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Masi S, Rizzoni D, Taddei S, Widmer RJ, Montezano AC, Lüscher TF, Schiffrin EL, Touyz RM, Paneni F, Lerman A, Lanza GA, Virdis A. Assessment and pathophysiology of microvascular disease: recent progress and clinical implications. Eur Heart J 2021; 42:2590-2604. [PMID: 33257973 PMCID: PMC8266605 DOI: 10.1093/eurheartj/ehaa857] [Citation(s) in RCA: 57] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 05/23/2020] [Accepted: 10/08/2020] [Indexed: 12/13/2022] Open
Abstract
The development of novel, non-invasive techniques and standardization of protocols to assess microvascular dysfunction have elucidated the key role of microvascular changes in the evolution of cardiovascular (CV) damage, and their capacity to predict an increased risk of adverse events. These technical advances parallel with the development of novel biological assays that enabled the ex vivo identification of pathways promoting microvascular dysfunction, providing novel potential treatment targets for preventing cerebral-CV disease. In this article, we provide an update of diagnostic testing strategies to detect and characterize microvascular dysfunction and suggestions on how to standardize and maximize the information obtained from each microvascular assay. We examine emerging data highlighting the significance of microvascular dysfunction in the development CV disease manifestations. Finally, we summarize the pathophysiology of microvascular dysfunction emphasizing the role of oxidative stress and its regulation by epigenetic mechanisms, which might represent potential targets for novel interventions beyond conventional approaches, representing a new frontier in CV disease reduction.
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Affiliation(s)
- Stefano Masi
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy.,Institute of Cardiovascular Science, University College London, London, UK
| | - Damiano Rizzoni
- Clinica Medica, Department of Clinical and Experimental Sciences, University of Brescia, Brescia, Italy.,Division of Medicine, Istituto Clinico Città di Brescia, Brescia, Italy
| | - Stefano Taddei
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Robert Jay Widmer
- Division of Cardiovascular Diseases, Mayo Clinic College of Medicine, Rochester, MN, USA
| | - Augusto C Montezano
- Institute of Cardiovascular & Medical Sciences, BHF Glasgow Cardiovascular Research Centre, University of Glasgow, Glasgow, UK
| | - Thomas F Lüscher
- Heart Division, Royal Brompton and Harefield Hospital and Imperial College, London, UK.,Center for Molecular Cardiology, University of Zürich, Zürich, Switzerland
| | - Ernesto L Schiffrin
- Department of Medicine and Lady Davis Institute, Sir Mortimer B. Davis-Jewish General Hospital, McGill University, Montreal, QC, Canada
| | - Rhian M Touyz
- Institute of Cardiovascular & Medical Sciences, BHF Glasgow Cardiovascular Research Centre, University of Glasgow, Glasgow, UK
| | - Francesco Paneni
- Center for Molecular Cardiology, University of Zürich, Zürich, Switzerland.,Department of Cardiology, University Heart Center, University Hospital Zurich, Zürich, Switzerland.,Department of Research and Education, University Hospital Zurich, Zürich, Switzerland
| | - Amir Lerman
- Division of Cardiovascular Diseases, Mayo Clinic College of Medicine, Rochester, MN, USA
| | - Gaetano A Lanza
- Department of Cardiovascular and Thoracic Medicine, Fondazione Policlinico Universitario A. Gemelli IRCCS, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Agostino Virdis
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
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Wenceslau CF, McCarthy CG, Earley S, England SK, Filosa JA, Goulopoulou S, Gutterman DD, Isakson BE, Kanagy NL, Martinez-Lemus LA, Sonkusare SK, Thakore P, Trask AJ, Watts SW, Webb RC. Guidelines for the measurement of vascular function and structure in isolated arteries and veins. Am J Physiol Heart Circ Physiol 2021; 321:H77-H111. [PMID: 33989082 DOI: 10.1152/ajpheart.01021.2020] [Citation(s) in RCA: 63] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The measurement of vascular function in isolated vessels has revealed important insights into the structural, functional, and biomechanical features of the normal and diseased cardiovascular system and has provided a molecular understanding of the cells that constitutes arteries and veins and their interaction. Further, this approach has allowed the discovery of vital pharmacological treatments for cardiovascular diseases. However, the expansion of the vascular physiology field has also brought new concerns over scientific rigor and reproducibility. Therefore, it is appropriate to set guidelines for the best practices of evaluating vascular function in isolated vessels. These guidelines are a comprehensive document detailing the best practices and pitfalls for the assessment of function in large and small arteries and veins. Herein, we bring together experts in the field of vascular physiology with the purpose of developing guidelines for evaluating ex vivo vascular function. By using this document, vascular physiologists will have consistency among methodological approaches, producing more reliable and reproducible results.
