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Nayak AK, Das SL, Misbah C. Endothelial calcium dynamics elicited by ATP release from red blood cells. Sci Rep 2024; 14:13550. [PMID: 38866785 DOI: 10.1038/s41598-024-63306-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Accepted: 05/27/2024] [Indexed: 06/14/2024] Open
Abstract
Red blood cells (RBCs) exhibit an interesting response to hydrodynamic flow, releasing adenosine triphosphate (ATP). Subsequently, these liberated ATP molecules initiate a crucial interaction with endothelial cells (ECs), thereby setting off a cascade involving the release of calcium ions (Ca2 + ). Ca2 + exerts control over a plethora of cellular functions, and acts as a mediator for dilation and contraction of blood vessel walls. This study focuses on the relationship between RBC dynamics and Ca2 + dynamics, based on numerical simulations under Poiseuille flow within a linear two-dimensional channel. It is found that the concentration of ATP depends upon a variety of factors, including RBC density, channel width, and the vigor of the flow. The results of our investigation reveals several features. Firstly, the peak amplitude of Ca2 + per EC escalates in direct proportion to the augmentation of RBC concentration. Secondly, increasing the flow strength induces a reduction in the time taken to reach the peak of Ca2 + concentration, under the condition of a constant channel width. Additionally, when flow strength remains constant, an increase in channel width corresponds to an elevation in calcium peak amplitude, coupled with a decrease in peak time. This implies that Ca2 + signals should transition from relatively unconstrained channels to more confined pathways within real vascular networks. This notion gains support from our examination of calcium propagation in a linear channel. In this scenario, the localized Ca2 + release initiates a propagating wave that gradually encompasses the entire channel. Notably, our computed propagation speed agrees with observations.
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Affiliation(s)
| | - Sovan Lal Das
- Physical and Chemical Biology Laboratory, and Department of Mechanical Engineering, Indian Institute of Technology Palakkad, Palakkad, 678623, India
| | - Chaouqi Misbah
- CNRS, LIPhy, Université Grenoble Alpes, 38000, Grenoble, France.
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2
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Moccia F, Brunetti V, Soda T, Berra-Romani R, Scarpellino G. Cracking the Endothelial Calcium (Ca 2+) Code: A Matter of Timing and Spacing. Int J Mol Sci 2023; 24:16765. [PMID: 38069089 PMCID: PMC10706333 DOI: 10.3390/ijms242316765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 11/16/2023] [Accepted: 11/24/2023] [Indexed: 12/18/2023] Open
Abstract
A monolayer of endothelial cells lines the innermost surface of all blood vessels, thereby coming into close contact with every region of the body and perceiving signals deriving from both the bloodstream and parenchymal tissues. An increase in intracellular Ca2+ concentration ([Ca2+]i) is the main mechanism whereby vascular endothelial cells integrate the information conveyed by local and circulating cues. Herein, we describe the dynamics and spatial distribution of endothelial Ca2+ signals to understand how an array of spatially restricted (at both the subcellular and cellular levels) Ca2+ signals is exploited by the vascular intima to fulfill this complex task. We then illustrate how local endothelial Ca2+ signals affect the most appropriate vascular function and are integrated to transmit this information to more distant sites to maintain cardiovascular homeostasis. Vasorelaxation and sprouting angiogenesis were selected as an example of functions that are finely tuned by the variable spatio-temporal profile endothelial Ca2+ signals. We further highlighted how distinct Ca2+ signatures regulate the different phases of vasculogenesis, i.e., proliferation and migration, in circulating endothelial precursors.
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Affiliation(s)
- Francesco Moccia
- Laboratory of General Physiology, Department of Biology and Biotechnology “L. Spallanzani”, University of Pavia, 27100 Pavia, Italy; (V.B.); (G.S.)
| | - Valentina Brunetti
- Laboratory of General Physiology, Department of Biology and Biotechnology “L. Spallanzani”, University of Pavia, 27100 Pavia, Italy; (V.B.); (G.S.)
| | - Teresa Soda
- Department of Health Sciences, University of Magna Graecia, 88100 Catanzaro, Italy;
| | - Roberto Berra-Romani
- Department of Biomedicine, School of Medicine, Benemérita Universidad Autónoma de Puebla, Puebla 72410, Mexico;
| | - Giorgia Scarpellino
- Laboratory of General Physiology, Department of Biology and Biotechnology “L. Spallanzani”, University of Pavia, 27100 Pavia, Italy; (V.B.); (G.S.)
