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Rienmuller T, Shrestha N, Polz M, Stoppacher S, Ziesel D, Migliaccio L, Pelzmann B, Lang P, Zorn-Pauly K, Langthaler S, Opancar A, Baumgartner C, Ucal M, Schindl R, Derek V, Scheruebel S. Shedding Light on Cardiac Excitation: In Vitro and In Silico Analysis of Native Ca 2+ Channel Activation in Guinea Pig Cardiomyocytes using Organic Photovoltaic Devices. IEEE Trans Biomed Eng 2024; PP:1-12. [PMID: 38498749 DOI: 10.1109/tbme.2024.3358240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/20/2024]
Abstract
OBJECTIVE This study aims to explore the potential of organic electrolytic photocapacitors (OEPCs), an innovative photovoltaic device, in mediating the activation of native voltage-gated Cav1.2 channels (ICa,L) in Guinea pig ventricular cardiomyocytes. METHODS Whole-cell patch-clamp recordings were employed to examine light-triggered OEPC mediated ICa,L activation, integrating the channel's kinetic properties into a multicompartment cell model to take intracellular ion concentrations into account. A multidomain model was additionally incorporated to evaluate effects of OEPC-mediated stimulation. The final model combines external stimulation, multicompartmental cell simulation, and a patch-clamp amplifier equivalent circuit to assess the impact on achievable intracellular voltage changes. RESULTS Light pulses activated ICa,L, with amplitudes similar to voltage-clamp activation and high sensitivity to the L-type Ca2+ channel blocker, nifedipine. Light-triggered ICa,L inactivation exhibited kinetic parameters comparable to voltage-induced inactivation. CONCLUSION OEPC-mediated activation of ICa,L demonstrates their potential for nongenetic optical modulation of cellular physiology potentially paving the way for the development of innovative therapies in cardiovascular health. The integrated model proves the light-mediated activation of ICa,L and advances the understanding of the interplay between the patch-clamp amplifier and external stimulation devices. SIGNIFICANCE Treating cardiac conduction disorders by minimal-invasive means without genetic modifications could advance therapeutic approaches increasing patients' quality of life compared with conventional methods employing electronic devices.
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Shrestha N, Zorn-Pauly K, Mesirca P, Koyani CN, Wölkart G, Di Biase V, Torre E, Lang P, Gorischek A, Schreibmayer W, Arnold R, Maechler H, Mayer B, von Lewinski D, Torrente AG, Mangoni ME, Pelzmann B, Scheruebel S. Lipopolysaccharide-induced sepsis impairs M2R-GIRK signaling in the mouse sinoatrial node. Proc Natl Acad Sci U S A 2023; 120:e2210152120. [PMID: 37406102 PMCID: PMC10334783 DOI: 10.1073/pnas.2210152120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Accepted: 05/15/2023] [Indexed: 07/07/2023] Open
Abstract
Sepsis has emerged as a global health burden associated with multiple organ dysfunction and 20% mortality rate in patients. Numerous clinical studies over the past two decades have correlated the disease severity and mortality in septic patients with impaired heart rate variability (HRV), as a consequence of impaired chronotropic response of sinoatrial node (SAN) pacemaker activity to vagal/parasympathetic stimulation. However, the molecular mechanism(s) downstream to parasympathetic inputs have not been investigated yet in sepsis, particularly in the SAN. Based on electrocardiography, fluorescence Ca2+ imaging, electrophysiology, and protein assays from organ to subcellular level, we report that impaired muscarinic receptor subtype 2-G protein-activated inwardly-rectifying potassium channel (M2R-GIRK) signaling in a lipopolysaccharide-induced proxy septic mouse model plays a critical role in SAN pacemaking and HRV. The parasympathetic responses to a muscarinic agonist, namely IKACh activation in SAN cells, reduction in Ca2+ mobilization of SAN tissues, lowering of heart rate and increase in HRV, were profoundly attenuated upon lipopolysaccharide-induced sepsis. These functional alterations manifested as a direct consequence of reduced expression of key ion-channel components (GIRK1, GIRK4, and M2R) in the mouse SAN tissues and cells, which was further evident in the human right atrial appendages of septic patients and likely not mediated by the common proinflammatory cytokines elevated in sepsis.
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Affiliation(s)
- Niroj Shrestha
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Medical Physics and Biophysics, Medical University of Graz, 8010Graz, Austria
| | - Klaus Zorn-Pauly
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Medical Physics and Biophysics, Medical University of Graz, 8010Graz, Austria
| | - Pietro Mesirca
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, Inserm, 34094Montpellier, France
- Laboratory of Excellence in Ion Channels Science and Therapeutics, 34094Montpellier, France
| | - Chintan N. Koyani
- Division of Cardiology, Medical University of Graz, 8036Graz, Austria
| | - Gerald Wölkart
- Department of Pharmacology and Toxicology, University of Graz, 8010Graz, Austria
| | - Valentina Di Biase
- Institute of Pharmacology, Medical University of Innsbruck, 6020Innsbruck, Austria
| | - Eleonora Torre
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, Inserm, 34094Montpellier, France
- Laboratory of Excellence in Ion Channels Science and Therapeutics, 34094Montpellier, France
| | - Petra Lang
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Medical Physics and Biophysics, Medical University of Graz, 8010Graz, Austria
| | - Astrid Gorischek
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Medical Physics and Biophysics, Medical University of Graz, 8010Graz, Austria
| | - Wolfgang Schreibmayer
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Medical Physics and Biophysics, Medical University of Graz, 8010Graz, Austria
| | - Robert Arnold
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Medical Physics and Biophysics, Medical University of Graz, 8010Graz, Austria
| | - Heinrich Maechler
- Division of Cardiac Surgery, Medical University of Graz, 8036Graz, Austria
| | - Bernd Mayer
- Department of Pharmacology and Toxicology, University of Graz, 8010Graz, Austria
| | - Dirk von Lewinski
- Division of Cardiology, Medical University of Graz, 8036Graz, Austria
| | - Angelo G. Torrente
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, Inserm, 34094Montpellier, France
- Laboratory of Excellence in Ion Channels Science and Therapeutics, 34094Montpellier, France
| | - Matteo E. Mangoni
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, Inserm, 34094Montpellier, France
- Laboratory of Excellence in Ion Channels Science and Therapeutics, 34094Montpellier, France
| | - Brigitte Pelzmann
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Medical Physics and Biophysics, Medical University of Graz, 8010Graz, Austria
| | - Susanne Scheruebel
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Medical Physics and Biophysics, Medical University of Graz, 8010Graz, Austria
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Pelzmann B, Hatab A, Scheruebel S, Langthaler S, Rienmueller T, Sokolowski A, Gorischek A, Platzer D, Zorn-Pauly K, Jahn SW, Bauernhofer T, Schreibmayer W. Consequences of somatic mutations of GIRK1 detected in primary malign tumors on expression and function of G-protein activated, inwardly rectifying, K+ channels. Front Oncol 2022; 12:998907. [DOI: 10.3389/fonc.2022.998907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Accepted: 10/05/2022] [Indexed: 11/13/2022] Open
Abstract
A search in the GDC Data Portal revealed 304 documented somatic mutations of the KCNJ3 gene in primary tumors (out of 10.202 cases). Most affected tumor types were carcinomas from uterus, skin and lung, while breast cancer exerted the lowest number of somatic mutations. We focused our research on 15 missense mutations within the region between TM1 and TM2, comprising the pore helix and ion selectivity signature. Expression was measured by confocal laser scan microscopy of eGFP tagged GIRK1 subunits, expressed with and without GIRK4 in oocytes of Xenopus laevis. GIRK ion currents were activated via coexpressed m2Rs and measured by the Two Electrode Voltage Clamp technique. Magnitude of the total GIRK current, as well as the fraction of current inducible by the agonist, were measured. Ion selectivity was gauged by assessment of the PNa+/PK+ ratio, calculated by the GIRK current reversal potential in extracellular media at different Na+ and K+ concentrations. None of the tested mutations was able to form functional GIRK1 homooligomeric ion channels. One of the mutations, G145A, which locates directly to the ion selectivity signature, exerted an increased PNa+/PK+ ratio. Generally, the missense mutations studied can be categorized into three groups: (i) normal/reduced expression accompanied by reduced/absent function (S132Y, F136L, E139K, G145A, R149Q, R149P, G178D, S185Y, Q186R), (ii) normal/increased expression as well as increased function (E140M, A142T, M184I) and (iii) miniscule expression but increased function relative to expression levels (I151N, G158S). We conclude, that gain of function mutations, identical or similar to categories (ii) and (iii), may potentially be involved in genesis and progression of malignancies in tissues that exert a high rate of occurrence of somatic mutations of KCNJ3.
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Djalinac N, Kolesnik E, Maechler H, Scheruebel-Posch S, Pelzmann B, Rainer PP, Foessl I, Wallner M, Scherr D, Heinemann A, Sedej S, Ljubojevic-Holzer S, von Lewinski D, Bisping E. miR-1183 Is a Key Marker of Remodeling upon Stretch and Tachycardia in Human Myocardium. Int J Mol Sci 2022; 23:ijms23136962. [PMID: 35805966 PMCID: PMC9266684 DOI: 10.3390/ijms23136962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 06/20/2022] [Accepted: 06/21/2022] [Indexed: 11/16/2022] Open
Abstract
Many cardiac insults causing atrial remodeling are linked to either stretch or tachycardia, but a comparative characterization of their effects on early remodeling events in human myocardium is lacking. Here, we applied isometric stretch or sustained tachycardia at 2.5 Hz in human atrial trabeculae for 6 h followed by microarray gene expression profiling. Among largely independent expression patterns, we found a small common fraction with the microRNA miR-1183 as the highest up-regulated transcript (up to 4-fold). Both, acute stretch and tachycardia induced down-regulation of the predicted miR-1183 target genes ADAM20 and PLA2G7. Furthermore, miR-1183 was also significantly up-regulated in chronically remodeled atrial samples from patients with persistent atrial fibrillation (3-fold up-regulation versus sinus rhythm samples), and in ventricular myocardium from dilative cardiomyopathy hearts (2-fold up-regulation) as compared to non-failing controls. In sum, although stretch and tachycardia show distinct transcriptomic signatures in human atrial myocardium, both cardiac insults consistently regulate the expression of miR-1183 and its downstream targets in acute and chronic remodeling. Thus, elevated expression of miR-1183 might serve as a tissue biomarker for atrial remodeling and might be of potential functional significance in cardiac disease.
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Affiliation(s)
- Natasa Djalinac
- Department of Internal Medicine, Division of Cardiology, Medical University of Graz, 8036 Graz, Austria; (N.D.); (E.K.); (P.P.R.); (D.S.); (S.S.); (S.L.-H.); (E.B.)
- Unit of Human Molecular Genetics and Functional Genomics, Department of Biology, University of Padua, 35121 Padua, Italy
| | - Ewald Kolesnik
- Department of Internal Medicine, Division of Cardiology, Medical University of Graz, 8036 Graz, Austria; (N.D.); (E.K.); (P.P.R.); (D.S.); (S.S.); (S.L.-H.); (E.B.)
| | - Heinrich Maechler
- Department of Cardiothoracic Surgery, Medical University of Graz, 8036 Graz, Austria;
| | - Susanne Scheruebel-Posch
- Gottfried Schatz Research Center, Institute of Biophysics, Medical University of Graz, 8010 Graz, Austria; (S.S.-P.); (B.P.)
| | - Brigitte Pelzmann
- Gottfried Schatz Research Center, Institute of Biophysics, Medical University of Graz, 8010 Graz, Austria; (S.S.-P.); (B.P.)
| | - Peter P. Rainer
- Department of Internal Medicine, Division of Cardiology, Medical University of Graz, 8036 Graz, Austria; (N.D.); (E.K.); (P.P.R.); (D.S.); (S.S.); (S.L.-H.); (E.B.)
