemia (12.29 ± 3.26 and 52.17 ± 22.51 vs. 3.00 ± 1.46 spontaneous tachyarrhythmias, P < 0.05), and reperfusion. The impairment in conduction during ischemia was steeper in isolated hearts from Cx43KI32 animals, whereas changes in myocardial impedance were attenuated during ischemia in both transgenic models, suggesting altered cell-to-cell coupling at baseline. In conclusion, both reduction of Cx43 with 4-OHT and replacement of Cx43 by less-conductive Cx32 were arrhythmogenic under normoxia and ischemia-reperfusion, despite no major effects on baseline electrical properties. These results suggest that modifications in gap junction communication silent under normal conditions may be arrhythmogenic during ischemia-reperfusion.
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Affiliation(s)
- Jose A Sánchez
- Laboratorio de Cardiología Experimental, Vall d’Hebron University Hospital, Barcelona, Spain
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Rodríguez-Sinovas A, Sánchez JA, Fernandez-Sanz C, Ruiz-Meana M, Garcia-Dorado D. Connexin and pannexin as modulators of myocardial injury. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1818:1962-70. [PMID: 21839721 DOI: 10.1016/j.bbamem.2011.07.041] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2011] [Revised: 07/20/2011] [Accepted: 07/28/2011] [Indexed: 01/02/2023]
Abstract
Multicellular organisms have developed a variety of mechanisms that allow communication between their cells. Whereas some of these systems, as neurotransmission or hormones, make possible communication between remote areas, direct cell-to-cell communication through specific membrane channels keep in contact neighboring cells. Direct communication between the cytoplasm of adjacent cells is achieved in vertebrates by membrane channels formed by connexins. However, in addition to allowing exchange of ions and small metabolites between the cytoplasms of adjacent cells, connexin channels also communicate the cytosol with the extracellular space, thus enabling a completely different communication system, involving activation of extracellular receptors. Recently, the demonstration of connexin at the inner mitochondrial membrane of cardiomyocytes, probably forming hemichannels, has enlarged the list of actions of connexins. Some of these mechanisms are also shared by a different family of proteins, termed pannexins. Importantly, these systems allow not only communication between healthy cells, but also play an important role during different types of injury. The aim of this review is to discuss the role played by both connexin hemichannels and pannexin channels in cell communication and injury. This article is part of a Special Issue entitled: The Communicating junctions, composition, structure and characteristics.
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22
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Inserte J, Ruiz-Meana M, Rodríguez-Sinovas A, Barba I, Garcia-Dorado D. Contribution of delayed intracellular pH recovery to ischemic postconditioning protection. Antioxid Redox Signal 2011; 14:923-39. [PMID: 20578958 DOI: 10.1089/ars.2010.3312] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Ischemic postconditioning (PoCo) has been proven to be a feasible approach to attenuate reperfusion injury and enhance myocardial salvage in patients with acute myocardial infarction, but its mechanisms have not been completely elucidated yet. Recent studies demonstrate that PoCo may delay the recovery of intracellular pH during initial reperfusion, and that its ability to limit infarct size critically depends on this effect. Prolongation of postischemic intracellular acidosis inhibits hypercontracture, mitochondrial permeability transition, calpain-mediated proteolysis, and gap junction-mediated spread of injury during the first minutes of reflow. This role of prolonged acidosis does not exclude the participation of other pathways in PoCo-induced cardioprotection. On the contrary, it may allow these pathways to act by preventing immediate reperfusion-induced cell death. Moreover, the existence of interactions between intracellular acidosis and endogenous protection signaling cannot be excluded and needs to be investigated. The role of prolonged acidosis in PoCo cardioprotection has important implications in the design of optimal PoCo protocols and in the translation of cardioprotective strategies to patients with on-going myocardial infarction receiving coronary reperfusion.
