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Sarkar A, Fanous KI, Marei I, Ding H, Ladjimi M, MacDonald R, Hollenberg MD, Anderson TJ, Hill MA, Triggle CR. Repurposing Metformin for the Treatment of Atrial Fibrillation: Current Insights. Vasc Health Risk Manag 2024; 20:255-288. [PMID: 38919471 PMCID: PMC11198029 DOI: 10.2147/vhrm.s391808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Accepted: 06/05/2024] [Indexed: 06/27/2024] Open
Abstract
Metformin is an orally effective anti-hyperglycemic drug that despite being introduced over 60 years ago is still utilized by an estimated 120 to 150 million people worldwide for the treatment of type 2 diabetes (T2D). Metformin is used off-label for the treatment of polycystic ovary syndrome (PCOS) and for pre-diabetes and weight loss. Metformin is a safe, inexpensive drug with side effects mostly limited to gastrointestinal issues. Prospective clinical data from the United Kingdom Prospective Diabetes Study (UKPDS), completed in 1998, demonstrated that metformin not only has excellent therapeutic efficacy as an anti-diabetes drug but also that good glycemic control reduced the risk of micro- and macro-vascular complications, especially in obese patients and thereby reduced the risk of diabetes-associated cardiovascular disease (CVD). Based on a long history of clinical use and an excellent safety record metformin has been investigated to be repurposed for numerous other diseases including as an anti-aging agent, Alzheimer's disease and other dementias, cancer, COVID-19 and also atrial fibrillation (AF). AF is the most frequently diagnosed cardiac arrythmia and its prevalence is increasing globally as the population ages. The argument for repurposing metformin for AF is based on a combination of retrospective clinical data and in vivo and in vitro pre-clinical laboratory studies. In this review, we critically evaluate the evidence that metformin has cardioprotective actions and assess whether the clinical and pre-clinical evidence support the use of metformin to reduce the risk and treat AF.
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Affiliation(s)
- Aparajita Sarkar
- Department of Medical Education, Weill Cornell Medicine-Qatar, Doha, Qatar
| | - Kareem Imad Fanous
- Department of Medical Education, Weill Cornell Medicine-Qatar, Doha, Qatar
| | - Isra Marei
- Department of Pharmacology & Medical Education, Weill Cornell Medicine- Qatar, Doha, Qatar
| | - Hong Ding
- Department of Pharmacology & Medical Education, Weill Cornell Medicine- Qatar, Doha, Qatar
| | - Moncef Ladjimi
- Department of Biochemistry & Medical Education, Weill Cornell Medicine-Qatar, Doha, Qatar
| | - Ross MacDonald
- Health Sciences Library, Weill Cornell Medicine-Qatar, Doha, Qatar
| | - Morley D Hollenberg
- Department of Physiology & Pharmacology, and Department of Medicine, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Todd J Anderson
- Department of Cardiac Sciences and Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Michael A Hill
- Dalton Cardiovascular Research Center & Department of Medical Pharmacology & Physiology, School of Medicine, University of Missouri, Columbia, Missouri, USA
| | - Chris R Triggle
- Department of Pharmacology & Medical Education, Weill Cornell Medicine- Qatar, Doha, Qatar
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2
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Shim G, Breinyn IB, Martínez-Calvo A, Rao S, Cohen DJ. Bioelectric stimulation controls tissue shape and size. Nat Commun 2024; 15:2938. [PMID: 38580690 PMCID: PMC10997591 DOI: 10.1038/s41467-024-47079-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Accepted: 03/20/2024] [Indexed: 04/07/2024] Open
Abstract
Epithelial tissues sheath organs and electro-mechanically regulate ion and water transport to regulate development, homeostasis, and hydrostatic organ pressure. Here, we demonstrate how external electrical stimulation allows us to control these processes in living tissues. Specifically, we electrically stimulate hollow, 3D kidneyoids and gut organoids and find that physiological-strength electrical stimulation of ∼ 5 - 10 V/cm powerfully inflates hollow tissues; a process we call electro-inflation. Electro-inflation is mediated by increased ion flux through ion channels/transporters and triggers subsequent osmotic water flow into the lumen, generating hydrostatic pressure that competes against cytoskeletal tension. Our computational studies suggest that electro-inflation is strongly driven by field-induced ion crowding on the outer surface of the tissue. Electrically stimulated tissues also break symmetry in 3D resulting from electrotaxis and affecting tissue shape. The ability of electrical cues to regulate tissue size and shape emphasizes the role and importance of the electrical micro-environment for living tissues.
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Affiliation(s)
- Gawoon Shim
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, 08540, NJ, USA
| | - Isaac B Breinyn
- Department of Quantitative and Computational Biology, Princeton University, Princeton, 08540, NJ, USA
| | - Alejandro Martínez-Calvo
- Princeton Center for Theoretical Science, Princeton University, Princeton, 08540, NJ, USA
- Department of Chemical and Biological Engineering, Princeton University, Princeton, 08540, NJ, USA
| | - Sameeksha Rao
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, 08540, NJ, USA
| | - Daniel J Cohen
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, 08540, NJ, USA.
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3
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Hoff CM, Sørensen J, Kero T, Bouchelouche K, Harms HJ, Frøkiær J, Gormsen LC, Tolbod LP. Quantitative and qualitative comparison of Rubidium-82 and Oxygen-15 water cardiac PET. J Nucl Cardiol 2024; 32:101796. [PMID: 38278706 DOI: 10.1016/j.nuclcard.2024.101796] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2024]
Abstract
BACKGROUND Differences in tracer characteristics may influence the interpretation of positron emission tomography myocardial perfusion imaging (MPI). We compare the reading of MPIs with a low-extraction retention tracer (82Rb) and a high-extraction non-retention tracer (15O-water) in a selected cohort of patients with known coronary artery disease (CAD). METHODS Thirty-nine patients with known CAD referred to 82Rb MPI due to angina underwent rest and stress imaging with both tracers and experienced MPI readers provided blinded consensus reads of all studies. In addition, a comparison of regional and global quantitative measures of perfusion was performed. RESULTS The results showed 74 % agreement in the reading of 82Rb and 15O-water MPI for regional reversible ischemia and global disease, and 82 % agreement for regional irreversible ischemia. The 15O-water MPI identified more cases of global disease (n = 12 (15O-water) vs n = 4 (82Rb), p = 0.03), whereas differences in reversible ischemia (n = 22 vs n = 16, p = 0.11) and, irreversible ischemia (n = 8 vs n = 11, p = 0.45) were not significant. The correlation between myocardial blood flow measured using the two tracers was similar to previous studies (R2 = 0.78) with wide limits of agreement (-0.93 to 0.84 ml/g/min). CONCLUSIONS Agreement between consensus readings of 82Rb and 15O-water MPI was good in patients with known CAD. In this limited size study, no significant differences in the identification of reversible and irreversible ischemia found, whereas 15O-water MPI had a higher positive rate for suspected global disease.
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Affiliation(s)
- Camilla Molich Hoff
- Department of Nuclear Medicine & PET, Aarhus University Hospital, Aarhus, Denmark
| | - Jens Sørensen
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark; Nuclear Medicine & PET, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
| | - Tanja Kero
- Nuclear Medicine & PET, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
| | - Kirsten Bouchelouche
- Department of Nuclear Medicine & PET, Aarhus University Hospital, Aarhus, Denmark
| | | | - Jørgen Frøkiær
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Lars C Gormsen
- Department of Nuclear Medicine & PET, Aarhus University Hospital, Aarhus, Denmark; Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Lars P Tolbod
- Department of Nuclear Medicine & PET, Aarhus University Hospital, Aarhus, Denmark; Department of Clinical Medicine, Aarhus University, Aarhus, Denmark.
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4
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Ni H, Grandi E. Computational Modeling of Cardiac Electrophysiology. Methods Mol Biol 2024; 2735:63-103. [PMID: 38038844 DOI: 10.1007/978-1-0716-3527-8_5] [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] [Indexed: 12/02/2023]
Abstract
Mathematical modeling and simulation are well-established and powerful tools to integrate experimental data of individual components of cardiac electrophysiology, excitation-contraction coupling, and regulatory signaling pathways, to gain quantitative and mechanistic insight into pathophysiological processes and guide therapeutic strategies. Here, we briefly describe the processes governing cardiac myocyte electrophysiology and Ca2+ handling and their regulation, as well as action potential propagation in tissue. We discuss the models and methods used to describe these phenomena, including procedures for model parameterization and validation, in addition to protocols for model interrogation and analysis and techniques that account for phenotypic variability and parameter uncertainty. Our objective is to provide a summary of basic concepts and approaches as a resource for scientists training in this discipline and for all researchers aiming to gain an understanding of cardiac modeling studies.
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Affiliation(s)
- Haibo Ni
- Department of Pharmacology, University of California, Davis, CA, USA.
| | - Eleonora Grandi
- Department of Pharmacology, University of California, Davis, CA, USA.
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5
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Mao F, Yang W. How Merkel cells transduce mechanical stimuli: A biophysical model of Merkel cells. PLoS Comput Biol 2023; 19:e1011720. [PMID: 38117763 PMCID: PMC10732429 DOI: 10.1371/journal.pcbi.1011720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2023] [Accepted: 11/27/2023] [Indexed: 12/22/2023] Open
Abstract
Merkel cells combine with Aβ afferents, producing slowly adapting type 1(SA1) responses to mechanical stimuli. However, how Merkel cells transduce mechanical stimuli into neural signals to Aβ afferents is still unclear. Here we develop a biophysical model of Merkel cells for mechanical transduction by incorporating main ingredients such as Ca2+ and K+ voltage-gated channels, Piezo2 channels, internal Ca2+ stores, neurotransmitters release, and cell deformation. We first validate our model with several experiments. Then we reveal that Ca2+ and K+ channels on the plasma membrane shape the depolarization of membrane potentials, further regulating the Ca2+ transients in the cells. We also show that Ca2+ channels on the plasma membrane mainly inspire the Ca2+ transients, while internal Ca2+ stores mainly maintain the Ca2+ transients. Moreover, we show that though Piezo2 channels are rapidly adapting mechanical-sensitive channels, they are sufficient to inspire sustained Ca2+ transients in Merkel cells, which further induce the release of neurotransmitters for tens of seconds. Thus our work provides a model that captures the membrane potentials and Ca2+ transients features of Merkel cells and partly explains how Merkel cells transduce the mechanical stimuli by Piezo2 channels.
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Affiliation(s)
- Fangtao Mao
- Research Center for Humanoid Sensing, Intelligent Perception Research Institute of Zhejiang Lab, Hangzhou, Zhejiang, China
| | - Wenzhen Yang
- Research Center for Humanoid Sensing, Intelligent Perception Research Institute of Zhejiang Lab, Hangzhou, Zhejiang, China
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6
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Dasí A, Pope MT, Wijesurendra RS, Betts TR, Sachetto R, Bueno‐Orovio A, Rodriguez B. What determines the optimal pharmacological treatment of atrial fibrillation? Insights from in silico trials in 800 virtual atria. J Physiol 2023; 601:4013-4032. [PMID: 37475475 PMCID: PMC10952228 DOI: 10.1113/jp284730] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Accepted: 07/05/2023] [Indexed: 07/22/2023] Open
Abstract
The best pharmacological treatment for each atrial fibrillation (AF) patient is unclear. We aim to exploit AF simulations in 800 virtual atria to identify key patient characteristics that guide the optimal selection of anti-arrhythmic drugs. The virtual cohort considered variability in electrophysiology and low voltage areas (LVA) and was developed and validated against experimental and clinical data from ionic currents to ECG. AF sustained in 494 (62%) atria, with large inward rectifier K+ current (IK1 ) and Na+ /K+ pump (INaK ) densities (IK1 0.11 ± 0.03 vs. 0.07 ± 0.03 S mF-1 ; INaK 0.68 ± 0.15 vs. 0.38 ± 26 S mF-1 ; sustained vs. un-sustained AF). In severely remodelled left atrium, with LVA extensions of more than 40% in the posterior wall, higher IK1 (median density 0.12 ± 0.02 S mF-1 ) was required for AF maintenance, and rotors localized in healthy right atrium. For lower LVA extensions, rotors could also anchor to LVA, in atria presenting short refractoriness (median L-type Ca2+ current, ICaL , density 0.08 ± 0.03 S mF-1 ). This atrial refractoriness, modulated by ICaL and fast Na+ current (INa ), determined pharmacological treatment success for both small and large LVA. Vernakalant was effective in atria presenting long refractoriness (median ICaL density 0.13 ± 0.05 S mF-1 ). For short refractoriness, atria with high INa (median density 8.92 ± 2.59 S mF-1 ) responded more favourably to amiodarone than flecainide, and the opposite was found in atria with low INa (median density 5.33 ± 1.41 S mF-1 ). In silico drug trials in 800 human atria identify inward currents as critical for optimal stratification of AF patient to pharmacological treatment and, together with the left atrial LVA extension, for accurately phenotyping AF dynamics. KEY POINTS: Atrial fibrillation (AF) maintenance is facilitated by small L-type Ca2+ current (ICaL ) and large inward rectifier K+ current (IK1 ) and Na+ /K+ pump. In severely remodelled left atrium, with low voltage areas (LVA) covering more than 40% of the posterior wall, sustained AF requires higher IK1 and rotors localize in healthy right atrium. For lower LVA extensions, rotors can also anchor to LVA, if the atria present short refractoriness (low ICaL ) Vernakalant is effective in atria presenting long refractoriness (high ICaL ). For short refractoriness, atria with fast Na+ current (INa ) up-regulation respond more favourably to amiodarone than flecainide, and the opposite is found in atria with low INa . The inward currents (ICaL and INa ) are critical for optimal stratification of AF patient to pharmacological treatment and, together with the left atrial LVA extension, for accurately phenotyping AF dynamics.
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Affiliation(s)
- Albert Dasí
- Department of Computer ScienceUniversity of OxfordOxfordUK
| | - Michael T.B. Pope
- Department of CardiologyOxford University Hospitals NHS Foundation TrustOxfordUK
- Department for Human Development and HealthUniversity of SouthamptonSouthamptonUK
| | - Rohan S. Wijesurendra
- Department of CardiologyOxford University Hospitals NHS Foundation TrustOxfordUK
- Oxford Centre for Clinical Magnetic Resonance Research, Division of Cardiovascular Medicine, Radcliffe Department of MedicineUniversity of OxfordOxfordUK
| | - Tim R. Betts
- Department of CardiologyOxford University Hospitals NHS Foundation TrustOxfordUK
| | - Rafael Sachetto
- Departamento de Ciência da ComputaçãoUniversidade Federal de São João del‐ReiSão João del‐ReiBrazil
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7
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The role of β-adrenergic stimulation in QT interval adaptation to heart rate during stress test. PLoS One 2023; 18:e0280901. [PMID: 36701349 PMCID: PMC9879473 DOI: 10.1371/journal.pone.0280901] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2022] [Accepted: 01/10/2023] [Indexed: 01/27/2023] Open
Abstract
The adaptation lag of the QT interval after heart rate (HR) has been proposed as an arrhythmic risk marker. Most studies have quantified the QT adaptation lag in response to abrupt, step-like changes in HR induced by atrial pacing, in response to tilt test or during ambulatory recordings. Recent studies have introduced novel methods to quantify the QT adaptation lag to gradual, ramp-like HR changes in stress tests by evaluating the differences between the measured QT series and an estimated, memoryless QT series obtained from the instantaneous HR. These studies have observed the QT adaptation lag to progressively reduce when approaching the stress peak, with the underlying mechanisms being still unclear. This study analyzes the contribution of β-adrenergic stimulation to QT interval rate adaptation in response to gradual, ramp-like HR changes. We first quantify the QT adaptation lag in Coronary Artery Disease (CAD) patients undergoing stress test. To uncover the involved mechanisms, we use biophysically detailed computational models coupling descriptions of human ventricular electrophysiology and β-adrenergic signaling, from which we simulate ventricular action potentials and ECG signals. We characterize the adaptation of the simulated QT interval in response to the HR time series measured from each of the analyzed CAD patients. We show that, when the simulated ventricular tissue is subjected to a time-varying β-adrenergic stimulation pattern, with higher stimulation levels close to the stress peak, the simulated QT interval presents adaptation lags during exercise that are more similar to those measured from the patients than when subjected to constant β-adrenergic stimulation. During stress test recovery, constant and time-varying β-adrenergic stimulation patterns render similar adaptation lags, which are generally shorter than during exercise, in agreement with results from the patients. In conclusion, our findings support the role of time-varying β-adrenergic stimulation in contributing to QT interval adaptation to gradually increasing HR changes as those seen during the exercise phase of a stress test.