- BioTechMed Graz, 8036 Graz, Austria
| | - Ines Foessl
- Department of Internal Medicine, Division of Endocrinology and Diabetology, Medical University of Graz, 8010 Graz, Austria;
| | - Markus Wallner
- Department of Internal Medicine, Division of Cardiology, Medical University of Graz, 8036 Graz, Austria; (N.D.); (E.K.); (P.P.R.); (D.S.); (S.S.); (S.L.-H.); (E.B.)
- Cardiovascular Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA
- Correspondence: (M.W.); (D.v.L.); Tel.: +43-316-385-31261 (M.W.); +43-316-385-80684 (D.v.L.)
| | - Daniel Scherr
- Department of Internal Medicine, Division of Cardiology, Medical University of Graz, 8036 Graz, Austria; (N.D.); (E.K.); (P.P.R.); (D.S.); (S.S.); (S.L.-H.); (E.B.)
| | - Akos Heinemann
- Institute of Experimental and Clinical Pharmacology, Medical University of Graz, 8010 Graz, Austria;
| | - Simon Sedej
- Department of Internal Medicine, Division of Cardiology, Medical University of Graz, 8036 Graz, Austria; (N.D.); (E.K.); (P.P.R.); (D.S.); (S.S.); (S.L.-H.); (E.B.)
- BioTechMed Graz, 8036 Graz, Austria
- Institute of Physiology, Faculty of Medicine, University of Maribor, 2000 Maribor, Slovenia
| | - Senka Ljubojevic-Holzer
- Department of Internal Medicine, Division of Cardiology, Medical University of Graz, 8036 Graz, Austria; (N.D.); (E.K.); (P.P.R.); (D.S.); (S.S.); (S.L.-H.); (E.B.)
- BioTechMed Graz, 8036 Graz, Austria
| | - Dirk von Lewinski
- Department of Internal Medicine, Division of Cardiology, Medical University of Graz, 8036 Graz, Austria; (N.D.); (E.K.); (P.P.R.); (D.S.); (S.S.); (S.L.-H.); (E.B.)
- Correspondence: (M.W.); (D.v.L.); Tel.: +43-316-385-31261 (M.W.); +43-316-385-80684 (D.v.L.)
| | - Egbert Bisping
- Department of Internal Medicine, Division of Cardiology, Medical University of Graz, 8036 Graz, Austria; (N.D.); (E.K.); (P.P.R.); (D.S.); (S.S.); (S.L.-H.); (E.B.)
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Koyani CN, Scheruebel S, Jin G, Kolesnik E, Zorn-Pauly K, Mächler H, Hoefler G, von Lewinski D, Heinzel FR, Pelzmann B, Malle E. Hypochlorite-Modified LDL Induces Arrhythmia and Contractile Dysfunction in Cardiomyocytes. Antioxidants (Basel) 2021; 11:25. [PMID: 35052529 PMCID: PMC8772905 DOI: 10.3390/antiox11010025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 12/17/2021] [Accepted: 12/21/2021] [Indexed: 02/05/2023] Open
Abstract
Neutrophil-derived myeloperoxidase (MPO) and its potent oxidant, hypochlorous acid (HOCl), gained attention as important oxidative mediators in cardiac damage and dysfunction. As cardiomyocytes generate low-density lipoprotein (LDL)-like particles, we aimed to identify the footprints of proatherogenic HOCl-LDL, which adversely affects cellular signalling cascades in various cell types, in the human infarcted myocardium. We performed immunohistochemistry for MPO and HOCl-LDL in human myocardial tissue, investigated the impact of HOCl-LDL on electrophysiology and contractility in primary cardiomyocytes, and explored underlying mechanisms in HL-1 cardiomyocytes and human atrial appendages using immunoblot analysis, qPCR, and silencing experiments. HOCl-LDL reduced ICa,L and IK1, and increased INaL, leading to altered action potential characteristics and arrhythmic events including early- and delayed-afterdepolarizations. HOCl-LDL altered the expression and function of CaV1.2, RyR2, NCX1, and SERCA2a, resulting in impaired contractility and Ca2+ homeostasis. Elevated superoxide anion levels and oxidation of CaMKII were mediated via LOX-1 signaling in HL-1 cardiomyocytes. Furthermore, HOCl-LDL-mediated alterations of cardiac contractility and electrophysiology, including arrhythmic events, were ameliorated by the CaMKII inhibitor KN93 and the INaL blocker, ranolazine. This study provides an explanatory framework for the detrimental effects of HOCl-LDL compared to native LDL and cardiac remodeling in patients with high MPO levels during the progression of cardiovascular disease.
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Affiliation(s)
- Chintan N. Koyani
- Division of Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, 8010 Graz, Austria;
- Department of Internal Medicine, Division of Cardiology, Medical University of Graz, 8036 Graz, Austria; (G.J.); (E.K.); (D.v.L.)
| | - Susanne Scheruebel
- Division of Biophysics, Gottfried Schatz Research Center, Medical University of Graz, 8010 Graz, Austria; (S.S.); (K.Z.-P.)
| | - Ge Jin
- Department of Internal Medicine, Division of Cardiology, Medical University of Graz, 8036 Graz, Austria; (G.J.); (E.K.); (D.v.L.)
- The 2nd Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University, Wenzhou 325000, China
| | - Ewald Kolesnik
- Department of Internal Medicine, Division of Cardiology, Medical University of Graz, 8036 Graz, Austria; (G.J.); (E.K.); (D.v.L.)
| | - Klaus Zorn-Pauly
- Division of Biophysics, Gottfried Schatz Research Center, Medical University of Graz, 8010 Graz, Austria; (S.S.); (K.Z.-P.)
| | - Heinrich Mächler
- Department of Surgery, Division of Cardiac Surgery, Medical University of Graz, 8036 Graz, Austria;
| | - Gerald Hoefler
- Diagnostic and Research Center for Molecular BioMedicine, Diagnostic and Research Institute of Pathology, Medical University of Graz, 8010 Graz, Austria;
| | - Dirk von Lewinski
- Department of Internal Medicine, Division of Cardiology, Medical University of Graz, 8036 Graz, Austria; (G.J.); (E.K.); (D.v.L.)
| | - Frank R. Heinzel
- Department of Internal Medicine and Cardiology, Charité-Universitätsmedizin Berlin, Campus Virchow-Klinikum, 13353 Berlin, Germany;
- Deutsches Zentrum für Herz-Kreislauf-Forschung (German Centre for Cardiovascular Research), Partner Site Berlin, 10785 Berlin, Germany
| | - Brigitte Pelzmann
- Division of Biophysics, Gottfried Schatz Research Center, Medical University of Graz, 8010 Graz, Austria; (S.S.); (K.Z.-P.)
| | - Ernst Malle
- Division of Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, 8010 Graz, Austria;
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Langthaler S, Rienmüller T, Scheruebel S, Pelzmann B, Shrestha N, Zorn-Pauly K, Schreibmayer W, Koff A, Baumgartner C. A549 in-silico 1.0: A first computational model to simulate cell cycle dependent ion current modulation in the human lung adenocarcinoma. PLoS Comput Biol 2021; 17:e1009091. [PMID: 34157016 PMCID: PMC8219159 DOI: 10.1371/journal.pcbi.1009091] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 05/18/2021] [Indexed: 11/18/2022] Open
Abstract
Lung cancer is still a leading cause of death worldwide. In recent years, knowledge has been obtained of the mechanisms modulating ion channel kinetics and thus of cell bioelectric properties, which is promising for oncological biomarkers and targets. The complex interplay of channel expression and its consequences on malignant processes, however, is still insufficiently understood. We here introduce the first approach of an in-silico whole-cell ion current model of a cancer cell, in particular of the A549 human lung adenocarcinoma, including the main functionally expressed ion channels in the plasma membrane as so far known. This hidden Markov-based model represents the electrophysiology behind proliferation of the A549 cell, describing its rhythmic oscillation of the membrane potential able to trigger the transition between cell cycle phases, and it predicts membrane potential changes over the cell cycle provoked by targeted ion channel modulation. This first A549 in-silico cell model opens up a deeper insight and understanding of possible ion channel interactions in tumor development and progression, and is a valuable tool for simulating altered ion channel function in lung cancer electrophysiology. Advances in the understanding of functional alterations at genetic, epigenetic or protein expression and the expanding knowledge in mechanisms modulating ion channel kinetics and thus the cells’ bioelectric properties have arisen as promising cancer biomarkers and oncological targets. Our hidden Markov-based in-silico cell model represents the electrophysiology behind proliferation of the A549 cell line, explaining the cell’s rhythmic oscillation from hyperpolarized to depolarized states of the membrane potential, able to trigger the transition between cell cycle phases. The model enables the prediction of membrane potential changes over the cell cycle provoked by targeted modulation of specific ion channels, leading to cell cycle promotion or interruption. We are encouraged that the availability of this first cancer cell model will provide profound insight into possible roles and interactions of ion channels in tumor development and progression, and may aid in the testing of research hypotheses in lung cancer electrophysiology.
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Affiliation(s)
- Sonja Langthaler
- Institute of Health Care Engineering with European Testing Center for Medical Devices, Graz University of Technology, Graz, Austria
- * E-mail: (SL); (TR); (CB)
| | - Theresa Rienmüller
- Institute of Health Care Engineering with European Testing Center for Medical Devices, Graz University of Technology, Graz, Austria
- * E-mail: (SL); (TR); (CB)
| | - Susanne Scheruebel
- Research Unit on Ion Channels and Cancer Biology, Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Medical University of Graz, Graz, Austria
| | - Brigitte Pelzmann
- Research Unit on Ion Channels and Cancer Biology, Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Medical University of Graz, Graz, Austria
| | - Niroj Shrestha
- Research Unit on Ion Channels and Cancer Biology, Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Medical University of Graz, Graz, Austria
| | - Klaus Zorn-Pauly
- Research Unit on Ion Channels and Cancer Biology, Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Medical University of Graz, Graz, Austria
| | - Wolfgang Schreibmayer
- Research Unit on Ion Channels and Cancer Biology, Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Medical University of Graz, Graz, Austria
| | - Andrew Koff
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York City, New York, United States of America
| | - Christian Baumgartner
- Institute of Health Care Engineering with European Testing Center for Medical Devices, Graz University of Technology, Graz, Austria
- * E-mail: (SL); (TR); (CB)
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7
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Schratter G, Scheruebel S, Langthaler S, Ester K, Pelzmann B, Ghaffari-Tabrizi-Wizsy N, Rezania S, Gorischek A, Platzer D, Zorn-Pauly K, Ahammer H, Prokesch A, Stanzer S, Devaney TTJ, Schmidt K, Jahn SW, Prassl R, Bauernhofer T, Schreibmayer W. GIRK1 triggers multiple cancer-related pathways in the benign mammary epithelial cell line MCF10A. Sci Rep 2019; 9:19277. [PMID: 31848385 PMCID: PMC6917815 DOI: 10.1038/s41598-019-55683-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 11/21/2019] [Indexed: 11/20/2022] Open
Abstract
Excessive expression of subunit 1 of GIRK1 in ER+ breast tumors is associated with reduced survival times and increased lymph node metastasis in patients. To investigate possible tumor-initiating properties, benign MCF10A and malign MCF7 mammary epithelial cells were engineered to overexpress GIRK1 neoplasia associated vital parameters and resting potentials were measured and compared to controls. The presence of GIRK1 resulted in resting potentials negative to the controls. Upon GIRK1 overexpression, several cellular pathways were regulated towards pro-tumorigenic action as revealed by comparison of transcriptomes of MCF10AGIRK1 with the control (MCF10AeGFP). According to transcriptome analysis, cellular migration was promoted while wound healing and extracellular matrix interactions were impaired. Vital parameters in MCF7 cells were affected akin the benign MCF10A lines, but to a lesser extent. Thus, GIRK1 regulated cellular pathways in mammary epithelial cells are likely to contribute to the development and progression of breast cancer.