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3
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Ottolini M, Sonkusare SK. The Calcium Signaling Mechanisms in Arterial Smooth Muscle and Endothelial Cells. Compr Physiol 2021; 11:1831-1869. [PMID: 33792900 PMCID: PMC10388069 DOI: 10.1002/cphy.c200030] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The contractile state of resistance arteries and arterioles is a crucial determinant of blood pressure and blood flow. Physiological regulation of arterial contractility requires constant communication between endothelial and smooth muscle cells. Various Ca2+ signals and Ca2+ -sensitive targets ensure dynamic control of intercellular communications in the vascular wall. The functional effect of a Ca2+ signal on arterial contractility depends on the type of Ca2+ -sensitive target engaged by that signal. Recent studies using advanced imaging methods have identified the spatiotemporal signatures of individual Ca2+ signals that control arterial and arteriolar contractility. Broadly speaking, intracellular Ca2+ is increased by ion channels and transporters on the plasma membrane and endoplasmic reticular membrane. Physiological roles for many vascular Ca2+ signals have already been confirmed, while further investigation is needed for other Ca2+ signals. This article focuses on endothelial and smooth muscle Ca2+ signaling mechanisms in resistance arteries and arterioles. We discuss the Ca2+ entry pathways at the plasma membrane, Ca2+ release signals from the intracellular stores, the functional and physiological relevance of Ca2+ signals, and their regulatory mechanisms. Finally, we describe the contribution of abnormal endothelial and smooth muscle Ca2+ signals to the pathogenesis of vascular disorders. © 2021 American Physiological Society. Compr Physiol 11:1831-1869, 2021.
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Affiliation(s)
- Matteo Ottolini
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia, USA
| | - Swapnil K Sonkusare
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia, USA.,Department of Molecular Physiology & Biological Physics, University of Virginia, Charlottesville, Virginia, USA.,Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, Virginia, USA
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Chen YL, Baker TM, Lee F, Shui B, Lee JC, Tvrdik P, Kotlikoff MI, Sonkusare SK. Calcium Signal Profiles in Vascular Endothelium from Cdh5-GCaMP8 and Cx40-GCaMP2 Mice. J Vasc Res 2021; 58:159-171. [PMID: 33706307 PMCID: PMC8102377 DOI: 10.1159/000514210] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Accepted: 12/23/2020] [Indexed: 01/04/2023] Open
Abstract
INTRODUCTION Studies in Cx40-GCaMP2 mice, which express calcium biosensor GCaMP2 in the endothelium under connexin 40 promoter, have identified the unique properties of endothelial calcium signals. However, Cx40-GCaMP2 mouse is associated with a narrow dynamic range and lack of signal in the venous endothelium. Recent studies have proposed many GCaMPs (GCaMP5/6/7/8) with improved properties although their performance in endothelium-specific calcium studies is not known. METHODS We characterized a newly developed mouse line that constitutively expresses GCaMP8 in the endothelium under the VE-cadherin (Cdh5-GCaMP8) promoter. Calcium signals through endothelial IP3 receptors and TRP vanilloid 4 (TRPV4) ion channels were recorded in mesenteric arteries (MAs) and veins from Cdh5-GCaMP8 and Cx40-GCaMP2 mice. RESULTS Cdh5-GCaMP8 mice showed lower baseline fluorescence intensity, higher dynamic range, and higher amplitudes of individual calcium signals than Cx40-GCaMP2 mice. Importantly, Cdh5-GCaMP8 mice enabled the first recordings of discrete calcium signals in the intact venous endothelium and revealed striking differences in IP3 receptor and TRPV4 channel calcium signals between MAs and mesenteric veins. CONCLUSION Our findings suggest that Cdh5-GCaMP8 mice represent significant improvements in dynamic range, sensitivity for low-intensity signals, and the ability to record calcium signals in venous endothelium.
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Affiliation(s)
- Yen Lin Chen
- Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, Virginia, USA
| | - Thomas M Baker
- Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, Virginia, USA
| | - Frank Lee
- Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA
| | - Bo Shui
- Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA
| | - Jane C Lee
- Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA
| | - Petr Tvrdik
- Departments of Neurosurgery and Neuroscience and Bioengineering, University of Virginia, Charlottesville, Virginia, USA
| | - Michael I Kotlikoff
- Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA
| | - Swapnil K Sonkusare
- Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, Virginia, USA,
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia, USA,
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5
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Ye X, Beckett T, Bagher P, Garland CJ, Dora KA. VEGF-A inhibits agonist-mediated Ca 2+ responses and activation of IK Ca channels in mouse resistance artery endothelial cells. J Physiol 2018; 596:3553-3566. [PMID: 29862503 DOI: 10.1113/jp275793] [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] [Received: 04/19/2018] [Accepted: 05/15/2018] [Indexed: 01/06/2023] Open
Abstract
