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Lu C, Zhang L, Chen X, Wan H, Dong H. Cl - induces endothelium-dependent mesenteric arteriolar vasorelaxation through the NKCC1/TRPV4/NCX axis. Life Sci 2023; 330:121942. [PMID: 37451399 DOI: 10.1016/j.lfs.2023.121942] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Revised: 07/10/2023] [Accepted: 07/11/2023] [Indexed: 07/18/2023]
Abstract
AIMS Although absorbed NaCl increases intestinal blood flow to facilitate absorption and transportation, it is unclear if it can directly mediate mesenteric arterial relaxation. We aimed to investigate and test our hypothesis that Cl- induces mesenteric arterial vasorelaxation via endothelium-dependent hyperpolarization (EDH). MAIN METHODS We used wire myograph to study NaCl-induced vasorelaxation of mesenteric arteries isolated from mice. Cl-, Ca2+ and K+ imaging was performed in human vascular endothelial cells pre-treated with pharmacological agents. KEY FINDINGS The Cl- concentration-dependently induced vasorelaxation of mesenteric arteries likely through EDH. The Cl--induced vasorelaxation was attenuated in TRPV4 KO mice and inhibited by selective blockers of Na+-K+-2Cl- cotransporter 1 (NKCC1) (bumetanide, 10 μM), transient receptor potential vanilloid 4 (TRPV4) (RN-1734, 40 μM), and small conductance Ca2+-activated K+ channels (SKCa) (apamin, 3 μM)/ intermediate conductance Ca2+-activated K+ channels (IKCa) (TRAM-34, 10 μM) and myoendothelial gap junction (18α-glycyrrhetinic acid, 10 μM), but enhanced by a selective activator of IKCa/SKCa (SKA-31, 0.3 μM). Cl- decreased intracellular K+ concentrations in endothelial cells, which was reversed by apamin (200 nM) plus TRAM-34 (500 nM). Extracellular Cl- raised intracellular Cl- concentrations in endothelial cells, which was attenuated by bumetanide (10 μM). Finally, Cl- induced a transient Ca2+ signaling via TRPV4 in endothelial cells, which became sustained when the Ca2+ exit mode of Na+-Ca2+ exchanger (NCX) was blocked. SIGNIFICANCE Cl- induces a pure EDH-mediated vasorelaxation of mesenteric arteries through activation of endothelial NKCC1/TRPV4/NCX axis. We have provided a novel insight into the role of Cl--induced vasorelaxation via EDH mechanism.
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Affiliation(s)
- Cheng Lu
- Department of Pharmacology, School of Pharmacy, Qingdao University Medical College, #1 Ningde Road, Qingdao 266073, China; Department of Gastroenterology, Xinqiao Hospital, Army Medical University, Chongqing 400037, China
| | - Luyun Zhang
- Department of Pediatric Intensive Care Unit, Children's Hospital of Chongqing Medical University, Chongqing 400014, China
| | - Xiongying Chen
- Department of Pediatric Intensive Care Unit, Children's Hospital of Chongqing Medical University, Chongqing 400014, China
| | - Hanxing Wan
- Department of Gastroenterology, Xinqiao Hospital, Army Medical University, Chongqing 400037, China.
| | - Hui Dong
- Department of Pharmacology, School of Pharmacy, Qingdao University Medical College, #1 Ningde Road, Qingdao 266073, China; Department of Gastroenterology, Xinqiao Hospital, Army Medical University, Chongqing 400037, China.
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2
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Yang W, Li Q, Duncan JW, Bakrania BA, Bradshaw JL, Granger JP, Rana S, Spradley FT. Luteolin-induced vasorelaxation in uterine arteries from normal pregnant rats. Pregnancy Hypertens 2020; 23:11-17. [PMID: 33161224 DOI: 10.1016/j.preghy.2020.10.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 10/15/2020] [Accepted: 10/16/2020] [Indexed: 12/20/2022]
Abstract
BACKGROUND The flavonoid, luteolin, promotes vasorelaxation in various arteries through endothelial-dependent and independent mechanisms. Although there is growing interest in the vasoactive effects of flavonoids on maternal vascular function during pregnancy, it is unknown whether luteolin elicits vasorelaxation in the uterine circulation. We tested the hypothesis that luteolin induces vasorelaxation via endothelial-dependent mechanisms in uterine arteries from normal pregnant rats during late gestation. METHODS Uterine arteries and aortas were isolated from Sprague-Dawley rats at gestational day 19 and prepared for wire myography. RESULTS The potency of luteolin-induced vasorelaxation was examined between uterine arteries and the aortas. By 50 µM of luteolin, there was complete relaxation (100.5 ± 5.2%) in uterine arteries as compared to aortas (27.5 ± 10.0%). Even the highest concentration of 100 µM luteolin produced less than half relaxation (43.6 ± 8.6%) in aortas compared to uterine arteries. We then explored if luteolin-induced vasorelaxation in uterine arteries from pregnant rats was mediated by endothelial-dependent vasorelaxation pathways, including nitric oxide synthase (NOS), cyclooxygenase (COX), or potassium (K+) channels. Blocking these pathways with N(G)-Nitro-l-arginine methyl ester hydrochloride (L-NAME), indomethacin, or tetraethylammonium (TEA)/high potassium chloride (KCl), respectively, did not alter luteolin responses in uterine arteries from pregnant rats. These findings suggested that endothelial factors may not mediate luteolin-induced vasorelaxation in uterine arteries during pregnancy. Indeed, experiments where the endothelium was removed did not alter luteolin-induced vasorelaxation in uterine arteries during pregnancy. CONCLUSIONS Luteolin directly promotes vasorelaxation in the medial smooth muscle layer of uterine arteries during normal pregnancy.
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Affiliation(s)
- Weiwei Yang
- School of Biosciences, Weifang Medical University, Weifang 261053, China; Department of Physiology and Biophysics, The University of Mississippi Medical Center, Jackson, MS 39216, United States
| | - Qinghua Li
- School of Public Health and Management, Weifang Medical University, Weifang 261053, China; Department of Physiology and Biophysics, The University of Mississippi Medical Center, Jackson, MS 39216, United States
| | - Jeremy W Duncan
- Department of Physiology and Biophysics, The University of Mississippi Medical Center, Jackson, MS 39216, United States
| | - Bhavisha A Bakrania
- Department of Physiology and Biophysics, The University of Mississippi Medical Center, Jackson, MS 39216, United States
| | - Jessica L Bradshaw
- Department of Physiology and Biophysics, The University of Mississippi Medical Center, Jackson, MS 39216, United States
| | - Joey P Granger
- Department of Physiology and Biophysics, The University of Mississippi Medical Center, Jackson, MS 39216, United States
| | - Sarosh Rana
- Department of Obstetrics and Gynecology, The University of Chicago, Chicago, IL 60637, United States.
| | - Frank T Spradley
- Department of Physiology and Biophysics, The University of Mississippi Medical Center, Jackson, MS 39216, United States; Department of Surgery, The University of Mississippi Medical Center, Jackson, MS 39216, United States
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Triggle CR, Ding H, Marei I, Anderson TJ, Hollenberg MD. Why the endothelium? The endothelium as a target to reduce diabetes-associated vascular disease. Can J Physiol Pharmacol 2020; 98:415-430. [PMID: 32150686 DOI: 10.1139/cjpp-2019-0677] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Over the past 66 years, our knowledge of the role of the endothelium in the regulation of cardiovascular function and dysfunction has advanced from the assumption that it is a single layer of cells that serves as a barrier between the blood stream and vascular smooth muscle to an understanding of its role as an essential endocrine-like organ. In terms of historical contributions, we pay particular credit to (1) the Canadian scientist Dr. Rudolf Altschul who, based on pathological changes in the appearance of the endothelium, advanced the argument in 1954 that "one is only as old as one's endothelium" and (2) the American scientist Dr. Robert Furchgott, a 1998 Nobel Prize winner in Physiology or Medicine, who identified the importance of the endothelium in the regulation of blood flow. This review provides a brief history of how our knowledge of endothelial function has advanced and now recognize that the endothelium produces a plethora of signaling molecules possessing paracrine, autocrine, and, arguably, systemic hormone functions. In addition, the endothelium is a therapeutic target for the anti-diabetic drugs metformin, glucagon-like peptide I (GLP-1) receptor agonists, and inhibitors of the sodium-glucose cotransporter 2 (SGLT2) that offset the vascular disease associated with diabetes.