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Affiliation(s)
- Gebhard Schratter
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Medical University of Graz, Graz, Austria
- Research Unit on Ion Channels and Cancer Biology, Medical University of Graz, Graz, Austria
| | - Susanne Scheruebel
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Medical University of Graz, Graz, Austria
- Research Unit on Ion Channels and Cancer Biology, Medical University of Graz, Graz, Austria
| | - Sonja Langthaler
- Institute for Health Care Engineering with European Testing Center of Medical Devices, Graz University of Technology, Graz, Austria
| | - Katja Ester
- Laboratory of Experimental Therapy, Division of Molecular Medicine, Ruđer Bošković Institute, Bijenička 54, 10000, Zagreb, Croatia
| | - Brigitte Pelzmann
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Medical University of Graz, Graz, Austria
- Research Unit on Ion Channels and Cancer Biology, Medical University of Graz, Graz, Austria
| | | | - Simin Rezania
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Medical University of Graz, Graz, Austria
- Research Unit on Ion Channels and Cancer Biology, Medical University of Graz, Graz, Austria
| | - Astrid Gorischek
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Medical University of Graz, Graz, Austria
- Research Unit on Ion Channels and Cancer Biology, Medical University of Graz, Graz, Austria
| | - Dieter Platzer
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Medical University of Graz, Graz, Austria
- Research Unit on Ion Channels and Cancer Biology, Medical University of Graz, Graz, Austria
| | - Klaus Zorn-Pauly
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Medical University of Graz, Graz, Austria
- Research Unit on Ion Channels and Cancer Biology, Medical University of Graz, Graz, Austria
| | - Helmut Ahammer
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Medical University of Graz, Graz, Austria
| | - Andreas Prokesch
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Medical University of Graz, Graz, Austria
- Cell Biology, Histology and Embryology, Medical University of Graz, Graz, Austria
- BioTechMed-Graz, 8010, Graz, Austria
| | - Stefanie Stanzer
- Division of Oncology, Department of Internal Medicine, Medical University of Graz, Graz, Austria
| | - Trevor T J Devaney
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Medical University of Graz, Graz, Austria
- Research Unit on Ion Channels and Cancer Biology, Medical University of Graz, Graz, Austria
| | - Kurt Schmidt
- Institute of Pharmaceutical Sciences, Karl Franzens University of Graz, Graz, Austria
| | - Stephan W Jahn
- Diagnostic & Research Institute of Pathology, Medical University of Graz, Graz, Austria
| | - Ruth Prassl
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Medical University of Graz, Graz, Austria
- Research Unit on Ion Channels and Cancer Biology, Medical University of Graz, Graz, Austria
| | - Thomas Bauernhofer
- Division of Oncology, Department of Internal Medicine, Medical University of Graz, Graz, Austria
- Research Unit on Ion Channels and Cancer Biology, Medical University of Graz, Graz, Austria
| | - Wolfgang Schreibmayer
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Medical University of Graz, Graz, Austria.
- Research Unit on Ion Channels and Cancer Biology, Medical University of Graz, Graz, Austria.
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8
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Kolesnik E, Krainer T, Wallner M, Djalinac N, Verheyen N, Ablasser K, Eaton DM, Rainer PP, Pelzmann B, von Lewinski D. Myocardial GLP-1 Receptor Activation in the Presence of Glucose: Strong Partners. Int J Pept Res Ther 2019. [DOI: 10.1007/s10989-018-9706-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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9
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Koyani CN, Trummer C, Shrestha N, Scheruebel S, Bourgeois B, Plastira I, Kickmaier S, Sourij H, Rainer PP, Madl T, Sattler W, Pelzmann B, Malle E, von Lewinski D. Saxagliptin but Not Sitagliptin Inhibits CaMKII and PKC via DPP9 Inhibition in Cardiomyocytes. Front Physiol 2018; 9:1622. [PMID: 30487758 PMCID: PMC6246635 DOI: 10.3389/fphys.2018.01622] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Accepted: 10/26/2018] [Indexed: 01/18/2023] Open
Abstract
Some oral anti-hyperglycemic drugs, including gliptins that inhibit dipeptidyl peptidase 4 (DPP4), have been linked to the increased risk of heart failure (HF) in type-2 diabetic patients. While the cardiovascular safety trial, TECOS, revealed no link between sitagliptin and the risk of HF, a substantial 27% increase in the hospitalization for HF was observed in type-2 diabetic patients treated with saxagliptin within the SAVOR-TIMI 53 trial. A previous in vitro study revealed that saxagliptin impairs the Ca2+/calmodulin-dependent protein kinase II (CaMKII)-phospholamban (PLB)-sarcoplasmic reticulum Ca2+-ATPase 2a axis and protein kinase C (PKC) activity in cardiomyocytes leading to impaired cardiac contractility and electrophysiological function. However, the link between saxagliptin and its target proteins (CaMKII and PKC) remains to be explored. Since DPP8 and DPP9 (but not DPP4) are expressed by cardiomyocytes and saxagliptin is internalized by cardiomyocytes, we investigated whether DPP8/9 contribute to saxagliptin-mediated inhibition of CaMKII and PKC activity. Structural analysis revealed that the DPP4-saxagliptin interaction motif (S630, Y547) for the cyanopyrrolidine group is conserved in DPP8 (S755, Y669) and DPP9 (S730, Y644). Conversely, F357 that facilitates binding of the anchor lock domain of sitagliptin in the S2 extensive subsite of DPP4 is not conserved in DPP8/9. In parallel, unlike saxagliptin, sitagliptin did not affect phosphorylation of CaMKII/PLB or activity of PKC in HL-1 cardiomyocytes. These findings were recapitulated by pharmacological inhibition (TC-E-5007, a DPP8/9 antagonist) and knock-down of DPP9 (but not DPP8). In primary mouse ventricular cardiomyocytes, saxagliptin (but not sitagliptin) impaired Ca2+ transient relaxation and prolonged action potential duration (APD). These results suggest that saxagliptin-DPP9 interaction impairs the CaMKII-PLB and PKC signaling in cardiomyocytes. We reveal a novel and potential role of DPP9 in cardiac signaling. The interaction of saxagliptin with DPP9 may represent an underlying mechanism for the link between saxagliptin and HF. Elucidation of saxagliptin-DPP9 interaction and downstream events may foster a better understanding of the role of gliptins as modulators of cardiac signaling.
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Affiliation(s)
| | - Christopher Trummer
- Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, Graz, Austria
| | - Niroj Shrestha
- Biophysics, Gottfried Schatz Research Center, Medical University of Graz, Graz, Austria
| | - Susanne Scheruebel
- Biophysics, Gottfried Schatz Research Center, Medical University of Graz, Graz, Austria
| | - Benjamin Bourgeois
- Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, Graz, Austria
| | - Ioanna Plastira
- Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, Graz, Austria
| | - Sandra Kickmaier
- Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, Graz, Austria
| | - Harald Sourij
- Division of Endocrinology and Diabetology, Department of Internal Medicine, Medical University of Graz, Graz, Austria
- Center for Biomarker Research in Medicine, Graz, Austria
| | - Peter P. Rainer
- Division of Cardiology, Medical University of Graz, Graz, Austria
| | - Tobias Madl
- Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, Graz, Austria
- BioTechMed-Graz, Graz, Austria
| | - Wolfgang Sattler
- Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, Graz, Austria
| | - Brigitte Pelzmann
- Biophysics, Gottfried Schatz Research Center, Medical University of Graz, Graz, Austria
| | - Ernst Malle
- Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, Graz, Austria
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10
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Ahammer H, Scheruebel S, Arnold R, Mayrhofer-Reinhartshuber M, Lang P, Dolgos Á, Pelzmann B, Zorn-Pauly K. Sinoatrial Beat to Beat Variability Assessed by Contraction Strength in Addition to the Interbeat Interval. Front Physiol 2018; 9:546. [PMID: 29867582 PMCID: PMC5968354 DOI: 10.3389/fphys.2018.00546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Accepted: 04/27/2018] [Indexed: 12/01/2022] Open
Abstract
Beat to beat variability of cardiac tissue or isolated cells is frequently investigated by determining time intervals from electrode measurements in order to compute scale dependent or scale independent parameters. In this study, we utilize high-speed video camera recordings to investigate the variability of intervals as well as mechanical contraction strengths and relative contraction strengths with nonlinear analyses. Additionally, the video setup allowed us simultaneous electrode registrations of extracellular potentials. Sinoatrial node tissue under control and acetylcholine treated conditions was used to perform variability analyses by computing sample entropies and Higuchi dimensions. Beat to beat interval variabilities measured by the two recording techniques correlated very well, and therefore, validated the video analyses for this purpose. Acetylcholine treatment induced a reduction of beating rate and contraction strength, but the impact on interval variability was negligible. Nevertheless, the variability analyses of contraction strengths revealed significant differences in sample entropies and Higuchi dimensions between control and acetylcholine treated tissue. Therefore, the proposed high-speed video camera technique might represent a non-invasive tool that allows long-lasting recordings for detecting variations in beating behavior over a large range of scales.
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Affiliation(s)
- Helmut Ahammer
- Institute of Biophysics, Medical University of Graz, Graz, Austria
| | | | - Robert Arnold
- Institute of Biophysics, Medical University of Graz, Graz, Austria
| | | | - Petra Lang
- Institute of Biophysics, Medical University of Graz, Graz, Austria
| | - Ádám Dolgos
- Institute for eHealth, Graz University of Applied Sciences, Graz, Austria
| | | | - Klaus Zorn-Pauly
- Institute of Biophysics, Medical University of Graz, Graz, Austria
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11
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Folci A, Steinberger A, Lee B, Stanika R, Scheruebel S, Campiglio M, Ramprecht C, Pelzmann B, Hell JW, Obermair GJ, Heine M, Di Biase V. Molecular mimicking of C-terminal phosphorylation tunes the surface dynamics of Ca V1.2 calcium channels in hippocampal neurons. J Biol Chem 2017; 293:1040-1053. [PMID: 29180451 PMCID: PMC5777246 DOI: 10.1074/jbc.m117.799585] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Revised: 11/03/2017] [Indexed: 11/26/2022] Open
Abstract
L-type voltage-gated CaV1.2 calcium channels (CaV1.2) are key regulators of neuronal excitability, synaptic plasticity, and excitation-transcription coupling. Surface-exposed CaV1.2 distributes in clusters along the dendrites of hippocampal neurons. A permanent exchange between stably clustered and laterally diffusive extra-clustered channels maintains steady-state levels of CaV1.2 at dendritic signaling domains. A dynamic equilibrium between anchored and diffusive receptors is a common feature among ion channels and is crucial to modulate signaling transduction. Despite the importance of this fine regulatory system, the molecular mechanisms underlying the surface dynamics of CaV1.2 are completely unexplored. Here, we examined the dynamic states of CaV1.2 depending on phosphorylation on Ser-1700 and Ser-1928 at the channel C terminus. Phosphorylation at these sites is strongly involved in CaV1.2-mediated nuclear factor of activated T cells (NFAT) signaling, long-term potentiation, and responsiveness to adrenergic stimulation. We engineered CaV1.2 constructs mimicking phosphorylation at Ser-1700 and Ser-1928 and analyzed their behavior at the membrane by immunolabeling protocols, fluorescence recovery after photobleaching, and single particle tracking. We found that the phosphomimetic S1928E variant increases the mobility of CaV1.2 without altering the steady-state maintenance of cluster in young neurons and favors channel stabilization later in differentiation. Instead, mimicking phosphorylation at Ser-1700 promoted the diffusive state of CaV1.2 irrespective of the differentiation stage. Together, these results reveal that phosphorylation could contribute to the establishment of channel anchoring mechanisms depending on the neuronal differentiation state. Finally, our findings suggest a novel mechanism by which phosphorylation at the C terminus regulates calcium signaling by tuning the content of CaV1.2 at signaling complexes.
