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Asfaw TN, Bondarenko VE. A compartmentalized mathematical model of the β 1- and β 2-adrenergic signaling systems in ventricular myocytes from mouse in heart failure. Am J Physiol Cell Physiol 2023; 324:C263-C291. [PMID: 36468844 DOI: 10.1152/ajpcell.00366.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Mouse models of heart failure are extensively used to research human cardiovascular diseases. In particular, one of the most common is the mouse model of heart failure resulting from transverse aortic constriction (TAC). Despite this, there are no comprehensive compartmentalized mathematical models that describe the complex behavior of the action potential, [Ca2+]i transients, and their regulation by β1- and β2-adrenergic signaling systems in failing mouse myocytes. In this paper, we develop a novel compartmentalized mathematical model of failing mouse ventricular myocytes after TAC procedure. The model describes well the cell geometry, action potentials, [Ca2+]i transients, and β1- and β2-adrenergic signaling in the failing cells. Simulation results obtained with the failing cell model are compared with those from the normal ventricular myocytes. Exploration of the model reveals the sarcoplasmic reticulum Ca2+ load mechanisms in failing ventricular myocytes. We also show a larger susceptibility of the failing myocytes to early and delayed afterdepolarizations and to a proarrhythmic behavior of Ca2+ dynamics upon stimulation with isoproterenol. The mechanisms of the proarrhythmic behavior suppression are investigated and sensitivity analysis is performed. The developed model can explain the existing experimental data on failing mouse ventricular myocytes and make experimentally testable predictions of a failing myocyte's behavior.
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Affiliation(s)
- Tesfaye Negash Asfaw
- Department of Mathematics and Statistics, Georgia State University, Atlanta, Georgia
| | - Vladimir E Bondarenko
- Department of Mathematics and Statistics, Georgia State University, Atlanta, Georgia.,Neuroscience Institute, Georgia State University, Atlanta, Georgia
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Hua X, Wang YY, Jia P, Xiong Q, Hu Y, Chang Y, Lai S, Xu Y, Zhao Z, Song J. Multi-level transcriptome sequencing identifies COL1A1 as a candidate marker in human heart failure progression. BMC Med 2020; 18:2. [PMID: 31902369 PMCID: PMC6943904 DOI: 10.1186/s12916-019-1469-4] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 11/19/2019] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Heart failure (HF) has been recognized as a global pandemic with a high rate of hospitalization, morbidity, and mortality. Although numerous advances have been made, its representative molecular signatures remain largely unknown, especially the role of genes in HF progression. The aim of the present prospective follow-up study was to reveal potential biomarkers associated with the progression of heart failure. METHODS We generated multi-level transcriptomic data from a cohort of left ventricular heart tissue collected from 21 HF patients and 9 healthy donors. By using Masson staining to calculate the fibrosis percentage for each sample, we applied lasso regression model to identify the genes associated with fibrosis as well as progression. The genes were further validated by immunohistochemistry (IHC) staining in the same cohort and qRT-PCR using another independent cohort (20 HF and 9 healthy donors). Enzyme-linked immunosorbent assay (ELISA) was used to measure the plasma level in a validation cohort (139 HF patients) for predicting HF progression. RESULTS Based on the multi-level transcriptomic data, we examined differentially expressed genes [mRNAs, microRNAs, and long non-coding RNAs (lncRNAs)] in the study cohort. The follow-up functional annotation and regulatory network analyses revealed their potential roles in regulating extracellular matrix. We further identified several genes that were associated with fibrosis. By using the survival time before transplantation, COL1A1 was identified as a potential biomarker for HF progression and its upregulation was confirmed by both IHC and qRT-PCR. Furthermore, COL1A1 content ≥ 256.5 ng/ml in plasma was found to be associated with poor survival within 1 year of heart transplantation from heart failure [hazard ratio (HR) 7.4, 95% confidence interval (CI) 3.5 to 15.8, Log-rank p value < 1.0 × 10- 4]. CONCLUSIONS Our results suggested that COL1A1 might be a plasma biomarker of HF and associated with HF progression, especially to predict the 1-year survival from HF onset to transplantation.
