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Dartsch RC, Kraut S, Mayer T, Gabel A, Dietrich A, Weissmann N, Fuchs B, Knoepp F. Use of FRET-Sensor 'Mermaid' to Detect Subtle Changes in Membrane Potential of Primary Mouse PASMCs. Cells 2024; 13:1070. [PMID: 38920698 PMCID: PMC11202191 DOI: 10.3390/cells13121070] [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: 05/29/2024] [Revised: 06/17/2024] [Accepted: 06/18/2024] [Indexed: 06/27/2024] Open
Abstract
Subtle changes in the membrane potential of pulmonary arterial smooth muscle cells (PASMCs) are pivotal for controlling pulmonary vascular tone, e.g., for initiating Hypoxic Pulmonary Vasoconstriction, a vital mechanism of the pulmonary circulation. In our study, we evaluated the ability of the fluorescence resonance energy transfer (FRET)-based voltage-sensor Mermaid to detect such subtle changes in membrane potential. Mouse PASMCs were isolated and transduced with Mermaid-encoding lentiviral vectors before the acceptor/donor emission ratio was assessed via live cell FRET-imaging. Mermaid's sensitivity was tested by applying specific potassium chloride (KCl) concentrations. These KCl concentrations were previously validated by patch clamp recordings to induce depolarization with predefined amplitudes that physiologically occur in PASMCs. Mermaid's emission ratio dose-dependently increased upon depolarization with KCl. However, Mermaid formed unspecific intracellular aggregates, which limited the usefulness of this voltage sensor. When analyzing the membrane rim only to circumvent these unspecific signals, Mermaid was not suitable to resolve subtle changes in the membrane potential of ≤10 mV. In summary, we found Mermaid to be a suitable alternative for reliably detecting qualitative membrane voltage changes of more than 10 mV in primary mouse PASMCs. However, one should be aware of the limitations associated with this voltage sensor.
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Affiliation(s)
- Ruth C. Dartsch
- Cardiopulmonary Institute (CPI), Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Justus-Liebig-University, 35392 Giessen, Germany
| | - Simone Kraut
- Cardiopulmonary Institute (CPI), Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Justus-Liebig-University, 35392 Giessen, Germany
| | - Tim Mayer
- Walther-Straub-Institute for Pharmacology and Toxicology, Member of the German Center for Lung Research (DZL), Ludwig-Maximilians University, 80539 Munich, Germany; (T.M.)
| | - Andreas Gabel
- Cardiopulmonary Institute (CPI), Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Justus-Liebig-University, 35392 Giessen, Germany
| | - Alexander Dietrich
- Walther-Straub-Institute for Pharmacology and Toxicology, Member of the German Center for Lung Research (DZL), Ludwig-Maximilians University, 80539 Munich, Germany; (T.M.)
| | - Norbert Weissmann
- Cardiopulmonary Institute (CPI), Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Justus-Liebig-University, 35392 Giessen, Germany
| | - Beate Fuchs
- Cardiopulmonary Institute (CPI), Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Justus-Liebig-University, 35392 Giessen, Germany
| | - Fenja Knoepp
- Cardiopulmonary Institute (CPI), Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Justus-Liebig-University, 35392 Giessen, Germany
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LaFosse PK, Zhou Z, O'Rawe JF, Friedman NG, Scott VM, Deng Y, Histed MH. Single-cell optogenetics reveals attenuation-by-suppression in visual cortical neurons. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.09.13.557650. [PMID: 37745464 PMCID: PMC10515908 DOI: 10.1101/2023.09.13.557650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/26/2023]
Abstract
The relationship between neurons' input and spiking output is central to brain computation. Studies in vitro and in anesthetized animals suggest nonlinearities emerge in cells' input-output (activation) functions as network activity increases, yet how neurons transform inputs in vivo has been unclear. Here, we characterize cortical principal neurons' activation functions in awake mice using two-photon optogenetics. We deliver fixed inputs at the soma while neurons' activity varies with sensory stimuli. We find responses to fixed optogenetic input are nearly unchanged as neurons are excited, reflecting a linear response regime above neurons' resting point. In contrast, responses are dramatically attenuated by suppression. This attenuation is a powerful means to filter inputs arriving to suppressed cells, privileging other inputs arriving to excited neurons. These results have two major implications. First, somatic neural activation functions in vivo accord with the activation functions used in recent machine learning systems. Second, neurons' IO functions can filter sensory inputs - not only do sensory stimuli change neurons' spiking outputs, but these changes also affect responses to input, attenuating responses to some inputs while leaving others unchanged.
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Affiliation(s)
- Paul K LaFosse
- Intramural Program, National Institute of Mental Health, National Institutes of Health, Bethesda, MD USA 20892
- NIH-University of Maryland Graduate Partnerships Program, Bethesda, MD USA 20892
- Neuroscience and Cognitive Science Program, University of Maryland College Park, College Park, MD USA 20742
| | - Zhishang Zhou
- Intramural Program, National Institute of Mental Health, National Institutes of Health, Bethesda, MD USA 20892
| | - Jonathan F O'Rawe
- Intramural Program, National Institute of Mental Health, National Institutes of Health, Bethesda, MD USA 20892
| | - Nina G Friedman
- Intramural Program, National Institute of Mental Health, National Institutes of Health, Bethesda, MD USA 20892
- NIH-University of Maryland Graduate Partnerships Program, Bethesda, MD USA 20892
- Neuroscience and Cognitive Science Program, University of Maryland College Park, College Park, MD USA 20742
| | - Victoria M Scott
- Intramural Program, National Institute of Mental Health, National Institutes of Health, Bethesda, MD USA 20892
| | - Yanting Deng
- Intramural Program, National Institute of Mental Health, National Institutes of Health, Bethesda, MD USA 20892
| | - Mark H Histed
- Intramural Program, National Institute of Mental Health, National Institutes of Health, Bethesda, MD USA 20892
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3
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Mondal R, Vaissier Welborn V. Dynamics accelerate the kinetics of ion diffusion through channels: Continuous-time random walk models beyond the mean field approximation. J Chem Phys 2024; 160:144109. [PMID: 38597306 DOI: 10.1063/5.0188469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Accepted: 03/14/2024] [Indexed: 04/11/2024] Open
Abstract
Ion channels are proteins that play a significant role in physiological processes, including neuronal excitability and signal transduction. However, the precise mechanisms by which these proteins facilitate ion diffusion through cell membranes are not well understood. This is because experimental techniques to characterize ion channel activity operate on a time scale too large to understand the role of the various protein conformations on diffusion. Meanwhile, computational approaches operate on a time scale too short to rationalize the observed behavior at the microscopic scale. In this paper, we present a continuous-time random walk model that aims to bridge the scales between the atomistic models of ion channels and the experimental measurement of their conductance. We show how diffusion slows down in complex systems by using 3D lattices that map out the pore geometry of two channels: Nav1.7 and gramicidin. We also introduce spatial and dynamic site disorder to account for system heterogeneity beyond the mean field approximation. Computed diffusion coefficients show that an increase in spatial disorder slows down diffusion kinetics, while dynamic disorder has the opposite effect. Our results imply that microscopic or phenomenological models based on the potential of mean force data overlook the functional importance of protein dynamics on ion diffusion through channels.
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Affiliation(s)
- Ronnie Mondal
- Department of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, USA
- Macromolecules Innovation Institute, Virginia Tech, Blacksburg, Virginia 24061, USA
| | - Valerie Vaissier Welborn
- Department of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, USA
- Macromolecules Innovation Institute, Virginia Tech, Blacksburg, Virginia 24061, USA
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Seibertz F, Voigt N. High-throughput methods for cardiac cellular electrophysiology studies: the road to personalized medicine. Am J Physiol Heart Circ Physiol 2024; 326:H938-H949. [PMID: 38276947 PMCID: PMC11279751 DOI: 10.1152/ajpheart.00599.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 01/22/2024] [Accepted: 01/22/2024] [Indexed: 01/27/2024]
Abstract
Personalized medicine refers to the tailored application of medical treatment at an individual level, considering the specific genotype or phenotype of each patient for targeted therapy. In the context of cardiovascular diseases, implementing personalized medicine is challenging due to the high costs involved and the slow pace of identifying the pathogenicity of genetic variants, deciphering molecular mechanisms of disease, and testing treatment approaches. Scalable cellular models such as human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) serve as useful in vitro tools that reflect individual patient genetics and retain clinical phenotypes. High-throughput functional assessment of these constructs is necessary to rapidly assess cardiac pathogenicity and test new therapeutics if personalized medicine is to become a reality. High-throughput photometry recordings of single cells coupled with potentiometric probes offer cost-effective alternatives to traditional patch-clamp assessments of cardiomyocyte action potential characteristics. Importantly, automated patch-clamp (APC) is rapidly emerging in the pharmaceutical industry and academia as a powerful method to assess individual membrane-bound ionic currents and ion channel biophysics over multiple cells in parallel. Now amenable to primary cell and hiPSC-CM measurement, APC represents an exciting leap forward in the characterization of a multitude of molecular mechanisms that underlie clinical cardiac phenotypes. This review provides a summary of state-of-the-art high-throughput electrophysiological techniques to assess cardiac electrophysiology and an overview of recent works that successfully integrate these methods into basic science research that could potentially facilitate future implementation of personalized medicine at a clinical level.
