1
|
Hohendanner F, Boegner M, Huettemeister J, Zhang K, Dreysse S, Knosalla C, Falk V, Schoenrath F, Just IA, Stawowy P. Microvascular dysfunction in heart transplantation is associated with altered cardiomyocyte mitochondrial structure and unimpaired excitation-contraction coupling. PLoS One 2024; 19:e0303540. [PMID: 38820336 PMCID: PMC11142617 DOI: 10.1371/journal.pone.0303540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Accepted: 04/25/2024] [Indexed: 06/02/2024] Open
Abstract
INTRODUCTION Microvascular dysfunction (MVD) is a hallmark feature of chronic graft dysfunction in patients that underwent orthotopic heart transplantation (OHT) and is the main contributor to impaired long-term graft survival. The aim of this study was to determine the effect of MVD on functional and structural properties of cardiomyocytes isolated from ventricular biopsies of OHT patients. METHODS We included 14 patients post-OHT, who had been transplanted for 8.1 years [5.0; 15.7 years]. Mean age was 49.6 ± 14.3 years; 64% were male. Coronary microvasculature was assessed using guidewire-based coronary flow reserve(CFR)/index of microvascular resistance (IMR) measurements. Ventricular myocardial biopsies were obtained and cardiomyocytes were isolated using enzymatic digestion. Cells were electrically stimulated and subcellular Ca2+ signalling as well as mitochondrial density were measured using confocal imaging. RESULTS MVD measured by IMR was present in 6 of 14 patients with a mean IMR of 53±10 vs. 12±2 in MVD vs. controls (CTRL), respectively. CFR did not differ between MVD and CTRL. Ca2+ transients during excitation-contraction coupling in isolated ventricular cardiomyocytes from a subset of patients showed unaltered amplitudes. In addition, Ca2+ release and Ca2+ removal were not significantly different between MVD and CTRL. However, mitochondrial density was significantly increased in MVD vs. CTRL (34±1 vs. 29±2%), indicating subcellular changes associated with MVD. CONCLUSION In-vivo ventricular microvascular dysfunction post OHT is associated with preserved excitation-contraction coupling in-vitro, potentially owing to compensatory changes on the mitochondrial level or due to the potentially reversible cause of the disease.
Collapse
Affiliation(s)
- Felix Hohendanner
- Department of Cardiology, Deutsches Herzzentrum der Charité, Angiology and Intensive Care Medicine, Berlin, Germany
- Charité –Universitätsmedizin Berlin, Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), Berlin, Germany
| | - Markus Boegner
- Department of Cardiology, Deutsches Herzzentrum der Charité, Angiology and Intensive Care Medicine, Berlin, Germany
- Charité –Universitätsmedizin Berlin, Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), Berlin, Germany
| | - Judith Huettemeister
- Department of Cardiology, Deutsches Herzzentrum der Charité, Angiology and Intensive Care Medicine, Berlin, Germany
- Charité –Universitätsmedizin Berlin, Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), Berlin, Germany
| | - Kun Zhang
- Department of Cardiology, Deutsches Herzzentrum der Charité, Angiology and Intensive Care Medicine, Berlin, Germany
- Charité –Universitätsmedizin Berlin, Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), Berlin, Germany
| | - Stephan Dreysse
- Department of Cardiology, Deutsches Herzzentrum der Charité, Angiology and Intensive Care Medicine, Berlin, Germany
- Charité –Universitätsmedizin Berlin, Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
| | - Christoph Knosalla
- Charité –Universitätsmedizin Berlin, Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), Berlin, Germany
- Department of Cardiothoracic and Vascular Surgery, Deutsches Herzzentrum der Charité, Berlin, Germany
| | - Volkmar Falk
- Charité –Universitätsmedizin Berlin, Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), Berlin, Germany
- Department of Cardiothoracic and Vascular Surgery, Deutsches Herzzentrum der Charité, Berlin, Germany
- Department of Health Sciences and Technology, Swiss Federal Institute of Technology (ETH), Institute of Translational Medicine, Translational Cardiovascular Technologies, Zurich, Switzerland
| | - Felix Schoenrath
- Charité –Universitätsmedizin Berlin, Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), Berlin, Germany
- Department of Cardiothoracic and Vascular Surgery, Deutsches Herzzentrum der Charité, Berlin, Germany
| | - Isabell Anna Just
- Charité –Universitätsmedizin Berlin, Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), Berlin, Germany
- Department of Cardiothoracic and Vascular Surgery, Deutsches Herzzentrum der Charité, Berlin, Germany
| | - Philipp Stawowy
- Department of Cardiology, Deutsches Herzzentrum der Charité, Angiology and Intensive Care Medicine, Berlin, Germany
- Charité –Universitätsmedizin Berlin, Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), Berlin, Germany
| |
Collapse
|
2
|
Oropeza-Almazán Y, Blatter LA. Role of Mitochondrial ROS for Calcium Alternans in Atrial Myocytes. Biomolecules 2024; 14:144. [PMID: 38397381 PMCID: PMC10887423 DOI: 10.3390/biom14020144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2023] [Revised: 01/19/2024] [Accepted: 01/19/2024] [Indexed: 02/25/2024] Open
Abstract
Atrial calcium transient (CaT) alternans is defined as beat-to-beat alternations in CaT amplitude and is causally linked to atrial fibrillation (AF). Mitochondria play a significant role in cardiac excitation-contraction coupling and Ca signaling through redox environment regulation. In isolated rabbit atrial myocytes, ROS production is enhanced during CaT alternans, measured by fluorescence microscopy. Exogenous ROS (tert-butyl hydroperoxide) enhanced CaT alternans, whereas ROS scavengers (dithiothreitol, MnTBAP, quercetin, tempol) alleviated CaT alternans. While the inhibition of cellular NADPH oxidases had no effect on CaT alternans, interference with mitochondrial ROS (ROSm) production had profound effects: (1) the superoxide dismutase mimetic MitoTempo diminished CaT alternans and shifted the pacing threshold to higher frequencies; (2) the inhibition of cyt c peroxidase by SS-31, and inhibitors of ROSm production by complexes of the electron transport chain S1QEL1.1 and S3QEL2, decreased the severity of CaT alternans; however (3) the impairment of mitochondrial antioxidant defense by the inhibition of nicotinamide nucleotide transhydrogenase with NBD-Cl and thioredoxin reductase-2 with auranofin enhanced CaT alternans. Our results suggest that intact mitochondrial antioxidant defense provides crucial protection against pro-arrhythmic CaT alternans. Thus, modulating the mitochondrial redox state represents a potential therapeutic approach for alternans-associated arrhythmias, including AF.
Collapse
Affiliation(s)
| | - Lothar A. Blatter
- Department of Physiology and Biophysics, Rush University Medical Center, 1750 W. Harrison St., Chicago, IL 60612, USA;
| |
Collapse
|
3
|
Mehrhof F, Hüttemeister J, Tanacli R, Bock M, Bögner M, Schoenrath F, Falk V, Zips D, Hindricks G, Gerds-Li JH, Hohendanner F. Cardiac radiotherapy transiently alters left ventricular electrical properties and induces cardiomyocyte-specific ventricular substrate changes in heart failure. Europace 2023; 26:euae005. [PMID: 38193546 PMCID: PMC10803027 DOI: 10.1093/europace/euae005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Accepted: 12/28/2023] [Indexed: 01/10/2024] Open
Abstract
AIMS Ongoing clinical trials investigate the therapeutic value of stereotactic cardiac radioablation (cRA) in heart failure patients with ventricular tachycardia. Animal data indicate an effect on local cardiac conduction properties. However, the exact mechanism of cRA in patients remains elusive. Aim of the current study was to investigate in vivo and in vitro myocardial properties in heart failure and ventricular tachycardia upon cRA. METHODS AND RESULTS High-density 3D electroanatomic mapping in sinus rhythm was performed in a patient with a left ventricular assist device and repeated ventricular tachycardia episodes upon several catheter-based endocardial radio-frequency ablation attempts. Subsequent to electroanatomic mapping and cRA of the left ventricular septum, two additional high-density electroanatomic maps were obtained at 2- and 4-month post-cRA. Myocardial tissue samples were collected from the left ventricular septum during 4-month post-cRA from the irradiated and borderzone regions. In addition, we performed molecular biology and mitochondrial density measurements of tissue and isolated cardiomyocytes. Local voltage was altered in the irradiated region of the left ventricular septum during follow-up. No change of local voltage was observed in the control (i.e. borderzone) region upon irradiation. Interestingly, local activation time was significantly shortened upon irradiation (2-month post-cRA), a process that was reversible (4-month post-cRA). Molecular biology unveiled an increased expression of voltage-dependent sodium channels in the irradiated region as compared with the borderzone, while Connexin43 and transforming growth factor beta were unchanged (4-month post-cRA). Moreover, mitochondrial density was decreased in the irradiated region as compared with the borderzone. CONCLUSION Our study supports the notion of transiently altered cardiac conduction potentially related to structural and functional cellular changes as an underlying mechanism of cRA in patients with ventricular tachycardia.