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Affiliation(s)
- Xiumeng Hua
- Department of Cardiac Surgery, State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, 167A Beilishi Road, Xi Cheng District, Beijing, 10037, China
| | - Yin-Ying Wang
- Center for Precision Health, School of Biomedical Informatics, The University of Texas Health Science Center at Houston, 7000 Fannin St, Houston, TX, 77030, USA
| | - Peilin Jia
- Center for Precision Health, School of Biomedical Informatics, The University of Texas Health Science Center at Houston, 7000 Fannin St, Houston, TX, 77030, USA
| | - Qing Xiong
- Center for Precision Health, School of Biomedical Informatics, The University of Texas Health Science Center at Houston, 7000 Fannin St, Houston, TX, 77030, USA
| | - Yiqing Hu
- Department of Cardiac Surgery, State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, 167A Beilishi Road, Xi Cheng District, Beijing, 10037, China
| | - Yuan Chang
- Department of Cardiac Surgery, State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, 167A Beilishi Road, Xi Cheng District, Beijing, 10037, China
| | - Songqing Lai
- Department of Cardiac Surgery, State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, 167A Beilishi Road, Xi Cheng District, Beijing, 10037, China
| | - Yong Xu
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA
| | - Zhongming Zhao
- Center for Precision Health, School of Biomedical Informatics, The University of Texas Health Science Center at Houston, 7000 Fannin St, Houston, TX, 77030, USA. .,Human Genetics Center, School of Public Health, The University of Texas Health Science Center at Houston, 1200 Pressler St, Houston, TX, 77030, USA. .,Department of Biomedical Informatics, Vanderbilt University Medical Center, 2525 West End Avenue, Nashville, TN, 37203, USA.
| | - Jiangping Song
- Department of Cardiac Surgery, State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, 167A Beilishi Road, Xi Cheng District, Beijing, 10037, China.
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Di Achille P, Parikh J, Khamzin S, Solovyova O, Kozloski J, Gurev V. Model order reduction for left ventricular mechanics via congruency training. PLoS One 2020; 15:e0219876. [PMID: 31905197 PMCID: PMC6944464 DOI: 10.1371/journal.pone.0219876] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Accepted: 12/10/2019] [Indexed: 12/20/2022] Open
Abstract
Computational models of the cardiovascular system and specifically heart function are currently being investigated as analytic tools to assist medical practice and clinical trials. To achieve clinical utility, models should be able to assimilate the diagnostic multi-modality data available for each patient and generate consistent representations of the underlying cardiovascular physiology. While finite element models of the heart can naturally account for patient-specific anatomies reconstructed from medical images, optimizing the many other parameters driving simulated cardiac functions is challenging due to computational complexity. With the goal of streamlining parameter adaptation, in this paper we present a novel, multifidelity strategy for model order reduction of 3-D finite element models of ventricular mechanics. Our approach is centered around well established findings on the similarity between contraction of an isolated muscle and the whole ventricle. Specifically, we demonstrate that simple linear transformations between sarcomere strain (tension) and ventricular volume (pressure) are sufficient to reproduce global pressure-volume outputs of 3-D finite element models even by a reduced model with just a single myocyte unit. We further develop a procedure for congruency training of a surrogate low-order model from multi-scale finite elements, and we construct an example of parameter optimization based on medical images. We discuss how the presented approach might be employed to process large datasets of medical images as well as databases of echocardiographic reports, paving the way towards application of heart mechanics models in the clinical practice.