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8
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Zhang Y, Li Y, Thompson KN, Stoletov K, Yuan Q, Bera K, Lee SJ, Zhao R, Kiepas A, Wang Y, Mistriotis P, Serra SA, Lewis JD, Valverde MA, Martin SS, Sun SX, Konstantopoulos K. Polarized NHE1 and SWELL1 regulate migration direction, efficiency and metastasis. Nat Commun 2022; 13:6128. [PMID: 36253369 PMCID: PMC9576788 DOI: 10.1038/s41467-022-33683-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 09/26/2022] [Indexed: 12/24/2022] Open
Abstract
Cell migration regulates diverse (patho)physiological processes, including cancer metastasis. According to the Osmotic Engine Model, polarization of NHE1 at the leading edge of confined cells facilitates water uptake, cell protrusion and motility. The physiological relevance of the Osmotic Engine Model and the identity of molecules mediating cell rear shrinkage remain elusive. Here, we demonstrate that NHE1 and SWELL1 preferentially polarize at the cell leading and trailing edges, respectively, mediate cell volume regulation, cell dissemination from spheroids and confined migration. SWELL1 polarization confers migration direction and efficiency, as predicted mathematically and determined experimentally via optogenetic spatiotemporal regulation. Optogenetic RhoA activation at the cell front triggers SWELL1 re-distribution and migration direction reversal in SWELL1-expressing, but not SWELL1-knockdown, cells. Efficient cell reversal also requires Cdc42, which controls NHE1 repolarization. Dual NHE1/SWELL1 knockdown inhibits breast cancer cell extravasation and metastasis in vivo, thereby illustrating the physiological significance of the Osmotic Engine Model.
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Affiliation(s)
- Yuqi Zhang
- grid.21107.350000 0001 2171 9311Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, MD 21218 USA ,grid.21107.350000 0001 2171 9311Johns Hopkins Institute for NanoBioTechnology, The Johns Hopkins University, Baltimore, MD 21218 USA
| | - Yizeng Li
- grid.264260.40000 0001 2164 4508Department of Biomedical Engineering, Binghamton University, SUNY, Binghamton, NY 13902 USA
| | - Keyata N. Thompson
- grid.411024.20000 0001 2175 4264Marlene and Stewart Greenebaum National Cancer Institute Comprehensive Cancer Center, University of Maryland School of Medicine, Baltimore, MD 21201 USA
| | - Konstantin Stoletov
- grid.17089.370000 0001 2190 316XDepartment of Oncology, University of Alberta, Edmonton, AB T6G 2E1 Canada
| | - Qinling Yuan
- grid.21107.350000 0001 2171 9311Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, MD 21218 USA ,grid.21107.350000 0001 2171 9311Johns Hopkins Institute for NanoBioTechnology, The Johns Hopkins University, Baltimore, MD 21218 USA
| | - Kaustav Bera
- grid.21107.350000 0001 2171 9311Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, MD 21218 USA ,grid.21107.350000 0001 2171 9311Johns Hopkins Institute for NanoBioTechnology, The Johns Hopkins University, Baltimore, MD 21218 USA
| | - Se Jong Lee
- grid.21107.350000 0001 2171 9311Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, MD 21218 USA ,grid.21107.350000 0001 2171 9311Johns Hopkins Institute for NanoBioTechnology, The Johns Hopkins University, Baltimore, MD 21218 USA
| | - Runchen Zhao
- grid.21107.350000 0001 2171 9311Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, MD 21218 USA ,grid.21107.350000 0001 2171 9311Johns Hopkins Institute for NanoBioTechnology, The Johns Hopkins University, Baltimore, MD 21218 USA
| | - Alexander Kiepas
- grid.21107.350000 0001 2171 9311Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, MD 21218 USA ,grid.21107.350000 0001 2171 9311Johns Hopkins Institute for NanoBioTechnology, The Johns Hopkins University, Baltimore, MD 21218 USA
| | - Yao Wang
- grid.21107.350000 0001 2171 9311Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, MD 21218 USA ,grid.21107.350000 0001 2171 9311Johns Hopkins Institute for NanoBioTechnology, The Johns Hopkins University, Baltimore, MD 21218 USA
| | - Panagiotis Mistriotis
- grid.21107.350000 0001 2171 9311Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, MD 21218 USA ,grid.21107.350000 0001 2171 9311Johns Hopkins Institute for NanoBioTechnology, The Johns Hopkins University, Baltimore, MD 21218 USA ,grid.252546.20000 0001 2297 8753Department of Chemical Engineering, Auburn University, Auburn, AL 36849 USA
| | - Selma A. Serra
- grid.5612.00000 0001 2172 2676Laboratory of Molecular Physiology, Department of Experimental and Health Sciences, Universitat Pompeu Fabra, 08003 Barcelona, Spain
| | - John D. Lewis
- grid.17089.370000 0001 2190 316XDepartment of Oncology, University of Alberta, Edmonton, AB T6G 2E1 Canada
| | - Miguel A. Valverde
- grid.5612.00000 0001 2172 2676Laboratory of Molecular Physiology, Department of Experimental and Health Sciences, Universitat Pompeu Fabra, 08003 Barcelona, Spain
| | - Stuart S. Martin
- grid.411024.20000 0001 2175 4264Marlene and Stewart Greenebaum National Cancer Institute Comprehensive Cancer Center, University of Maryland School of Medicine, Baltimore, MD 21201 USA ,grid.411024.20000 0001 2175 4264Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201 USA
| | - Sean X. Sun
- grid.21107.350000 0001 2171 9311Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, MD 21218 USA ,grid.21107.350000 0001 2171 9311Johns Hopkins Institute for NanoBioTechnology, The Johns Hopkins University, Baltimore, MD 21218 USA ,grid.21107.350000 0001 2171 9311Department of Mechanical Engineering, The Johns Hopkins University, Baltimore, MD 21218 USA ,grid.21107.350000 0001 2171 9311Department of Biomedical Engineering, The Johns Hopkins University, Baltimore, MD 21218 USA
| | - Konstantinos Konstantopoulos
- grid.21107.350000 0001 2171 9311Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, MD 21218 USA ,grid.21107.350000 0001 2171 9311Johns Hopkins Institute for NanoBioTechnology, The Johns Hopkins University, Baltimore, MD 21218 USA ,grid.21107.350000 0001 2171 9311Department of Biomedical Engineering, The Johns Hopkins University, Baltimore, MD 21218 USA ,grid.21107.350000 0001 2171 9311Department of Oncology, The Johns Hopkins University, Baltimore, MD 21205 USA
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9
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Edenfield S, Sims AM, Porretta C, Gould HJ, Paul D. Effect of Cell Cycle on Cell Surface Expression of Voltage-Gated Sodium Channels and Na +,K +-ATPase. Cells 2022; 11:cells11203240. [PMID: 36291108 PMCID: PMC9600173 DOI: 10.3390/cells11203240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 10/11/2022] [Accepted: 10/12/2022] [Indexed: 11/25/2022] Open
Abstract
Voltage-gated sodium channels (VGSCs) are the target for many therapies. Variation in membrane potential occurs throughout the cell cycle, yet little attention has been devoted to the role of VGSCs and Na+,K+-ATPases. We hypothesized that in addition to doubling DNA and cell membrane in anticipation of cell division, there should be a doubling of VGSCs and Na+,K+-ATPase compared to non-dividing cells. We tested this hypothesis in eight immortalized cell lines by correlating immunocytofluorescent labeling of VGSCs or Na+,K+-ATPase with propidium iodide or DAPI fluorescence using flow cytometry and imaging. Cell surface expression of VGSCs during phases S through M was double that seen during phases G0–G1. By contrast, Na+,K+-ATPase expression increased only 1.5-fold. The increases were independent of baseline expression of channels or pumps. The variation in VGSC and Na+,K+-ATPase expression has implications for both our understanding of sodium’s role in controlling the cell cycle and variability of treatments targeted at these components of the Na+ handling system.
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Affiliation(s)
- Samantha Edenfield
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
| | - Abigail M. Sims
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
| | - Constance Porretta
- Department of Microbiology and Immunology, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Harry J. Gould
- Department of Neurology, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
- Department of Anesthesiology, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
- Neuroscience Center of Excellence, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
- Correspondence: (H.J.G.III); (D.P.)
| | - Dennis Paul
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
- Department of Neurology, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
- Department of Anesthesiology, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
- Neuroscience Center of Excellence, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
- Dental and Craniofacial Biology Center of Excellence, Louisiana State University Health Sciences Center, New Orleans, LA 70119, USA
- Correspondence: (H.J.G.III); (D.P.)
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10
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Syringic Acid Ameliorates Cardiac, Hepatic, Renal and Neuronal Damage Induced by Chronic Hyperglycaemia in Wistar Rats: A Behavioural, Biochemical and Histological Analysis. Molecules 2022; 27:molecules27196722. [PMID: 36235257 PMCID: PMC9573038 DOI: 10.3390/molecules27196722] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 09/29/2022] [Accepted: 10/04/2022] [Indexed: 11/16/2022] Open
Abstract
This study investigated the effects of syringic acid (SA) on renal, cardiac, hepatic, and neuronal diabetic complications in streptozotocin-induced neonatal (nSTZ) diabetic rats. STZ (110 mg/kg i.p) was injected into Wistar rat neonates as a split dose (second and third postnatal day). Diabetes mellitus was diagnosed in adults by measuring fasting blood glucose levels, urine volume, and food and water intake. The treatment of SA (25 mg/kg, 50 mg/kg p.o) was given from the 8th to 18th postnatal week. To assess the development of diabetic complications and the effect of therapy, biochemical indicators in serum and behavioural parameters were recorded at specific intervals during the study period. SA (25 mg/kg, 50 mg/kg p.o) treatment reduced hyperglycaemia, polydipsia, polyphagia, polyuria, relative organ weight, cardiac hypertrophic indices, inflammatory markers, cell injury markers, glycated haemoglobin, histopathological score, and oxidative stress, and increased Na/K ATPase activity. These findings suggest that SA might significantly alleviate diabetic complications and/or renal, neuronal, cardiac, and hepatic damage in nSTZ diabetic rats.
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11
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Adegoke TE, Sabinari IW, Usman TO, Abdulkareem TO, Michael OS, Adeyanju OA, Dibia C, Omotoye OO, Oyabambi AO, Olatunji LA. Allopurinol and valproic acid improve cardiac triglyceride and Na +-K +-ATPase activity independent of circulating aldosterone in female rats with glucose intolerance. Arch Physiol Biochem 2022; 128:1283-1289. [PMID: 32447998 DOI: 10.1080/13813455.2020.1767148] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Context: Studies have shown that cardiac triglyceride accumulation and impaired Na+-K+-ATPase activity are linked to diabetes- related cardiovascular disease, particularly in women.Objectives: We hypothesised that allopurinol (ALL) and valproic acid (VPA) treatment would improve cardiac triglyceride and Na+-K+-ATPase activity independent of circulating aldosterone in Combined Oral Contraceptive (COC)-induced dysglycemiaMaterials and methods: Rats received COC (1.0 μg ethinylestradiol and 5.0 μg levonorgestrel; po) with or without ALL (1 mg; po) and VPA (20 mg; po) for 6 weeks.Results: COC-treatment led to impaired glucose tolerance, accumulated abdominal fat, dyslipidemia, elevated plasma MDA, PAI-1 and aldosterone levels and also reduced plasma nitric oxide bioavailability and cardiac Na+-K+-ATPase activity. However, either ALL or VPA treatment ameliorated these alterations comparably independent of elevated aldosterone levelDiscussion and conclusion: Our results suggest that either ALL or VPA would improve cardiac TG and Na+-K+-ATPase activity comparably in COC-treated rats, regardless of circulating aldosterone level.
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Affiliation(s)
- Tolulope E Adegoke
- Department of Physiology, HOPE Cardiometabolic Research Team, College of Health Sciences, University of Ilorin, Ilorin, Nigeria
| | - Isiah W Sabinari
- Department of Physiology, HOPE Cardiometabolic Research Team, College of Health Sciences, University of Ilorin, Ilorin, Nigeria
| | - Taofeek O Usman
- Department of Physiology, HOPE Cardiometabolic Research Team, College of Health Sciences, University of Ilorin, Ilorin, Nigeria
- Department of Physiology, Cardiometabolic Research Unit, College of Health Sciences, Osun State University, Osogbo, Nigeria
| | - Toyyib O Abdulkareem
- Department of Physiology, HOPE Cardiometabolic Research Team, College of Health Sciences, University of Ilorin, Ilorin, Nigeria
| | - Olugbenga S Michael
- Department of Physiology, HOPE Cardiometabolic Research Team, College of Health Sciences, University of Ilorin, Ilorin, Nigeria
- Department of Physiology, Cardiometabolic Research Unit, College of Health and Medical Sciences, Bowen University, Iwo, Nigeria
| | - Oluwaseun A Adeyanju
- Department of Physiology, HOPE Cardiometabolic Research Team, College of Health Sciences, University of Ilorin, Ilorin, Nigeria
- Department of Physiology, Cardiometabolic Research Unit, College of Medicine and Health Sciences, Afe Babalola University, Ado-Ekiti, Nigeria
| | - Chinaza Dibia
- Department of Physiology, HOPE Cardiometabolic Research Team, College of Health Sciences, University of Ilorin, Ilorin, Nigeria
| | - Omotola O Omotoye
- Department of Physiology, HOPE Cardiometabolic Research Team, College of Health Sciences, University of Ilorin, Ilorin, Nigeria
| | - Adewumi O Oyabambi
- Department of Physiology, HOPE Cardiometabolic Research Team, College of Health Sciences, University of Ilorin, Ilorin, Nigeria
| | - Lawrence A Olatunji
- Department of Physiology, HOPE Cardiometabolic Research Team, College of Health Sciences, University of Ilorin, Ilorin, Nigeria
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Dasí A, Roy A, Sachetto R, Camps J, Bueno-Orovio A, Rodriguez B. In-silico drug trials for precision medicine in atrial fibrillation: From ionic mechanisms to electrocardiogram-based predictions in structurally-healthy human atria. Front Physiol 2022; 13:966046. [PMID: 36187798 PMCID: PMC9522526 DOI: 10.3389/fphys.2022.966046] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Accepted: 08/23/2022] [Indexed: 11/13/2022] Open
Abstract
Atrial fibrillation (AF) inducibility, sustainability and response to pharmacological treatment of individual patients are expected to be determined by their ionic current properties, especially in structurally-healthy atria. Mechanisms underlying AF and optimal cardioversion are however still unclear. In this study, in-silico drug trials were conducted using a population of human structurally-healthy atria models to 1) identify key ionic current properties determining AF inducibility, maintenance and pharmacological cardioversion, and 2) compare the prognostic value for predicting individual AF cardioversion of ionic current properties and electrocardiogram (ECG) metrics. In the population of structurally-healthy atria, 477 AF episodes were induced in ionic current profiles with both steep action potential duration (APD) restitution (eliciting APD alternans), and high excitability (enabling propagation at fast rates that transformed alternans into discordant). High excitability also favored 211 sustained AF episodes, so its decrease, through prolonged refractoriness, explained pharmacological cardioversion. In-silico trials over 200 AF episodes, 100 ionic profiles and 10 antiarrhythmic compounds were consistent with previous clinical trials, and identified optimal treatments for individual electrophysiological properties of the atria. Algorithms trained on 211 simulated AF episodes exhibited >70% accuracy in predictions of cardioversion for individual treatments using either ionic current profiles or ECG metrics. In structurally-healthy atria, AF inducibility and sustainability are enabled by discordant alternans, under high excitability and steep restitution conditions. Successful pharmacological cardioversion is predicted with 70% accuracy from either ionic or ECG properties, and it is optimal for treatments maximizing refractoriness (thus reducing excitability) for the given ionic current profile of the atria.