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Affiliation(s)
- Camilla F Wenceslau
- Department of Physiology and Pharmacology, University of Toledo College of Medicine and Life Sciences, Toledo, Ohio
| | - Cameron G McCarthy
- Department of Physiology and Pharmacology, University of Toledo College of Medicine and Life Sciences, Toledo, Ohio
| | - Scott Earley
- Department of Pharmacology, Center for Molecular and Cellular Signaling in the Cardiovascular System, Reno School of Medicine, University of Nevada, Reno, Nevada
| | - Sarah K England
- Department of Obstetrics and Gynecology, Washington University School of Medicine, St. Louis, Missouri
| | - Jessica A Filosa
- Department of Physiology, Medical College of Georgia, Augusta University, Augusta, Georgia
| | - Styliani Goulopoulou
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas
| | - David D Gutterman
- Department of Medicine, Medical College of Wisconsin Cardiovascular Center, Milwaukee, Wisconsin
| | - Brant E Isakson
- Department of Molecular Physiology and Biophysics, Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, Virginia
| | - Nancy L Kanagy
- Department of Cell Biology and Physiology, University of New Mexico, Albuquerque, New Mexico
| | - Luis A Martinez-Lemus
- Department of Medical Pharmacology and Physiology, Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
| | - Swapnil K Sonkusare
- Department of Molecular Physiology and Biophysics, Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, Virginia
| | - Pratish Thakore
- Department of Pharmacology, Center for Molecular and Cellular Signaling in the Cardiovascular System, Reno School of Medicine, University of Nevada, Reno, Nevada
| | - Aaron J Trask
- Center for Cardiovascular Research, The Heart Center, The Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio.,Department of Pediatrics, The Ohio State University College of Medicine, Columbus, Ohio
| | - Stephanie W Watts
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan
| | - R Clinton Webb
- Cardiovascular Translational Research Center, Department of Cell Biology and Anatomy, University of South Carolina, Columbia, South Carolina
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Matchkov VV, Black Joergensen H, Kamaev D, Hoegh Jensen A, Beck HC, Skryabin BV, Aalkjaer C. A paradoxical increase of force development in saphenous and tail arteries from heterozygous ANO1 knockout mice. Physiol Rep 2020; 8:e14645. [PMID: 33245843 PMCID: PMC7695021 DOI: 10.14814/phy2.14645] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 09/29/2020] [Accepted: 10/18/2020] [Indexed: 12/16/2022] Open
Abstract
A Ca2+‐activated Cl− channel protein, ANO1, is expressed in vascular smooth muscle cells where Cl− current is thought to potentiate contraction by contributing to membrane depolarization. However, there is an inconsistency between previous knockout and knockdown studies on ANO1’s role in small arteries. In this study, we assessed cardiovascular function of heterozygous mice with global deletion of exon 7 in the ANO1 gene. We found decreased expression of ANO1 in aorta, saphenous and tail arteries from heterozygous ANO1 knockout mice in comparison with wild type. Accordingly, ANO1 knockdown reduced the Ca2+‐activated Cl− current in smooth muscle cells. Consistent with conventional hypothesis, the contractility of aorta from ANO1 heterozygous mice was reduced. Surprisingly, we found an enhanced contractility of tail and saphenous arteries from ANO1 heterozygous mice when stimulated with noradrenaline, vasopressin, and K+‐induced depolarization. This difference was endothelium‐independent. The increased contractility of ANO1 downregulated small arteries was due to increased Ca2+ influx. The expression of L‐type Ca2+ channels was not affected but expression of the plasma membrane Ca2+ ATPase 1 and the Piezo1 channel was increased. Expressional analysis of tail arteries further suggested changes of ANO1 knockdown smooth muscle cells toward a pro‐contractile phenotype. We did not find any difference between genotypes in blood pressure, heart rate, pressor response, and vasorelaxation in vivo. Our findings in tail and saphenous arteries contrast with the conventional hypothesis and suggest additional roles for ANO1 as a multifunctional protein in the vascular wall that regulates Ca2+ homeostasis and smooth muscle cell phenotype.
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Affiliation(s)
- Vladimir V Matchkov
- Department of Biomedicine, MEMBRANES, Health, Aarhus University, Aarhus, Denmark
| | | | - Dmitrii Kamaev
- Department of Biomedicine, MEMBRANES, Health, Aarhus University, Aarhus, Denmark
| | - Andreas Hoegh Jensen
- Department of Biomedicine, MEMBRANES, Health, Aarhus University, Aarhus, Denmark
| | - Hans Christian Beck
- Department for Clinical Biochemistry and Pharmacology, University of Southern Denmark, Odense, Denmark
| | - Boris V Skryabin
- Medical Faculty, Core Facility Transgenic Animal and Genetic Engineering Models (TRAM), University of Muenster, Muenster, Germany
| | - Christian Aalkjaer
- Department of Biomedicine, MEMBRANES, Health, Aarhus University, Aarhus, Denmark
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Ottolini M, Daneva Z, Chen YL, Cope EL, Kasetti RB, Zode GS, Sonkusare SK. Mechanisms underlying selective coupling of endothelial Ca 2+ signals with eNOS vs. IK/SK channels in systemic and pulmonary arteries. J Physiol 2020; 598:3577-3596. [PMID: 32463112 DOI: 10.1113/jp279570] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2020] [Accepted: 05/26/2020] [Indexed: 12/21/2022] Open
Abstract
KEY POINTS Endothelial cell TRPV4 (TRPV4EC ) channels exert a dilatory effect on the resting diameter of resistance mesenteric and pulmonary arteries. Functional intermediate- and small-conductance K+ (IK and SK) channels and endothelial nitric oxide synthase (eNOS) are present in the endothelium of mesenteric and pulmonary arteries. TRPV4EC sparklets preferentially couple with IK/SK channels in mesenteric arteries and with eNOS in pulmonary arteries. TRPV4EC channels co-localize with IK/SK channels in mesenteric arteries but not in pulmonary arteries, which may explain TRPV4EC -IK/SK channel coupling in mesenteric arteries and its absence in pulmonary arteries. The presence of the nitric oxide-scavenging protein, haemoglobin α, limits TRPV4EC -eNOS signalling in mesenteric arteries. Spatial proximity of TRPV4EC channels with eNOS and the absence of haemoglobin α favour TRPV4EC -eNOS signalling in pulmonary arteries. ABSTRACT Spatially localized Ca2+ signals activate Ca2+ -sensitive intermediate- and small-conductance K+ (IK and SK) channels in some vascular beds and endothelial nitric oxide synthase (eNOS) in others. The present study aimed to uncover the signalling organization that determines selective Ca2+ signal to vasodilatory target coupling in the endothelium. Resistance-sized mesenteric arteries (MAs) and pulmonary arteries (PAs) were used as prototypes for arteries with predominantly IK/SK channel- and eNOS-dependent vasodilatation, respectively. Ca2+ influx signals through endothelial transient receptor potential vanilloid 4 (TRPV4EC ) channels played an important role in controlling the baseline diameter of both MAs and PAs. TRPV4EC channel activity was similar in MAs and PAs. However, the TRPV4 channel agonist GSK1016790A (10 nm) selectively activated IK/SK channels in MAs and eNOS in PAs, revealing preferential TRPV4EC -IK/SK channel coupling in MAs and TRPV4EC -eNOS coupling in PAs. IK/SK channels co-localized with TRPV4EC channels at myoendothelial projections (MEPs) in MAs, although they lacked the spatial proximity necessary for their activation by TRPV4EC channels in PAs. Additionally, the presence of the NO scavenging protein haemoglobin α (Hbα) within nanometer proximity to eNOS limits TRPV4EC -eNOS signalling in MAs. By contrast, co-localization of TRPV4EC channels and eNOS at MEPs, and the absence of Hbα, favour TRPV4EC -eNOS coupling in PAs. Thus, our results reveal that differential spatial organization of signalling elements determines TRPV4EC -IK/SK vs. TRPV4EC -eNOS coupling in resistance arteries.