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Affiliation(s)
- Paolo Di Achille
- Healthcare and Life Sciences Research, IBM T.J. Watson Research Center, Yorktown Heights, NY, United States of America
| | - Jaimit Parikh
- Healthcare and Life Sciences Research, IBM T.J. Watson Research Center, Yorktown Heights, NY, United States of America
| | - Svyatoslav Khamzin
- Ural Federal University, Yekaterinburg, Russia
- Institute of Immunology and Physiology, Ural Branch of the Russian Academy of Sciences (UB RAS), Yekaterinburg, Russia
| | - Olga Solovyova
- Ural Federal University, Yekaterinburg, Russia
- Institute of Immunology and Physiology, Ural Branch of the Russian Academy of Sciences (UB RAS), Yekaterinburg, Russia
| | - James Kozloski
- Healthcare and Life Sciences Research, IBM T.J. Watson Research Center, Yorktown Heights, NY, United States of America
| | - Viatcheslav Gurev
- Healthcare and Life Sciences Research, IBM T.J. Watson Research Center, Yorktown Heights, NY, United States of America
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Mora MT, Gomez JF, Morley G, Ferrero JM, Trenor B. Mechanistic investigation of Ca2+ alternans in human heart failure and its modulation by fibroblasts. PLoS One 2019; 14:e0217993. [PMID: 31211790 PMCID: PMC6581251 DOI: 10.1371/journal.pone.0217993] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Accepted: 05/22/2019] [Indexed: 11/18/2022] Open
Abstract
Background Heart failure (HF) is characterized, among other factors, by a progressive loss of contractile function and by the formation of an arrhythmogenic substrate, both aspects partially related to intracellular Ca2+ cycling disorders. In failing hearts both electrophysiological and structural remodeling, including fibroblast proliferation, contribute to changes in Ca2+ handling which promote the appearance of Ca2+ alternans (Ca-alt). Ca-alt in turn give rise to repolarization alternans, which promote dispersion of repolarization and contribute to reentrant activity. The computational analysis of the incidence of Ca2+ and/or repolarization alternans under HF conditions in the presence of fibroblasts could provide a better understanding of the mechanisms leading to HF arrhythmias and contractile function disorders. Methods and findings The goal of the present study was to investigate in silico the mechanisms leading to the formation of Ca-alt in failing human ventricular myocytes and tissues with disperse fibroblast distributions. The contribution of ionic currents variability to alternans formation at the cellular level was analyzed and the results show that in normal ventricular tissue, altered Ca2+ dynamics lead to Ca-alt, which precede APD alternans and can be aggravated by the presence of fibroblasts. Electrophysiological remodeling of failing tissue alone is sufficient to develop alternans. The incidence of alternans is reduced when fibroblasts are present in failing tissue due to significantly depressed Ca2+ transients. The analysis of the underlying ionic mechanisms suggests that Ca-alt are driven by Ca2+-handling protein and Ca2+ cycling dysfunctions in the junctional sarcoplasmic reticulum and that their contribution to alternans occurrence depends on the cardiac remodeling conditions and on myocyte-fibroblast interactions. Conclusion It can thus be concluded that fibroblasts modulate the formation of Ca-alt in human ventricular tissue subjected to heart failure-related electrophysiological remodeling. Pharmacological therapies should thus consider the extent of both the electrophysiological and structural remodeling present in the failing heart.
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Affiliation(s)
- Maria T. Mora
- Centro de Insvestigación e Innovación en Bioingeniería, Universitat Politècnica de València, Valencia, Spain
| | - Juan F. Gomez
- Centro de Insvestigación e Innovación en Bioingeniería, Universitat Politècnica de València, Valencia, Spain
| | - Gregory Morley
- Leon H. Charney Division of Cardiology, New York University School of Medicine, New York, New York, United States of America
| | - Jose M. Ferrero
- Centro de Insvestigación e Innovación en Bioingeniería, Universitat Politècnica de València, Valencia, Spain
| | - Beatriz Trenor
- Centro de Insvestigación e Innovación en Bioingeniería, Universitat Politècnica de València, Valencia, Spain
- * E-mail:
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Hegyi B, Morotti S, Liu C, Ginsburg KS, Bossuyt J, Belardinelli L, Izu LT, Chen-Izu Y, Bányász T, Grandi E, Bers DM. Enhanced Depolarization Drive in Failing Rabbit Ventricular Myocytes: Calcium-Dependent and β-Adrenergic Effects on Late Sodium, L-Type Calcium, and Sodium-Calcium Exchange Currents. Circ Arrhythm Electrophysiol 2019; 12:e007061. [PMID: 30879336 PMCID: PMC6720130 DOI: 10.1161/circep.118.007061] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND Heart failure (HF) is characterized by electrophysiological remodeling resulting in increased risk of cardiac arrhythmias. Previous reports suggest that elevated inward ionic currents in HF promote action potential (AP) prolongation, increased short-term variability of AP repolarization, and delayed afterdepolarizations. However, the underlying changes in late Na+ current (INaL), L-type Ca2+ current, and NCX (Na+/Ca2+ exchanger) current are often measured in nonphysiological conditions (square-pulse voltage clamp, slow pacing rates, exogenous Ca2+ buffers). METHODS We measured the major inward currents and their Ca2+- and β-adrenergic dependence under physiological AP clamp in rabbit ventricular myocytes in chronic pressure/volume overload-induced HF (versus age-matched control). RESULTS AP duration and short-term variability of AP repolarization were increased in HF, and importantly, inhibition of INaL decreased both parameters to the control level. INaL was slightly increased in HF versus control even when intracellular Ca2+ was strongly buffered. But under physiological AP clamp with normal Ca2+ cycling, INaL was markedly upregulated in HF versus control (dependent largely on CaMKII [Ca2+/calmodulin-dependent protein kinase II] activity). β-Adrenergic stimulation (often elevated in HF) further enhanced INaL. L-type Ca2+ current was decreased in HF when Ca2+ was buffered, but CaMKII-mediated Ca2+-dependent facilitation upregulated physiological L-type Ca2+ current to the control level. Furthermore, L-type Ca2+ current response to β-adrenergic stimulation was significantly attenuated in HF. Inward NCX current was upregulated at phase 3 of AP in HF when assessed by combining experimental data and computational modeling. CONCLUSIONS Our results suggest that CaMKII-dependent upregulation of INaL in HF significantly contributes to AP prolongation and increased short-term variability of AP repolarization, which may lead to increased arrhythmia propensity, and is further exacerbated by adrenergic stress.
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Affiliation(s)
- Bence Hegyi
- Department of Pharmacology, University of California Davis, Davis
| | - Stefano Morotti
- Department of Pharmacology, University of California Davis, Davis
| | - Caroline Liu
- Department of Pharmacology, University of California Davis, Davis
| | | | - Julie Bossuyt
- Department of Pharmacology, University of California Davis, Davis
| | | | - Leighton T. Izu
- Department of Pharmacology, University of California Davis, Davis
| | - Ye Chen-Izu
- Department of Pharmacology, University of California Davis, Davis
- Department of Biomedical Engineering, University of California Davis, Davis
- Department of Internal Medicine/Cardiology, University of California Davis, Davis
| | - Tamás Bányász
- Department of Pharmacology, University of California Davis, Davis
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Eleonora Grandi
- Department of Pharmacology, University of California Davis, Davis
| | - Donald M. Bers
- Department of Pharmacology, University of California Davis, Davis
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6
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Gintant GA, George CH. Introduction to biological complexity as a missing link in drug discovery. Expert Opin Drug Discov 2018; 13:753-763. [PMID: 29871539 DOI: 10.1080/17460441.2018.1480608] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
INTRODUCTION Despite a burgeoning knowledge of the intricacies and mechanisms responsible for human disease, technological advances in medicinal chemistry, and more efficient assays used for drug screening, it remains difficult to discover novel and effective pharmacologic therapies. Areas covered: By reference to the primary literature and concepts emerging from academic and industrial drug screening landscapes, the authors propose that this disconnect arises from the inability to scale and integrate responses from simpler model systems to outcomes from more complex and human-based biological systems. Expert opinion: Further collaborative efforts combining target-based and phenotypic-based screening along with systems-based pharmacology and informatics will be necessary to harness the technological breakthroughs of today to derive the novel drug candidates of tomorrow. New questions must be asked of enabling technologies-while recognizing inherent limitations-in a way that moves drug development forward. Attempts to integrate mechanistic and observational information acquired across multiple scales frequently expose the gap between our knowledge and our understanding as the level of complexity increases. We hope that the thoughts and actionable items highlighted will help to inform the directed evolution of the drug discovery process.