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Affiliation(s)
- Albert Dasí
- Department of Computer Science, University of Oxford, Oxford, United Kingdom,*Correspondence: Blanca Rodriguez, ; Albert Dasí,
| | - Aditi Roy
- Department of Computer Science, University of Oxford, Oxford, United Kingdom
| | - Rafael Sachetto
- Departamento de Ciência da Computação, Universidade Federal De São João Del-Rei, São João del Rei, Brazil
| | - Julia Camps
- Department of Computer Science, University of Oxford, Oxford, United Kingdom
| | | | - Blanca Rodriguez
- Department of Computer Science, University of Oxford, Oxford, United Kingdom,*Correspondence: Blanca Rodriguez, ; Albert Dasí,
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13
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Interpretable machine learning of action potential duration restitution kinetics in single-cell models of atrial cardiomyocytes. J Electrocardiol 2022; 74:137-145. [PMID: 36223672 DOI: 10.1016/j.jelectrocard.2022.09.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 08/28/2022] [Accepted: 09/19/2022] [Indexed: 12/13/2022]
Abstract
Action potential duration (APD) restitution curve and its maximal slope (Smax) reflect single cell-level dynamic instability for inducing chaotic heart rhythms. However, conventional parameter sensitivity analysis often fails to describe nonlinear relationships between ion channel parameters and electrophysiological phenotypes, such as Smax. We explored the parameter-phenotype mapping in a population of 5000 single-cell atrial cell models through interpretable machine learning (ML) approaches. Parameter sensitivity analyses could explain the linear relationships between parameters and electrophysiological phenotypes, including APD90, resting membrane potential, Vmax, refractory period, and APD/calcium alternans threshold, but not for Smax. However, neural network models had better prediction performance for Smax. To interpret the ML model, we evaluated the parameter importance at the global and local levels by computing the permutation feature importance and the local interpretable model-agnostic explanations (LIME) values, respectively. Increases in ICaL, INCX, and IKr, and decreases in IK1, Ib,Cl, IKur, ISERCA, and Ito are correlated with higher Smax values. The LIME algorithm determined that INaK plays a significant role in determining Smax as well as Ito and IKur. The atrial cardiomyocyte population was hierarchically clustered into three distinct groups based on the LIME values and the single-cell simulation confirmed that perturbations in INaK resulted in different behaviors of APD restitution curves in three clusters. Our combined top-down interpretable ML and bottom-up mechanistic simulation approaches uncovered the role of INaK in heterogeneous behaviors of Smax in the atrial cardiomyocyte population.
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14
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Abu Owida H, Al-Nabulsi JI, Alnaimat F, Al Sharah A, Al-Ayyad M, Turab NM, Abdullah M. Advancement of Nanofibrous Mats and Common Useful Drug Delivery Applications. Adv Pharmacol Pharm Sci 2022; 2022:9073837. [PMID: 35492808 PMCID: PMC9042622 DOI: 10.1155/2022/9073837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Revised: 02/15/2022] [Accepted: 04/07/2022] [Indexed: 11/18/2022] Open
Abstract
Electrospinning enables simple and cost-effective production of polymer nanofibers from different polymer materials. Drug delivery systems are capable of achieving maximum drug treatment benefits by significantly reducing adverse complications. Electrospun nanofibers have recently attracted considerable attention owing to their distinctive properties, including flexibility and biocompatibility. The implementation of functional constituents within nanostructure fibers blends is an effective technique for the administration of a variety of drugs in animal research, broadening the nanofiber capability and reliability. The nanofibrous mesh and its various application purposes are discussed in terms of a summary of recent research, emphasizing the ease of streaming and a large number of combinations of this approach, which could lead to a breakthrough in targeted therapy.
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Affiliation(s)
- Hamza Abu Owida
- Medical Engineering Department, Faculty of Engineering, Al-Ahliyya Amman University, Amman 19328, Jordan
| | - Jamal I. Al-Nabulsi
- Medical Engineering Department, Faculty of Engineering, Al-Ahliyya Amman University, Amman 19328, Jordan
| | - Feras Alnaimat
- Medical Engineering Department, Faculty of Engineering, Al-Ahliyya Amman University, Amman 19328, Jordan
| | - Ashraf Al Sharah
- Computer Engineering, Faculty of Engineering, Al-Ahliyya Amman University, Amman 19328, Jordan
| | - Muhammad Al-Ayyad
- Medical Engineering Department, Faculty of Engineering, Al-Ahliyya Amman University, Amman 19328, Jordan
| | - Nidal M. Turab
- Department of Networks and Information Security, Faculty of Information Technology, Al-Ahliyya Amman University, Amman 19328, Jordan
| | - Mustafa Abdullah
- Civil Engineering, Faculty of Engineering, Al-Ahliyya Amman University, Amman 19328, Jordan
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15
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Białek M, Białek A, Ruszczyńska A, Bulska E, Zaworski K, Czauderna M. Evaluation of the influence of diet supplementation with conjugated linoleic acid isomers on elemental composition in the cardio-oncological nutritional programming rat' model. J Trace Elem Med Biol 2021; 68:126816. [PMID: 34329902 DOI: 10.1016/j.jtemb.2021.126816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 05/17/2021] [Accepted: 07/03/2021] [Indexed: 10/20/2022]
Abstract
BACKGROUND The 'developmental origin of health and disease' (DOHaD) hypothesis assumes that due to the action of some stimuli during fetal life the long-term physiological changes occurs and may affects the risk of various diseases. The main aim of this study was to assess impact of supplementation of maternal' and early postnatal diet with conjugated linoleic acids (CLA) isomers on selected elements content in hearts of their female offspring with chemically induced breast cancer. METHODS Elemental composition was determined by quadrupole mass spectrometer with inductively coupled plasma ionization (ICP-MS). RESULTS The effect of maternal' diet on the elements content was more pronounced than the progeny diet modifications. Significant correlations among determined elements, especially macroelements, and lipidomic parameters, in the experimental factors dependent manner were observed. It can be concluded that supplementation of maternal and progeny diets with CLA isomers may significantly influence the contents of both macro- and microelements in cardiac tissue of newborns. CONCLUSION Our results also indicate, that dynamic and intricate balance among various elements in body may be affected by the lipid dietary supplements also in the pathological state. Utility of cardio-oncological approach in developmental programming study was confirmed.
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Affiliation(s)
- Małgorzata Białek
- The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences, Instytucka 3, 05-110 Jabłonna, Poland.
| | - Agnieszka Białek
- Department of Biotechnology and Nutrigenomics, Institute of Genetics and Animal Biotechnology of Polish Academy of Sciences, Postępu 36A Jastrzębiec, 05-552 Magdalenka, Poland
| | - Anna Ruszczyńska
- Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Żwirki i Wigury 101, 02-089 Warsaw, Poland
| | - Ewa Bulska
- Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Żwirki i Wigury 101, 02-089 Warsaw, Poland
| | - Kamil Zaworski
- The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences, Instytucka 3, 05-110 Jabłonna, Poland
| | - Marian Czauderna
- The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences, Instytucka 3, 05-110 Jabłonna, Poland
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16
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Tóth N, Soós A, Váradi A, Hegyi P, Tinusz B, Vágvölgyi A, Orosz A, Solymár M, Polyák A, Varró A, Farkas AS, Nagy N. Effect of ivabradine in heart failure: a meta-analysis of heart failure patients with reduced versus preserved ejection fraction. Can J Physiol Pharmacol 2021; 99:1159-1174. [PMID: 34636643 DOI: 10.1139/cjpp-2020-0700] [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: 11/22/2022]
Abstract
In clinical trials of heart failure reduced ejection fraction (HFrEF), ivabradine seemed to be an effective heart rate lowering agent associated with lower risk of cardiovascular death. In contrast, ivabradine failed to improve cardiovascular outcomes in heart failure preserved ejection fraction (HFpEF) despite the significant effect on heart rate. This meta-analysis is the first to compare the effects of ivabradine on heart rate and mortality parameters in HFpEF versus HFrEF. We screened three databases: PubMed, Embase, and Cochrane Library. The outcomes of these studies were mortality, reduction in heart rate, and left ventricular function improvement. We compared the efficacy of ivabradine treatment in HFpEF versus HFrEF. Heart rate analysis of pooled data showed decrease in both HFrEF (-17.646 beats/min) and HFpEF (-11.434 beats/min), and a tendency to have stronger bradycardic effect in HFrEF (p = 0.094) in randomized clinical trials. Left ventricular ejection fraction analysis revealed significant improvement in HFrEF (5.936, 95% CI: [4.199-7.672], p < 0.001) when compared with placebo (p < 0.001). We found that ivabradine significantly improves left ventricular performance in HFrEF, at the same time it exerts a tendency to have improved bradycardic effect in HFrEF. These disparate effects of ivabradine and the higher prevalence of non-cardiac comorbidities in HFpEF may explain the observed beneficial effects in HFrEF and the unchanged outcomes in HFpEF patients after ivabradine treatment.
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Affiliation(s)
- Noémi Tóth
- Department of Pharmacology and Pharmacotherapy, Albert Szent-Györgyi Medical School University of Szeged, Dóm Square 12, Szeged 6720, Hungary
| | - Alexandra Soós
- Institute for Translational Medicine, Medical School, University of Pécs, 12 Szigeti Street, Pécs 7624, Hungary
| | - Alex Váradi
- Institute for Translational Medicine, Medical School, University of Pécs, 12 Szigeti Street, Pécs 7624, Hungary
| | - Péter Hegyi
- Institute for Translational Medicine, Medical School, University of Pécs, 12 Szigeti Street, Pécs 7624, Hungary
| | - Benedek Tinusz
- Institute for Translational Medicine, Medical School, University of Pécs, 12 Szigeti Street, Pécs 7624, Hungary.,First Department of Medicine, Medical School, University of Pécs, Ifjúság Street 13, Pécs 7624, Hungary
| | - Anna Vágvölgyi
- Department of Internal Medicine, Albert Szent-Györgyi Medical School University of Szeged, Kálvária sgt. 57, Szeged 6720, Hungary
| | - Andrea Orosz
- Department of Pharmacology and Pharmacotherapy, Albert Szent-Györgyi Medical School University of Szeged, Dóm Square 12, Szeged 6720, Hungary
| | - Margit Solymár
- Institute for Translational Medicine, Medical School, University of Pécs, 12 Szigeti Street, Pécs 7624, Hungary
| | - Alexandra Polyák
- Department of Internal Medicine, Albert Szent-Györgyi Medical School University of Szeged, Kálvária sgt. 57, Szeged 6720, Hungary
| | - András Varró
- Department of Pharmacology and Pharmacotherapy, Albert Szent-Györgyi Medical School University of Szeged, Dóm Square 12, Szeged 6720, Hungary.,ELKH-SZTE Research Group of Cardiovascular Pharmacology, Szeged, Hungary
| | - Attila S Farkas
- Department of Internal Medicine, Albert Szent-Györgyi Medical School University of Szeged, Kálvária sgt. 57, Szeged 6720, Hungary
| | - Norbert Nagy
- Department of Pharmacology and Pharmacotherapy, Albert Szent-Györgyi Medical School University of Szeged, Dóm Square 12, Szeged 6720, Hungary.,ELKH-SZTE Research Group of Cardiovascular Pharmacology, Szeged, Hungary
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17
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Li Y, Zhou X, Sun SX. Hydrogen, Bicarbonate, and Their Associated Exchangers in Cell Volume Regulation. Front Cell Dev Biol 2021; 9:683686. [PMID: 34249935 PMCID: PMC8264760 DOI: 10.3389/fcell.2021.683686] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Accepted: 05/31/2021] [Indexed: 11/25/2022] Open
Abstract
Cells lacking a stiff cell wall, e.g., mammalian cells, must actively regulate their volume to maintain proper cell function. On the time scale that protein production is negligible, water flow in and out of the cell determines the cell volume variation. Water flux follows hydraulic and osmotic gradients; the latter is generated by various ion channels, transporters, and pumps in the cell membrane. Compared to the widely studied roles of sodium, potassium, and chloride in cell volume regulation, the effects of proton and bicarbonate are less understood. In this work, we use mathematical models to analyze how proton and bicarbonate, combined with sodium, potassium, chloride, and buffer species, regulate cell volume upon inhibition of ion channels, transporters, and pumps. The model includes several common, widely expressed ion transporters and focuses on obtaining generic outcomes. Results show that the intracellular osmolarity remains almost constant before and after cell volume change. The steady-state cell volume does not depend on water permeability. In addition, to ensure the stability of cell volume and ion concentrations, cells need to develop redundant mechanisms to maintain homeostasis, i.e., multiple ion channels or transporters are involved in the flux of the same ion species. These results provide insights for molecular mechanisms of cell volume regulation with additional implications for water-driven cell migration.
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Affiliation(s)
- Yizeng Li
- Department of Mechanical Engineering, Kennesaw State University, Marietta, GA, United States
| | - Xiaohan Zhou
- Department of Physics, University of Toronto, Toronto, ON, Canada
| | - Sean X. Sun
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD, United States
- Institute for NanoBioTechnology, Johns Hopkins University, Baltimore, MD, United States
- Center for Cell Dynamics, Johns Hopkins School of Medicine, Baltimore, MD, United States
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18
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Luraghi A, Peri F, Moroni L. Electrospinning for drug delivery applications: A review. J Control Release 2021; 334:463-484. [PMID: 33781809 DOI: 10.1016/j.jconrel.2021.03.033] [Citation(s) in RCA: 236] [Impact Index Per Article: 78.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Revised: 03/23/2021] [Accepted: 03/24/2021] [Indexed: 12/20/2022]
Abstract
Drug delivery devices are promising tools in the pharmaceutical field, as they are able to maximize the therapeutic effects of the delivered drug while minimizing the undesired side effects. In the past years, electrospun nanofibers attracted rising attention due to their unique features, like biocompatibility and broad flexibility. Incorporation of active principles in nanofibrous meshes proved to be an efficient method for in situ delivery of a wide range of drugs, expanding the possibility and applicability of those devices. In this review, the principle of electrospinning and different fields of applications are treated to give an overview of the recent literature, underlining the easy tuning and endless combination of this technique, that in the future could be the new frontier of personalized medicine.
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Affiliation(s)
- Andrea Luraghi
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza, 2, 20126 Milan, Italy
| | - Francesco Peri
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza, 2, 20126 Milan, Italy
| | - Lorenzo Moroni
- Complex Tissue Regeneration Department, MERLN Institute for Technology-Inspired Regenerative Medicine, Maastricht University, Universiteitssingel 40, 6229 ET Maastricht, the Netherlands.
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19
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Yan J, Sun B, Xie C, Liu Y, Song Z, Xu H, Wang Z. The influence of different liquid environments on the atomic force microscopy detection of living bEnd.3 cells. ANALYTICAL METHODS : ADVANCING METHODS AND APPLICATIONS 2021; 13:2384-2390. [PMID: 33970977 DOI: 10.1039/d1ay00567g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Atomic force microscopy (AFM) is one of the most important tools in the field of biomedical science, and it can be used to perform the high-resolution three-dimensional imaging of samples in liquid environments to obtain their physical properties (such as surface potentials and mechanical properties). The influence of the liquid environment on the image quality of the sample and the detection results cannot be ignored. In this work, quantitative imaging (QI) mode AFM imaging and mechanical detection were performed on mouse brain microvascular endothelial (bEnd.3) cells in different liquid environments. The gray-level variance product (SMD2) function was used to evaluate the imaging quality of the cells in liquids with different physical properties, and the variations in cell mechanical properties were quantitatively analyzed. An AFM detection liquid containing less ions and organics compared with the traditional culture medium, which is beneficial for improving the imaging quality, is introduced, and it shows similar mechanical detection results within 3 h. This can greatly reduce the detection costs and could have positive significance in the field of AFM living-cell detection.
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Affiliation(s)
- Jin Yan
- International Research Centre for Nano Handling and Manufacturing of China, Changchun University of Science and Technology, Changchun 130022, China.
