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Ko SH, Shim JK, Song JW, Soh S, Kwak YL. Inhaled iloprost in off-pump coronary artery bypass surgery: a randomized controlled trial. Can J Anaesth 2024; 71:479-489. [PMID: 38148468 DOI: 10.1007/s12630-023-02672-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 10/05/2023] [Accepted: 10/08/2023] [Indexed: 12/28/2023] Open
Abstract
PURPOSE Mechanical cardiac constraint during off-pump coronary artery bypass surgery (OPCAB) causes right ventricle (RV) compression and increased pulmonary artery pressure (PAP), which may further compromise RV dysfunction. We aimed to assess the effect of inhaled iloprost, a potent selective pulmonary vasodilator, on the cardiac index (CI) during mechanical constraint. The secondary aim was to determine the resultant changes in the hemodynamic and respiratory parameters. METHODS A total of 100 adult patients with three-vessel coronary artery disease who had known risk factors for hemodynamic instability (congestive heart failure, mean PAP ≥ 25 mm Hg, RV systolic pressure ≥ 50 mm Hg on preoperative echocardiography, left ventricular ejection fraction < 50%, myocardial infarction within one month of surgery, redo surgery, and left main disease) were enrolled in a randomized controlled trial. The patients were randomly allocated to the control or iloprost groups at a 1:1 ratio, in which saline and iloprost (20 μg) were inhaled for 15 min after internal mammary artery harvesting, respectively. Cardiac index was measured by pulmonary artery catheterization. RESULTS There were no significant intergroup differences in CI during grafting (P = 0.36). The mean PAP had a significant group-time interaction (P = 0.04) and was significantly lower in the iloprost group at circumflex grafting (mean [standard deviation], 26 [3] mm Hg vs 24 [3] mm Hg; P = 0.01). The remaining hemodynamic parameters were similar between the groups. CONCLUSION Inhaled iloprost showed a neutral effect on hemodynamic parameters, including the CI and pulmonary vascular resistance index, during OPCAB. TRIAL REGISTRATION ClinicalTrials.gov (NCT04598191); first submitted 12 October 2020.
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Affiliation(s)
- Seo Hee Ko
- Department of Anesthesiology and Pain Medicine, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-gu, Seoul, 03722, Republic of Korea
- Anesthesia and Pain Research Institute, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Jae-Kwang Shim
- Department of Anesthesiology and Pain Medicine, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-gu, Seoul, 03722, Republic of Korea
- Anesthesia and Pain Research Institute, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Jong-Wook Song
- Department of Anesthesiology and Pain Medicine, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-gu, Seoul, 03722, Republic of Korea
- Anesthesia and Pain Research Institute, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Sarah Soh
- Department of Anesthesiology and Pain Medicine, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-gu, Seoul, 03722, Republic of Korea
- Anesthesia and Pain Research Institute, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Young-Lan Kwak
- Department of Anesthesiology and Pain Medicine, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-gu, Seoul, 03722, Republic of Korea.
- Anesthesia and Pain Research Institute, Yonsei University College of Medicine, Seoul, Republic of Korea.
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Delgado-Betancourt V, Chinda K, Mesirca P, Barrère C, Covinhes A, Gallot L, Vincent A, Bidaud I, Kumphune S, Nargeot J, Piot C, Wickman K, Mangoni ME, Barrère-Lemaire S. Heart rate reduction after genetic ablation of L-type Ca v1.3 channels induces cardioprotection against ischemia-reperfusion injury. Front Cardiovasc Med 2023; 10:1134503. [PMID: 37593151 PMCID: PMC10429177 DOI: 10.3389/fcvm.2023.1134503] [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: 12/30/2022] [Accepted: 06/21/2023] [Indexed: 08/19/2023] Open
Abstract
Background Acute myocardial infarction (AMI) is the major cause of cardiovascular mortality worldwide. Most ischemic episodes are triggered by an increase in heart rate, which induces an imbalance between myocardial oxygen delivery and consumption. Developing drugs that selectively reduce heart rate by inhibiting ion channels involved in heart rate control could provide more clinical benefits. The Cav1.3-mediated L-type Ca2+ current (ICav1.3) play important roles in the generation of heart rate. Therefore, they can constitute relevant targets for selective control of heart rate and cardioprotection during AMI. Objective We aimed to investigate the relationship between heart rate and infarct size using mouse strains knockout for Cav1.3 (Cav1.3-/-) L-type calcium channel and of the cardiac G protein gated potassium channel (Girk4-/-) in association with the funny (f)-channel inhibitor ivabradine. Methods Wild-type (WT), Cav1.3+/-, Cav1.3-/- and Girk4-/- mice were used as models of respectively normal heart rate, moderate heart rate reduction, bradycardia, and mild tachycardia, respectively. Mice underwent a surgical protocol of myocardial IR (40 min ischemia and 60 min reperfusion). Heart rate was recorded by one-lead surface ECG recording, and infarct size measured by triphenyl tetrazolium chloride staining. In addition, Cav1.3-/- and WT hearts perfused on a Langendorff system were subjected to the same ischemia-reperfusion protocol ex vivo, without or with atrial pacing, and the coronary flow was recorded. Results Cav1.3-/- mice presented reduced infarct size (-29%), while Girk4-/- displayed increased infarct size (+30%) compared to WT mice. Consistently, heart rate reduction in Cav1.3+/- or by the f-channel blocker ivabradine was associated with significant decrease in infarct size (-27% and -32%, respectively) in comparison to WT mice. Conclusion Our results show that decreasing heart rate allows to protect the myocardium against IR injury in vivo and reveal a close relationship between basal heart rate and IR injury. In addition, this study suggests that targeting Cav1.3 channels could constitute a relevant target for reducing infarct size, since maximal heart rate dependent cardioprotective effect is already observed in Cav1.3+/- mice.
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Affiliation(s)
- Viviana Delgado-Betancourt
- Institut de Génomique Fonctionnelle, Université Montpellier, CNRS, INSERM, Montpellier, France
- LabEx Ion Channel Science & Therapeutics (ICST), Université de Nice, Valbonne, France
| | - Kroekkiat Chinda
- Institut de Génomique Fonctionnelle, Université Montpellier, CNRS, INSERM, Montpellier, France
- Department of Physiology, Faculty of Medical Science, Naresuan University, Phitsanulok, Thailand
| | - Pietro Mesirca
- Institut de Génomique Fonctionnelle, Université Montpellier, CNRS, INSERM, Montpellier, France
- LabEx Ion Channel Science & Therapeutics (ICST), Université de Nice, Valbonne, France
| | - Christian Barrère
- Institut de Génomique Fonctionnelle, Université Montpellier, CNRS, INSERM, Montpellier, France
- LabEx Ion Channel Science & Therapeutics (ICST), Université de Nice, Valbonne, France
| | - Aurélie Covinhes
- Institut de Génomique Fonctionnelle, Université Montpellier, CNRS, INSERM, Montpellier, France
- LabEx Ion Channel Science & Therapeutics (ICST), Université de Nice, Valbonne, France
| | - Laura Gallot
- Institut de Génomique Fonctionnelle, Université Montpellier, CNRS, INSERM, Montpellier, France
- LabEx Ion Channel Science & Therapeutics (ICST), Université de Nice, Valbonne, France
| | - Anne Vincent
- Institut de Génomique Fonctionnelle, Université Montpellier, CNRS, INSERM, Montpellier, France
- LabEx Ion Channel Science & Therapeutics (ICST), Université de Nice, Valbonne, France
| | - Isabelle Bidaud
- Institut de Génomique Fonctionnelle, Université Montpellier, CNRS, INSERM, Montpellier, France
- LabEx Ion Channel Science & Therapeutics (ICST), Université de Nice, Valbonne, France
| | - Sarawut Kumphune
- Biomedical Engineering Institute (BMEi), Chiang Mai University, Chiang Mai, Thailand
| | - Joël Nargeot
- Institut de Génomique Fonctionnelle, Université Montpellier, CNRS, INSERM, Montpellier, France
- LabEx Ion Channel Science & Therapeutics (ICST), Université de Nice, Valbonne, France
| | - Christophe Piot
- Institut de Génomique Fonctionnelle, Université Montpellier, CNRS, INSERM, Montpellier, France
- LabEx Ion Channel Science & Therapeutics (ICST), Université de Nice, Valbonne, France
- Département de Cardiologie Interventionnelle, Clinique du Millénaire, Montpellier, France
| | - Kevin Wickman
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, United States
| | - Matteo Elia Mangoni
- Institut de Génomique Fonctionnelle, Université Montpellier, CNRS, INSERM, Montpellier, France
- LabEx Ion Channel Science & Therapeutics (ICST), Université de Nice, Valbonne, France
| | - Stéphanie Barrère-Lemaire
- Institut de Génomique Fonctionnelle, Université Montpellier, CNRS, INSERM, Montpellier, France
- LabEx Ion Channel Science & Therapeutics (ICST), Université de Nice, Valbonne, France
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3
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Lässing J, Maudrich T, Kenville R, Uyar Z, Bischoff C, Fikenzer S, Busse M, Falz R. Intensity-dependent cardiopulmonary response during and after strength training. Sci Rep 2023; 13:6632. [PMID: 37095279 PMCID: PMC10126007 DOI: 10.1038/s41598-023-33873-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Accepted: 04/20/2023] [Indexed: 04/26/2023] Open
Abstract
Whereas cardiopulmonary responses are well understood in endurance training, they are rarely described in strength training. This cross-over study examined acute cardiopulmonary responses in strength training. Fourteen healthy male strength training-experienced participants (age 24.5 ± 2.9 years; BMI 24.1 ± 2.0 kg/m2) were randomly assigned into three strength training sessions (three sets of ten repetitions) with different intensities (50%, 62,5%, and 75% of the 3-Repetition Maximum) of squats in a smith machine. Cardiopulmonary (impedance cardiography, ergo-spirometry) responses were continuously monitored. During exercise period, heart rate (HR 143 ± 16 vs. 132 ± 15 vs. 129 ± 18 bpm, respectively; p < 0.01; η2p 0.54) and cardiac output (CO: 16.7 ± 3.7 vs. 14.3 ± 2.5 vs. 13.6 ± 2.4 l/min, respectively; p < 0.01; η2p 0.56) were higher at 75% of 3-RM compared to those at the other intensities. We noted similar stroke volume (SV: p = 0.08; η2p 0.18) and end-diastolic volume (EDV: p = 0.49). Ventilation (VE) was higher at 75% compared to 62.5% and 50% (44.0 ± 8.0 vs. 39.6 ± 10.4 vs. 37.6 ± 7.7 l/min, respectively; p < 0.01; η2p 0.56). Respiration rate (RR; p = .16; η2p 0.13), tidal volume (VT: p = 0.41; η2p 0.07) and oxygen uptake (VO2: p = 0.11; η2p 0.16) did not differ between intensities. High systolic and diastolic blood pressure were evident (62.5% 3-RM 197 ± 22.4/108.8 ± 13.4 mmHG). During the post-exercise period (60 s), SV, CO, VE, VO2, and VCO2 were higher (p < 0.01) than during the exercise period, and the pulmonary parameters differed markedly between intensities (VE p < 0.01; RR p < 0.01; VT p = 0.02; VO2 p < 0.01; VCO2 p < 0.01). Despite the differences in strength training intensity, the cardiopulmonary response reveals significant differences predominantly during the post-exercise period. Intensity-induced breath holding induces high blood pressure peaks and cardiopulmonary recovery effects after exercise.
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Affiliation(s)
- Johannes Lässing
- Department of Exercise Science and Sports Medicine, Martin Luther University Halle-Wittenberg, Von-Seckendorff-Platz 2, 06120, Halle (Saale), Germany
| | - Tom Maudrich
- Department of Movement Neuroscience, Faculty of Sports Science, Leipzig University, 04109, Leipzig, Germany
| | - Rouven Kenville
- Department of Movement Neuroscience, Faculty of Sports Science, Leipzig University, 04109, Leipzig, Germany
| | - Zarah Uyar
- Institute of Sport Medicine and Prevention, University of Leipzig, Rosa-Luxemburg-Straße 20-30, 04103, Leipzig, Germany
| | - Christian Bischoff
- Institute of Sport Medicine and Prevention, University of Leipzig, Rosa-Luxemburg-Straße 20-30, 04103, Leipzig, Germany
| | - Sven Fikenzer
- Klinik und Poliklinik für Kardiologie, Universitätsklinikum Leipzig, Liebigstr. 20, 04103, Leipzig, Germany
| | - Martin Busse
- Institute of Sport Medicine and Prevention, University of Leipzig, Rosa-Luxemburg-Straße 20-30, 04103, Leipzig, Germany
| | - Roberto Falz
- Institute of Sport Medicine and Prevention, University of Leipzig, Rosa-Luxemburg-Straße 20-30, 04103, Leipzig, Germany.