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Affiliation(s)
- Gary A Gintant
- a AbbVie, Department of Integrative Pharmacology , Integrated Science and Technology , North Chicago , IL , USA
| | - Christopher H George
- b Molecular Cardiology, Institute of Life Sciences , Swansea University Medical School , Swansea , Wales , UK
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Mora MT, Ferrero JM, Romero L, Trenor B. Sensitivity analysis revealing the effect of modulating ionic mechanisms on calcium dynamics in simulated human heart failure. PLoS One 2017; 12:e0187739. [PMID: 29117223 PMCID: PMC5678731 DOI: 10.1371/journal.pone.0187739] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Accepted: 10/25/2017] [Indexed: 12/27/2022] Open
Abstract
Abnormal intracellular Ca2+ handling is the major contributor to the depressed cardiac contractility observed in heart failure. The electrophysiological remodeling associated with this pathology alters both the action potential and the Ca2+ dynamics, leading to a defective excitation-contraction coupling that ends in mechanical dysfunction. The importance of maintaining a correct intracellular Ca2+ concentration requires a better understanding of its regulation by ionic mechanisms. To study the electrical activity and ionic homeostasis of failing myocytes, a modified version of the O’Hara et al. human action potential model was used, including electrophysiological remodeling. The impact of the main ionic transport mechanisms was analyzed using single-parameter sensitivity analyses, the first of which explored the modulation of electrophysiological characteristics related to Ca2+ exerted by the remodeled parameters. The second sensitivity analysis compared the potential consequences of modulating individual channel conductivities, as one of the main effects of potential drugs, on Ca2+ dynamic properties under both normal conditions and in heart failure. The first analysis revealed the important contribution of the sarcoplasmic reticulum Ca2+-ATPase (SERCA) dysfunction to the altered Ca2+ homeostasis, with the Na+/Ca2+ exchanger (NCX) and other Ca2+ cycling proteins also playing a significant role. Our results highlight the importance of improving the SR uptake function to increase Ca2+ content and restore Ca2+ homeostasis and contractility. The second sensitivity analysis highlights the different response of the failing myocyte versus the healthy myocyte to potential pharmacological actions on single channels. The result of modifying the conductances of the remodeled proteins such as SERCA and NCX in heart failure has less impact on Ca2+ modulation. These differences should be taken into account when designing drug therapies.
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Affiliation(s)
- Maria T. Mora
- Centro de Investigación e Innovación en Bioingeniería, Universitat Politècnica de València, Valencia, Spain
| | - Jose M. Ferrero
- Centro de Investigación e Innovación en Bioingeniería, Universitat Politècnica de València, Valencia, Spain
| | - Lucia Romero
- Centro de Investigación e Innovación en Bioingeniería, Universitat Politècnica de València, Valencia, Spain
| | - Beatriz Trenor
- Centro de Investigación e Innovación en Bioingeniería, Universitat Politècnica de València, Valencia, Spain
- * E-mail:
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8
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Bai X, Wang K, Yuan Y, Li Q, Dobrzynski H, Boyett MR, Hancox JC, Zhang H. Mechanism underlying impaired cardiac pacemaking rhythm during ischemia: A simulation study. CHAOS (WOODBURY, N.Y.) 2017; 27:093934. [PMID: 28964153 DOI: 10.1063/1.5002664] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Ischemia in the heart impairs function of the cardiac pacemaker, the sinoatrial node (SAN). However, the ionic mechanisms underlying the ischemia-induced dysfunction of the SAN remain elusive. In order to investigate the ionic mechanisms by which ischemia causes SAN dysfunction, action potential models of rabbit SAN and atrial cells were modified to incorporate extant experimental data of ischemia-induced changes to membrane ion channels and intracellular ion homeostasis. The cell models were incorporated into an anatomically detailed 2D model of the intact SAN-atrium. Using the multi-scale models, the functional impact of ischemia-induced electrical alterations on cardiac pacemaking action potentials (APs) and their conduction was investigated. The effects of vagal tone activity on the regulation of cardiac pacemaker activity in control and ischemic conditions were also investigated. The simulation results showed that at the cellular level ischemia slowed the SAN pacemaking rate, which was mainly attributable to the altered Na+-Ca2+ exchange current and the ATP-sensitive potassium current. In the 2D SAN-atrium tissue model, ischemia slowed down both the pacemaking rate and the conduction velocity of APs into the surrounding atrial tissue. Simulated vagal nerve activity, including the actions of acetylcholine in the model, amplified the effects of ischemia, leading to possible SAN arrest and/or conduction exit block, which are major features of the sick sinus syndrome. In conclusion, this study provides novel insights into understanding the mechanisms by which ischemia alters SAN function, identifying specific conductances as contributors to bradycardia and conduction block.