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20
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Clerx M, Mirams GR, Rogers AJ, Narayan SM, Giles WR. Immediate and Delayed Response of Simulated Human Atrial Myocytes to Clinically-Relevant Hypokalemia. Front Physiol 2021; 12:651162. [PMID: 34122128 PMCID: PMC8188899 DOI: 10.3389/fphys.2021.651162] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 03/22/2021] [Indexed: 12/18/2022] Open
Abstract
Although plasma electrolyte levels are quickly and precisely regulated in the mammalian cardiovascular system, even small transient changes in K+, Na+, Ca2+, and/or Mg2+ can significantly alter physiological responses in the heart, blood vessels, and intrinsic (intracardiac) autonomic nervous system. We have used mathematical models of the human atrial action potential (AP) to explore the electrophysiological mechanisms that underlie changes in resting potential (Vr) and the AP following decreases in plasma K+, [K+]o, that were selected to mimic clinical hypokalemia. Such changes may be associated with arrhythmias and are commonly encountered in patients (i) in therapy for hypertension and heart failure; (ii) undergoing renal dialysis; (iii) with any disease with acid-base imbalance; or (iv) post-operatively. Our study emphasizes clinically-relevant hypokalemic conditions, corresponding to [K+]o reductions of approximately 1.5 mM from the normal value of 4 to 4.5 mM. We show how the resulting electrophysiological responses in human atrial myocytes progress within two distinct time frames: (i) Immediately after [K+]o is reduced, the K+-sensing mechanism of the background inward rectifier current (IK1) responds. Specifically, its highly non-linear current-voltage relationship changes significantly as judged by the voltage dependence of its region of outward current. This rapidly alters, and sometimes even depolarizes, Vr and can also markedly prolong the final repolarization phase of the AP, thus modulating excitability and refractoriness. (ii) A second much slower electrophysiological response (developing 5-10 minutes after [K+]o is reduced) results from alterations in the intracellular electrolyte balance. A progressive shift in intracellular [Na+]i causes a change in the outward electrogenic current generated by the Na+/K+ pump, thereby modifying Vr and AP repolarization and changing the human atrial electrophysiological substrate. In this study, these two effects were investigated quantitatively, using seven published models of the human atrial AP. This highlighted the important role of IK1 rectification when analyzing both the mechanisms by which [K+]o regulates Vr and how the AP waveform may contribute to "trigger" mechanisms within the proarrhythmic substrate. Our simulations complement and extend previous studies aimed at understanding key factors by which decreases in [K+]o can produce effects that are known to promote atrial arrhythmias in human hearts.
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Affiliation(s)
- Michael Clerx
- Centre for Mathematical Medicine and Biology, School of Mathematical Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Gary R Mirams
- Centre for Mathematical Medicine and Biology, School of Mathematical Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Albert J Rogers
- Department of Medicine and Cardiovascular Institute, Stanford University, Stanford, CA, United States
| | - Sanjiv M Narayan
- Department of Medicine and Cardiovascular Institute, Stanford University, Stanford, CA, United States
| | - Wayne R Giles
- Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada
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21
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Simple models including energy and spike constraints reproduce complex activity patterns and metabolic disruptions. PLoS Comput Biol 2020; 16:e1008503. [PMID: 33347433 PMCID: PMC7785241 DOI: 10.1371/journal.pcbi.1008503] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 01/05/2021] [Accepted: 11/09/2020] [Indexed: 12/23/2022] Open
Abstract
In this work, we introduce new phenomenological neuronal models (eLIF and mAdExp) that account for energy supply and demand in the cell as well as the inactivation of spike generation how these interact with subthreshold and spiking dynamics. Including these constraints, the new models reproduce a broad range of biologically-relevant behaviors that are identified to be crucial in many neurological disorders, but were not captured by commonly used phenomenological models. Because of their low dimensionality eLIF and mAdExp open the possibility of future large-scale simulations for more realistic studies of brain circuits involved in neuronal disorders. The new models enable both more accurate modeling and the possibility to study energy-associated disorders over the whole time-course of disease progression instead of only comparing the initially healthy status with the final diseased state. These models, therefore, provide new theoretical and computational methods to assess the opportunities of early diagnostics and the potential of energy-centered approaches to improve therapies. Neurons, even “at rest”, require a constant supply of energy to function. They cannot sustain high-frequency activity over long periods because of regulatory mechanisms, such as adaptation or sodium channels inactivation, and metabolic limitations. These limitations are especially severe in many neuronal disorders, where energy can become insufficient and make the neuronal response change drastically, leading to increased burstiness, network oscillations, or seizures. Capturing such behaviors and impact of energy constraints on them is an essential prerequisite to study disorders such as Parkinson’s disease and epilepsy. However, energy and spiking constraints are not present in any of the standard neuronal models used in computational neuroscience. Here we introduce models that provide a simple and scalable way to account for these features, enabling large-scale theoretical and computational studies of neurological disorders and activity patterns that could not be captured by previously used models. These models provide a way to study energy-associated disorders over the whole time-course of disease progression, and they enable a better assessment of energy-centered approaches to improve therapies.
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22
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Varró A, Tomek J, Nagy N, Virág L, Passini E, Rodriguez B, Baczkó I. Cardiac transmembrane ion channels and action potentials: cellular physiology and arrhythmogenic behavior. Physiol Rev 2020; 101:1083-1176. [PMID: 33118864 DOI: 10.1152/physrev.00024.2019] [Citation(s) in RCA: 86] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Cardiac arrhythmias are among the leading causes of mortality. They often arise from alterations in the electrophysiological properties of cardiac cells and their underlying ionic mechanisms. It is therefore critical to further unravel the pathophysiology of the ionic basis of human cardiac electrophysiology in health and disease. In the first part of this review, current knowledge on the differences in ion channel expression and properties of the ionic processes that determine the morphology and properties of cardiac action potentials and calcium dynamics from cardiomyocytes in different regions of the heart are described. Then the cellular mechanisms promoting arrhythmias in congenital or acquired conditions of ion channel function (electrical remodeling) are discussed. The focus is on human-relevant findings obtained with clinical, experimental, and computational studies, given that interspecies differences make the extrapolation from animal experiments to human clinical settings difficult. Deepening the understanding of the diverse pathophysiology of human cellular electrophysiology will help in developing novel and effective antiarrhythmic strategies for specific subpopulations and disease conditions.
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Affiliation(s)
- András Varró
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary.,MTA-SZTE Cardiovascular Pharmacology Research Group, Hungarian Academy of Sciences, Szeged, Hungary
| | - Jakub Tomek
- Department of Computer Science, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Norbert Nagy
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary.,MTA-SZTE Cardiovascular Pharmacology Research Group, Hungarian Academy of Sciences, Szeged, Hungary
| | - László Virág
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Elisa Passini
- Department of Computer Science, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Blanca Rodriguez
- Department of Computer Science, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - István Baczkó
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
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Sghari S, Davies WIL, Gunhaga L. Elucidation of Cellular Mechanisms That Regulate the Sustained Contraction and Relaxation of the Mammalian Iris. Invest Ophthalmol Vis Sci 2020; 61:5. [PMID: 32882011 PMCID: PMC7476664 DOI: 10.1167/iovs.61.11.5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 08/19/2020] [Indexed: 12/15/2022] Open
Abstract
Purpose In mammals, pupil constriction and dilation form the pupillary light reflex (PLR), which is mediated by both brain-regulated (parasympathetic) and local iris-driven reflexes. To better understand the cellular mechanisms that regulate pupil physiological dynamics via central and local photoreception, we have examined the regulation of the PLR via parasympathetic and local activation, respectively. Methods In this study, the PLR was examined in mouse enucleated eyes ex vivo in real-time under different ionic conditions in response to acetylcholine and/or blue light (480 nm). The use of pupillometry recordings captured the relaxation, contraction, and pupil escape (redilation) processes for 10 minutes up to 1 hour. Results Among others, our results show that ryanodine receptor channels are the main driver for iridal stimulation-contraction coupling, in which extracellular influx of Ca2+ is required for amplification of pupil constriction. Both local and parasympathetic iridal activations are necessary, but not sufficient for sustained pupil constriction. Moreover, the degree of membrane potential repolarization in the dark is correlated with the latency and velocity of iridal constriction. Furthermore, pupil escape is driven by membrane potential hyperpolarization where voltage-gated potassium channels play a crucial role. Conclusions Together, this study presents new mechanisms regulating synchronized pupil dilation and contraction, sustained pupil constriction, iridal stimulation-contraction coupling, and pupil escape.
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Affiliation(s)
- Soufien Sghari
- Umeå Centre for Molecular Medicine (UCMM), Umeå University, Umeå, Sweden
| | - Wayne I. L. Davies
- Umeå Centre for Molecular Medicine (UCMM), Umeå University, Umeå, Sweden
| | - Lena Gunhaga
- Umeå Centre for Molecular Medicine (UCMM), Umeå University, Umeå, Sweden
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Whittaker DG, Clerx M, Lei CL, Christini DJ, Mirams GR. Calibration of ionic and cellular cardiac electrophysiology models. WILEY INTERDISCIPLINARY REVIEWS. SYSTEMS BIOLOGY AND MEDICINE 2020; 12:e1482. [PMID: 32084308 PMCID: PMC8614115 DOI: 10.1002/wsbm.1482] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 01/17/2020] [Accepted: 01/18/2020] [Indexed: 12/30/2022]
Abstract
Cardiac electrophysiology models are among the most mature and well-studied mathematical models of biological systems. This maturity is bringing new challenges as models are being used increasingly to make quantitative rather than qualitative predictions. As such, calibrating the parameters within ion current and action potential (AP) models to experimental data sets is a crucial step in constructing a predictive model. This review highlights some of the fundamental concepts in cardiac model calibration and is intended to be readily understood by computational and mathematical modelers working in other fields of biology. We discuss the classic and latest approaches to calibration in the electrophysiology field, at both the ion channel and cellular AP scales. We end with a discussion of the many challenges that work to date has raised and the need for reproducible descriptions of the calibration process to enable models to be recalibrated to new data sets and built upon for new studies. This article is categorized under: Analytical and Computational Methods > Computational Methods Physiology > Mammalian Physiology in Health and Disease Models of Systems Properties and Processes > Cellular Models.
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Affiliation(s)
- Dominic G. Whittaker
- Centre for Mathematical Medicine & Biology, School of Mathematical SciencesUniversity of NottinghamNottinghamUK
| | - Michael Clerx
- Computational Biology & Health Informatics, Department of Computer ScienceUniversity of OxfordOxfordUK
| | - Chon Lok Lei
- Computational Biology & Health Informatics, Department of Computer ScienceUniversity of OxfordOxfordUK
| | | | - Gary R. Mirams
- Centre for Mathematical Medicine & Biology, School of Mathematical SciencesUniversity of NottinghamNottinghamUK
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25
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Şengül Ayan S, Sırcan AK, Abewa M, Kurt A, Dalaman U, Yaraş N. Mathematical model of the ventricular action potential and effects of isoproterenol-induced cardiac hypertrophy in rats. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2020; 49:323-342. [PMID: 32462262 DOI: 10.1007/s00249-020-01439-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 04/21/2020] [Accepted: 05/17/2020] [Indexed: 12/16/2022]
Abstract
Mathematical action potential (AP) modeling is a well-established but still-developing area of research to better understand physiological and pathological processes. In particular, changes in AP mechanisms in the isoproterenol (ISO) -induced hypertrophic heart model are incompletely understood. Here we present a mathematical model of the rat AP based on recordings from rat ventricular myocytes. In our model, for the first time, all channel kinetics are defined with a single type of function that is simple and easy to apply. The model AP and channels dynamics are consistent with the APs recorded from rats for both Control (absence of ISO) and ISO-treated cases. Our mathematical model helps us to understand the reason for the prolongation in AP duration after ISO application while ISO treatment helps us to validate our mathematical model. We reveal that the smaller density and the slower gating kinetics of the transient K+ current help explain the prolonged AP duration after ISO treatment and the increasing amplitude of the rapid and the slow inward rectifier currents also contribute to this prolongation alongside the flux in Ca2+ currents. ISO induced an increase in the density of the Na+ current that can explain the faster upstroke. We believe that AP dynamics from rat ventricular myocytes can be reproduced very well with this mathematical model and that it provides a powerful tool for improved insights into the underlying dynamics of clinically important AP properties such as ISO application.
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Affiliation(s)
- Sevgi Şengül Ayan
- Department of Engineering, Industrial Engineering, Antalya Bilim University, Döşemealtı, Antalya, Turkey.
| | - Ahmet K Sırcan
- Department of Engineering, Electrical and Computer Engineering, Antalya Bilim University, Döşemealtı, Antalya, Turkey
| | - Mohamedou Abewa
- Department of Engineering, Electrical and Computer Engineering, Antalya Bilim University, Döşemealtı, Antalya, Turkey
| | - Ahmet Kurt
- Department of Engineering, Electrical and Computer Engineering, Florida International University, Miami, USA
| | - Uğur Dalaman
- Department of Biophysics, Akdeniz University College of Medicine, Akdeniz University, Antalya, Turkey
| | - Nazmi Yaraş
- Department of Biophysics, Akdeniz University College of Medicine, Akdeniz University, Antalya, Turkey
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26
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Medrano-Soto A, Ghazi F, Hendargo KJ, Moreno-Hagelsieb G, Myers S, Saier MH. Expansion of the Transporter-Opsin-G protein-coupled receptor superfamily with five new protein families. PLoS One 2020; 15:e0231085. [PMID: 32320418 PMCID: PMC7176098 DOI: 10.1371/journal.pone.0231085] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Accepted: 03/17/2020] [Indexed: 02/06/2023] Open
Abstract
Here we provide bioinformatic evidence that the Organo-Arsenical Exporter (ArsP), Endoplasmic Reticulum Retention Receptor (KDELR), Mitochondrial Pyruvate Carrier (MPC), L-Alanine Exporter (AlaE), and the Lipid-linked Sugar Translocase (LST) protein families are members of the Transporter-Opsin-G Protein-coupled Receptor (TOG) Superfamily. These families share domains homologous to well-established TOG superfamily members, and their topologies of transmembranal segments (TMSs) are compatible with the basic 4-TMS repeat unit characteristic of this Superfamily. These repeat units tend to occur twice in proteins as a result of intragenic duplication events, often with subsequent gain/loss of TMSs in many superfamily members. Transporters within the ArsP family allow microbial pathogens to expel toxic arsenic compounds from the cell. Members of the KDELR family are involved in the selective retrieval of proteins that reside in the endoplasmic reticulum. Proteins of the MPC family are involved in the transport of pyruvate into mitochondria, providing the organelle with a major oxidative fuel. Members of family AlaE excrete L-alanine from the cell. Members of the LST family are involved in the translocation of lipid-linked glucose across the membrane. These five families substantially expand the range of substrates of transport carriers in the superfamily, although KDEL receptors have no known transport function. Clustering of protein sequences reveals the relationships among families, and the resulting tree correlates well with the degrees of sequence similarity documented between families. The analyses and programs developed to detect distant relatedness, provide insights into the structural, functional, and evolutionary relationships that exist between families of the TOG superfamily, and should be of value to many other investigators.
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Affiliation(s)
- Arturo Medrano-Soto
- Department of Molecular Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, California, United States of America
| | - Faezeh Ghazi
- Department of Molecular Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, California, United States of America
| | - Kevin J. Hendargo
- Department of Molecular Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, California, United States of America
| | | | - Scott Myers
- Department of Molecular Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, California, United States of America
| | - Milton H. Saier
- Department of Molecular Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, California, United States of America
- * E-mail:
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27
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Ni H, Morotti S, Grandi E. A Heart for Diversity: Simulating Variability in Cardiac Arrhythmia Research. Front Physiol 2018; 9:958. [PMID: 30079031 PMCID: PMC6062641 DOI: 10.3389/fphys.2018.00958] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 06/29/2018] [Indexed: 12/31/2022] Open
Abstract
In cardiac electrophysiology, there exist many sources of inter- and intra-personal variability. These include variability in conditions and environment, and genotypic and molecular diversity, including differences in expression and behavior of ion channels and transporters, which lead to phenotypic diversity (e.g., variable integrated responses at the cell, tissue, and organ levels). These variabilities play an important role in progression of heart disease and arrhythmia syndromes and outcomes of therapeutic interventions. Yet, the traditional in silico framework for investigating cardiac arrhythmias is built upon a parameter/property-averaging approach that typically overlooks the physiological diversity. Inspired by work done in genetics and neuroscience, new modeling frameworks of cardiac electrophysiology have been recently developed that take advantage of modern computational capabilities and approaches, and account for the variance in the biological data they are intended to illuminate. In this review, we outline the recent advances in statistical and computational techniques that take into account physiological variability, and move beyond the traditional cardiac model-building scheme that involves averaging over samples from many individuals in the construction of a highly tuned composite model. We discuss how these advanced methods have harnessed the power of big (simulated) data to study the mechanisms of cardiac arrhythmias, with a special emphasis on atrial fibrillation, and improve the assessment of proarrhythmic risk and drug response. The challenges of using in silico approaches with variability are also addressed and future directions are proposed.