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Affiliation(s)
- Javier Inserte
- Department of Cardiology, Vall d'Hebron University Hospital and Research Institute, Universitat Autònoma de Barcelona, Barcelona, Spain
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23
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Rodríguez-Sinovas A, Sánchez JA, González-Loyola A, Barba I, Morente M, Aguilar R, Agulló E, Miró-Casas E, Esquerda N, Ruiz-Meana M, García-Dorado D. Effects of substitution of Cx43 by Cx32 on myocardial energy metabolism, tolerance to ischaemia and preconditioning protection. J Physiol 2010; 588:1139-51. [PMID: 20156849 PMCID: PMC2853001 DOI: 10.1113/jphysiol.2009.186577] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2009] [Accepted: 02/08/2010] [Indexed: 12/31/2022] Open
Abstract
Connexin 43 (Cx43) plays an important role in cardioprotective signalling by mechanisms at least in part independent of gap junctional communication. To investigate whether this role is related to specific properties of this connexin isoform, we used a knock-in mouse model in which the coding region of Cx43 is replaced by that of Cx32. Homozygous Cx43KI32 mice showed reduced cell-to-cell Lucifer Yellow transfer (P < 0.01), but QRS duration and left ventricular fractional shortening (echocardiography) were similar to those in wild-type animals. NMR spectroscopy detected reduced ATP and increased lactate content in myocardium from homozygous Cx43KI32 animals (P < 0.05). Despite this, isolated homozygous Cx43KI32 hearts showed smaller infarcts after ischaemia-reperfusion (40 min/60 min) as compared to hearts from heterozygous and wild-type animals (13 and 31% reduction, respectively, P < 0.05). Cardiac myocytes isolated from Cx43KI32 mouse hearts also showed a reduced rate of cell death after simulated ischaemia-reperfusion. In a separate series of experiments, both ischaemic (4 cycles of 3.5 min of ischaemia and 5 min of reperfusion) and pharmacological (50 micromol l(-1) diazoxide, 10 min) preconditioning reduced infarct size in hearts from wild-type mice (by 24.84 and 26.63%, respectively, P < 0.05), but only ischaemic preconditioning was effective in hearts from heterozygous animals and both preconditioning strategies failed to protect Cx43KI32 homozygous hearts. These results demonstrate that Cx43 has an important and previously unknown modulatory effect in myocardial energy metabolism and tolerance to ischaemia, and plays a critical role in preconditioning protection, by mechanisms that are specific for this connexin isoform.
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Affiliation(s)
- Antonio Rodríguez-Sinovas
- Laboratorio de Cardiología Experimental, Servicio de Cardiología, Hospital Universitari Vall d'Hebron, Barcelona, Spain
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Contractile properties of esophageal striated muscle: comparison with cardiac and skeletal muscles in rats. J Biomed Biotechnol 2010; 2010:459789. [PMID: 20379364 PMCID: PMC2850148 DOI: 10.1155/2010/459789] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2009] [Accepted: 02/01/2010] [Indexed: 12/02/2022] Open
Abstract
The external muscle layer of the mammalian esophagus consists of striated muscles. We investigated the contractile properties of esophageal striated muscle by comparison with those of skeletal and cardiac muscles. Electrical field stimulation with single pulses evoked twitch-like contractile responses in esophageal muscle, similar to those in skeletal muscle in duration and similar to those in cardiac muscle in amplitude. The contractions of esophageal muscle were not affected by an inhibitor of gap junctions. Contractile responses induced by high potassium or caffeine in esophageal muscle were analogous to those in skeletal muscle. High-frequency stimulation induced a transient summation of contractions followed by sustained contractions with amplitudes similar to those of twitch-like contractions, although a large summation was observed in skeletal muscle. The results demonstrate that esophageal muscle has properties similar but not identical to those of skeletal muscle and that some specific properties may be beneficial for esophageal peristalsis.