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Affiliation(s)
- Xiangyun Bai
- School of Computer Science and Technology, Harbin Institute of Technology, Harbin 150001, China
| | - Kuanquan Wang
- School of Computer Science and Technology, Harbin Institute of Technology, Harbin 150001, China
| | - Yongfeng Yuan
- School of Computer Science and Technology, Harbin Institute of Technology, Harbin 150001, China
| | - Qince Li
- School of Computer Science and Technology, Harbin Institute of Technology, Harbin 150001, China
| | - Halina Dobrzynski
- Institute of Cardiovascular Sciences, The University of Manchester, M13 9PL Manchester, United Kingdom
| | - Mark R Boyett
- Institute of Cardiovascular Sciences, The University of Manchester, M13 9PL Manchester, United Kingdom
| | - Jules C Hancox
- Biological Physics Group, School of Physics and Astronomy, The University of Manchester, M13 9PL Manchester, United Kingdom
| | - Henggui Zhang
- School of Computer Science and Technology, Harbin Institute of Technology, Harbin 150001, China
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Maffessanti F, Wanten J, Potse M, Regoli F, Caputo ML, Conte G, Sürder D, Illner A, Krause R, Moccetti T, Auricchio A, Prinzen FW. The relation between local repolarization and T-wave morphology in heart failure patients. Int J Cardiol 2017; 241:270-276. [DOI: 10.1016/j.ijcard.2017.02.056] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 02/15/2017] [Indexed: 11/16/2022]
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10
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Chai S, Wan X, Nassal DM, Liu H, Moravec CS, Ramirez-Navarro A, Deschênes I. Contribution of two-pore K + channels to cardiac ventricular action potential revealed using human iPSC-derived cardiomyocytes. Am J Physiol Heart Circ Physiol 2017; 312:H1144-H1153. [PMID: 28341634 DOI: 10.1152/ajpheart.00107.2017] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 03/16/2017] [Accepted: 03/22/2017] [Indexed: 01/12/2023]
Abstract
Two-pore K+ (K2p) channels have been described in modulating background conductance as leak channels in different physiological systems. In the heart, the expression of K2p channels is heterogeneous with equivocation regarding their functional role. Our objective was to determine the K2p expression profile and their physiological and pathophysiological contribution to cardiac electrophysiology. Induced pluripotent stem cells (iPSCs) generated from humans were differentiated into cardiomyocytes (iPSC-CMs). mRNA was isolated from these cells, commercial iPSC-CM (iCells), control human heart ventricular tissue (cHVT), and ischemic (iHF) and nonischemic heart failure tissues (niHF). We detected 10 K2p channels in the heart. Comparing quantitative PCR expression of K2p channels between human heart tissue and iPSC-CMs revealed K2p1.1, K2p2.1, K2p5.1, and K2p17.1 to be higher expressed in cHVT, whereas K2p3.1 and K2p13.1 were higher in iPSC-CMs. Notably, K2p17.1 was significantly lower in niHF tissues compared with cHVT. Action potential recordings in iCells after K2p small interfering RNA knockdown revealed prolongations in action potential depolarization at 90% repolarization for K2p2.1, K2p3.1, K2p6.1, and K2p17.1. Here, we report the expression level of 10 human K2p channels in iPSC-CMs and how they compared with cHVT. Importantly, our functional electrophysiological data in human iPSC-CMs revealed a prominent role in cardiac ventricular repolarization for four of these channels. Finally, we also identified K2p17.1 as significantly reduced in niHF tissues and K2p4.1 as reduced in niHF compared with iHF. Thus, we advance the notion that K2p channels are emerging as novel players in cardiac ventricular electrophysiology that could also be remodeled in cardiac pathology and therefore contribute to arrhythmias.NEW & NOTEWORTHY Two-pore K+ (K2p) channels are traditionally regarded as merely background leak channels in myriad physiological systems. Here, we describe the expression profile of K2p channels in human-induced pluripotent stem cell-derived cardiomyocytes and outline a salient role in cardiac repolarization and pathology for multiple K2p channels.