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Affiliation(s)
- Chris R Triggle
- Departments of Pharmacology and Medical Education, Weill Cornell Medical College, Doha, Qatar
| | - Hong Ding
- Departments of Pharmacology and Medical Education, Weill Cornell Medical College, Doha, Qatar
| | - Isra Marei
- Departments of Pharmacology and Medical Education, Weill Cornell Medical College, Doha, Qatar
| | - Todd J Anderson
- Department of Cardiac Sciences and Libin Cardiovascular Institute, University of Calgary Cumming School of Medicine, Calgary, AB T2N 4N1, Canada
| | - Morley D Hollenberg
- Inflammation Research Network, Snyder Institute for Chronic Disease, University of Calgary Cumming School of Medicine, Calgary, AB T2N 4N1, Canada.,Department of Physiology and Pharmacology, University of Calgary Cumming School of Medicine, Calgary, AB T2N 4N1, Canada.,Department of Medicine, University of Calgary Cumming School of Medicine, Calgary, AB T2N 4N1, Canada
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4
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Gilad D, Atiya S, Mozes-Autmazgin Z, Ben-Shushan RS, Ben-David R, Amram E, Tamir S, Chuyun D, Szuchman-Sapir A. Paraoxonase 1 in endothelial cells impairs vasodilation induced by arachidonic acid lactone metabolite. Biochim Biophys Acta Mol Cell Biol Lipids 2018; 1864:386-393. [PMID: 30572120 DOI: 10.1016/j.bbalip.2018.12.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 12/13/2018] [Accepted: 12/15/2018] [Indexed: 12/15/2022]
Abstract
INTRODUCTION Paraoxonase 1 (PON1) is a high density lipoprotein (HDL)-associated lactonase, which is known for its antiatherogenic properties. Previous studies in PON1 knockout (PON1KO) mice revealed that PON1KO mice have low blood pressure, which is inversely correlated with the renal levels of the cytochrome P450 -derived arachidonic acid metabolite 5,6-epoxyeicosatrienoic acid (5,6-EET). Our previous studies revealed that 5,6-EET is unstable, transforming to the δ-lactone isomer 5,6-δ-DHTL, an endothelium-derived hyperpolarizing factor (EDHF) that mediates vasodilation, and it is a potential substrate for PON1. AIM To elucidate the role of PON1 in the modulation of vascular resistance via the regulation of the lactone-containing metabolite 5,6-δ-DHTL. RESULTS In mouse resistance arteries, PON1 was found to be present and active in the endothelial layer. Vascular reactivity experiments revealed that 5,6-δ-DHTL dose-dependently dilates PON1KO mouse mesenteric arteries significantly more than wild type (w.t.) resistance arteries. Pre-incubation with HDL or rePON1 reduced 5,6-δ-DHTL-dependent vasodilation. FACS analyses and confocal microscopy experiments revealed that fluorescence-tagged rePON1 penetrates into human endothelial cells' (ECs') in both dose- and time- dependent manner, accumulate in the perinuclear compartment, and retains its lactonase activity in the cells. The presence of rePON1, but not the presence of PON1 loss-of-lactonase-activity mutant, reduced the Ca2+ influx in the ECs mediated by 5,6-δ-DHTL. CONCLUSION PON1 lactonase activity in the endothelium affects vascular dilation by regulating Ca2+ influx mediated by the lactone-containing EDHF 5,6-δ-DHTL.
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Affiliation(s)
- Dan Gilad
- Laboratory of Vascular Signaling Research, MIGAL-Galilee Research Institute, Ltd., Kiryat Shmona, Israel; Tel-Hai College, Upper Galilee, Israel
| | - Shahar Atiya
- Laboratory of Vascular Signaling Research, MIGAL-Galilee Research Institute, Ltd., Kiryat Shmona, Israel; Tel-Hai College, Upper Galilee, Israel
| | - Ziv Mozes-Autmazgin
- Laboratory of Vascular Signaling Research, MIGAL-Galilee Research Institute, Ltd., Kiryat Shmona, Israel; Laboratory of Human Health and Nutrition Sciences, MIGAL-Galilee Research Institute, Ltd., Kiryat Shmona, Israel
| | - Rotem Shelly Ben-Shushan
- Laboratory of Vascular Signaling Research, MIGAL-Galilee Research Institute, Ltd., Kiryat Shmona, Israel
| | - Raz Ben-David
- Laboratory of Vascular Signaling Research, MIGAL-Galilee Research Institute, Ltd., Kiryat Shmona, Israel; Tel-Hai College, Upper Galilee, Israel
| | - Eytan Amram
- Laboratory of Vascular Signaling Research, MIGAL-Galilee Research Institute, Ltd., Kiryat Shmona, Israel; Tel-Hai College, Upper Galilee, Israel
| | - Snait Tamir
- Laboratory of Human Health and Nutrition Sciences, MIGAL-Galilee Research Institute, Ltd., Kiryat Shmona, Israel; Tel-Hai College, Upper Galilee, Israel
| | | | - Andrea Szuchman-Sapir
- Laboratory of Vascular Signaling Research, MIGAL-Galilee Research Institute, Ltd., Kiryat Shmona, Israel; Tel-Hai College, Upper Galilee, Israel.
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5
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Lemmey HAL, Ye X, Ding HC, Triggle CR, Garland CJ, Dora KA. Hyperglycaemia disrupts conducted vasodilation in the resistance vasculature of db/db mice. Vascul Pharmacol 2018; 103-105:29-35. [PMID: 29339138 PMCID: PMC5906692 DOI: 10.1016/j.vph.2018.01.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2017] [Revised: 11/27/2017] [Accepted: 01/10/2018] [Indexed: 11/17/2022]
Abstract
Vascular dysfunction in small resistance arteries is observed during chronic elevations in blood glucose. Hyperglycaemia-associated effects on endothelium-dependent vasodilation have been well characterized, but effects on conducted vasodilation in the resistance vasculature are not known. Small mesenteric arteries were isolated from healthy and diabetic db/db mice, which were used as a model of chronic hyperglycaemia. Endothelium-dependent vasodilation via the Gq/11-coupled proteinase activated receptor 2 (PAR2) was stimulated with the selective agonist SLIGRL. The Ca2+-sensitive fluorescent indicator fluo-8 reported changes in endothelial cell (EC) [Ca2+]i, and triple cannulated bifurcating mesenteric arteries were used to study conducted vasodilation. Chronic hyperglycaemia did not affect either EC Ca2+ or local vasodilation to SLIGRL. However, both acute and chronic exposure to high glucose or the mannitol osmotic control attenuated conducted vasodilation to 10μM SLIGRL. This investigation demonstrates for the first time that a hypertonic solution containing glucose or mannitol can interfere with the spread of a hyperpolarizing current along the endothelium in a physiological setting. Our findings reiterate the importance of studying the effects of hyperglycaemia in the vasculature, and provide the basis for further studies regarding the modulation of junctional proteins involved in cell to cell communication by diseases such as diabetes.
