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Falck AT, Lund BA, Johansen D, Lund T, Ytrehus K. The Ambivalence of Connexin43 Gap Peptides in Cardioprotection of the Isolated Heart against Ischemic Injury. Int J Mol Sci 2022; 23:ijms231710197. [PMID: 36077595 PMCID: PMC9456187 DOI: 10.3390/ijms231710197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 08/25/2022] [Accepted: 08/31/2022] [Indexed: 11/16/2022] Open
Abstract
The present study investigates infarct-reducing effects of blocking ischemia-induced opening of connexin43 hemichannels using peptides Gap19, Gap26 or Gap27. Cardioprotection by ischemic preconditioning (IPC) and Gap peptides was compared, and combined treatment was tested in isolated, perfused male rat hearts using function and infarct size after global ischemia, high-resolution respirometry of isolated mitochondrial and peptide binding kinetics as endpoints. The Gap peptides reduced infarct size significantly when given prior to ischemia plus at reperfusion (Gap19 76.2 ± 2.7, Gap26 72.9 ± 5.8 and Gap27 71.9 ± 5.8% of untreated control infarcts, mean ± SEM). Cardioprotection was lost when Gap26, but not Gap27 or Gap19, was combined with triggering IPC (IPC 73.4 ± 5.5, Gap19-IPC 60.9 ± 5.1, Gap26-IPC 109.6 ± 7.8, Gap27-IPC 56.3 ± 8.0% of untreated control infarct). Binding stability of peptide Gap26 to its specific extracellular loop sequence (EL2) of connexin43 was stronger than Gap27 to its corresponding loop EL1 (dissociation rate constant Kd 0.061 ± 0.004 vs. 0.0043 ± 0.0001 s-1, mean ± SD). Mitochondria from IPC hearts showed slightly but significantly reduced respiratory control ratio (RCR). In vitro addition of Gap peptides did not significantly alter respiration. If transient hemichannel activity is part of the IPC triggering event, inhibition of IPC triggering stimuli might limit the use of cardioprotective Gap peptides.
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Affiliation(s)
- Aleksander Tank Falck
- Cardiovascular Research Group, Department of Medical Biology, UiT The Arctic University of Norway, 9037 Tromsø, Norway
| | - Bjarte Aarmo Lund
- Hylleraas Centre for Quantum Molecular Sciences, Department of Chemistry, Faculty of Science and Technology, UiT The Arctic University of Norway, 9037 Tromsø, Norway
| | - David Johansen
- Department of Internal Medicine, University Hospital of North Norway, 9019 Tromsø, Norway
| | - Trine Lund
- Cardiovascular Research Group, Department of Medical Biology, UiT The Arctic University of Norway, 9037 Tromsø, Norway
| | - Kirsti Ytrehus
- Cardiovascular Research Group, Department of Medical Biology, UiT The Arctic University of Norway, 9037 Tromsø, Norway
- Correspondence:
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Martins-Marques T, Rodriguez-Sinovas A, Girao H. Cellular crosstalk in cardioprotection: Where and when do reactive oxygen species play a role? Free Radic Biol Med 2021; 169:397-409. [PMID: 33892116 DOI: 10.1016/j.freeradbiomed.2021.03.044] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Revised: 03/14/2021] [Accepted: 03/25/2021] [Indexed: 12/16/2022]
Abstract
A well-balanced intercellular communication between the different cells within the heart is vital for the maintenance of cardiac homeostasis and function. Despite remarkable advances on disease management and treatment, acute myocardial infarction remains the major cause of morbidity and mortality worldwide. Gold standard reperfusion strategies, namely primary percutaneous coronary intervention, are crucial to preserve heart function. However, reestablishment of blood flow and oxygen levels to the infarcted area are also associated with an accumulation of reactive oxygen species (ROS), leading to oxidative damage and cardiomyocyte death, a phenomenon termed myocardial reperfusion injury. In addition, ROS signaling has been demonstrated to regulate multiple biological pathways, including cell differentiation and intercellular communication. Given the importance of cell-cell crosstalk in the coordinated response after cell injury, in this review, we will discuss the impact of ROS in the different forms of inter- and intracellular communication, as well as the role of gap junctions, tunneling nanotubes and extracellular vesicles in the propagation of oxidative damage in cardiac diseases, particularly in the context of ischemia/reperfusion injury.