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Du Y, Zhang S, Wu H, Zou A, Lei M, Cheng L, Liao Y. Glycyrretinic acid blocks cardiac sodium channels expressed in Xenopus oocytes. JOURNAL OF ETHNOPHARMACOLOGY 2009; 125:318-323. [PMID: 19559778 DOI: 10.1016/j.jep.2009.06.016] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2008] [Revised: 04/23/2009] [Accepted: 06/17/2009] [Indexed: 05/28/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Licorice has been used to treat many ailments including cardiovascular disorders in China for long time. Recent studies have shown that the cardiac actions of licorice have been attributed to its active component, glycyrretinic acid (GA). However, its mechanism remains poorly understood. AIM OF THE STUDY The effects of GA on the cardiac sodium currents (I(Na)), L-type calcium currents (I(Ca,L)) and hyperpolarization-activated inward currents (I(f)) were investigated. MATERIALS AND METHODS Human isoforms of wild-type and DeltaKPQ-mutant type sodium channels were expressed in Xenopus oocytes, and the resulting currents (peak and late I(Na)) were recorded using a two-microelectrode voltage-clamp technique. A perforated patch clamp technique was employed to record I(Ca,L) and I(f) from isolated rabbit sinoatrial node pacemaker cells. RESULTS GA inhibited peak I(Na) (33% at 90 microM) and late I(Na) (72% at 90 microM), but caused no significant effects on I(Ca,L) and I(f). CONCLUSION GA blocked cardiac sodium currents, particularly late I(Na.) Our findings might help to understand the traditional use of licorice in the treatment of cardiovascular disorders, because reduction of sodium currents (particularly late I(Na)) would be expected to provide protection from Na(+)-induced Ca(2+) overload and cell damage.
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Affiliation(s)
- Yimei Du
- Ion Channelopathy Research Center, Institute of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, PR China
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Miro-Casas E, Ruiz-Meana M, Agullo E, Stahlhofen S, Rodríguez-Sinovas A, Cabestrero A, Jorge I, Torre I, Vazquez J, Boengler K, Schulz R, Heusch G, Garcia-Dorado D. Connexin43 in cardiomyocyte mitochondria contributes to mitochondrial potassium uptake. Cardiovasc Res 2009; 83:747-56. [PMID: 19460776 DOI: 10.1093/cvr/cvp157] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
AIMS Connexin43 is present at the inner membrane of cardiomyocyte mitochondria (mCx43), but its function remains unknown. METHODS AND RESULTS In this study we verified the presence of mCx43 by a mass spectrometry-based proteomic approach in purified mitochondrial preparations from mouse myocardium and determined by western blot analysis that the C-terminus of mCx43 is oriented towards the intermembrane space. Cross-linking studies with dimethylsuberimidate indicated the presence of Cx43 hexamers in mitochondrial membranes. The contribution of Cx43 to both mitochondrial dye uptake and K(+) flux was assessed in wild-type mice using hemichannel blockers and Cx43KI32 mice in which Cx43 had been replaced by Cx32. Uptake of the Cx43 hemichannel-permeant dye Lucifer Yellow was reduced in mitochondria from wild-type mice by two hemichannel blockers (carbenoxolone and heptanol) and in Cx43KI32 compared with wild-type mice. Mitochondrial K(+) influx (PBFI fluorescence) was decreased in digitonin-permeabilized cardiomyocytes from Cx32 mutants compared with wild-type mice, and addition of the Cx43 hemichannel blocker 18alpha-glycyrrhetinic acid had an inhibitory effect on mitochondrial K(+) influx in wild-type cardiomyocytes, but not in cardiomyocytes from Cx32 mutants. CONCLUSION These results indicate that mCx43 contributes to mitochondrial K(+) flux in cardiomyocytes, potentially by forming hemichannel-like structures.