KEY POINTS Prolonged exposure to vascular endothelial growth factor A (VEGF-A) inhibits agonist-mediated endothelial cell Ca2+ release and subsequent activation of intermediate conductance Ca2+ -activated K+ (IKCa ) channels, which underpins vasodilatation as a result of endothelium-dependent hyperpolarization (EDH) in mouse resistance arteries. Signalling via mitogen-activated protein/extracellular signal-regulated kinase kinase (MEK) downstream of VEGF-A was required to attenuate endothelial cell Ca2+ responses and the EDH-vasodilatation mediated by IKCa activation. VEGF-A exposure did not modify vasodilatation as a result of the direct activation of IKCa channels, nor the pattern of expression of inositol 1,4,5-trisphosphate receptor 1 within endothelial cells of resistance arteries. These results indicate a novel role for VEGF-A in resistance arteries and suggest a new avenue for investigation into the role of VEGF-A in cardiovascular diseases. ABSTRACT Vascular endothelial growth factor A (VEGF-A) is a potent permeability and angiogenic factor that is also associated with the remodelling of the microvasculature. Elevated VEGF-A levels are linked to a significant increase in the risk of cardiovascular dysfunction, although it is unclear how VEGF-A has a detrimental, disease-related effect. Small resistance arteries are central determinants of peripheral resistance and endothelium-dependent hyperpolarization (EDH) is the predominant mechanism by which these arteries vasodilate. Using isolated, pressurized resistance arteries, we demonstrate that VEGF-A acts via VEGF receptor-2 (R2) to inhibit both endothelial cell (EC) Ca2+ release and the associated EDH vasodilatation mediated by intermediate conductance Ca2+ -activated K+ (IKCa ) channels. Importantly, VEGF-A had no direct effect against IKCa channels. Instead, the inhibition was crucially reliant on the downstream activation of the mitogen-activated protein/extracellular signal-regulated kinase kinase 1/2 (MEK1/2). The distribution of EC inositol 1,4,5-trisphosphate (IP3 ) receptor-1 (R1) was not affected by exposure to VEGF-A and we propose an inhibition of IP3 R1 through the MEK pathway, probably via ERK1/2. Inhibition of EC Ca2+ via VEGFR2 has profound implications for EDH-mediated dilatation of resistance arteries and could provide a mechanism by which elevated VEGF-A contributes towards cardiovascular dysfunction.
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Affiliation(s)
- Xi Ye
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, UK
| | - Taylor Beckett
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, UK.,School of Biomedical Sciences, University of Queensland, Brisbane, Australia
| | - Pooneh Bagher
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, UK.,Department of Medical Physiology, College of Medicine, Texas A&M University Health Science Center, Bryan, TX, USA
| | | | - Kim A Dora
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, UK
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6
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Behringer EJ. Calcium and electrical signaling in arterial endothelial tubes: New insights into cellular physiology and cardiovascular function. Microcirculation 2018; 24. [PMID: 27801542 DOI: 10.1111/micc.12328] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Accepted: 10/25/2016] [Indexed: 12/23/2022]
Abstract
The integral role of the endothelium during the coordination of blood flow throughout vascular resistance networks has been recognized for several decades now. Early examination of the distinct anatomy and physiology of the endothelium as a signaling conduit along the vascular wall has prompted development and application of an intact endothelial "tube" study model isolated from rodent skeletal muscle resistance arteries. Vasodilatory signals such as increased endothelial cell (EC) Ca2+ ([Ca2+ ]i ) and hyperpolarization take place in single ECs while shared between electrically coupled ECs through gap junctions up to distances of millimeters (≥2 mm). The small- and intermediate-conductance Ca2+ activated K+ (SKCa /IKCa or KCa 2.3/KCa 3.1) channels function at the interface of Ca2+ signaling and hyperpolarization; a bidirectional relationship whereby increases in [Ca2+ ]i activate SKCa /IKCa channels to produce hyperpolarization and vice versa. Further, the spatial domain of hyperpolarization among electrically coupled ECs can be finely tuned via incremental modulation of SKCa /IKCa channels to balance the strength of local and conducted electrical signals underlying vasomotor activity. Multifunctional properties of the voltage-insensitive SKCa /IKCa channels of resistance artery endothelium may be employed for therapy during the aging process and development of vascular disease.
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Affiliation(s)
- Erik J Behringer
- Department of Basic Sciences, Loma Linda University, Loma Linda, CA, USA
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Behringer EJ, Segal SS. Impact of Aging on Calcium Signaling and Membrane Potential in Endothelium of Resistance Arteries: A Role for Mitochondria. J Gerontol A Biol Sci Med Sci 2017; 72:1627-1637. [PMID: 28510636 DOI: 10.1093/gerona/glx079] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Accepted: 04/21/2017] [Indexed: 12/20/2022] Open
Abstract
Impaired blood flow to peripheral tissues during advanced age is associated with endothelial dysfunction and diminished bioavailability of nitric oxide (NO). However, it is unknown whether aging impacts coupling between intracellular calcium ([Ca2+]i) signaling and small- and intermediate K+ channel (SKCa/IKCa) activity during endothelium-derived hyperpolarization (EDH), a signaling pathway integral to dilation of the resistance vasculature. To address the potential impact of aging on EDH, Fura-2 photometry and intracellular recording were applied to evaluate [Ca2+]i and membrane potential of intact endothelial tubes (width, 60 µm; length, 1-3 mm) freshly isolated from superior epigastric arteries of young (4-6 mo) and old (24-26 mo) male C57BL/6 mice. In response to acetylcholine, intracellular release of Ca2+ from the endoplasmic reticulum (ER) was enhanced with aging. Further, treatment with the mitochondrial uncoupler FCCP evoked a significant increase of [Ca2+]i with membrane hyperpolarization in an SKCa/IKCa-dependent manner in the endothelium of old but not young mice. We conclude that the ability of resistance artery endothelium to release Ca2+ from intracellular stores (ie, ER and mitochondria) and hyperpolarize Vm via SKCa/IKCa activation is augmented as compensation for reduced NO bioavailability during advanced age.