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Affiliation(s)
- Hamish A L Lemmey
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK.
| | - Xi Ye
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK.
| | - Hong C Ding
- Department of Pharmacology, Weill Cornell Medicine in Qatar, P.O. Box 24144, Education City, Doha, Qatar.
| | - Christopher R Triggle
- Department of Pharmacology, Weill Cornell Medicine in Qatar, P.O. Box 24144, Education City, Doha, Qatar.
| | - Christopher J Garland
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK.
| | - Kim A Dora
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK.
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6
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Manicam C, Ginter N, Li H, Xia N, Goloborodko E, Zadeh JK, Musayeva A, Pfeiffer N, Gericke A. Compensatory Vasodilator Mechanisms in the Ophthalmic Artery of Endothelial Nitric Oxide Synthase Gene Knockout Mice. Sci Rep 2017; 7:7111. [PMID: 28769073 PMCID: PMC5541003 DOI: 10.1038/s41598-017-07768-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Accepted: 06/29/2017] [Indexed: 01/02/2023] Open
Abstract
Nitric oxide (NO) generated by endothelial nitric oxide synthase (eNOS) plays an important role in the maintenance of ocular vascular homeostasis. Therefore, perturbations in vascular NO synthesis have been implicated in the pathogenesis of several ocular diseases. We recently reported that eNOS contributes significantly to vasodilation of the mouse ophthalmic artery. Interestingly, dilatory responses were also retained in eNOS gene-deficient mice (eNOS-/-), indicating inherent endothelial adaptive mechanism(s) that act as back-up systems in chronic absence of eNOS to preserve vasorelaxation. Thus, this study endeavoured to identify the compensatory mechanism(s) in the ophthalmic artery of eNOS-/- mice employing isolated arterial segments and pharmacological inhibitors in vitro. Endothelium removal virtually abolished acetylcholine (ACh)-induced vasodilation, suggesting an obligatory involvement of the endothelium in cholinergic control of vascular tone. However, non-NOS and non-cyclooxygenase components compensate for eNOS deficiency via endothelium-derived hyperpolarizing factors (EDHFs). Notably, arachidonic acid-derived metabolites of the 12-lipoxygenase pathway were key mediators in activating the inwardly rectifying potassium channels to compensate for chronic lack of eNOS. Conclusively, endothelium-dependent cholinergic responses of the ophthalmic artery in the eNOS-/- mice are largely preserved and, this vascular bed has the ability to compensate for the loss of normal vasodilator responses solely via EDHFs.
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Affiliation(s)
- Caroline Manicam
- Department of Ophthalmology, University Medical Centre of the Johannes Gutenberg University Mainz, Mainz, Germany.
| | - Natalja Ginter
- Department of Ophthalmology, University Medical Centre of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Huige Li
- Institute of Pharmacology, University Medical Centre of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Ning Xia
- Institute of Pharmacology, University Medical Centre of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Evgeny Goloborodko
- Department of Ophthalmology, University Medical Centre of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Jenia Kouchek Zadeh
- Department of Ophthalmology, University Medical Centre of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Aytan Musayeva
- Department of Ophthalmology, University Medical Centre of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Norbert Pfeiffer
- Department of Ophthalmology, University Medical Centre of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Adrian Gericke
- Department of Ophthalmology, University Medical Centre of the Johannes Gutenberg University Mainz, Mainz, Germany
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7
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Abstract
Intercellular communication between cells within the blood vessel wall plays an important role in the control of artery diameter. The endothelial cells lining the lumen of arteries can evoke smooth muscle hyperpolarization both by the release of a factor (EDHF) and by direct cell-cell coupling through gap junctions. Hyperpolarizing current can spread rapidly to cause widespread vasodilatation, and thus increase blood flow to that segment. In addition to the spread of current, small molecules, such as Ca2+, can also pass between cells, but at a much reduced rate. Instead of co-ordinating changes in diameter, intercellular Ca2+ signalling acts to amplify and, in special cases, modulate vascular responses. Together, direct cell-cell communication enables the blood vessel wall to act as a functional syncytium, which is influenced by surrounding tissues and nerves, and blood constituents.
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Affiliation(s)
- Kim A Dora
- Department of Pharmacy and Pharmacology, University of Bath, Bath, UK,
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8
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9
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Silva MAB, Bruder-Nascimento T, Cau SBA, Lopes RAM, Mestriner FLAC, Fais RS, Touyz RM, Tostes RC. Spironolactone treatment attenuates vascular dysfunction in type 2 diabetic mice by decreasing oxidative stress and restoring NO/GC signaling. Front Physiol 2015; 6:269. [PMID: 26500555 PMCID: PMC4593519 DOI: 10.3389/fphys.2015.00269] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Accepted: 09/14/2015] [Indexed: 01/26/2023] Open
Abstract
Type 2 diabetes (DM2) increases the risk of cardiovascular disease. Aldosterone, which has pro-oxidative and pro-inflammatory effects in the cardiovascular system, is positively regulated in DM2. We assessed whether blockade of mineralocorticoid receptors (MR) with spironolactone decreases reactive oxygen species (ROS)-associated vascular dysfunction and improves vascular nitric oxide (NO) signaling in diabetes. Leptin receptor knockout [LepR(db)/LepR(db) (db/db)] mice, a model of DM2, and their counterpart controls [LepR(db)/LepR(+), (db/+) mice] received spironolactone (50 mg/kg body weight/day) or vehicle (ethanol 1%) via oral per gavage for 6 weeks. Spironolactone treatment abolished endothelial dysfunction and increased endothelial nitric oxide synthase (eNOS) phosphorylation (Ser(1177)) in arteries from db/db mice, determined by acetylcholine-induced relaxation and Western Blot analysis, respectively. MR antagonist therapy also abrogated augmented ROS-generation in aorta from diabetic mice, determined by lucigenin luminescence assay. Spironolactone treatment increased superoxide dismutase-1 and catalase expression, improved sodium nitroprusside and BAY 41-2272-induced relaxation, and increased soluble guanylyl cyclase (sGC) β subunit expression in arteries from db/db mice. Our results demonstrate that spironolactone decreases diabetes-associated vascular oxidative stress and prevents vascular dysfunction through processes involving increased expression of antioxidant enzymes and sGC. These findings further elucidate redox-sensitive mechanisms whereby spironolactone protects against vascular injury in diabetes.