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Affiliation(s)
- Matteo Ottolini
- Robert M. Berne Cardiovascular Research Center, University of Virginia-School of Medicine, Charlottesville, VA, USA.,Department of Pharmacology, University of Virginia-School of Medicine, Charlottesville, VA, USA
| | - Zdravka Daneva
- Robert M. Berne Cardiovascular Research Center, University of Virginia-School of Medicine, Charlottesville, VA, USA
| | - Yen-Lin Chen
- Robert M. Berne Cardiovascular Research Center, University of Virginia-School of Medicine, Charlottesville, VA, USA
| | - Eric L Cope
- Robert M. Berne Cardiovascular Research Center, University of Virginia-School of Medicine, Charlottesville, VA, USA
| | - Ramesh B Kasetti
- Department of Pharmacology and Neuroscience and the North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, TX, USA
| | - Gulab S Zode
- Department of Pharmacology and Neuroscience and the North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, TX, USA
| | - Swapnil K Sonkusare
- Robert M. Berne Cardiovascular Research Center, University of Virginia-School of Medicine, Charlottesville, VA, USA.,Department of Pharmacology, University of Virginia-School of Medicine, Charlottesville, VA, USA.,Department of Molecular Physiology and Biological Physics, University of Virginia-School of Medicine, Charlottesville, VA, USA
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5
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Jadeja RN, Thounaojam MC, Khurana S. Characterization of pressure-mediated vascular tone in resistance arteries from bile duct-ligated rats. Oncotarget. 2017;8:30706-30722. [PMID: 28430609 PMCID: PMC5458161 DOI: 10.18632/oncotarget.15409] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Accepted: 02/01/2017] [Indexed: 12/15/2022] Open
Abstract
In cirrhosis, changes in pressure-mediated vascular tone, a key determinant of systemic vascular resistance (SVR), are unknown. To address this gap in knowledge, we assessed ex vivo dynamics of pressurized mesenteric resistance arteries (diameter ~ 260 μm) from bile duct-ligated (BDL) and sham-operated (SHAM) rats and determined the underlying mechanisms. At isobaric intraluminal pressure (70 mmHg) as well as with step-wise increase in pressure (10-110 mmHg), arteries from SHAM-rats constricted more than BDL-rats, and had reduced luminal area. In both groups, incubation with LNAME (a NOS inhibitor) had no effect on pressure-mediated tone, and expression of NOS isoforms were similar. TEA, which enhances Ca2+ influx, augmented arterial tone only in SHAM-rats, with minimal effect in those from BDL-rats that was associated with reduced expression of Ca2+ channel TRPC6. In permeabilized arteries, high-dose Ca2+ and γGTP enhanced the vascular tone, which remained lower in BDL-rats that was associated with reduced ROCK2 and pMLC expression. Further, compared to SHAM-rats, in BDL-rats, arteries had reduced collagen expression which was associated with increased expression and activity of MMP-9. BDL-rats also had increased plasma reactive oxygen species (ROS). In vascular smooth muscle cells in vitro, peroxynitrite enhanced MMP-9 activity and reduced ROCK2 expression. These data provide evidence that in cirrhosis, pressure-mediated tone is reduced in resistance arteries, and suggest that circulating ROS play a role in reducing Ca2+ sensitivity and enhancing elasticity to induce arterial adaptations. These findings provide insights into mechanisms underlying attenuated SVR in cirrhosis.
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6
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Wilson C, Saunter CD, Girkin JM, McCarron JG. Clusters of specialized detector cells provide sensitive and high fidelity receptor signaling in the intact endothelium. FASEB J 2016; 30:2000-13. [PMID: 26873937 PMCID: PMC4836367 DOI: 10.1096/fj.201500090] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Accepted: 01/27/2016] [Indexed: 02/06/2023]
Abstract
Agonist-mediated signaling by the endothelium controls virtually all vascular functions. Because of the large diversity of agonists, each with varying concentrations, background noise often obscures individual cellular signals. How the endothelium distinguishes low-level fluctuations from noise and decodes and integrates physiologically relevant information remains unclear. Here, we recorded changes in intracellular Ca(2+) concentrations in response to acetylcholine in areas encompassing hundreds of endothelial cells from inside intact pressurized arteries. Individual cells responded to acetylcholine with a concentration-dependent increase in Ca(2+) signals spanning a single order of magnitude. Interestingly, however, intercellular response variation extended over 3 orders of magnitude of agonist concentration, thus crucially enhancing the collective bandwidth of endothelial responses to agonists. We also show the accuracy of this collective mode of detection is facilitated by spatially restricted clusters of comparably sensitive cells arising from heterogeneous receptor expression. Simultaneous stimulation of clusters triggered Ca(2+) signals that were transmitted to neighboring cells in a manner that scaled with agonist concentration. Thus, the endothelium detects agonists by acting as a distributed sensing system. Specialized clusters of detector cells, analogous to relay nodes in modern communication networks, integrate populationwide inputs, and enable robust noise filtering for efficient high-fidelity signaling.-Wilson, C., Saunter, C. D., Girkin, J. M., McCarron, J. G. Clusters of specialized detector cells provide sensitive and high fidelity receptor signaling in the intact endothelium.