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4
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Charest-Pekeski AJ, Cho SKS, Aujla T, Sun L, Floh AA, McVey MJ, Sheta A, Estrada M, Crawford-Lean L, Foreman C, Mroczek D, Belik J, Saini BS, Lim JM, Moir OJ, Lee FT, Quinn M, Darby JRT, Seed M, Morrison JL, Haller C. Impact of the Addition of a Centrifugal Pump in a Preterm Miniature Pig Model of the Artificial Placenta. Front Physiol 2022; 13:925772. [PMID: 35941934 PMCID: PMC9356302 DOI: 10.3389/fphys.2022.925772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Accepted: 06/22/2022] [Indexed: 11/28/2022] Open
Abstract
The recent demonstration of normal development of preterm sheep in an artificial extrauterine environment has renewed interest in artificial placenta (AP) systems as a potential treatment strategy for extremely preterm human infants. However, the feasibility of translating this technology to the human preterm infant remains unknown. Here we report the support of 13 preterm fetal pigs delivered at 102 ± 4 days (d) gestation, weighing 616 ± 139 g with a circuit consisting of an oxygenator and a centrifugal pump, comparing these results with our previously reported pumpless circuit (n = 12; 98 ± 4 days; 743 ± 350 g). The umbilical vessels were cannulated, and fetuses were supported for 46.4 ± 46.8 h using the pumped AP versus 11 ± 13 h on the pumpless AP circuit. Upon initiation of AP support on the pumped system, we observed supraphysiologic circuit flows, tachycardia, and hypertension, while animals maintained on a pumpless AP circuit exhibited subphysiologic flows. On the pumped AP circuit, there was a progressive decline in umbilical vein (UV) flow and oxygen delivery. We conclude that the addition of a centrifugal pump to the AP circuit improves survival of preterm pigs by augmenting UV flow through the reduction of right ventricular afterload. However, we continued to observe the development of heart failure within a matter of days.
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Affiliation(s)
- Alex J. Charest-Pekeski
- Department of Physiology, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
- Translational Medicine, The Hospital for Sick Children, Toronto, ON, Canada
| | - Steven K. S. Cho
- Department of Physiology, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
- Translational Medicine, The Hospital for Sick Children, Toronto, ON, Canada
- Early Origins of Adult Health Research Group, Health and Biomedical Innovation, UniSA: Clinical and Health Sciences, University of South Australia, Adelaide, SA, Australia
| | - Tanroop Aujla
- Department of Physiology, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
- Translational Medicine, The Hospital for Sick Children, Toronto, ON, Canada
| | - Liqun Sun
- Division of Cardiology, The Labatt Family Heart Centre, The Hospital for Sick Children, Toronto, ON, Canada
| | - Alejandro A. Floh
- Division of Cardiology, The Labatt Family Heart Centre, The Hospital for Sick Children, Toronto, ON, Canada
- Department of Critical Care Medicine, The Hospital for Sick Children, Toronto, ON, Canada
| | - Mark J. McVey
- Translational Medicine, The Hospital for Sick Children, Toronto, ON, Canada
- Department of Anesthesiology and Pain Medicine, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
- Department of Physics, Ryerson University, Toronto, ON, Canada
| | - Ayman Sheta
- Department of Pediatrics, Division of Neonatology, The Hospital for Sick Children, Toronto, ON, Canada
| | - Marvin Estrada
- Lab Animal Services, Peter Gilgan Center for Research and Learning, The Hospital for Sick Children, Toronto, ON, Canada
| | - Lynn Crawford-Lean
- Division of Cardiovascular Surgery, The Labatt Family Heart Centre, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
| | - Celeste Foreman
- Division of Cardiovascular Surgery, The Labatt Family Heart Centre, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
| | - Dariusz Mroczek
- Division of Cardiology, The Labatt Family Heart Centre, The Hospital for Sick Children, Toronto, ON, Canada
| | - Jaques Belik
- Department of Pediatrics, Division of Neonatology, The Hospital for Sick Children, Toronto, ON, Canada
| | - Brahmdeep S. Saini
- Translational Medicine, The Hospital for Sick Children, Toronto, ON, Canada
- Institute of Medical Science, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Jessie Mei Lim
- Department of Physiology, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
- Translational Medicine, The Hospital for Sick Children, Toronto, ON, Canada
| | - Olivia J. Moir
- Department of Physiology, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
- Translational Medicine, The Hospital for Sick Children, Toronto, ON, Canada
| | - Fu-Tsuen Lee
- Department of Physiology, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
- Translational Medicine, The Hospital for Sick Children, Toronto, ON, Canada
| | - Megan Quinn
- Early Origins of Adult Health Research Group, Health and Biomedical Innovation, UniSA: Clinical and Health Sciences, University of South Australia, Adelaide, SA, Australia
| | - Jack R. T. Darby
- Early Origins of Adult Health Research Group, Health and Biomedical Innovation, UniSA: Clinical and Health Sciences, University of South Australia, Adelaide, SA, Australia
| | - Mike Seed
- Department of Physiology, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
- Division of Cardiology, The Labatt Family Heart Centre, The Hospital for Sick Children, Toronto, ON, Canada
- Institute of Medical Science, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Janna L. Morrison
- Department of Physiology, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
- Translational Medicine, The Hospital for Sick Children, Toronto, ON, Canada
- Early Origins of Adult Health Research Group, Health and Biomedical Innovation, UniSA: Clinical and Health Sciences, University of South Australia, Adelaide, SA, Australia
| | - Christoph Haller
- Division of Cardiovascular Surgery, The Labatt Family Heart Centre, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
- *Correspondence: Christoph Haller,
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5
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Edwards AG, Mørk H, Stokke MK, Lipsett DB, Sjaastad I, Richard S, Sejersted OM, Louch WE. Sarcoplasmic Reticulum Calcium Release Is Required for Arrhythmogenesis in the Mouse. Front Physiol 2021; 12:744730. [PMID: 34712150 PMCID: PMC8546347 DOI: 10.3389/fphys.2021.744730] [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: 07/20/2021] [Accepted: 09/20/2021] [Indexed: 11/23/2022] Open
Abstract
Dysfunctional sarcoplasmic reticulum Ca2+ handling is commonly observed in heart failure, and thought to contribute to arrhythmogenesis through several mechanisms. Some time ago we developed a cardiomyocyte-specific inducible SERCA2 knockout mouse, which is remarkable in the degree to which major adaptations to sarcolemmal Ca2+ entry and efflux overcome the deficit in SR reuptake to permit relatively normal contractile function. Conventionally, those adaptations would also be expected to dramatically increase arrhythmia susceptibility. However, that susceptibility has never been tested, and it is possible that the very rapid repolarization of the murine action potential (AP) allows for large changes in sarcolemmal Ca2+ transport without substantially disrupting electrophysiologic stability. We investigated this hypothesis through telemetric ECG recording in the SERCA2-KO mouse, and patch-clamp electrophysiology, Ca2+ imaging, and mathematical modeling of isolated SERCA2-KO myocytes. While the SERCA2-KO animals exhibit major (and unique) electrophysiologic adaptations at both the organ and cell levels, they remain resistant to arrhythmia. A marked increase in peak L-type calcium (ICaL) current and slowed ICaL decay elicited pronounced prolongation of initial repolarization, but faster late repolarization normalizes overall AP duration. Early afterdepolarizations were seldom observed in KO animals, and those that were observed exhibited a mechanism intermediate between murine and large mammal dynamical properties. As expected, spontaneous SR Ca2+ sparks and waves were virtually absent. Together these findings suggest that intact SR Ca2+ handling is an absolute requirement for triggered arrhythmia in the mouse, and that in its absence, dramatic changes to the major inward currents can be resisted by the substantial K+ current reserve, even at end-stage disease.
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Affiliation(s)
- Andrew G Edwards
- Institute for Experimental Medical Research, Oslo University Hospital, University of Oslo, Oslo, Norway.,Department of Pharmacology, University of California, Davis, Davis, CA, United States
| | - Halvor Mørk
- Institute for Experimental Medical Research, Oslo University Hospital, University of Oslo, Oslo, Norway
| | - Mathis K Stokke
- Institute for Experimental Medical Research, Oslo University Hospital, University of Oslo, Oslo, Norway.,K.G. Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway.,Department of Cardiology, Oslo University Hospital, Oslo, Norway
| | - David B Lipsett
- Institute for Experimental Medical Research, Oslo University Hospital, University of Oslo, Oslo, Norway
| | - Ivar Sjaastad
- Institute for Experimental Medical Research, Oslo University Hospital, University of Oslo, Oslo, Norway.,K.G. Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
| | - Sylvain Richard
- Université de Montpellier, INSERM, CNRS, PhyMedExp, Montpellier, France
| | - Ole M Sejersted
- Institute for Experimental Medical Research, Oslo University Hospital, University of Oslo, Oslo, Norway
| | - William E Louch
- Institute for Experimental Medical Research, Oslo University Hospital, University of Oslo, Oslo, Norway.,K.G. Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
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6
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Crocini C, Gotthardt M. Cardiac sarcomere mechanics in health and disease. Biophys Rev 2021; 13:637-652. [PMID: 34745372 PMCID: PMC8553709 DOI: 10.1007/s12551-021-00840-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Accepted: 08/27/2021] [Indexed: 12/23/2022] Open
Abstract
The sarcomere is the fundamental structural and functional unit of striated muscle and is directly responsible for most of its mechanical properties. The sarcomere generates active or contractile forces and determines the passive or elastic properties of striated muscle. In the heart, mutations in sarcomeric proteins are responsible for the majority of genetically inherited cardiomyopathies. Here, we review the major determinants of cardiac sarcomere mechanics including the key structural components that contribute to active and passive tension. We dissect the molecular and structural basis of active force generation, including sarcomere composition, structure, activation, and relaxation. We then explore the giant sarcomere-resident protein titin, the major contributor to cardiac passive tension. We discuss sarcomere dynamics exemplified by the regulation of titin-based stiffness and the titin life cycle. Finally, we provide an overview of therapeutic strategies that target the sarcomere to improve cardiac contraction and filling.
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Affiliation(s)
- Claudia Crocini
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Neuromuscular and Cardiovascular Cell Biology, Berlin, Germany
- German Center for Cardiovascular Research (DZHK) Partner Site Berlin, Berlin, Germany
- BioFrontiers Institute & Department of Molecular and Cellular Development, University of Colorado Boulder, Boulder, USA
| | - Michael Gotthardt
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Neuromuscular and Cardiovascular Cell Biology, Berlin, Germany
- German Center for Cardiovascular Research (DZHK) Partner Site Berlin, Berlin, Germany
- Charité-Universitätsmedizin Berlin, 10117 Berlin, Germany
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7
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Patey O, Gatzoulis MA, Thilaganathan B, Carvalho JS. Perinatal Changes in Fetal Ventricular Geometry, Myocardial Performance, and Cardiac Function in Normal Term Pregnancies. J Am Soc Echocardiogr 2017; 30:485-492.e5. [DOI: 10.1016/j.echo.2017.01.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Indexed: 01/22/2023]
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8
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De Pauw M, Mubagwa K, Hodeige D, Borgers M, Flameng W, Van de Voorde J, Heyndrickx GR. Response to exercise and mechanical efficiency in non-ischaemic stunning, induced by short-term rapid pacing in dogs: a role for calcium? Acta Physiol (Oxf) 2017; 219:768-780. [PMID: 26560191 DOI: 10.1111/apha.12629] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Revised: 06/02/2015] [Accepted: 11/04/2015] [Indexed: 11/28/2022]
Abstract
AIM Rapid pacing (RP) is a regularly used model to induce heart failure in dogs. The aim of the study was to evaluate Ca2+ handling, left ventricular (LV) contractile response during Ca2+ administration compared to exercise, as well as oxygen consumption and mechanical efficiency after 48 h of RP. METHODS Fifty-three mongrel dogs were instrumented to measure LV pressure, LV fractional shortening, regional wall thickening and coronary blood flow. Contractile reserve was measured with isoproterenol and intravenous (IV) Ca2+ administration. To assess the function of the sarcoplasmic reticulum (SR), post-extrasystolic potentiation (PESP) and SR Ca2+ uptake were measured. A graded treadmill test was performed in baseline and after RP (n = 14). In a separate group of animals (n = 5), myocardial performance and oxygen consumption were measured using a wide range of loading conditions. RESULTS Left ventricular contractility was significantly decreased upon cessation of pacing. The contractile response to isoproterenol was blunted compared to a preserved response to IV Ca2+ . Post-extrasystolic potentiation was slightly increased after RP. Maximal velocity (Vmax ) of SR Ca2+ uptake was unchanged. Contractile response during exercise is attenuated after RP. External work is reduced, whereas oxygen consumption is preserved, provoking a reduced mechanical efficiency. CONCLUSION Forty-eight-hours RP provokes a reversible LV dysfunction, while the SR function and response to exogenous Ca2+ are preserved. This is compatible with an intracellular functional remodelling to counteract Ca2+ overload provoked by RP. Left ventricular dysfunction is accompanied by a reduced contractile reserve, but an unchanged oxygen consumption, illustrating an alteration in oxygen utilization.