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Affiliation(s)
- Tania Martins-Marques
- Univ Coimbra, Coimbra Institute for Clinical and Biomedical Research (iCBR), Faculty of Medicine, Coimbra, Portugal; Univ Coimbra, Center for Innovative Biomedicine and Biotechnology (CIBB), Coimbra, Portugal; Clinical Academic Centre of Coimbra (CACC), Coimbra, Portugal
| | - Antonio Rodriguez-Sinovas
- Cardiovascular Diseases Research Group, Department of Cardiology, Vall D'Hebron Institut de Recerca (VHIR), Vall D'Hebron Hospital Universitari, Vall D'Hebron Barcelona Hospital Campus, Passeig Vall D'Hebron, 119-129, 08035, Barcelona, Spain; Departament de Medicina, Universitat Autònoma de Barcelona, 08193, Bellaterra, Spain; Centro de Investigación Biomédica en Red Sobre Enfermedades Cardiovasculares (CIBERCV), Madrid, Spain
| | - Henrique Girao
- Univ Coimbra, Coimbra Institute for Clinical and Biomedical Research (iCBR), Faculty of Medicine, Coimbra, Portugal; Univ Coimbra, Center for Innovative Biomedicine and Biotechnology (CIBB), Coimbra, Portugal; Clinical Academic Centre of Coimbra (CACC), Coimbra, Portugal.
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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: 53] [Impact Index Per Article: 17.7] [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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Boardman NT, Falck AT, Lund T, Chu X, Martin-Armas M, Norvik JV, Jenssen TG, Ytrehus K. Human concentrations of uric acid scavenges adaptive and maladaptive reactive oxygen species in isolated rat hearts subjected to ischemic stress. Can J Physiol Pharmacol 2019; 98:139-146. [PMID: 31518503 DOI: 10.1139/cjpp-2019-0024] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Uric acid is a purine degradation product but also an important antioxidant and reactive oxygen species (ROS) scavenger. Experimental settings that mimic myocardial ischemia-reperfusion have not included uric acid despite that it is always present in human extracellular fluid and plasma. We hypothesized that uric acid has an important role in myocardial ROS scavenging. Here, we tested the cardiac response to uric acid on infarct size following ischemia-reperfusion with and without exacerbated oxidative stress due to acute pressure overload and during preconditioning. We also examined mitochondrial respiration and ROS-induced mitochondrial permeability transition pore opening. Under exacerbated ROS stress induced by high-pressure perfusion, uric acid lowered oxidative stress and reduced infarct size. In contrast, uric acid blocked cardioprotection induced by ischemic preconditioning. However, this effect was reversed by probenecid, an inhibitor of cellular uptake of uric acid. In accordance, in intact cardiomyocytes, extracellular uric acid reduced the susceptibility of mitochondria towards opening of the permeability transition pore, suggesting that uric acid may prevent ischemia-reperfusion injury due to scavenging of maladaptive ROS. Moreover, as uric acid also scavenges adaptive ROS, this may interfere with preconditioning. Altogether, uric acid might be a confounder when translating preclinical experimental results into clinical treatment.