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Affiliation(s)
- Elisabet Miro-Casas
- Servicio de Cardiología, Hospital Universitari Vall d'Hebron, Pg. Vall d'Hebron 119, Barcelona 08035, Spain
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Bocian R, Posłuszny A, Kowalczyk T, Gołębiewski H, Konopacki J. The effect of carbenoxolone on hippocampal formation theta rhythm in rats: In vitro and in vivo approaches. Brain Res Bull 2009; 78:290-8. [PMID: 19013505 DOI: 10.1016/j.brainresbull.2008.10.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2008] [Revised: 10/15/2008] [Accepted: 10/16/2008] [Indexed: 10/21/2022]
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Ruiz-Meana M, García-Dorado D. Fisiopatología del daño miocárdico por isquemia-reperfusión: nuevas oportunidades terapéuticas en el infarto agudo de miocardio. Rev Esp Cardiol 2009. [DOI: 10.1016/s0300-8932(09)70162-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Ruiz-Meana M, García-Dorado D. Pathophysiology of Ischemia-Reperfusion Injury: New Therapeutic Options for Acute Myocardial Infarction. ACTA ACUST UNITED AC 2009; 62:199-209. [DOI: 10.1016/s1885-5857(09)71538-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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Liang Q, Sohn K, Punske BB. Propagation and electrical impedance changes due to ischemia, hypoxia and reperfusion in mouse hearts. CONFERENCE PROCEEDINGS : ... ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL CONFERENCE 2008; 2006:1560-3. [PMID: 17946904 DOI: 10.1109/iembs.2006.260296] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The purpose of this study is to quantitatively characterize major electrical markers of cardiac ischemia in normal mouse hearts to establish a set of baseline parameters for evaluation of genetically altered mouse hearts. Optical and electrical imaging techniques were coupled with impedance measurements to quantify changes induced by global ischemia. Optical and electrical mapping studies revealed the time course of conduction slowing and local inactivation during 30 minutes of ischemia or hypoxia. Measures of myocardial electrical impedance (MEI) were made during 30 and 120 minutes of global ischemia and proved to be qualitatively similar yet quantitatively distinct when compared to results reported from other mammals. The results of this study can now be applied in the analysis of genetically altered mouse hearts that are currently becoming available to help us understand cardiac death in disease.
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Affiliation(s)
- Qiansheng Liang
- Department of Bioengineering, University of Utah, Salt Lake City, UT 84112-5000, USA.
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Rodríguez-Sinovas A, Abdallah Y, Piper HM, Garcia-Dorado D. Reperfusion injury as a therapeutic challenge in patients with acute myocardial infarction. Heart Fail Rev 2007; 12:207-16. [PMID: 17530396 DOI: 10.1007/s10741-007-9039-9] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Cardiomyocyte death secondary to transient ischemia occurs mainly during the first minutes of reperfusion, in the form of contraction band necrosis involving sarcolemmal rupture. Cardiomyocyte hypercontracture caused by re-energisation and pH recovery in the presence of impaired cytosolic Ca(2+) control as well as calpain-mediated cytoskeletal fragility play prominent roles in this type of cell death. Hypercontracture can propagate to adjacent cells through gap junctions. More recently, opening of the mitochondrial permeability transition pore has been shown to participate in reperfusion-induced necrosis, although its precise relation with hypercontracture has not been established. Experimental studies have convincingly demonstrated that infarct size can be markedly reduced by therapeutic interventions applied at the time of reperfusion, including contractile blockers, inhibitors of Na(+)/Ca(2+) exchange, gap junction blockers, or particulate guanylyl cyclase agonists. However, in most cases drugs for use in humans have not been developed and tested for these targets, while the effect of existing drugs with potential cardioprotective effect is not well established or understood. Research effort should be addressed to elucidate the unsolved issues of the molecular mechanisms of reperfusion-induced cell death, to identify and validate new targets and to develop appropriate drugs. The potential benefits of limiting infarct size in patients with acute myocardial infarction receiving reperfusion therapy are enormous.
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Affiliation(s)
- Antonio Rodríguez-Sinovas
- Laboratorio de Cardiología Experimental, Servicio de Cardiología, Hospital Universitario Vall d'Hebron, Passeig Vall d'Hebron 119, Barcelona 08035, Spain
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Nygren A, Olson ML, Chen KY, Emmett T, Kargacin G, Shimoni Y. Propagation of the cardiac impulse in the diabetic rat heart: reduced conduction reserve. J Physiol 2007; 580:543-60. [PMID: 17185336 PMCID: PMC2075555 DOI: 10.1113/jphysiol.2006.123729] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2006] [Accepted: 12/18/2006] [Indexed: 01/22/2023] Open
Abstract
Diabetes mellitus is a growing epidemic with severe cardiovascular complications. Although much is known about mechanical and electrical cardiac dysfunction in diabetes, few studies have investigated propagation of the electrical signal in the diabetic heart and the associated changes in intercellular gap junctions. This study was designed to investigate these issues, using hearts from control and diabetic rats. Diabetic conditions were induced by streptozotocin (STZ), given i.v. 7-14 days before experiments. Optical mapping with the voltage-sensitive dye di-4-ANEPPS, using hearts perfused on a Langendorff apparatus, showed little change in baseline conduction velocity in diabetic hearts, reflecting the large reserve of function. However, both the gap junction uncoupler heptanol (0.5-1 mM) and elevated potassium (9 mM, to reduce cell excitability) produced a significantly greater slowing of impulse propagation in diabetic hearts than in controls. The maximal action potential upstroke velocity (an index of the sodium current) and resting potential was similar in single ventricular myocytes from control and diabetic rats, suggesting similar electrical excitability. Immunoblotting of connexin 43 (Cx43), a major gap junction component, showed no change in total expression. However, immunofluorescence labelling of Cx43 showed a significant redistribution, apparent as enhanced Cx43 lateralization. This was quantified and found to be significantly larger than in control myocytes. Labelling of two other gap junction proteins, N-cadherin and beta-catenin, showed a (partial) loss of co-localization with Cx43, indicating that enhancement of lateralized Cx43 is associated with non-functional gap junctions. In conclusion, conduction reserve is smaller in the diabetic heart, priming it for impaired conduction upon further challenges. This can desynchronize contraction and contribute to arrhythmogenesis.