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Affiliation(s)
| | | | - Eleonora Grandi
- Department of Pharmacology, University of California, Davis, Davis, CA, United States
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28
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Reproducible model development in the cardiac electrophysiology Web Lab. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2018; 139:3-14. [PMID: 29842853 PMCID: PMC6288479 DOI: 10.1016/j.pbiomolbio.2018.05.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 05/01/2018] [Accepted: 05/23/2018] [Indexed: 12/18/2022]
Abstract
The modelling of the electrophysiology of cardiac cells is one of the most mature areas of systems biology. This extended concentration of research effort brings with it new challenges, foremost among which is that of choosing which of these models is most suitable for addressing a particular scientific question. In a previous paper, we presented our initial work in developing an online resource for the characterisation and comparison of electrophysiological cell models in a wide range of experimental scenarios. In that work, we described how we had developed a novel protocol language that allowed us to separate the details of the mathematical model (the majority of cardiac cell models take the form of ordinary differential equations) from the experimental protocol being simulated. We developed a fully-open online repository (which we termed the Cardiac Electrophysiology Web Lab) which allows users to store and compare the results of applying the same experimental protocol to competing models. In the current paper we describe the most recent and planned extensions of this work, focused on supporting the process of model building from experimental data. We outline the necessary work to develop a machine-readable language to describe the process of inferring parameters from wet lab datasets, and illustrate our approach through a detailed example of fitting a model of the hERG channel using experimental data. We conclude by discussing the future challenges in making further progress in this domain towards our goal of facilitating a fully reproducible approach to the development of cardiac cell models.
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29
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Yellin F, Li Y, Sreenivasan VKA, Farrell B, Johny MB, Yue D, Sun SX. Electromechanics and Volume Dynamics in Nonexcitable Tissue Cells. Biophys J 2018; 114:2231-2242. [PMID: 29742416 PMCID: PMC5961520 DOI: 10.1016/j.bpj.2018.03.033] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 03/21/2018] [Accepted: 03/23/2018] [Indexed: 02/01/2023] Open
Abstract
Cell volume regulation is fundamentally important in phenomena such as cell growth, proliferation, tissue homeostasis, and embryogenesis. How the cell size is set, maintained, and changed over a cell's lifetime is not well understood. In this work we focus on how the volume of nonexcitable tissue cells is coupled to the cell membrane electrical potential and the concentrations of membrane-permeable ions in the cell environment. Specifically, we demonstrate that a sudden cell depolarization using the whole-cell patch clamp results in a 50% increase in cell volume, whereas hyperpolarization results in a slight volume decrease. We find that cell volume can be partially controlled by changing the chloride or the sodium/potassium concentrations in the extracellular environment while maintaining a constant external osmotic pressure. Depletion of external chloride leads to a volume decrease in suspended HN31 cells. Introducing cells to a high-potassium solution causes volume increase up to 50%. Cell volume is also influenced by cortical tension: actin depolymerization leads to cell volume increase. We present an electrophysiology model of water dynamics driven by changes in membrane potential and the concentrations of permeable ions in the cells surrounding. The model quantitatively predicts that the cell volume is directly proportional to the intracellular protein content.
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Affiliation(s)
- Florence Yellin
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, Maryland
| | - Yizeng Li
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, Maryland
| | | | - Brenda Farrell
- Otolaryngology-Head and Neck Surgery, Baylor College of Medicine, Houston, Texas
| | - Manu B Johny
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland
| | - David Yue
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland
| | - Sean X Sun
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, Maryland; Institute of NanoBioTechnology, Johns Hopkins University, Baltimore, Maryland; Johns Hopkins Physical Sciences-Oncology Center, Johns Hopkins University, Baltimore, Maryland.
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30
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Fernandez-Chas M, Curtis MJ, Niederer SA. Mechanism of doxorubicin cardiotoxicity evaluated by integrating multiple molecular effects into a biophysical model. Br J Pharmacol 2018; 175:763-781. [PMID: 29161764 DOI: 10.1111/bph.14104] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 10/20/2017] [Accepted: 10/23/2017] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE Doxorubicin (DOX) is an effective cancer therapeutic agent but causes therapy-limiting cardiotoxicity. The effects of DOX and its metabolite doxorubicinol (DOXL) on individual channels have been well characterized in isolation. However, it is unknown how the action and interaction of affected channels combine to generate the phenotypic cardiotoxic outcome. We sought to develop an in silico model that links drug effects on channels to action potential duration (APD) and intracellular Ca2+ concentration in order to address this gap in knowledge. EXPERIMENTAL APPROACH We first propose two methods to obtain, from published values, consensus drug effects on the currents of individual channels, transporters and pumps. Separately, we obtained equivalent values for APD and Ca2+ concentration (the readouts used as surrogates for cardiotoxicity). Once derived, the consensus effects on the currents were incorporated into established biophysical models of the cardiac myocyte and were refined adjusting the sarcoplasmic reticulum Ca2+ leak current (ILeak ) until the consensus effects on APD and Ca2+ dynamics were replicated. Using factorial analysis, we then quantified the relative contribution of each channel to DOX and DOXL cardiotoxicity. KEY RESULTS The factorial analysis identified the rapid delayed rectifying K+ current, the L-type Ca2+ current and the sarcoplasmic reticulum ILeak as the targets primarily responsible for the cardiotoxic effects on APD and Ca2+ dynamics. CONCLUSIONS AND IMPLICATIONS This study provides insight into the mechanisms of DOX-induced cardiotoxicity and a framework for the development of future diagnostic and therapeutic strategies.
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Affiliation(s)
- M Fernandez-Chas
- Division of Imaging Sciences and Biomedical Engineering (MF, SAN) and Cardiovascular Division (MJC), King's College London, London, UK
| | - M J Curtis
- Division of Imaging Sciences and Biomedical Engineering (MF, SAN) and Cardiovascular Division (MJC), King's College London, London, UK
| | - S A Niederer
- Division of Imaging Sciences and Biomedical Engineering (MF, SAN) and Cardiovascular Division (MJC), King's College London, London, UK
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Hanson BM, Gill JS, Taggart P, Rodriguez B, Bueno-Orovio A. Slow Adaptation of Ventricular Repolarization as a Cause of Arrhythmia? Methods Inf Med 2018; 53:320-3. [DOI: 10.3414/me13-02-0039] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Accepted: 02/12/2014] [Indexed: 11/09/2022]
Abstract
SummaryIntroduction: This article is part of the Focus Theme of Methods of Information in Medicine on “Biosignal Interpretation: Advanced Methods for Studying Cardiovascular and Respiratory Systems”.Background: Adaptation of the QT-interval to changes in heart rate reflects on the body-surface electrocardiogram the adaptation of action potential duration (APD) at the cellular level. The initial fast phase of APD adaptation has been shown to modulate the arrhythmia substrate. Whether the slow phase is potentially proarrhythmic remains unclear.Objectives: To analyze in-vivo human data and use computer simulations to examine effects of the slow APD adaptation phase on dispersion of repolarization and reentry in the human ventricle.Methods: Electrograms were acquired from 10 left and 10 right ventricle (LV/RV) endocardial sites in 15 patients with normal ventricles during RV pacing. Activation-recovery intervals, as a surrogate for APD, were measured during a sustained increase in heart rate. Observed dynamics were studied using computer simulations of human tissue electrophysiology.Results: Spatial heterogeneity of rate adaptation was observed in all patients. Inhomogeneity in slow APD adaptation time constants (ΔTs) was greater in LV than RV (ΔTs LV = 31.8 ± 13.2, ΔTs RV = 19.0 ± 12.8 s, P < 0.01). Simulations showed that altering local slow time constants of adaptation was sufficient to convert partial wavefront block to block with successful reentry.Conclusions: Using electrophysiological data acquired in-vivo in human and computer simulations, we identify heterogeneity in the slow phase of APD adaptation as an important component of arrhythmogenesis.
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32
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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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33
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Sirish P, Ledford HA, Timofeyev V, Thai PN, Ren L, Kim HJ, Park S, Lee JH, Dai G, Moshref M, Sihn CR, Chen WC, Timofeyeva MV, Jian Z, Shimkunas R, Izu LT, Chiamvimonvat N, Chen-Izu Y, Yamoah EN, Zhang XD. Action Potential Shortening and Impairment of Cardiac Function by Ablation of Slc26a6. Circ Arrhythm Electrophysiol 2017; 10:CIRCEP.117.005267. [PMID: 29025768 DOI: 10.1161/circep.117.005267] [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: 03/26/2017] [Accepted: 08/23/2017] [Indexed: 12/18/2022]
Abstract
BACKGROUND Intracellular pH (pHi) is critical to cardiac excitation and contraction; uncompensated changes in pHi impair cardiac function and trigger arrhythmia. Several ion transporters participate in cardiac pHi regulation. Our previous studies identified several isoforms of a solute carrier Slc26a6 to be highly expressed in cardiomyocytes. We show that Slc26a6 mediates electrogenic Cl-/HCO3- exchange activities in cardiomyocytes, suggesting the potential role of Slc26a6 in regulation of not only pHi, but also cardiac excitability. METHODS AND RESULTS To test the mechanistic role of Slc26a6 in the heart, we took advantage of Slc26a6 knockout (Slc26a6-/- ) mice using both in vivo and in vitro analyses. Consistent with our prediction of its electrogenic activities, ablation of Slc26a6 results in action potential shortening. There are reduced Ca2+ transient and sarcoplasmic reticulum Ca2+ load, together with decreased sarcomere shortening in Slc26a6-/- cardiomyocytes. These abnormalities translate into reduced fractional shortening and cardiac contractility at the in vivo level. Additionally, pHi is elevated in Slc26a6-/- cardiomyocytes with slower recovery kinetics from intracellular alkalization, consistent with the Cl-/HCO3- exchange activities of Slc26a6. Moreover, Slc26a6-/- mice show evidence of sinus bradycardia and fragmented QRS complex, supporting the critical role of Slc26a6 in cardiac conduction system. CONCLUSIONS Our study provides mechanistic insights into Slc26a6, a unique cardiac electrogenic Cl-/HCO3- transporter in ventricular myocytes, linking the critical roles of Slc26a6 in regulation of pHi, excitability, and contractility. pHi is a critical regulator of other membrane and contractile proteins. Future studies are needed to investigate possible changes in these proteins in Slc26a6-/- mice.
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Affiliation(s)
- Padmini Sirish
- From the Division of Cardiovascular Medicine, Department of Internal Medicine (P.S., H.A.L., V.T., P.N.T., L.R., S.P., G.D., M.M., C.-R.S., W.C.C., M.V.T., N.C., Y.C.-I., X.-D.Z.), Center for Neuroscience (H.J.K.), Department of Pharmacology (Z.J., R.S., L.T.I., N.C., Y.C.-I.) and Department of Biomedical Engineering (R.S., Y.C.-I.), University of California, Davis; Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno (J.H.L., E.N.Y.); and Department of Veterans Affairs, Northern California Health Care System, Mather (M.V.T., N.C., X.-D.Z.)
| | - Hannah A Ledford
- From the Division of Cardiovascular Medicine, Department of Internal Medicine (P.S., H.A.L., V.T., P.N.T., L.R., S.P., G.D., M.M., C.-R.S., W.C.C., M.V.T., N.C., Y.C.-I., X.-D.Z.), Center for Neuroscience (H.J.K.), Department of Pharmacology (Z.J., R.S., L.T.I., N.C., Y.C.-I.) and Department of Biomedical Engineering (R.S., Y.C.-I.), University of California, Davis; Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno (J.H.L., E.N.Y.); and Department of Veterans Affairs, Northern California Health Care System, Mather (M.V.T., N.C., X.-D.Z.)
| | - Valeriy Timofeyev
- From the Division of Cardiovascular Medicine, Department of Internal Medicine (P.S., H.A.L., V.T., P.N.T., L.R., S.P., G.D., M.M., C.-R.S., W.C.C., M.V.T., N.C., Y.C.-I., X.-D.Z.), Center for Neuroscience (H.J.K.), Department of Pharmacology (Z.J., R.S., L.T.I., N.C., Y.C.-I.) and Department of Biomedical Engineering (R.S., Y.C.-I.), University of California, Davis; Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno (J.H.L., E.N.Y.); and Department of Veterans Affairs, Northern California Health Care System, Mather (M.V.T., N.C., X.-D.Z.)
| | - Phung N Thai
- From the Division of Cardiovascular Medicine, Department of Internal Medicine (P.S., H.A.L., V.T., P.N.T., L.R., S.P., G.D., M.M., C.-R.S., W.C.C., M.V.T., N.C., Y.C.-I., X.-D.Z.), Center for Neuroscience (H.J.K.), Department of Pharmacology (Z.J., R.S., L.T.I., N.C., Y.C.-I.) and Department of Biomedical Engineering (R.S., Y.C.-I.), University of California, Davis; Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno (J.H.L., E.N.Y.); and Department of Veterans Affairs, Northern California Health Care System, Mather (M.V.T., N.C., X.-D.Z.)
| | - Lu Ren
- From the Division of Cardiovascular Medicine, Department of Internal Medicine (P.S., H.A.L., V.T., P.N.T., L.R., S.P., G.D., M.M., C.-R.S., W.C.C., M.V.T., N.C., Y.C.-I., X.-D.Z.), Center for Neuroscience (H.J.K.), Department of Pharmacology (Z.J., R.S., L.T.I., N.C., Y.C.-I.) and Department of Biomedical Engineering (R.S., Y.C.-I.), University of California, Davis; Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno (J.H.L., E.N.Y.); and Department of Veterans Affairs, Northern California Health Care System, Mather (M.V.T., N.C., X.-D.Z.)
| | - Hyo Jeong Kim
- From the Division of Cardiovascular Medicine, Department of Internal Medicine (P.S., H.A.L., V.T., P.N.T., L.R., S.P., G.D., M.M., C.-R.S., W.C.C., M.V.T., N.C., Y.C.-I., X.-D.Z.), Center for Neuroscience (H.J.K.), Department of Pharmacology (Z.J., R.S., L.T.I., N.C., Y.C.-I.) and Department of Biomedical Engineering (R.S., Y.C.-I.), University of California, Davis; Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno (J.H.L., E.N.Y.); and Department of Veterans Affairs, Northern California Health Care System, Mather (M.V.T., N.C., X.-D.Z.)
| | - Seojin Park
- From the Division of Cardiovascular Medicine, Department of Internal Medicine (P.S., H.A.L., V.T., P.N.T., L.R., S.P., G.D., M.M., C.-R.S., W.C.C., M.V.T., N.C., Y.C.-I., X.-D.Z.), Center for Neuroscience (H.J.K.), Department of Pharmacology (Z.J., R.S., L.T.I., N.C., Y.C.-I.) and Department of Biomedical Engineering (R.S., Y.C.-I.), University of California, Davis; Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno (J.H.L., E.N.Y.); and Department of Veterans Affairs, Northern California Health Care System, Mather (M.V.T., N.C., X.-D.Z.)
| | - Jeong Han Lee
- From the Division of Cardiovascular Medicine, Department of Internal Medicine (P.S., H.A.L., V.T., P.N.T., L.R., S.P., G.D., M.M., C.-R.S., W.C.C., M.V.T., N.C., Y.C.-I., X.-D.Z.), Center for Neuroscience (H.J.K.), Department of Pharmacology (Z.J., R.S., L.T.I., N.C., Y.C.-I.) and Department of Biomedical Engineering (R.S., Y.C.-I.), University of California, Davis; Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno (J.H.L., E.N.Y.); and Department of Veterans Affairs, Northern California Health Care System, Mather (M.V.T., N.C., X.-D.Z.)