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Affiliation(s)
- Alessandra Folci
- From the Institute of Biophysics, Medical University of Graz, 8010 Graz, Austria
| | - Angela Steinberger
- From the Institute of Biophysics, Medical University of Graz, 8010 Graz, Austria
| | - Boram Lee
- the Department of Pharmacology, University of California, Davis, California 95616
| | - Ruslan Stanika
- the Department of Physiology and Medical Physics, Medical University of Innsbruck, 6020 Innsbruck, Austria, and
| | - Susanne Scheruebel
- From the Institute of Biophysics, Medical University of Graz, 8010 Graz, Austria
| | - Marta Campiglio
- the Department of Physiology and Medical Physics, Medical University of Innsbruck, 6020 Innsbruck, Austria, and
| | - Claudia Ramprecht
- From the Institute of Biophysics, Medical University of Graz, 8010 Graz, Austria
| | - Brigitte Pelzmann
- From the Institute of Biophysics, Medical University of Graz, 8010 Graz, Austria
| | - Johannes W Hell
- the Department of Pharmacology, University of California, Davis, California 95616
| | - Gerald J Obermair
- the Department of Physiology and Medical Physics, Medical University of Innsbruck, 6020 Innsbruck, Austria, and
| | - Martin Heine
- the Leibniz Institute for Neurobiology, 39118 Magdeburg, Germany
| | - Valentina Di Biase
- From the Institute of Biophysics, Medical University of Graz, 8010 Graz, Austria,
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12
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Bischof H, Rehberg M, Stryeck S, Artinger K, Eroglu E, Waldeck-Weiermair M, Gottschalk B, Rost R, Deak AT, Niedrist T, Vujic N, Lindermuth H, Prassl R, Pelzmann B, Groschner K, Kratky D, Eller K, Rosenkranz AR, Madl T, Plesnila N, Graier WF, Malli R. Novel genetically encoded fluorescent probes enable real-time detection of potassium in vitro and in vivo. Nat Commun 2017; 8:1422. [PMID: 29127288 PMCID: PMC5681659 DOI: 10.1038/s41467-017-01615-z] [Citation(s) in RCA: 92] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Accepted: 10/04/2017] [Indexed: 01/01/2023] Open
Abstract
Changes in intra- and extracellular potassium ion (K+) concentrations control many important cellular processes and related biological functions. However, our current understanding of the spatiotemporal patterns of physiological and pathological K+ changes is severely limited by the lack of practicable detection methods. We developed K+-sensitive genetically encoded, Förster resonance energy transfer-(FRET) based probes, called GEPIIs, which enable quantitative real-time imaging of K+ dynamics. GEPIIs as purified biosensors are suitable to directly and precisely quantify K+ levels in different body fluids and cell growth media. GEPIIs expressed in cells enable time-lapse and real-time recordings of global and local intracellular K+ signals. Hitherto unknown Ca2+-triggered, organelle-specific K+ changes were detected in pancreatic beta cells. Recombinant GEPIIs also enabled visualization of extracellular K+ fluctuations in vivo with 2-photon microscopy. Therefore, GEPIIs are relevant for diverse K+ assays and open new avenues for live-cell K+ imaging. K+ plays an important role in physiology and disease, but the lack of high specificity K+ sensors limits our understanding of its spatiotemporal dynamics. Here the authors develop genetically-encoded FRET-based probes able to quantify K+ concentration in body fluids, cells and specific organelles.
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Affiliation(s)
- Helmut Bischof
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010, Graz, Austria
| | - Markus Rehberg
- Ludwig-Maximilians University (LMU), Institute for Stroke and Dementia Research (ISD), Klinikum der Universität München, Feodor-Lynen-Straße 17, 81377, Munich, Germany
| | - Sarah Stryeck
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010, Graz, Austria
| | - Katharina Artinger
- Clinical Division of Nephrology, Medical University of Graz, Auenbruggerplatz 27, 8036, Graz, Austria
| | - Emrah Eroglu
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010, Graz, Austria
| | - Markus Waldeck-Weiermair
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010, Graz, Austria
| | - Benjamin Gottschalk
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010, Graz, Austria
| | - Rene Rost
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010, Graz, Austria
| | - Andras T Deak
- Clinical Division of Nephrology, Medical University of Graz, Auenbruggerplatz 27, 8036, Graz, Austria
| | - Tobias Niedrist
- Clinical Institute of Medical and Chemical Laboratory Diagnostics, Medical University of Graz, Auenbruggerplatz 27, 8036, Graz, Austria
| | - Nemanja Vujic
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010, Graz, Austria
| | - Hanna Lindermuth
- Institute of Biophysics, Medical University of Graz, Neue Stiftingtalstraße 6/4, 8010, Graz, Austria
| | - Ruth Prassl
- Institute of Biophysics, Medical University of Graz, Neue Stiftingtalstraße 6/4, 8010, Graz, Austria
| | - Brigitte Pelzmann
- Institute of Biophysics, Medical University of Graz, Neue Stiftingtalstraße 6/4, 8010, Graz, Austria
| | - Klaus Groschner
- Institute of Biophysics, Medical University of Graz, Neue Stiftingtalstraße 6/4, 8010, Graz, Austria
| | - Dagmar Kratky
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010, Graz, Austria.,BioTechMed-Graz, Graz, Austria
| | - Kathrin Eller
- Clinical Division of Nephrology, Medical University of Graz, Auenbruggerplatz 27, 8036, Graz, Austria
| | - Alexander R Rosenkranz
- Clinical Division of Nephrology, Medical University of Graz, Auenbruggerplatz 27, 8036, Graz, Austria
| | - Tobias Madl
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010, Graz, Austria.,BioTechMed-Graz, Graz, Austria
| | - Nikolaus Plesnila
- Ludwig-Maximilians University (LMU), Institute for Stroke and Dementia Research (ISD), Klinikum der Universität München, Feodor-Lynen-Straße 17, 81377, Munich, Germany
| | - Wolfgang F Graier
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010, Graz, Austria.,BioTechMed-Graz, Graz, Austria
| | - Roland Malli
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010, Graz, Austria. .,BioTechMed-Graz, Graz, Austria.
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13
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Wölkart G, Schrammel A, Koyani CN, Scherübel S, Zorn-Pauly K, Malle E, Pelzmann B, Andrä M, Ortner A, Mayer B. Cardioprotective effects of 5-hydroxymethylfurfural mediated by inhibition of L-type Ca 2+ currents. Br J Pharmacol 2017; 174:3640-3653. [PMID: 28768052 PMCID: PMC5610158 DOI: 10.1111/bph.13967] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Revised: 07/11/2017] [Accepted: 07/14/2017] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND AND PURPOSE The antioxidant 5-hydroxymethylfurfural (5-HMF) exerts documented beneficial effects in several experimental pathologies and is currently tested as an antisickling drug in clinical trials. In the present study, we examined the cardiovascular effects of 5-HMF and elucidated the mode of action of the drug. EXPERIMENTAL APPROACH The cardiovascular effects of 5-HMF were studied with pre-contracted porcine coronary arteries and rat isolated normoxic-perfused hearts. Isolated hearts subjected to ischaemia/reperfusion (I/R) injury were used to test for potential cardioprotective effects of the drug. The effects of 5-HMF on action potential and L-type Ca2+ current (ICa,L ) were studied by patch-clamping guinea pig isolated ventricular cardiomyocytes. KEY RESULTS 5-HMF relaxed coronary arteries in a concentration-dependent manner and exerted negative inotropic, lusitropic and chronotropic effects in rat isolated perfused hearts. On the other hand, 5-HMF improved recovery of inotropic and lusitropic parameters in isolated hearts subjected to I/R. Patch clamp experiments revealed that 5-HMF inhibits L-type Ca2+ channels. Reduced ICa,L density, shift of ICa,L steady-state inactivation curves toward negative membrane potentials and slower recovery of ICa,L from inactivation in response to 5-HMF accounted for the observed cardiovascular effects. CONCLUSIONS AND IMPLICATIONS Our data revealed a cardioprotective effect of 5-HMF in I/R that is mediated by inhibition of L-type Ca2+ channels. Thus, 5-HMF is suggested as a beneficial additive to cardioplegic solutions, but adverse effects and contraindications of Ca2+ channel blockers have to be considered in therapeutic application of the drug.
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Affiliation(s)
- G Wölkart
- Institute of Pharmaceutical Sciences, Department of Pharmacology and Toxicology, University of Graz, Graz, Austria
| | - A Schrammel
- Institute of Pharmaceutical Sciences, Department of Pharmacology and Toxicology, University of Graz, Graz, Austria
| | - C N Koyani
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - S Scherübel
- Institute of Biophysics, Medical University of Graz, Graz, Austria
| | - K Zorn-Pauly
- Institute of Biophysics, Medical University of Graz, Graz, Austria
| | - E Malle
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - B Pelzmann
- Institute of Biophysics, Medical University of Graz, Graz, Austria
| | - M Andrä
- Department of Thoracic and Cardiovascular Surgery, Klinikum Klagenfurt, Klagenfurt, Austria
| | - A Ortner
- Institute of Pharmaceutical Sciences, Department of Pharmaceutical Chemistry, University of Graz, Graz, Austria
| | - B Mayer
- Institute of Pharmaceutical Sciences, Department of Pharmacology and Toxicology, University of Graz, Graz, Austria
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14
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Scheruebel S, Koyani C, Lang P, Bernhart E, Hallstroem S, Maechler H, Plank G, Zorn-Pauly K, Pelzmann B. P1707Interatrial differences in AF remodelling. Europace 2017. [DOI: 10.1093/ehjci/eux161.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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15
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Eroglu E, Gottschalk B, Charoensin S, Blass S, Bischof H, Rost R, Madreiter-Sokolowski CT, Pelzmann B, Bernhart E, Sattler W, Hallström S, Malinski T, Waldeck-Weiermair M, Graier WF, Malli R. Development of novel FP-based probes for live-cell imaging of nitric oxide dynamics. Nat Commun 2016; 7:10623. [PMID: 26842907 PMCID: PMC4743004 DOI: 10.1038/ncomms10623] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 01/05/2016] [Indexed: 12/22/2022] Open
Abstract
Nitric oxide () is a free radical with a wide range of biological effects, but practically impossible to visualize in single cells. Here we report the development of novel multicoloured fluorescent quenching-based probes by fusing a bacteria-derived -binding domain close to distinct fluorescent protein variants. These genetically encoded probes, referred to as geNOps, provide a selective, specific and real-time read-out of cellular dynamics and, hence, open a new era of bioimaging. The combination of geNOps with a Ca(2+) sensor allowed us to visualize and Ca(2+) signals simultaneously in single endothelial cells. Moreover, targeting of the probes was used to detect signals within mitochondria. The geNOps are useful new tools to further investigate and understand the complex patterns of signalling on the single (sub)cellular level.