Collapse
Affiliation(s)
- Felix Mehrhof
- Klinik für Radioonkologie und Strahlentherapie, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Judith Hüttemeister
- Department of Cardiology, Angiology and Intensive Care Medicine, Deutsches Herzzentrum der Charité, Augustenburger Platz 1, Germany, 13353 Berlin, Germany
- Charité—Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Radu Tanacli
- Department of Cardiology, Angiology and Intensive Care Medicine, Deutsches Herzzentrum der Charité, Augustenburger Platz 1, Germany, 13353 Berlin, Germany
- Charité—Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Matthias Bock
- Department of Cardiology, Angiology and Intensive Care Medicine, Deutsches Herzzentrum der Charité, Augustenburger Platz 1, Germany, 13353 Berlin, Germany
- Charité—Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Charitéplatz 1, 10117 Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), partner site, Berlin, Germany
| | - Markus Bögner
- Department of Cardiology, Angiology and Intensive Care Medicine, Deutsches Herzzentrum der Charité, Augustenburger Platz 1, Germany, 13353 Berlin, Germany
- Charité—Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Charitéplatz 1, 10117 Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), partner site, Berlin, Germany
| | - Felix Schoenrath
- Charité—Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Charitéplatz 1, 10117 Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), partner site, Berlin, Germany
- Klinik für Herz-, Thorax- und Gefäßchirurgie, Deutsches Herzzentrum der Charité, Berlin, Germany
| | - Volkmar Falk
- Charité—Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Charitéplatz 1, 10117 Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), partner site, Berlin, Germany
- Klinik für Herz-, Thorax- und Gefäßchirurgie, Deutsches Herzzentrum der Charité, Berlin, Germany
- Translational Cardiovascular Technologies, Institute of Translational Medicine, Department of Health Sciences and Technology, Swiss Federal Institute of Technology (ETH) Zurich, Berlin, Germany
| | - Daniel Zips
- Klinik für Radioonkologie und Strahlentherapie, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Gerhard Hindricks
- Department of Cardiology, Angiology and Intensive Care Medicine, Deutsches Herzzentrum der Charité, Augustenburger Platz 1, Germany, 13353 Berlin, Germany
- Charité—Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Charitéplatz 1, 10117 Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), partner site, Berlin, Germany
| | - Jin-Hong Gerds-Li
- Department of Cardiology, Angiology and Intensive Care Medicine, Deutsches Herzzentrum der Charité, Augustenburger Platz 1, Germany, 13353 Berlin, Germany
- Charité—Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Felix Hohendanner
- Department of Cardiology, Angiology and Intensive Care Medicine, Deutsches Herzzentrum der Charité, Augustenburger Platz 1, Germany, 13353 Berlin, Germany
- Charité—Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Charitéplatz 1, 10117 Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), partner site, Berlin, Germany
| |
Collapse
|
4
|
Kiessling M, Djalinac N, Voglhuber J, Ljubojevic-Holzer S. Nuclear Calcium in Cardiac (Patho)Physiology: Small Compartment, Big Impact. Biomedicines 2023; 11:biomedicines11030960. [PMID: 36979939 PMCID: PMC10046765 DOI: 10.3390/biomedicines11030960] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Accepted: 03/17/2023] [Indexed: 03/30/2023] Open
Abstract
The nucleus of a cardiomyocyte has been increasingly recognized as a morphologically distinct and partially independent calcium (Ca2+) signaling microdomain, with its own Ca2+-regulatory mechanisms and important effects on cardiac gene expression. In this review, we (1) provide a comprehensive overview of the current state of research on the dynamics and regulation of nuclear Ca2+ signaling in cardiomyocytes, (2) address the role of nuclear Ca2+ in the development and progression of cardiac pathologies, such as heart failure and atrial fibrillation, and (3) discuss novel aspects of experimental methods to investigate nuclear Ca2+ handling and its downstream effects in the heart. Finally, we highlight current challenges and limitations and recommend future directions for addressing key open questions.
Collapse
Affiliation(s)
- Mara Kiessling
- Department of Cardiology, Medical University of Graz, 8036 Graz, Austria
| | - Nataša Djalinac
- Department of Biology, University of Padua, 35122 Padova, Italy
| | - Julia Voglhuber
- Department of Cardiology, Medical University of Graz, 8036 Graz, Austria
- BioTechMed Graz, 8010 Graz, Austria
| | - Senka Ljubojevic-Holzer
- Department of Cardiology, Medical University of Graz, 8036 Graz, Austria
- BioTechMed Graz, 8010 Graz, Austria
- Gottfried Schatz Research Center, Division of Molecular Biology and Biochemistry, Medical University of Graz, 8010 Graz, Austria
| |
Collapse
|
5
|
Hohendanner F, Prabhu A, Wilck N, Stangl V, Pieske B, Stangl K, Althoff TF. G q-Mediated Arrhythmogenic Signaling Promotes Atrial Fibrillation. Biomedicines 2023; 11:biomedicines11020526. [PMID: 36831062 PMCID: PMC9953645 DOI: 10.3390/biomedicines11020526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 02/07/2023] [Accepted: 02/09/2023] [Indexed: 02/16/2023] Open
Abstract
BACKGROUND Atrial fibrillation (AF) is promoted by various stimuli like angiotensin II, endothelin-1, epinephrine/norepinephrine, vagal activation, or mechanical stress, all of which activate receptors coupled to G-proteins of the Gαq/Gα11-family (Gq). Besides pro-fibrotic and pro-inflammatory effects, Gq-mediated signaling induces inositol trisphosphate receptor (IP3R)-mediated intracellular Ca2+ mobilization related to delayed after-depolarisations and AF. However, direct evidence of arrhythmogenic Gq-mediated signaling is absent. METHODS AND RESULTS To define the role of Gq in AF, transgenic mice with tamoxifen-inducible, cardiomyocyte-specific Gαq/Gα11-deficiency (Gq-KO) were created and exposed to intracardiac electrophysiological studies. Baseline electrophysiological properties, including heart rate, sinus node recovery time, and atrial as well as AV nodal effective refractory periods, were comparable in Gq-KO and control mice. However, inducibility and mean duration of AF episodes were significantly reduced in Gq-KO mice-both before and after vagal stimulation. To explore underlying mechanisms, left atrial cardiomyocytes were isolated from Gq-KO and control mice and electrically stimulated to study Ca2+-mobilization during excitation-contraction coupling using confocal microscopy. Spontaneous arrhythmogenic Ca2+ waves and sarcoplasmic reticulum content-corrected Ca2+ sparks were less frequent in Gq-KO mice. Interestingly, nuclear but not cytosolic Ca2+ transient amplitudes were significantly decreased in Gq-KO mice. CONCLUSION Gq-signaling promotes arrhythmogenic atrial Ca2+-release and AF in mice. Targeting this pathway, ideally using Gq-selective, biased receptor ligands, may be a promising approach for the treatment and prevention of AF. Importantly, the atrial-specific expression of the Gq-effector IP3R confers atrial selectivity mitigating the risk of life-threatening ventricular pro-arrhythmic effects.
Collapse
Affiliation(s)
- Felix Hohendanner
- Department of Cardiology and German Heart Center, Campus Virchow-Klinikum, Charité–University Medicine Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), Partner Site Berlin, 13316 Berlin, Germany
- Berlin Institute of Health at Charité–Universitätsmedizin Berlin, 10117 Berlin, Germany
| | - Ashok Prabhu
- Department of Cardiology and German Heart Center, Campus Virchow-Klinikum, Charité–University Medicine Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Nicola Wilck
- DZHK (German Centre for Cardiovascular Research), Partner Site Berlin, 13316 Berlin, Germany
- Berlin Institute of Health at Charité–Universitätsmedizin Berlin, 10117 Berlin, Germany
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), 13125 Berlin, Germany
- Experimental and Clinical Research Center (ECRC), a Cooperation of Charité–Universitätsmedizin Berlin and Max Delbruck Center for Molecular Medicine (MDC), 13125 Berlin, Germany
- Department of Nephrology and Medical Intensive Care Medicine, Charité–Universitätsmedizin Berlin, 10117 Berlin, Germany
| | - Verena Stangl
- DZHK (German Centre for Cardiovascular Research), Partner Site Berlin, 13316 Berlin, Germany
- Berlin Institute of Health at Charité–Universitätsmedizin Berlin, 10117 Berlin, Germany
- Department of Cardiology and Angiology, Charité Campus Mitte, Charité–University Medicine Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Burkert Pieske
- Department of Cardiology and German Heart Center, Campus Virchow-Klinikum, Charité–University Medicine Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), Partner Site Berlin, 13316 Berlin, Germany
- Berlin Institute of Health at Charité–Universitätsmedizin Berlin, 10117 Berlin, Germany
| | - Karl Stangl
- DZHK (German Centre for Cardiovascular Research), Partner Site Berlin, 13316 Berlin, Germany
- Berlin Institute of Health at Charité–Universitätsmedizin Berlin, 10117 Berlin, Germany
- Department of Cardiology and Angiology, Charité Campus Mitte, Charité–University Medicine Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Till F. Althoff
- DZHK (German Centre for Cardiovascular Research), Partner Site Berlin, 13316 Berlin, Germany
- Berlin Institute of Health at Charité–Universitätsmedizin Berlin, 10117 Berlin, Germany
- Department of Cardiology and Angiology, Charité Campus Mitte, Charité–University Medicine Berlin, Charitéplatz 1, 10117 Berlin, Germany
- Arrhythmia Section, Cardiovascular Institute (ICCV), Hospital Clínic, Universitat de Barcelona, C/Villarroel N° 170, 08036 Barcelona, Spain
- Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036 Barcelona, Spain
- Correspondence: ; Tel.: +34-93-2275551; Fax: +34-93-4513045
| |
Collapse
|
6
|
Banach K, Blatter LA. The 'Reverse FDUF' Mechanism of Atrial Excitation-Contraction Coupling Sustains Calcium Alternans-A Hypothesis. Biomolecules 2022; 13:biom13010007. [PMID: 36671392 PMCID: PMC9855423 DOI: 10.3390/biom13010007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 12/07/2022] [Accepted: 12/15/2022] [Indexed: 12/24/2022] Open
Abstract
Cardiac calcium alternans is defined as beat-to-beat alternations of Ca transient (CaT) amplitude and has been linked to cardiac arrhythmia, including atrial fibrillation. We investigated the mechanism of atrial alternans in isolated rabbit atrial myocytes using high-resolution line scan confocal Ca imaging. Alternans was induced by increasing the pacing frequency until stable alternans was observed (1.6-2.5 Hz at room temperature). In atrial myocytes, action potential-induced Ca release is initiated in the cell periphery and subsequently propagates towards the cell center by Ca-induced Ca release (CICR) in a Ca wave-like fashion, driven by the newly identified 'fire-diffuse-uptake-fire' (FDUF) mechanism. The development of CaT alternans was accompanied by characteristic changes of the spatio-temporal organization of the CaT. During the later phase of the CaT, central [Ca]i exceeded peripheral [Ca]i that was indicative of a reversal of the subcellular [Ca]i gradient from centripetal to centrifugal. This gradient reversal resulted in a reversal of CICR propagation, causing a secondary Ca release during the large-amplitude alternans CaT, thereby prolonging the CaT, enhancing Ca-release refractoriness and reducing Ca release on the subsequent beat, thus enhancing the degree of CaT alternans. Here, we propose the 'reverse FDUF' mechanism as a novel cellular mechanism of atrial CaT alternans, which explains how the uncoupling of central from peripheral Ca release leads to the reversal of propagating CICR and to alternans.