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Affiliation(s)
- Erik J Behringer
- Department of Basic Sciences, Loma Linda University, California.,Department of Medical Pharmacology and Physiology, University of Missouri, Columbia
| | - Steven S Segal
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia.,Dalton Cardiovascular Research Center, Columbia, Missouri
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8
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Welsh DG, Tran CHT, Hald BO, Sancho M. The Conducted Vasomotor Response: Function, Biophysical Basis, and Pharmacological Control. Annu Rev Pharmacol Toxicol 2017; 58:391-410. [PMID: 28968190 DOI: 10.1146/annurev-pharmtox-010617-052623] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Arterial tone is coordinated among vessel segments to optimize nutrient transport and organ function. Coordinated vasomotor activity is remarkable to observe and depends on stimuli, sparsely generated in tissue, eliciting electrical responses that conduct lengthwise among electrically coupled vascular cells. The conducted response is the focus of this topical review, and in this regard, the authors highlight literature that advances an appreciation of functional significance, cellular mechanisms, and biophysical principles. Of particular note, this review stresses that conduction is enabled by a defined pattern of charge movement along the arterial wall as set by three key parameters (tissue structure, gap junctional resistivity, and ion channel activity). The impact of disease on conduction is carefully discussed, as are potential strategies to restore this key biological response and, along with it, the match of blood flow delivery with tissue energetic demand.
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Affiliation(s)
- Donald G Welsh
- Robarts Research Institute, Department of Physiology and Pharmacology, Schulich School of Medicine, University of Western Ontario, London, Ontario N6A 5B7, Canada;
| | - Cam Ha T Tran
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Bjorn O Hald
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen DK-2200, Denmark
| | - Maria Sancho
- Robarts Research Institute, Department of Physiology and Pharmacology, Schulich School of Medicine, University of Western Ontario, London, Ontario N6A 5B7, Canada;
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9
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Radu BM, Osculati AMM, Suku E, Banciu A, Tsenov G, Merigo F, Di Chio M, Banciu DD, Tognoli C, Kacer P, Giorgetti A, Radu M, Bertini G, Fabene PF. All muscarinic acetylcholine receptors (M 1-M 5) are expressed in murine brain microvascular endothelium. Sci Rep 2017; 7:5083. [PMID: 28698560 PMCID: PMC5506046 DOI: 10.1038/s41598-017-05384-z] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 05/30/2017] [Indexed: 12/25/2022] Open
Abstract
Clinical and experimental studies indicate that muscarinic acetylcholine receptors are potential pharmacological targets for the treatment of neurological diseases. Although these receptors have been described in human, bovine and rat cerebral microvascular tissue, a subtype functional characterization in mouse brain endothelium is lacking. Here, we show that all muscarinic acetylcholine receptors (M1-M5) are expressed in mouse brain microvascular endothelial cells. The mRNA expression of M2, M3, and M5 correlates with their respective protein abundance, but a mismatch exists for M1 and M4 mRNA versus protein levels. Acetylcholine activates calcium transients in brain endothelium via muscarinic, but not nicotinic, receptors. Moreover, although M1 and M3 are the most abundant receptors, only a small fraction of M1 is present in the plasma membrane and functions in ACh-induced Ca2+ signaling. Bioinformatic analyses performed on eukaryotic muscarinic receptors demonstrate a high degree of conservation of the orthosteric binding site and a great variability of the allosteric site. In line with previous studies, this result indicates muscarinic acetylcholine receptors as potential pharmacological targets in future translational studies. We argue that research on drug development should especially focus on the allosteric binding sites of the M1 and M3 receptors.
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Affiliation(s)
- Beatrice Mihaela Radu
- Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Verona, 37134, Italy.,Department of Anatomy, Animal Physiology and Biophysics, Faculty of Biology, University of Bucharest, Bucharest, 050095, Romania
| | | | - Eda Suku
- Department of Biotechnology, University of Verona, Verona, 37134, Italy
| | - Adela Banciu
- Department of Anatomy, Animal Physiology and Biophysics, Faculty of Biology, University of Bucharest, Bucharest, 050095, Romania.,Engineering Faculty, Constantin Brancusi' University, Calea Eroilor 30, Targu Jiu, 210135, Romania
| | - Grygoriy Tsenov
- Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Verona, 37134, Italy
| | - Flavia Merigo
- Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Verona, 37134, Italy
| | - Marzia Di Chio
- Department of Public Health and Community Medicine, University of Verona, Verona, 37134, Italy
| | - Daniel Dumitru Banciu
- Department of Anatomy, Animal Physiology and Biophysics, Faculty of Biology, University of Bucharest, Bucharest, 050095, Romania
| | - Cristina Tognoli
- Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Verona, 37134, Italy
| | - Petr Kacer
- National Institute of Mental Health, Klecany, 25067, Czech Republic
| | | | - Mihai Radu
- Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Verona, 37134, Italy. .,Department of Life and Environmental Physics, Horia Hulubei National Institute for Physics and Nuclear Engineering, PO Box MG-6, Reactorului 30, Magurele, 077125, Romania.