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Affiliation(s)
- Emrah Eroglu
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, Harrachgasse 21/III, 8010 Graz, Austria
| | - Benjamin Gottschalk
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, Harrachgasse 21/III, 8010 Graz, Austria
| | - Suphachai Charoensin
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, Harrachgasse 21/III, 8010 Graz, Austria
| | - Sandra Blass
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, Harrachgasse 21/III, 8010 Graz, Austria
| | - Helmut Bischof
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, Harrachgasse 21/III, 8010 Graz, Austria
| | - Rene Rost
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, Harrachgasse 21/III, 8010 Graz, Austria
| | - Corina T Madreiter-Sokolowski
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, Harrachgasse 21/III, 8010 Graz, Austria
| | - Brigitte Pelzmann
- Institute of Biophysics, Center of Physiological Medicine, Medical University of Graz, Harrachgasse 21/IV, 8010 Graz, Austria
| | - Eva Bernhart
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, Harrachgasse 21/III, 8010 Graz, Austria
| | - Wolfgang Sattler
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, Harrachgasse 21/III, 8010 Graz, Austria
| | - Seth Hallström
- Institute of Physiological Chemistry, Center of Physiological Medicine, Medical University of Graz, Harrachgasse 21/II, 8010 Graz, Austria
| | - Tadeusz Malinski
- Nanomedical Research Laboratory, Department of Chemistry and Biochemistry, Ohio University, 350 West State Street, Athens, Ohio 45701, USA
| | - Markus Waldeck-Weiermair
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, Harrachgasse 21/III, 8010 Graz, Austria
| | - Wolfgang F Graier
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, Harrachgasse 21/III, 8010 Graz, Austria
| | - Roland Malli
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, Harrachgasse 21/III, 8010 Graz, Austria
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16
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Trescher K, Dzilic E, Kreibich M, Gasser H, Aumayr K, Kerjaschki D, Pelzmann B, Hallström S, Podesser BK. The nitric oxide donor, S-nitroso human serum albumin, as an adjunct to HTK-N cardioplegia improves protection during cardioplegic arrest after myocardial infarction in rats. Interact Cardiovasc Thorac Surg 2014; 20:387-94. [PMID: 25468794 DOI: 10.1093/icvts/ivu383] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
OBJECTIVES Currently available cardioplegic solutions provide excellent protection in patients with normal surgical risk; in high-risk patients, however, such as in emergency coronary artery bypass surgery, there is still room for improvement. As most of the cardioplegic solutions primarily protect myocytes, the addition of substances for protection of the endothelium might improve their protective potential. The nitric oxide donor, S-nitroso human serum albumin (S-NO-HSA), which has been shown to prevent endothelial nitric oxide synthase uncoupling, was added to the newly developed histidine-tryptophan-ketoglutarat (HTK-N) cardioplegia in an isolated heart perfusion system after subjecting rats to acute myocardial infarction (MI) and reperfusion. METHODS In male Sprague-Dawley rats, acute MI was induced by ligation for 1 h of the anterior descending coronary artery. After 2 h of in vivo reperfusion hearts were evaluated on an isolated erythrocyte-perfused working heart model. Cold ischaemia (4°C) for 60 min was followed by 45 min of reperfusion. Cardiac arrest was induced either with HTK (n = 10), HTK-N (n = 10) or HTK-N + S-NO-HSA (n = 10). In one group (HTK-N + S-NO-HSA plus in vivo S-NO-HSA; n = 9) an additional in vivo infusion of S-NO-HSA was performed. RESULTS Post-ischaemic recovery of cardiac output (HTK: 77 ± 4%, HTK-N: 86 ± 7%, HTK-N + S-NO-HSA: 101 ± 5%, in vivo S-NO-HSA: 93 ± 8%), external heart work (HTK: 79 ± 5%, HTK-N: 83 ± 3%, HTK-N + S-NO-HSA: 101 ± 8%, in vivo S-NO-HSA: 109 ± 13%), coronary flow (HTK: 77 ± 4%, HTK-N: 94 ± 6%, HTK-N + S-NO-HSA: 118 ± 15%, in vivo S-NO-HSA: 113 ± 3.17%) [HTK-N + S-NO-HSA vs HTK P < 0.001; HTK-N + S-NO-HSA vs HTK-N P < 0.05] and left atrial diastolic pressure (HTK: 122 ± 31%, HTK-N: 159 ± 43%, HTK-N + S-NO-HSA: 88 ± 30, in vivo S-NO-HSA: 62 ± 10%) [HTK-N + S-NO-HSA vs HTK P < 0.05; in vivo S-NO-HSA vs HTK-N P < 0.05] were significantly improved in both S-NO-HSA-treated groups compared with HTK and HTK-N, respectively. This was accompanied by better preservation of high-energy phosphates (adenosine triphosphate; energy charge) and ultrastructural integrity on transmission electron microscopy. However, no additional benefit of in vivo S-NO-HSA infusion was observed. CONCLUSIONS Addition of the NO donor, S-NO-HSA refines the concept of HTK-N cardioplegia in improving post-ischaemic myocardial perfusion. HTK-N with S-NO-HSA is a possible therapeutic option for patients who have to be operated on for acute MI.
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Affiliation(s)
- Karola Trescher
- Department of Cardiac Surgery, LK St. Pölten, Pölten, Austria Ludwig Boltzmann Cluster for Cardiovascular Research, Vienna Medical University, Vienna, Austria
| | - Elda Dzilic
- Ludwig Boltzmann Cluster for Cardiovascular Research, Vienna Medical University, Vienna, Austria
| | - Maximilian Kreibich
- Ludwig Boltzmann Cluster for Cardiovascular Research, Vienna Medical University, Vienna, Austria
| | - Harald Gasser
- Ludwig Boltzmann Cluster for Cardiovascular Research, Vienna Medical University, Vienna, Austria
| | - Klaus Aumayr
- Department of Pathology, Vienna Medical University, Vienna, Austria
| | | | - Brigitte Pelzmann
- Institute of Biophysics, Center of Physiological Medicine, Medical University Graz, Graz, Austria
| | - Seth Hallström
- Institute of Physiological Chemistry, Center of Physiological Medicine, Medical University Graz, Graz, Austria
| | - Bruno K Podesser
- Department of Cardiac Surgery, LK St. Pölten, Pölten, Austria Ludwig Boltzmann Cluster for Cardiovascular Research, Vienna Medical University, Vienna, Austria
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Ahammer H, Scherubel S, Arnold R, Zorn-Pauly K, Pelzmann B. Beat to beat variability of embryonic chick heart cells under septic conditions: application and evaluation of entropy as well as fractal measures. Annu Int Conf IEEE Eng Med Biol Soc 2013; 2013:5566-9. [PMID: 24110998 DOI: 10.1109/embc.2013.6610811] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Extracardiac factors of heart rate variability have commonly been investigated using linear and nonlinear methods for a long time. Recently, intracardiac mechanisms on an electrophysiological basis have been found to be also important. This work is focused on the evaluation of complex measures of temporal signals gained with microelectrode measurements of embryonic chick heart aggregates. Septic conditions were mimicked in vitro by lipopolysaccharide (LPS) administration in order to investigate the influence on beat to beat variability. Surrogate data analysis revealed high statistical significances for normalized complexity measures.
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Pelzmann B, Zorn-Pauly K, Hallström S, Mächler H, Jakubowski A, Lang P, Koidl B. Effects of thienopyridines and thienopyrimidinones on L-type calcium current in isolated cardiomyocytes. Naunyn Schmiedebergs Arch Pharmacol 2010; 382:433-40. [DOI: 10.1007/s00210-010-0557-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2010] [Accepted: 08/25/2010] [Indexed: 12/15/2022]
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Platzer D, Pelzmann B, Zorn-Pauly K. Using Fluorescence Optical Mapping to Investigate the Electrophysiological Effects of Thienopyridines at the Tissue Level on Guinea Pig Papillary Muscle during Shock Induced Potential Changes. Biophys J 2010. [DOI: 10.1016/j.bpj.2009.12.2885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Huber S, Pelzmann B, Hallström S, Marte W, Mächler H, Koidl B. Does NADH supplementation protect the heart against reperfusion injury. Thorac Cardiovasc Surg 2008. [DOI: 10.1055/s-2008-1038022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Zorn-Pauly K, Pelzmann B, Lang P, Mächler H, Schmidt H, Ebelt H, Werdan K, Koidl K, Mueller-Werdan U. Endotoxin impairs the human pacemaker current If. Crit Care 2008. [PMCID: PMC4088619 DOI: 10.1186/cc6469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Zorn-Pauly K, Pelzmann B, Lang P, Mächler H, Schmidt H, Ebelt H, Werdan K, Koidl B, Müller-Werdan U. Endotoxin impairs the human pacemaker current If. Shock 2007; 28:655-661. [PMID: 18092381] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
LPSs trigger the development of sepsis by gram-negative bacteria and cause a variety of biological effects on host cells, including alterations on ionic channels. Because heart rate variability is reduced in human sepsis and endotoxemia, we hypothesized that LPS affects the pacemaker current I(f) in human heart, which might--at least in part--explain this phenomenon. Isolated human myocytes from right atrial appendages were incubated for 6 to 10 h with LPS (1 and 10 microg/mL) and afterwards used to investigate the pacemaker current I(f). I(f) was measured with the whole-cell patch-clamp technique (at 37 degrees C). Incubation of atrial myocytes with 10 microg/mL LPS was found to significantly impair I(f) by suppressing the current at membrane potentials positive to -80 mV and slowing down current activation, but without effecting maximal current conductance. Furthermore, in incubated cells (10 microg/mL), the response of I(f) to [beta]-adrenergic stimulation (1 microM isoproterenol) was significantly larger compared with control cells (shift of half-maximal activation voltage to more positive potentials amounted to -10 and -14 mV in untreated and treated cells, respectively). Simulations using a spontaneously active sinoatrial cell model demonstrated that LPS-induced I(f) impairment reduced the responsiveness of the model cell to fluctuations of autonomic input. This study showed a direct impact of LPS on the cardiac pacemaker current I(f). The LPS-induced I(f) impairment may contribute to the clinically observed reduction in heart rate variability under septic conditions and in cardiac diseases such as heart failure, where endotoxin can be of pathophysiological relevance.