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Affiliation(s)
- Calum Wilson
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom; and
| | - Christopher D Saunter
- Centre for Advanced Instrumentation, Biophysical Sciences Institute, Department of Physics, Durham University, Durham, United Kingdom
| | - John M Girkin
- Centre for Advanced Instrumentation, Biophysical Sciences Institute, Department of Physics, Durham University, Durham, United Kingdom
| | - John G McCarron
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom; and
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Outzen EM, Zaki M, Abdolalizadeh B, Sams A, Boonen HCM, Sheykhzade M. Translational value of mechanical and vasomotor properties of mouse isolated mesenteric resistance-sized arteries. Pharmacol Res Perspect 2015; 3:e00200. [PMID: 27022471 PMCID: PMC4777254 DOI: 10.1002/prp2.200] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 11/06/2015] [Indexed: 11/09/2022] Open
Abstract
Mice are increasingly used in vascular research for studying perturbations and responses to vasoactive agents in small artery preparations. Historically, small artery function has preferably been studied in rat isolated mesenteric resistance-sized arteries (MRA) using the wire myograph technique. Although different mouse arteries have been studied using the wire myograph no establishment of optimal settings has yet been performed. Therefore, the purposes of this study were firstly to establish the optimal settings for wire myograph studies of mouse MRA and compare them to those of rat MRA. Second, by surveying the literature, we aimed to evaluate the overall translatability of observed pharmacological vasomotor responses of mouse MRA to those obtained in rat MRA as well as corresponding and different arteries in terms of vessel size and species origin. Our results showed that the optimal conditions for maximal active force development in mouse MRA were not significantly different to those determined in rat MRA. Furthermore, we found that the observed concentration-dependent vasomotor responses of mouse MRA to noradrenaline, phenylephrine, angiotensin II, sarafotoxin 6c, 5-hydroxytryptamine, carbachol, sodium nitroprusside, and retigabine were generally similar to those described in rat MRA as well as arteries of different sizes and species origin. In summary, the results of this study provide a framework for evidence-based optimization of the isometric wire myograph setup to mouse MRA. Additionally, in terms of translational value, our study suggests that mouse MRA can be applied as a useful model for studying vascular reactivity.
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Affiliation(s)
- Emilie M Outzen
- Department of Drug Design and Pharmacology Faculty of Health and Medical Sciences University of Copenhagen Copenhagen Denmark
| | - Marina Zaki
- Department of Drug Design and Pharmacology Faculty of Health and Medical Sciences University of Copenhagen Copenhagen Denmark
| | - Bahareh Abdolalizadeh
- Department of Drug Design and Pharmacology Faculty of Health and Medical Sciences University of Copenhagen Copenhagen Denmark
| | - Anette Sams
- Department of Diabetic Complications Biology Novo Nordisk A/S Maaloev Denmark
| | - Harrie C M Boonen
- Department of Drug Design and Pharmacology Faculty of Health and Medical Sciences University of Copenhagen Copenhagen Denmark
| | - Majid Sheykhzade
- Department of Drug Design and Pharmacology Faculty of Health and Medical Sciences University of Copenhagen Copenhagen Denmark
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Jadeja RN, Rachakonda V, Bagi Z, Khurana S. Assessing Myogenic Response and Vasoactivity In Resistance Mesenteric Arteries Using Pressure Myography. J Vis Exp 2015:e50997. [PMID: 26168315 DOI: 10.3791/50997] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Small resistance arteries constrict and dilate respectively in response to increased or decreased intraluminal pressure; this phenomenon known as myogenic response is a key regulator of local blood flow. In isobaric conditions small resistance arteries develop sustained constriction known as myogenic tone (MT), which is a major determinant of systemic vascular resistance (SVR). Hence, ex vivo pressurized preparations of small resistance arteries are major tools to study microvascular function in near-physiological states. To achieve this, a freshly isolated intact segment of a small resistance artery (diameter ~260 μm) is mounted onto two small glass cannulas and pressurized. These arterial preparations retain most in vivo characteristics and permit assessment of vascular tone in real-time. Here we provide a detailed protocol for assessing vasoactivity in pressurized small resistance mesenteric arteries from rats; these arteries develop sustained vasoconstriction - approximately 25% of maximal diameter - when pressurized at 70 mmHg. These arterial preparations may be used to study the effect of investigational compounds on relationship between intra-arterial pressure and vasoactivity and determine changes in microvascular function in animal models of various diseases.
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Affiliation(s)
| | - Vikrant Rachakonda
- Division of Gastroenterology and Hepatology, University of Pittsburgh School of Medicine
| | - Zsolt Bagi
- Vascular Biology Center, Georgia Regents University
| | - Sandeep Khurana
- Section of Gastroenterology and Hepatology, Georgia Regents University;
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Abstract
Coronary blood flow closely matches to metabolic demands of heart and myocardial oxygen consumption and is conditioned by function of coronary resistance vessels. The microvascular endothelium of coronary resistance vessels is exposed to a spatially and temporally regulated input from cardiomyocytes and the haemodynamic forces of the cardiac cycle. Functional measurements of coronary pressure and flow are important approaches that provide complementary information on the function of coronary vessel function that could not be assessed by the methods utilized for the anatomic characterization of coronary disease, such as coronary angiography. The goal of this paper is to review the methodologies for assessment of coronary vascular function and haemodynamics which are utilized in research and to discuss their potential applicability in the clinical settings.
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Affiliation(s)
- Ines Drenjancevic
- Faculty of Medicine Osijek, University of Osijek, Department of Physiology and Immunology, Osijek, Croatia.
| | - Akos Koller
- Department of Physiology and Gerontology, Medical School and Szentagothai Research Centre, University of Pecs, Hungary, Department of Pathophysiology, Semmelweis University, Budapest, Hungary, Department of Physiology New York Medical College, Valhalla NY 10595, USA; Walhala University NW, USA
| | - Kristina Selthofer-Relatic
- Faculty of Medicine Osijek, University of Osijek, Dept of Internal Medicine, Osijek, Croatia; Clinical Hospital Center Osijek, Clinic for Internal Diseases, Osijek, Croatia
| | - Ivana Grizelj
- Faculty of Medicine Osijek, University of Osijek, Department of Physiology and Immunology, Osijek, Croatia
| | - Ana Cavka
- Faculty of Medicine Osijek, University of Osijek, Department of Physiology and Immunology, Osijek, Croatia
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10
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Dam VS, Boedtkjer DMB, Nyvad J, Aalkjaer C, Matchkov V. TMEM16A knockdown abrogates two different Ca(2+)-activated Cl (-) currents and contractility of smooth muscle in rat mesenteric small arteries. Pflugers Arch 2013; 466:1391-409. [PMID: 24162234 PMCID: PMC4062836 DOI: 10.1007/s00424-013-1382-1] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Revised: 10/10/2013] [Accepted: 10/10/2013] [Indexed: 12/30/2022]
Abstract
The presence of Ca2+-activated Cl− channels (CaCCs) in vascular smooth muscle cells (SMCs) is well established. Their molecular identity is, however, elusive. Two distinct Ca2+-activated Cl− currents (ICl(Ca)) were previously characterized in SMCs. We have shown that the cGMP-dependent ICl(Ca) depends on bestrophin expression, while the “classical” ICl(Ca) is not. Downregulation of bestrophins did not affect arterial contraction but inhibited the rhythmic contractions, vasomotion. In this study, we have used in vivo siRNA transfection of rat mesenteric small arteries to investigate the role of a putative CaCC, TMEM16A. Isometric force, [Ca2+]i, and SMC membrane potential were measured in isolated arterial segments. ICl(Ca) and GTPγS-induced nonselective cation current were measured in isolated SMCs. Downregulation of TMEM16A resulted in inhibition of both the cGMP-dependent ICl(Ca) and the “classical” ICl(Ca) in SMCs. TMEM16A downregulation also reduced expression of bestrophins. TMEM16A downregulation suppressed vasomotion both in vivo and in vitro. Downregulation of TMEM16A reduced agonist (noradrenaline and vasopressin) and K+-induced contractions. In accordance with the depolarizing role of CaCCs, TMEM16A downregulation suppressed agonist-induced depolarization and elevation in [Ca2+]i. Surprisingly, K+-induced depolarization was unchanged but Ca2+ entry was reduced. We suggested that this is due to reduced expression of the L-type Ca2+ channels, as observed at the mRNA level. Thus, the importance of TMEM16A for contraction is, at least in part, independent from membrane potential. This study demonstrates the significance of TMEM16A for two SMCs ICl(Ca) and vascular function and suggests an interaction between TMEM16A and L-type Ca2+ channels.