| | - Giuseppe Bertini
- Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Verona, 37134, Italy
| | - Paolo Francesco Fabene
- Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Verona, 37134, Italy
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Boerman EM, Everhart JE, Segal SS. Advanced age decreases local calcium signaling in endothelium of mouse mesenteric arteries in vivo. Am J Physiol Heart Circ Physiol 2016; 310:H1091-6. [PMID: 26945073 DOI: 10.1152/ajpheart.00038.2016] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Accepted: 02/29/2016] [Indexed: 11/22/2022]
Abstract
Aging is associated with vascular dysfunction that impairs tissue perfusion, physical activity, and the quality of life. Calcium signaling in endothelial cells (ECs) is integral to vasomotor control, exemplified by localized Ca(2+) signals within EC projections through holes in the internal elastic lamina (IEL). Within these microdomains, endothelium-derived hyperpolarization is integral to smooth muscle cell (SMC) relaxation via coupling through myoendothelial gap junctions. However, the effects of aging on local EC Ca(2+) signals (and thereby signaling between ECs and SMCs) remain unclear, and these events have not been investigated in vivo. Furthermore, it is unknown whether aging affects either the number or the size of IEL holes. In the present study, we tested the hypothesis that local EC Ca(2+) signaling is impaired with advanced age along with a reduction in IEL holes. In anesthetized mice expressing a Ca(2+)-sensitive fluorescent protein (GCaMP2) selectively in ECs, our findings illustrate that for mesenteric arteries controlling splanchnic blood flow the frequency of spontaneous local Ca(2+) signals in ECs was reduced by ∼85% in old (24-26 mo) vs. young (3-6 mo) animals. At the same time, the number (and total area) of holes per square millimeter of IEL was reduced by ∼40%. We suggest that diminished signaling between ECs and SMCs contributes to dysfunction of resistance arteries with advanced age.Listen to this article's corresponding podcast at http://ajpheart.podbean.com/e/aging-impairs-endothelial-ca2-signaling/.
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Affiliation(s)
- Erika M Boerman
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri; and
| | - Jesse E Everhart
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri; and
| | - Steven S Segal
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri; and Dalton Cardiovascular Research Center, Columbia, Missouri
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11
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Taylor MS, Francis M. Decoding dynamic Ca(2+) signaling in the vascular endothelium. Front Physiol 2014; 5:447. [PMID: 25452732 PMCID: PMC4233915 DOI: 10.3389/fphys.2014.00447] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Accepted: 10/31/2014] [Indexed: 12/15/2022] Open
Abstract
Although acute and chronic vasoregulation is inherently driven by endothelial Ca(2+), control and targeting of Ca(2+)-dependent signals are poorly understood. Recent studies have revealed localized and dynamic endothelial Ca(2+) events comprising an intricate signaling network along the vascular intima. Discrete Ca(2+) transients emerging from both internal stores and plasmalemmal cation channels couple to specific membrane K(+) channels, promoting endothelial hyperpolarization and vasodilation. The spatiotemporal tuning of these signals, rather than global Ca(2+) elevation, appear to direct endothelial functions under physiologic conditions. In fact, altered patterns of dynamic Ca(2+) signaling may underlie essential endothelial dysfunction in a variety of cardiovascular diseases. Advances in imaging approaches and analyses in recent years have allowed for detailed detection, quantification, and evaluation of Ca(2+) dynamics in intact endothelium. Here, we discuss recent insights into these signals, including their sources of origination and their functional encoding. We also address key aspects of data acquisition and interpretation, including broad applications of automated high-content analysis.