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Affiliation(s)
- Klaus Zorn-Pauly
- Institut für Biophysik, Zentrum für Physiologische Medizin, Medizinische Universität Graz, Harrachgasse 21, Graz, Austria
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Greinix HT, Faé I, Schneider B, Rosenmayr A, Mitterschiffthaler A, Pelzmann B, Kalhs P, Lechner K, Mayr WR, Fischer GF. Impact of HLA class I high-resolution mismatches on chronic graft-versus-host disease and survival of patients given hematopoietic stem cell grafts from unrelated donors. Bone Marrow Transplant 2005; 35:57-62. [PMID: 15531903 DOI: 10.1038/sj.bmt.1704741] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
There is consensus that matching of unrelated donors (URD) and patients for HLA class II alleles improves the outcome of hematopoietic stem cell transplantation (HSCT). However, the significance of HLA class I allelic mismatches for transplant outcome is under discussion and reports on long-term effects like chronic graft-versus-host disease (GVHD) are rare. Thus, we investigated the association of human leukocyte antigen (HLA) class I allele mismatches and outcome in 144 patients given HSCT from URD who were matched for HLA-DRB1, DRB3/4/5, and DQB1 alleles. The risk of chronic GVHD was significantly increased in patients with class I mismatched donors, the mismatch either detected by low- or high-resolution typing. A single HLA class I allele mismatch significantly increased the risk of chronic GVHD in multivariate analysis. Overall survival was significantly reduced in patient/donor pairs with more than one-allele class I mismatch. Thus, selection of unrelated donors for transplantation should be based on high-resolution HLA class I typing.
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Affiliation(s)
- H T Greinix
- Department of Medicine I, Bone Marrow Transplantation, Medical University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna, Austria.
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Krogh-Madsen T, Schaffer P, Skriver AD, Taylor LK, Pelzmann B, Koidl B, Guevara MR. An ionic model for rhythmic activity in small clusters of embryonic chick ventricular cells. Am J Physiol Heart Circ Physiol 2005; 289:H398-413. [PMID: 15708964 DOI: 10.1152/ajpheart.00683.2004] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We recorded transmembrane potential in whole cell recording mode from small clusters (2-4 cells) of spontaneously beating 7-day embryonic chick ventricular cells after 1-3 days in culture and investigated effects of the blockers D-600, diltiazem, almokalant, and Ba2+. Electrical activity in small clusters is very different from that in reaggregates of several hundred embryonic chick ventricular cells, e.g., TTX-sensitive fast upstrokes in reaggregates vs. TTX-insensitive slow upstrokes in small clusters (maximum upstroke velocity approximately 100 V/s vs. approximately 10 V/s). On the basis of our voltage- and current-clamp results and data from the literature, we formulated a Hodgkin-Huxley-type ionic model for the electrical activity in these small clusters. The model contains a Ca2+ current (ICa), three K+ currents (IKs, IKr, and IK1), a background current, and a seal-leak current. ICa generates the slow upstroke, whereas IKs, IKr, and IK1 contribute to repolarization. All the currents contribute to spontaneous diastolic depolarization, e.g., removal of the seal-leak current increases the interbeat interval from 392 to 535 ms. The model replicates the spontaneous activity in the clusters as well as the experimental results of application of blockers. Bifurcation analysis and simulations with the model predict that annihilation and single-pulse triggering should occur with partial block of ICa. Embryonic chick ventricular cells have been used as an experimental model to investigate various aspects of spontaneous beating of cardiac cells, e.g., mutual synchronization, regularity of beating, and spontaneous initiation and termination of reentrant rhythms; our model allows investigation of these topics through numerical simulation.
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Affiliation(s)
- Trine Krogh-Madsen
- Dept. of Physiology, McGill University, 3655 Sir William Osler Promenade, Montreal, Quebec H3G 1Y6, Canada
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Zorn-Pauly K, Schaffer P, Pelzmann B, Bernhart E, Wei G, Lang P, Ledinski G, Greilberger J, Koidl B, Jürgens G. Oxidized LDL induces ventricular myocyte damage and abnormal electrical activity--role of lipid hydroperoxides. Cardiovasc Res 2005; 66:74-83. [PMID: 15769450 DOI: 10.1016/j.cardiores.2004.12.009] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2004] [Revised: 11/25/2004] [Accepted: 12/14/2004] [Indexed: 11/16/2022] Open
Abstract
OBJECTIVE It was our aim to investigate effects of human LDL, copper-, or AAPH-oxidized over different periods of time to different degrees (ox-LDL), on viability and electrophysiological parameters of isolated ventricular myocytes of guinea pigs. METHODS Guinea pig ventricular myocytes were incubated with ox-LDL or native LDL (at 0.5 mg/ml) for 12 h, and afterwards myocyte damage, action potentials, and transmembrane ion currents were studied (at 37 degrees C). RESULTS Ox-LDL was found to induce severe myocyte damage, whereas native LDL had no effect. Myocyte damage was dependent on the content of total lipid hydroperoxides in both copper-oxidized and AAPH-oxidized LDL. Incubation with ox-LDL led to intense contractile and electrophysiological effects including prolongation of action potential duration, depolarization of resting membrane potential, spontaneous activity, generation of afterdepolarizations, and modification of transmembrane ion currents (e.g. inward rectifier, calcium, and background currents). CONCLUSIONS Ox-LDL induced cell damage and irregular electrical activity in ventricular myocytes. These effects were dependent on the lipid hydroperoxide content of ox-LDL and were similar to oxidative stress (OS) induced by various OS-generating systems. The observed effects may play a role for functional cardiac abnormalities in patients with increased ox-LDL levels.
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Affiliation(s)
- Klaus Zorn-Pauly
- Center of Physiological Medicine, Institute of Biophysics, Medical University Graz, Harrachgasse 21/4, A-8010 Graz, Austria
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Zorn-Pauly K, Schaffer P, Pelzmann B, Lang P, Mächler H, Rigler B, Koidl B. in left human atrium: a potential contributor to atrial ectopy. Cardiovasc Res 2004; 64:250-9. [PMID: 15485684 DOI: 10.1016/j.cardiores.2004.07.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2004] [Revised: 06/30/2004] [Accepted: 07/01/2004] [Indexed: 11/17/2022] Open
Abstract
OBJECTIVE The left human atrium plays an important role in initiation of atrial fibrillation (AF) and the hyperpolarization activated cation current (I(f)) is a candidate for contributing to abnormal automaticity. However, electrophysiological data concerning I(f) are not available in this cardiac region and we therefore investigated I(f) in human left atrial tissue. METHODS Human atrial myocytes were isolated from the left atrial appendage (LAA) and the left atrial wall (LAW) obtained from patients undergoing open heart surgery. I(f) was measured with the whole-cell patch-clamp technique. RESULTS I(f) densities between -70 and -110 mV were found to be significantly higher in LAA than in LAW cells. Furthermore, in the group of LAA cells the half maximal activation potential (V(1/2)) was found to be less negative (V(1/2) of -84.3+/-1.9 mV, n=14/9) compared to LAW cells (V(1/2) of -97.8+/-2.1 mV, n=28/9). Beta-adrenergic receptor stimulation with isoproterenol (1 microM) caused an acceleration of current activation and a V(1/2) shift to more positive potentials in cells of both regions (LAA: 8.8+/-2.3 mV, n=6/4 and LAW: 8.9+/-2.6 mV, n=6/4). Simulations using a mathematical model of the human atrial myocyte demonstrated that I(f) was able to induce spontaneous activity in the model at a regular rhythm due to the interplay of I(f), Na(+)/Ca(2+) exchange current and Ca(2+) release of the sarcoplasmic reticulum (SR). CONCLUSIONS Our study revealed the presence of I(f) in left atrial myocytes and showed that I(f) parameters depend on atrial region. I(f) current densities were sufficient to convert the mathematical model of a quiescent human atrial cell into a "pacemaker cell". These data support the hypothesis of I(f) as a contributor to abnormal automaticity in human atrial tissue.
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Affiliation(s)
- Klaus Zorn-Pauly
- Institut für Medizinische Physik und Biophysik, Medizinische Universität Graz, Harrachgasse 21, A-8010 Graz, Austria
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Zorn-Pauly K, Schaffer P, Pelzmann B, Bernhart E, Lang P, Koidl B. L-type and T-type Ca2+ current in cultured ventricular guinea pig myocytes. Physiol Res 2004. [DOI: 10.33549/physiolres.930495] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The aim of this investigation was to study L-type and T-type Ca2+ current (ICaL and ICaT) in short-term cultured adult guinea pig ventricular myocytes. The isolated myocytes were suspended in serum-supplemented medium up to 5 days. Using whole-cell patch clamp techniques ICaL and ICaT were studied by applying voltage protocols from different holding potentials (–40 and –90 mV). After 5 days in culture the myocytes still showed their typical rod shaped morphology but a decline in cell membrane capacitance (26 %). The peak density of ICaT was reduced significantly between day 0 (–1.60.37 pA/pF, n=9) and day 5 (–0.40.13 pA/pF, n=11), whereas peak ICaL density revealed no significant differences during culturing. The ICaT/ICaL ratio dropped from 0.13 at day 0 to 0.05 at day 5. Compared with day 0 ICaL the steady state inactivation curve of day 1, day 3 and day 5 myocytes was slightly shifted to more negative potentials. Our data indicate that guinea pig ventricular L-type and T-type Ca2+ channels are differently regulated in culture.
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Zorn-Pauly K, Schaffer P, Pelzmann B, Bernhart E, Lang P, Koidl B. L-type and T-type Ca2+ current in cultured ventricular guinea pig myocytes. Physiol Res 2004; 53:369-77. [PMID: 15311995] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/30/2023] Open
Abstract
The aim of this investigation was to study L-type and T-type Ca(2+) current (I(CaL) and I(CaT)) in short-term cultured adult guinea pig ventricular myocytes. The isolated myocytes were suspended in serum-supplemented medium up to 5 days. Using whole-cell patch clamp techniques ICaL and ICaT were studied by applying voltage protocols from different holding potentials (-40 and -90 mV). After 5 days in culture the myocytes still showed their typical rod shaped morphology but a decline in cell membrane capacitance (26 %). The peak density of ICaT was reduced significantly between day 0 (-1.6+/-0.37 pA/pF, n=9) and day 5 (-0.4+/-0.13 pA/pF, n=11), whereas peak ICaL density revealed no significant differences during culturing. The I(CaT)/I(CaL) ratio dropped from 0.13 at day 0 to 0.05 at day 5. Compared with day 0 I(CaL) the steady state inactivation curve of day 1, day 3 and day 5 myocytes was slightly shifted to more negative potentials. Our data indicate that guinea pig ventricular L-type and T-type Ca(2+) channels are differently regulated in culture.
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Affiliation(s)
- K Zorn-Pauly
- Institut für Mediziniche Physik und Biophysik, Universität Graz, Harrachgasse 21, A-8010 Graz, Austria
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Zorn-Pauly K, Schaffer P, Pelzmann B, Bernhart E, Lang P, Zink M, Mächler H, Rigler B, Koidl B. A hyperpolarization activated inward current (If) is present in infant ventricular myocytes. Basic Res Cardiol 2003; 98:362-6. [PMID: 14556081 DOI: 10.1007/s00395-003-0424-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2003] [Revised: 05/06/2003] [Accepted: 06/03/2003] [Indexed: 10/26/2022]
Abstract
I(f) was shown to be present in adult human atrial and ventricular myocytes but data obtained from infant myocytes are lacking. We have studied I(f) in isolated ventricular myocytes from children undergoing surgical correction of tetralogy of Fallot (TOF; n = 5; mean age: 15.3 months). All recordings were made with the patch clamp technique in the whole cell mode at a temperature of 36-37 degrees C. A modified Tyrode solution containing 25 mM KCl was used to amplify I(f). Considering I(f) to be present when its current density at -120 mV was greater than 0.5 pA/pF, I(f) could be found in 28 out of 32 myocytes (88%). The mean current density was -2.01 +/- 0.3 pA/pF (mean +/- S.E.M.). First current activation occurred at -70 mV and I(f) could be reversibly inhibited by superfusing the myocytes with CsCl (2 mM). Half maximal activation (V(1/2)) of I(f) was at -80.3 +/- 1.0 mV (n = 28). Beta-adrenergic receptor stimulation with isoproterenol (1 microM) caused an acceleration of current activation and a shift of V(1/2) by 7.88 +/- 1.8 mV (n = 10) to less negative potentials. This study provides first evidence that the hyperpolarization-activated pacemaker current I(f) is present in infant human ventricular myocytes. Our results suggest that I(f) in ventricle of infants suffering from TOF has similar properties as I(f) in adult ventricle.