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Affiliation(s)
- Fitzwilliam Seibertz
- Institute of Pharmacology and Toxicology, University Medical Center Göttingen, Georg-August University Göttingen, Göttingen, Germany
- German Center for Cardiovascular Research (DZHK), partner site Göttingen, Göttingen, Germany
- Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells," Georg-August University Göttingen, Göttingen, Germany
- Nanion Technologies, GmbH, Munich, Germany
| | - Niels Voigt
- Institute of Pharmacology and Toxicology, University Medical Center Göttingen, Georg-August University Göttingen, Göttingen, Germany
- German Center for Cardiovascular Research (DZHK), partner site Göttingen, Göttingen, Germany
- Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells," Georg-August University Göttingen, Göttingen, Germany
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Zhang X, Wang X, Li Y, Zhang Y, Zhu H, Xie C, Zhou Y, Shen Y, Tong J. Characterization of Retinal VIP-Amacrine Cell Development During the Critical Period. Cell Mol Neurobiol 2024; 44:19. [PMID: 38315298 PMCID: PMC10844409 DOI: 10.1007/s10571-024-01452-x] [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: 10/24/2023] [Accepted: 01/08/2024] [Indexed: 02/07/2024]
Abstract
Retinal vasoactive intestinal peptide amacrine cells (VIP-ACs) play an important role in various retinal light-mediated pathological processes related to different developmental ocular diseases and even mental disorders. It is important to characterize the developmental changes in VIP-ACs to further elucidate their mechanisms of circuit function. We bred VIP-Cre mice with Ai14 and Ai32 to specifically label retinal VIP-ACs. The VIP-AC soma and spine density generally increased, from postnatal day (P)0 to P35, reaching adult levels at P14 and P28, respectively. The VIP-AC soma density curve was different with the VIP-AC spine density curve. The total retinal VIP content reached a high level plateau at P14 but was decreased in adults. From P14 to P16, the resting membrane potential (RMP) became more negative, and the input resistance decreased. Cell membrane capacitance (MC) showed three peaks at P7, P12 and P16. The RMP and MC reached a stable level similar to the adult level at P18, whereas input resistance reached a stable level at P21. The percentage of sustained voltage-dependent potassium currents peaked at P16 and remained stable thereafter. The spontaneous excitatory postsynaptic current and spontaneous inhibitory postsynaptic current frequencies and amplitudes, as well as charge transfer, peaked at P12 to P16; however, there were also secondary peaks at different time points. In conclusion, we found that the second, third and fourth weeks after birth were important periods of VIP-AC development. Many developmental changes occurred around eye opening. The development of soma, dendrite and electrophysiological properties showed uneven dynamics of progression. Cell differentiation may contribute to soma development whereas the changes of different ion channels may play important role for spine development.
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Affiliation(s)
- Xuhong Zhang
- Department of Ophthalmology, The First Affiliated Hospital of Medical College, Zhejiang University, No.79 Qingchun Road, Shangcheng District, Hangzhou, 310003, Zhejiang, China
| | - Xiaoyu Wang
- Department of Ophthalmology, The First Affiliated Hospital of Medical College, Zhejiang University, No.79 Qingchun Road, Shangcheng District, Hangzhou, 310003, Zhejiang, China
- Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brain Medicine, Zhejiang University, No.866 Yuhangtang Road, Xihu District, Hangzhou, 310058, Zhejiang, China
| | - Yanqing Li
- Department of Ophthalmology, The First Affiliated Hospital of Medical College, Zhejiang University, No.79 Qingchun Road, Shangcheng District, Hangzhou, 310003, Zhejiang, China
| | - Yingying Zhang
- Department of Ophthalmology, The First Affiliated Hospital of Medical College, Zhejiang University, No.79 Qingchun Road, Shangcheng District, Hangzhou, 310003, Zhejiang, China
- Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brain Medicine, Zhejiang University, No.866 Yuhangtang Road, Xihu District, Hangzhou, 310058, Zhejiang, China
| | - Hong Zhu
- Department of Ophthalmology, The First Affiliated Hospital of Medical College, Zhejiang University, No.79 Qingchun Road, Shangcheng District, Hangzhou, 310003, Zhejiang, China
| | - Chen Xie
- Department of Ophthalmology, The First Affiliated Hospital of Medical College, Zhejiang University, No.79 Qingchun Road, Shangcheng District, Hangzhou, 310003, Zhejiang, China
| | - Yudong Zhou
- Department of Ophthalmology, The First Affiliated Hospital of Medical College, Zhejiang University, No.79 Qingchun Road, Shangcheng District, Hangzhou, 310003, Zhejiang, China
- Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brain Medicine, Zhejiang University, No.866 Yuhangtang Road, Xihu District, Hangzhou, 310058, Zhejiang, China
| | - Ye Shen
- Department of Ophthalmology, The First Affiliated Hospital of Medical College, Zhejiang University, No.79 Qingchun Road, Shangcheng District, Hangzhou, 310003, Zhejiang, China.
| | - Jianping Tong
- Department of Ophthalmology, The First Affiliated Hospital of Medical College, Zhejiang University, No.79 Qingchun Road, Shangcheng District, Hangzhou, 310003, Zhejiang, China.
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Abrasheva VO, Kovalenko SG, Slotvitsky M, Romanova SА, Aitova AA, Frolova S, Tsvelaya V, Syunyaev RA. Human sodium current voltage-dependence at physiological temperature measured by coupling a patch-clamp experiment to a mathematical model. J Physiol 2024; 602:633-661. [PMID: 38345560 DOI: 10.1113/jp285162] [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: 06/16/2023] [Accepted: 01/02/2024] [Indexed: 02/20/2024] Open
Abstract
Voltage-gated Na+ channels are crucial to action potential propagation in excitable tissues. Because of the high amplitude and rapid activation of the Na+ current, voltage-clamp measurements are very challenging and are usually performed at room temperature. In this study, we measured Na+ current voltage-dependence in stem cell-derived cardiomyocytes at physiological temperature. While the apparent activation and inactivation curves, measured as the dependence of current amplitude on voltage, fall within the range reported in previous studies, we identified a systematic error in our measurements. This error is caused by the deviation of the membrane potential from the command potential of the amplifier. We demonstrate that it is possible to account for this artifact using computer simulation of the patch-clamp experiment. We obtained surprising results through patch-clamp model optimization: a half-activation of -11.5 mV and a half-inactivation of -87 mV. Although the half-activation deviates from previous research, we demonstrate that this estimate reproduces the conduction velocity dependence on extracellular potassium concentration. KEY POINTS: Voltage-gated Na+ currents play a crucial role in excitable tissues including neurons, cardiac and skeletal muscle. Measurement of Na+ current is challenging because of its high amplitude and rapid kinetics, especially at physiological temperature. We have used the patch-clamp technique to measure human Na+ current voltage-dependence in human induced pluripotent stem cell-derived cardiomyocytes. The patch-clamp data were processed by optimization of the model accounting for voltage-clamp experiment artifacts, revealing a large difference between apparent parameters of Na+ current and the results of the optimization. We conclude that actual Na+ current activation is extremely depolarized in comparison to previous studies. The new Na+ current model provides a better understanding of action potential propagation; we demonstrate that it explains propagation in hyperkalaemic conditions.