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Affiliation(s)
- Mark S Taylor
- Department of Physiology, University of South Alabama College of Medicine Mobile, AL, USA
| | - Michael Francis
- Department of Pharmacology, University of South Alabama College of Medicine Mobile, AL, USA
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12
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Mauban JRH, Zacharia J, Zhang J, Wier WG. Vascular tone and Ca(2+) signaling in murine cremaster muscle arterioles in vivo. Microcirculation 2013; 20:269-77. [PMID: 23140521 DOI: 10.1111/micc.12025] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Accepted: 11/02/2012] [Indexed: 12/12/2022]
Abstract
OBJECTIVES We sought to determine some of the molecular requirements for basal state "tone" of skeletal muscle arterioles in vivo, and whether asynchronous Ca(2+) waves are involved or not. METHODS Cremaster muscles of anesthetized exMLCK and smGCaMP2 biosensor mice were exteriorized, and the fluorescent arterioles were visualized with wide-field, confocal or multiphoton microscopy to observe Ca(2+) signaling and arteriolar diameter. RESULTS Basal state tone of the arterioles was ~50%. Local block of Ang-II receptors (AT1 ) or α1 -adrenoceptors (α1 -AR) had no effect on diameter, nor did complete block of sympathetic nerve activity (SNA). Inhibition of phospholipase C caused dilation nearly to the Ca(2+) -free (passive) diameter, as did exposure to nifedipine or 2-APB. Arterioles were also dilated when treated with SKF96365. High-resolution imaging of exMLCK fluorescence (ratio) or GCaMP2 fluorescence in smooth muscle cells failed to reveal Ca(2+) waves (although Ca(2+) waves/transients were readily detected by both biosensors in small arteries, ex vivo). CONCLUSIONS Arterioles of cremaster muscle have vascular tone of ~ 50%, which is not due to α1 -AR, AT1 R, or SNA. PLC activity, L-type Ca(2+) channels, 2-APB- and SKF96365-sensitive channels are required. Propagating Ca(2+) waves are not present. A key role for PLC and InsP3 R in vascular tone in vivo, other than producing Ca(2+) waves, is suggested.
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Affiliation(s)
- Joseph R H Mauban
- Department of Physiology, School of Medicine, University of Maryland Baltimore, Baltimore, Maryland 21201, USA
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13
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Babakinejad B, Jönsson P, López Córdoba A, Actis P, Novak P, Takahashi Y, Shevchuk A, Anand U, Anand P, Drews A, Ferrer-Montiel A, Klenerman D, Korchev YE. Local delivery of molecules from a nanopipette for quantitative receptor mapping on live cells. Anal Chem 2013; 85:9333-42. [PMID: 24004146 DOI: 10.1021/ac4021769] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Using nanopipettes to locally deliver molecules to the surface of living cells could potentially open up studies of biological processes down to the level of single molecules. However, in order to achieve precise and quantitative local delivery it is essential to be able to determine the amount and distribution of the molecules being delivered. In this work, we investigate how the size of the nanopipette, the magnitude of the applied pressure or voltage, which drives the delivery, and the distance to the underlying surface influences the number and spatial distribution of the delivered molecules. Analytical expressions describing the delivery are derived and compared with the results from finite element simulations and experiments on delivery from a 100 nm nanopipette in bulk solution and to the surface of sensory neurons. We then developed a setup for rapid and quantitative delivery to multiple subcellular areas, delivering the molecule capsaicin to stimulate opening of Transient Receptor Potential Vanilloid subfamily member 1 (TRPV1) channels, membrane receptors involved in pain sensation. Overall, precise and quantitative delivery of molecules from nanopipettes has been demonstrated, opening up many applications in biology such as locally stimulating and mapping receptors on the surface of live cells.
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Socha MJ, Domeier TL, Behringer EJ, Segal SS. Coordination of intercellular Ca(2+) signaling in endothelial cell tubes of mouse resistance arteries. Microcirculation 2013; 19:757-70. [PMID: 22860994 DOI: 10.1111/micc.12000] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2012] [Accepted: 08/01/2012] [Indexed: 12/21/2022]
Abstract
OBJECTIVE To test the hypothesis that Ca(2+) responses to GPCR activation are coordinated between neighboring ECs of resistance arteries. METHODS EC tubes were freshly isolated from superior epigastric arteries of C57BL/6 mice. Intercellular coupling was tested using microinjection of propidium iodide. Following loading with fluo-4 dye, intracellular Ca(2+) responses to ACh were imaged with confocal microscopy. RESULTS Cell-to-cell transfer of propidium iodide confirmed functional GJCs. A 1 μm ACh stimulus evoked Ca(2+) responses (9.8 ± 0.8/min, F/F(0) = 3.11 ± 0.2) which pseudo-line-scan analysis revealed as composed of Ca(2+) waves and spatially restricted Ca(2+) release events. A 100 nm ACh stimulus induced Ca(2+) responses of lower frequency (4.5 ± 0.7/min) and amplitude (F/F(0) = 1.95 ± 0.11) composed primarily of spatially restricted events. The time interval between Ca(2+) waves in adjacent cells (0.79 ± 0.12 s) was shorter (p < 0.05) than that between nonadjacent cells (1.56 ± 0.25 s). Spatially restricted Ca(2+) release events had similar frequencies and latencies between adjacent and nonadjacent cells. Inhibiting intracellular Ca(2+) release with 2-APB, Xestospongin C or thapsigargin eliminated Ca(2+) responses. CONCLUSIONS With moderate GPCR stimulation, localized Ca(2+) release events predominate among cells. Greater GPCR stimulation evokes coordinated intercellular Ca(2+) waves via the ER. Calcium signaling during GPCR activation is complex among cells, varying with stimulus intensity and proximity to actively signaling cells.