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Affiliation(s)
- Marcondes A B Silva
- Department of Pharmacology, Ribeirao Preto Medical School, University of Sao Paulo Ribeirão Preto, Brazil
| | - Thiago Bruder-Nascimento
- Department of Pharmacology, Ribeirao Preto Medical School, University of Sao Paulo Ribeirão Preto, Brazil
| | - Stefany B A Cau
- Department of Pharmacology, Ribeirao Preto Medical School, University of Sao Paulo Ribeirão Preto, Brazil
| | - Rheure A M Lopes
- Department of Pharmacology, Ribeirao Preto Medical School, University of Sao Paulo Ribeirão Preto, Brazil
| | - Fabiola L A C Mestriner
- Department of Pharmacology, Ribeirao Preto Medical School, University of Sao Paulo Ribeirão Preto, Brazil
| | - Rafael S Fais
- Department of Pharmacology, Ribeirao Preto Medical School, University of Sao Paulo Ribeirão Preto, Brazil
| | - Rhian M Touyz
- BHF Glasgow Cardiovascular Research Centre, Institute of Cardiovascular and Medical sciences, University of Glasgow Glasgow, UK
| | - Rita C Tostes
- Department of Pharmacology, Ribeirao Preto Medical School, University of Sao Paulo Ribeirão Preto, Brazil
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10
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A role for the sodium pump in H2O2-induced vasorelaxation in porcine isolated coronary arteries. Pharmacol Res 2014; 90:25-35. [PMID: 25258292 DOI: 10.1016/j.phrs.2014.09.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Revised: 09/08/2014] [Accepted: 09/14/2014] [Indexed: 01/17/2023]
Abstract
Hydrogen peroxide (H2O2) has been proposed to act as a factor for endothelium-derived hyperpolarization (EDH) and EDH may act as a 'back up' system to compensate the loss of the NO pathway. Here, the mechanism of action of H2O2 in porcine isolated coronary arteries (PCAs) was investigated. Distal PCAs were mounted in a wire myograph and pre-contracted with U46619 (1nM-50μM), a thromboxane A2-mimetic or KCl (60mM). Concentration-response curves to H2O2(1μM-1mM), bradykinin (0.01nM-1μM), sodium nitroprusside (SNP) (10nM-10μM), verapamil (1nM-10μM), KCl (0-20mM) or Ca(2+)-reintroduction (1μM-10mM) were constructed in the presence of various inhibitors. Activity of the Na(+)/K(+)-pump was measured through rubidium-uptake using atomic absorption spectrophotometry. H2O2 caused concentration-dependent vasorelaxations with a maximum relaxation (Rmax) of 100±16% (mean±SEM), pEC50=4.18±0.20 (n=4) which were significantly inhibited by PEG-catalase at 0.1-1.0mM H2O2 (P<0.05). 10mM TEA significantly inhibited the relaxation up to 100μM H2O2 (P<0.05). 60mM K(+) and 500nM ouabain significantly inhibited H2O2-induced vasorelaxation producing a relaxation of 40.8±8.5% (n=5) and 47.5±8.6% (n=6) respectively at 1mM H2O2 (P<0.0001). H2O2-induced vasorelaxation was unaffected by the removal of endothelium, inhibition of NO, cyclo-oxygenase, gap junctions, SKCa, IKCa, BKCa Kir, KV, KATP or cGMP. 100μM H2O2 had no effects on the KCl-induced vasorelaxation or Ca(2+)-reintroduction contraction. 1mM H2O2 inhibited both KCl-induced vasorelaxation and rubidium-uptake consistent with inhibition of the Na(+)/K(+)-pump activity. We have shown that the vascular actions of H2O2 are sensitive to ouabain and high concentrations of H2O2 are able to modulate the Na(+)/K(+)-pump. This may contribute towards its vascular actions.
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11
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Ma X, Du J, Zhang P, Deng J, Liu J, Lam FFY, Li RA, Huang Y, Jin J, Yao X. Functional Role of TRPV4-K
Ca
2.3 Signaling in Vascular Endothelial Cells in Normal and Streptozotocin-Induced Diabetic Rats. Hypertension 2013; 62:134-9. [DOI: 10.1161/hypertensionaha.113.01500] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The small conductance and intermediate conductance Ca
2+
-activated K
+
channels are known to be involved in the endothelium-dependent hyperpolarization. Ca
2+
entry into endothelial cells stimulates these channels, causing membrane hyperpolarization in endothelial cells and underlying smooth muscle cells. In the present study, with the use of coimmunoprecipitation and double immunolabeling methods, we demonstrated a physical interaction of transient receptor potential vanilloid 4 (TRPV4) with K
Ca
2.3 in rat mesenteric artery endothelial cells. Acetylcholine and 4α-PDD mainly acted through TRPV4-K
Ca
2.3 pathway to induce smooth muscle hyperpolarization and vascular relaxation. K
Ca
3.1 was also involved in the process but at a much lesser degree than that of K
Ca
2.3. Stimulating TRPV4-K
Ca
2.3 signaling pathway also increased local blood flow in mesenteric beds and reduced systemic blood pressure in anesthetized rats. In streptozotocin-induced diabetic rats, the expression levels of TRPV4 and K
Ca
2.3 were reduced, which could be an underlying reason for the dysfunction of endothelium-dependent hyperpolarization in these animals. These results demonstrated an important physiological and pathological role of TRPV4-K
Ca
2.3 signaling pathway in vascular endothelial cells.
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Affiliation(s)
- Xin Ma
- From the School of Medicine and Pharmaceutics, Jiangnan University, Wuxi, China (X.M., J.J., X.Y.); School of Biomedical Sciences (X.M., J.D., P.Z., F.F.-Y.L., Y.H., X.Y.) and Shenzhen Research Institute (P.Z., X.Y.), Chinese University of Hong Kong, Hong Kong, China; Department of Physiology, Anhui Medical University, Hefei, China (J.D., X.Y.); Department of Pathophysiology, Southern Medical University, Guangzhou, China (J.De.); Department of Pathophysiology, Shenzhen University, Shenzhen, China (J
| | - Juan Du
- From the School of Medicine and Pharmaceutics, Jiangnan University, Wuxi, China (X.M., J.J., X.Y.); School of Biomedical Sciences (X.M., J.D., P.Z., F.F.-Y.L., Y.H., X.Y.) and Shenzhen Research Institute (P.Z., X.Y.), Chinese University of Hong Kong, Hong Kong, China; Department of Physiology, Anhui Medical University, Hefei, China (J.D., X.Y.); Department of Pathophysiology, Southern Medical University, Guangzhou, China (J.De.); Department of Pathophysiology, Shenzhen University, Shenzhen, China (J
| | - Peng Zhang
- From the School of Medicine and Pharmaceutics, Jiangnan University, Wuxi, China (X.M., J.J., X.Y.); School of Biomedical Sciences (X.M., J.D., P.Z., F.F.-Y.L., Y.H., X.Y.) and Shenzhen Research Institute (P.Z., X.Y.), Chinese University of Hong Kong, Hong Kong, China; Department of Physiology, Anhui Medical University, Hefei, China (J.D., X.Y.); Department of Pathophysiology, Southern Medical University, Guangzhou, China (J.De.); Department of Pathophysiology, Shenzhen University, Shenzhen, China (J
| | - Jianxin Deng
- From the School of Medicine and Pharmaceutics, Jiangnan University, Wuxi, China (X.M., J.J., X.Y.); School of Biomedical Sciences (X.M., J.D., P.Z., F.F.-Y.L., Y.H., X.Y.) and Shenzhen Research Institute (P.Z., X.Y.), Chinese University of Hong Kong, Hong Kong, China; Department of Physiology, Anhui Medical University, Hefei, China (J.D., X.Y.); Department of Pathophysiology, Southern Medical University, Guangzhou, China (J.De.); Department of Pathophysiology, Shenzhen University, Shenzhen, China (J