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Affiliation(s)
| | - Sandaara G Kovalenko
- Moscow Institute of Physics and Technology, Moscow, Russia
- M. F. Vladimirsky Moscow Regional Research Clinical Institute, Moscow, Russia
- ITMO University, St Petersburg, Russia
| | - Mihail Slotvitsky
- Moscow Institute of Physics and Technology, Moscow, Russia
- M. F. Vladimirsky Moscow Regional Research Clinical Institute, Moscow, Russia
- ITMO University, St Petersburg, Russia
| | - Serafima А Romanova
- Moscow Institute of Physics and Technology, Moscow, Russia
- M. F. Vladimirsky Moscow Regional Research Clinical Institute, Moscow, Russia
| | - Aleria A Aitova
- Moscow Institute of Physics and Technology, Moscow, Russia
- M. F. Vladimirsky Moscow Regional Research Clinical Institute, Moscow, Russia
- ITMO University, St Petersburg, Russia
| | - Sheida Frolova
- Moscow Institute of Physics and Technology, Moscow, Russia
- M. F. Vladimirsky Moscow Regional Research Clinical Institute, Moscow, Russia
| | - Valeria Tsvelaya
- Moscow Institute of Physics and Technology, Moscow, Russia
- M. F. Vladimirsky Moscow Regional Research Clinical Institute, Moscow, Russia
- ITMO University, St Petersburg, Russia
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7
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Huang CLH, Lei M. Cardiomyocyte electrophysiology and its modulation: current views and future prospects. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220160. [PMID: 37122224 PMCID: PMC10150219 DOI: 10.1098/rstb.2022.0160] [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: 01/16/2023] [Accepted: 03/10/2023] [Indexed: 05/02/2023] Open
Abstract
Normal and abnormal cardiac rhythms are of key physiological and clinical interest. This introductory article begins from Sylvio Weidmann's key historic 1950s microelectrode measurements of cardiac electrophysiological activity and Singh & Vaughan Williams's classification of cardiotropic targets. It then proceeds to introduce the insights into cardiomyocyte function and its regulation that subsequently emerged and their therapeutic implications. We recapitulate the resulting view that surface membrane electrophysiological events underlying cardiac excitation and its initiation, conduction and recovery constitute the final common path for the cellular mechanisms that impinge upon this normal or abnormal cardiac electrophysiological activity. We then consider progress in the more recently characterized successive regulatory hierarchies involving Ca2+ homeostasis, excitation-contraction coupling and autonomic G-protein signalling and their often reciprocal interactions with the surface membrane events, and their circadian rhythms. Then follow accounts of longer-term upstream modulation processes involving altered channel expression, cardiomyocyte energetics and hypertrophic and fibrotic cardiac remodelling. Consideration of these developments introduces each of the articles in this Phil. Trans. B theme issue. The findings contained in these articles translate naturally into recent classifications of cardiac electrophysiological targets and drug actions, thereby encouraging future iterations of experimental cardiac electrophysiological discovery, and testing directed towards clinical management. This article is part of the theme issue 'The heartbeat: its molecular basis and physiological mechanisms'.
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Affiliation(s)
- Christopher L.-H. Huang
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge CB2 3EG, UK
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, UK
| | - Ming Lei
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
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8
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Garneau AP, Slimani S, Haydock L, Nsimba-Batomene TR, Préfontaine FCM, Lavoie MM, Tremblay LE, Fiola MJ, Mac-Way F, Isenring P. Molecular mechanisms, physiological roles, and therapeutic implications of ion fluxes in bone cells: Emphasis on the cation-Cl - cotransporters. J Cell Physiol 2022; 237:4356-4368. [PMID: 36125923 PMCID: PMC10087713 DOI: 10.1002/jcp.30879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Revised: 08/25/2022] [Accepted: 09/01/2022] [Indexed: 11/11/2022]
Abstract
Bone turnover diseases are exceptionally prevalent in human and come with a high burden on physical health. While these diseases are associated with a variety of risk factors and causes, they are all characterized by common denominators, that is, abnormalities in the function or number of osteoblasts, osteoclasts, and/or osteocytes. As such, much effort has been deployed in the recent years to understand the signaling mechanisms of bone cell proliferation and differentiation with the objectives of exploiting the intermediates involved as therapeutic preys. Ion transport systems at the external and in the intracellular membranes of osteoblasts and osteoclasts also play an important role in bone turnover by coordinating the movement of Ca2+ , PO4 2- , and H+ ions in and out of the osseous matrix. Even if they sustain the terminal steps of osteoformation and osteoresorption, they have been the object of very little attention in the last several years. Members of the cation-Cl- cotransporter (CCC) family are among the systems at work as they are expressed in bone cells, are known to affect the activity of Ca2+ -, PO4 2- -, and H+ -dependent transport systems and have been linked to bone mass density variation in human. In this review, the roles played by the CCCs in bone remodeling will be discussed in light of recent developments and their potential relevance in the treatment of skeletal disorders.
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Affiliation(s)
- Alexandre P Garneau
- Department of Medicine, Nephrology Research Group, Laval University, Québec, Québec, Canada.,Service de Néphrologie-Transplantation Rénale Adultes, Hôpital Necker-Enfants Malades, AP-HP, Inserm U1151, Université Paris Cité, rue de Sèvres, Paris, France
| | - Samira Slimani
- Department of Medicine, Nephrology Research Group, Laval University, Québec, Québec, Canada
| | - Ludwig Haydock
- Department of Medicine, Nephrology Research Group, Laval University, Québec, Québec, Canada
| | | | | | - Mathilde M Lavoie
- Department of Medicine, Nephrology Research Group, Laval University, Québec, Québec, Canada
| | - Laurence E Tremblay
- Department of Medicine, Nephrology Research Group, Laval University, Québec, Québec, Canada
| | - Marie-Jeanne Fiola
- Department of Medicine, Nephrology Research Group, Laval University, Québec, Québec, Canada
| | - Fabrice Mac-Way
- Department of Medicine, Nephrology Research Group, Laval University, Québec, Québec, Canada
| | - Paul Isenring
- Department of Medicine, Nephrology Research Group, Laval University, Québec, Québec, Canada
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9
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Electromechanical integrated recording of single cardiomyocyte in situ by multimodal microelectrode biosensing system. Biosens Bioelectron 2022; 212:114387. [DOI: 10.1016/j.bios.2022.114387] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Revised: 04/15/2022] [Accepted: 05/15/2022] [Indexed: 11/22/2022]
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10
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Govorunova EG, Sineshchekov OA, Brown LS, Spudich JL. Biophysical characterization of light-gated ion channels using planar automated patch clamp. Front Mol Neurosci 2022; 15:976910. [PMID: 36017077 PMCID: PMC9396214 DOI: 10.3389/fnmol.2022.976910] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Accepted: 07/21/2022] [Indexed: 01/09/2023] Open
Abstract
Channelrhodopsins (ChRs) are proteins that guide phototaxis in protists and exhibit light-gated channel conductance when their genes are heterologously expressed in mammalian cells. ChRs are widely used as molecular tools to control neurons and cardiomyocytes with light (optogenetics). Cation- and anion-selective ChRs (CCRs and ACRs, respectively) enable stimulation and inhibition of neuronal activity by depolarization and hyperpolarization of the membrane, respectively. More than 400 natural ChR variants have been identified so far, and high-throughput polynucleotide sequencing projects add many more each year. However, electrophysiological characterization of new ChRs lags behind because it is mostly done by time-consuming manual patch clamp (MPC). Here we report using a high-throughput automated patch clamp (APC) platform, SyncroPatch 384i from Nanion Technologies, for ChR research. We find that this instrument can be used for determination of the light intensity dependence and current-voltage relationships in ChRs and discuss its advantages and limitations.
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Affiliation(s)
- Elena G. Govorunova
- Department of Biochemistry and Molecular Biology, Center for Membrane Biology, The University of Texas Health Science Center at Houston McGovern Medical School, Houston, TX, United States
| | - Oleg A. Sineshchekov
- Department of Biochemistry and Molecular Biology, Center for Membrane Biology, The University of Texas Health Science Center at Houston McGovern Medical School, Houston, TX, United States
| | - Leonid S. Brown
- Biophysics Interdepartmental Group, Department of Physics, University of Guelph, Guelph, ON, Canada
| | - John L. Spudich
- Department of Biochemistry and Molecular Biology, Center for Membrane Biology, The University of Texas Health Science Center at Houston McGovern Medical School, Houston, TX, United States
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Silicon Nitride-Based Micro-Apertures Coated with Parylene for the Investigation of Pore Proteins Fused in Free-Standing Lipid Bilayers. MEMBRANES 2022; 12:membranes12030309. [PMID: 35323784 PMCID: PMC8954132 DOI: 10.3390/membranes12030309] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 02/25/2022] [Accepted: 03/07/2022] [Indexed: 12/21/2022]
Abstract
In this work, we present a microsystem setup for performing sensitive biological membrane translocation measurements. Thin free-standing synthetic bilayer lipid membranes (BLM) were constructed in microfabricated silicon nitride apertures (<100 µm in diameter), conformal coated with Parylene (Parylene-C or Parylene-AF4). Within these BLMs, electrophysiological measurements were conducted to monitor the behavior of different pore proteins. Two approaches to integrate pore-forming proteins into the membrane were applied: direct reconstitution and reconstitution via outer membrane vesicles (OMVs) released from Gram-negative bacteria. The advantage of utilizing OMVs is that the pore proteins remain in their native lipid and lipopolysaccharide (LPS) environment, representing a more natural state compared to the usage of fused purified pore proteins. Multiple aperture chips can be easily assembled in the 3d-printed holder to conduct parallel membrane transport investigations. Moreover, well defined microfabricated apertures are achievable with very high reproducibility. The presented microsystem allows the investigation of fast gating events (down to 1 ms), pore blocking by an antibiotic, and gating events of small pores (amplitude of approx. 3 pA).