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Affiliation(s)
- M. De Pauw
- The Department of Cardiology; Ghent University Hospital; Ghent Belgium
| | - K. Mubagwa
- Unit of Experimental Cardiac Surgery; Department of Cardiovascular Sciences; University of Leuven; Leuven Belgium
| | - D. Hodeige
- University of Louvain Medical School Brussels; Brussels Belgium
| | - M. Borgers
- The Janssen Research Foundation; Beerse Belgium
| | - W. Flameng
- Unit of Experimental Cardiac Surgery; Department of Cardiovascular Sciences; University of Leuven; Leuven Belgium
| | | | - G. R. Heyndrickx
- University of Louvain Medical School Brussels; Brussels Belgium
- Cardiovascular Center Aalst; Aalst Belgium
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9
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Wada Y, Aiba T, Tsujita Y, Itoh H, Wada M, Nakajima I, Ishibashi K, Okamura H, Miyamoto K, Noda T, Sugano Y, Kanzaki H, Anzai T, Kusano K, Yasuda S, Horie M, Ogawa H. Practical applicability of landiolol, an ultra-short-acting β1-selective blocker, for rapid atrial and ventricular tachyarrhythmias with left ventricular dysfunction. J Arrhythm 2015; 32:82-8. [PMID: 27092187 PMCID: PMC4823575 DOI: 10.1016/j.joa.2015.09.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Revised: 08/15/2015] [Accepted: 09/08/2015] [Indexed: 12/18/2022] Open
Abstract
Background Landiolol effectively controls rapid heart rate in atrial fibrillation or flutter (AF/AFL) patients with left ventricular (LV) dysfunction. However, predicting landiolol Responders and Non-Responders and patients who will experience adverse effects remains a challenge. The aim of this study was to clarify the potential applicability of landiolol for rapid AF/AFL and refractory ventricular tachyarrhythmias (VTs) in patients with heart failure. Methods A total of 39 patients with AF/AFL with ventricular response ≥120 bpm and 12 VTs were retrospectively enrolled. Landiolol Responders for rapid AF/AFL were defined as patients whose ventricular response was suppressed to less than 110 bpm or decreased by ≥20% from the initial heart rate after administration of landiolol. Responders for VTs were defined as patients with no recurrent VTs during the 24 h after the initiation of landiolol. Results For AF/AFL, 29 patients (74%) were Responders. In nine patients (31%), AF was spontaneously terminated after starting landiolol. Eight Non-Responders (80%) needed to have AF terminated by cardioversion. Left ventricular ejection fraction (LVEF) at baseline was significantly associated with landiolol efficacy. For VTs, seven patients (58%) were Responders, and smaller LV diastolic and systolic diameters were associated with landiolol efficacy. Hypotension after landiolol treatment occurred in 5 of 51 patients, and lower LV systolic function was associated with the development of adverse events. Conclusions Landiolol is effective in patients with heart failure not only due to rapid AF/AFL but also due to VTs. However, preserved LVEF is important for efficacy and safety in landiolol treatment.
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Affiliation(s)
- Yuko Wada
- Department of Cardiovascular Medicine, National Cerebral and Cardiovascular Center, Suita, Japan; Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Japan
| | - Takeshi Aiba
- Department of Cardiovascular Medicine, National Cerebral and Cardiovascular Center, Suita, Japan
| | - Yasuyuki Tsujita
- Department of Critical and Intensive Care Medicine, Shiga University of Medical Science, Otsu, Japan
| | - Hideki Itoh
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Japan
| | - Mitsuru Wada
- Department of Cardiovascular Medicine, National Cerebral and Cardiovascular Center, Suita, Japan
| | - Ikutaro Nakajima
- Department of Cardiovascular Medicine, National Cerebral and Cardiovascular Center, Suita, Japan
| | - Kohei Ishibashi
- Department of Cardiovascular Medicine, National Cerebral and Cardiovascular Center, Suita, Japan
| | - Hideo Okamura
- Department of Cardiovascular Medicine, National Cerebral and Cardiovascular Center, Suita, Japan
| | - Koji Miyamoto
- Department of Cardiovascular Medicine, National Cerebral and Cardiovascular Center, Suita, Japan
| | - Takashi Noda
- Department of Cardiovascular Medicine, National Cerebral and Cardiovascular Center, Suita, Japan
| | - Yasuo Sugano
- Department of Cardiovascular Medicine, National Cerebral and Cardiovascular Center, Suita, Japan
| | - Hideaki Kanzaki
- Department of Cardiovascular Medicine, National Cerebral and Cardiovascular Center, Suita, Japan
| | - Toshihisa Anzai
- Department of Cardiovascular Medicine, National Cerebral and Cardiovascular Center, Suita, Japan
| | - Kengo Kusano
- Department of Cardiovascular Medicine, National Cerebral and Cardiovascular Center, Suita, Japan
| | - Satoshi Yasuda
- Department of Cardiovascular Medicine, National Cerebral and Cardiovascular Center, Suita, Japan
| | - Minoru Horie
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Japan
| | - Hisao Ogawa
- Department of Cardiovascular Medicine, National Cerebral and Cardiovascular Center, Suita, Japan
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Locatelli J, de Assis LVM, Isoldi MC. Calcium handling proteins: structure, function, and modulation by exercise. Heart Fail Rev 2014; 19:207-25. [PMID: 23436107 DOI: 10.1007/s10741-013-9373-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Heart failure is a serious public health issue with a growing prevalence, and it is related with the aging of the population. Hypertension is identified as the main precursor of left ventricular hypertrophy and therefore can lead to diastolic dysfunction and heart failure. Scientific studies have confirmed the beneficial effects of the physical exercise by reducing the blood pressure and improving the functional status of the heart in hypertension. Several proteins are involved in the mobilization of calcium during the coupling excitation-contraction process in the heart among those are sarcoplasmic reticulum Ca(2+)-ATPase, phospholamban, calsequestrin, sodium-calcium exchanger, L-type calcium's channel, and ryanodine receptors. Our goal is to address the beneficial effects of exercise on the calcium handling proteins in a heart with hypertension.
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Affiliation(s)
- Jamille Locatelli
- Institute of Exact and Biological Sciences, Federal University of Ouro Preto, Ouro Prêto, Brazil
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11
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Lehto T, Castillo Alvarez A, Gauck S, Gait MJ, Coursindel T, Wood MJA, Lebleu B, Boisguerin P. Cellular trafficking determines the exon skipping activity of Pip6a-PMO in mdx skeletal and cardiac muscle cells. Nucleic Acids Res 2013; 42:3207-17. [PMID: 24366877 PMCID: PMC3950666 DOI: 10.1093/nar/gkt1220] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Cell-penetrating peptide-mediated delivery of phosphorodiamidate morpholino oligomers (PMOs) has shown great promise for exon-skipping therapy of Duchenne Muscular Dystrophy (DMD). Pip6a-PMO, a recently developed conjugate, is particularly efficient in a murine DMD model, although mechanisms responsible for its increased biological activity have not been studied. Here, we evaluate the cellular trafficking and the biological activity of Pip6a-PMO in skeletal muscle cells and primary cardiomyocytes. Our results indicate that Pip6a-PMO is taken up in the skeletal muscle cells by an energy- and caveolae-mediated endocytosis. Interestingly, its cellular distribution is different in undifferentiated and differentiated skeletal muscle cells (vesicular versus nuclear). Likewise, Pip6a-PMO mainly accumulates in cytoplasmic vesicles in primary cardiomyocytes, in which clathrin-mediated endocytosis seems to be the pre-dominant uptake pathway. These differences in cellular trafficking correspond well with the exon-skipping data, with higher activity in myotubes than in myoblasts or cardiomyocytes. These differences in cellular trafficking thus provide a possible mechanistic explanation for the variations in exon-skipping activity and restoration of dystrophin protein in heart muscle compared with skeletal muscle tissues in DMD models. Overall, Pip6a-PMO appears as the most efficient conjugate to date (low nanomolar EC50), even if limitations remain from endosomal escape.
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Affiliation(s)
- Taavi Lehto
- UMR 5235 CNRS, Université Montpellier 2, Place Eugene Bataillon, Montpellier 34095, France, Centre de Recherche de Biochimie Macromoléculaire, UMR 5237 CNRS, 1919 Route de Mende, 34293 Montpellier, France, Universität Potsdam, Institut für Biochemie und Biologie, Maulbeerallee 2, 14469 Potsdam, Germany, Medical Research Council, Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK and Department of Physiology, Anatomy and Genetics, University of Oxford, South Parks Road, Oxford, OX1 3QX, UK
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12
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Bombardini T, Zoppè M, Ciampi Q, Cortigiani L, Agricola E, Salvadori S, Loni T, Pratali L, Picano E. Myocardial contractility in the stress echo lab: from pathophysiological toy to clinical tool. Cardiovasc Ultrasound 2013; 11:41. [PMID: 24246005 PMCID: PMC3875530 DOI: 10.1186/1476-7120-11-41] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Accepted: 11/15/2013] [Indexed: 11/10/2022] Open
Abstract
Up-regulation of Ca2+ entry through Ca2+ channels by high rates of beating is involved in the frequency-dependent regulation of contractility: this process is crucial in adaptation to exercise and stress and is universally known as force-frequency relation (FFR). Disturbances in calcium handling play a central role in the disturbed contractile function in myocardial failure. Measurements of twitch tension in isolated left-ventricular strips from explanted cardiomyopathic hearts compared with non-failing hearts show flat or biphasic FFR, while it is up-sloping in normal hearts. Starting in 2003 we introduced the FFR measurement in the stress echo lab using the end-systolic pressure (ESP)/End-systolic volume index (ESVi) ratio (the Suga index) at increasing heart rates. We studied a total of 2,031 patients reported in peer-reviewed journals: 483 during exercise, 34 with pacing, 850 with dobutamine and 664 during dipyridamole stress echo. We demonstrated the feasibility of FFR in the stress echo lab, the clinical usefulness of FFR for diagnosing latent contractile dysfunction in apparently normal hearts, and residual contractile reserve in dilated idiopathic and ischemic cardiomyopathy. In 400 patients with left ventricular dysfunction (ejection fraction 30 ± 9%) with negative stress echocardiography results, event-free survival was higher (p < 0.001) in patients with ΔESPVR (the difference between peak and rest end-systolic pressure-volume ratio, ESPVR) ≥ 0.4 mmHg/mL/m2. The prognostic stratification of patients was better with FFR, beyond the standard LV ejection fraction evaluation, also in the particular settings of severe mitral regurgitation or diabetics without stress-induced ischemia. In the particular setting of selection of heart transplant donors, the stress echo FFR was able to correctly select 34 marginal donor hearts efficiently transplanted in emergency recipients. Starting in 2007, we introduced an operator-independent cutaneous sensor to monitor the FFR: the force is quantified as the sensed pre-ejection myocardial vibration amplitude. We demonstrated that the sensor-derived force changes at increasing heart rates are highly related with both max dP/dt in animal models, and with the stress echo FFR in 220 humans, opening a new window for pervasive cardiac heart failure monitoring in telemedicine systems.