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Affiliation(s)
- Neoma T Boardman
- Cardiovascular Research Group, Department of Medical Biology, UiT-Arctic University of Norway, Tromsø, Norway
| | - Aleksander Tank Falck
- Cardiovascular Research Group, Department of Medical Biology, UiT-Arctic University of Norway, Tromsø, Norway
| | - Trine Lund
- Cardiovascular Research Group, Department of Medical Biology, UiT-Arctic University of Norway, Tromsø, Norway
| | - Xi Chu
- Cardiovascular Research Group, Department of Medical Biology, UiT-Arctic University of Norway, Tromsø, Norway
| | - Montserrat Martin-Armas
- Cardiovascular Research Group, Department of Medical Biology, UiT-Arctic University of Norway, Tromsø, Norway
| | - Jon V Norvik
- Cardiovascular Research Group, Department of Medical Biology, UiT-Arctic University of Norway, Tromsø, Norway.,Metabolic and Renal Research Group, Department of Clinical Medicine, UiT-Arctic University of Norway, Tromsø, Norway
| | - Trond G Jenssen
- Metabolic and Renal Research Group, Department of Clinical Medicine, UiT-Arctic University of Norway, Tromsø, Norway.,Department of Organ Transplantation, Section of Nephrology, Oslo University Hospital, Oslo, Norway
| | - Kirsti Ytrehus
- Cardiovascular Research Group, Department of Medical Biology, UiT-Arctic University of Norway, Tromsø, Norway
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Involvement of sphingosine-1-phosphate receptors 2/3 in IR-induced sudden cardiac death. Heart Vessels 2019; 34:1052-1063. [DOI: 10.1007/s00380-018-01323-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Accepted: 12/21/2018] [Indexed: 12/22/2022]
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Extracellular mtDNA activates NF-κB via toll-like receptor 9 and induces cell death in cardiomyocytes. Basic Res Cardiol 2016; 111:42. [PMID: 27164906 DOI: 10.1007/s00395-016-0553-6] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Accepted: 04/05/2016] [Indexed: 12/31/2022]
Abstract
Acute myocardial infarction (AMI) causes sterile inflammation, which exacerbates tissue injury. Elevated levels of circulating mitochondrial DNA (mtDNA) have been associated with AMI. We hypothesized that mtDNA triggers an innate immune response via TLR9 and NF-κB activation, causing cardiomyocyte injury. Murine cardiomyocytes express TLR9 mRNA and protein and were able to internalize fluorescently labeled mouse mtDNA. Incubation of human embryonic kidney cells with serum from AMI patients containing naturally elevated levels of mtDNA induced TLR9-dependent NF-κB activity. This effect was mimicked by isolated mtDNA. mtDNA activated NF-κB in reporter mice both in vivo and in isolated cardiomyocytes. Moreover, incubation of isolated cardiomyocytes with mtDNA induced cell death after 4 and 24 h. Laser confocal microscopy showed that incubation of cardiomyocytes with mtDNA accelerated mitochondrial depolarization induced by reactive oxygen species. In contrast to mtDNA, isolated total DNA did not activate NF-κB nor induce cell death. In conclusion, mtDNA can induce TLR9-dependent NF-κB activation in reporter cells and activate NF-κB in cardiomyocytes. In cardiomyocytes, mtDNA causes mitochondrial dysfunction and death. Endogenous mtDNA in the extracellular space is a danger signal with direct detrimental effects on cardiomyocytes.
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Stenberg TA, Kildal AB, Sanden E, How OJ, Hagve M, Ytrehus K, Larsen TS, Myrmel T. The acute phase of experimental cardiogenic shock is counteracted by microcirculatory and mitochondrial adaptations. PLoS One 2014; 9:e105213. [PMID: 25188581 PMCID: PMC4154851 DOI: 10.1371/journal.pone.0105213] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Accepted: 07/19/2014] [Indexed: 11/24/2022] Open
Abstract
The mechanisms contributing to multiorgan dysfunction during cardiogenic shock are poorly understood. Our goal was to characterize the microcirculatory and mitochondrial responses following ≥10 hours of severe left ventricular failure and cardiogenic shock. We employed a closed-chest porcine model of cardiogenic shock induced by left coronary microembolization (n = 12) and a time-matched control group (n = 6). Hemodynamics and metabolism were measured hourly by intravascular pressure catheters, thermodilution, arterial and organ specific blood gases. Echocardiography and assessment of the sublingual microcirculation by sidestream darkfield imaging were performed at baseline, 2±1 and 13±3 (mean±SD) hours after coronary microembolization. Upon hemodynamic decompensation, cardiac, renal and hepatic mitochondria were isolated and evaluated by high-resolution respirometry. Low cardiac output, hypotension, oliguria and severe reductions in mixed-venous and hepatic O2 saturations were evident in cardiogenic shock. The sublingual total and perfused vessel densities were fully preserved throughout the experiments. Cardiac mitochondrial respiration was unaltered, whereas state 2, 3 and 4 respiration of renal and hepatic mitochondria were increased in cardiogenic shock. Mitochondrial viability (RCR; state 3/state 4) and efficiency (ADP/O ratio) were unaffected. Our study demonstrates that the microcirculation is preserved in a porcine model of untreated cardiogenic shock despite vital organ hypoperfusion. Renal and hepatic mitochondrial respiration is upregulated, possibly through demand-related adaptations, and the endogenous shock response is thus compensatory and protective, even after several hours of global hypoperfusion.