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Affiliation(s)
- A Nygren
- Department of Electrical and Computer Engineering, University of Calgary, Alberta, Canada
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Rodríguez-Sinovas A, Cabestrero A, López D, Torre I, Morente M, Abellán A, Miró E, Ruiz-Meana M, García-Dorado D. The modulatory effects of connexin 43 on cell death/survival beyond cell coupling. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2007; 94:219-32. [PMID: 17462722 DOI: 10.1016/j.pbiomolbio.2007.03.003] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Connexins form a diverse and ubiquitous family of integral membrane proteins. Characteristically, connexins are assembled into intercellular channels that aggregate into discrete cell-cell contact areas termed gap junctions (GJ), allowing intercellular chemical communication, and are essential for propagation of electrical impulses in excitable tissues, including, prominently, myocardium, where connexin 43 (Cx43) is the most important isoform. Previous studies have shown that GJ-mediated communication has an important role in the cellular response to stress or ischemia. However, recent evidence suggests that connexins, and in particular Cx43, may have additional effects that may be important in cell death and survival by mechanisms independent of cell to cell communication. Connexin hemichannels, located at the plasma membrane, may be important in paracrine signaling that could influence intracellular calcium and cell survival by releasing intracellular mediators as ATP, NAD(+), or glutamate. In addition, recent studies have shown the presence of connexins in cell structures other than the plasma membrane, including the cell nucleus, where it has been suggested that Cx43 influences cell growth and differentiation. In addition, translocation of Cx43 to mitochondria appears to be important for certain forms of cardioprotection. These findings open a new field of research of previously unsuspected roles of Cx43 intracellular signaling.
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Affiliation(s)
- Antonio Rodríguez-Sinovas
- Laboratorio de Cardiología Experimental, Servicio de Cardiologia, Hospital Vall d'Hebron, Barcelona, Spain
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Boengler K, Konietzka I, Buechert A, Heinen Y, Garcia-Dorado D, Heusch G, Schulz R. Loss of ischemic preconditioning's cardioprotection in aged mouse hearts is associated with reduced gap junctional and mitochondrial levels of connexin 43. Am J Physiol Heart Circ Physiol 2006; 292:H1764-9. [PMID: 17142336 DOI: 10.1152/ajpheart.01071.2006] [Citation(s) in RCA: 141] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Connexin 43 (Cx43) is localized at left ventricular (LV) gap junctions and in cardiomyocyte mitochondria. A genetically induced reduction of Cx43 as well as blockade of mitochondrial Cx43 import abolishes the infarct size (IS) reduction by ischemic preconditioning (IP). With progressing age, Cx43 content in ventricular and atrial tissue homogenates is reduced. We now investigated whether or not 1) the mitochondrial Cx43 content is reduced in aged mice hearts and 2) IS reduction by IP is lost in aged mice hearts in vivo. Confirming previous results, sarcolemmal Cx43 content was reduced in aged (>13 mo) compared with young (<3 mo) C57Bl/6 mice hearts, whereas the expression levels of protein kinase C epsilon and endothelial nitric oxide synthase remained unchanged. Also in mitochondria isolated from aged mice LV myocardium, Western blot analysis indicated a 40% decrease in Cx43 content compared with mitochondria isolated from young mice hearts. In young mice hearts, IP by one cycle of 10 min ischemia and 10 min reperfusion reduced IS (% of area at risk) following 30 min regional ischemia and 120 min reperfusion from 67.7 +/- 3.3 (n = 17) to 34.2 +/- 6.6 (n = 5, P < 0.05). In contrast, IP's cardioprotection was lost in aged mice hearts, since IS in nonpreconditioned (57.5 +/- 4.0, n = 10) and preconditioned hearts (65.4 +/- 6.3, n = 8, P = not significant) was not different. In conclusion, mitochondrial Cx43 content is decreased in aged mouse hearts. The reduced levels of Cx43 may contribute to the age-related loss of cardioprotection by IP.