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Affiliation(s)
- Klaus Zorn-Pauly
- Institut für Medizinische Physik und Biophysik, Universität Graz, Harrachgasse 21, 8010 Graz, Austria
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Pelzmann B, Hallström S, Schaffer P, Lang P, Nadlinger K, Birkmayer GD, Vrecko K, Reibnegger G, Koidl B. NADH supplementation decreases pinacidil-primed I K ATP in ventricular cardiomyocytes by increasing intracellular ATP. Br J Pharmacol 2003; 139:749-54. [PMID: 12812998 PMCID: PMC1573896 DOI: 10.1038/sj.bjp.0705300] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
1 The aim of this study was to investigate the effect of nicotinamide-adenine dinucleotide (NADH) supplementation on the metabolic condition of isolated guinea-pig ventricular cardiomyocytes. The pinacidil-primed ATP-dependent potassium current I(K(ATP)) was used as an indicator of subsarcolemmal ATP concentration and intracellular adenine nucleotide contents were measured. 2 Membrane currents were studied using the patch-clamp technique in the whole-cell recording mode at 36-37 degrees C. Adenine nucleotides were determined by HPLC. 3 Under physiological conditions (4.3 mM ATP in the pipette solution, ATP(i)) I(K(ATP)) did not contribute to basal electrical activity. 4 The ATP-dependent potassium (K((ATP))) channel opener pinacidil activated I(K(ATP)) dependent on [ATP](i) showing a significantly more pronounced activation at lower (1 mM) [ATP](i). 5 Supplementation of cardiomyocytes with 300 micro g ml(-1) NADH (4-6 h) resulted in a significantly reduced I(K(ATP)) activation by pinacidil compared to control cells. The current density was 13.8+/-3.78 (n=6) versus 28.9+/-3.38 pA pF(-1) (n=19; P<0.05). 6 Equimolar amounts of the related compounds nicotinamide and NAD(+) did not achieve a similar effect like NADH. 7 Measurement of adenine nucleotides by HPLC revealed a significant increase in intracellular ATP (NADH supplementation: 45.6+/-1.88 nmol mg(-1) protein versus control: 35.4+/-2.57 nmol mg(-1) protein, P<0.000005). 8 These data show that supplementation of guinea-pig ventricular cardiomyocytes with NADH results in a decreased activation of I(K(ATP)) by pinacidil compared to control myocytes, indicating a higher subsarcolemmal ATP concentration. 9 Analysis of intracellular adenine nucleotides by HPLC confirmed the significant increase in ATP.
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Affiliation(s)
- Brigitte Pelzmann
- Institut für Medizinische Physik und Biophysik, Karl-Franzens-Universität Graz, Harrachgasse 21, A-8010 Graz, Austria
| | - Seth Hallström
- Department of Research and Development, Birkmayer Laboratories, Schwarzspanierstraße 15, A-1090 Wien, Austria
| | - Peter Schaffer
- Institut für Medizinische Physik und Biophysik, Karl-Franzens-Universität Graz, Harrachgasse 21, A-8010 Graz, Austria
| | - Petra Lang
- Institut für Medizinische Physik und Biophysik, Karl-Franzens-Universität Graz, Harrachgasse 21, A-8010 Graz, Austria
| | - Karl Nadlinger
- Department of Research and Development, Birkmayer Laboratories, Schwarzspanierstraße 15, A-1090 Wien, Austria
| | - George D Birkmayer
- Department of Research and Development, Birkmayer Laboratories, Schwarzspanierstraße 15, A-1090 Wien, Austria
| | - Karoline Vrecko
- Institut für Medizinische Chemie und Pregl Laboratorium, Karl-Franzens-Universität Graz, Harrachgasse 21, A-8010 Graz, Austria
| | - Gilbert Reibnegger
- Institut für Medizinische Chemie und Pregl Laboratorium, Karl-Franzens-Universität Graz, Harrachgasse 21, A-8010 Graz, Austria
| | - Bernd Koidl
- Institut für Medizinische Physik und Biophysik, Karl-Franzens-Universität Graz, Harrachgasse 21, A-8010 Graz, Austria
- Author for correspondence:
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Pelzmann B, Schaffer P, Bernhart E, Lang P, Mächler H, Rigler B, Koidl B. Effects of K+ channel openers on I K(ATP) of human atrial myocytes at physiological temperatures. Naunyn Schmiedebergs Arch Pharmacol 2001; 363:125-32. [PMID: 11218064 DOI: 10.1007/s002100000323] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The aim of this study was to investigate the effects of the potassium channel openers (PCOs) cromakalim and pinacidil on the ATP-dependent potassium current I(K)(ATP) in human atrial myocytes. Cells were isolated from the right atrial appendage obtained during cardiac surgery. Membrane currents were studied with the patch-clamp technique in the whole-cell recording mode at 36 degrees -37 degrees C. Under physiological conditions (4.3 mmol/l ATP in the pipette solution, ATPi) I(K)(ATP) did not contribute to basal electrical activity. When ATPi was omitted from the pipette solution I(K)(ATP) activated with a time lag of 4.92+/-0.92 min (n=6) and was completely inhibited by glibenclamide. Using 4.3 mmol/l ATPi I(K)(ATP) at +30 mV was increased by 2.04+/-0.51, 7.24+/-1.65 and 13.22+/-3.71 pA/pF (n=7) with 10, 30 and 100 micromol/l cromakalim, respectively, and by 3.24+/-0.98 (n=6), 4.07+/-0.48 (n=10) and 3.46+/-1.23 pA/pF (n=6) with 10, 30 and 100 micromol/l pinacidil, respectively. Control current density was 5.39+/-0.47 pA/pF (n=39). Using 1 mmol/l ATPi I(K)(ATP) showed a more pronounced activation (4.81+/-3.28, n=6; 9.78+/-2.60, n=7; and 15.1+/-4.18 pA/pF, n=6; with 10, 30 and 100 micromol/l pinacidil, respectively). I(K)(ATP) activated by both compounds could be effectively inhibited by glibenclamide. Repetitive exposure to pinacidil (30 micromol/l at 4.3 mmol/l ATPi) caused a potentiation of I(K)(ATP). Current density at +30 mV was increased by 87% during the first and by 401% during the second pinacidil application (n=5). The data presented in this paper provide new information about electrophysiological characteristics of human atrial I(K)(ATP) and its modulation by the PCOs cromakalim and pinacidil and suggest species-dependent differences.
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Affiliation(s)
- B Pelzmann
- Institut für Medizinische Physik und Biophysik, Karl-Franzens-Universität, Graz, Austria.
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Schaffer P, Pelzmann B, Bernhart E, Lang P, Mächler H, Rigler B, Koidl B. The sulphonylurea glibenclamide inhibits voltage dependent potassium currents in human atrial and ventricular myocytes. Br J Pharmacol 1999; 128:1175-80. [PMID: 10578129 PMCID: PMC1571749 DOI: 10.1038/sj.bjp.0702904] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
1 It was the aim of our study to investigate the effects of the sulphonylurea glibenclamide on voltage dependent potassium currents in human atrial myocytes. 2 The drug blocked a fraction of the quasi steady state current (ramp response) which was activated positive to -20 mV, was sensitive to 4-aminopyridine (500 microM) and was different from the ATP dependent potassium current IK(ATP). 3 Glibenclamide dose dependently inhibited both, the peak as well as the late current elicited by step depolarization positive to -20 mV. The IC50 for reduction in charge area of total outward current was 76 microM. 4 The double-exponential inactivation time-course of the total outward current was accelerated in the presence of glibenclamide with a tau(fast) of 12.7+/-1.5 ms and a tau(slow) of 213+/-25 ms in control and 5.8+/-1.9 ms (P<0.001) and 101+/-20 ms (P<0.05) under glibenclamide (100 microM). 5 Our data suggest, that both repolarizing currents in human atrial myocytes, the transient outward current (Ito1) and the ultrarapid delayed rectifier current (IKur) were inhibited by glibenclamide. 6 In human ventricular myocytes glibenclamide inhibited Ito1 without affecting the late current. 7 Our data suggest that glibenclamide inhibits human voltage dependent cardiac potassium currents at concentrations above 10 microM.
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Affiliation(s)
- P Schaffer
- Institut für Medizinische Physik und Biophysik, Karl-Franzens-Universität Graz, Harrachgasse 21, A-8010, Graz, Austria.
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Schaffer P, Pelzmann B, Bernhart E, Lang P, Mächler H, Rigler B, Koidl B. Repolarizing currents in ventricular myocytes from young patients with tetralogy of Fallot. Cardiovasc Res 1999; 43:332-43. [PMID: 10536663 DOI: 10.1016/s0008-6363(99)00118-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
OBJECTIVE It was the aim of our study to describe repolarizing currents in ventricular myocytes isolated from children with tetralogy of Fallot. This is the first report on outward currents in ventricular myocytes from children. METHODS Ventricular myocytes were isolated from tissue samples of the outflow tract of the right ventricle which were obtained during corrective surgery of tetralogy of Fallot. Action potentials and whole-cell currents were recorded with the patch clamp technique at a temperature of 36-37 degrees C. RESULTS The mean resting potential was -71.7 +/- 1.92 mV, action potential amplitude was 110 +/- 2.96 mV and action potential duration at 90% repolarization was 794 +/- 99.5 ms (n = 12). In four out of 12 myocytes early afterdepolarizations (EADs) were observed. Upon hyperpolarization Ba(2+)-sensitive inward currents similar to the inward rectifier current (IKl) could be observed. The current density at -120 mV was -22.8 +/- 2.47 pA/pF (n = 14). A transient outward current (Itol) could be recorded in all myocytes studied, the current density varied from 0.3 to 8.6 pA/pF with a mean of 3.77 +/- 0.47 pA/pF at +40 mV (n = 38). Recovery of Itol from inactivation was fast (70% recovery within 100 ms), rate-dependent reduction amounted to 38.2% at 4 Hz. A delayed rectifier current was seen in only two out of 38 myocytes (rapid component IKr). CONCLUSIONS The electrophysiological characteristics of right ventricular myocytes isolated from children with tetralogy of Fallot resemble in most cases subendocardial myocytes from adults. The most prominent difference is a fast recovery from inactivation as well as a small rate dependent reduction of Itol. The observed EADs may have clinical implications.
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Affiliation(s)
- P Schaffer
- Institut für Medizinische Physik und Biophysik, Universität Graz, Austria.