Collapse
Affiliation(s)
- Kathrin Banach
- Department of Internal Medicine/Cardiology, Rush University Medical Center, Chicago, IL 60612, USA
| | - Lothar A. Blatter
- Department of Physiology & Biophysics, Rush University Medical Center, Chicago, IL 60612, USA
- Correspondence:
| |
Collapse
|
7
|
Demydenko K, Ekhteraei-Tousi S, Roderick HL. Inositol 1,4,5-trisphosphate receptors in cardiomyocyte physiology and disease. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210319. [PMID: 36189803 PMCID: PMC9527928 DOI: 10.1098/rstb.2021.0319] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The contraction of cardiac muscle underlying the pumping action of the heart is mediated by the process of excitation-contraction coupling (ECC). While triggered by Ca2+ entry across the sarcolemma during the action potential, it is the release of Ca2+ from the sarcoplasmic reticulum (SR) intracellular Ca2+ store via ryanodine receptors (RyRs) that plays the major role in induction of contraction. Ca2+ also acts as a key intracellular messenger regulating transcription underlying hypertrophic growth. Although Ca2+ release via RyRs is by far the greatest contributor to the generation of Ca2+ transients in the cardiomyocyte, Ca2+ is also released from the SR via inositol 1,4,5-trisphosphate (InsP3) receptors (InsP3Rs). This InsP3-induced Ca2+ release modifies Ca2+ transients during ECC, participates in directing Ca2+ to the mitochondria, and stimulates the transcription of genes underlying hypertrophic growth. Central to these specific actions of InsP3Rs is their localization to responsible signalling microdomains, the dyad, the SR-mitochondrial interface and the nucleus. In this review, the various roles of InsP3R in cardiac (patho)physiology and the mechanisms by which InsP3 signalling selectively influences the different cardiomyocyte cell processes in which it is involved will be presented. This article is part of the theme issue ‘The cardiomyocyte: new revelations on the interplay between architecture and function in growth, health, and disease’.
Collapse
Affiliation(s)
- Kateryna Demydenko
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium
| | - Samaneh Ekhteraei-Tousi
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium
| | - H Llewelyn Roderick
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium
| |
Collapse
|
8
|
Voglhuber J, Holzer M, Radulović S, Thai PN, Djalinac N, Matzer I, Wallner M, Bugger H, Zirlik A, Leitinger G, Dedkova EN, Bers DM, Ljubojevic-Holzer S. Functional remodelling of perinuclear mitochondria alters nucleoplasmic Ca 2+ signalling in heart failure. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210320. [PMID: 36189813 PMCID: PMC9527904 DOI: 10.1098/rstb.2021.0320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Accepted: 01/23/2022] [Indexed: 11/12/2022] Open
Abstract
Mitochondrial dysfunction in cardiomyocytes is a hallmark of heart failure development. Although initial studies recognized the importance of different mitochondrial subpopulations, there is a striking lack of direct comparison of intrafibrillar (IF) versus perinuclear (PN) mitochondria during the development of HF. Here, we use multiple approaches to examine the morphology and functional properties of IF versus PN mitochondria in pressure overload-induced cardiac remodelling in mice, and in non-failing and failing human cardiomyocytes. We demonstrate that PN mitochondria from failing cardiomyocytes are more susceptible to depolarization of mitochondrial membrane potential, reactive oxygen species generation and impairment in Ca2+ uptake compared with IF mitochondria at baseline and under physiological stress protocol. We also demonstrate, for the first time to our knowledge, that under normal conditions PN mitochondrial Ca2+ uptake shapes nucleoplasmic Ca2+ transients (CaTs) and limits nucleoplasmic Ca2+ loading. The loss of PN mitochondrial Ca2+ buffering capacity translates into increased nucleoplasmic CaTs and may explain disproportionate rise in nucleoplasmic [Ca2+] in failing cardiomyocytes at increased stimulation frequencies. Therefore, a previously unidentified benefit of restoring the mitochondrial Ca2+ uptake may be normalization of nuclear Ca2+ signalling and alleviation of altered excitation-transcription, which could be an important therapeutic approach to prevent adverse cardiac remodelling. This article is part of the theme issue 'The cardiomyocyte: new revelations on the interplay between architecture and function in growth, health, and disease'.
Collapse
Affiliation(s)
- Julia Voglhuber
- Department of Cardiology, Medical University of Graz, Graz, Austria
- BioTechMed-Graz, Graz, Austria
| | - Michael Holzer
- BioTechMed-Graz, Graz, Austria
- Division of Pharmacology, Otto-Loewi Research Centre, Medical University of Graz, Graz, Austria
| | - Snježana Radulović
- Research Unit Electron Microscopic Techniques, Division of Cell Biology, Histology and Embryology, Gottfried Schatz Research Center, Medical University of Graz, Graz, Austria
| | - Phung N. Thai
- Department of Internal Medicine, Cardiovascular Medicine, University of California Davis, Davis, CA, USA
| | - Natasa Djalinac
- Department of Cardiology, Medical University of Graz, Graz, Austria
| | - Ingrid Matzer
- Department of Cardiology, Medical University of Graz, Graz, Austria
| | - Markus Wallner
- Department of Cardiology, Medical University of Graz, Graz, Austria
- Lewis Katz School of Medicine, Temple University, Cardiovascular Research Center, Philadelphia, PA, USA
| | - Heiko Bugger
- Department of Cardiology, Medical University of Graz, Graz, Austria
| | - Andreas Zirlik
- Department of Cardiology, Medical University of Graz, Graz, Austria
| | - Gerd Leitinger
- Research Unit Electron Microscopic Techniques, Division of Cell Biology, Histology and Embryology, Gottfried Schatz Research Center, Medical University of Graz, Graz, Austria
| | - Elena N. Dedkova
- Department of Pharmacology, University of California Davis, Davis, CA, USA
- Department of Molecular Biosciences, University of California Davis, Davis, CA, USA
| | - Donald M. Bers
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - Senka Ljubojevic-Holzer
- Department of Cardiology, Medical University of Graz, Graz, Austria
- BioTechMed-Graz, Graz, Austria
- Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, Graz, Austria
| |
Collapse
|
9
|
Bode D, Semmler L, Wakula P, Hegemann N, Primessnig U, Beindorff N, Powell D, Dahmen R, Ruetten H, Oeing C, Alogna A, Messroghli D, Pieske BM, Heinzel FR, Hohendanner F. Dual SGLT-1 and SGLT-2 inhibition improves left atrial dysfunction in HFpEF. Cardiovasc Diabetol 2021; 20:7. [PMID: 33413413 PMCID: PMC7792219 DOI: 10.1186/s12933-020-01208-z] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 12/27/2020] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Sodium-glucose linked transporter type 2 (SGLT-2) inhibition has been shown to reduce cardiovascular mortality in heart failure independently of glycemic control and prevents the onset of atrial arrhythmias, a common co-morbidity in heart failure with preserved ejection fraction (HFpEF). The mechanism behind these effects is not fully understood, and it remains unclear if they could be further enhanced by additional SGLT-1 inhibition. We investigated the effects of chronic treatment with the dual SGLT-1&2 inhibitor sotagliflozin on left atrial (LA) remodeling and cellular arrhythmogenesis (i.e. atrial cardiomyopathy) in a metabolic syndrome-related rat model of HFpEF. METHODS 17 week-old ZSF-1 obese rats, a metabolic syndrome-related model of HFpEF, and wild type rats (Wistar Kyoto), were fed 30 mg/kg/d sotagliflozin for 6 weeks. At 23 weeks, LA were imaged in-vivo by echocardiography. In-vitro, Ca2+ transients (CaT; electrically stimulated, caffeine-induced) and spontaneous Ca2+ release were recorded by ratiometric microscopy using Ca2+-sensitive fluorescent dyes (Fura-2) during various experimental protocols. Mitochondrial structure (dye: Mitotracker), Ca2+ buffer capacity (dye: Rhod-2), mitochondrial depolarization (dye: TMRE) and production of reactive oxygen species (dye: H2DCF) were visualized by confocal microscopy. Statistical analysis was performed with 2-way analysis of variance followed by post-hoc Bonferroni and student's t-test, as applicable. RESULTS Sotagliflozin ameliorated LA enlargement in HFpEF in-vivo. In-vitro, LA cardiomyocytes in HFpEF showed an increased incidence and amplitude of arrhythmic spontaneous Ca2+ release events (SCaEs). Sotagliflozin significantly reduced the magnitude of SCaEs, while their frequency was unaffected. Sotagliflozin lowered diastolic [Ca2+] of CaT at baseline and in response to glucose influx, possibly related to a ~ 50% increase of sodium sodium-calcium exchanger (NCX) forward-mode activity. Sotagliflozin prevented mitochondrial swelling and enhanced mitochondrial Ca2+ buffer capacity in HFpEF. Sotagliflozin improved mitochondrial fission and reactive oxygen species (ROS) production during glucose starvation and averted Ca2+ accumulation upon glycolytic inhibition. CONCLUSION The SGLT-1&2 inhibitor sotagliflozin ameliorated LA remodeling in metabolic HFpEF. It also improved distinct features of Ca2+-mediated cellular arrhythmogenesis in-vitro (i.e. magnitude of SCaEs, mitochondrial Ca2+ buffer capacity, diastolic Ca2+ accumulation, NCX activity). The safety and efficacy of combined SGLT-1&2 inhibition for the treatment and/or prevention of atrial cardiomyopathy associated arrhythmias should be further evaluated in clinical trials.