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Affiliation(s)
- Kerstin Boengler
- Institut für Pathophysiologie, Universitätsklinikum Essen, Germany
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Gołebiewski H, Eckersdorf B, Konopacki J. Electrical coupling underlies theta rhythm in freely moving cats. Eur J Neurosci 2006; 24:1759-70. [PMID: 16965552 DOI: 10.1111/j.1460-9568.2006.04993.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The role of gap junction coupling in the generation of theta rhythms in freely moving cats was investigated in a present study. Two gap junction blockers, carbenoxolone and quinine, were administered intraperitoneally and intrahippocampally; both gap junction blockers abolished or diminished (respectively) hippocampal formation theta. The inhibitory effect developed approximately 30 min after drug administration. This effect was found to be reversible. Our results provide the first direct in vivo evidence for the contribution of gap junction communication in mechanisms of neural synchrony, underlying the production of theta in in vivo conditions.
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Affiliation(s)
- Henryk Gołebiewski
- Department of Neurobiology, The University of Łódź, Łódź, 90-222, Rewolucji 1905 no. 66, Poland
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Srisakuldee W, Nickel BE, Fandrich RR, Jiang ZS, Kardami E. Administration of FGF-2 to the heart stimulates connexin-43 phosphorylation at protein kinase C target sites. ACTA ACUST UNITED AC 2006; 13:13-9. [PMID: 16613776 DOI: 10.1080/15419060600631326] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Fibroblast growth factor-2 (FGF-2) confers acute, preconditioning-like cardiac resistance to ischemic injury in a protein kinase C (PKC)-dependent fashion. One of the downstream targets of PKC is the gap junction protein connexin-43 (Cx43). We thus examined the effects of FGF-2 on Cx43 phosphorylation at specific PKC sites in the adult heart. Rat hearts perfused ex vivo for 20 min with an FGF-2-containing solution displayed increased levels of phosphorylated 44-45 kDa Cx43, assessed by western blotting. In addition, FGF-2 significantly upregulated phosphorylation of the PKC target serines 262 and 368 on Cx43 at intercalated disks, assessed using phosphospecific antibodies in immunolocalization and western blotting assays. Our data show that FGF-2, administered by perfusion, can alter the phosphorylation status of Cx43 at cardiomyocyte intercalated disks, and suggest a link between phosphorylation of Cx43 at specific PKC sites and FGF-2 cardioprotection.
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Affiliation(s)
- Wattamon Srisakuldee
- Department of Human Anatomy and Cell Sciences, Institute of Cardiovascular Sciences, St. Boniface Research Centre, University of Manitoba, Winnipeg, Manitoba, Canada
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Kresh JY. Cell replacement therapy: The functional importance of myocardial architecture and intercellular gap-junction distribution. J Thorac Cardiovasc Surg 2006; 131:1310-3. [PMID: 16733163 DOI: 10.1016/j.jtcvs.2006.02.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2006] [Revised: 02/22/2006] [Accepted: 02/24/2006] [Indexed: 01/14/2023]
Affiliation(s)
- J Yasha Kresh
- Department of Cardiothoracic Surgery and Medicine, Drexel University College of Medicine, Philadelphia, Pa 19102, USA.