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Fischer-Holzhausen S, Yamamoto K, Fjeldstad MP, Maleckar MM. Probing the Putative Role of K ATP Channels and Biological Variability in a Mathematical Model of Chondrocyte Electrophysiology. Bioelectricity 2021. [DOI: 10.1089/bioe.2021.0034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
| | - Kei Yamamoto
- Department of Mathematics, University of Oslo, Oslo, Norway
- Computational Physiology, Simula Research Laboratory, Oslo, Norway
| | | | - Mary M. Maleckar
- Computational Physiology, Simula Research Laboratory, Oslo, Norway
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13
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Penzkofer A, Silapetere A, Hegemann P. Photocycle dynamics of the Archaerhodopsin 3 based fluorescent voltage sensor Archon2. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 2021; 225:112331. [PMID: 34688164 DOI: 10.1016/j.jphotobiol.2021.112331] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2021] [Revised: 09/21/2021] [Accepted: 10/05/2021] [Indexed: 11/28/2022]
Abstract
The retinal photocycle dynamics of the fluorescent voltage sensor Archon2 in pH 8 Tris buffer was studied. Archon2 is a mutant of Archaerhodopsin 3 (Arch) from Halorubrum sodomense obtained by a robotic multidimensional directed evolution approach (Archon2 = Arch T56P-P60S-T80P-D95H-T99S-T116I-F161V-T183I-L197I-A225C). The samples were photo-excited to the first absorption band of the protonated retinal Schiff base (PRSB) Ret_586 (absorption maximum at λmax = 586 nm, excitation wavelengths λexc = 590 nm and 632.8 nm). The photocycle dynamics were studied by recording absorption spectra during light exposure and after light exposure. Ret_586 photoisomerized to Ret_535 (main component) and Ret_485 (minor component). Ret_535 backward photoisomerized to Ret_586 in light-adapted state (named Ret_586la) and partly deprotonated to neutral retinal Schiff base (RSB) Ret_372 in light adapted state (named Ret_372la, same isomer form as Ret_535). After excitation light switch-off Ret_372la recovered to Ret_372 in dark-adapted state (Ret_372da) which slowly re-protonated to Ret_535, and Ret_535 slowly isomerized back to Ret_586 in dark-adapted state (Ret_586da). Photocycle schemes and reaction coordinate diagrams are developed and photocycle parameters are determined.
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Affiliation(s)
- Alfons Penzkofer
- Fakultät für Physik, Universität Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany.
| | - Arita Silapetere
- Experimentelle Biophysik, Institut für Biologie, Humboldt Universität zu Berlin, Invalidenstraße 42, D-10115 Berlin, Germany
| | - Peter Hegemann
- Experimentelle Biophysik, Institut für Biologie, Humboldt Universität zu Berlin, Invalidenstraße 42, D-10115 Berlin, Germany
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14
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Van de Sande DV, Kopljar I, Maaike A, Teisman A, Gallacher DJ, Bart L, Snyders DJ, Leybaert L, Lu HR, Labro AJ. The resting membrane potential of hSC-CM in a syncytium is more hyperpolarised than that of isolated cells. Channels (Austin) 2021; 15:239-252. [PMID: 33465001 PMCID: PMC7817136 DOI: 10.1080/19336950.2021.1871815] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 11/20/2020] [Accepted: 12/31/2020] [Indexed: 01/11/2023] Open
Abstract
Human-induced pluripotent stem cell (hiPSC) and stem cell (hSC) derived cardiomyocytes (CM) are gaining popularity as in vitro model for cardiology and pharmacology studies. A remaining flaw of these cells, as shown by single-cell electrophysiological characterization, is a more depolarized resting membrane potential (RMP) compared to native CM. Most reports attribute this to a lower expression of the Kir2.1 potassium channel that generates the IK1 current. However, most RMP recordings are obtained from isolated hSC/hiPSC-CMs whereas in a more native setting these cells are interconnected with neighboring cells by connexin-based gap junctions, forming a syncytium. Hereby, these cells are electrically connected and the total pool of IK1 increases. Therefore, the input resistance (Ri) of interconnected cells is lower than that of isolated cells. During patch clamp experiments pipettes need to be well attached or sealed to the cell, which is reflected in the seal resistance (Rs), because a nonspecific ionic current can leak through this pipette-cell contact or seal and balance out small currents within the cell such as IK1. By recording the action potential of isolated hSC-CMs and that of hSC-CMs cultured in small monolayers, we show that the RMP of hSC-CMs in monolayer is approximately -20 mV more hyperpolarized compared to isolated cells. Accordingly, adding carbenoxolone, a connexin channel blocker, isolates the cell that is patch clamped from its neighboring cells of the monolayer and depolarizes the RMP. The presented data show that the recorded RMP of hSC-CMs in a syncytium is more negative than that determined from isolated hSC/hiPSC-CMs, most likely because the active pool of Kir2.1 channels increased.
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Affiliation(s)
| | - Ivan Kopljar
- Global Safety Pharmacology, Non-Clinical Safety, Janssen R&D, Beerse, Belgium
| | - Alaerts Maaike
- Centre of Medical Genetics, University of Antwerp, Antwerp, Belgium
| | - Ard Teisman
- Global Safety Pharmacology, Non-Clinical Safety, Janssen R&D, Beerse, Belgium
| | - David J. Gallacher
- Global Safety Pharmacology, Non-Clinical Safety, Janssen R&D, Beerse, Belgium
| | - Loeys Bart
- Centre of Medical Genetics, University of Antwerp, Antwerp, Belgium
| | - Dirk J. Snyders
- Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
| | - Luc Leybaert
- Department of Basic and Applied Medical Sciences, Ghent University, Ghent, Belgium
| | - Hua Rong Lu
- Global Safety Pharmacology, Non-Clinical Safety, Janssen R&D, Beerse, Belgium
| | - Alain J. Labro
- Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
- Department of Basic and Applied Medical Sciences, Ghent University, Ghent, Belgium
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15
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Fang J, Wei X, Li H, Hu N, Liu X, Xu D, Zhang T, Wan H, Wang P, Xie X. Cardiomyocyte electrical-mechanical synchronized model for high-content, dose-quantitative and time-dependent drug assessment. MICROSYSTEMS & NANOENGINEERING 2021; 7:26. [PMID: 34567740 PMCID: PMC8433219 DOI: 10.1038/s41378-021-00247-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2020] [Revised: 01/13/2021] [Accepted: 01/31/2021] [Indexed: 05/16/2023]
Abstract
Cardiovascular diseases have emerged as a significant threat to human health. However, drug development is a time-consuming and costly process, and few drugs pass the preclinical assessment of safety and efficacy. The existing patch-clamp, Ca2+ imaging, and microelectrode array technologies in cardiomyocyte models for drug preclinical screening have suffered from issues of low throughput, limited long-term assessment, or inability to synchronously and correlatively analyze electrical and mechanical signals. Here, we develop a high-content, dose-quantitative and time-dependent drug assessment platform based on an electrical-mechanical synchronized (EMS) biosensing system. This microfabricated EMS can record both firing potential (FP) and mechanical beating (MB) signals from cardiomyocytes and extract a variety of characteristic parameters from these two signals (FP-MB) for further analysis. This system was applied to test typical ion channel drugs (lidocaine and isradipine), and the dynamic responses of cardiomyocytes to the tested drugs were recorded and analyzed. The high-throughput characteristics of the system can facilitate simultaneous experiments on a large number of samples. Furthermore, a database of various cardiac drugs can be established by heat map analysis for rapid and effective screening of drugs. The EMS biosensing system is highly promising as a powerful tool for the preclinical development of new medicines.