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Affiliation(s)
- Matthew J Socha
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri 65212, USA
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Westcott EB, Segal SS. Ageing alters perivascular nerve function of mouse mesenteric arteries in vivo. J Physiol 2013; 591:1251-63. [PMID: 23247111 PMCID: PMC3607869 DOI: 10.1113/jphysiol.2012.244483] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Accepted: 12/10/2012] [Indexed: 12/16/2022] Open
Abstract
Abstract Mesenteric arteries (MAs) are studied widely in vitro but little is known of their reactivity in vivo. Transgenic animals have enabled Ca(2+) signalling to be studied in isolated MAs but the reactivity of these vessels in vivo is undefined. We tested the hypothesis that ageing alters MA reactivity to perivascular nerve stimulation (PNS) and adrenoreceptor (AR) activation during blood flow control. First- (1A), second- (2A) and third-order (3A) MAs of pentobarbital-anaesthetized Young (3-6 months) and Old (24-26 months) male and female Cx40(BAC)-GCaMP2 transgenic mice (C57BL/6 background; positive or negative for the GCaMP2 transgene) were studied with intravital microscopy. A segment of jejunum was exteriorized and an MA network was superfused with physiological salt solution (pH 7.4, 37°C). Resting tone was 10% in MAs of Young and Old mice; diameters were ∼5% (1A), 20% (2A) and 40% (3A) smaller (P 0.05) in Old mice. Throughout MA networks, vasoconstriction increased with PNS frequency (1-16 Hz) but was ∼20% less in Young vs. Old mice (P 0.05) and was inhibited by tetrodotoxin (1 μm). Capsaicin (10 μm; to inhibit sensory nerves) enhanced MA constriction to PNS (P 0.05) by ∼20% in Young but not Old mice. Phenylephrine (an α1AR agonist) potency was greater in Young mice (P 0.05) with similar efficacy (∼60% constriction) across ages and MA branches. Constrictions to UK14304 (an α2AR agonist) were less (∼20%; P 0.05) and were unaffected by ageing. Irrespective of sex or transgene expression, ageing consistently reduced the sensitivity of MAs to α1AR vasoconstriction while blunting the attenuation of sympathetic vasoconstriction by sensory nerves. These findings imply substantive alterations in splanchnic blood flow control with ageing.
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Affiliation(s)
- Erika B Westcott
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO 65212, USA
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Long J, Junkin M, Wong PK, Hoying J, Deymier P. Calcium wave propagation in networks of endothelial cells: model-based theoretical and experimental study. PLoS Comput Biol 2012; 8:e1002847. [PMID: 23300426 PMCID: PMC3531288 DOI: 10.1371/journal.pcbi.1002847] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2012] [Accepted: 11/05/2012] [Indexed: 01/06/2023] Open
Abstract
In this paper, we present a combined theoretical and experimental study of the propagation of calcium signals in multicellular structures composed of human endothelial cells. We consider multicellular structures composed of a single chain of cells as well as a chain of cells with a side branch, namely a “T” structure. In the experiments, we investigate the result of applying mechano-stimulation to induce signaling in the form of calcium waves along the chain and the effect of single and dual stimulation of the multicellular structure. The experimental results provide evidence of an effect of architecture on the propagation of calcium waves. Simulations based on a model of calcium-induced calcium release and cell-to-cell diffusion through gap junctions shows that the propagation of calcium waves is dependent upon the competition between intracellular calcium regulation and architecture-dependent intercellular diffusion. Calcium wave signal has been found in a wide variety of cell types. Over the last years, a large number of calcium experiments have shown that calcium signal is not only an intracellular regulator but is also able to be transmitted to surrounding cells as intercellular signal. This paper focuses on the development of an approach with complementary integration of theoretical and experimental methods for studying the multi-level interactions in multicellular architectures and their effect on collective cell dynamic behavior. We describe new types of higher-order (across structure) behaviors arising from lower-order (within cells) phenomena, and make predictions concerning the mechanisms underlying the dynamics of multicellular biological systems. The theoretical approach describes numerically the dynamics of non-linear behavior of calcium-based signaling in model networks of cells. Microengineered, geometrically constrained networks of human umbilical vein endothelial cells (HUVEC) serve as platforms to arbitrate the theoretical predictions in terms of the effect of network topology on the spatiotemporal characteristics of emerging calcium signals.
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Affiliation(s)
- Juexuan Long
- Material Science and Engineering, University of Arizona, Tucson, Arizona, United States of America.