Collapse
MESH Headings
- Animals
- Arrhythmias, Cardiac/etiology
- Arrhythmias, Cardiac/metabolism
- Arrhythmias, Cardiac/physiopathology
- Arrhythmias, Cardiac/prevention & control
- Atrial Function, Left/drug effects
- Atrial Remodeling/drug effects
- Calcium Signaling/drug effects
- Disease Models, Animal
- Glycosides/pharmacology
- Heart Atria/drug effects
- Heart Atria/metabolism
- Heart Atria/physiopathology
- Heart Failure/drug therapy
- Heart Failure/etiology
- Heart Failure/metabolism
- Heart Failure/physiopathology
- Metabolic Syndrome/complications
- Mitochondria, Heart/drug effects
- Mitochondria, Heart/metabolism
- Mitochondria, Heart/pathology
- Mitochondrial Dynamics/drug effects
- Mitochondrial Swelling/drug effects
- Rats, Inbred WKY
- Rats, Zucker
- Reactive Oxygen Species/metabolism
- Sodium-Calcium Exchanger/metabolism
- Sodium-Glucose Transporter 1/antagonists & inhibitors
- Sodium-Glucose Transporter 1/metabolism
- Sodium-Glucose Transporter 2/metabolism
- Sodium-Glucose Transporter 2 Inhibitors/pharmacology
- Rats
Collapse
Affiliation(s)
- David Bode
- Department of Internal Medicine and Cardiology, Charité University Medicine, Campus Virchow-Klinikum, Augustenburgerplatz 1, 13353, Berlin, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Berlin, Berlin, Germany
- Berlin Institute of Health (BIH), Berlin, Germany
| | - Lukas Semmler
- Department of Internal Medicine and Cardiology, Charité University Medicine, Campus Virchow-Klinikum, Augustenburgerplatz 1, 13353, Berlin, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Berlin, Berlin, Germany
| | - Paulina Wakula
- Department of Internal Medicine and Cardiology, Charité University Medicine, Campus Virchow-Klinikum, Augustenburgerplatz 1, 13353, Berlin, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Berlin, Berlin, Germany
| | - Niklas Hegemann
- Department of Internal Medicine and Cardiology, Charité University Medicine, Campus Virchow-Klinikum, Augustenburgerplatz 1, 13353, Berlin, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Berlin, Berlin, Germany
| | - Uwe Primessnig
- Department of Internal Medicine and Cardiology, Charité University Medicine, Campus Virchow-Klinikum, Augustenburgerplatz 1, 13353, Berlin, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Berlin, Berlin, Germany
- Berlin Institute of Health (BIH), Berlin, Germany
| | - Nicola Beindorff
- Berlin Experimental Radionuclide Imaging Center (BERIC), Charité-Universitaetsmedizin Berlin, Berlin, Germany
| | - David Powell
- Lexicon Pharmaceuticals, Metabolism Research, Houston, TX, USA
| | - Raphael Dahmen
- Sanofi-Aventis Deutschland GmbH, Research & Development, 65926, Frankfurt am Main, Germany
| | - Hartmut Ruetten
- Sanofi-Aventis Deutschland GmbH, Research & Development, 65926, Frankfurt am Main, Germany
| | - Christian Oeing
- Department of Internal Medicine and Cardiology, Charité University Medicine, Campus Virchow-Klinikum, Augustenburgerplatz 1, 13353, Berlin, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Berlin, Berlin, Germany
- Berlin Institute of Health (BIH), Berlin, Germany
| | - Alessio Alogna
- Department of Internal Medicine and Cardiology, Charité University Medicine, Campus Virchow-Klinikum, Augustenburgerplatz 1, 13353, Berlin, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Berlin, Berlin, Germany
- Berlin Institute of Health (BIH), Berlin, Germany
| | - Daniel Messroghli
- Department of Internal Medicine and Cardiology, Charité University Medicine, Campus Virchow-Klinikum, Augustenburgerplatz 1, 13353, Berlin, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Berlin, Berlin, Germany
- Department of Internal Medicine and Cardiology, German Heart Center Berlin, 13353, Berlin, Germany
| | - Burkert M Pieske
- Department of Internal Medicine and Cardiology, Charité University Medicine, Campus Virchow-Klinikum, Augustenburgerplatz 1, 13353, Berlin, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Berlin, Berlin, Germany
- Department of Internal Medicine and Cardiology, German Heart Center Berlin, 13353, Berlin, Germany
| | - Frank R Heinzel
- Department of Internal Medicine and Cardiology, Charité University Medicine, Campus Virchow-Klinikum, Augustenburgerplatz 1, 13353, Berlin, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Berlin, Berlin, Germany
| | - Felix Hohendanner
- Department of Internal Medicine and Cardiology, Charité University Medicine, Campus Virchow-Klinikum, Augustenburgerplatz 1, 13353, Berlin, Germany.
- German Center for Cardiovascular Research (DZHK), Partner Site Berlin, Berlin, Germany.
- Berlin Institute of Health (BIH), Berlin, Germany.
| |
Collapse
|
10
|
Blatter LA, Kanaporis G, Martinez-Hernandez E, Oropeza-Almazan Y, Banach K. Excitation-contraction coupling and calcium release in atrial muscle. Pflugers Arch 2021; 473:317-329. [PMID: 33398498 DOI: 10.1007/s00424-020-02506-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 12/03/2020] [Accepted: 12/16/2020] [Indexed: 01/02/2023]
Abstract
In cardiac muscle, the process of excitation-contraction coupling (ECC) describes the chain of events that links action potential induced myocyte membrane depolarization, surface membrane ion channel activation, triggering of Ca2+ induced Ca2+ release from the sarcoplasmic reticulum (SR) Ca2+ store to activation of the contractile machinery that is ultimately responsible for the pump function of the heart. Here we review similarities and differences of structural and functional attributes of ECC between atrial and ventricular tissue. We explore a novel "fire-diffuse-uptake-fire" paradigm of atrial ECC and Ca2+ release that assigns a novel role to the SR SERCA pump and involves a concerted "tandem" activation of the ryanodine receptor Ca2+ release channel by cytosolic and luminal Ca2+. We discuss the contribution of the inositol 1,4,5-trisphosphate (IP3) receptor Ca2+ release channel as an auxiliary pathway to Ca2+ signaling, and we review IP3 receptor-induced Ca2+ release involvement in beat-to-beat ECC, nuclear Ca2+ signaling, and arrhythmogenesis. Finally, we explore the topic of electromechanical and Ca2+ alternans and its ramifications for atrial arrhythmia.
Collapse
Affiliation(s)
- L A Blatter
- Department of Physiology & Biophysics, Rush University Medical Center, 1750 W. Harrison Street, Chicago, IL, 60612, USA.
| | - G Kanaporis
- Department of Physiology & Biophysics, Rush University Medical Center, 1750 W. Harrison Street, Chicago, IL, 60612, USA
| | - E Martinez-Hernandez
- Department of Physiology & Biophysics, Rush University Medical Center, 1750 W. Harrison Street, Chicago, IL, 60612, USA
| | - Y Oropeza-Almazan
- Department of Physiology & Biophysics, Rush University Medical Center, 1750 W. Harrison Street, Chicago, IL, 60612, USA
| | - K Banach
- Department of Internal Medicine/Cardiology, Rush University Medical Center, Chicago, IL, 60612, USA
| |
Collapse
|
11
|
Oropeza-Almazán Y, Blatter LA. Mitochondrial calcium uniporter complex activation protects against calcium alternans in atrial myocytes. Am J Physiol Heart Circ Physiol 2020; 319:H873-H881. [PMID: 32857593 DOI: 10.1152/ajpheart.00375.2020] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Cardiac alternans, defined as beat-to-beat alternations in action potential duration, cytosolic Ca transient (CaT) amplitude, and cardiac contraction is associated with atrial fibrillation (AF) and sudden cardiac death. At the cellular level, cardiac alternans is linked to abnormal intracellular calcium handling during excitation-contraction coupling. We investigated how pharmacological activation or inhibition of cytosolic Ca sequestration via mitochondrial Ca uptake and mitochondrial Ca retention affects the occurrence of pacing-induced CaT alternans in isolated rabbit atrial myocytes. Cytosolic CaTs were recorded using Fluo-4 fluorescence microscopy. Alternans was quantified as the alternans ratio (AR = 1 - CaTsmall/CaTlarge, where CaTsmall and CaTlarge are the amplitudes of the small and large CaTs of a pair of alternating CaTs). Inhibition of mitochondrial Ca sequestration via mitochondrial Ca uniporter complex (MCUC) with Ru360 enhanced the severity of CaT alternans (AR increase) and lowered the pacing frequency threshold for alternans. In contrast, stimulation of MCUC mediated mitochondrial Ca uptake with spermine-rescued alternans (AR decrease) and increased the alternans pacing threshold. Direct measurement of mitochondrial [Ca] in membrane permeabilized myocytes with Fluo-4 loaded mitochondria revealed that spermine enhanced and accelerated mitochondrial Ca uptake. Stimulation of mitochondrial Ca retention by preventing mitochondrial Ca efflux through the mitochondrial permeability transition pore with cyclosporin A also protected from alternans and increased the alternans pacing threshold. Pharmacological manipulation of MCUC activity did not affect sarcoplasmic reticulum Ca load. Our results suggest that activation of Ca sequestration by mitochondria protects from CaT alternans and could be a potential therapeutic target for cardiac alternans and AF prevention.NEW & NOTEWORTHY This study provides conclusive evidence that mitochondrial Ca uptake and retention protects from Ca alternans, whereas uptake inhibition enhances Ca alternans. The data suggest pharmacological mitochondrial Ca cycling modulation as a potential therapeutic strategy for alternans-related cardiac arrhythmia prevention.