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Affiliation(s)
- Jiaru Fang
- The First Affiliated Hospital of Sun Yat-Sen University; School of Electronics and Information Technology, Guangdong Province Key Laboratory of Display Material and Technology, Sun Yat-sen University, Guangzhou, 510006 China
| | - Xinwei Wei
- Biosensor National Special Laboratory, Key Laboratory of Biomedical Engineering of Ministry of Education, Department of Biomedical Engineering, Zhejiang University, Hangzhou, 310027 China
| | - Hongbo Li
- The First Affiliated Hospital of Sun Yat-Sen University; School of Electronics and Information Technology, Guangdong Province Key Laboratory of Display Material and Technology, Sun Yat-sen University, Guangzhou, 510006 China
| | - Ning Hu
- The First Affiliated Hospital of Sun Yat-Sen University; School of Electronics and Information Technology, Guangdong Province Key Laboratory of Display Material and Technology, Sun Yat-sen University, Guangzhou, 510006 China
- State Key Laboratory of Transducer Technology, Chinese Academy of Sciences, Shanghai, 200050 China
| | - Xingxing Liu
- The First Affiliated Hospital of Sun Yat-Sen University; School of Electronics and Information Technology, Guangdong Province Key Laboratory of Display Material and Technology, Sun Yat-sen University, Guangzhou, 510006 China
| | - Dongxin Xu
- The First Affiliated Hospital of Sun Yat-Sen University; School of Electronics and Information Technology, Guangdong Province Key Laboratory of Display Material and Technology, Sun Yat-sen University, Guangzhou, 510006 China
| | - Tao Zhang
- School of Biomedical Engineering, Sun Yat-sen University, Guangzhou, 510006 China
| | - Hao Wan
- Biosensor National Special Laboratory, Key Laboratory of Biomedical Engineering of Ministry of Education, Department of Biomedical Engineering, Zhejiang University, Hangzhou, 310027 China
- State Key Laboratory of Transducer Technology, Chinese Academy of Sciences, Shanghai, 200050 China
| | - Ping Wang
- Biosensor National Special Laboratory, Key Laboratory of Biomedical Engineering of Ministry of Education, Department of Biomedical Engineering, Zhejiang University, Hangzhou, 310027 China
- State Key Laboratory of Transducer Technology, Chinese Academy of Sciences, Shanghai, 200050 China
| | - Xi Xie
- The First Affiliated Hospital of Sun Yat-Sen University; School of Electronics and Information Technology, Guangdong Province Key Laboratory of Display Material and Technology, Sun Yat-sen University, Guangzhou, 510006 China
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16
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Ahmed T, van den Driesche S, Bafna JA, Oellers M, Hemmler R, Gall K, Wagner R, Winterhalter M, Vellekoop MJ. Rapid lipid bilayer membrane formation on Parylene coated apertures to perform ion channel analyses. Biomed Microdevices 2020; 22:32. [PMID: 32355998 PMCID: PMC7192868 DOI: 10.1007/s10544-020-0473-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
We present a chip design allowing rapid and robust lipid bilayer (LBL) membrane formation using a Parylene coated thin silicon nitride aperture. After bilayer formation, single membrane channels can be reconstituted and characterized by electrophysiology. The ability for robust reconstitution will allow parallelization and enhanced screening of small molecule drugs acting on or permeating across the membrane channel. The aperture was realized on a microfabricated silicon nitride membrane by using standard clean-room fabrication processes. To ensure the lipid bilayer formation, the nitride membrane was coated with a hydrophobic and biocompatible Parylene layer. We tested both Parylene-C and Parylene-AF4. The contact angle measurements on both Parylene types showed very good hydrophobic properties and affinity to lipids. No precoating of the Parylene with an organic solvent is needed to make the aperture lipophilic, in contradiction to Teflon membranes. The chips can be easily placed in an array utilizing a 3D printed platform. Experiments show repetitive LBL formation and destruction (more than 6 times) within a very short time (few seconds). Through measurements we have established that the LBL layers are very thin. This allows the investigation of the fusion process of membrane proteins i.e. outer membrane protein (OmpF) in the LBL within a few minutes.
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Affiliation(s)
- Tanzir Ahmed
- Institute for Microsensors, -actuators and -systems (IMSAS), University of Bremen, Microsystems Center Bremen (MCB), Bremen, Germany
| | - Sander van den Driesche
- Institute for Microsensors, -actuators and -systems (IMSAS), University of Bremen, Microsystems Center Bremen (MCB), Bremen, Germany
| | - Jayesh Arun Bafna
- Department of Life Sciences and Chemistry, Jacobs University Bremen, Bremen, Germany
| | - Martin Oellers
- Institute for Microsensors, -actuators and -systems (IMSAS), University of Bremen, Microsystems Center Bremen (MCB), Bremen, Germany
| | | | | | - Richard Wagner
- Department of Life Sciences and Chemistry, Jacobs University Bremen, Bremen, Germany
| | - Mathias Winterhalter
- Department of Life Sciences and Chemistry, Jacobs University Bremen, Bremen, Germany
| | - Michael J. Vellekoop
- Institute for Microsensors, -actuators and -systems (IMSAS), University of Bremen, Microsystems Center Bremen (MCB), Bremen, Germany
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17
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Becker N, Horváth A, De Boer T, Fabbri A, Grad C, Fertig N, George M, Obergrussberger A. Automated Dynamic Clamp for Simulation of I
K1
in Human Induced Pluripotent Stem Cell–Derived Cardiomyocytes in Real Time Using Patchliner Dynamite
8. ACTA ACUST UNITED AC 2019; 88:e70. [DOI: 10.1002/cpph.70] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
| | | | - Teun De Boer
- Department of Medical PhysiologyUniversity Medical Center Utrecht Utrecht The Netherlands
| | - Alan Fabbri
- Department of Medical PhysiologyUniversity Medical Center Utrecht Utrecht The Netherlands
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18
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Penzkofer A, Silapetere A, Hegemann P. Absorption and Emission Spectroscopic Investigation of the Thermal Dynamics of the Archaerhodopsin 3 Based Fluorescent Voltage Sensor QuasAr1. Int J Mol Sci 2019; 20:E4086. [PMID: 31438573 PMCID: PMC6747118 DOI: 10.3390/ijms20174086] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2019] [Revised: 08/15/2019] [Accepted: 08/16/2019] [Indexed: 12/13/2022] Open
Abstract
QuasAr1 is a fluorescent voltage sensor derived from Archaerhodopsin 3 (Arch) of Halorubrum sodomense by directed evolution. Here we report absorption and emission spectroscopic studies of QuasAr1 in Tris buffer at pH 8. Absorption cross-section spectra, fluorescence quantum distributions, fluorescence quantum yields, and fluorescence excitation spectra were determined. The thermal stability of QuasAr1 was studied by long-time attenuation coefficient measurements at room temperature (23 ± 2 °C) and at 2.5 ± 0.5 °C. The apparent melting temperature was determined by stepwise sample heating up and cooling down (obtained apparent melting temperature: 65 ± 3 °C). In the protein melting process the originally present protonated retinal Schiff base (PRSB) with absorption maximum at 580 nm converted to de-protonated retinal Schiff base (RSB) with absorption maximum at 380 nm. Long-time storage of QuasAr1 at temperatures around 2.5 °C and around 23 °C caused gradual protonated retinal Schiff base isomer changes to other isomer conformations, de-protonation to retinal Schiff base isomers, and apoprotein structure changes showing up in ultraviolet absorption increase. Reaction coordinate schemes are presented for the thermal protonated retinal Schiff base isomerizations and deprotonations in parallel with the dynamic apoprotein restructurings.
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Affiliation(s)
- Alfons Penzkofer
- Fakultät für Physik, Universität Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany.
| | - Arita Silapetere
- Experimentelle Biophysik, Institut für Biologie, Humboldt Universität zu Berlin, Invalidenstraße 42, D-10115 Berlin, Germany
| | - Peter Hegemann
- Experimentelle Biophysik, Institut für Biologie, Humboldt Universität zu Berlin, Invalidenstraße 42, D-10115 Berlin, Germany
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19
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Maleckar MM, Clark RB, Votta B, Giles WR. The Resting Potential and K + Currents in Primary Human Articular Chondrocytes. Front Physiol 2018; 9:974. [PMID: 30233381 PMCID: PMC6131720 DOI: 10.3389/fphys.2018.00974] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Accepted: 07/03/2018] [Indexed: 11/23/2022] Open
Abstract
Human transplant programs provide significant opportunities for detailed in vitro assessments of physiological properties of selected tissues and cell types. We present a semi-quantitative study of the fundamental electrophysiological/biophysical characteristics of human chondrocytes, focused on K+ transport mechanisms, and their ability to regulate to the resting membrane potential, Em. Patch clamp studies on these enzymatically isolated human chondrocytes reveal consistent expression of at least three functionally distinct K+ currents, as well as transient receptor potential (TRP) currents. The small size of these cells and their exceptionally low current densities present significant technical challenges for electrophysiological recordings. These limitations have been addressed by parallel development of a mathematical model of these K+ and TRP channel ion transfer mechanisms in an attempt to reveal their contributions to Em. In combination, these experimental results and simulations yield new insights into: (i) the ionic basis for Em and its expected range of values; (ii) modulation of Em by the unique articular joint extracellular milieu; (iii) some aspects of TRP channel mediated depolarization-secretion coupling; (iv) some of the essential biophysical principles that regulate K+ channel function in “chondrons.” The chondron denotes the chondrocyte and its immediate extracellular compartment. The presence of discrete localized surface charges and associated zeta potentials at the chondrocyte surface are regulated by cell metabolism and can modulate interactions of chondrocytes with the extracellular matrix. Semi-quantitative analysis of these factors in chondrocyte/chondron function may yield insights into progressive osteoarthritis.