| | - Gu Dai
- From the Division of Cardiovascular Medicine, Department of Internal Medicine (P.S., H.A.L., V.T., P.N.T., L.R., S.P., G.D., M.M., C.-R.S., W.C.C., M.V.T., N.C., Y.C.-I., X.-D.Z.), Center for Neuroscience (H.J.K.), Department of Pharmacology (Z.J., R.S., L.T.I., N.C., Y.C.-I.) and Department of Biomedical Engineering (R.S., Y.C.-I.), University of California, Davis; Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno (J.H.L., E.N.Y.); and Department of Veterans Affairs, Northern California Health Care System, Mather (M.V.T., N.C., X.-D.Z.)
| | - Maryam Moshref
- From the Division of Cardiovascular Medicine, Department of Internal Medicine (P.S., H.A.L., V.T., P.N.T., L.R., S.P., G.D., M.M., C.-R.S., W.C.C., M.V.T., N.C., Y.C.-I., X.-D.Z.), Center for Neuroscience (H.J.K.), Department of Pharmacology (Z.J., R.S., L.T.I., N.C., Y.C.-I.) and Department of Biomedical Engineering (R.S., Y.C.-I.), University of California, Davis; Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno (J.H.L., E.N.Y.); and Department of Veterans Affairs, Northern California Health Care System, Mather (M.V.T., N.C., X.-D.Z.)
| | - Choong-Ryoul Sihn
- From the Division of Cardiovascular Medicine, Department of Internal Medicine (P.S., H.A.L., V.T., P.N.T., L.R., S.P., G.D., M.M., C.-R.S., W.C.C., M.V.T., N.C., Y.C.-I., X.-D.Z.), Center for Neuroscience (H.J.K.), Department of Pharmacology (Z.J., R.S., L.T.I., N.C., Y.C.-I.) and Department of Biomedical Engineering (R.S., Y.C.-I.), University of California, Davis; Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno (J.H.L., E.N.Y.); and Department of Veterans Affairs, Northern California Health Care System, Mather (M.V.T., N.C., X.-D.Z.)
| | - Wei Chun Chen
- From the Division of Cardiovascular Medicine, Department of Internal Medicine (P.S., H.A.L., V.T., P.N.T., L.R., S.P., G.D., M.M., C.-R.S., W.C.C., M.V.T., N.C., Y.C.-I., X.-D.Z.), Center for Neuroscience (H.J.K.), Department of Pharmacology (Z.J., R.S., L.T.I., N.C., Y.C.-I.) and Department of Biomedical Engineering (R.S., Y.C.-I.), University of California, Davis; Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno (J.H.L., E.N.Y.); and Department of Veterans Affairs, Northern California Health Care System, Mather (M.V.T., N.C., X.-D.Z.)
| | - Maria Valeryevna Timofeyeva
- From the Division of Cardiovascular Medicine, Department of Internal Medicine (P.S., H.A.L., V.T., P.N.T., L.R., S.P., G.D., M.M., C.-R.S., W.C.C., M.V.T., N.C., Y.C.-I., X.-D.Z.), Center for Neuroscience (H.J.K.), Department of Pharmacology (Z.J., R.S., L.T.I., N.C., Y.C.-I.) and Department of Biomedical Engineering (R.S., Y.C.-I.), University of California, Davis; Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno (J.H.L., E.N.Y.); and Department of Veterans Affairs, Northern California Health Care System, Mather (M.V.T., N.C., X.-D.Z.)
| | - Zhong Jian
- From the Division of Cardiovascular Medicine, Department of Internal Medicine (P.S., H.A.L., V.T., P.N.T., L.R., S.P., G.D., M.M., C.-R.S., W.C.C., M.V.T., N.C., Y.C.-I., X.-D.Z.), Center for Neuroscience (H.J.K.), Department of Pharmacology (Z.J., R.S., L.T.I., N.C., Y.C.-I.) and Department of Biomedical Engineering (R.S., Y.C.-I.), University of California, Davis; Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno (J.H.L., E.N.Y.); and Department of Veterans Affairs, Northern California Health Care System, Mather (M.V.T., N.C., X.-D.Z.)
| | - Rafael Shimkunas
- From the Division of Cardiovascular Medicine, Department of Internal Medicine (P.S., H.A.L., V.T., P.N.T., L.R., S.P., G.D., M.M., C.-R.S., W.C.C., M.V.T., N.C., Y.C.-I., X.-D.Z.), Center for Neuroscience (H.J.K.), Department of Pharmacology (Z.J., R.S., L.T.I., N.C., Y.C.-I.) and Department of Biomedical Engineering (R.S., Y.C.-I.), University of California, Davis; Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno (J.H.L., E.N.Y.); and Department of Veterans Affairs, Northern California Health Care System, Mather (M.V.T., N.C., X.-D.Z.)
| | - Leighton T Izu
- From the Division of Cardiovascular Medicine, Department of Internal Medicine (P.S., H.A.L., V.T., P.N.T., L.R., S.P., G.D., M.M., C.-R.S., W.C.C., M.V.T., N.C., Y.C.-I., X.-D.Z.), Center for Neuroscience (H.J.K.), Department of Pharmacology (Z.J., R.S., L.T.I., N.C., Y.C.-I.) and Department of Biomedical Engineering (R.S., Y.C.-I.), University of California, Davis; Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno (J.H.L., E.N.Y.); and Department of Veterans Affairs, Northern California Health Care System, Mather (M.V.T., N.C., X.-D.Z.)
| | - Nipavan Chiamvimonvat
- From the Division of Cardiovascular Medicine, Department of Internal Medicine (P.S., H.A.L., V.T., P.N.T., L.R., S.P., G.D., M.M., C.-R.S., W.C.C., M.V.T., N.C., Y.C.-I., X.-D.Z.), Center for Neuroscience (H.J.K.), Department of Pharmacology (Z.J., R.S., L.T.I., N.C., Y.C.-I.) and Department of Biomedical Engineering (R.S., Y.C.-I.), University of California, Davis; Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno (J.H.L., E.N.Y.); and Department of Veterans Affairs, Northern California Health Care System, Mather (M.V.T., N.C., X.-D.Z.)
| | - Ye Chen-Izu
- From the Division of Cardiovascular Medicine, Department of Internal Medicine (P.S., H.A.L., V.T., P.N.T., L.R., S.P., G.D., M.M., C.-R.S., W.C.C., M.V.T., N.C., Y.C.-I., X.-D.Z.), Center for Neuroscience (H.J.K.), Department of Pharmacology (Z.J., R.S., L.T.I., N.C., Y.C.-I.) and Department of Biomedical Engineering (R.S., Y.C.-I.), University of California, Davis; Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno (J.H.L., E.N.Y.); and Department of Veterans Affairs, Northern California Health Care System, Mather (M.V.T., N.C., X.-D.Z.)
| | - Ebenezer N Yamoah
- From the Division of Cardiovascular Medicine, Department of Internal Medicine (P.S., H.A.L., V.T., P.N.T., L.R., S.P., G.D., M.M., C.-R.S., W.C.C., M.V.T., N.C., Y.C.-I., X.-D.Z.), Center for Neuroscience (H.J.K.), Department of Pharmacology (Z.J., R.S., L.T.I., N.C., Y.C.-I.) and Department of Biomedical Engineering (R.S., Y.C.-I.), University of California, Davis; Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno (J.H.L., E.N.Y.); and Department of Veterans Affairs, Northern California Health Care System, Mather (M.V.T., N.C., X.-D.Z.)
| | - Xiao-Dong Zhang
- From the Division of Cardiovascular Medicine, Department of Internal Medicine (P.S., H.A.L., V.T., P.N.T., L.R., S.P., G.D., M.M., C.-R.S., W.C.C., M.V.T., N.C., Y.C.-I., X.-D.Z.), Center for Neuroscience (H.J.K.), Department of Pharmacology (Z.J., R.S., L.T.I., N.C., Y.C.-I.) and Department of Biomedical Engineering (R.S., Y.C.-I.), University of California, Davis; Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno (J.H.L., E.N.Y.); and Department of Veterans Affairs, Northern California Health Care System, Mather (M.V.T., N.C., X.-D.Z.).
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Krogh-Madsen T, Christini DJ. Slow [Na +] i dynamics impacts arrhythmogenesis and spiral wave reentry in cardiac myocyte ionic model. CHAOS (WOODBURY, N.Y.) 2017; 27:093907. [PMID: 28964146 DOI: 10.1063/1.4999475] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Accumulation of intracellular Na+ is gaining recognition as an important regulator of cardiac myocyte electrophysiology. The intracellular Na+ concentration can be an important determinant of the cardiac action potential duration, can modulate the tissue-level conduction of excitation waves, and can alter vulnerability to arrhythmias. Mathematical models of cardiac electrophysiology often incorporate a dynamic intracellular Na+ concentration, which changes much more slowly than the remaining variables. We investigated the dependence of several arrhythmogenesis-related factors on [Na+]i in a mathematical model of the human atrial action potential. In cell simulations, we found that [Na+]i accumulation stabilizes the action potential duration to variations in several conductances and that the slow dynamics of [Na+]i impacts bifurcations to pro-arrhythmic afterdepolarizations, causing intermittency between different rhythms. In long-lasting tissue simulations of spiral wave reentry, [Na+]i becomes spatially heterogeneous with a decreased area around the spiral wave rotation center. This heterogeneous region forms a functional anchor, resulting in diminished meandering of the spiral wave. Our findings suggest that slow, physiological, rate-dependent variations in [Na+]i may play complex roles in cellular and tissue-level cardiac dynamics.
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Affiliation(s)
- Trine Krogh-Madsen
- Greenberg Division of Cardiology, Weill Cornell Medicine, New York, New York 10065, USA; Institute for Computational Biomedicine, Weill Cornell Medicine, New York, New York 10065, USA; and Cardiovascular Research Institute, Weill Cornell Medicine, New York, New York 10065, USA
| | - David J Christini
- Greenberg Division of Cardiology, Weill Cornell Medicine, New York, New York 10065, USA; Institute for Computational Biomedicine, Weill Cornell Medicine, New York, New York 10065, USA; and Cardiovascular Research Institute, Weill Cornell Medicine, New York, New York 10065, USA
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Wallman M, Sandberg F. Characterisation of human AV-nodal properties using a network model. Med Biol Eng Comput 2017; 56:247-259. [DOI: 10.1007/s11517-017-1684-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Accepted: 07/03/2017] [Indexed: 02/05/2023]
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Sánchez C, Bueno-Orovio A, Pueyo E, Rodríguez B. Atrial Fibrillation Dynamics and Ionic Block Effects in Six Heterogeneous Human 3D Virtual Atria with Distinct Repolarization Dynamics. Front Bioeng Biotechnol 2017; 5:29. [PMID: 28534025 PMCID: PMC5420585 DOI: 10.3389/fbioe.2017.00029] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 04/18/2017] [Indexed: 12/19/2022] Open
Abstract
Atrial fibrillation (AF) usually manifests as reentrant circuits propagating through the whole atria creating chaotic activation patterns. Little is yet known about how differences in electrophysiological and ionic properties between patients modulate reentrant patterns in AF. The goal of this study is to quantify how variability in action potential duration (APD) at different stages of repolarization determines AF dynamics and their modulation by ionic block using a set of virtual whole-atria human models. Six human whole-atria models are constructed based on the same anatomical structure and fiber orientation, but with different electrophysiological phenotypes. Membrane kinetics for each whole-atria model are selected with distinct APD characteristics at 20, 50, and 90% repolarization, from an experimentally calibrated population of human atrial action potential models, including AF remodeling and acetylcholine parasympathetic effects. Our simulations show that in all whole-atria models, reentrant circuits tend to organize around the pulmonary veins and the right atrial appendage, thus leading to higher dominant frequency (DF) and more organized activation in the left atrium than in the right atrium. Differences in APD in all phases of repolarization (not only APD90) yielded quantitative differences in fibrillation patterns with long APD associated with slower and more regular dynamics. Long APD50 and APD20 were associated with increased interatrial conduction block and interatrial differences in DF and organization index, creating reentry instability and self-termination in some cases. Specific inhibitions of IK1, INaK, or INa reduce DF and organization of the arrhythmia by enlarging wave meandering, reducing the number of secondary wavelets, and promoting interatrial block in all six virtual patients, especially for the phenotypes with short APD at 20, 50, and/or 90% repolarization. This suggests that therapies aiming at prolonging the early phase of repolarization might constitute effective antiarrhythmic strategies for the pharmacological management of AF. In summary, simulations report significant differences in atrial fibrillatory dynamics resulting from differences in APD at all phases of repolarization.
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Affiliation(s)
- Carlos Sánchez
- Biosignal Interpretation and Computational Simulation (BSICoS), I3A and IIS, University of Zaragoza, Zaragoza, Spain.,Defense University Centre (CUD), General Military Academy of Zaragoza (AGM), Zaragoza, Spain
| | | | - Esther Pueyo
- Biosignal Interpretation and Computational Simulation (BSICoS), I3A and IIS, University of Zaragoza, Zaragoza, Spain.,Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Zaragoza, Spain
| | - Blanca Rodríguez
- Department of Computer Science, University of Oxford, Oxford, UK
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Britton OJ, Bueno-Orovio A, Virág L, Varró A, Rodriguez B. The Electrogenic Na +/K + Pump Is a Key Determinant of Repolarization Abnormality Susceptibility in Human Ventricular Cardiomyocytes: A Population-Based Simulation Study. Front Physiol 2017; 8:278. [PMID: 28529489 PMCID: PMC5418229 DOI: 10.3389/fphys.2017.00278] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Accepted: 04/18/2017] [Indexed: 11/23/2022] Open
Abstract
Background: Cellular repolarization abnormalities occur unpredictably due to disease and drug effects, and can occur even in cardiomyocytes that exhibit normal action potentials (AP) under control conditions. Variability in ion channel densities may explain differences in this susceptibility to repolarization abnormalities. Here, we quantify the importance of key ionic mechanisms determining repolarization abnormalities following ionic block in human cardiomyocytes yielding normal APs under control conditions. Methods and Results: Sixty two AP recordings from non-diseased human heart preparations were used to construct a population of human ventricular models with normal APs and a wide range of ion channel densities. Multichannel ionic block was applied to investigate susceptibility to repolarization abnormalities. IKr block was necessary for the development of repolarization abnormalities. Models that developed repolarization abnormalities over the widest range of blocks possessed low Na+/K+ pump conductance below 50% of baseline, and ICaL conductance above 70% of baseline. Furthermore, INaK made the second largest contribution to repolarizing current in control simulations and the largest contribution under 75% IKr block. Reversing intracellular Na+ overload caused by reduced INaK was not sufficient to prevent abnormalities in models with low Na+/K+ pump conductance, while returning Na+/K+ pump conductance to normal substantially reduced abnormality occurrence, indicating INaK is an important repolarization current. Conclusions: INaK is an important determinant of repolarization abnormality susceptibility in human ventricular cardiomyocytes, through its contribution to repolarization current rather than homeostasis. While we found IKr block to be necessary for repolarization abnormalities to occur, INaK decrease, as in disease, may amplify the pro-arrhythmic risk of drug-induced IKr block in humans.
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Affiliation(s)
| | | | - László Virág
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of SzegedSzeged, Hungary
| | - András Varró
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of SzegedSzeged, Hungary
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Tejral G, Sopko B, Necas A, Schoner W, Amler E. Computer modelling reveals new conformers of the ATP binding loop of Na +/K +-ATPase involved in the transphosphorylation process of the sodium pump. PeerJ 2017; 5:e3087. [PMID: 28316890 PMCID: PMC5354106 DOI: 10.7717/peerj.3087] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 02/14/2017] [Indexed: 01/02/2023] Open
Abstract
Hydrolysis of ATP by Na+/K+-ATPase, a P-Type ATPase, catalyzing active Na+ and K+ transport through cellular membranes leads transiently to a phosphorylation of its catalytical α-subunit. Surprisingly, three-dimensional molecular structure analysis of P-type ATPases reveals that binding of ATP to the N-domain connected by a hinge to the P-domain is much too far away from the Asp369 to allow the transfer of ATP’s terminal phosphate to its aspartyl-phosphorylation site. In order to get information for how the transfer of the γ-phosphate group of ATP to the Asp369 is achieved, analogous molecular modeling of the M4–M5 loop of ATPase was performed using the crystal data of Na+/K+-ATPase of different species. Analogous molecular modeling of the cytoplasmic loop between Thr338 and Ile760 of the α2-subunit of Na+/K+-ATPase and the analysis of distances between the ATP binding site and phosphorylation site revealed the existence of two ATP binding sites in the open conformation; the first one close to Phe475 in the N-domain, the other one close to Asp369 in the P-domain. However, binding of Mg2+•ATP to any of these sites in the “open conformation” may not lead to phosphorylation of Asp369. Additional conformations of the cytoplasmic loop were found wobbling between “open conformation” <==> “semi-open conformation <==> “closed conformation” in the absence of 2Mg2+•ATP. The cytoplasmic loop’s conformational change to the “semi-open conformation”—characterized by a hydrogen bond between Arg543 and Asp611—triggers by binding of 2Mg2+•ATP to a single ATP site and conversion to the “closed conformation” the phosphorylation of Asp369 in the P-domain, and hence the start of Na+/K+-activated ATP hydrolysis.