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Affiliation(s)
- Vibeke Secher Dam
- Department of Biomedicine, MEMBRANES, Aarhus University, Ole Worms Alle bygn.4, 1163, Aarhus, C 8000, Denmark
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11
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Seker F, Hesser J, Neumaier-Probst E, Groden C, Brockmann MA, Schubert R, Brockmann C. Dose-response relationship of locally applied nimodipine in an ex vivo model of cerebral vasospasm. Neuroradiology 2012; 55:71-6. [PMID: 22864556 DOI: 10.1007/s00234-012-1079-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Accepted: 07/23/2012] [Indexed: 11/25/2022]
Abstract
INTRODUCTION Cerebral vasospasm is a severe complication of subarachnoid hemorrhage (SAH). The calcium channel inhibitor nimodipine has been used for treatment of cerebral vasospasm. No evidence-based recommendations for local nimodipine administration at the site of vasospasm exist. The purpose of this study was to quantify nimodipine's local vasodilatory effect in an ex vivo model of SAH-induced vasospasm. METHODS SAH-induced vasospasm was modeled by contracting isolated segments of rat superior cerebellar arteries with a combination of serotonin and a synthetic analog of prostaglandin A(2). A pressure myograph system was used to determine vessel reactivity of spastic as well as non-spastic arteries. RESULTS Compared to the initial vessel diameter, a combination of serotonin and prostaglandin induced considerable vasospasm (55 ± 2.5 % contraction; n = 12; p < 0.001). Locally applied nimodipine dilated the arteries in a concentration-dependent manner starting at concentrations as low as 1 nM (n = 12; p < 0.05). Concentrations higher than 100 nM did not relevantly increase the vasodilatory effect. Nimodipine's vasodilatory effect was smaller in spastic than in non-spastic vessels (n = 12; p < 0.05), which we assume to be due to structural changes in the vessel wall. CONCLUSION The described ex vivo model allows to investigate the dose-dependent efficacy of spasmolytic drugs prior to in vivo experiments. Low concentrations of locally applied nimodipine have a strong vasodilatory effect, which is of relevance when considering the local application of nimodipine in cerebral vasospasm.
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Affiliation(s)
- Fatih Seker
- Experimental Radiation Oncology, University Medical Center Mannheim, Mannheim, Germany
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12
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Abstract
Endothelial dysfunction precedes the development of morphological atherosclerotic changes and can also contribute to lesion development in cardiovascular diseases. Currently, there is a lack of a single method to determine endothelial function of the entire range of vessel dimensions from aorta to arterioles. Here we assessed endothelial function of a large range of size arteries using a unified isovolumic myograph method. The method maintains a constant volume of fluid in the lumen of the vessel during contraction and relaxation, which are characterized by an increase and a decrease of pressure, respectively. Segments of six aortas, six common femoral arteries, and six mesenteric arteries from rats; six carotid arteries from mice; and six coronary and carotid arteries from pigs were used. The endothelium-dependent dose-response vasorelaxation was determined with endothelium-dependent vasodilators while arterial preconstriction was induced with vasoconstrictors at a submaximal dose. The circumferential midtension during vascular reactivity varied from 43.1 ± 7.9 to 2.59 ± 0.46 mN/mm (from large to small arteries), whereas the circumferential midstress showed a much smaller variation from 217 ± 23.5 to 123 ± 15.3 kPa (in the same range of vessels). We also found that overinflation and axial overelongation compromised endothelium-dependent vasorelaxation to underscore the significance of vessel preload. In conclusion, an isovolumic myograph was used to unify arterial vasoreactivity from large to small arteries and shows the uniformity of wall stress and %tension throughout the range of vessel sizes.
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Affiliation(s)
- Xiao Lu
- Department of Biomedical Engineering, Indiana University Purdue University Indianapolis, Indianapolis, Indiana 46202, USA
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13
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14
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Charles SM, Zhang L, Longo LD, Buchholz JN, Pearce WJ. Postnatal maturation attenuates pressure-evoked myogenic tone and stretch-induced increases in Ca2+ in rat cerebral arteries. Am J Physiol Regul Integr Comp Physiol 2007; 293:R737-44. [PMID: 17553845 DOI: 10.1152/ajpregu.00869.2006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Although postnatal maturation potently modulates agonist-induced cerebrovascular contractility, its effects on the mechanisms mediating cerebrovascular myogenic tone remain poorly understood. Because the regulation of calcium influx and myofilament calcium sensitivity change markedly during early postnatal life, the present study tested the general hypothesis that early postnatal maturation increases the pressure sensitivity of cerebrovascular myogenic tone via age-dependent enhancement of pressure-induced calcium mobilization and myofilament calcium sensitivity. Pressure-induced myogenic tone and changes in artery wall intracellular calcium concentrations ([Ca(2+)](i)) were measured simultaneously in endothelium-denuded, fura-2-loaded middle cerebral arteries (MCA) from pup [postnatal day 14 (P14)] and adult (6-mo-old) Sprague-Dawley rats. Increases in pressure from 20 to 80 mmHg enhanced myogenic tone in MCA from both pups and adults although the normalized magnitudes of these increases were significantly greater in pup than adult MCA. At each pressure step, vascular wall [Ca(2+)](i) was also significantly greater in pup than in adult MCA. Nifedipine significantly attenuated pressure-evoked constrictions in pup MCA and essentially eliminated all responses to pressure in the adult MCA. Both pup and adult MCA exhibited pressure-dependent increases in calcium sensitivity, as estimated by changes in the ratio of pressure-induced myogenic tone to wall [Ca(2+)](i). However, there were no differences in the magnitudes of these increases between pup and adult MCA. The results support the view that regardless of postnatal age, changes in both calcium influx and myofilament calcium sensitivity contribute to the regulation of cerebral artery myogenic tone. The greater cerebral myogenic response in P14 compared with adult MCA appears to be due to greater pressure-induced increases in [Ca(2+)](i), rather than enhanced augmentation of myofilament calcium sensitivity.