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Affiliation(s)
- Mary M Maleckar
- Simula Research Laboratory, Center for Biomedical Computing and Center for Cardiological Innovation, Oslo, Norway.,Allen Institute for Cell Science, Seattle, WA, United States
| | - Robert B Clark
- Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
| | | | - Wayne R Giles
- Faculties of Kinesiology and Medicine, University of Calgary, Calgary, AB, Canada
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20
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Iwata T, Nagatani H, Osakai T. Determination of the Electrostatic Potential of Oil-in-Water Emulsion Droplets by Combined Use of Two Membrane Potential-Sensitive Dyes. ANAL SCI 2018; 33:813-819. [PMID: 28690259 DOI: 10.2116/analsci.33.813] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The fluorescence behaviors of potential-sensitive dyes including anionic DiBAC4(3) (denoted by dye A), DiSBAC2(3) (dye B), and zwitterionic di-4-ANEPPS (dye C) were studied in oil-in-water (O/W) emulsions. In this study, the equilibrium Galvani potential difference (ΔOWφeq) of the O/W-emulsion droplets was controlled by changing the ratio of the concentrations of electrolytes added to the O (=1,2-dichloroethane) and W phases. When using an adequate combination of the dyes, i.e., B and C, we could observe that the ratio of their fluorescence peak intensities was changed from 1.08 to 1.38, depending on the change of (ΔOWφeq from 26 to 73 mV. It is desirable to apply this method to study the potential-dependent ion or electron-transfer reactions occurring at vesicles or liposomes, and also to biomembranes.
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Affiliation(s)
- Tomoya Iwata
- Department of Chemistry, Graduate School of Science, Kobe University
| | - Hirohisa Nagatani
- Faculty of Chemistry, Institute of Science and Engineering, Kanazawa University
| | - Toshiyuki Osakai
- Department of Chemistry, Graduate School of Science, Kobe University
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21
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Horváth A, Lemoine MD, Löser A, Mannhardt I, Flenner F, Uzun AU, Neuber C, Breckwoldt K, Hansen A, Girdauskas E, Reichenspurner H, Willems S, Jost N, Wettwer E, Eschenhagen T, Christ T. Low Resting Membrane Potential and Low Inward Rectifier Potassium Currents Are Not Inherent Features of hiPSC-Derived Cardiomyocytes. Stem Cell Reports 2018; 10:822-833. [PMID: 29429959 PMCID: PMC5918194 DOI: 10.1016/j.stemcr.2018.01.012] [Citation(s) in RCA: 76] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 01/12/2018] [Accepted: 01/15/2018] [Indexed: 11/18/2022] Open
Abstract
Human induced pluripotent stem cell (hiPSC) cardiomyocytes (CMs) show less negative resting membrane potential (RMP), which is attributed to small inward rectifier currents (IK1). Here, IK1 was measured in hiPSC-CMs (proprietary and commercial cell line) cultured as monolayer (ML) or 3D engineered heart tissue (EHT) and, for direct comparison, in CMs from human right atrial (RA) and left ventricular (LV) tissue. RMP was measured in isolated cells and intact tissues. IK1 density in ML- and EHT-CMs from the proprietary line was similar to LV and RA, respectively. IK1 density in EHT-CMs from the commercial line was 2-fold smaller than in the proprietary line. RMP in EHT of both lines was similar to RA and LV. Repolarization fraction and IK,ACh response discriminated best between RA and LV and indicated predominantly ventricular phenotype in hiPSC-CMs/EHT. The data indicate that IK1 is not necessarily low in hiPSC-CMs, and technical issues may underlie low RMP in hiPSC-CMs.
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Affiliation(s)
- András Horváth
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Institut für Experimentelle Pharmakologie und Toxikologie, Universitätsklinikum Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany; Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, 6721 Szeged, Hungary
| | - Marc D Lemoine
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Institut für Experimentelle Pharmakologie und Toxikologie, Universitätsklinikum Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; Department of Cardiology-Electrophysiology, University Heart Center Hamburg, 20246 Hamburg, Germany
| | - Alexandra Löser
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Institut für Experimentelle Pharmakologie und Toxikologie, Universitätsklinikum Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - Ingra Mannhardt
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Institut für Experimentelle Pharmakologie und Toxikologie, Universitätsklinikum Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - Frederik Flenner
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Institut für Experimentelle Pharmakologie und Toxikologie, Universitätsklinikum Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - Ahmet Umur Uzun
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Institut für Experimentelle Pharmakologie und Toxikologie, Universitätsklinikum Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - Christiane Neuber
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Institut für Experimentelle Pharmakologie und Toxikologie, Universitätsklinikum Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - Kaja Breckwoldt
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Institut für Experimentelle Pharmakologie und Toxikologie, Universitätsklinikum Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - Arne Hansen
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Institut für Experimentelle Pharmakologie und Toxikologie, Universitätsklinikum Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - Evaldas Girdauskas
- Department of Cardiovascular Surgery, University Heart Center Hamburg, 20246 Hamburg, Germany
| | - Hermann Reichenspurner
- Department of Cardiovascular Surgery, University Heart Center Hamburg, 20246 Hamburg, Germany
| | - Stephan Willems
- Department of Cardiology-Electrophysiology, University Heart Center Hamburg, 20246 Hamburg, Germany
| | - Norbert Jost
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, 6721 Szeged, Hungary
| | - Erich Wettwer
- Institute of Pharmacology, University Duisburg-Essen, 45122 Essen, Germany
| | - Thomas Eschenhagen
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Institut für Experimentelle Pharmakologie und Toxikologie, Universitätsklinikum Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - Torsten Christ
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Institut für Experimentelle Pharmakologie und Toxikologie, Universitätsklinikum Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany.
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22
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Lemoine MD, Mannhardt I, Breckwoldt K, Prondzynski M, Flenner F, Ulmer B, Hirt MN, Neuber C, Horváth A, Kloth B, Reichenspurner H, Willems S, Hansen A, Eschenhagen T, Christ T. Human iPSC-derived cardiomyocytes cultured in 3D engineered heart tissue show physiological upstroke velocity and sodium current density. Sci Rep 2017; 7:5464. [PMID: 28710467 PMCID: PMC5511281 DOI: 10.1038/s41598-017-05600-w] [Citation(s) in RCA: 127] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Accepted: 06/12/2017] [Indexed: 12/16/2022] Open
Abstract
Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM) are a promising tool for drug testing and modelling genetic disorders. Abnormally low upstroke velocity is a current limitation. Here we investigated the use of 3D engineered heart tissue (EHT) as a culture method with greater resemblance to human heart tissue in comparison to standard technique of 2D monolayer (ML) format. INa was measured in ML or EHT using the standard patch-clamp technique. INa density was ~1.8 fold larger in EHT (-18.5 ± 1.9 pA/pF; n = 17) than in ML (-10.3 ± 1.2 pA/pF; n = 23; p < 0.001), approaching densities reported for human CM. Inactivation kinetics, voltage dependency of steady-state inactivation and activation of INa did not differ between EHT and ML and were similar to previously reported values for human CM. Action potential recordings with sharp microelectrodes showed similar upstroke velocities in EHT (219 ± 15 V/s, n = 13) and human left ventricle tissue (LV, 253 ± 7 V/s, n = 25). EHT showed a greater resemblance to LV in CM morphology and subcellular NaV1.5 distribution. INa in hiPSC-CM showed similar biophysical properties as in human CM. The EHT format promotes INa density and action potential upstroke velocity of hiPSC-CM towards adult values, indicating its usefulness as a model for excitability of human cardiac tissue.
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Affiliation(s)
- Marc D Lemoine
- Department of Cardiology-Electrophysiology, University Heart Center, Hamburg, Germany. .,Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany. .,DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, Hamburg, Germany.
| | - Ingra Mannhardt
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, Hamburg, Germany
| | - Kaja Breckwoldt
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, Hamburg, Germany
| | - Maksymilian Prondzynski
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, Hamburg, Germany
| | - Frederik Flenner
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, Hamburg, Germany
| | - Bärbel Ulmer
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, Hamburg, Germany
| | - Marc N Hirt
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, Hamburg, Germany
| | - Christiane Neuber
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, Hamburg, Germany
| | - András Horváth
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Benjamin Kloth
- Department of Cardiovascular Surgery, University Heart Center, Hamburg, Germany
| | | | - Stephan Willems
- Department of Cardiology-Electrophysiology, University Heart Center, Hamburg, Germany.,DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, Hamburg, Germany
| | - Arne Hansen
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, Hamburg, Germany
| | - Thomas Eschenhagen
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, Hamburg, Germany
| | - Torsten Christ
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany. .,DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, Hamburg, Germany.