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Affiliation(s)
- Gracian Tejral
- Department of Biophysics, 2nd Faculty of Medicine, Charles University Prague, Prague, Czech Republic; Laboratory of Tissue Engineering, Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Bruno Sopko
- Department of Medical Chemistry and Clinical Biochemistry, 2nd Faculty of Medicine, Charles University Prague , Prague , Czech Republic
| | - Alois Necas
- Small Animal Clinic, Faculty of Veterinary Medicine, University of Veterinary and Pharmaceutical Science , Brno , Czech Republic
| | - Wilhelm Schoner
- Institute of Biochemistry and Endocrinology, University of Giessen , Giessen , Germany
| | - Evzen Amler
- Department of Biophysics, 2nd Faculty of Medicine, Charles University Prague, Prague, Czech Republic; Laboratory of Tissue Engineering, Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Prague, Czech Republic
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Tao J, Li Y, Vig DK, Sun SX. Cell mechanics: a dialogue. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2017; 80:036601. [PMID: 28129208 PMCID: PMC5518794 DOI: 10.1088/1361-6633/aa5282] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Under the microscope, eukaryotic animal cells can adopt a variety of different shapes and sizes. These cells also move and deform, and the physical mechanisms driving these movements and shape changes are important in fundamental cell biology, tissue mechanics, as well as disease biology. This article reviews some of the basic mechanical concepts in cells, emphasizing continuum mechanics description of cytoskeletal networks and hydrodynamic flows across the cell membrane. We discuss how cells can generate movement and shape changes by controlling mass fluxes at the cell boundary. These mass fluxes can come from polymerization/depolymerization of actin cytoskeleton, as well as osmotic and hydraulic pressure-driven flow of water across the cell membrane. By combining hydraulic pressure control with force balance conditions at the cell surface, we discuss a quantitative mechanism of cell shape and volume control. The broad consequences of this model on cell mechanosensation and tissue mechanics are outlined.
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Affiliation(s)
- Jiaxiang Tao
- Departments of Mechanical Engineering, Johns Hopkins University, Baltimore MD, United States of America
- Physical Sciences in Oncology Center, Johns Hopkins University, Baltimore MD, United States of America
| | - Yizeng Li
- Departments of Mechanical Engineering, Johns Hopkins University, Baltimore MD, United States of America
- Institute of NanoBioTechnology, Johns Hopkins University, Baltimore MD, United States of America
| | - Dhruv K Vig
- Departments of Mechanical Engineering, Johns Hopkins University, Baltimore MD, United States of America
- Institute of NanoBioTechnology, Johns Hopkins University, Baltimore MD, United States of America
| | - Sean X Sun
- Departments of Mechanical Engineering, Johns Hopkins University, Baltimore MD, United States of America
- Biomedical Engineering, Johns Hopkins University, Baltimore MD, United States of America
- Physical Sciences in Oncology Center, Johns Hopkins University, Baltimore MD, United States of America
- Institute of NanoBioTechnology, Johns Hopkins University, Baltimore MD, United States of America
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Chiamvimonvat N, Chen-Izu Y, Clancy CE, Deschenes I, Dobrev D, Heijman J, Izu L, Qu Z, Ripplinger CM, Vandenberg JI, Weiss JN, Koren G, Banyasz T, Grandi E, Sanguinetti MC, Bers DM, Nerbonne JM. Potassium currents in the heart: functional roles in repolarization, arrhythmia and therapeutics. J Physiol 2017; 595:2229-2252. [PMID: 27808412 DOI: 10.1113/jp272883] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 10/11/2016] [Indexed: 12/19/2022] Open
Abstract
This is the second of the two White Papers from the fourth UC Davis Cardiovascular Symposium Systems Approach to Understanding Cardiac Excitation-Contraction Coupling and Arrhythmias (3-4 March 2016), a biennial event that brings together leading experts in different fields of cardiovascular research. The theme of the 2016 symposium was 'K+ channels and regulation', and the objectives of the conference were severalfold: (1) to identify current knowledge gaps; (2) to understand what may go wrong in the diseased heart and why; (3) to identify possible novel therapeutic targets; and (4) to further the development of systems biology approaches to decipher the molecular mechanisms and treatment of cardiac arrhythmias. The sessions of the Symposium focusing on the functional roles of the cardiac K+ channel in health and disease, as well as K+ channels as therapeutic targets, were contributed by Ye Chen-Izu, Gideon Koren, James Weiss, David Paterson, David Christini, Dobromir Dobrev, Jordi Heijman, Thomas O'Hara, Crystal Ripplinger, Zhilin Qu, Jamie Vandenberg, Colleen Clancy, Isabelle Deschenes, Leighton Izu, Tamas Banyasz, Andras Varro, Heike Wulff, Eleonora Grandi, Michael Sanguinetti, Donald Bers, Jeanne Nerbonne and Nipavan Chiamvimonvat as speakers and panel discussants. This article summarizes state-of-the-art knowledge and controversies on the functional roles of cardiac K+ channels in normal and diseased heart. We endeavour to integrate current knowledge at multiple scales, from the single cell to the whole organ levels, and from both experimental and computational studies.
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Affiliation(s)
- Nipavan Chiamvimonvat
- Department of Internal Medicine, University of California, Davis, Genome and Biomedical Science Facility, Rm 6315, Davis, CA, 95616, USA.,Department of Veterans Affairs, Northern California Health Care System, Mather, CA, 95655, USA
| | - Ye Chen-Izu
- Department of Internal Medicine, University of California, Davis, Genome and Biomedical Science Facility, Rm 6315, Davis, CA, 95616, USA.,Department of Pharmacology, University of California, Davis, Genome and Biomedical Science Facility, Rm 3503, Davis, CA, 95616, USA.,Department of Biomedical Engineering, University of California, Davis, Genome and Biomedical Science Facility, Rm 2303, Davis, CA, 95616, USA
| | - Colleen E Clancy
- Department of Pharmacology, University of California, Davis, Genome and Biomedical Science Facility, Rm 3503, Davis, CA, 95616, USA
| | - Isabelle Deschenes
- Department of Physiology and Biophysics, and Biomedical Engineering, Case Western Reserve University, Cleveland, OH, 44109, USA.,Heart and Vascular Research Center, MetroHealth Medical Center, Cleveland, OH, 44109, USA
| | - Dobromir Dobrev
- Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Hufelandstrasse 55, 45122, Essen, Germany
| | - Jordi Heijman
- Department of Cardiology, Cardiovascular Research Institute Maastricht, Faculty of Health, Medicine, and Life Sciences, Maastricht University, Maastricht, The Netherlands
| | - Leighton Izu
- Department of Pharmacology, University of California, Davis, Genome and Biomedical Science Facility, Rm 3503, Davis, CA, 95616, USA
| | - Zhilin Qu
- Division of Cardiology, Cardiovascular Research Laboratory, David Geffen School of Medicine at UCLA, 3645 MRL, Los Angeles, CA, 90095, USA
| | - Crystal M Ripplinger
- Department of Pharmacology, University of California, Davis, Genome and Biomedical Science Facility, Rm 3503, Davis, CA, 95616, USA
| | - Jamie I Vandenberg
- Victor Chang Cardiac Research Institute, 405 Liverpool Street, Darlinghurst, NSW, 2010, Australia
| | - James N Weiss
- Division of Cardiology, Cardiovascular Research Laboratory, David Geffen School of Medicine at UCLA, 3645 MRL, Los Angeles, CA, 90095, USA
| | - Gideon Koren
- Cardiovascular Research Center, Rhode Island Hospital and the Cardiovascular Institute, The Warren Alpert Medical School of Brown University, Providence, RI, 02903, USA
| | - Tamas Banyasz
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Eleonora Grandi
- Department of Pharmacology, University of California, Davis, Genome and Biomedical Science Facility, Rm 3503, Davis, CA, 95616, USA
| | - Michael C Sanguinetti
- Department of Internal Medicine, University of Utah, Nora Eccles Harrison Cardiovascular Research & Training Institute, Salt Lake City, UT, 84112, USA
| | - Donald M Bers
- Department of Pharmacology, University of California, Davis, Genome and Biomedical Science Facility, Rm 3503, Davis, CA, 95616, USA
| | - Jeanne M Nerbonne
- Departments of Developmental Biology and Internal Medicine, Cardiovascular Division, Washington University Medical School, St Louis, MO, 63110, USA
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Liberos A, Bueno-Orovio A, Rodrigo M, Ravens U, Hernandez-Romero I, Fernandez-Aviles F, Guillem MS, Rodriguez B, Climent AM. Balance between sodium and calcium currents underlying chronic atrial fibrillation termination: An in silico intersubject variability study. Heart Rhythm 2016; 13:2358-2365. [PMID: 27569443 PMCID: PMC5221730 DOI: 10.1016/j.hrthm.2016.08.028] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Indexed: 11/29/2022]
Abstract
BACKGROUND Atrial remodeling as a result of long-standing persistent atrial fibrillation (AF) induces substrate modifications that lead to different perpetuation mechanisms than in paroxysmal AF and a reduction in the efficacy of antiarrhythmic treatments. OBJECTIVE The purpose of this study was to identify the ionic current modifications that could destabilize reentries during chronic AF and serve to personalize antiarrhythmic strategies. METHODS A population of 173 mathematical models of remodeled human atrial tissue with realistic intersubject variability was developed based on action potential recordings of 149 patients diagnosed with AF. The relationship of each ionic current with AF maintenance and the dynamics of functional reentries (rotor meandering, dominant frequency) were evaluated by means of 3-dimensional simulations. RESULTS Self-sustained reentries were maintained in 126 (73%) of the simulations. AF perpetuation was associated with higher expressions of INa and ICaL (P <.01), with no significant differences in the remaining currents. ICaL blockade promoted AF extinction in 30% of these 126 models. The mechanism of AF termination was related with collisions between rotors because of an increase in rotor meandering (1.71 ± 2.01cm2) and presented an increased efficacy in models with a depressed INa (P <.01). CONCLUSION Mathematical simulations based on a population of models representing intersubject variability allow the identification of ionic mechanisms underlying rotor dynamics and the definition of new personalized pharmacologic strategies. Our results suggest that the underlying mechanism of the diverging success of ICaL block as an antiarrhythmic strategy is dependent on the basal availability of sodium and calcium ion channel conductivities.
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Affiliation(s)
- Alejandro Liberos
- ITACA, Universitat Politècnica de València, València, Spain; Cardiology Department, Hospital General Universitario Gregorio Marañón, Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain.
| | | | - Miguel Rodrigo
- ITACA, Universitat Politècnica de València, València, Spain
| | - Ursula Ravens
- Department of Pharmacology and Toxicology, Technical University Dresden, Dresden, Germany
| | - Ismael Hernandez-Romero
- Cardiology Department, Hospital General Universitario Gregorio Marañón, Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain; Department of Signal Theory and Communications, Rey Juan Carlos University, Fuenlabrada, Madrid, Spain
| | - Francisco Fernandez-Aviles
- Cardiology Department, Hospital General Universitario Gregorio Marañón, Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain
| | | | - Blanca Rodriguez
- Department of Computer Science, University of Oxford, Oxford, United Kingdom
| | - Andreu M Climent
- Cardiology Department, Hospital General Universitario Gregorio Marañón, Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain
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Plumlee M, Joseph VR, Yang H. Calibrating Functional Parameters in the Ion Channel Models of Cardiac Cells. J Am Stat Assoc 2016. [DOI: 10.1080/01621459.2015.1119695] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Passini E, Mincholé A, Coppini R, Cerbai E, Rodriguez B, Severi S, Bueno-Orovio A. Mechanisms of pro-arrhythmic abnormalities in ventricular repolarisation and anti-arrhythmic therapies in human hypertrophic cardiomyopathy. J Mol Cell Cardiol 2016; 96:72-81. [PMID: 26385634 PMCID: PMC4915817 DOI: 10.1016/j.yjmcc.2015.09.003] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2015] [Revised: 08/05/2015] [Accepted: 09/11/2015] [Indexed: 12/11/2022]
Abstract
INTRODUCTION Hypertrophic cardiomyopathy (HCM) is a cause of sudden arrhythmic death, but the understanding of its pro-arrhythmic mechanisms and an effective pharmacological treatment are lacking. HCM electrophysiological remodelling includes both increased inward and reduced outward currents, but their role in promoting repolarisation abnormalities remains unknown. The goal of this study is to identify key ionic mechanisms driving repolarisation abnormalities in human HCM, and to evaluate anti-arrhythmic effects of single and multichannel inward current blocks. METHODS Experimental ionic current, action potential (AP) and Ca(2+)-transient (CaT) recordings were used to construct populations of human non-diseased and HCM AP models (n=9118), accounting for inter-subject variability. Simulations were conducted for several degrees of selective and combined inward current block. RESULTS Simulated HCM cardiomyocytes exhibited prolonged AP and CaT, diastolic Ca(2+) overload and decreased CaT amplitude, in agreement with experiments. Repolarisation abnormalities in HCM models were consistently driven by L-type Ca(2+) current (ICaL) re-activation, and ICaL block was the most effective intervention to normalise repolarisation and diastolic Ca(2+), but compromised CaT amplitude. Late Na(+) current (INaL) block partially abolished repolarisation abnormalities, with small impact on CaT. Na(+)/Ca(2+) exchanger (INCX) block effectively restored repolarisation and CaT amplitude, but increased Ca(2+) overload. Multichannel block increased efficacy in normalising repolarisation, AP biomarkers and CaT amplitude compared to selective block. CONCLUSIONS Experimentally-calibrated populations of human AP models identify ICaL re-activation as the key mechanism for repolarisation abnormalities in HCM, and combined INCX, INaL and ICaL block as effective anti-arrhythmic therapies also able to partially reverse the HCM electrophysiological phenotype.
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Affiliation(s)
- Elisa Passini
- Department of Computer Science, University of Oxford, Oxford OX13QD, United Kingdom; Department of Electrical, Electronic and Information Engineering, University of Bologna, Cesena 47521, Italy
| | - Ana Mincholé
- Department of Computer Science, University of Oxford, Oxford OX13QD, United Kingdom
| | - Raffaele Coppini
- Department NEUROFARBA, University of Florence, Florence 50139, Italy
| | - Elisabetta Cerbai
- Department NEUROFARBA, University of Florence, Florence 50139, Italy
| | - Blanca Rodriguez
- Department of Computer Science, University of Oxford, Oxford OX13QD, United Kingdom
| | - Stefano Severi
- Department of Electrical, Electronic and Information Engineering, University of Bologna, Cesena 47521, Italy
| | - Alfonso Bueno-Orovio
- Department of Computer Science, University of Oxford, Oxford OX13QD, United Kingdom.
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Multi-scale Modeling of the Cardiovascular System: Disease Development, Progression, and Clinical Intervention. Ann Biomed Eng 2016; 44:2642-60. [PMID: 27138523 DOI: 10.1007/s10439-016-1628-0] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 04/22/2016] [Indexed: 12/19/2022]
Abstract
Cardiovascular diseases (CVDs) are the leading cause of death in the western world. With the current development of clinical diagnostics to more accurately measure the extent and specifics of CVDs, a laudable goal is a better understanding of the structure-function relation in the cardiovascular system. Much of this fundamental understanding comes from the development and study of models that integrate biology, medicine, imaging, and biomechanics. Information from these models provides guidance for developing diagnostics, and implementation of these diagnostics to the clinical setting, in turn, provides data for refining the models. In this review, we introduce multi-scale and multi-physical models for understanding disease development, progression, and designing clinical interventions. We begin with multi-scale models of cardiac electrophysiology and mechanics for diagnosis, clinical decision support, personalized and precision medicine in cardiology with examples in arrhythmia and heart failure. We then introduce computational models of vasculature mechanics and associated mechanical forces for understanding vascular disease progression, designing clinical interventions, and elucidating mechanisms that underlie diverse vascular conditions. We conclude with a discussion of barriers that must be overcome to provide enhanced insights, predictions, and decisions in pre-clinical and clinical applications.