| | - Jie Liu
- From the School of Medicine and Pharmaceutics, Jiangnan University, Wuxi, China (X.M., J.J., X.Y.); School of Biomedical Sciences (X.M., J.D., P.Z., F.F.-Y.L., Y.H., X.Y.) and Shenzhen Research Institute (P.Z., X.Y.), Chinese University of Hong Kong, Hong Kong, China; Department of Physiology, Anhui Medical University, Hefei, China (J.D., X.Y.); Department of Pathophysiology, Southern Medical University, Guangzhou, China (J.De.); Department of Pathophysiology, Shenzhen University, Shenzhen, China (J
| | - Francis Fu-Yuen Lam
- From the School of Medicine and Pharmaceutics, Jiangnan University, Wuxi, China (X.M., J.J., X.Y.); School of Biomedical Sciences (X.M., J.D., P.Z., F.F.-Y.L., Y.H., X.Y.) and Shenzhen Research Institute (P.Z., X.Y.), Chinese University of Hong Kong, Hong Kong, China; Department of Physiology, Anhui Medical University, Hefei, China (J.D., X.Y.); Department of Pathophysiology, Southern Medical University, Guangzhou, China (J.De.); Department of Pathophysiology, Shenzhen University, Shenzhen, China (J
| | - Ronald A. Li
- From the School of Medicine and Pharmaceutics, Jiangnan University, Wuxi, China (X.M., J.J., X.Y.); School of Biomedical Sciences (X.M., J.D., P.Z., F.F.-Y.L., Y.H., X.Y.) and Shenzhen Research Institute (P.Z., X.Y.), Chinese University of Hong Kong, Hong Kong, China; Department of Physiology, Anhui Medical University, Hefei, China (J.D., X.Y.); Department of Pathophysiology, Southern Medical University, Guangzhou, China (J.De.); Department of Pathophysiology, Shenzhen University, Shenzhen, China (J
| | - Yu Huang
- From the School of Medicine and Pharmaceutics, Jiangnan University, Wuxi, China (X.M., J.J., X.Y.); School of Biomedical Sciences (X.M., J.D., P.Z., F.F.-Y.L., Y.H., X.Y.) and Shenzhen Research Institute (P.Z., X.Y.), Chinese University of Hong Kong, Hong Kong, China; Department of Physiology, Anhui Medical University, Hefei, China (J.D., X.Y.); Department of Pathophysiology, Southern Medical University, Guangzhou, China (J.De.); Department of Pathophysiology, Shenzhen University, Shenzhen, China (J
| | - Jian Jin
- From the School of Medicine and Pharmaceutics, Jiangnan University, Wuxi, China (X.M., J.J., X.Y.); School of Biomedical Sciences (X.M., J.D., P.Z., F.F.-Y.L., Y.H., X.Y.) and Shenzhen Research Institute (P.Z., X.Y.), Chinese University of Hong Kong, Hong Kong, China; Department of Physiology, Anhui Medical University, Hefei, China (J.D., X.Y.); Department of Pathophysiology, Southern Medical University, Guangzhou, China (J.De.); Department of Pathophysiology, Shenzhen University, Shenzhen, China (J
| | - Xiaoqiang Yao
- From the School of Medicine and Pharmaceutics, Jiangnan University, Wuxi, China (X.M., J.J., X.Y.); School of Biomedical Sciences (X.M., J.D., P.Z., F.F.-Y.L., Y.H., X.Y.) and Shenzhen Research Institute (P.Z., X.Y.), Chinese University of Hong Kong, Hong Kong, China; Department of Physiology, Anhui Medical University, Hefei, China (J.D., X.Y.); Department of Pathophysiology, Southern Medical University, Guangzhou, China (J.De.); Department of Pathophysiology, Shenzhen University, Shenzhen, China (J
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Thoonen R, Sips PY, Bloch KD, Buys ES. Pathophysiology of hypertension in the absence of nitric oxide/cyclic GMP signaling. Curr Hypertens Rep 2013; 15:47-58. [PMID: 23233080 DOI: 10.1007/s11906-012-0320-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The nitric oxide (NO)-cyclic guanosine monophosphate (cGMP) signaling system is a well-characterized modulator of cardiovascular function, in general, and blood pressure, in particular. The availability of mice mutant for key enzymes in the NO-cGMP signaling system facilitated the identification of interactions with other blood pressure modifying pathways (e.g. the renin-angiotensin-aldosterone system) and of gender-specific effects of impaired NO-cGMP signaling. In addition, recent genome-wide association studies identified blood pressure-modifying genetic variants in genes that modulate NO and cGMP levels. Together, these findings have advanced our understanding of how NO-cGMP signaling regulates blood pressure. In this review, we will summarize the results obtained in mice with disrupted NO-cGMP signaling and highlight the relevance of this pathway as a potential therapeutic target for the treatment of hypertension.
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Affiliation(s)
- Robrecht Thoonen
- Molecular Cardiology Research Institute, Molecular Cardiology Research Center, Tufts Medical Center, Boston, MA 02111, USA.
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13
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Simonet S, Isabelle M, Bousquenaud M, Clavreul N, Félétou M, Vayssettes-Courchay C, Verbeuren TJ. KCa 3.1 channels maintain endothelium-dependent vasodilatation in isolated perfused kidneys of spontaneously hypertensive rats after chronic inhibition of NOS. Br J Pharmacol 2013; 167:854-67. [PMID: 22646737 DOI: 10.1111/j.1476-5381.2012.02062.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND AND PURPOSE The purpose of the study was to investigate renal endothelium-dependent vasodilatation in a model of severe hypertension associated with kidney injury. EXPERIMENTAL APPROACH Changes in perfusion pressure were measured in isolated, perfused kidneys taken from 18-week-old Wistar-Kyoto rat (WKY), spontaneously hypertensive rats (SHR) and SHR treated for 2 weeks with N(ω) -nitro-L-arginine methyl ester in the drinking water (L-NAME-treated SHR, 6 mg·kg(-1) ·day(-1) ). KEY RESULTS Acetylcholine caused similar dose-dependent renal dilatation in the three groups. In vitro administration of indomethacin did not alter the vasodilatation, while the addition of N(w) -nitro-L-arginine (L-NA) produced a differential inhibition of the vasodilatation, (inhibition in WKY > SHR > L-NAME-treated SHR). Further addition of ODQ, an inhibitor of soluble guanylyl cyclase, abolished the responses to sodium nitroprusside but did not affect the vasodilatation to acetylcholine. However, the addition of TRAM-34 (or charybdotoxin) inhibitors of Ca(2+) -activated K(+) channels of intermediate conductance (K(Ca) 3.1), blocked the vasodilatation to acetylcholine, while apamin, an inhibitor of Ca(2+) -activated K(+) channels of small conductance (K(Ca) 2.3), was ineffective. Dilatation induced by an opener of K(Ca) 3.1/K(Ca) 2.3 channels, NS-309, was also blocked by TRAM-34, but not by apamin. The magnitude and duration of NS-309-induced vasodilatation and the renal expression of mRNA for K(Ca) 3.1, but not K(Ca) 2.3, channels followed the same ranking order (WKY < SHR < L-NAME-treated SHR). CONCLUSIONS AND IMPLICATIONS In SHR kidneys, an EDHF-mediated response, involving activation of K(Ca) 3.1 channels, contributed to the mechanism of endothelium-dependent vasodilatation. In kidneys from L-NAME-treated SHR, up-regulation of this pathway fully compensated for the decrease in NO availability.