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Affiliation(s)
- Tonino Bombardini
- CNR, Institute of Clinical Physiology, Area della Ricerca, Pisa 56124, Italy.
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13
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Jung YJ, Kim SE, Hong JY, Lee JH, Park DG, Han KR, Oh DJ. Reversible dilated cardiomyopathy caused by idiopathic hypoparathyroidism. Korean J Intern Med 2013; 28:605-8. [PMID: 24009458 PMCID: PMC3759768 DOI: 10.3904/kjim.2013.28.5.605] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Revised: 05/03/2012] [Accepted: 06/22/2012] [Indexed: 11/27/2022] Open
Abstract
Dilated cardiomyopathy (DCM) is usually an idiopathic disease with a poor prognosis. Hypocalcemia is a rare and reversible cause of DCM. Here, we report a 50-year-old female with DCM, induced by idiopathic hypoparathyroidism, that improved after treatment with calcium.
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Affiliation(s)
- Youn Joo Jung
- Division of Cardiology, Department of Internal Medicine, Hallym University Kangdong Sacred Heart Hospital, Seoul, Korea
| | - Sung Eun Kim
- Division of Cardiology, Department of Internal Medicine, Hallym University Kangdong Sacred Heart Hospital, Seoul, Korea
| | - Ji Yeon Hong
- Division of Cardiology, Department of Internal Medicine, Hallym University Kangdong Sacred Heart Hospital, Seoul, Korea
| | - Jun Hee Lee
- Division of Cardiology, Department of Internal Medicine, Hallym University Kangdong Sacred Heart Hospital, Seoul, Korea
| | - Dae Gyun Park
- Division of Cardiology, Department of Internal Medicine, Hallym University Kangdong Sacred Heart Hospital, Seoul, Korea
| | - Kyoo Rok Han
- Division of Cardiology, Department of Internal Medicine, Hallym University Kangdong Sacred Heart Hospital, Seoul, Korea
| | - Dong Jin Oh
- Division of Cardiology, Department of Internal Medicine, Hallym University Kangdong Sacred Heart Hospital, Seoul, Korea
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14
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Ahtarovski KA, Iversen KK, Lønborg JT, Madsen PL, Engstrøm T, Vejlstrup N. Left atrial and ventricular function during dobutamine and glycopyrrolate stress in healthy young and elderly as evaluated by cardiac magnetic resonance. Am J Physiol Heart Circ Physiol 2012; 303:H1469-73. [DOI: 10.1152/ajpheart.00365.2012] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The aim of this study is to describe phasic volume changes of the left atrium (LA) in healthy young and elderly subjects at rest and during pharmacological stress (PS). LA maximum size is related to cardiovascular mortality. LA has passive, active, and conduit function for left ventricular (LV) filling. We hypothesized that changes in LV compliance from normal aging are reflected in LA volume changes and that PS will augment these differences. We enrolled twenty young (20–30 yr) and twenty elderly (60–70 yr) healthy subjects and measured their LV and LA volumes by cardiac magnetic resonance imaging at rest and during dobutamine and glycopyrrolate stress. We identified LA minimum, maximum, and middiastolic volumes and the volume before atrial contraction. LA emptying volumes were calculated as LA passive and active emptying volumes and LA conduit volume. We also calculated LV peak filling rates (LVPFRs). Both at rest and during PS, LA maximum and minimum volumes were similar in the groups, whereas middiastolic volume was higher in the elderly. During PS, a marked decrease in LA passive emptying function and a corresponding increase in LA active emptying function were seen in the elderly but not in the young. At rest, LVPFR was lower in the elderly, and during PS this difference was augmented. The aging heart has reduced LVPFR, which is reflected in reduced LA passive and compensatory increased LA active volumetric contribution to LV stroke volume. These age-related differences are evident at rest and highly augmented during both dobutamine and glycopyrrolate stress.
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Affiliation(s)
- Kiril A. Ahtarovski
- Department of Cardiology, The Heart Centre, Rigshospitalet, Copenhagen University Hospital and Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Kasper K. Iversen
- Department of Cardiology, The Heart Centre, Rigshospitalet, Copenhagen University Hospital and Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jacob T. Lønborg
- Department of Cardiology, The Heart Centre, Rigshospitalet, Copenhagen University Hospital and Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Per L. Madsen
- Department of Cardiology, The Heart Centre, Rigshospitalet, Copenhagen University Hospital and Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Thomas Engstrøm
- Department of Cardiology, The Heart Centre, Rigshospitalet, Copenhagen University Hospital and Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Niels Vejlstrup
- Department of Cardiology, The Heart Centre, Rigshospitalet, Copenhagen University Hospital and Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
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15
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Grandi E, Workman AJ, Pandit SV. Altered Excitation-Contraction Coupling in Human Chronic Atrial Fibrillation. J Atr Fibrillation 2012; 4:495. [PMID: 28496736 DOI: 10.4022/jafib.495] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2011] [Revised: 02/10/2012] [Accepted: 03/19/2012] [Indexed: 12/19/2022]
Abstract
This review focuses on the (mal)adaptive processes in atrial excitation-contraction coupling occurring in patients with chronic atrial fibrillation. Cellular remodeling includes shortening of the atrial action potential duration and effective refractory period, depressed intracellular Ca2+ transient, and reduced myocyte contractility. Here we summarize the current knowledge of the ionic bases underlying these changes. Understanding the molecular mechanisms of excitation-contraction-coupling remodeling in the fibrillating human atria is important to identify new potential targets for AF therapy.
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Affiliation(s)
- Eleonora Grandi
- Department of Pharmacology, University of California at Davis, Davis, CA, USA
| | - Antony J Workman
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, UK
| | - Sandeep V Pandit
- Center for Arrhythmia Research, University of Michigan, Ann Arbor, MI, USA
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16
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Mattera GG, Vanoli E, Martinez V, Luciani M, Falco T, Borsini F. Adrenergic effects on force-frequency relationship: a pivotal role for the cardiac intrinsic systems. Acta Physiol (Oxf) 2011; 202:141-9. [PMID: 21338472 DOI: 10.1111/j.1748-1716.2011.02266.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
AIM The force-frequency relationship (F-FR) is an important intrinsic regulatory mechanism of cardiac contractility. The involvement of autonomic nervous system in this physiological aspect of cardiac control remains unclear. The aim of the study was to evaluate the role of extrinsic and intrinsic cardiac adrenergic innervations on the heart rate (HR)-related positive inotropic response. METHODS Twenty-four dogs were anesthetized and acutely instrumented to monitor and record ECG, systemic and left ventricular pressures and derivatives, and to pace the heart at 130, 150, 170, 190 and 210 bpm, in order to construct the F-FR curve. Animals were randomly assigned to four groups (n = 6 each): vehicle (V), ganglion-blocked (G-B), β-blocked (β-B) and ganglion-blocked plus β-blocked (G-B + β-B). RESULTS Vehicle treated animals presented the classical F-FR. In the β-B group F-FR was blunted, but never fully suppressed. The G-B treated animals showed a bell-shape response curve of the induced inotropic effect with the zenith at 170 bpm: the first part of the curve resembling the control one, followed by a rapid decline toward baseline value. The co-administration of G-B and β-B agents reversed the contractile response to HR rise with a curve resembling the negative F-FR curve observed in the failing heart. CONCLUSION The F-FR appeared to be constituted by two consecutive mechanisms: first depolarization-rate dependent, and a second catecholamine-dependent. The natural consequence of these observations is that the full expression of F-FR needs an intact adrenergic system.
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Affiliation(s)
- G G Mattera
- Research and Development Sigma-Tau S.p.A., Pomezia, Italy.
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17
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Schmidt MR, White PA, Khambadkone S, Gross GJ, Bøtker HE, Vogel M, Hjortdal VE, Sørensen KE, Redington AN. The neonatal but not the mature heart adapts to acute tachycardia by beneficial modification of the force-frequency relationship. Pediatr Cardiol 2011; 32:562-7. [PMID: 21394656 DOI: 10.1007/s00246-011-9899-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2008] [Accepted: 01/31/2011] [Indexed: 10/18/2022]
Abstract
The force-frequency relationship (FFR) reflects alterations in intracellular calcium cycling during changing heart rate (HR). Tachycardia-induced heart failure is associated with depletion of intracellular calcium. We hypothesized (1) that the relative resistance to tachycardia-induced heart failure seen in neonatal pigs is related to differences in calcium cycling, resulting in different FFR responses and (2) that pretreatment with digoxin to increase intracellular calcium would modifies these changes. LV +dP/dt was measured during incremental right atrial pacing in 16 neonatal and 14 adult pigs. FFR was measured as the change in +dP/dt as HR was increased. Animals were randomized to control or intravenous bolus digoxin (n = 8 neonate pigs in the 0.05 mg/kg group and n = 7 adult pigs in the 0.025 mg/kg group) and paced for 90 min at 25 bpm greater than the rate of peak +dP/dt. Repeat FFR was then obtained. The postpacing FFR in neonatal control pigs shifted rightward, with peak force occurring 30 bpm greater than baseline (P < 0.03). There was no vertical shift; thus, force at 150 bpm decreased (P < 0.03) and force at 300 beats/min increased (P < 0.08). In adult control pigs, FFR shifted downward (P < 0.01), with decreased force generation at all HRs. In both neonates and adult pigs, digoxin increased +dP/dt at all HRs; however, in neonate pigs digoxin decreased the contractile reserve by abrogation of the rightward shift of FFR. An adaptive response to tachycardia in the neonate pig leads to improved force generation at greater HRs. Conversely, the response of the mature pig heart is maladaptive with decreased force generation. Pretreatment with digoxin modifies these responses.
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Affiliation(s)
- M R Schmidt
- Aarhus University Hospital, Skejby Sygehus, Aarhus, Denmark.
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19
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Solzbach U, Kitterer HR, Haas H. Reversible congestive heart failure in severe hypocalcemia. Herz 2010; 35:507-10. [DOI: 10.1007/s00059-010-3374-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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20
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Chen X, Sala-Mercado JA, Hammond RL, Ichinose M, Soltani S, Mukkamala R, O'Leary DS. Dynamic control of maximal ventricular elastance via the baroreflex and force-frequency relation in awake dogs before and after pacing-induced heart failure. Am J Physiol Heart Circ Physiol 2010; 299:H62-9. [PMID: 20435845 PMCID: PMC2904132 DOI: 10.1152/ajpheart.00922.2009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2009] [Accepted: 04/30/2010] [Indexed: 11/22/2022]
Abstract
We investigated to what extent maximal ventricular elastance (E(max)) is dynamically controlled by the arterial baroreflex and force-frequency relation in conscious dogs and to what extent these mechanisms are attenuated after the induction of heart failure (HF). We mathematically analyzed spontaneous beat-to-beat hemodynamic variability. First, we estimated E(max) for each beat during a baseline period using the ventricular unstressed volume determined with the traditional multiple beat method during vena cava occlusion. We then jointly identified the transfer functions (system gain value and time delay per frequency) relating beat-to-beat fluctuations in arterial blood pressure (ABP) to E(max) (ABP-->E(max)) and beat-to-beat fluctuations in heart rate (HR) to E(max) (HR-->E(max)) to characterize the dynamic properties of the arterial baroreflex and force-frequency relation, respectively. During the control condition, the ABP-->E(max) transfer function revealed that ABP perturbations caused opposite direction E(max) changes with a gain value of -0.023 +/- 0.012 ml(-1), whereas the HR-->E(max) transfer function indicated that HR alterations caused same direction E(max) changes with a gain value of 0.013 +/- 0.005 mmHg.ml(-1).(beats/min)(-1). Both transfer functions behaved as low-pass filters. However, the ABP-->E(max) transfer function was more sluggish than the HR-->E(max) transfer function with overall time constants (indicator of full system response time to a sudden input change) of 11.2 +/- 2.8 and 1.7 +/- 0.5 s (P < 0.05), respectively. During the HF condition, the ABP-->E(max) and HR-->E(max) transfer functions were markedly depressed with gain values reduced to -0.0002 +/- 0.007 ml(-1) and -0.001 +/- 0.004 mmHg.ml(-1).(beats/min)(-1) (P < 0.1). E(max) is rapidly and significantly controlled at rest, but this modulation is virtually abolished in HF.