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Li Y, Mori Y, Sun SX. Flow-Driven Cell Migration under External Electric Fields. PHYSICAL REVIEW LETTERS 2015; 115:268101. [PMID: 26765031 PMCID: PMC4918809 DOI: 10.1103/physrevlett.115.268101] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Indexed: 05/30/2023]
Abstract
Electric fields influence many aspects of cell physiology, including various forms of cell migration. Many cells are sensitive to electric fields, and they can migrate toward a cathode or an anode, depending on the cell type. In this Letter, we examine an actomyosin-independent mode of cell migration under electrical fields. Our theory considers a one-dimensional cell with water and ionic fluxes at the cell boundary. Water fluxes through the membrane are governed by the osmotic pressure difference across the cell membrane. Fluxes of cations and anions across the cell membrane are determined by the properties of the ion channels as well as the external electric field. Results show that without actin polymerization and myosin contraction, electric fields can also drive cell migration, even when the cell is not polarized. The direction of migration with respect to the electric field direction is influenced by the properties of ion channels, and are cell-type dependent.
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Affiliation(s)
- Yizeng Li
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - Yoichiro Mori
- School of Mathematics, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Sean X. Sun
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA
- Johns Hopkins Physical Sciences-Oncology Center, Johns Hopkins University, Baltimore, Maryland 21218, USA
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Groenendaal W, Ortega FA, Kherlopian AR, Zygmunt AC, Krogh-Madsen T, Christini DJ. Cell-specific cardiac electrophysiology models. PLoS Comput Biol 2015; 11:e1004242. [PMID: 25928268 PMCID: PMC4415772 DOI: 10.1371/journal.pcbi.1004242] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Accepted: 03/16/2015] [Indexed: 01/25/2023] Open
Abstract
The traditional cardiac model-building paradigm involves constructing a composite model using data collected from many cells. Equations are derived for each relevant cellular component (e.g., ion channel, exchanger) independently. After the equations for all components are combined to form the composite model, a subset of parameters is tuned, often arbitrarily and by hand, until the model output matches a target objective, such as an action potential. Unfortunately, such models often fail to accurately simulate behavior that is dynamically dissimilar (e.g., arrhythmia) to the simple target objective to which the model was fit. In this study, we develop a new approach in which data are collected via a series of complex electrophysiology protocols from single cardiac myocytes and then used to tune model parameters via a parallel fitting method known as a genetic algorithm (GA). The dynamical complexity of the electrophysiological data, which can only be fit by an automated method such as a GA, leads to more accurately parameterized models that can simulate rich cardiac dynamics. The feasibility of the method is first validated computationally, after which it is used to develop models of isolated guinea pig ventricular myocytes that simulate the electrophysiological dynamics significantly better than does a standard guinea pig model. In addition to improving model fidelity generally, this approach can be used to generate a cell-specific model. By so doing, the approach may be useful in applications ranging from studying the implications of cell-to-cell variability to the prediction of intersubject differences in response to pharmacological treatment. Mathematical models of cardiac cell electrophysiology are widely used as predictive and illuminatory tools, but have been developed for decades using a suboptimal process. The models are typically constructed by manual adjustment of parameters to fit simple data and therefore often underperform when used to predict complex behavior such as arrhythmias. We present a novel method of model parameterization using automated optimization and dynamically rich fitting data and then demonstrate that this approach is better at finding the “real” model of a cell. Application of the method to cardiac myocytes leads to cell-specific models, which may enable well-controlled studies of both cellular- and subject-level population heterogeneity in disease propensity and response to therapies.
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Affiliation(s)
- Willemijn Groenendaal
- Greenberg Division of Cardiology, Weill Cornell Medical College, New York, New York, United States of America
| | - Francis A. Ortega
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, New York, United States of America
| | - Armen R. Kherlopian
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, New York, United States of America
| | | | - Trine Krogh-Madsen
- Greenberg Division of Cardiology, Weill Cornell Medical College, New York, New York, United States of America
- Institute for Computational Biomedicine, Weill Cornell Medical College, New York, New York, United States of America
| | - David J. Christini
- Greenberg Division of Cardiology, Weill Cornell Medical College, New York, New York, United States of America
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, New York, United States of America
- Institute for Computational Biomedicine, Weill Cornell Medical College, New York, New York, United States of America
- * E-mail:
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Adeniran I, MacIver DH, Hancox JC, Zhang H. Abnormal calcium homeostasis in heart failure with preserved ejection fraction is related to both reduced contractile function and incomplete relaxation: an electromechanically detailed biophysical modeling study. Front Physiol 2015; 6:78. [PMID: 25852567 PMCID: PMC4367530 DOI: 10.3389/fphys.2015.00078] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Accepted: 02/26/2015] [Indexed: 01/08/2023] Open
Abstract
Heart failure with preserved ejection fraction (HFpEF) accounts for about 50% of heart failure cases. It has features of incomplete relaxation and increased stiffness of the left ventricle. Studies from clinical electrophysiology and animal experiments have found that HFpEF is associated with impaired calcium homeostasis, ion channel remodeling and concentric left ventricle hypertrophy (LVH). However, it is still unclear how the abnormal calcium homeostasis, ion channel and structural remodeling affect the electro-mechanical dynamics of the ventricles. In this study we have developed multiscale models of the human left ventricle from single cells to the 3D organ, which take into consideration HFpEF-induced changes in calcium handling, ion channel remodeling and concentric LVH. Our simulation results suggest that at the cellular level, HFpEF reduces the systolic calcium level resulting in a reduced systolic contractile force, but elevates the diastolic calcium level resulting in an abnormal residual diastolic force. In our simulations, these abnormal electro-mechanical features of the ventricular cells became more pronounced with the increase of the heart rate. However, at the 3D organ level, the ejection fraction of the left ventricle was maintained due to the concentric LVH. The simulation results of this study mirror clinically observed features of HFpEF and provide new insights toward the understanding of the cellular bases of impaired cardiac electromechanical functions in heart failure.
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Affiliation(s)
- Ismail Adeniran
- Biological Physics Group, School of Physics and Astronomy, The University of Manchester Manchester, UK
| | - David H MacIver
- Biological Physics Group, School of Physics and Astronomy, The University of Manchester Manchester, UK ; Department of Cardiology, Taunton and Somerset Hospital Musgrove Park, Taunton, UK
| | - Jules C Hancox
- Biological Physics Group, School of Physics and Astronomy, The University of Manchester Manchester, UK ; School of Physiology and Pharmacology and Cardiovascular Research Laboratories, School of Medical Sciences Bristol, UK
| | - Henggui Zhang
- Biological Physics Group, School of Physics and Astronomy, The University of Manchester Manchester, UK ; School of Computer Science and Technology, Harbin Institute of Technology Harbin, China
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Singh H, Kaur P, Kaur P, Muthuraman A, Singh G, Kaur M. Investigation of therapeutic potential and molecular mechanism of vitamin P and digoxin in I/R-induced myocardial infarction in rat. Naunyn Schmiedebergs Arch Pharmacol 2015; 388:565-74. [PMID: 25693978 DOI: 10.1007/s00210-015-1103-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Accepted: 02/06/2015] [Indexed: 12/22/2022]
Abstract
Ischemic-reperfusion (I/R) is a major event in the pathogenesis of ischemic heart disease that leads to higher rate of mortality. The study has been designed to investigate the therapeutic potential and molecular mechanism of vitamin P and digoxin in I/R-induced myocardial infarction in isolated rat heart preparation by using Langendorff apparatus. The animals were treated with vitamin P (50 and 100 mg/kg; p.o.) and digoxin (500 μg/kg) for 5 consecutive days. Digoxin served as a positive control in the present study. On the sixth day, the heart was harvested and induced to 30 min of global ischemia followed by 120 min of reperfusion using Langendorff apparatus. The coronary effluent was collected at different time intervals (i.e. basal, 1, 15, 30, 45, 60 and 120 min.) for the assessment of myocardial contractility function. In addition, creatine kinase-M and B subunits (CK-MB), lactate dehydrogenase (LDH1) and Na(+)-K(+)-ATPase activity along with oxidative tissue biomarkers (i.e. thio-barbituric acid reactive substances (TBARS) and reduced glutathione (GSH)) changes were estimated. The I/R of myocardium produced decrease in coronary flow rate; increase in CK-MB, LDH1 and Na(+)-K(+)-ATPase activity along with increase in TBARS and decrease in GSH levels as compared to normal group. The treatment with vitamin P (100 mg/kg) and digoxin (500 μg/kg) have produced a significant (p < 0.05) ameliorative effect against I/R induced above functional, metabolic and tissue biomarkers changes. Vitamin P has an ameliorative potential against I/R induced myocardial functional changes. It may be due to its free radical scavenging and anti-infarct property via inhibition of Na(+)-K(+)-ATPase activity. Therefore, it can be used as a potential therapeutic medicine for the management of cardiovascular disorders.
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Affiliation(s)
- Harwinder Singh
- Department of Pharmacology, Cardiovascular Division, Akal Toxicology Research Centre, Akal College of Pharmacy and Technical Education, Mastuana Sahib, Sangrur, 148001, Punjab, India
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Sánchez C, Bueno-Orovio A, Wettwer E, Loose S, Simon J, Ravens U, Pueyo E, Rodriguez B. Inter-subject variability in human atrial action potential in sinus rhythm versus chronic atrial fibrillation. PLoS One 2014; 9:e105897. [PMID: 25157495 PMCID: PMC4144914 DOI: 10.1371/journal.pone.0105897] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Accepted: 07/26/2014] [Indexed: 02/07/2023] Open
Abstract
AIMS Human atrial electrophysiology exhibits high inter-subject variability in both sinus rhythm (SR) and chronic atrial fibrillation (cAF) patients. Variability is however rarely investigated in experimental and theoretical electrophysiological studies, thus hampering the understanding of its underlying causes but also its implications in explaining differences in the response to disease and treatment. In our study, we aim at investigating the ability of populations of human atrial cell models to capture the inter-subject variability in action potential (AP) recorded in 363 patients both under SR and cAF conditions. METHODS AND RESULTS Human AP recordings in atrial trabeculae (n = 469) from SR and cAF patients were used to calibrate populations of computational SR and cAF atrial AP models. Three populations of over 2000 sampled models were generated, based on three different human atrial AP models. Experimental calibration selected populations of AP models yielding AP with morphology and duration in range with experimental recordings. Populations using the three original models can mimic variability in experimental AP in both SR and cAF, with median conductance values in SR for most ionic currents deviating less than 30% from their original peak values. All cAF populations show similar variations in G(K1), G(Kur) and G(to), consistent with AF-related remodeling as reported in experiments. In all SR and cAF model populations, inter-subject variability in I(K1) and I(NaK) underlies variability in APD90, variability in I(Kur), I(CaL) and I(NaK) modulates variability in APD50 and combined variability in Ito and I(Kur) determines variability in APD20. The large variability in human atrial AP triangulation is mostly determined by I(K1) and either I(NaK) or I(NaCa) depending on the model. CONCLUSION Experimentally-calibrated human atrial AP models populations mimic AP variability in SR and cAF patient recordings, and identify potential ionic determinants of inter-subject variability in human atrial AP duration and morphology in SR versus cAF.
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Affiliation(s)
- Carlos Sánchez
- Biosignal Interpretation and Computational Simulation (BSICoS), Aragón Institute of Engineering Research (I3A) and Aragón Health Research Institute (IIS), University of Zaragoza, Zaragoza, Spain
- Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Zaragoza, Spain
- Department of Computer Science, University of Oxford, Oxford, United Kingdom
| | | | - Erich Wettwer
- Department of Pharmacology and Toxicology, Dresden University of Technology, Dresden, Germany
| | - Simone Loose
- Department of Pharmacology and Toxicology, Dresden University of Technology, Dresden, Germany
| | - Jana Simon
- Department of Pharmacology and Toxicology, Dresden University of Technology, Dresden, Germany
| | - Ursula Ravens
- Department of Pharmacology and Toxicology, Dresden University of Technology, Dresden, Germany
| | - Esther Pueyo
- Biosignal Interpretation and Computational Simulation (BSICoS), Aragón Institute of Engineering Research (I3A) and Aragón Health Research Institute (IIS), University of Zaragoza, Zaragoza, Spain
- Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Zaragoza, Spain
| | - Blanca Rodriguez
- Department of Computer Science, University of Oxford, Oxford, United Kingdom
- * E-mail:
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Cummins MA, Dalal PJ, Bugana M, Severi S, Sobie EA. Comprehensive analyses of ventricular myocyte models identify targets exhibiting favorable rate dependence. PLoS Comput Biol 2014; 10:e1003543. [PMID: 24675446 PMCID: PMC3967944 DOI: 10.1371/journal.pcbi.1003543] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Accepted: 02/13/2014] [Indexed: 12/02/2022] Open
Abstract
Reverse rate dependence is a problematic property of antiarrhythmic drugs that prolong the cardiac action potential (AP). The prolongation caused by reverse rate dependent agents is greater at slow heart rates, resulting in both reduced arrhythmia suppression at fast rates and increased arrhythmia risk at slow rates. The opposite property, forward rate dependence, would theoretically overcome these parallel problems, yet forward rate dependent (FRD) antiarrhythmics remain elusive. Moreover, there is evidence that reverse rate dependence is an intrinsic property of perturbations to the AP. We have addressed the possibility of forward rate dependence by performing a comprehensive analysis of 13 ventricular myocyte models. By simulating populations of myocytes with varying properties and analyzing population results statistically, we simultaneously predicted the rate-dependent effects of changes in multiple model parameters. An average of 40 parameters were tested in each model, and effects on AP duration were assessed at slow (0.2 Hz) and fast (2 Hz) rates. The analysis identified a variety of FRD ionic current perturbations and generated specific predictions regarding their mechanisms. For instance, an increase in L-type calcium current is FRD when this is accompanied by indirect, rate-dependent changes in slow delayed rectifier potassium current. A comparison of predictions across models identified inward rectifier potassium current and the sodium-potassium pump as the two targets most likely to produce FRD AP prolongation. Finally, a statistical analysis of results from the 13 models demonstrated that models displaying minimal rate-dependent changes in AP shape have little capacity for FRD perturbations, whereas models with large shape changes have considerable FRD potential. This can explain differences between species and between ventricular cell types. Overall, this study provides new insights, both specific and general, into the determinants of AP duration rate dependence, and illustrates a strategy for the design of potentially beneficial antiarrhythmic drugs. Several drugs intended to treat cardiac arrhythmias have failed because of unfavorable rate-dependent properties. That is, the drugs fail to alter electrical activity at fast heart rates, where this would be beneficial, but they do affect electrical activity at slow rates, where this is unwanted. In targeted studies, several agents have been shown to exhibit these unfavorable properties, suggesting that these rate-dependent responses may be intrinsic to ventricular muscle. To determine whether drugs with desirable rate-dependent properties could be rationally designed, we performed comprehensive and systematic analyses of several heart cell models. These analyses calculated the rate-dependent properties of changes in any model parameter, thereby generating simultaneously a large number of model predictions. The analyses showed that targets with favorable rate-dependent properties could indeed be identified, and further simulations uncovered the mechanisms underlying these behaviors. Moreover, a quantitative comparison of results obtained in different models provided new insight in why a given drug applied to different species, or to different tissue types, might produce different rate-dependent behaviors. Overall this study shows how a comprehensive and systematic approach to heart cell models can both identify novel targets and produce more general insight into rate-dependent alterations to cardiac electrical activity.
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Affiliation(s)
- Megan A. Cummins
- Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Pavan J. Dalal
- Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | | | | | - Eric A. Sobie
- Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
- * E-mail:
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