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14
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The contribution of d-tubocurarine-sensitive and apamin-sensitive K-channels to EDHF-mediated relaxation of mesenteric arteries from eNOS-/- mice. J Cardiovasc Pharmacol 2012; 59:413-25. [PMID: 22217882 DOI: 10.1097/fjc.0b013e318248acd9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The nature of the potassium channels involved in determining endothelium-derived hyperpolarizing factor-mediated relaxation was investigated in first-order small mesenteric arteries from male endothelial nitric oxide synthase (eNOS-/-)-knockout and control (+/+) mice. Acetylcholine-induced endothelium-dependent relaxation of small mesenteric arteries of eNOS-/- was resistant to N-nitro-L-arginine and indomethacin and the guanylyl cyclase inhibitor, 1H-(1,2,4) oxadiazolo (4,3-a) quinoxalin-1-one. Apamin and the combination of apamin and iberiotoxin or apamin and charybdotoxin induced a transient endothelium-dependent contraction of small mesenteric arteries from both eNOS-/- and +/+ mice. Acetylcholine-induced relaxation in eNOS-/- mice was unaffected by charybdotoxin or apamin alone but significantly inhibited by the combination of these agents. However, the combination of scyllatoxin and iberiotoxin did not mimic the inhibitory effect of the apamin/charybdotoxin combination. Tubocurarine alone completely blocked acetylcholine-induced relaxation in eNOS-/- mice. Single channel analysis of myocytes from small mesenteric arterioles revealed a large conductance calcium-activated potassium channel that was sensitive to iberiotoxin, charybdotoxin, and tetraethylammonium. Tubocurarine blocked this channel from the cytosolic side but not when applied extracellularly. Solutions of nitric oxide (NO) gas also relaxed small mesenteric arteries that had been contracted with cirazoline in a concentration-dependent manner, and the sensitivity to NO was reduced by iberiotoxin and the combination of apamin, scyllatoxin, or tubocurarine with charybdotoxin but not by apamin, charybdotoxin, scyllatoxin, or tubocurarine alone. These data indicate that acetylcholine-induced endothelium-derived hyperpolarizing factor-mediated relaxation in small mesenteric arteries from eNOS-/- involved the activation of tubocurarine and apamin-/charybdotoxin-sensitive K-channels. In eNOS+/+ mice, the acetylcholine-induced response was primarily mediated by NO and was sensitive to iberiotoxin and the combination of apamin and charybdotoxin.
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15
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Looft-Wilson RC, Billaud M, Johnstone SR, Straub AC, Isakson BE. Interaction between nitric oxide signaling and gap junctions: effects on vascular function. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1818:1895-902. [PMID: 21835160 DOI: 10.1016/j.bbamem.2011.07.031] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2011] [Revised: 07/14/2011] [Accepted: 07/19/2011] [Indexed: 02/07/2023]
Abstract
Nitric oxide signaling, through eNOS (or possibly nNOS), and gap junction communication are essential for normal vascular function. While each component controls specific aspects of vascular function, there is substantial evidence for cross-talk between nitric oxide signaling and the gap junction proteins (connexins), and more recently, protein-protein association between eNOS and connexins. This review will examine the evidence for interaction between these pathways in normal and diseased arteries, highlight the questions that remain about the mechanisms of their interaction, and explore the possible interaction between nitric oxide signaling and the newly discovered pannexin channels. This article is part of a Special Issue entitled: The Communicating junctions, composition, structure and characteristics.
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Affiliation(s)
- R C Looft-Wilson
- Department of Kinesiology and Health Sciences, College of William and Mary, Williamsburg, VA 23187, USA
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16
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Félétou M. The Endothelium, Part I: Multiple Functions of the Endothelial Cells -- Focus on Endothelium-Derived Vasoactive Mediators. ACTA ACUST UNITED AC 2011. [DOI: 10.4199/c00031ed1v01y201105isp019] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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18
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Miura H, Toyama K, Pratt PF, Gutterman DD. Cigarette smoking impairs Na+-K+-ATPase activity in the human coronary microcirculation. Am J Physiol Heart Circ Physiol 2010; 300:H109-17. [PMID: 21076023 DOI: 10.1152/ajpheart.00237.2010] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The extracellular K(+) concentration ([K(+)](o)) has been proposed to link cardiac metabolism with coronary perfusion and arrhythmogenesis, particularly during ischemia. Several animal studies have also supported K(+) as an EDHF that activates Na(+)-K(+)-ATPase and/or inwardly rectifying K(+) (K(ir)) channels. Therefore, we examined the vascular reactivity of human coronary arterioles (HCAs) to small elevations in [K(+)](o), the influence of risk factors for coronary disease, and the role of K(+) as an EDHF. Changes in the internal diameter of HCAs were recorded with videomicroscopy. Most vessels dilated to increases in [K(+)](o) with a maximal dilation of 55 ± 6% primarily at 12.5-20.0 mM KCl (n = 38, average: 16 ± 1 mM). Ouabain, a Na(+)-K(+)-ATPase inhibitor, alone reduced the dilation, and the addition of Ba(2+), a K(ir) channel blocker, abolished the remaining dilation, whereas neither endothelial denudation nor Ba(2+) alone reduced the dilation. Multivariate analysis revealed that cigarette smoking was the only risk factor associated with impaired dilation to K(+). Ouabain significantly reduced the vasodilation in HCAs from subjects without cigarette smoking but not in those with smoking. Cigarette smoking downregulated the expression of the Na(+)-K(+)-ATPase catalytic α(1)-subunit but not Kir2.1 in the vessels. Ouabain abolished the dilation in endothelium-denuded vessels to a same extent to that with the combination of ouabain and Ba(2+) in endothelium-intact vessels, whereas neither ouabain nor ouabain plus Ba(2+) reduced EDHF-mediated dilations to bradykinin and ADP. A rise in [K(+)](o) dilates HCAs primarily via the activation of Na(+)-K(+)-ATPase in vascular smooth muscle cells with a considerable contribution of K(ir) channels in the endothelium, indicating that [K(+)](o) may modify coronary microvascular resistance in humans. Na(+)-K(+)-ATPase activity is impaired in subjects who smoke, possibly contributing to dysregulation of the coronary microcirculation, excess ischemia, and arrhythmogenesis in those subjects. K(+) does not likely serve as an EDHF in the human coronary arteriolar dilation to bradykinin and ADP.
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Affiliation(s)
- Hiroto Miura
- Department of Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.
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Characterization of vasoconstrictor-induced relaxation in the cerebral basilar artery. Eur J Pharmacol 2010; 637:118-23. [DOI: 10.1016/j.ejphar.2010.03.045] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2009] [Revised: 03/08/2010] [Accepted: 03/14/2010] [Indexed: 11/19/2022]
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Mendoza SA, Fang J, Gutterman DD, Wilcox DA, Bubolz AH, Li R, Suzuki M, Zhang DX. TRPV4-mediated endothelial Ca2+ influx and vasodilation in response to shear stress. Am J Physiol Heart Circ Physiol 2009; 298:H466-76. [PMID: 19966050 DOI: 10.1152/ajpheart.00854.2009] [Citation(s) in RCA: 242] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The transient receptor potential vallinoid type 4 (TRPV4) channel has been implicated in the endothelial shear response and flow-mediated dilation, although the precise functions of this channel remain poorly understood. In the present study, we investigated the role of TRPV4 in shear stress-induced endothelial Ca(2+) entry and the potential link between this signaling response and relaxation of small resistance arteries. Using immunohistochemical analysis and RT-PCR, we detected strong expression of TRPV4 protein and mRNA in the endothelium in situ and endothelial cells freshly isolated from mouse small mesenteric arteries. The selective TRPV4 agonist GSK1016790A increased endothelial Ca(2+) and induced potent relaxation of small mesenteric arteries from wild-type (WT) but not TRPV4(-/-) mice. Luminal flow elicited endothelium-dependent relaxations that involved both nitric oxide and EDHFs. Both nitric oxide and EDHF components of flow-mediated relaxation were markedly reduced in TRPV4(-/-) mice compared with WT controls. Using a fura-2/Mn(2+) quenching assay, shear was observed to produce rapid Ca(2+) influx in endothelial cells, which was markedly inhibited by the TRPV4 channel blocker ruthenium red and TRPV4-specific short interfering RNA. Flow elicited a similar TRPV4-mediated Ca(2+) entry in HEK-293 cells transfected with TRPV4 channels but not in nontransfected cells. Collectively, these data indicate that TRPV4 may be a potential candidate of mechanosensitive channels in endothelial cells through which the shear stimulus is transduced into Ca(2+) signaling, leading to the release of endothelial relaxing factors and flow-mediated dilation of small resistance arteries.