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Affiliation(s)
- Xiaoxiao Chen
- Department of Electrical and Computer Engineering, Michigan State University, East Lansing, MI, USA
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21
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There goes the neighborhood: pathological alterations in T-tubule morphology and consequences for cardiomyocyte Ca2+ handling. J Biomed Biotechnol 2010; 2010:503906. [PMID: 20396394 PMCID: PMC2852607 DOI: 10.1155/2010/503906] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2009] [Accepted: 01/15/2010] [Indexed: 12/19/2022] Open
Abstract
T-tubules are invaginations of the cardiomyocyte membrane into the cell interior which form a tortuous network. T-tubules provide proximity between the electrically excitable cell membrane and the sarcoplasmic reticulum, the main intracellular Ca2+ store. Tight coupling between the rapidly spreading action potential and Ca2+ release units in the SR membrane ensures synchronous Ca2+ release throughout the cardiomyocyte. This is a requirement for rapid and powerful contraction. In recent years, it has become clear that T-tubule structure and composition are altered in several pathological states which may importantly contribute to contractile defects in these conditions. In this review, we describe the “neighborhood” of proteins in the dyadic cleft which locally controls cardiomyocyte Ca2+ homeostasis and how alterations in T-tubule structure and composition may alter this neighborhood during heart failure, atrial fibrillation, and diabetic cardiomyopathy. Based on this evidence, we propose that T-tubules have the potential to serve as novel therapeutic targets.
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Workman AJ. Cardiac adrenergic control and atrial fibrillation. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2010; 381:235-49. [PMID: 19960186 PMCID: PMC2855383 DOI: 10.1007/s00210-009-0474-0] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2009] [Accepted: 11/08/2009] [Indexed: 10/20/2022]
Abstract
Atrial fibrillation (AF) is the most common cardiac arrhythmia, and it causes substantial mortality. The autonomic nervous system, and particularly the adrenergic/cholinergic balance, has a profound influence on the occurrence of AF. Adrenergic stimulation from catecholamines can cause AF in patients. In human atrium, catecholamines can affect each of the electrophysiological mechanisms of AF initiation and/or maintenance. Catecholamines may produce membrane potential oscillations characteristic of afterdepolarisations, by increasing Ca(2+) current, [Ca(2+)](i) and consequent Na(+)-Ca(2+) exchange, and may also enhance automaticity. Catecholamines might affect reentry, by altering excitability or conduction, rather than action potential terminal repolarisation or refractory period. However, which arrhythmia mechanisms predominate is unclear, and likely depends on cardiac pathology and adrenergic tone. Heart failure (HF), a major cause of AF, causes adrenergic activation and adaptational changes, remodelling, of atrial electrophysiology, Ca(2+) homeostasis, and adrenergic responses. Chronic AF also remodels these, but differently to HF. Myocardial infarction and AF cause neural remodelling that also may promote AF. beta-Adrenoceptor antagonists (beta-blockers) are used in the treatment of AF, mainly to control the ventricular rate, by slowing atrioventricular conduction. beta-Blockers also reduce the incidence of AF, particularly in HF or after cardiac surgery, when adrenergic tone is high. Furthermore, the chronic treatment of patients with beta-blockers remodels the atria, with a potentially antiarrhythmic increase in the refractory period. Therefore, the suppression of AF by beta-blocker treatment may involve an attenuation of arrhythmic activity that is caused by increased [Ca(2+)](i), coupled with effects of adaptation to the treatment. An improved understanding of the involvement of the adrenergic system and its control in basic mechanisms of AF under differing cardiac pathologies might lead to better treatments.
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Affiliation(s)
- Antony J Workman
- British Heart Foundation Glasgow Cardiovascular Research Centre, Division of Cardiovascular and Medical Sciences, Faculty of Medicine, University of Glasgow, 126 University Place, Glasgow, G12 8TA, UK.
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Fauconnier J, Pasquié JL, Bideaux P, Lacampagne A, Richard S. Cardiomyocytes hypertrophic status after myocardial infarction determines distinct types of arrhythmia: role of the ryanodine receptor. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2010; 103:71-80. [PMID: 20109482 DOI: 10.1016/j.pbiomolbio.2010.01.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2009] [Accepted: 01/08/2010] [Indexed: 11/20/2022]
Abstract
The mechanisms responsible for sudden cardiac death in heart failure (HF) are unclear. We investigated early and delayed afterdepolarizations (EADs, DADs) in HF. Cardiomyocytes were enzymatically isolated from the right ventricle (RV) and the septum of rats 8 weeks after myocardial infarction (MI) and sham-operated animals. Membrane capacitance, action potentials (AP) and ionic currents were measured by whole-cell patch-clamp. The [Ca(2+)](i) transients and Ca(2+) sparks were recorded with Fluo-4 during fluorescence measurements. Arrhythmia was triggered in 40% of MI cells (not in sham) using trains of 5 stimulations at 2.0 Hz. EADs and DADs occurred in distinct cell populations both in the RV and the septum. EADs occurred in normal-sized PMI cells (<230 pF), whereas DADs occurred in hypertrophic PMI cells (>230 pF). All cells exhibited prolonged APs due to reduced I(to) current. However, additional modifications in Ca(2+)-dependent ionic currents occurred in hypertrophic cells: a decrease in the inward rectifier K(+) current I(K1), and a slowing of L-type Ca(2+) current inactivation which was responsible for the lack of adaptation of APs to abrupt changes in the pacing rate. The occurrence of spontaneous Ca(2+) sparks, reflecting ryanodine receptor (RyR2) diastolic activity, increased with hypertrophy. The [Ca(2+)](i) transient amplitude, sarcoplasmic reticulum (SR) Ca(2+) load and Ca(2+) sparks amplitude were all inversely correlated with cell size. We conclude that the trophic status of cardiomyocytes determines the type of cellular arrhythmia in MI rats, based on differential electrophysiological remodeling which may reflect early-mild and late-severe or differential modifications in the RyR2 function.
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Affiliation(s)
- Jérémy Fauconnier
- INSERM U637, Université Montpellier1, Department of Cardiovascular Physiopathology, 371 avenue du Doyen Gaston Giraud, F34295 Montpellier Cedex 5, France
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GEMIGNANI VINCENZO, BIANCHINI ELISABETTA, FAITA FRANCESCO, LIONETTI VINCENZO, CAMPAN MANUELA, RECCHIA FABIOANASTASIO, PICANO EUGENIO, BOMBARDINI TONINO. Transthoracic Sensor for Noninvasive Assessment of Left Ventricular Contractility: Validation in A Minipig Model of Chronic Heart Failure. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2010; 33:795-803. [DOI: 10.1111/j.1540-8159.2009.02684.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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25
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Wang Y, Hill JA. Electrophysiological remodeling in heart failure. J Mol Cell Cardiol 2010; 48:619-32. [PMID: 20096285 DOI: 10.1016/j.yjmcc.2010.01.009] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2008] [Revised: 01/11/2010] [Accepted: 01/12/2010] [Indexed: 11/25/2022]
Abstract
Heart failure affects nearly 6 million Americans, with a half-million new cases emerging each year. Whereas up to 50% of heart failure patients die of arrhythmia, the diverse mechanisms underlying heart failure-associated arrhythmia are poorly understood. As a consequence, effectiveness of antiarrhythmic pharmacotherapy remains elusive. Here, we review recent advances in our understanding of heart failure-associated molecular events impacting the electrical function of the myocardium. We approach this from an anatomical standpoint, summarizing recent insights gleaned from pre-clinical models and discussing their relevance to human heart failure.
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Affiliation(s)
- Yanggan Wang
- Department of Pediatrics, Emory University, Atlanta, GA, USA.
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Karliova I, Denk K, Hakami L, Bonz A, Peivandi A, Sonnenberg K, Vahl C. Positiv inotroper Effekt von Ivabradin am atrialen Myokard des Menschen. ZEITSCHRIFT FUR HERZ THORAX UND GEFASSCHIRURGIE 2009. [DOI: 10.1007/s00398-009-0730-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Parilak LD, Taylor DG, Song Y, Burkart T, Shryock JC, Curtis AB, Knot HJ. Contribution of frequency-augmented inward Ca2+ current to myocardial contractility. Can J Physiol Pharmacol 2009; 87:69-75. [DOI: 10.1139/y08-087] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The sarcoplasmic reticular Ca2+ pump (SERCA) is thought to be the primary determinant of heart rate-dependent increases in myocardial contractile [Ca2+]i and force (force–frequency relationship (FFR)), an important mechanism to increase cardiac output. This report demonstrates a rate-dependent role for inward Ca2+ current (ICa) in the human and rat FFR. Human action potential plateau height increased linearly with contractility when heart rate increased in vivo, as measured by monophasic action potential catheter and echocardiography. Rat rate-dependent developed force and cytosolic [Ca2+]i transients were quantified in isolated left ventricular papillary muscles, and ICa and action potential duration in cardiomyocytes. ICa and SERCA measurements better reflected [Ca2+]i and force transients than SERCA activity alone. These data support a direct and (or) indirect contribution to myocardial contractility by ICa at heart rates from approximately 1 to 3–4 Hz (60 to 180–240 bpm) in tandem with SERCA to sustain the typical ‘bell shape’ of the FFR across species.
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Affiliation(s)
- Leonard D. Parilak
- Departments of Pharmacology and Therapeutics, Division of Cardiovascular Medicine, University of Florida, Gainesville, FL 32610, USA
- Department of Medicine, Division of Cardiovascular Medicine, University of Florida, Gainesville, Florida, USA
| | - David G. Taylor
- Departments of Pharmacology and Therapeutics, Division of Cardiovascular Medicine, University of Florida, Gainesville, FL 32610, USA
- Department of Medicine, Division of Cardiovascular Medicine, University of Florida, Gainesville, Florida, USA
| | - Yejia Song
- Departments of Pharmacology and Therapeutics, Division of Cardiovascular Medicine, University of Florida, Gainesville, FL 32610, USA
- Department of Medicine, Division of Cardiovascular Medicine, University of Florida, Gainesville, Florida, USA
| | - Thomas Burkart
- Departments of Pharmacology and Therapeutics, Division of Cardiovascular Medicine, University of Florida, Gainesville, FL 32610, USA
- Department of Medicine, Division of Cardiovascular Medicine, University of Florida, Gainesville, Florida, USA
| | - John C. Shryock
- Departments of Pharmacology and Therapeutics, Division of Cardiovascular Medicine, University of Florida, Gainesville, FL 32610, USA
- Department of Medicine, Division of Cardiovascular Medicine, University of Florida, Gainesville, Florida, USA
| | - Anne B. Curtis
- Departments of Pharmacology and Therapeutics, Division of Cardiovascular Medicine, University of Florida, Gainesville, FL 32610, USA
- Department of Medicine, Division of Cardiovascular Medicine, University of Florida, Gainesville, Florida, USA
| | - Harm J. Knot
- Departments of Pharmacology and Therapeutics, Division of Cardiovascular Medicine, University of Florida, Gainesville, FL 32610, USA
- Department of Medicine, Division of Cardiovascular Medicine, University of Florida, Gainesville, Florida, USA
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Yano M, Yamamoto T, Kobayashi S, Ikeda Y, Matsuzaki M. Defective Ca2+ cycling as a key pathogenic mechanism of heart failure. Circ J 2008; 72 Suppl A:A22-30. [PMID: 18772523 DOI: 10.1253/circj.cj-08-0070] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Structural and functional alterations in the Ca(2+) regulatory proteins present in the sarcoplasmic reticulum (SR) have recently been shown to play a crucial role in the pathogenesis of heart failure (HF), and lethal arrhythmia as well. Chronic activation of the sympathetic nervous system induces abnormalities in both the function and structure of these proteins. For instance, the diastolic Ca(2+) leak through the SR Ca(2+) release channel (ryanodine receptor) reduces the SR Ca(2+) content, inducing contractile dysfunction. Moreover, the Ca(2+) leak provides a substrate for delayed after depolarization that leads to lethal arrhythmia. There is a considerable body of evidence regarding the role of Ca(2+) cycling abnormality in HF.
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Affiliation(s)
- Masafumi Yano
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, Ube, Japan.