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Twynstra J, Ruiz DA, Murrant CL. Functional coordination of the spread of vasodilations through skeletal muscle microvasculature: implications for blood flow control. Acta Physiol (Oxf) 2012; 206:229-41. [PMID: 22726936 DOI: 10.1111/j.1748-1716.2012.02465.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2012] [Revised: 03/30/2012] [Accepted: 06/18/2012] [Indexed: 11/29/2022]
Abstract
AIM We sought to understand the integrated vascular response to muscle contraction by determining how different branch orders of the terminal microvascular network respond to stimulation using a K(ATP) channel opener pinacidil (PIN) as a muscle contraction mimetic. METHODS Using the blood perfused, hamster cremaster preparation in situ, we locally micropipette-applied 10(-5) M PIN on the capillaries, Branch arteriole (third order, two branch orders up from the capillaries) and transverse arterioles (TA) (second order, three branch orders up from the capillaries) and observed different branch orders of the microvasculature to determine where the localized vasodilation spread throughout the terminal microvascular network. RESULTS We observed that PIN stimulation of capillaries caused associated upstream vasodilation of the module inflow arteriole (MI) (fourth order, the terminal arteriole) (2.1 ± 0.4 μm), the associate Branch (1.4 ± 0.5 μm) and in the upstream direction on the TA (2.1 ± 0.5 μm). Vasodilation did not occur in all MIs (-0.2 ± 0.2 μm) from the vasodilated branch and did not go downstream on the TA (0.7 ± 0.4 μm). Branch stimulation caused upstream TA (3.3 ± 1.0 μm) and upstream Branch (1.7 ± 0.3 μm) vasodilation but not downstream TA (1.5 ± 0.6 μm) or downstream Branch (0.2 ± 0.3 μm) vasodilation. TA stimulation caused conducted responses in both directions and into all associated arteriolar Branches and MIs. CONCLUSIONS The spread of the conducted response is dependent on the vascular branch order stimulated: capillary stimulation was most specific in its direction and TA stimulation was the least specific. Our data indicate that vascular branch order is important in determining the vascular response needed to direct blood flow to contracting skeletal muscle cells.
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Affiliation(s)
- J. Twynstra
- Department of Human Health and Nutritional Science; University of Guelph; Guelph; ON; Canada
| | - D. A. Ruiz
- Department of Human Health and Nutritional Science; University of Guelph; Guelph; ON; Canada
| | - C. L. Murrant
- Department of Human Health and Nutritional Science; University of Guelph; Guelph; ON; Canada
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Taylor MS, Francis M, Qian X, Solodushko V. Dynamic Ca(2+) signal modalities in the vascular endothelium. Microcirculation 2012; 19:423-9. [PMID: 22443172 DOI: 10.1111/j.1549-8719.2012.00180.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The endothelium is vital to normal vasoregulation. Although acute vasodilation associated with broad endothelial Ca(2+) elevation is well known, the control and targeting of Ca(2+) -dependent signals in the endothelium are poorly understood. Recent studies have revealed localized IP(3) -motivated Ca(2+) events occurring basally along the intima that may provide the fundamental basis for various endothelial influences. Here, we provide an overview of dynamic endothelial Ca(2+) signals and discuss the potential role of these signals in constant endothelial control of arterial tone and the titration of functional responses in vivo. In particular, we focus on the functional architecture contributing to the properties and ultimate impact of these signals, and explore new avenues in evaluating their prevalence and specific modalities in intact tissue. Finally, we discuss spatial and temporal effector recruitment through modification of these inherent signals. It is suggested that endothelial Ca(2+) signaling is a continuum in which the specific framework of store-release components and cellular targets along the endothelium allows for differential modes of Ca(2+) signal expansion and distinctive profiles of effector recruitment. The precise composition and distribution of these inherent components may underlie dynamic endothelial control and specialized functions of different vascular beds.
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Affiliation(s)
- Mark S Taylor
- Department of Physiology, University of South Alabama College of Medicine, Mobile, Alabama 36688, USA.
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Billaud M, Lohman AW, Straub AC, Parpaite T, Johnstone SR, Isakson BE. Characterization of the thoracodorsal artery: morphology and reactivity. Microcirculation 2012; 19:360-72. [PMID: 22335567 DOI: 10.1111/j.1549-8719.2012.00172.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
OBJECTIVES In this paper, we describe the histological and contractile properties of the thoracodorsal artery (TDA), which indirectly feeds the spinotrapezius muscle. METHODS We used immunolabelling techniques to histologically characterize the TDA while the contractile properties were assessed using pressure arteriography. RESULTS Our results demonstrate that the TDA is composed of approximately one to two layers of smooth muscle cells, is highly innervated with adrenergic nerves, and develops spontaneous tone at intraluminal pressures above 80 mmHg. The reactivity of the TDA in response to various contractile agonists such as phenylephrine, noradrenaline, angiotensin II, serotonin, endothelin 1, and ATP, as well as vasodilators, shows that the TDA exhibits a remarkably comparable reactivity to what has been observed in mesenteric arteries. We further studied the different components of the TDA response to acetylcholine, and found that the TDA was sensitive to TRAM 34, a blocker of the intermediate conductance potassium channel, which is highly suggestive of an endothelium-dependent hyperpolarization. CONCLUSIONS We conclude that the TDA exhibits comparable characteristics to other current vascular models, with the additional advantage of being easily manipulated for molecular and ex vivo vasoreactivity studies.
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Affiliation(s)
- Marie Billaud
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA
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