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Affiliation(s)
- Thor Allan Stenberg
- Cardiovascular Research Group, Department of Clinical Medicine, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway
- Department of Cardiothoracic and Vascular Surgery, University Hospital of North Norway, Tromsø, Norway
| | - Anders Benjamin Kildal
- Cardiovascular Research Group, Department of Medical Biology, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway
- Department of Cardiothoracic and Vascular Surgery, University Hospital of North Norway, Tromsø, Norway
| | - Espen Sanden
- Cardiovascular Research Group, Department of Clinical Medicine, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway
- * E-mail: (TM); (ES)
| | - Ole-Jakob How
- Cardiovascular Research Group, Department of Medical Biology, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway
| | - Martin Hagve
- Cardiovascular Research Group, Department of Medical Biology, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway
| | - Kirsti Ytrehus
- Cardiovascular Research Group, Department of Medical Biology, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway
| | - Terje S. Larsen
- Cardiovascular Research Group, Department of Medical Biology, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway
| | - Truls Myrmel
- Cardiovascular Research Group, Department of Clinical Medicine, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway
- Department of Cardiothoracic and Vascular Surgery, University Hospital of North Norway, Tromsø, Norway
- * E-mail: (TM); (ES)
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Bondke Persson A, Persson PB. Tools of our trade. Acta Physiol (Oxf) 2013; 208:289-91. [PMID: 23746114 DOI: 10.1111/apha.12127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Lipoxin a4 preconditioning and postconditioning protect myocardial ischemia/reperfusion injury in rats. Mediators Inflamm 2013; 2013:231351. [PMID: 23956501 PMCID: PMC3730367 DOI: 10.1155/2013/231351] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Revised: 06/15/2013] [Accepted: 06/16/2013] [Indexed: 12/23/2022] Open
Abstract
This study aims to investigate the pre- and postconditioning effects of lipoxin A4 (LXA4) on myocardial damage caused by ischemia/reperfusion (I/R) injury. Seventy-two rats were divided into 6 groups: sham groups (C1 and C2), I/R groups (I/R1 and I/R2), and I/R plus LXA4 preconditioning and postconditioning groups (LX1 and LX2). The serum levels of IL-1β, IL-6, IL-8, IL-10, TNF-α, and cardiac troponin I (cTnI) were measured. The content and the activity of Na+-K+-ATPase as well as the superoxide dismutase (SOD), and malondialdehyde (MDA) levels were determined. Along with the examination of myocardium ultrastructure and ventricular arrhythmia scores (VAS), connexin 43 (Cx43) expression were also detected. Lower levels of IL-1β, IL-6, IL-8, TNF-α, cTnI, MDA content, and VAS and higher levels of IL-10, SOD activity, Na+-K+-ATPase content and activity, and Cx43 expression appeared in LX groups than I/R groups. Besides, H&E staining, TEM examination as well as analysis of gene, and protein confirmed that LXA4 preconditioning was more effective than postconditioning in preventing arrhythmogenesis via the upregulation of Cx43. That is, LXA4 postconditioning had better protective effect on Na+-K+-ATPase and myocardial ultrastructure.