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Affiliation(s)
- Shelton M Charles
- Department of Physiology and Pharmacology, Center for Perinaltal Biology, Loma Linda University, School of Medicine, Loma Linda, CA 92350, USA
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15
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Shaw L, O'Neill S, Jones CJP, Austin C, Taggart MJ. Comparison of U46619-, endothelin-1- or phenylephrine-induced changes in cellular Ca2+ profiles and Ca2+ sensitisation of constriction of pressurised rat resistance arteries. Br J Pharmacol 2004; 141:678-88. [PMID: 14744813 PMCID: PMC1574231 DOI: 10.1038/sj.bjp.0705647] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
1. In pressurised rat mesenteric small arteries (50 mmHg), we examined the effects of stimulation with U46619, endothelin-1 (ET-1) or phenylephrine (PE) on changes in vessel diameter, global [Ca(2+)](i), individual smooth muscle cell [Ca(2+)](i) and Ca(2+)-sensitisation of contraction. 2. U46619 or ET-1 gave tonic diameter reductions, whereas PE-stimulated vessels gave tonic contractions or initial vasoconstrictions followed by diameter oscillations. Global [Ca(2+)](i) changes were transient for each agonist, with tonic constrictions being accompanied by maintained submaximal global [Ca(2+)](i) levels. 3. U46619, ET-1 or PE tonic constrictions were accompanied by apparently asynchronous [Ca(2+)](i) waves in individual smooth muscle cells of the vessel wall, as examined by confocal fluorescent microscopy. In vessels exhibiting vasomotion to PE, some apparent synchrony of activation of individual cells was evident; however, this was incomplete with many cells responding out of phase with their neighbours. 4. In alpha-toxin-permeabilised preparations, agonist-induced Ca(2+)-sensitisation of constriction at submaximal Ca(2+) (pCa6.7) in the presence of GTP was greater with U46619 or ET than PE. 5. We conclude that, in pressurised mesenteric arteries, (i) a general feature of receptor-coupled constriction is the generation of periodic smooth muscle [Ca(2+)](i) waves; (ii) complete synchrony of Ca(2+) oscillations between smooth muscle cells is not a prerequisite for receptor-coupled vasomotion; (iii) varied Ca(2+)-sensitising actions of agonists may partly determine tonic or phasic vessel responses to different stimuli.
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Affiliation(s)
- Linda Shaw
- Smooth Muscle Physiology Group, Cardiovascular Research, University of Manchester, Manchester
| | - Stephen O'Neill
- Unit of Cardiac Physiology, Cardiovascular Research, University of Manchester, Manchester
| | - Carolyn J P Jones
- Maternal and Fetal Health Research Centre, University of Manchester, Manchester
| | - Clare Austin
- Smooth Muscle Physiology Group, Cardiovascular Research, University of Manchester, Manchester
| | - Michael J Taggart
- Smooth Muscle Physiology Group, Cardiovascular Research, University of Manchester, Manchester
- Maternal and Fetal Health Research Centre, University of Manchester, Manchester
- Author for correspondence:
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16
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Abstract
A high salt diet in some species results in elevated arterial blood pressure and alterations in vascular smooth muscle responses to agonists. Weanling male Sprague-Dawley rats were given either a high salt diet containing 8 % or a low salt diet of 0.4 % sodium chloride for a period of 4 weeks. At the end of the feeding period, tail systolic pressure was higher in the high salt than in low salt rats. The rats were then killed and the intestines removed. Vascular smooth muscle (VSM) responses were estimated from the changes in lumenal diameter of pressurised second order mesenteric resistance arteries. High salt diet resulted in enhanced VSM responses to noradrenaline. The vessels dilated in response both to acetylcholine and to sodium nitroprusside and the responses were similar in vessels from both high and low salt rats. However, vessels from high salt rats were resistant to the blocking of endothelium derived nitric oxide (EDNO) with L-NAME and the responses were instead abolished by blocking endothelium derived hyperpolarising factor (EDHF) with apamin and charybdotoxin. These results show that in Sprague-Dawley rats, a high salt diet enhances the vasoconstriction in response to noradrenaline. The vasodilatory responses to acetylcholine were not significantly changed. However, they appeared to be mediated mainly by EDHF rather than by EDNO as in the low salt animals.
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Affiliation(s)
- O A Sofola
- Institute for Cardiovascular Research, University of Leeds, Leeds LS2 9JT, UK
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17
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Gandley RE, Conrad KP, McLaughlin MK. Endothelin and nitric oxide mediate reduced myogenic reactivity of small renal arteries from pregnant rats. Am J Physiol Regul Integr Comp Physiol 2001; 280:R1-7. [PMID: 11124127 DOI: 10.1152/ajpregu.2001.280.1.r1] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We tested the hypothesis that endothelin acting through the endothelial ET(B) receptor subtype and the nitric oxide (NO) pathway accounts for reduced myogenic reactivity of the renal resistance vasculature during pregnancy. Small renal arteries (100-200 microm) were isolated from virgin and midterm pregnant rats when gestational renal hyperfiltration and vasodilation are maximal in this species. Myogenic reactivity (the adjustment of arterial diameter in response to a change in transmural pressure) was assessed with a pressurized myograph system. A rapid increase in transmural pressure from 60 to 80 mmHg resulted in a 2.4% diameter increase in vessels from virgin compared with an 8.1% increase in arteries from midgestation rats (n = 8 each, P < 0.05). Thus myogenic reactivity is markedly reduced during pregnancy. Incubation with the NO synthase inhibitors, an ET(B) receptor subtype antagonist (RES-701-1), the nonselective ET(A/B) receptor blocker (SB-209670), or endothelial removal abrogated the reduced myogenic reactivity of vessels from gravid rats without affecting myogenic reactivity in arteries from virgin animals. Thus the endothelium mediates the reduced myogenic reactivity of small renal arteries of midgestation rats most likely through the ET(B) receptor subtype and NO pathway.