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Schaffer P, Pelzmann B, Bernhart E, Lang P, Løkebø JE, Mächler H, Rigler B, Koidl B. Estimation of outward currents in isolated human atrial myocytes using inactivation time course analysis. Pflugers Arch 1998; 436:457-68. [PMID: 9644230 DOI: 10.1007/s004240050657] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The aim was to investigate outward currents in single, isolated, human, atrial myocytes and to determine the relative contribution of individual current components to the total outward current. Currents were recorded using the whole-cell patch-clamp technique at 36-37 degreesC. Individual outward current components were estimated from recordings of total outward current using a mathematical procedure based on the inactivation time course of the respective currents. This method allows estimation of outward currents without the use of drugs or conditioning voltage-clamp protocols to suppress individual current components. A rapidly activating and partially inactivating total outward current was recorded when myocytes were voltage clamped at potentials positive to -20 mV (peak current density 24. 0+/-0.97 pA/pF at +40 mV; n=107 cells, 33 patients). This total outward current comprised three overlapping currents: a rapidly inactivating, transient, outward current (Ito1) a slowly and partially inactivating current (ultrarapid delayed rectifier, IKur) and a third current component which most probably reflects a non selective cation current (not characterized). The average current densities at +40 mV were 8.92+/-0.44 pA/pF for Ito1 and 15.1+/-0.72 pA/pF for IKur (n=107 cells). Recovery from inactivation was bi-exponential for both currents and was faster for Ito1. A slowly activating delayed rectifier current (IK) was not found. The current densities of peak Ito1 and IKur varied strongly between individual myocytes, even in those from the same patient. The ratio IKur/Ito1 was 0.5-6.9 with a mean of 1.98+/-0.11 (n=107 cells), suggesting that IKur is the main repolarizing current. The amplitudes of the total outward current, Ito1 and IKur, and the ratio of the latter two were independent of patient age (16-87 years).
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Affiliation(s)
- P Schaffer
- Institut für Medizinische Physik und Biophysik, Karl-Franzens-Unsiversität Graz, Harrachgasse 21, A-8010 Graz, Austria
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Pelzmann B, Schaffer P, Bernhart E, Lang P, Mächler H, Rigler B, Koidl B. L-type calcium current in human ventricular myocytes at a physiological temperature from children with tetralogy of Fallot. Cardiovasc Res 1998; 38:424-32. [PMID: 9709403 DOI: 10.1016/s0008-6363(98)00002-9] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
OBJECTIVE The aim was to investigate the electrophysiological properties of the L-type calcium current (ICa,L) in ventricular myocytes at a physiological temperature (36-37 degrees C) isolated from children undergoing surgical repair of tetralogy of Fallot. METHODS ICa,L was recorded with the patch-clamp technique in the single electrode whose-cell mode at a physiological calcium concentration (1.8 mmol/l) at 36-37 degrees C. RESULTS Under these conditions, maximum current density averaged -5.80 +/- 0.45 pA/pF. ICa,L showed a bell-shaped current-voltage relationship: the current activated at -37.7 +/- 1.36 mV, peaked at +9.41 +/- 1.60 mV and reversed at +57.7 +/- 2.12 mV (n = 17). At +10 mV, time to peak of ICa,L was 5.23 +/- 0.46 ms. Membrane potentials for half-maximal steady-state activation and inactivation of ICa,L were -6.02 and -20.4 mV, respectively, the slope factors were 7.16 mV for steady-state activation and 6.49 mV for steady-state inactivation. ICa,L did not completely inactivate and showed a big window current between -45 and +40 mV. The inactivation of ICa,L showed a biexponential time course with a fast time constant ranging from 9.11 to 12.9 ms and a slow time constant ranging from 60.9 to 220 ms between -30 and +30 mV. Only the slow time constant showed a pronounced voltage dependency. The recovery from inactivation of ICa,L was biphasic with a fast time constant of 60.7 ms and a slow time constant of 619 ms. beta-Adrenergic stimulation with isoprenaline (1 mumol/l) increased the ICa,L density from -5.71 +/- 1.55 to -13.8 +/- 1.96 pA/pF (142%; P < 0.05) at +10 mV. CONCLUSIONS The present study demonstrates that most of the electrophysiological properties of ICa,L in ventricular myocytes isolated from children with tetralogy of Fallot resemble those of adult ventricular cells. The existence of a big calcium window current could be involved in the occurrence of early afterdepolarizations which could lead to the high incidence of arrhythmias after surgical repair of tetralogy of Fallot.
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Affiliation(s)
- B Pelzmann
- Institut für Medizinische Physik and Biophysik, Karl-Franzens-Universität, Graz, Austria.
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Porciatti F, Pelzmann B, Cerbai E, Schaffer P, Pino R, Bernhart E, Koidl B, Mugelli A. The pacemaker current I(f) in single human atrial myocytes and the effect of beta-adrenoceptor and A1-adenosine receptor stimulation. Br J Pharmacol 1997; 122:963-9. [PMID: 9384516 PMCID: PMC1565023 DOI: 10.1038/sj.bjp.0701473] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
1. We used single human atrial myocytes to study I(f) occurrence, properties and pharmacological modulation. Cells were obtained by chunk enzymatic digestion from samples of right atrial appendages of patients undergoing corrective cardiac surgery. 2. Patch-clamped cells in the whole-cell configuration were superfused with a modified Tyrode solution to reduce contamination by interfering currents and to amplify I(f). The average cell membrane capacitance was 85.06+/-2.41 pF (n=531). Data were consistent with the geometrical dimensions of the cells (length 94.2+/-1.89 microm, width 17.9+/-0.42 microm, n=126). 3. When hyperpolarizing to -120 mV from a holding potential of -40 mV, 252 of 306 tested cells (82%) expressed a hyperpolarization-activated inward current (I(f) density=3.77+/-0.25 pA pF(-1)); the current was considered to be present in a given cell if its density at -120 mV was larger than 0.5 pA pF(-1). 4. Current activation was sigmoidal and fitted a Boltzmann model; the average activation curve (n=25) showed a maximum current amplitude of 205.97+/-19.94 pA, corresponding to 3.87+/-0.63 pA pF(-1), voltage of half-maximal activation (V(1/2)) at -86.68+/-2.19 mV and a slope of -11.39+/-0.69 mV. The reversal potential of I(f) measured by tail-current analysis was -13.07+/-1.92 mV (n=6). The addition of CsCl (5 mM) fully and reversibly blocked the current. 5. In the presence of the beta-adrenoceptor agonist isoprenaline (Iso, 1 microM), V(1/2) was significantly shifted toward less negative potentials by 6.06+/-1.96 mV (n=16, P=0.0039). The selective A1-adenosine receptor agonist cyclopentyladenosine (CPA, 1 microM) caused a statistically significant shift of V(1/2) toward more negative potentials with respect to the control curve, both in the absence (-7.37+/-1.83 mV, P=0.0005, n=11) and in the presence of 1 microM Iso (-4.97+/-1.78, P=0.031, n=6). 6. These results demonstrate that a current with the properties of I(f) described in cardiac primary and secondary pacemakers occurs in the majority of human atrial cells. While the pathophysiological relevance of I(f) in human atrial tissue remains to be defined, our data clearly show that it is modulated through stimulation of beta-adrenoceptors and A1-adenosine receptors.
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Affiliation(s)
- F Porciatti
- Department of Pharmacology, University of Firenze, Italy
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Koidl B, Flaschberger P, Schaffer P, Pelzmann B, Bernhart E, Mächler H, Rigler B. Effects of the class III antiarrhythmic drug ambasilide on outward currents in human atrial myocytes. Naunyn Schmiedebergs Arch Pharmacol 1996; 353:226-32. [PMID: 8717164 DOI: 10.1007/bf00168761] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
We have studied the inhibitory influence of the class III antiarrhythmic drug ambasilide (LU 47110) on the transient outward current Ito1 and the sustained current Iso following inactivation of Ito1, in human atrial myocytes. The two currents are separated by a mathematical procedure based on the amplitudes and time constants of the biexponential inactivation of the total outward current. The frequency dependence, the recovery from inactivation and the kinetics of activation and inactivation are described. Ambasilide reversibly and concentration dependently inhibited Ito1, Iso and the sodium current INa. Concentration required for half maximal inhibition (IC50) for the effects on Ito1 and Iso were 23.3 mumol/l and 45.7 mumol/l respectively, concentrations shown by others to be effective in terminating and preventing fibrillation in a dog atrial arrhythmia model. Ambasilide not only reduced the amplitude of Ito1 and Iso but also accelerated the time course of inactivation from 14.22 to 6.69 ms and from 202.3 to 87.9 ms respectively. The amplitude of Ito1 showed only a small dependence on stimulation frequency characteristic for human atrial myocytes, whereas Iso was reduced significantly at higher stimulation frequencies. Ambasilide did not change these relationships (0.1-4 Hz) and therefore did not show the reverse use-dependence known from other class III antiarrhythmic agents and which is an important property for a prospective antiarrhythmic drug. The lack of an effect of ambasilide on both steady-state activation and inactivation of Ito1, and the time constant of recovery from inactivation, suggests that ambasilide acts by changing conductance rather than by influencing the gating mechanism. The described characteristics make ambasilide an interesting substance in the group of class III antiarrhythmic drugs.
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Affiliation(s)
- B Koidl
- Institut für Medizinische Physik und Biophysik, Universität Graz, Austria
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Pelzmann B, Schaffer P, Mächler H, Rigler B, Koidl B. Adenosine inhibits the L-type calcium current in human atrial myocytes. Naunyn Schmiedebergs Arch Pharmacol 1995; 351:293-7. [PMID: 7609783 DOI: 10.1007/bf00233249] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The effects of adenosine on the L-type Ca2+ current (Ica) were studied in human atrial myocytes using the whole-cell voltage clamp technique. Ica was recorded under physiological calcium concentrations (1.8 mmol/l) at 37 degrees C. Under these conditions the current density of basal Ica averaged 4.0 pA/pF. Isoprenaline (1 mumol/l) increased basal Ica to 249.7%. Adenosine (100 mumol/l) in the presence of isoprenaline (1 mumol/l) decreased Ica from the level obtained with isoprenaline to 87.5% of basal Ica. Adenosine (0.1 to 100 mumol/l) also reduced basal Ica, maximally to 64.5% of control. Activation and inactivation parameters of basal Ica were not significantly different between adenosine (100 mumol/l) and control recordings. Our results show that adenosine affects both basal and isoprenaline stimulated Ica in human atrial myocytes. Although a considerable decrease of basal Ica was seen, we conclude that the action of adenosine on L-type Ca2+ current in human atrial myocytes is mainly antiadrenergic. Both effects may contribute to the antiarrhythmic properties of adenosine.
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Affiliation(s)
- B Pelzmann
- Institut für Medizinische Physik und Biophysik, Universität Graz, Austria
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Abstract
The influence of an isotonic, alkaline saline solution (diluted "Emser Sole" or brine from the spa of Bad Ems) on the ciliary beat of isolated cultured human ciliated cells of the upper respiratory tract was investigated. The ciliary beat was observed via an inverted phase contrast microscope (Zeiss Axiomat IDPC) and measured microphotometrically under physiological conditions and after the damaging influence of 1% propanal solution. Under physiological conditions the saline solution had a positive, although statistically not significant influence on the frequency of the ciliary beat. After damage of the cultivated cells by 1% propanal solution, the saline solution had a significant better influence on the regeneration of the cultured cells than a physiological sodium chloride solution. It is concluded that diluted brine from Bad Ems has a positive effect on the ciliary beat of the respiratory epithelium and accelerates its regeneration after damage by viral and bacterial infections, surgery or inhaled noxae.
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Affiliation(s)
- G Wolf
- Universitäts-HNO-Klinik, Karl-Franzens-Universität Graz
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