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23
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Clark RB, Schmidt TA, Sachse FB, Boyle D, Firestein GS, Giles WR. Cellular electrophysiological principles that modulate secretion from synovial fibroblasts. J Physiol 2017; 595:635-645. [PMID: 27079855 DOI: 10.1113/jp270209] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Accepted: 03/02/2016] [Indexed: 12/29/2022] Open
Abstract
Rheumatoid arthritis (RA) is a progressive disease that affects both pediatric and adult populations. The cellular basis for RA has been investigated extensively using animal models, human tissues and isolated cells in culture. However, many aspects of its aetiology and molecular mechanisms remain unknown. Some of the electrophysiological principles that regulate secretion of essential lubricants (hyaluronan and lubricin) and cytokines from synovial fibroblasts have been identified. Data sets describing the main types of ion channels that are expressed in human synovial fibroblast preparations have begun to provide important new insights into the interplay among: (i) ion fluxes, (ii) Ca2+ release from the endoplasmic reticulum, (iii) intercellular coupling, and (iv) both transient and longer duration changes in synovial fibroblast membrane potential. A combination of this information, knowledge of similar patterns of responses in cells that regulate the immune system, and the availability of adult human synovial fibroblasts are likely to provide new pathophysiological insights.
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Affiliation(s)
- R B Clark
- Faculties of Kinesiology and Medicine, University of Calgary, Calgary, Canada, T2N 1N4
| | - T A Schmidt
- Faculties of Kinesiology and Engineering, University of Calgary, Calgary, Canada, T2N 1N4
| | - F B Sachse
- Department of Bioengineering and Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, USA
| | - D Boyle
- Department of Medicine, University of California, San Diego, CA, USA
| | - G S Firestein
- Department of Medicine, University of California, San Diego, CA, USA
| | - W R Giles
- Faculties of Kinesiology and Medicine, University of Calgary, Calgary, Canada, T2N 1N4
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24
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Uzun AU, Mannhardt I, Breckwoldt K, Horváth A, Johannsen SS, Hansen A, Eschenhagen T, Christ T. Ca(2+)-Currents in Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes Effects of Two Different Culture Conditions. Front Pharmacol 2016; 7:300. [PMID: 27672365 PMCID: PMC5018497 DOI: 10.3389/fphar.2016.00300] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Accepted: 08/25/2016] [Indexed: 11/13/2022] Open
Abstract
Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM) provide a unique opportunity to study human heart physiology and pharmacology and repair injured hearts. The suitability of hiPSC-CM critically depends on how closely they share physiological properties of human adult cardiomyocytes (CM). Here we investigated whether a 3D engineered heart tissue (EHT) culture format favors maturation and addressed the L-type Ca2+-current (ICa,L) as a readout. The results were compared with hiPSC-CM cultured in conventional monolayer (ML) and to our previous data from human adult atrial and ventricular CM obtained when identical patch-clamp protocols were used. HiPSC-CM were two- to three-fold smaller than adult CM, independently of culture format [capacitance ML 45 ± 1 pF (n = 289), EHT 45 ± 1 pF (n = 460), atrial CM 87 ± 3 pF (n = 196), ventricular CM 126 ± 8 pF (n = 50)]. Only 88% of ML cells showed ICa, but all EHT. Basal ICa density was 10 ± 1 pA/pF (n = 207) for ML and 12 ± 1 pA/pF (n = 361) for EHT and was larger than in adult CM [7 ± 1 pA/pF (p < 0.05, n = 196) for atrial CM and 6 ± 1 pA/pF (p < 0.05, n = 47) for ventricular CM]. However, ML and EHT showed robust T-type Ca2+-currents (ICa,T). While (−)-Bay K 8644, that activates ICa,L directly, increased ICa,Lto the same extent in ML and EHT, β1- and β2-adrenoceptor effects were marginal in ML, but of same size as (−)-Bay K 8644 in EHT. The opposite was true for serotonin receptors. Sensitivity to β1 and β2-adrenoceptor stimulation was the same in EHT as in adult CM (−logEC50: 5.9 and 6.1 for norepinephrine (NE) and epinephrine (Epi), respectively), but very low concentrations of Rp-8-Br-cAMPS were sufficient to suppress effects (−logEC50: 5.3 and 5.3 respectively for NE and Epi). Taken together, hiPSC-CM express ICa,L at the same density as human adult CM, but, in contrast, possess robust ICa,T. Increased effects of catecholamines in EHT suggest more efficient maturation.
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Affiliation(s)
- Ahmet U Uzun
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-EppendorfHamburg, Germany; Partner Site Hamburg/Kiel/Lübeck, German Centre for Cardiovascular Research (DZHK)Hamburg, Germany
| | - Ingra Mannhardt
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-EppendorfHamburg, Germany; Partner Site Hamburg/Kiel/Lübeck, German Centre for Cardiovascular Research (DZHK)Hamburg, Germany
| | - Kaja Breckwoldt
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-EppendorfHamburg, Germany; Partner Site Hamburg/Kiel/Lübeck, German Centre for Cardiovascular Research (DZHK)Hamburg, Germany
| | - András Horváth
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-EppendorfHamburg, Germany; Partner Site Hamburg/Kiel/Lübeck, German Centre for Cardiovascular Research (DZHK)Hamburg, Germany; Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of SzegedSzeged, Hungary
| | - Silke S Johannsen
- Partner Site Hamburg/Kiel/Lübeck, German Centre for Cardiovascular Research (DZHK)Hamburg, Germany; Department of General and Interventional Cardiology, University Heart Center HamburgHamburg, Germany
| | - Arne Hansen
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-EppendorfHamburg, Germany; Partner Site Hamburg/Kiel/Lübeck, German Centre for Cardiovascular Research (DZHK)Hamburg, Germany
| | - Thomas Eschenhagen
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-EppendorfHamburg, Germany; Partner Site Hamburg/Kiel/Lübeck, German Centre for Cardiovascular Research (DZHK)Hamburg, Germany
| | - Torsten Christ
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-EppendorfHamburg, Germany; Partner Site Hamburg/Kiel/Lübeck, German Centre for Cardiovascular Research (DZHK)Hamburg, Germany
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25
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Giles WR, Noble D. Rigorous Phenotyping of Cardiac iPSC Preparations Requires Knowledge of Their Resting Potential(s). Biophys J 2016; 110:278-80. [PMID: 26745430 DOI: 10.1016/j.bpj.2015.06.070] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Revised: 05/22/2015] [Accepted: 06/03/2015] [Indexed: 02/08/2023] Open
Affiliation(s)
- Wayne R Giles
- Faculties of Kinesiology and Medicine, University of Calgary, Calgary, Alberta, Canada.
| | - Denis Noble
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
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26
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Cervera J, Alcaraz A, Mafe S. Bioelectrical Signals and Ion Channels in the Modeling of Multicellular Patterns and Cancer Biophysics. Sci Rep 2016; 6:20403. [PMID: 26841954 PMCID: PMC4740742 DOI: 10.1038/srep20403] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2015] [Accepted: 01/06/2016] [Indexed: 01/08/2023] Open
Abstract
Bioelectrical signals and ion channels are central to spatial patterns in cell ensembles, a problem of fundamental interest in positional information and cancer processes. We propose a model for electrically connected cells based on simple biological concepts: i) the membrane potential of a single cell characterizes its electrical state; ii) the long-range electrical coupling of the multicellular ensemble is realized by a network of gap junction channels between neighboring cells; and iii) the spatial distribution of an external biochemical agent can modify the conductances of the ion channels in a cell membrane and the multicellular electrical state. We focus on electrical effects in small multicellular ensembles, ignoring slow diffusional processes. The spatio-temporal patterns obtained for the local map of cell electric potentials illustrate the normalization of regions with abnormal cell electrical states. The effects of intercellular coupling and blocking of specific channels on the electrical patterns are described. These patterns can regulate the electrically-induced redistribution of charged nanoparticles over small regions of a model tissue. The inclusion of bioelectrical signals provides new insights for the modeling of cancer biophysics because collective multicellular states show electrical coupling mechanisms that are not readily deduced from biochemical descriptions at the individual cell level.