Collapse
Affiliation(s)
| | - Lothar A Blatter
- Department of Physiology and Biophysics, Rush University Medical Center, Chicago, Illinois
| |
Collapse
|
12
|
Ljubojevic-Holzer S, Herren AW, Djalinac N, Voglhuber J, Morotti S, Holzer M, Wood BM, Abdellatif M, Matzer I, Sacherer M, Radulovic S, Wallner M, Ivanov M, Wagner S, Sossalla S, von Lewinski D, Pieske B, Brown JH, Sedej S, Bossuyt J, Bers DM. CaMKIIδC Drives Early Adaptive Ca 2+ Change and Late Eccentric Cardiac Hypertrophy. Circ Res 2020; 127:1159-1178. [PMID: 32821022 PMCID: PMC7547876 DOI: 10.1161/circresaha.120.316947] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Supplemental Digital Content is available in the text. CaMKII (Ca2+-Calmodulin dependent protein kinase) δC activation is implicated in pathological progression of heart failure (HF) and CaMKIIδC transgenic mice rapidly develop HF and arrhythmias. However, little is known about early spatio-temporal Ca2+ handling and CaMKII activation in hypertrophy and HF.
Collapse
Affiliation(s)
- Senka Ljubojevic-Holzer
- Department of Cardiology (S.L.-H., N.D., J.V., M.A., I.M., M.S., S.R., M.W., D.v.L., S. Sedej), Medical University of Graz, Austria.,Department of Pharmacology, University of California, Davis, CA (S.L.-H., A.W.H., S.M., B.M.W., J.B., D.M.B.).,BioTechMed Graz, Austria (S.L.-H., J.V., S. Sedej)
| | - Anthony W Herren
- Department of Pharmacology, University of California, Davis, CA (S.L.-H., A.W.H., S.M., B.M.W., J.B., D.M.B.)
| | - Natasa Djalinac
- Department of Cardiology (S.L.-H., N.D., J.V., M.A., I.M., M.S., S.R., M.W., D.v.L., S. Sedej), Medical University of Graz, Austria
| | - Julia Voglhuber
- Department of Cardiology (S.L.-H., N.D., J.V., M.A., I.M., M.S., S.R., M.W., D.v.L., S. Sedej), Medical University of Graz, Austria.,BioTechMed Graz, Austria (S.L.-H., J.V., S. Sedej)
| | - Stefano Morotti
- Department of Pharmacology, University of California, Davis, CA (S.L.-H., A.W.H., S.M., B.M.W., J.B., D.M.B.)
| | - Michael Holzer
- Otto-Loewi Research Centre, Division of Pharmacology (M.H.), Medical University of Graz, Austria
| | - Brent M Wood
- Department of Pharmacology, University of California, Davis, CA (S.L.-H., A.W.H., S.M., B.M.W., J.B., D.M.B.)
| | - Mahmoud Abdellatif
- Department of Cardiology (S.L.-H., N.D., J.V., M.A., I.M., M.S., S.R., M.W., D.v.L., S. Sedej), Medical University of Graz, Austria
| | - Ingrid Matzer
- Department of Cardiology (S.L.-H., N.D., J.V., M.A., I.M., M.S., S.R., M.W., D.v.L., S. Sedej), Medical University of Graz, Austria
| | - Michael Sacherer
- Department of Cardiology (S.L.-H., N.D., J.V., M.A., I.M., M.S., S.R., M.W., D.v.L., S. Sedej), Medical University of Graz, Austria
| | - Snjezana Radulovic
- Department of Cardiology (S.L.-H., N.D., J.V., M.A., I.M., M.S., S.R., M.W., D.v.L., S. Sedej), Medical University of Graz, Austria
| | - Markus Wallner
- Department of Cardiology (S.L.-H., N.D., J.V., M.A., I.M., M.S., S.R., M.W., D.v.L., S. Sedej), Medical University of Graz, Austria
| | - Milan Ivanov
- Institute for Medical Research, University of Belgrade, Serbia (M.I.)
| | - Stefan Wagner
- Klinik und Poliklinik für Innere Medizin II, Universitätsklinikum Regensburg, Germany (S.W., S. Sossalla)
| | - Samuel Sossalla
- Klinik für Kardiologie und Pneumologie, Georg-August-Universität Göttingen, Germany (S. Sossalla).,Klinik und Poliklinik für Innere Medizin II, Universitätsklinikum Regensburg, Germany (S.W., S. Sossalla)
| | - Dirk von Lewinski
- Department of Cardiology (S.L.-H., N.D., J.V., M.A., I.M., M.S., S.R., M.W., D.v.L., S. Sedej), Medical University of Graz, Austria
| | - Burkert Pieske
- Department of Internal Medicine and Cardiology, Charité University Medicine Berlin, Germany (B.P.)
| | - Joan Heller Brown
- Department of Pharmacology, University of California San Diego, La Jolla (J.H.B.)
| | - Simon Sedej
- Department of Cardiology (S.L.-H., N.D., J.V., M.A., I.M., M.S., S.R., M.W., D.v.L., S. Sedej), Medical University of Graz, Austria.,BioTechMed Graz, Austria (S.L.-H., J.V., S. Sedej).,Faculty of Medicine, Institute of Physiology, University of Maribor, Slovenia (S. Sedej)
| | - Julie Bossuyt
- Department of Pharmacology, University of California, Davis, CA (S.L.-H., A.W.H., S.M., B.M.W., J.B., D.M.B.)
| | - Donald M Bers
- Department of Pharmacology, University of California, Davis, CA (S.L.-H., A.W.H., S.M., B.M.W., J.B., D.M.B.)
| |
Collapse
|
13
|
Ca 2+ Release via IP 3 Receptors Shapes the Cardiac Ca 2+ Transient for Hypertrophic Signaling. Biophys J 2020; 119:1178-1192. [PMID: 32871099 DOI: 10.1016/j.bpj.2020.08.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 06/16/2020] [Accepted: 08/04/2020] [Indexed: 12/27/2022] Open
Abstract
Calcium (Ca2+) plays a central role in mediating both contractile function and hypertrophic signaling in ventricular cardiomyocytes. L-type Ca2+ channels trigger release of Ca2+ from ryanodine receptors for cellular contraction, whereas signaling downstream of G-protein-coupled receptors stimulates Ca2+ release via inositol 1,4,5-trisphosphate receptors (IP3Rs), engaging hypertrophic signaling pathways. Modulation of the amplitude, duration, and duty cycle of the cytosolic Ca2+ contraction signal and spatial localization have all been proposed to encode this hypertrophic signal. Given current knowledge of IP3Rs, we develop a model describing the effect of functional interaction (cross talk) between ryanodine receptor and IP3R channels on the Ca2+ transient and examine the sensitivity of the Ca2+ transient shape to properties of IP3R activation. A key result of our study is that IP3R activation increases Ca2+ transient duration for a broad range of IP3R properties, but the effect of IP3R activation on Ca2+ transient amplitude is dependent on IP3 concentration. Furthermore we demonstrate that IP3-mediated Ca2+ release in the cytosol increases the duty cycle of the Ca2+ transient, the fraction of the cycle for which [Ca2+] is elevated, across a broad range of parameter values and IP3 concentrations. When coupled to a model of downstream transcription factor (NFAT) activation, we demonstrate that there is a high correspondence between the Ca2+ transient duty cycle and the proportion of activated NFAT in the nucleus. These findings suggest increased cytosolic Ca2+ duty cycle as a plausible mechanism for IP3-dependent hypertrophic signaling via Ca2+-sensitive transcription factors such as NFAT in ventricular cardiomyocytes.
Collapse
|
14
|
Inositol 1,4,5-Trisphosphate Receptors in Human Disease: A Comprehensive Update. J Clin Med 2020; 9:jcm9041096. [PMID: 32290556 PMCID: PMC7231134 DOI: 10.3390/jcm9041096] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 03/30/2020] [Accepted: 04/10/2020] [Indexed: 12/22/2022] Open
Abstract
Inositol 1,4,5-trisphosphate receptors (ITPRs) are intracellular calcium release channels located on the endoplasmic reticulum of virtually every cell. Herein, we are reporting an updated systematic summary of the current knowledge on the functional role of ITPRs in human disorders. Specifically, we are describing the involvement of its loss-of-function and gain-of-function mutations in the pathogenesis of neurological, immunological, cardiovascular, and neoplastic human disease. Recent results from genome-wide association studies are also discussed.
Collapse
|
15
|
Kirschner Peretz N, Segal S, Yaniv Y. May the Force Not Be With You During Culture: Eliminating Mechano-Associated Feedback During Culture Preserves Cultured Atrial and Pacemaker Cell Functions. Front Physiol 2020; 11:163. [PMID: 32265724 PMCID: PMC7100534 DOI: 10.3389/fphys.2020.00163] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Accepted: 02/12/2020] [Indexed: 01/24/2023] Open
Abstract
Cultured cardiomyocytes have been shown to possess significant potential as a model for characterization of mechano-Ca2+, mechano-electric, and mechano-metabolic feedbacks in the heart. However, the majority of cultured cardiomyocytes exhibit impaired electrical, mechanical, biochemical, and metabolic functions. More specifically, the cells do not beat spontaneously (pacemaker cells) or beat at a rate far lower than their physiological counterparts and self-oscillate (atrial and ventricular cells) in culture. Thus, efforts are being invested in ensuring that cultured cardiomyocytes maintain the shape and function of freshly isolated cells. Elimination of contraction during culture has been shown to preserve the mechano-Ca2+, mechano-electric, and mechano-metabolic feedback loops of cultured cells. This review focuses on pacemaker cells, which reside in the sinoatrial node (SAN) and generate regular heartbeat through the initiation of the heart’s electrical, metabolic, and biochemical activities. In parallel, it places emphasis on atrial cells, which are responsible for bridging the electrical conductance from the SAN to the ventricle. The review provides a summary of the main mechanisms responsible for mechano-electrical, Ca2+, and metabolic feedback in pacemaker and atrial cells and of culture methods existing for both cell types. The work concludes with an explanation of how the elimination of mechano-electrical, mechano-Ca2+, and mechano-metabolic feedbacks during culture results in sustained cultured cell function.