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Rodriguez-Sinovas A, Boengler K, Cabestrero A, Gres P, Morente M, Ruiz-Meana M, Konietzka I, Miró E, Totzeck A, Heusch G, Schulz R, Garcia-Dorado D. Translocation of connexin 43 to the inner mitochondrial membrane of cardiomyocytes through the heat shock protein 90-dependent TOM pathway and its importance for cardioprotection. Circ Res 2006; 99:93-101. [PMID: 16741159 DOI: 10.1161/01.res.0000230315.56904.de] [Citation(s) in RCA: 195] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
We have previously shown that connexin 43 (Cx43) is present in mitochondria, that its genetic depletion abolishes the protection of ischemia- and diazoxide-induced preconditioning, and that it is involved in reactive oxygen species (ROS) formation in response to diazoxide. Here we investigated the intramitochondrial localization of Cx43, the mechanism of Cx43 translocation to mitochondria and the effect of inhibiting translocation on the protection of preconditioning. Confocal microscopy of mitochondria devoid of the outer membrane and Western blotting on fractionated mitochondria showed that Cx43 is located at the inner mitochondrial membrane, and coimmunoprecipitation of Cx43 with Tom20 (Translocase of the outer membrane 20) and with heat shock protein 90 (Hsp90) indicated that it interacts with the regular mitochondrial protein import machinery. In isolated rat hearts, geldanamycin, a blocker of Hsp90-dependent translocation of proteins to the inner mitochondrial membrane through the TOM pathway, rapidly (15 minutes) reduced mitochondrial Cx43 content by approximately one-third in the absence or presence of diazoxide. Geldanamycin alone had no effect on infarct size, but it ablated the protection against infarction afforded by diazoxide. Geldanamycin abolished the 2-fold increase in mitochondrial Cx43 induced by 2 preconditioning cycles of ischemia/reperfusion, but this effect was not associated with reduced protection. These results demonstrate that Cx43 is transported to the inner mitochondrial membrane through translocation via the TOM complex and that a normal mitochondrial Cx43 content is important for the diazoxide-related pathway of preconditioning.
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Rodríguez-Sinovas A, García-Dorado D, Ruiz-Meana M, Soler-Soler J. Protective effect of gap junction uncouplers given during hypoxia against reoxygenation injury in isolated rat hearts. Am J Physiol Heart Circ Physiol 2006; 290:H648-56. [PMID: 16183732 DOI: 10.1152/ajpheart.00439.2005] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
It has been shown that cell-to-cell chemical coupling may persist during severe myocardial hypoxia or ischemia. We aimed to analyze the effects of different, chemically unrelated gap junction uncouplers on the progression of ischemic injury in hypoxic myocardium. First, we analyzed the effects of heptanol, 18α-glycyrrhetinic acid, and palmitoleic acid on intracellular Ca2+ concentration during simulated hypoxia (2 mM NaCN) in isolated cardiomyocytes. Next, we analyzed their effects on developed and diastolic tension and electrical impedance in 47 isolated rat hearts submitted to 40 min of hypoxia and reoxygenation. All treatments were applied only during the hypoxic period. Cell injury was determined by lactate dehydrogenase (LDH) release. Heptanol, but not 18α-glycyrrhetinic acid nor palmitoleic acid, attenuated the increase in cytosolic Ca2+ concentration induced by simulated ischemia in cardiomyocytes and delayed rigor development (rigor onset at 7.31 ± 0.71 min in controls vs. 14.76 ± 1.44 in heptanol-treated hearts, P < 0.001) and the onset of the marked changes in electrical impedance (tissue resistivity: 4.02 ± 0.29 vs. 7.75 ± 1.84 min, P = 0.016) in hypoxic rat hearts. LDH release from hypoxic hearts was minimal and was not significantly modified by drugs. However, all gap junction uncouplers, given during hypoxia, attenuated LDH release during subsequent reoxygenation. Dose-response analysis showed that increasing heptanol concentration beyond the level associated with maximal effects on cell coupling resulted in further protection against hypoxic injury. In conclusion, gap junction uncoupling during hypoxia has a protective effect on cell death occurring upon subsequent reoxygenation, and heptanol has, in addition, a marked protective effect independent of its uncoupling actions.
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Affiliation(s)
- Antonio Rodríguez-Sinovas
- Laboratorio de Investigación Cardiovascular, Hospitals Vall d'Hebron, Pg. Vall d'Hebron 119-129, 08035 Barcelona, Spain
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