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Affiliation(s)
- Javier Cervera
- Dept. de Termodinàmica, Facultat de Física, Universitat de València, E-46100 Burjassot, Spain
| | - Antonio Alcaraz
- Dept. de Física, Laboratori de Biofísica Molecular, Universitat “Jaume I”, E-12080 Castelló, Spain
| | - Salvador Mafe
- Dept. de Termodinàmica, Facultat de Física, Universitat de València, E-46100 Burjassot, Spain
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27
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Computational Approaches to Understanding the Role of Fibroblast-Myocyte Interactions in Cardiac Arrhythmogenesis. BIOMED RESEARCH INTERNATIONAL 2015; 2015:465714. [PMID: 26601107 PMCID: PMC4637154 DOI: 10.1155/2015/465714] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Revised: 04/10/2015] [Accepted: 04/29/2015] [Indexed: 11/18/2022]
Abstract
The adult heart is composed of a dense network of cardiomyocytes surrounded by nonmyocytes, the most
abundant of which are cardiac fibroblasts. Several cardiac diseases, such as myocardial infarction or dilated
cardiomyopathy, are associated with an increased density of fibroblasts, that is, fibrosis. Fibroblasts play a
significant role in the development of electrical and mechanical dysfunction of the heart; however the underlying
mechanisms are only partially understood. One widely studied mechanism suggests that fibroblasts produce
excess extracellular matrix, resulting in collagenous septa. These collagenous septa slow propagation, cause
zig-zag conduction paths, and decouple cardiomyocytes resulting in a substrate for arrhythmia. Another
emerging mechanism suggests that fibroblasts promote arrhythmogenesis through direct electrical interactions
with cardiomyocytes via gap junctions. Due to the challenges of investigating fibroblast-myocyte coupling in
native cardiac tissue, computational modeling and in vitro experiments have facilitated the investigation into the
mechanisms underlying fibroblast-mediated changes in cardiomyocyte action potential morphology, conduction
velocity, spontaneous excitability, and vulnerability to reentry. In this paper, we summarize the major findings of
the existing computational studies investigating the implications of fibroblast-myocyte interactions in the normal
and diseased heart. We then present investigations from our group into the potential role of voltage-dependent
gap junctions in fibroblast-myocyte interactions.
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28
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Cervera J, Manzanares JA, Mafe S. Electrical coupling in ensembles of nonexcitable cells: modeling the spatial map of single cell potentials. J Phys Chem B 2015; 119:2968-78. [PMID: 25622192 DOI: 10.1021/jp512900x] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
We analyze the coupling of model nonexcitable (non-neural) cells assuming that the cell membrane potential is the basic individual property. We obtain this potential on the basis of the inward and outward rectifying voltage-gated channels characteristic of cell membranes. We concentrate on the electrical coupling of a cell ensemble rather than on the biochemical and mechanical characteristics of the individual cells, obtain the map of single cell potentials using simple assumptions, and suggest procedures to collectively modify this spatial map. The response of the cell ensemble to an external perturbation and the consequences of cell isolation, heterogeneity, and ensemble size are also analyzed. The results suggest that simple coupling mechanisms can be significant for the biophysical chemistry of model biomolecular ensembles. In particular, the spatiotemporal map of single cell potentials should be relevant for the uptake and distribution of charged nanoparticles over model cell ensembles and the collective properties of droplet networks incorporating protein ion channels inserted in lipid bilayers.
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Affiliation(s)
- Javier Cervera
- Departament de Termodinàmica, Universitat de València , E-46100 Burjassot, Spain
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29
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Cervera J, Alcaraz A, Mafe S. Membrane potential bistability in nonexcitable cells as described by inward and outward voltage-gated ion channels. J Phys Chem B 2014; 118:12444-50. [PMID: 25286866 DOI: 10.1021/jp508304h] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The membrane potential of nonexcitable cells, defined as the electrical potential difference between the cell cytoplasm and the extracellular environment when the current is zero, is controlled by the individual electrical conductance of different ion channels. In particular, inward- and outward-rectifying voltage-gated channels are crucial for cell hyperpolarization/depolarization processes, being amenable to direct physical study. High (in absolute value) negative membrane potentials are characteristic of terminally differentiated cells, while low membrane potentials are found in relatively depolarized, more plastic cells (e.g., stem, embryonic, and cancer cells). We study theoretically the hyperpolarized and depolarized values of the membrane potential, as well as the possibility to obtain a bistability behavior, using simplified models for the ion channels that regulate this potential. The bistability regions, which are defined in the multidimensional state space determining the cell state, can be relevant for the understanding of the different model cell states and the transitions between them, which are triggered by changes in the external environment.
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Affiliation(s)
- Javier Cervera
- Departament de Termodinàmica, Universitat de València , E-46100 Burjassot, Spain
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30
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Koivumäki JT, Clark RB, Belke D, Kondo C, Fedak PWM, Maleckar MMC, Giles WR. Na(+) current expression in human atrial myofibroblasts: identity and functional roles. Front Physiol 2014; 5:275. [PMID: 25147525 PMCID: PMC4124488 DOI: 10.3389/fphys.2014.00275] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Accepted: 07/07/2014] [Indexed: 12/19/2022] Open
Abstract
In the mammalian heart fibroblasts have important functional roles in both healthy conditions and diseased states. During pathophysiological challenges, a closely related myofibroblast cell population emerges, and can have distinct, significant roles. Recently, it has been reported that human atrial myofibroblasts can express a Na+ current, INa. Some of the biophysical properties and molecular features suggest that this INa is due to expression of Nav 1.5, the same Na+ channel α subunit that generates the predominant INa in myocytes from adult mammalian heart. In principle, expression of Nav 1.5 could give rise to regenerative action potentials in the fibroblasts/myofibroblasts. This would suggest an active as opposed to passive role for fibroblasts/myofibroblasts in both the “trigger” and the “substrate” components of cardiac rhythm disturbances. Our goals in this preliminary study were: (i) to confirm and extend the electrophysiological characterization of INa in a human atrial fibroblast/myofibroblast cell population maintained in conventional 2-D tissue culture; (ii) to identify key molecular properties of the α and β subunits of these Na+ channel(s); (iii) to define the biophysical and pharmacological properties of this INa; (iv) to integrate the available multi-disciplinary data, and attempt to illustrate its functional consequences, using a mathematical model in which the human atrial myocyte is coupled via connexins to fixed numbers of fibroblasts/myofibroblasts in a syncytial arrangement. Our experimental findings confirm that a significant fraction (approximately 40–50%) of these human atrial myofibroblasts can express INa. However, our data suggest that INa may be generated by a combination of Nav 1.9, Nav 1.2, and Nav 1.5. Our results, when complemented with mathematical modeling, provide a background for re-evaluating pharmacological management of supraventricular rhythm disorders, e.g., persistent atrial fibrillation.
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Affiliation(s)
- Jussi T Koivumäki
- Simula Research Laboratory, Center for Biomedical Computing and Center for Cardiological Innovation Oslo, Norway
| | - Robert B Clark
- Faculty of Kinesiology, University of Calgary Calgary, AB, Canada
| | - Darrell Belke
- Faculty of Kinesiology, University of Calgary Calgary, AB, Canada
| | - Colleen Kondo
- Faculty of Kinesiology, University of Calgary Calgary, AB, Canada
| | - Paul W M Fedak
- Division of Cardiothoracic Surgery, Department of Cardiac Sciences, University of Calgary Calgary, AB, Canada
| | - Mary M C Maleckar
- Simula Research Laboratory, Center for Biomedical Computing and Center for Cardiological Innovation Oslo, Norway
| | - Wayne R Giles
- Faculty of Kinesiology, University of Calgary Calgary, AB, Canada
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31
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Combined use of two membrane-potential-sensitive dyes for determination of the Galvani potential difference across a biomimetic oil/water interface. Anal Bioanal Chem 2014; 406:3407-14. [DOI: 10.1007/s00216-014-7776-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Revised: 03/17/2014] [Accepted: 03/17/2014] [Indexed: 11/25/2022]
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32
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Mobasheri A, Lewis R, Ferreira-Mendes A, Rufino A, Dart C, Barrett-Jolley R. Potassium channels in articular chondrocytes. Channels (Austin) 2012; 6:416-25. [PMID: 23064164 PMCID: PMC3536726 DOI: 10.4161/chan.22340] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Chondrocytes are the resident cells of cartilage, which synthesize and maintain the extracellular matrix. The range of known potassium channels expressed by these unique cells is continually increasing. Since chondrocytes are non-excitable, and do not need to be repolarized following action potentials, the function of potassium channels in these cells has, until recently, remained completely unknown. However, recent advances in both traditional physiology and “omic” technologies have enhanced our knowledge and understanding of the chondrocyte channelome. A large number of potassium channels have been identified and a number of putative, but credible, functions have been proposed. Members of each of the potassium channel sub-families (calcium activated, inward rectifier, voltage-gated and tandem pore) have all been identified. Mechanotransduction, cell volume regulation, apoptosis and chondrogenesis all appear to involve potassium channels. Since evidence suggests that potassium channel gene transcription is altered in osteoarthritis, future studies are needed that investigate potassium channels as potential cellular biomarkers and therapeutic targets for treatment of degenerative joint conditions.
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Affiliation(s)
- Ali Mobasheri
- Musculoskeletal Research Group, Division of Veterinary Medicine, Faculty of Medicine and Health Sciences, The University of Nottingham, Sutton Bonington Campus, Sutton Bonington, Leicestershire, UK. ali.
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