Collapse
Affiliation(s)
- Noa Kirschner Peretz
- Biomedical Engineering Faculty, Technion Israel Institute of Technology, Haifa, Israel
| | - Sofia Segal
- Biomedical Engineering Faculty, Technion Israel Institute of Technology, Haifa, Israel
| | - Yael Yaniv
- Biomedical Engineering Faculty, Technion Israel Institute of Technology, Haifa, Israel
| |
Collapse
|
16
|
Gilbert G, Demydenko K, Dries E, Puertas RD, Jin X, Sipido K, Roderick HL. Calcium Signaling in Cardiomyocyte Function. Cold Spring Harb Perspect Biol 2020; 12:cshperspect.a035428. [PMID: 31308143 DOI: 10.1101/cshperspect.a035428] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Rhythmic increases in intracellular Ca2+ concentration underlie the contractile function of the heart. These heart muscle-wide changes in intracellular Ca2+ are induced and coordinated by electrical depolarization of the cardiomyocyte sarcolemma by the action potential. Originating at the sinoatrial node, conduction of this electrical signal throughout the heart ensures synchronization of individual myocytes into an effective cardiac pump. Ca2+ signaling pathways also regulate gene expression and cardiomyocyte growth during development and in pathology. These fundamental roles of Ca2+ in the heart are illustrated by the prevalence of altered Ca2+ homeostasis in cardiovascular diseases. Indeed, heart failure (an inability of the heart to support hemodynamic needs), rhythmic disturbances, and inappropriate cardiac growth all share an involvement of altered Ca2+ handling. The prevalence of these pathologies, contributing to a third of all deaths in the developed world as well as to substantial morbidity makes understanding the mechanisms of Ca2+ handling and dysregulation in cardiomyocytes of great importance.
Collapse
Affiliation(s)
- Guillaume Gilbert
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, BE3000 Leuven, Belgium
| | - Kateryna Demydenko
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, BE3000 Leuven, Belgium
| | - Eef Dries
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, BE3000 Leuven, Belgium
| | - Rosa Doñate Puertas
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, BE3000 Leuven, Belgium
| | - Xin Jin
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, BE3000 Leuven, Belgium
| | - Karin Sipido
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, BE3000 Leuven, Belgium
| | - H Llewelyn Roderick
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, BE3000 Leuven, Belgium
| |
Collapse
|
17
|
Abstract
The aim of this chapter is to discuss evidence concerning the many roles of calcium ions, Ca2+, in cell signaling pathways that control heart function. Before considering details of these signaling pathways, the control of contraction in ventricular muscle by Ca2+ transients accompanying cardiac action potentials is first summarized, together with a discussion of how myocytes from the atrial and pacemaker regions of the heart diverge from this basic scheme. Cell signaling pathways regulate the size and timing of the Ca2+ transients in the different heart regions to influence function. The simplest Ca2+ signaling elements involve enzymes that are regulated by cytosolic Ca2+. Particularly important examples to be discussed are those that are stimulated by Ca2+, including Ca2+-calmodulin-dependent kinase (CaMKII), Ca2+ stimulated adenylyl cyclases, Ca2+ stimulated phosphatase and NO synthases. Another major aspect of Ca2+ signaling in the heart concerns actions of the Ca2+ mobilizing agents, inositol trisphosphate (IP3), cADP-ribose (cADPR) and nicotinic acid adenine dinucleotide phosphate, (NAADP). Evidence concerning roles of these Ca2+ mobilizing agents in different regions of the heart is discussed in detail. The focus of the review will be on short term regulation of Ca2+ transients and contractile function, although it is recognized that Ca2+ regulation of gene expression has important long term functional consequences which will also be briefly discussed.
Collapse
|
18
|
Lu X, Thai PN, Lu S, Pu J, Bers DM. Intrafibrillar and perinuclear mitochondrial heterogeneity in adult cardiac myocytes. J Mol Cell Cardiol 2019; 136:72-84. [PMID: 31491377 DOI: 10.1016/j.yjmcc.2019.08.013] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Revised: 08/12/2019] [Accepted: 08/28/2019] [Indexed: 12/20/2022]
Abstract
Mitochondria are involved in multiple cellular functions, in addition to their core role in energy metabolism. Mitochondria localized in different cellular locations may have different morphology, Ca2+ handling and biochemical properties and may interact differently with other intracellular structures, causing functional specificity. However, most prior studies have utilized isolated mitochondria, removed from their intracellular environment. Mitochondria in cardiac ventricular myocytes are highly organized, with a majority squeezed between the myofilaments in longitudinal chains (intrafibrillar mitochondria, IFM). There is another population of perinuclear mitochondria (PNM) around and between the two nuclei typical in myocytes. Here, we take advantage of live myocyte imaging to test for quantitative morphological and functional differences between IFM and PNM with respect to calcium fluxes, membrane potential, sensitivity to oxidative stress, shape and dynamics. Our findings show higher mitochondrial Ca2+ uptake and oxidative stress sensitivity for IFM vs. PNM, which may relate to higher local energy demand supporting the contractile machinery. In contrast to IFM which are remarkably static, PNM are relatively mobile, appear to participate readily in fission/fusion dynamics and appear to play a central role in mitochondrial genesis and turnover. We conclude that while IFM may be physiologically tuned to support local myofilament energy demands, PNM may be more critical in mitochondrial turnover and regulation of nuclear function and import/export. Thus, important functional differences are present in intrafibrillar vs. perinuclear mitochondrial subpopulations.
Collapse
Affiliation(s)
- Xiyuan Lu
- Division of Cardiology, State Key Laboratory for Oncogenes and Related Genes, Renji Hospital School of Medicine, Shanghai Cancer Institute, Jiaotong University, Shanghai, China; Department of Pharmacology, University of California Davis, Davis, CA, USA.
| | - Phung N Thai
- Department of Internal Medicine, University of California Davis, Davis, CA, USA
| | - Shan Lu
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - Jun Pu
- Division of Cardiology, State Key Laboratory for Oncogenes and Related Genes, Renji Hospital School of Medicine, Shanghai Cancer Institute, Jiaotong University, Shanghai, China
| | - Donald M Bers
- Department of Pharmacology, University of California Davis, Davis, CA, USA.
| |
Collapse
|
19
|
Mhatre KN, Wakula P, Klein O, Bisping E, Völkl J, Pieske B, Heinzel FR. Crosstalk between FGF23- and angiotensin II-mediated Ca 2+ signaling in pathological cardiac hypertrophy. Cell Mol Life Sci 2018; 75:4403-4416. [PMID: 30062428 PMCID: PMC11105615 DOI: 10.1007/s00018-018-2885-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Revised: 07/16/2018] [Accepted: 07/19/2018] [Indexed: 02/07/2023]
Abstract
Heart failure (HF) manifestation and progression are driven by systemic activation of neuroendocrine signaling cascades, such as the renin-angiotensin aldosterone system (RAAS). Fibroblast growth factor 23 (FGF23), an endocrine hormone, is linked to HF and cardiovascular mortality. It is also a mediator of left-ventricular hypertrophy (LVH). In vivo, high circulating levels of FGF23 are associated with an altered systemic RAAS response. FGF23 is proposed to trigger pathological signaling mediated by Ca2+-regulated transcriptional pathways. In the present study, we investigated Ca2+-dependent signaling of FGF23 in ventricular cardiomyocytes and its association with angiotensin II (ATII). In neonatal rat ventricular myocytes (NRVMs), both ATII and FGF23 induced hypertrophy as observed by an increase in cell area and hypertrophic gene expression. Furthermore, FGF23 activates nuclear Ca2+-regulated CaMKII-HDAC4 pathway, similar to ATII. In addition to a global increase in cytoplasmic Ca2+, FGF23, like ATII, induced inositol 1, 4, 5-triphosphate (IP3)-induced Ca2+ release from the nucleoplasmic Ca2+ store, associated with cellular hypertrophy. Interestingly, ATII receptor antagonist, losartan, significantly attenuated FGF23-induced changes in Ca2+ homeostasis and cellular hypertrophy suggesting an involvement of ATII receptor-mediated signaling. In addition, application of FGF23 increased intracellular expression of ATII peptide and its secretion in NRVMs, confirming the participation of ATII. In conclusion, FGF23 and ATII share a common mechanism of IP3-nuclear Ca2+-dependent cardiomyocyte hypertrophy. FGF23-mediated cellular hypertrophy is associated with increased production and secretion of ATII by cardiomyocytes. These findings indicate a pathophysiological role of the cellular angiotensin system in FGF23-induced hypertrophy in ventricular cardiomyocytes.
Collapse
Affiliation(s)
- Ketaki N Mhatre
- Department of Internal Medicine and Cardiology, Charité University Medicine, Campus Virchow-Klinikum, 13353, Berlin, Germany
- Department of Cardiology, Medical University Graz, Auenbruggerplatz 15, 8036, Graz, Austria
| | - Paulina Wakula
- Department of Internal Medicine and Cardiology, Charité University Medicine, Campus Virchow-Klinikum, 13353, Berlin, Germany
| | - Oliver Klein
- Department of Internal Medicine and Cardiology, Charité University Medicine, Campus Virchow-Klinikum, 13353, Berlin, Germany
| | - Egbert Bisping
- Department of Cardiology, Medical University Graz, Auenbruggerplatz 15, 8036, Graz, Austria
| | - Jakob Völkl
- Department of Internal Medicine and Cardiology, Charité University Medicine, Campus Virchow-Klinikum, 13353, Berlin, Germany
| | - Burkert Pieske
- Department of Internal Medicine and Cardiology, Charité University Medicine, Campus Virchow-Klinikum, 13353, Berlin, Germany
- German Center for Cardiovascular Research (DZHK), Berlin, Germany
- Department of Internal Medicine and Cardiology, German Heart Center, 13353, Berlin, Germany
| | - Frank R Heinzel
- Department of Internal Medicine and Cardiology, Charité University Medicine, Campus Virchow-Klinikum, 13353, Berlin, Germany.