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Affiliation(s)
- Suelhem A Mendoza
- Department of Medicine, Medical College of Wisconsin, 8701 Watertown Plank Rd., Milwaukee, WI 53226, USA
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Abstract
Vascular complications are an important pathological issue in diabetes that lead to the further functional deterioration of several organs. The balance between endothelium-dependent relaxing factors and endothelium-dependent contracting factors (EDCFs) is crucial in controlling local vascular tone and function under normal conditions. Diabetic endothelial dysfunction is characterized by reduced endothelium-dependent relaxations and/or enhanced endothelium-dependent contractions. Elevated levels of oxygen-derived free radicals are the initial source of endothelial dysfunction in diabetes. Oxygen-derived free radicals not only reduce nitric oxide bioavailability, but also facilitate the production and/or action of EDCFs. Thus, the endothelial balance tips towards vasoconstrictor responses over the course of diabetes.
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Affiliation(s)
- Yi Shi
- Institute of Physiology, University of Zurich, Switzerland
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22
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Gschwend S, Haug MB, Nierhaus M, Schulz A, Vetter R, Kossmehl P, Orzechowski HD, Scholze J, Rothermund L, Kreutz R. Short-term treatment with a beta-blocker with vasodilative capacities improves intrarenal endothelial function in experimental renal failure. Life Sci 2009; 85:431-7. [PMID: 19635487 DOI: 10.1016/j.lfs.2009.07.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2009] [Revised: 07/06/2009] [Accepted: 07/10/2009] [Indexed: 01/11/2023]
Abstract
AIMS In patients with renal disease the cardiovascular risk is greatly increased, and endothelial dysfunction is assumed to play a pivotal role in this process. Therefore we compared treatment effects of a beta-blocker with additional vasodilatory capacities (nebivolol) and a beta-blocker lacking these actions (metoprolol) on intrarenal and coronary vascular function in a rat model of renal failure with hypertension. MAIN METHODS Renal failure was induced by 5/6-nephrectomy (Nx) and analyzed after 4 weeks in Wistar rats. Untreated Nx, Nx/nebivolol 6 mg/d (Nx-Nebi); Nx/metoprolol 60 mg/d (Nx-Meto) and sham-operated (Sham) animals were studied. Isolated small renal and coronary arteries were investigated for endothelium-dependent relaxation to acetylcholine (ACh) and for the contribution of the endothelial mediators NO and endothelium-derived hyperpolarizing factor (EDHF). KEY FINDINGS Systolic blood pressure (SBP) was significantly increased in Nx, Nx-Nebi, and Nx-Meto (168+/-5, 153+/-3, and 162+/-6 mmHg) compared to Sham (138+/-3 mmHg, p<0.05, respectively). The increase in albuminuria of Nx (120-fold vs. Sham, p<0.0001) was almost (-85%) normalized by nebivolol compared to Sham (p<0.05), whereas metoprolol induced no significant effect. Renal arteries showed significantly increased Ach-relaxation in Nx and Nx-Nebi (Emax 86+/-4% and 76+/-7%, p<0.05) due to an increase in EDHF-mediated dilation (Emax_EDHF 78+/-7% and 73+/-6%) compared to Sham (Emax 54+/-4% and Emax_EDHF 44+/-6%) and Nx-Meto (Emax 42+/-12% and Emax_EDHF 18+/-5%). ACh-relaxation in coronary arteries was similar between groups but the contribution of NO (relative to EDHF) was strongly increased by nebivolol. SIGNIFICANCE The present findings offer an explanation of the nephroprotective effect of intrarenal endothelial function in renal failure.
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Affiliation(s)
- Simone Gschwend
- Institut für Klinische Pharmakologie und Toxikologie, Charité Centrum für Therapieforschung, Germany
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Andrews KL, Irvine JC, Tare M, Apostolopoulos J, Favaloro JL, Triggle CR, Kemp-Harper BK. A role for nitroxyl (HNO) as an endothelium-derived relaxing and hyperpolarizing factor in resistance arteries. Br J Pharmacol 2009; 157:540-50. [PMID: 19338582 DOI: 10.1111/j.1476-5381.2009.00150.x] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND AND PURPOSE Nitroxyl (HNO) is emerging as an important regulator of vascular tone as it is potentially produced endogenously and dilates conduit and resistance arteries. This study investigates the contribution of endogenous HNO to endothelium-dependent relaxation and hyperpolarization in resistance arteries. EXPERIMENTAL APPROACH Rat and mouse mesenteric arteries were mounted in small vessel myographs for isometric force and smooth muscle membrane potential recording. KEY RESULTS Vasorelaxation to the HNO donor, Angeli's salt, was attenuated in both species by the soluble guanylate cyclase inhibitor (ODQ, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxaline-1-one), the voltage-dependent K(+) channel inhibitor, 4-aminopyridine (4-AP) and the HNO scavenger, L-cysteine. In mouse mesenteric arteries, nitric oxide (NO) synthase inhibition (with L-NAME, N(omega)-Nitro-L-arginine methyl ester) markedly attenuated acetylcholine (ACh)-mediated relaxation. Scavenging the uncharged form of NO (NO(*)) with hydroxocobalamin (HXC) or HNO with L-cysteine, or 4-AP decreased the sensitivity to ACh, and a combination of HXC and L-cysteine reduced ACh-mediated relaxation, as did L-NAME alone. ACh-induced hyperpolarizations were significantly attenuated by 4-AP alone and in combination with L-NAME. In rat mesenteric arteries, blocking the effects of endothelium-derived hyperpolarizing factor (EDHF) (charybdotoxin and apamin) decreased ACh-mediated relaxation 10-fold and unmasked a NO-dependent component, mediated equally by HNO and NO(*), as HXC and L-cysteine in combination now abolished vasorelaxation to ACh. Furthermore, ACh-evoked hyperpolarizations, resistant to EDHF inhibition, were virtually abolished by 4-AP. CONCLUSIONS AND IMPLICATIONS The factors contributing to vasorelaxation in mouse and rat mesenteric arteries are NO(*) = HNO > EDHF and EDHF > HNO = NO(*) respectively. This study identified HNO as an endothelium-derived relaxing and hyperpolarizing factor in resistance vessels.