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Affiliation(s)
- Sam Chai
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, Ohio.,Heart and Vascular Research Center, Department of Medicine, MetroHealth Campus, Case Western Reserve University, Cleveland, Ohio; and
| | - Xiaoping Wan
- Heart and Vascular Research Center, Department of Medicine, MetroHealth Campus, Case Western Reserve University, Cleveland, Ohio; and
| | - Drew M Nassal
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, Ohio.,Heart and Vascular Research Center, Department of Medicine, MetroHealth Campus, Case Western Reserve University, Cleveland, Ohio; and
| | - Haiyan Liu
- Heart and Vascular Research Center, Department of Medicine, MetroHealth Campus, Case Western Reserve University, Cleveland, Ohio; and
| | | | - Angelina Ramirez-Navarro
- Heart and Vascular Research Center, Department of Medicine, MetroHealth Campus, Case Western Reserve University, Cleveland, Ohio; and
| | - Isabelle Deschênes
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, Ohio; .,Heart and Vascular Research Center, Department of Medicine, MetroHealth Campus, Case Western Reserve University, Cleveland, Ohio; and
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11
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Cardona K, Trenor B, Giles WR. Changes in Intracellular Na+ following Enhancement of Late Na+ Current in Virtual Human Ventricular Myocytes. PLoS One 2016; 11:e0167060. [PMID: 27875582 PMCID: PMC5119830 DOI: 10.1371/journal.pone.0167060] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 11/08/2016] [Indexed: 12/19/2022] Open
Abstract
The slowly inactivating or late Na+ current, INa-L, can contribute to the initiation of both atrial and ventricular rhythm disturbances in the human heart. However, the cellular and molecular mechanisms that underlie these pro-arrhythmic influences are not fully understood. At present, the major working hypothesis is that the Na+ influx corresponding to INa-L significantly increases intracellular Na+, [Na+]i; and the resulting reduction in the electrochemical driving force for Na+ reduces and (may reverse) Na+/Ca2+ exchange. These changes increase intracellular Ca2+, [Ca2+]i; which may further enhance INa-L due to calmodulin-dependent phosphorylation of the Na+ channels. This paper is based on mathematical simulations using the O'Hara et al (2011) model of baseline or healthy human ventricular action potential waveforms(s) and its [Ca2+]i homeostasis mechanisms. Somewhat surprisingly, our results reveal only very small changes (≤ 1.5 mM) in [Na+]i even when INa-L is increased 5-fold and steady-state stimulation rate is approximately 2 times the normal human heart rate (i.e. 2 Hz). Previous work done using well-established models of the rabbit and human ventricular action potential in heart failure settings also reported little or no change in [Na+]i when INa-L was increased. Based on our simulations, the major short-term effect of markedly augmenting INa-L is a significant prolongation of the action potential and an associated increase in the likelihood of reactivation of the L-type Ca2+ current, ICa-L. Furthermore, this action potential prolongation does not contribute to [Na+]i increase.
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Affiliation(s)
- Karen Cardona
- Centro de Investigación e Innovación en Bioingeniería, Universitat Politècnica de València, Valencia, Spain
| | - Beatriz Trenor
- Centro de Investigación e Innovación en Bioingeniería, Universitat Politècnica de València, Valencia, Spain
- * E-mail:
| | - Wayne R. Giles
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
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Quinn TA, Kohl P. Rabbit models of cardiac mechano-electric and mechano-mechanical coupling. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2016; 121:110-22. [PMID: 27208698 PMCID: PMC5067302 DOI: 10.1016/j.pbiomolbio.2016.05.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Accepted: 05/01/2016] [Indexed: 12/11/2022]
Abstract
Cardiac auto-regulation involves integrated regulatory loops linking electrics and mechanics in the heart. Whereas mechanical activity is usually seen as 'the endpoint' of cardiac auto-regulation, it is important to appreciate that the heart would not function without feed-back from the mechanical environment to cardiac electrical (mechano-electric coupling, MEC) and mechanical (mechano-mechanical coupling, MMC) activity. MEC and MMC contribute to beat-by-beat adaption of cardiac output to physiological demand, and they are involved in various pathological settings, potentially aggravating cardiac dysfunction. Experimental and computational studies using rabbit as a model species have been integral to the development of our current understanding of MEC and MMC. In this paper we review this work, focusing on physiological and pathological implications for cardiac function.