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Affiliation(s)
- R E Gandley
- Department of Obstetrics, Gynecology and Reproductive Sciences, University of Pittsburgh and Magee-Womens Research Institute, Pittsburgh, Pennsylvania 15213, USA. gandleyr+@pitt.edu
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18
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Abstract
Coronary blood flow in the subendocardium is preferentially increased by adenosine but is redistributed to the subepicardium during ischemia in association with coronary pressure reduction. The mechanism for this flow redistribution remains unclear. Since adenosine is released during ischemia, it is possible that the coronary microcirculation exhibits a transmural difference in vasomotor responsiveness to adenosine at various intraluminal pressures. Although the ATP-sensitive K(+) (K(ATP)) channel has been shown to be involved in coronary arteriolar dilation to adenosine, its role in the transmural adenosine response remains elusive. To address these issues, pig subepicardial and subendocardial arterioles (60-120 micrometer) were isolated, cannulated, and pressurized to 20, 40, 60, or 80 cmH(2)O without flow for in vitro study. At each of these pressures, vessels developed basal tone and dilated concentration dependently to adenosine and the K(ATP) channel opener pinacidil. Subepicardial and subendocardial arterioles dilated equally to adenosine and pinacidil at 60 and 80 cmH(2)O luminal pressure. At lower luminal pressures (i.e., 20 and 40 cmH(2)O), vasodilation in both vessel types was enhanced. Enhanced vasodilatory responses were not affected by removal of endothelium but were abolished by the K(ATP) channel inhibitor glibenclamide. In a manner similar to reducing pressure, a subthreshold dose of pinacidil potentiated vasodilation to adenosine. In contrast to adenosine, dilation of coronary arterioles to sodium nitroprusside was independent of pressure changes. These results indicate that coronary microvascular dilation to adenosine is enhanced at lower intraluminal pressures by selective activation of smooth muscle K(ATP) channels. Since microvascular pressure has been shown to be consistently lower in the subendocardium than in the subepicardium, it is likely that the inherent pressure gradient in the coronary microcirculation across the ventricular wall may be an important determinant of transmural flow in vivo during resting conditions or under metabolic stress with adenosine release.
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Affiliation(s)
- C Zhang
- Department of Medical Physiology, Cardiovascular Research Institute, The Texas A&M University System Health Science Center, College Station, Texas 77843-1114, USA
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19
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Abstract
1. The influence of 17 beta-oestradiol on pressurized isolated rat mesenteric and coronary small arteries was investigated. 2. 17 beta-oestradiol caused rapid (t1.0 < 5 mins) concentration-dependent relaxations of pre-contracted pressurized (50 mmHg) isolated rat mesenteric and coronary arteries. Similar responses were observed in both vessel types. Significant relaxations were only observed at concentrations exceeding 3 microM. 3. The vasodilatory responses in both types of artery were unaffected by 10 microM L-nitro arginine (L-NNA) alone or in the presence of 10 microM indomethacin, inhibitors of nitric oxide and prostaglandin synthesis respectively. They were also unaffected by the pre-contracting agent used i.e. high K+ or U46619 (a thromboxane analogue). 4. Neither the oestrogen receptor antagonist ICI 182,780 (10 microM) nor the protein synthesis inhibitor cycloheximide (100 microM) had any effect on the responses of mesenteric arteries to 17 beta-oestradiol. 5. 17 alpha-oestradiol had only a minor effect on mesenteric arterial diameter over a concentration range similar to the effective vasodilatory range for 17 beta-oestradiol. 6. Membrane impermeant 17 beta-oestradiol conjugated to bovine serum albumin (beta-oestradiol-17-hemisuccinate-BSA) (E-H-BSA) resulted in a vasodilatation of pressurized arteries. 7. Wortmannin, an inhibitor of myosin light chain kinase, near maximally relaxed pressurized mesenteric arteries although the time course for the response was significantly slower than that for 17 beta-oestradiol. 8. These results taken together suggest that the acute effects of 17 beta-oestradiol on isolated pressurized arterial tone may be due to effects directly on the vascular smooth muscle via non-genomic mechanisms that involve a stereospecific interaction at the plasma membrane.
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Affiliation(s)
- L Shaw
- University Department of Medicine, Manchester Royal Infirmary
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20
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Tankó LB, Mikkelsen EO, Simonsen U. A new experimental approach in endothelium-dependent pharmacological investigations on isolated porcine coronary arteries mounted for impedance planimetry. Br J Pharmacol 1999; 128:165-73. [PMID: 10498848 PMCID: PMC1571598 DOI: 10.1038/sj.bjp.0702752] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1. The aim of this study was to investigate whether the balloon-based impedance planimetry technique could be a useful tool in endothelium-dependent investigations. 2. Porcine large coronary arteries contracted with prostaglandin F2alpha (PGF2alpha, 10 microM) did not relax to bradykinin (0.1 nM - 0.1 microM), but did relax to sodium nitroprusside (SNP, 10 microM). However, after eversion of the segments, bradykinin induced relaxations with pD2 values and maximal responses of 8.78+/-0.09 and 75+/-2% (n=6), respectively. 3. Incubation with captopril (1 microM) did not reveal a relaxation to bradykinin in the normal vessel configuration and had no influence on the concentration-relaxation relationship in everted segments. 4. Lowering the luminal pressure in contracted segments from 131+/-5 mmHg (isometric, n=5) to 60 mmHg (isobaric, n=5) did not facilitate the action of bradykinin. 5. Eversion of segments did not influence the concentration-response relationship for K+ (4.7 - 125 mM), PGF2alpha (0.3 - 30 microM), and SNP (30 nM - 30 microM), although the time-courses of responses were faster when the agents were added from the intimal compared to the adventitial side of the preparation. 6. In the same everted segment contracted with PGF2alpha, the concentration-response relationship for bradykinin was not different under isometric and isobaric conditions. 7. These results indicate that, (1) reduced endothelium-dependent relaxations to adventitially administered substances can be ascribed to a diffusion barrier in the vessel wall, while enzymatic degradation, luminal pressure and precontractile responses seem not to play a role, (2) impedance planimetry applied to everted cylindrical segments could be a useful experimental approach in pharmacological studies of endothelium-dependent responses under isobaric and isometric conditions.