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Chou CC, Nguyen BL, Tan AY, Chang PC, Lee HL, Lin FC, Yeh SJ, Fishbein MC, Lin SF, Wu D, Wen MS, Chen PS. Intracellular calcium dynamics and acetylcholine-induced triggered activity in the pulmonary veins of dogs with pacing-induced heart failure. Heart Rhythm 2008; 5:1170-7. [PMID: 18554987 DOI: 10.1016/j.hrthm.2008.04.009] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/24/2007] [Accepted: 04/09/2008] [Indexed: 11/19/2022]
Abstract
BACKGROUND Heart failure increases autonomic nerve activities and changes intracellular calcium (Ca(i)) dynamics. OBJECTIVE The purpose of this study was to investigate the hypothesis that abnormal Ca(i) dynamics are responsible for triggered activity in the pulmonary veins (PVs) during acetylcholine infusion in a canine model of heart failure. METHODS Simultaneous optical mapping of Ca(i) and membrane potential was performed in isolated Langendorff-perfused PV-left atrial (LA) preparations from nine dogs with ventricular pacing-induced heart failure. Mapping was performed at baseline, during acetylcholine (1 micromol/L) infusion (N = 9), and during thapsigargin and ryanodine infusion (N = 6). RESULTS Acetylcholine abbreviated the action potential. In four tissues, long pauses were followed by elevated diastolic Ca(i), late phase 3 early afterdepolarizations, and atrial fibrillation (AF). The incidence of PV focal discharges during AF was increased by acetylcholine from 2.4 +/- 0.6 beats/s (N = 4) to 6.5 +/- 2.2 beats/s (N = 8; P = .003). PV focal discharge and PV-LA microreentry coexisted in 6 of 9 preparations. The spatial distribution of dominant frequency demonstrated a focal source pattern, with the highest dominant frequency areas colocalized with PV focal discharge sites in 35 (95%) of 37 cholinergic AF episodes (N = 8). Thapsigargin and ryanodine infusion eliminated focal discharges in 6 of 6 preparations and suppressed the inducibility of AF in 4 of 6 preparations. PVs with focal discharge have higher densities of parasympathetic nerves than do PVs without focal discharges (P = .01), and periodic acid-Schiff (PAS)-positive cells were present at the focal discharge sites. CONCLUSION Ca(i) dynamics are important in promoting triggered activity during acetylcholine infusion in PVs from pacing-induced heart failure. PV focal discharge sites have PAS-positive cells and high densities of parasympathetic nerves.
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Affiliation(s)
- Chung-Chuan Chou
- Department of Medicine, Second Section of Cardiology, Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Taoyuan, Taiwan
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Shin SY, Choo SM, Woo SH, Cho KH. Cardiac Systems Biology and Parameter Sensitivity Analysis: Intracellular Ca2+ Regulatory Mechanisms in Mouse Ventricular Myocytes. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2008; 110:25-45. [DOI: 10.1007/10_2007_093] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
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Bombardini T, Gemignani V, Bianchini E, Venneri L, Petersen C, Pasanisi E, Pratali L, Pianelli M, Faita F, Giannoni M, Picano E. Cardiac reflections and natural vibrations: force-frequency relation recording system in the stress echo lab. Cardiovasc Ultrasound 2007; 5:42. [PMID: 18031588 PMCID: PMC2221800 DOI: 10.1186/1476-7120-5-42] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2007] [Accepted: 11/22/2007] [Indexed: 11/18/2022] Open
Abstract
Background The inherent ability of ventricular myocardium to increase its force of contraction in response to an increase in contraction frequency is known as the cardiac force-frequency relation (FFR). This relation can be easily obtained in the stress echo lab, where the force is computed as the systolic pressure/end-systolic volume index ratio, and measured for increasing heart rates during stress. Ideally, the noninvasive, imaging independent, objective assessment of FFR would greatly enhance its practical appeal. Objectives 1 – To evaluate the feasibility of the cardiac force measurement by a precordial cutaneous sensor. 2 – To build the curve of force variation as a function of the heart rate. 3 – To compare the standard stress echo results vs. this sensor operator-independent built FFR. Methods The transcutaneous force sensor was positioned in the precordial region in 88 consecutive patients referred for exercise, dipyridamole, or pacing stress. The force was measured as the myocardial vibrations amplitude in the isovolumic contraction period. FFR was computed as the curve of force variation as a function of heart rate. Standard echocardiographic FFR measurements were performed. Results A consistent FFR was obtained in all patients. Both the sensor built and the echo built FFR identifiy pts with normal or abnormal contractile reserve. The best cut-off value of the sensor built FFR was 15.5 g * 10-3 (Sensitivity = 0.85, Specificity = 0.77). Sensor built FFR slope and shape mirror pressure/volume relation during stress. This approach is extendable to daily physiological exercise and could be potentially attractive in home monitoring systems.
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Altamirano J, Bers DM. Effect of intracellular Ca2+ and action potential duration on L-type Ca2+ channel inactivation and recovery from inactivation in rabbit cardiac myocytes. Am J Physiol Heart Circ Physiol 2007; 293:H563-73. [PMID: 17400724 DOI: 10.1152/ajpheart.00469.2006] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ca2+ current ( ICa) recovery from inactivation is necessary for normal cardiac excitation-contraction coupling. In normal hearts, increased stimulation frequency increases force, but in heart failure (HF) this force-frequency relationship (FFR) is often flattened or reversed. Although reduced sarcoplasmic reticulum Ca2+-ATPase function may be involved, decreased ICa availability may also contribute. Longer action potential duration (APD), slower intracellular Ca2+ concentration ([Ca2+]i) decline, and higher diastolic [Ca2+]i in HF could all slow ICa recovery from inactivation, thereby decreasing ICa availability. We measured the effect of different diastolic [Ca2+]i on ICa inactivation and recovery from inactivation in rabbit cardiac myocytes. Both ICa and Ba2+ current ( IBa) were measured. ICa decay was accelerated only at high diastolic [Ca2+]i (600 nM). IBa inactivation was slower but insensitive to [Ca2+]i. Membrane potential dependence of ICa or IBa availability was not affected by [Ca2+]i <600 nM. Recovery from inactivation was slowed by both depolarization and high [Ca2+]i. We also used perforated patch with action potential (AP)-clamp and normal Ca2+ transients, using various APDs as conditioning pulses for different frequencies (and to simulate HF APD). Recovery of ICa following longer APD was increasingly incomplete, decreasing ICa availability. Trains of long APs caused a larger ICa decrease than short APD at the same frequency. This effect on ICa availability was exacerbated by slowing twitch [Ca2+]i decline by ∼50%. We conclude that long APD and slower [Ca2+]i decline lead to cumulative inactivation limiting ICa at high heart rates and might contribute to the negative FFR in HF, independent of altered Ca2+ channel properties.
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Affiliation(s)
- Julio Altamirano
- Department of Physiology, Stritch School of Medicine, Loyola University Chicago, 2160 South First Ave., Maywood, IL 60153, USA
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Transient T wave Changes Concerning Arrhythmia. J Arrhythm 2007. [DOI: 10.1016/s1880-4276(07)80022-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
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Brixius K, Frank KF, Bölck B, Hoyer F, Schwinger RHG. [Reverse remodeling of the intracellular Ca(2+)-homeostasis: new concepts of pathophysiology and therapy of heart failure]. Wien Med Wochenschr 2006; 156:209-15. [PMID: 16823538 DOI: 10.1007/s10354-005-0239-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2005] [Accepted: 10/21/2005] [Indexed: 01/08/2023]
Abstract
Cardiac contraction is dependent on a rapid alteration of the intracellular Ca(2+) concentration, especially the Ca(2+) released during systole. In end-stage heart failure, cardiac contractility is depressed due to alterations in the structure and function of proteins or protein complexes. Over recent years, new insights have been obtained regarding the regulation of the intracellular Ca(2+) homeostasis and its pathophysiological alteration in end-stage heart failure. This review focuses on the mechanisms involved in the release of Ca(2+) from the sarcoplasmic reticulum (SR) during systole via the ryanodine receptors and the Ca(2+)-uptake into the SR by the sarcoplasmic reticulum Ca(2+)-ATPase (SERCA 2a). In addition, new therapeutic options will be introduced which may be of importance for the treatment of heart failure patients.
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Affiliation(s)
- Klara Brixius
- Labor für Herzmuskelphysiologie und Molekulare Kardiologie, Klinik III für Innere Medizin, Köln
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Bombardini T. Myocardial contractility in the echo lab: molecular, cellular and pathophysiological basis. Cardiovasc Ultrasound 2005; 3:27. [PMID: 16150150 PMCID: PMC1242240 DOI: 10.1186/1476-7120-3-27] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2005] [Accepted: 09/08/2005] [Indexed: 12/25/2022] Open
Abstract
In the standard accepted concept, contractility is the intrinsic ability of heart muscle to generate force and to shorten, independently of changes in the preload or afterload with fixed heart rates. At molecular level the crux of the contractile process lies in the changing concentrations of Ca2+ ions in the myocardial cytosol. Ca2+ ions enter through the calcium channel that opens in response to the wave of depolarization that travels along the sarcolemma. These Ca2+ ions "trigger" the release of more calcium from the sarcoplasmic reticulum (SR) and thereby initiate a contraction-relaxation cycle. In the past, several attempts were made to transfer the pure physiological concept of contractility, expressed in the isolated myocardial fiber by the maximal velocity of contraction of unloaded muscle fiber (Vmax), to the in vivo beating heart. Suga and Sagawa achieved this aim by measuring pressure/volume loops in the intact heart: during a positive inotropic intervention, the pressure volume loop reflects a smaller end-systolic volume and a higher end-systolic pressure, so that the slope of the pressure volume relationship moves upward and to the left. The pressure volume relationship is the most reliable index for assessing myocardial contractility in the intact circulation and is almost insensitive to changes in preload and after load. This is widely used in animal studies and occasionally clinically. The limit of the pressure volume relationship is that it fails to take into account the frequency-dependent regulation of contractility: the frequency-dependent control of transmembrane Ca2+ entry via voltage-gated Ca2+ channels provides cardiac cells with a highly sophisticated short-term system for the regulation of intracellular Ca2+ homeostasis. An increased stimulation rate increases the force of contraction: the explanation is repetitive Ca2+ entry with each depolarization and, hence, an accumulation of cytosolic calcium. As the heart fails, there is a change in the gene expression from the normal adult pattern to that of fetal life with an inversion of the normal positive slope of the force-frequency relation: systolic calcium release and diastolic calcium reuptake process is lowered at the basal state and, instead of accelerating for increasing heart rates, slows down. Since the force-frequency relation uncovers initial alteration of contractility, as an intermediate step between normal and abnormal contractility at rest, a practical index to measure it is mandatory. Measuring end-systolic elastance for increasing heart rates is impractical: increasing heart rates with atrial pacing has to be adjunct to the left ventricular conductance catheter, to the left ventricular pressure catheter, to the vena cava balloon, and to afterload changes. Furthermore, a noninvasive index is needed. Noninvasive measurement of the pressure/volume ratio for increasing heart rates during stress in the echo lab could be the practical answer to this new clinical demand in the current years of a dramatic increase in the number of heart failure patients.
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Affiliation(s)
- Tonino Bombardini
- Department of Echocardiography, Institute of Clinical Physiology, National Council of Research, Pisa, Italy.
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Yano M, Yamamoto T, Ikemoto N, Matsuzaki M. Abnormal ryanodine receptor function in heart failure. Pharmacol Ther 2005; 107:377-91. [PMID: 15951021 DOI: 10.1016/j.pharmthera.2005.04.003] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2005] [Accepted: 04/13/2005] [Indexed: 11/16/2022]
Abstract
The abnormally regulated release of Ca2+ from an intracellular Ca2+ store, the sarcoplasmic reticulum (SR), is the mechanism underlying contractile and relaxation dysfunctions in heart failure (HF). According to recent reports, protein kinase A (PKA)-mediated hyperphosphorylation of ryanodine receptor (RyR) in the SR has been shown to cause the dissociation of FK506 binding protein (FKBP) 12.6 from the RyR in heart failure. This causes an abnormal Ca2+ leak through the Ca2+ channel located in the RyR, leading to an increase in the cytosolic Ca2+ during diastole, prolongation of the Ca2+ transient, and delayed/slowed diastolic Ca2+ re-uptake. More recently, a considerable number of disease-linked mutations in the RyR have been reported in patients with catecholaminergic polymorphic ventricular tachycardia (CPVT) or arrhythmogenic right ventricular dysplasia type 2. An analysis of the disposition of these mutation sites within well-defined domains of the RyR polypeptide chain has led to the new concept that interdomain interactions among these domains play a critical role in channel regulation, and an altered domain interaction causes channel dysfunction in the failing heart. The knowledge gained from the recent literature concerning the critical proteins and the changes in their properties under pathological conditions has brought us to a better position to develop new pharmacological or genetic strategies for the treatment of heart failure or cardiac arrhythmia. A considerable body of evidence reviewed here indicates that abnormal RyR function plays an important role in the pathogenesis of heart failure. This review also covers some controversial issues in the literature concerning the involvement of phosphorylation and FKBP12.6.