- German Center for Cardiovascular Research (DZHK), Berlin, Germany.
| |
Collapse
|
20
|
Cellular mechanisms of metabolic syndrome-related atrial decompensation in a rat model of HFpEF. J Mol Cell Cardiol 2017; 115:10-19. [PMID: 29289652 DOI: 10.1016/j.yjmcc.2017.12.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Revised: 11/30/2017] [Accepted: 12/27/2017] [Indexed: 11/23/2022]
Abstract
Heart failure (HF) with preserved ejection fraction (HFpEF) is present in about 50% of HF patients. Atrial remodeling is common in HFpEF and associated with increased mortality. We postulate that atrial remodeling is associated with atrial dysfunction in vivo related to alterations in cardiomyocyte Calcium (Ca) signaling and remodeling. We examined atrial function in vivo and Ca transients (CaT) (Fluo4-AM, field stim) in atrial cardiomyocytes of ZSF-1 rats without (Ln; lean hypertensive) and with metabolic syndrome (Ob; obese, hypertensive, diabetic) and HFpEF. RESULTS At 21weeks Ln showed an increased left ventricular (LV) mass and left ventricular end-diastolic pressure (LVEDP), but unchanged left atrial (LA) size and preserved atrial ejection fraction vs. wild-type (WT). CaT amplitude in atrial cardiomyocytes was increased in Ln (2.9±0.2 vs. 2.3±0.2F/F0 in WT; n=22 cells/group; p<0.05). Studying subcellular Ca release in more detail, we found that local central cytosolic CaT amplitude was increased, while subsarcolemmal CaT amplitudes remained unchanged. Moreover, Sarcoplasmic reticulum (SR) Ca content (caffeine) was preserved while Ca spark frequency and tetracaine-dependent SR Ca leak were significantly increased in Ln. Ob mice developed a HFpEF phenotype in vivo, LA area was significantly increased and atrial in vivo function was impaired, despite increased atrial CaT amplitudes in vitro (2.8±0.2; p<0.05 vs. WT). Ob cells showed alterations of the tubular network possibly contributing to the observed phenotype. CaT kinetics as well as SR Ca in Ob were not significantly different from WT, but SR Ca leak remained increased. Angiotensin II (Ang II) reduced in vitro cytosolic CaT amplitudes and let to active nuclear Ca release in Ob but not in Ln or WT. SUMMARY In hypertensive ZSF-1 rats, a possibly compensatory increase of cytosolic CaT amplitude and increased SR Ca leak precede atrial remodeling and HFpEF. Atrial remodeling in ZSF-1 HFpEF is associated with an altered tubular network in-vitro and atrial contractile dysfunction in vivo, indicating insufficient compensation. Atrial cardiomyocyte dysfunction in vitro is induced by the addition of angiotensin II.
Collapse
|
21
|
Kirschner Peretz N, Segal S, Arbel-Ganon L, Ben Jehuda R, Shemer Y, Eisen B, Davoodi M, Binah O, Yaniv Y. A Method Sustaining the Bioelectric, Biophysical, and Bioenergetic Function of Cultured Rabbit Atrial Cells. Front Physiol 2017; 8:584. [PMID: 28860999 PMCID: PMC5559495 DOI: 10.3389/fphys.2017.00584] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 07/31/2017] [Indexed: 12/16/2022] Open
Abstract
Culturing atrial cells leads to a loss in their ability to be externally paced at physiological rates and to maintain their shape. We aim to develop a culture method that sustains the shape of atrial cells along with their biophysical and bioenergetic properties in response to physiological pacing. We hypothesize that adding 2,3-Butanedione 2-monoxime (BDM), which inhibits contraction during the culture period, will preserve these biophysical and bioenergetic properties. Rabbit atrial cells were maintained in culture for 24 h in a medium enriched with a myofilament contraction inhibitor, BDM. The morphology and volume of the cells, including their ability to contract in response to 1–3 Hz electrical pacing, was maintained at the same level as fresh cells. Importantly, the cells could be successfully infected with a GFP adenovirus. Action potentials, Ca2+ transients, and local Ca2+ spark parameters were similar in the cultured and in fresh cells. Finally, these cultured cells' flavoprotein autofluorescence was maintained at a constant level in response to electrical pacing, a response similar to that of fresh cells. Thus, eliminating contraction during the culture period preserves the bioelectric, biophysical and bioenergetic properties of rabbit atrial myocytes. This method therefore has the potential to further improve our understanding of energetic and biochemical regulation in the atria.
Collapse
Affiliation(s)
- Noa Kirschner Peretz
- Biomedical Engineering Faculty, Technion - Israel Institute of TechnologyHaifa, Israel
| | - Sofia Segal
- Biomedical Engineering Faculty, Technion - Israel Institute of TechnologyHaifa, Israel
| | - Limor Arbel-Ganon
- Biomedical Engineering Faculty, Technion - Israel Institute of TechnologyHaifa, Israel
| | - Ronen Ben Jehuda
- Department of Physiology, Biophysics and Systems Biology, Technion - Israel Institute of TechnologyHaifa, Israel.,The Rappaport Institute, The Ruth and Bruce Rappaport Faculty of Medicine, Technion - Israel Institute of TechnologyHaifa, Israel
| | - Yuval Shemer
- Department of Physiology, Biophysics and Systems Biology, Technion - Israel Institute of TechnologyHaifa, Israel.,The Rappaport Institute, The Ruth and Bruce Rappaport Faculty of Medicine, Technion - Israel Institute of TechnologyHaifa, Israel
| | - Binyamin Eisen
- Department of Physiology, Biophysics and Systems Biology, Technion - Israel Institute of TechnologyHaifa, Israel.,The Rappaport Institute, The Ruth and Bruce Rappaport Faculty of Medicine, Technion - Israel Institute of TechnologyHaifa, Israel
| | - Moran Davoodi
- Biomedical Engineering Faculty, Technion - Israel Institute of TechnologyHaifa, Israel
| | - Ofer Binah
- Department of Physiology, Biophysics and Systems Biology, Technion - Israel Institute of TechnologyHaifa, Israel.,The Rappaport Institute, The Ruth and Bruce Rappaport Faculty of Medicine, Technion - Israel Institute of TechnologyHaifa, Israel
| | - Yael Yaniv
- Biomedical Engineering Faculty, Technion - Israel Institute of TechnologyHaifa, Israel
| |
Collapse
|
22
|
Schönleitner P, Schotten U, Antoons G. Mechanosensitivity of microdomain calcium signalling in the heart. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2017. [PMID: 28648626 DOI: 10.1016/j.pbiomolbio.2017.06.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
In cardiac myocytes, calcium (Ca2+) signalling is tightly controlled in dedicated microdomains. At the dyad, i.e. the narrow cleft between t-tubules and junctional sarcoplasmic reticulum (SR), many signalling pathways combine to control Ca2+-induced Ca2+ release during contraction. Local Ca2+ gradients also exist in regions where SR and mitochondria are in close contact to regulate energetic demands. Loss of microdomain structures, or dysregulation of local Ca2+ fluxes in cardiac disease, is often associated with oxidative stress, contractile dysfunction and arrhythmias. Ca2+ signalling at these microdomains is highly mechanosensitive. Recent work has demonstrated that increasing mechanical load triggers rapid local Ca2+ releases that are not reflected by changes in global Ca2+. Key mechanisms involve rapid mechanotransduction with reactive oxygen species or nitric oxide as primary signalling molecules targeting SR or mitochondria microdomains depending on the nature of the mechanical stimulus. This review summarizes the most recent insights in rapid Ca2+ microdomain mechanosensitivity and re-evaluates its (patho)physiological significance in the context of historical data on the macroscopic role of Ca2+ in acute force adaptation and mechanically-induced arrhythmias. We distinguish between preload and afterload mediated effects on local Ca2+ release, and highlight differences between atrial and ventricular myocytes. Finally, we provide an outlook for further investigation in chronic models of abnormal mechanics (eg post-myocardial infarction, atrial fibrillation), to identify the clinical significance of disturbed Ca2+ mechanosensitivity for arrhythmogenesis.
Collapse
Affiliation(s)
- Patrick Schönleitner
- Dept of Physiology, Cardiovascular Research Institute Maastricht, Maastricht University, The Netherlands
| | - Uli Schotten
- Dept of Physiology, Cardiovascular Research Institute Maastricht, Maastricht University, The Netherlands
| | - Gudrun Antoons
- Dept of Physiology, Cardiovascular Research Institute Maastricht, Maastricht University, The Netherlands.
| |
Collapse
|
23
|
Maxwell JT, Blatter LA. A novel mechanism of tandem activation of ryanodine receptors by cytosolic and SR luminal Ca 2+ during excitation-contraction coupling in atrial myocytes. J Physiol 2017; 595:3835-3845. [PMID: 28028837 DOI: 10.1113/jp273611] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Accepted: 12/01/2016] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS In atrial myocytes excitation-contraction coupling is strikingly different from ventricle because atrial myocytes lack a transverse tubule membrane system: Ca2+ release starts in the cell periphery and propagates towards the cell centre by Ca2+ -induced Ca2+ release from the sarcoplasmic reticulum (SR) Ca2+ store. The cytosolic Ca2+ sensitivity of the ryanodine receptor (RyRs) Ca2+ release channel is low and it is unclear how Ca2+ release can be activated in the interior of atrial cells. Simultaneous confocal imaging of cytosolic and intra-SR calcium revealed a transient elevation of store Ca2+ that we termed 'Ca2+ sensitization signal'. We propose a novel paradigm of atrial ECC that is based on tandem activation of the RyRs by cytosolic and luminal Ca2+ through a 'fire-diffuse-uptake-fire' (or FDUF) mechanism: Ca2+ uptake by SR Ca2+ pumps at the propagation front elevates Ca2+ inside the SR locally, leading to luminal RyR sensitization and lowering of the cytosolic Ca2+ activation threshold. ABSTRACT In atrial myocytes Ca2+ release during excitation-contraction coupling (ECC) is strikingly different from ventricular myocytes. In many species atrial myocytes lack a transverse tubule system, dividing the sarcoplasmic reticulum (SR) Ca2+ store into the peripheral subsarcolemmnal junctional (j-SR) and the much more abundant central non-junctional (nj-SR) SR. Action potential (AP)-induced Ca2+ entry activates Ca2+ -induced Ca2+ release (CICR) from j-SR ryanodine receptor (RyR) Ca2+ release channels. Peripheral elevation of [Ca2+ ]i initiates CICR from nj-SR and sustains propagation of CICR to the cell centre. Simultaneous confocal measurements of cytosolic ([Ca2+ ]i ; with the fluorescent Ca2+ indicator rhod-2) and intra-SR ([Ca2+ ]SR ; fluo-5N) Ca2+ in rabbit atrial myocytes revealed that Ca2+ release from j-SR resulted in a cytosolic Ca2+ transient of higher amplitude compared to release from nj-SR; however, the degree of depletion of j-SR [Ca2+ ]SR was smaller than nj-SR [Ca2+ ]SR . Similarly, Ca2+ signals from individual release sites of the j-SR showed a larger cytosolic amplitude (Ca2+ sparks) but smaller depletion (Ca2+ blinks) than release from nj-SR. During AP-induced Ca2+ release the rise of [Ca2+ ]i detected at individual release sites of the nj-SR preceded the depletion of [Ca2+ ]SR , and during this latency period a transient elevation of [Ca2+ ]SR occurred. We propose that Ca2+ release from nj-SR is activated by cytosolic and luminal Ca2+ (tandem RyR activation) via a novel 'fire-diffuse-uptake-fire' (FDUF) mechanism. This novel paradigm of atrial ECC predicts that Ca2+ uptake by sarco-endoplasmic reticulum Ca2+ -ATPase (SERCA) at the propagation front elevates local [Ca2+ ]SR , leading to luminal RyR sensitization and lowering of the activation threshold for cytosolic CICR.