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Affiliation(s)
- L B Tankó
- Department of Pharmacology, University of Aarhus, The Bartholin Building, DK-8000 Aarhus C, Denmark.
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21
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Touyz RM, Endemann D, He G, Li JS, Schiffrin EL. Role of AT2 receptors in angiotensin II-stimulated contraction of small mesenteric arteries in young SHR. Hypertension 1999; 33:366-72. [PMID: 9931131 DOI: 10.1161/01.hyp.33.1.366] [Citation(s) in RCA: 107] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
This study assesses the receptor subtype (AT1 and AT2) through which angiotensin II (Ang II) mediates contraction in small arteries of young and adult spontaneously hypertensive rats (SHR). Segments of third-order mesenteric arteries ( approximately 200 microm in lumen diameter) were mounted in a pressurized system. Systolic blood pressure and media:lumen ratio of small arteries were significantly greater (P<0.001) in young SHR and adult SHR than in age-matched Wistar-Kyoto rats (WKY). Ang II-induced contractile effects were significantly increased (P<0.05) in young SHR compared with age-matched WKY. AT1 blockade with losartan, and combined AT1 and AT2 blockade with losartan and PD123319, abolished Ang II-stimulated contraction in young and adult rats. AT2 blockade (PD123319) significantly reduced (P<0.01) Ang II-elicited contraction in young SHR but had no effect in WKY or adult SHR, indicating that AT2 receptors may contribute to Ang II-induced contraction in young SHR. To determine the Ang receptor status in rat mesenteric vessels, AT1 and AT2 receptor mRNA expression was determined by reverse transcription-polymerase chain reaction. AT1 and AT2 receptor protein expression were detected by Western blot analysis. AT1 receptor mRNA was equally expressed in age-matched rats, but expression was significantly lower in young rats compared with adult rats. AT2 receptor mRNA was weakly expressed in WKY and adult SHR. In vessels from young SHR, AT2 receptor mRNA expression was significantly increased compared with the other groups. AT1 receptor protein was equally expressed in adult rats of both strains but was undetectable in young rats. AT2 receptor protein was only detectable in young rats, with the magnitude of expression greater in SHR than WKY. In conclusion, Ang II-stimulated contractile responses are augmented in vessels from young SHR. These effects are reduced by selective AT2 blockade and abolished by AT1 blockade, indicating that both Ang receptor subtypes are involved in contraction in young SHR. In WKY and adult SHR, losartan, but not PD123319, inhibited Ang II-induced contraction, indicating the exclusive involvement of AT1 receptors. Thus, in SHR, in the phase of developing hypertension, enhanced Ang II-stimulated vascular contraction may be associated with changes in Ang II receptor status, as evidenced pharmacologically and by increased vascular AT2 receptor mRNA and protein expression.
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MESH Headings
- Aging/physiology
- Angiotensin II/pharmacology
- Angiotensin Receptor Antagonists
- Animals
- Blood Pressure
- Hypertension/physiopathology
- Imidazoles/pharmacology
- In Vitro Techniques
- Losartan/pharmacology
- Mesenteric Artery, Superior/drug effects
- Mesenteric Artery, Superior/physiology
- Mesenteric Artery, Superior/physiopathology
- Muscle Contraction/drug effects
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/physiology
- Muscle, Smooth, Vascular/physiopathology
- Pyridines/pharmacology
- Rats
- Rats, Inbred SHR
- Rats, Inbred WKY
- Receptor, Angiotensin, Type 1
- Receptor, Angiotensin, Type 2
- Receptors, Angiotensin/physiology
- Vasoconstriction/drug effects
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Affiliation(s)
- R M Touyz
- Medical Research Council Multidisciplinary Research Group on Hypertension, Clinical Research Institute of Montreal and Université de Montréal, Montreal, Quebec,
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Fenger-Gron J, Mulvany MJ, Christensen KL. Intestinal blood flow is controlled by both feed arteries and microcirculatory resistance vessels in freely moving rats. J Physiol 1997; 498 ( Pt 1):215-24. [PMID: 9023779 PMCID: PMC1159245 DOI: 10.1113/jphysiol.1997.sp021852] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
1. In freely moving rats, intestinal blood flow, aortic blood pressure and blood pressure at the base of mesenteric arcades were measured simultaneously so as to determine the role of feed arteries and of the microcirculation in the control of intestinal vascular resistance. Segmental resistances of feed arteries (Rfeed) and of microcirculatory vessels (Rmicro) were calculated. 2. At rest, Rfeed and Rmicro were 32 and 68%, respectively, of the total intestinal vascular resistance. 3. Injection of noradrenaline (2 micrograms i.v,) increased Rfeed by 151% and Rmicro by 243%. Angiotensin II (400 ng i.v.) did not increase Rfeed significantly, but increased Rmicro by 239%. Conversely, serotonin (15 micrograms i.v.) increased Rfeed by 414% but did not affect Rmicro significantly. 4. Spontaneous physical activity increased Rfeed by 29% and Rmicro by 39%, while sudden environmental stress increased Rfeed by 116% and Rmicro by 129%. Infused noradrenaline (1 microgram min-1 i.v.) or adrenaline (0.8 microgram min-1 i.v.) reduced intestinal flow by 21 and 16% respectively, while noradrenaline, but not adrenaline, increased intestinal resistances. 5. alpha 1-Blockade with prazosin (0.1 mg i.v.) reduced Rfeed and Rmicro by 43 and 16%, respectively. Thereafter, environmental stress decreased Rfeed by 24% while Rmicro was unaffected. Intravenous noradrenaline and adrenaline responses were attenuated. 6. We conclude that in freely moving rats, mesenteric feed arteries, as well as microcirculatory vessels, are true resistance vessels, and that both participate in the control of intestinal blood flow.
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Affiliation(s)
- J Fenger-Gron
- Department of Pharmacology, University of Aarhus, Denmark
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