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Affiliation(s)
- T Alexander Quinn
- Department of Physiology and Biophysics, Dalhousie University, Halifax, Canada.
| | - Peter Kohl
- Institute for Experimental Cardiovascular Medicine, University Heart Centre Freiburg - Bad Krozingen, Faculty of Medicine, University of Freiburg, Freiburg, Germany; National Heart and Lung Institute, Imperial College London, London, UK
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Electrophysiology of Heart Failure Using a Rabbit Model: From the Failing Myocyte to Ventricular Fibrillation. PLoS Comput Biol 2016; 12:e1004968. [PMID: 27336310 PMCID: PMC4919062 DOI: 10.1371/journal.pcbi.1004968] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 05/05/2016] [Indexed: 02/07/2023] Open
Abstract
Heart failure is a leading cause of death, yet its underlying electrophysiological (EP) mechanisms are not well understood. In this study, we use a multiscale approach to analyze a model of heart failure and connect its results to features of the electrocardiogram (ECG). The heart failure model is derived by modifying a previously validated electrophysiology model for a healthy rabbit heart. Specifically, in accordance with the heart failure literature, we modified the cell EP by changing both membrane currents and calcium handling. At the tissue level, we modeled the increased gap junction lateralization and lower conduction velocity due to downregulation of Connexin 43. At the biventricular level, we reduced the apex-to-base and transmural gradients of action potential duration (APD). The failing cell model was first validated by reproducing the longer action potential, slower and lower calcium transient, and earlier alternans characteristic of heart failure EP. Subsequently, we compared the electrical wave propagation in one dimensional cables of healthy and failing cells. The validated cell model was then used to simulate the EP of heart failure in an anatomically accurate biventricular rabbit model. As pacing cycle length decreases, both the normal and failing heart develop T-wave alternans, but only the failing heart shows QRS alternans (although moderate) at rapid pacing. Moreover, T-wave alternans is significantly more pronounced in the failing heart. At rapid pacing, APD maps show areas of conduction block in the failing heart. Finally, accelerated pacing initiated wave reentry and breakup in the failing heart. Further, the onset of VF was not observed with an upregulation of SERCA, a potential drug therapy, using the same protocol. The changes introduced at the cell and tissue level have increased the failing heart’s susceptibility to dynamic instabilities and arrhythmias under rapid pacing. However, the observed increase in arrhythmogenic potential is not due to a steepening of the restitution curve (not present in our model), but rather to a novel blocking mechanism. Ventricular fibrillation (VF) is one of the leading causes of sudden death. During VF, the electrical wave of activation in the heart breaks up chaotically. Consequently, the heart is unable to contract synchronously and pump blood to the rest of the body. In our work we formulate and validate a model of heart failure (HF) that allows us to evaluate the arrhythmogenic potential of individual and combined electrophysiological changes. In diagnostic cardiology, the electrocardiogram (ECG) is one of the most commonly used tools for detecting abnormalities in the heart electrophysiology. One of our goals is to use our numerical model to link changes at the cellular and tissue level in a failing heart to a numerically computed ECG. This allows us to characterize the precursor to and the risk of VF. In order to understand the mechanisms underlying VF in HF, we design a test that simulates a HF patient performing physical exercise. We show that under fast heart rates with changes in pacing, HF patients are more prone to VF due to a new conduction blocking mechanism. In the long term, our mathematical model is suitable for investigating the effect of drug therapies in HF.
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