Collapse
Affiliation(s)
- Joshua T Maxwell
- Department of Molecular Biophysics and Physiology, Rush University Medical Centre, Chicago, IL, 60612, USA
| | - Lothar A Blatter
- Department of Molecular Biophysics and Physiology, Rush University Medical Centre, Chicago, IL, 60612, USA
| |
Collapse
|
24
|
Daniels RE, Haq KT, Miller LS, Chia EW, Miura M, Sorrentino V, McGuire JJ, Stuyvers BD. Cardiac expression of ryanodine receptor subtype 3; a strategic component in the intracellular Ca 2+ release system of Purkinje fibers in large mammalian heart. J Mol Cell Cardiol 2017; 104:31-42. [PMID: 28111173 DOI: 10.1016/j.yjmcc.2017.01.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Revised: 12/08/2016] [Accepted: 01/18/2017] [Indexed: 10/20/2022]
Abstract
BACKGROUND Three distinct Ca2+ release channels were identified in dog P-cells: the ryanodine receptor subtype 2 (RyR2) was detected throughout the cell, while the ryanodine receptor subtype 3 (RyR3) and inositol phosphate sensitive Ca2+ release channel (InsP3R) were found in the cell periphery. How each of these channels contributes to the Ca2+ cycling of P-cells is unclear. Recent modeling of Ca2+ mobilization in P-cells suggested that Ca2+ sensitivity of Ca2+induced Ca2+release (CICR) was larger at the P-cell periphery. Our study examined whether this numerically predicted region of Ca2+ release exists in live P-cells. We compared the regional Ca2+ dynamics with the arrangement of intracellular Ca2+ release (CR) channels. METHODS Gene expression of CR channels was measured by qPCR in Purkinje fibers and myocardium of adult Yucatan pig hearts. We characterized the CR channels protein expression in isolated P-cells by immuno-fluorescence, laser scanning confocal microscopy, and 3D reconstruction. The spontaneous Ca2+ activity and electrically-evoked Ca2+ mobilization were imaged by 2D spinning disk confocal microscopy. Functional regions of P-cell were differentiated by the characteristics of local Ca2+ events. We used the Ca2+ propagation velocities as indicators of channel Ca2+ sensitivity. RESULTS RyR2 gene expression was identical in Purkinje fibers and myocardium (6 hearts) while RyR3 and InsP3R gene expressions were, respectively, 100 and 16 times larger in the Purkinje fibers. Specific fluorescent immuno-staining of Ca2+ release channels revealed an intermediate layer of RyR3 expression between a near-membrane InsP3R-region and a central RyR2-region. We found that cell periphery produced two distinct forms of spontaneous Ca2+-transients: (1) large asymmetrical Ca2+ sparks under the membrane, and (2) typical Ca2+-wavelets propagating exclusively around the core of the cell. Larger cell-wide Ca2+ waves (CWWs) appeared occasionally traveling in the longitudinal direction through the core of Pcells. Large sparks arose in a micrometric space overlapping the InsP3R expression. The InsP3R antagonists 2-aminoethoxydiphenyl borate (2-APB; 3μM) and xestospongin C (XeC; 50μM) dramatically reduced their frequency. The Ca2+ wavelets propagated in a 5-10μm thick layered space which matched the intermediate zone of RyR3 expression. The wavelet incidence was unchanged by 2-APB or XeC, but was reduced by 60% in presence of the RyR3 antagonist dantrolene (10μM). The velocity of wavelets was two times larger (86±16μm/s; n=14) compared to CWWs' (46±10μm/s; n=11; P<0.05). Electric stimulation triggered a uniform and large elevation of Ca2+ concentration under the membrane which preceded the propagation of Ca2+ into the interior of the cell. Elevated Cai propagated at 150μm/s (147±34μm/s; n=5) through the region equivalent to the zone of RyR3 expression. This velocity dropped by 50% (75±24μm/s; n=5) in the central region wherein predominant RyR2 expression was detected. CONCLUSION We identified two layers of distinct Ca2+ release channels in the periphery of Pcell: an outer layer of InsP3Rs under the membrane and an inner layer of RyR3s. The propagation of Ca2+ events in these layers revealed that Ca2+ sensitivity of Ca2+ release was larger in the RyR3 layer compared to that of other sub-cellular regions. We propose that RyR3 expression in P-cells plays a role in the stability of electric function of Purkinje fibers.
Collapse
Affiliation(s)
- Rebecca E Daniels
- Faculty of Medicine, Division of Biomedical Sciences, Memorial University of Newfoundland, St. John's, NL, Canada
| | - Kazi T Haq
- Faculty of Medicine, Division of Biomedical Sciences, Memorial University of Newfoundland, St. John's, NL, Canada
| | - Lawson S Miller
- Faculty of Medicine, Division of Biomedical Sciences, Memorial University of Newfoundland, St. John's, NL, Canada
| | - Elizabeth W Chia
- Faculty of Medicine, Division of Biomedical Sciences, Memorial University of Newfoundland, St. John's, NL, Canada
| | - Masahito Miura
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Vincenzo Sorrentino
- Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy
| | - John J McGuire
- Faculty of Medicine, Division of Biomedical Sciences, Memorial University of Newfoundland, St. John's, NL, Canada
| | - Bruno D Stuyvers
- Faculty of Medicine, Division of Biomedical Sciences, Memorial University of Newfoundland, St. John's, NL, Canada.
| |
Collapse
|
25
|
Hohendanner F, DeSantiago J, Heinzel FR, Blatter LA. Dyssynchronous calcium removal in heart failure-induced atrial remodeling. Am J Physiol Heart Circ Physiol 2016; 311:H1352-H1359. [PMID: 27694214 DOI: 10.1152/ajpheart.00375.2016] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 09/26/2016] [Indexed: 11/22/2022]
Abstract
We tested the hypothesis that in atrial myocytes from a rabbit left ventricular heart failure (HF) model, spatial inhomogeneity and temporal dyssynchrony of Ca removal during excitation-contraction coupling together with increased Na/Ca exchange (NCX) activity generate a substrate for proarrhythmic Ca release. Ca removal occurs via Ca reuptake into the sarcoplasmic reticulum and extrusion via NCX exclusively in the cell periphery since rabbit atrial myocytes lack transverse tubules. Ca removal kinetics were assessed by the time constant τ of decay of local peripheral subsarcolemmal (SS) and central (CT) action potential (AP)-induced Ca transients (CaTs) recorded in confocal line scan mode (using Fluo-4). Spatial and temporal dyssynchrony of Ca removal was quantified by CV TAU, defined as the standard deviation of local τ along the transverse cell axis divided by mean τ. In normal cells CT CaT decline was slower compared with the SS domain, while in HF cells decline was accelerated, became equal in SS and CT regions, and a significant increase of CV TAU indicated an increased Ca removal dyssynchrony. In HF atrial cells NCX upregulation was accompanied by an overall higher incidence of spontaneous Ca waves and a higher propensity of arrhythmogenic Ca waves, defined as waves that triggered APs due to NCX-mediated membrane depolarization. NCX inhibition normalized CV TAU in HF atrial cells and decreased the propensity of Ca waves. In summary, HF atrial myocytes show accelerated but dyssynchronous diastolic Ca removal and altered sarcoplasmic reticulum Ca-ATPase (SERCA) and NCX activity that result in increased susceptibility to arrhythmia.
Collapse
Affiliation(s)
- F Hohendanner
- Department of Molecular Biophysics and Physiology, Rush University Medical Center, Chicago, Illinois
| | - J DeSantiago
- Department of Molecular Biophysics and Physiology, Rush University Medical Center, Chicago, Illinois
| | - F R Heinzel
- Department of Molecular Biophysics and Physiology, Rush University Medical Center, Chicago, Illinois
| | - L A Blatter
- Department of Molecular Biophysics and Physiology, Rush University Medical Center, Chicago, Illinois
| |
Collapse
|
26
|
Bootman MD, Rietdorf K. Atrial myocytes demonstrate the diversity of cardiac calcium signalling. Channels (Austin) 2015; 9:219-20. [PMID: 26542624 PMCID: PMC4826100 DOI: 10.1080/15384101.2015.1086203] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/30/2022] Open
Affiliation(s)
- Martin D Bootman
- a Department of Life , Health and Chemical Sciences, The Open University ; Milton Keynes , UK
| | - Katja Rietdorf
- a Department of Life , Health and Chemical Sciences, The Open University ; Milton Keynes , UK
| |
Collapse
|