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Duelsner A, Bondke Persson A. Animal models in cardiovascular research. Acta Physiol (Oxf) 2013; 208:1-5. [PMID: 23374112 DOI: 10.1111/apha.12074] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- A. Duelsner
- Center for Cardiovascular Research (CCR); Richard-Thoma-Laboratories for Arteriogenesis Charité-Universitaetsmedizin Berlin; Berlin; Germany
| | - A. Bondke Persson
- Institute of Vegetative Physiology; Charité-Universitaetsmedizin Berlin; Berlin; Germany
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Ragone MI, Torres NS, Consolini AE. Energetic study of cardioplegic hearts under ischaemia/reperfusion and [Ca(2+)] changes in cardiomyocytes of guinea-pig: mitochondrial role. Acta Physiol (Oxf) 2013; 207:369-84. [PMID: 23171431 DOI: 10.1111/apha.12027] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Revised: 09/08/2012] [Accepted: 10/02/2012] [Indexed: 12/25/2022]
Abstract
AIM To study the role of mitochondria in the recovery of guinea-pig hearts exposed to high-K(+)-cardioplegia (CPG) and ischaemia/reperfusion (I/R) METHODS: We measured contractility and heat release in perfused guinea-pig hearts and cytosolic and mitochondrial Ca(2+) by epifluorescence and confocal microscopy in isolated cardiomyocytes loaded with Fluo-4 or Rhod-2. RESULTS In hearts, CPG increased the postischaemic contractile recovery, and this was potentiated by the mNCX blocker clonazepam and the mKATP opener diazoxide, which also prevented the fall in muscle economy. Moreover, CPG prevented the stunning induced by ouabain, which was reduced by clonazepam. In cardiomyocytes, CPG increased fluorescent signals of cytosolic and mitochondrial Ca(2+), while the addition of a mNCX blocker (CGP37157) increased cytosolic but reduced mitochondrial [Ca(2+)]. Ouabain in CPG increased cytosolic Ca(2+) and resting heat, but the addition of CGP37157 reduced them, as well as mitochondrial Ca(2+). CONCLUSIONS CPG, diazoxide and clonazepam improve postischaemic recovery, respectively, by increasing the Ca(2+) cycling and by reducing the mitochondrial Ca(2+) uptake either by uniporter or by mNCX. The mitochondria compete with the leaky sarcoplasmic reticulum (SR) as sink of Ca(2+) in guinea-pig hearts, affecting the postischaemic contractility. CPG also prevented the ouabain-induced dysfunction by avoiding the Ca(2+) overload. Ouabain reduced the synergism between CPG and clonazepam suggesting that [Na(+)]i and SR load influence the mNCX role.
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Affiliation(s)
- M. I. Ragone
- Cátedra de Farmacología, Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas; Universidad Nacional de La Plata (UNLP); La Plata; Argentina
| | - N. S. Torres
- The Nora Eccles Harrison Cardiovascular Research and Training Institute (CVRTI); Salt Lake City; UT; USA
| | - A. E. Consolini
- Cátedra de Farmacología, Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas; Universidad Nacional de La Plata (UNLP); La Plata; Argentina
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Persson AB, Persson PB. Ischaemia, reperfusion, pre-and post-conditioning: telling friend from foe. Acta Physiol (Oxf) 2012; 206:157-9. [PMID: 23017102 DOI: 10.1111/j.1748-1716.2012.02477.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- A. Bondke Persson
- Institute of Vegetative Physiology; Charité-Universitaetsmedizin Berlin; Berlin; Germany
| | - P. B. Persson
- Institute of Vegetative Physiology; Charité-Universitaetsmedizin Berlin; Berlin; Germany
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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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Johansen D, Cruciani V, Sundset R, Ytrehus K, Mikalsen SO. Ischemia Induces Closure of Gap Junctional Channels and Opening of Hemichannels in Heart-derived Cells and Tissue. Cell Physiol Biochem 2011; 28:103-14. [DOI: 10.1159/000331719] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/25/2011] [Indexed: 12/20/2022] Open
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