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Affiliation(s)
- Masafumi Yano
- Department of Medical Bioregulation, Division of Cardiovascular Medicine, Yamaguchi University School of Medicine, Yamaguchi, Japan.
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Grosu A, Bombardini T, Senni M, Duino V, Gori M, Picano E. End-systolic pressure/volume relationship during dobutamine stress echo: a prognostically useful non-invasive index of left ventricular contractility. Eur Heart J 2005; 26:2404-12. [PMID: 16105848 DOI: 10.1093/eurheartj/ehi444] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
AIMS Left ventricular end-systolic pressure-volume relationship (PVR) provides a robust, relatively load-insensitive evaluation of contractility and can be assessed non-invasively during exercise echo. Dobutamine might provide an exercise-independent alternative approach to assess inotropic reserve. The feasibility of a non-invasive estimation of PVR during dobutamine stress in the echo lab and its relationship with subsequent clinical events was assessed. METHODS AND RESULTS We enrolled 137 consecutive patients referred for dobutamine stress echo. To build the PVR, the force was determined at different heart rate increments during stepwise dobutamine infusion as the ratio of the systolic pressure/end-systolic volume index. The PVR at increasing heart rate was flat-biphasic in 65 and up-sloping in 72 patients: 42 patients underwent surgery and 95 patients were treated medically (median follow-up, 18 months; interquartile range, 12-24). Events occurred in 18 patients (death in eight, acute heart failure in 10); a flat-biphasic PVR was independent predictor of events (RR=10.16, P<0.01). CONCLUSION PVR is feasible during dobutamine stress. This index of global contractility is reasonably simple, does not affect the imaging time, and only minimally prolongs the off-line analysis time. It allows unmasking quite different, and heterogeneous, contractility reserve patterns underlying a given ejection fraction at rest. The best survival is observed in patients with up-sloping PVR, whereas flat-biphasic pattern is a strong predictor of cardiac events.
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Affiliation(s)
- Aurelia Grosu
- Department of Cardiovascular Medicine and Internal Medicine, Ospedali Riuniti, Bergamo, Italy
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Bombardini T, Agrusta M, Natsvlishvili N, Solimene F, Pap R, Coltorti F, Varga A, Mottola G, Picano E. Noninvasive assessment of left ventricular contractility by pacemaker stress echocardiography. Eur J Heart Fail 2005; 7:173-81. [PMID: 15701463 DOI: 10.1016/j.ejheart.2004.04.019] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2003] [Revised: 03/23/2004] [Accepted: 04/22/2004] [Indexed: 10/26/2022] Open
Abstract
BACKGROUND Estimating contractility of the left ventricle with noninvasive techniques is an important yet elusive goal. Positive inotropic interventions are mirrored by smaller end-systolic volumes and higher end-systolic pressures. An increased heart rate progressively increases the force of ventricular contraction (Bowditch treppe or staircase phenomenon). AIM To assess the feasibility of a noninvasive estimation of force-frequency relation (FFR) during pacing stress in the echo lab in patients with permanent pacemaker (PM). METHODS Transthoracic stress pacing echocardiography was performed in 26 patients with a permanent pacemaker (age 69+/-11 years; 21 men, 5 women). Seven patients had normal function at baseline and during stress ("normals"); eight had angiographically assessed coronary artery disease (three with and five without induced ischemia with stress echo); eleven patients had dilated cardiomyopathy (DC). To build the FFR, the force was determined at different steps as the ratio of the systolic pressure (SP, cuff sphygmomanometer)/end-systolic volume index (ESV, biplane Simpson rule/body surface area). Heart rate was determined from ECG. RESULTS The absolute value of the FFR slope was highest in controls and lowest in DC patients. A flat-downsloping FFR was found in 12/19 patients but not for normals (p<0.01). CONCLUSIONS Noninvasive pacemaker stress echocardiography (PASE) is a simple and efficient option to assess left ventricular (LV) contractility in patients with permanent pacemaker.
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Affiliation(s)
- Tonino Bombardini
- CNR, Institute of Clinical Physiology, Via Moruzzi 1, 56124 Pisa, Italy
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Yano M, Ikeda Y, Matsuzaki M. Altered intracellular Ca2+ handling in heart failure. J Clin Invest 2005; 115:556-64. [PMID: 15765137 PMCID: PMC1052007 DOI: 10.1172/jci24159] [Citation(s) in RCA: 144] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Structural and functional alterations in the Ca2+ regulatory proteins present in the sarcoplasmic reticulum have recently been shown to be strongly involved in the pathogenesis of heart failure. Chronic activation of the sympathetic nervous system or of the renin-angiotensin system induces abnormalities in both the function and structure of these proteins. We review here the considerable body of evidence that has accumulated to support the notion that such abnormalities contribute to a defectiveness of contractile performance and hence to the progression of heart failure.
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Affiliation(s)
- Masafumi Yano
- Department of Medical Bioregulation, Division of Cardiovascular Medicine, Yamaguchi University School of Medicine, Yamaguchi, Japan
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Mulieri LA, Tischler MD, Martin BJ, Leavitt BJ, Ittleman FP, Alpert NR, LeWinter MM. Regional differences in the force-frequency relation of human left ventricular myocardium in mitral regurgitation: implications for ventricular shape. Am J Physiol Heart Circ Physiol 2005; 288:H2185-91. [PMID: 15637116 DOI: 10.1152/ajpheart.00905.2003] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Sphericalization of the left ventricular (LV) chamber shape in patients with mitral regurgitation (MR) contributes to increased LV wall stress and energy consumption. On the basis of previous observations, we hypothesized the existence of regional differences in the force-frequency relation (FFR) within the LV that may contribute to its shape. Accordingly, in the present study, we assessed regional variation in the FFR in patients undergoing surgery for chronic, nonischemic MR with class II–III heart failure symptoms and related our findings to the in vivo LV shape. FFRs (steady-state isometric twitches, 0.2–3.4 Hz, 37°C) were evaluated in MR myocardium from the LV subepicardial free wall (MR-FW) and papillary muscle (MR-PM) and from the subepicardial free wall in coronary artery bypass graft patients with normal LV contraction patterns [nonfailing (NF)]. Ascending slope, optimal stimulation frequency, and maximal twitch tension of the FFR were depressed in MR-FW and MR-PM compared with NF ( P < 0.05). FFR depression was greater in MR-PM than in MR-FW. Between 107 and 134 beats/min, twitch tension became weaker in MR-PM, whereas it increased in MR-FW. Elevation of intracellular cAMP with forskolin eliminated FFR depression in MR-FW but not in MR-PM. MR-PM also had a 35% lower myosin heavy chain content and slowed twitch kinetics. In MR patients, the echocardiographic end-diastolic LV shape (end-diastolic eccentricity index = long axis/short axis) correlated with the ratio of ascending FFR slopes such that the end-diastolic eccentricity index increased 10% per 15% increase in slope ratio ( r = 0.88, P = 0.01). These regional differences in the frequency dependence of contractility between the free wall and papillary myocardium may contribute to changes in LV shape in MR as well as during exercise.
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Affiliation(s)
- Louis A Mulieri
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, Vermont 05405, USA
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Brette F, Leroy J, Le Guennec JY, Sallé L. Ca2+ currents in cardiac myocytes: Old story, new insights. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2005; 91:1-82. [PMID: 16503439 DOI: 10.1016/j.pbiomolbio.2005.01.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Calcium is a ubiquitous second messenger which plays key roles in numerous physiological functions. In cardiac myocytes, Ca2+ crosses the plasma membrane via specialized voltage-gated Ca2+ channels which have two main functions: (i) carrying depolarizing current by allowing positively charged Ca2+ ions to move into the cell; (ii) triggering Ca2+ release from the sarcoplasmic reticulum. Recently, it has been suggested than Ca2+ channels also participate in excitation-transcription coupling. The purpose of this review is to discuss the physiological roles of Ca2+ currents in cardiac myocytes. Next, we describe local regulation of Ca2+ channels by cyclic nucleotides. We also provide an overview of recent studies investigating the structure-function relationship of Ca2+ channels in cardiac myocytes using heterologous system expression and transgenic mice, with descriptions of the recently discovered Ca2+ channels alpha(1D) and alpha(1E). We finally discuss the potential involvement of Ca2+ currents in cardiac pathologies, such as diseases with autoimmune components, and cardiac remodeling.
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Affiliation(s)
- Fabien Brette
- School of Biomedical Sciences, University of Leeds, Worsley Building Leeds, LS2 9NQ, UK.
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Lechat P. [From ischaemia to heart failure: heart rate--actor or stamper?]. Therapie 2005; 59:485-9. [PMID: 15648299 DOI: 10.2515/therapie:2004084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The heart rate in sinus rhythm depends on If current-induced automaticity of sinus node cells. Such a current is activated by hyperpolarisation and is modulated by influences from sympathetic and para-sympathetic tones. There are established prognostic values for the baseline heart rate and its variability in coronary heart disease and heart failure. However, heart rate per se directly modulates myocardial oxygen consumption and cardiac contractility by interfering with the excitation-contraction coupling. The therapeutic implications of pharmacological modulation of the heart rate are important mainly for slowing the heart rate, as illustrated by the use of calcium antagonists in coronary heart disease and beta-blockers in both coronary heart disease and heart failure. The possibility of a direct action on sinusal automaticity by drugs such as ivabradine, an If channel blocker, reveals new therapeutic perspectives. Indeed, a benefit of combination therapy with these drugs and beta-blockers should be lower heart rate values than can be attained with maximally tolerated doses of beta-blockers.
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Affiliation(s)
- Philippe Lechat
- Service de Pharmacologie, Hôpital Pitié-Salpêtrière, Paris, France.
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Brixius K, Reuter H, Bloch W, Schwinger RHG. Altered hetero- and homeometric autoregulation in the terminally failing human heart. Eur J Heart Fail 2005; 7:29-35. [PMID: 15642528 DOI: 10.1016/j.ejheart.2004.03.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2003] [Revised: 03/05/2004] [Accepted: 03/10/2004] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVE AND METHODS To further investigate length-dependent force generation in human heart, nonfailing (donor hearts, NF) and terminally failing (heart transplants, dilated cardiomyopathy, DCM) left ventricular myocardium was studied under various preload (4-40 mN/mm2) or length conditions. In addition, morphological studies (van Giesson Trichrome staining, electron microscopy) were performed. RESULTS In NF, a biphasic increase in force of contraction (FOC) was observed after elevating the preload (4-40 mN/mm2): there was an immediate fast increase (FOCf,), followed by a slow increase over several minutes (FOCs), which was paralleled by an increase in the systolic fura-2 transient. In DCM, FOCf, FOCs and the systolic fura-2 transient were blunted and diastolic tension was increased at increasing muscle length. Only in NF, a stretched induced increase in diastolic fura-2 ratio was observed. In DCM, no obvious interstitial fibrosis and no difference in basement membrane structure and attachment were observed. CONCLUSIONS Since FOCf has been attributed to the Frank-Starling mechanism, whereas FOCs represents a length-dependent increase in the intracellular Ca2+-transient, the impaired length-dependent force generation in failing myocardium results from a dysregulation of both myofibrillar Ca2+-sensitivity as well as the intracellular Ca2+-homeostasis. Interstitial fibrosis may have only minor impact on force generation in human end-stage heart failure.
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Affiliation(s)
- Klara Brixius
- Laboratory of Muscle Research and Molecular Cardiology, Department of Internal Medicine III, Joseph-Stelzmann-Str. 9, 50924 Cologne (Lindenthal), Germany
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Abstract
Electrophysiological remodeling in heart failure (HF) is characterized by major changes in ion channel function and expression that alter the electrical phenotype and predispose to the development of lethal ventricular tachyarrhythmias. In this article, we provide a review of our current understanding of HF-induced ion channel dysfunction by highlighting changes in potassium and sodium currents, pumps, and exchangers as well as calcium handling proteins. We further relate these changes in ion channel function to abnormalities in impulse generation, conduction, and repolarization with a view towards identifying potentially novel targets for anti-arrhythmic therapy for this public health epidemic.
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Affiliation(s)
- Fadi G Akar
- Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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Palomeque J, Vila Petroff MG, Mattiazzi A. Pacing Staircase Phenomenon in the Heart: From Bodwitch to the XXI Century. Heart Lung Circ 2004; 13:410-20. [PMID: 16352227 DOI: 10.1016/j.hlc.2004.08.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The frequency of pacing is a fundamental physiological modulator of myocardial function. When the pacing rate increases there is normally an increase in contractility (a positive force-frequency relationship). However in small rodents, fish and end-stage failing myocardium, the force-frequency response has been found to be flat or even negative. The positive staircase is understood to be related with the increase in the intracellular Ca(2+) transient, mainly due to an enhanced sarcoplasmic reticulum Ca(2+) content at higher stimulation frequencies, resulting from an increase in Ca(2+) influx per unit time and reduced Ca(2+) efflux between beats. However, additional mechanisms, such as increased activity of Ca(2+)/calmodulin-dependent protein kinase or enhanced myofilament responsiveness to Ca(2+) may also play a role. Although an increase in contraction frequency has been shown to be associated with an increase in intracellular Na(+), several studies have shown a temporal dissociation between the increase in Na(i)(+) and the increase in force evoked by changes in pacing frequency. The way in which the Na(+)/Ca(2+) exchanger contributes to contraction frequency inotropy is still not well understood. The aim of this review is to examine the contribution of the fundamental components of cardiac excitation-contraction coupling to frequency inotropy in healthy and failing hearts.
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Affiliation(s)
- Julieta Palomeque
- Centro de Investigaciones Cardiovasculares, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, 60 y 120, La Plata 1900, Argentina
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Carmeliet E. Intracellular Ca2+ concentration and rate adaptation of the cardiac action potential. Cell Calcium 2004; 35:557-73. [PMID: 15110146 DOI: 10.1016/j.ceca.2004.01.010] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2003] [Accepted: 01/12/2004] [Indexed: 10/26/2022]
Abstract
Influx of Ca(2+) ions through the cardiac plasma membrane contributes to the shaping of the action potential plateau and acts as trigger for the release of Ca(2+) ions from the sarcoplasmic reticulum and the initiation of the contractile process. The increased intracellular Ca(2+) concentration feeds back on the channels and transporters in the plasma membrane and modulates the electrical activity. This interaction and its change with rate of pacing is the topic of this review, which is subdivided in three parts. In part I a description is given of different channels and transporters that carry Ca(2+) ions, or are activated-modulated by intracellular Ca(2+) ions. In part II an analysis is given of the changes in action potential duration and shape when stimuli are applied in the relative refractory period (electrical restitution) and when rate is suddenly increased and kept at the higher level until steady-state is obtained. A description of experimental findings in each case is followed by a discussion of possible mechanisms. Part III deals with physiopathological aspects of Ca(2+) handling and discusses recent information on hypertrophy, heart failure and atrial fibrillation.
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Affiliation(s)
- Edward Carmeliet
- Faculty of Medicine, C.E.H.A. University of Leuven, Gathuisberg, Leuven, Belgium.
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Ben-Abraham R, Shapira I, Szold A, Weinbroum AA. Attenuation of liver ischemia-reperfusion-induced atrial dysfunction by external pacing but not by isoproterenol. Can J Physiol Pharmacol 2004; 82:9-15. [PMID: 15052300 DOI: 10.1139/y03-125] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Remote ischemia–reperfusion detrimentally affects myocardial function by initially interfering with the rate of contraction. We investigated the usefulness of isoproterenol versus external electrical pacing in attenuating secondary functional damage of isolated Wistar rat atria. Atrial strips (n = 10/group) were bathed within oxygenated Krebs–Henseleit solution that exited from isolated livers that had been either perfused normally (controls) or underwent no flow (ischemia) for 2 h. In addition to one noninterventional ischemia-exposed strip group, a second group was externally paced at a fixed rate (55 pulses·min–1, 6 V) and a third "ischemia" group was treated with isoproterenol (0.1 mM), both interventions commencing upon the strips' exposure to the hepatic effluents. Control strips displayed unaltered contraction rate and systolic-generated tension during the 2-h exposure. Nontreated strips exposed to ischemic reperfusate experienced bradycardia compared with baseline values (7 ± 2 vs. 50 ± 12 beats·min–1, p < 0.05), followed <1-min later by a fall in the generated tension (11 ± 4 vs. 20 ± 6 mmHg, p < 0.05). The paced-ischemic strips displayed unaltered rate and force of contraction, whereas the addition of isoproterenol did not prevent deterioration in the rate and force of contraction (8 ± 3 beats·min–1, 12 ± 4 mmHg, respectively; p < 0.05 vs. baseline control ischemia-paced strips). Thus, external electrical pacing prevented liver ischemia–reperfusion-induced atrial strips' bradycardia and loss of contractility, while isoproterenol did not.Key words: ischemia, reperfusion, liver, atrium, dysfunction, isoproterenol, pacing.
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Affiliation(s)
- Ron Ben-Abraham
- Department of Anesthesiology and Critical Care, Tel Aviv Sourasky Medical School, 6 Weizman Street, Tel Aviv 64239, Israel
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Tucci PJF, Sant'Ana O, Nogueira RJ, Murad N, Lopes AC, Sañudo A, Peres CA. Stunning and myocardial contractile autoregulation studied on the isolated isovolumic blood-perfused dog heart. ACTA PHYSIOLOGICA SCANDINAVICA 2003; 179:263-71. [PMID: 14616242 DOI: 10.1046/j.0001-6772.2003.01172.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/27/2023]
Abstract
AIM To study, for the first time, the effects of stunning on homeometric and heterometric autoregulation. METHODS AND RESULTS Ischaemia (15 min)/reperfusion (30 min) was induced in the isovolumic blood-perfused dog heart preparation. Heart rate elevations (n = 9) from 60 to 200 beats min-1, in steps of 20 beats min-1, promoted the same inotropic stimulation in control (C) and stunning (S), indicating that ischaemia/reperfusion does not affect the changes in calcium kinetics elicited by the Bowditch effect. Sudden ventricular dilation (VD) (n = 10) evoked an instantaneous increase in developed pressure (Delta1DP) followed by a continuous slow performance increase (Delta2DP) in C and S. Delta1DP (C: 35 +/- 2.2 mmHg; S: 27 +/- 2.1 mmHg; P = 0.002) and Delta2DP (C: 20 +/- 1.6 mmHg; S: 14 +/- 1.3 mmHg; P = 0.002) decreased proportionally, while Delta2/Delta1DP (C: 0.57 +/- 0.13; S: 0.58 +/- 0.14) and slow response time course (T/2) were unchanged (C: 55 +/- 6.6 s; S: 57 +/- 7.7 s) after ischaemia/reperfusion. The reduction of Delta1DP can be understood as a decline of the myofilaments calcium responsiveness, the main pathophysiological effect of stunning. The reason for the weakening of Delta2DP, due to intracellular calcium gain, was not determined but it was supposed that its complete manifestation could be restricted by cyclic adenosine monophosphate (cAMP) myocardial content reduction. As reported by others, Delta2DP depends on myocardial cAMP, and it has been shown that myocardial cAMP is decreased after ischaemia/reperfusion. CONCLUSIONS Contractile depression due to stunning has no effect on the inotropic stimulation generated by the Bowditch phenomenon. Immediate and time-dependent enhancements of contraction evoked by sudden VD are proportionally reduced and the slow response time course is unaffected in the stunned myocardium.
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Affiliation(s)
- P J F Tucci
- Cardiovascular Physiology, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil Biostatistic Divisions, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
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Bombardini T, Correia MJ, Cicerone C, Agricola E, Ripoli A, Picano E. Force-frequency relationship in the echocardiography laboratory: a noninvasive assessment of Bowditch treppe? J Am Soc Echocardiogr 2003; 16:646-55. [PMID: 12778025 DOI: 10.1016/s0894-7317(03)00221-9] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
BACKGROUND Estimation of contractility of the left ventricle is an important, and as yet elusive, goal with noninvasive techniques. OBJECTIVE We sought to assess the feasibility of a totally noninvasive estimation of force-frequency relation (FFR) during exercise stress in the echocardiography laboratory. METHODS We enrolled 13 healthy control patients (12 men, age 38 +/- 15 years) as group I, and 50 patients (38 men, age 64 +/- 11 years) referred for exercise echocardiography as group II. To build the FFR, the force was determined at each step as the ratio of the systolic pressure (cuff sphygmomanometer)/end-systolic volume index (biplane Simpson's rule/body surface area). The slope of the relationship was calculated with the linear best fit of the FFR. RESULTS Noninvasive systolic pressure/end-systolic volume ratio was obtained in all patients. The slope of the linear best fit of the force-frequency curve was lower in group II compared with group I (group II = 10.1 +/- 9.3 x 10(-2) vs group I = 14.9 +/- 9.9 x 10(-2) group I, P =.04). By regional wall-motion analysis, 2 subgroups were identified in group II: group IIA (n = 8) had a positive echocardiogram; and group IIB (n = 42) had a negative echocardiogram. The slope of the force-frequency curve was lower in patients with ischemia compared with those without (group IIA = 3.5 +/- 4.2 x 10(-2) vs group IIB = 11.4 +/- 9.5 x 10(-2); P =.012). Heart rate-systolic pressure/end-systolic volume index relation was biphasic, with an initial positive slope and a subsequent negative slope in 1 patient of group I, 4 patients of group IIA, and 15 patients of group IIB (P <.05 vs group I). CONCLUSION A noninvasive estimation of FFR can be easily determined during exercise echocardiography. This index of global contractility is theoretically appealing for identification of limited contractile reserve and latent global left ventricular dysfunction.
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Guo J, Duff HJ. Inactivation of ICa-L is the major determinant of use-dependent facilitation in rat cardiomyocytes. J Physiol 2003; 547:797-805. [PMID: 12562907 PMCID: PMC2342727 DOI: 10.1113/jphysiol.2002.033340] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Two models have been proposed to explain facilitation of the L-type calcium current (ICa-L). A positive feedback model proposes that calcium released during a conditioning pulse (I1) facilitates the subsequent pulse (I2) via calmodulin/calmodulin kinase II (CaMKII) mechanisms. The negative feedback model proposes that the calcium release of each pulse feeds back on itself via calcium-dependent inactivation. The relative physiological roles were evaluated in rat ventricular myocytes. Paired pulses (450 ms interpulse interval) elicited facilitation (I2 of 872 +/- 145 versus I1 of 777 +/- 132 pA, P < 0.01). Inactivation time (T0.37) was prolonged for I2 versus I1 (22 +/- 2 and 16 +/- 2 ms, P > 0.01). Evidence for the negative feedback mechanism includes: (a) ryanodine (0.3 mM ) eliminated facilitation, surprisingly by increasing the amplitude of I1 more than that of I2 (1039 +/- 216 and 977 +/- 186 pA) and eliminated the difference in T0.37 between I2 and I1 (33.1 +/- 4.5 versus 32.5 +/- 4.6 ms); (b) an outward I2, which does not trigger sarcoplasmic reticulum (SR) Ca2+ release, eliminated facilitation even when it was conditioned by an inward I1; (c) facilitation decayed as the I1-I2 interval lengthened (time constant (tau) = 16.9 +/- 1.4 s); (d) thapsigargin (0.1 microM ) slowed this decay (tau = 43.8 +/- 11.7 s) whereas isoproterenol accelerated it (tau = 5.6 +/- 1.4 s, P < 0.01) and T0.37 paralleled this decay; and (e) the magnitude of ICa-L was negatively correlated with the sodium-calcium exchange current (INa/Ca) elicited by the SR-Ca2+ release. In conclusion, Ca2+-dependent inactivation of ICa-L is the major mechanism underlying facilitation.
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Affiliation(s)
- J Guo
- Department of Medicine, University of Calgary, Calgary, Alberta, Canada T2N 4N1
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