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Affiliation(s)
- Karen L Andrews
- Discipline of Pharmaceutical Sciences, RMIT University, Bundoora, Victoria, Australia
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Zhang DX, Mendoza SA, Bubolz AH, Mizuno A, Ge ZD, Li R, Warltier DC, Suzuki M, Gutterman DD. Transient receptor potential vanilloid type 4-deficient mice exhibit impaired endothelium-dependent relaxation induced by acetylcholine in vitro and in vivo. Hypertension 2009; 53:532-8. [PMID: 19188524 DOI: 10.1161/hypertensionaha.108.127100] [Citation(s) in RCA: 157] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Agonist-induced Ca2+ entry is important for the synthesis and release of vasoactive factors in endothelial cells. The transient receptor potential vanilloid type 4 (TRPV4) channel, a Ca2+-permeant cation channel, is expressed in endothelial cells and involved in the regulation of vascular tone. Here we investigated the role of TRPV4 channels in acetylcholine-induced vasodilation in vitro and in vivo using the TRPV4 knockout mouse model. The expression of TRPV4 mRNA and protein was detected in both conduit and resistance arteries from wild-type mice. In small mesenteric arteries from wild-type mice, the TRPV4 activator 4alpha-phorbol-12,13-didecanoate increased endothelial [Ca2+]i in situ, which was reversed by the TRPV4 blocker ruthenium red. In wild-type animals, acetylcholine dilated small mesenteric arteries that involved both NO and endothelium-derived hyperpolarizing factors. In TRPV4-deficient mice, the NO component of the relaxation was attenuated and the endothelium-derived hyperpolarizing factor component was largely eliminated. Compared with their wild-type littermates, TRPV4-deficient mice demonstrated a blunted endothelial Ca2+ response to acetylcholine in mesenteric arteries and reduced NO release in carotid arteries. Acetylcholine (5 mg/kg, IV) decreased blood pressure by 37.0+/-6.2 mm Hg in wild-type animals but only 16.6+/-2.7 mm Hg in knockout mice. We conclude that acetylcholine-induced endothelium-dependent vasodilation is reduced both in vitro and in vivo in TRPV4 knockout mice. These findings may provide novel insight into mechanisms of Ca2+ entry evoked by chemical agonists in endothelial cells.
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Affiliation(s)
- David X Zhang
- Department of Medicine, Medical College of Wisconsin, 8701 Watertown Plank Rd, Milwaukee, WI 53226, USA.
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Félétou M. Calcium-activated potassium channels and endothelial dysfunction: therapeutic options? Br J Pharmacol 2009; 156:545-62. [PMID: 19187341 DOI: 10.1111/j.1476-5381.2009.00052.x] [Citation(s) in RCA: 184] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
The three subtypes of calcium-activated potassium channels (K(Ca)) of large, intermediate and small conductance (BK(Ca), IK(Ca) and SK(Ca)) are present in the vascular wall. In healthy arteries, BK(Ca) channels are preferentially expressed in vascular smooth muscle cells, while IK(Ca) and SK(Ca) are preferentially located in endothelial cells. The activation of endothelial IK(Ca) and SK(Ca) contributes to nitric oxide (NO) generation and is required to elicit endothelium-dependent hyperpolarizations. In the latter responses, the hyperpolarization of the smooth muscle cells is evoked either via electrical coupling through myo-endothelial gap junctions or by potassium ions, which by accumulating in the intercellular space activate the inwardly rectifying potassium channel Kir2.1 and/or the Na(+)/K(+)-ATPase. Additionally, endothelium-derived factors such as cytochrome P450-derived epoxyeicosatrienoic acids and under some circumstances NO, prostacyclin, lipoxygenase products and hydrogen peroxide (H(2)O(2)) hyperpolarize and relax the underlying smooth muscle cells by activating BK(Ca). In contrast, cytochrome P450-derived 20-hydroxyeicosatetraenoic acid and various endothelium-derived contracting factors inhibit BK(Ca). Aging and cardiovascular diseases are associated with endothelial dysfunctions that can involve a decrease in NO bioavailability, alterations of EDHF-mediated responses and/or enhanced production of endothelium-derived contracting factors. Because potassium channels are involved in these endothelium-dependent responses, activation of endothelial and/or smooth muscle K(Ca) could prevent the occurrence of endothelial dysfunction. Therefore, direct activators of these potassium channels or compounds that regulate their activity or their expression may be of some therapeutic interest. Conversely, blockers of IK(Ca) may prevent restenosis and that of BK(Ca) channels sepsis-dependent hypotension.
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Affiliation(s)
- Michel Félétou
- Department of Angiology, Institut de Recherches Servier, Suresnes, France.
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Takaki A, Morikawa K, Tsutsui M, Murayama Y, Tekes E, Yamagishi H, Ohashi J, Yada T, Yanagihara N, Shimokawa H. Crucial role of nitric oxide synthases system in endothelium-dependent hyperpolarization in mice. J Exp Med 2008; 205:2053-63. [PMID: 18695006 PMCID: PMC2526200 DOI: 10.1084/jem.20080106] [Citation(s) in RCA: 113] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2008] [Accepted: 07/02/2008] [Indexed: 11/04/2022] Open
Abstract
The endothelium plays an important role in maintaining vascular homeostasis by synthesizing and releasing several relaxing factors, such as prostacyclin, nitric oxide (NO), and endothelium-derived hyperpolarizing factor (EDHF). We have previously demonstrated in animals and humans that endothelium-derived hydrogen peroxide (H(2)O(2)) is an EDHF that is produced in part by endothelial NO synthase (eNOS). In this study, we show that genetic disruption of all three NOS isoforms (neuronal [nNOS], inducible [iNOS], and endothelial [eNOS]) abolishes EDHF responses in mice. The contribution of the NOS system to EDHF-mediated responses was examined in eNOS(-/-), n/eNOS(-/-), and n/i/eNOS(-/-) mice. EDHF-mediated relaxation and hyperpolarization in response to acetylcholine of mesenteric arteries were progressively reduced as the number of disrupted NOS genes increased, whereas vascular smooth muscle function was preserved. Loss of eNOS expression alone was compensated for by other NOS genes, and endothelial cell production of H(2)O(2) and EDHF-mediated responses were completely absent in n/i/eNOS(-/-) mice, even after antihypertensive treatment with hydralazine. NOS uncoupling was not involved, as modulation of tetrahydrobiopterin (BH(4)) synthesis had no effect on EDHF-mediated relaxation, and the BH(4)/dihydrobiopterin (BH(2)) ratio was comparable in mesenteric arteries and the aorta. These results provide the first evidence that EDHF-mediated responses are dependent on the NOSs system in mouse mesenteric arteries.
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Affiliation(s)
- Aya Takaki
- Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan
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Park WS, Han J, Earm YE. Physiological role of inward rectifier K+ channels in vascular smooth muscle cells. Pflugers Arch 2008; 457:137-47. [DOI: 10.1007/s00424-008-0512-7] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2007] [Revised: 03/19/2008] [Accepted: 03/25/2008] [Indexed: 10/22/2022]
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Gaubert ML, Sigaudo-Roussel D, Tartas M, Berrut G, Saumet JL, Fromy B. Endothelium-derived hyperpolarizing factor as an in vivo back-up mechanism in the cutaneous microcirculation in old mice. J Physiol 2007; 585:617-26. [PMID: 17932144 DOI: 10.1113/jphysiol.2007.143750] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
There is now strong evidence that an endothelium-derived hyperpolarizing factor (EDHF), other than nitric oxide (NO) or prostaglandin (PG), exists for dilating arteries and arterioles. In vitro studies on isolated vessels pointed out a role for EDHF as a back-up mechanism when the NO pathway is impaired, but there was a lack of in vivo studies showing a functional role for EDHF. Ageing has pronounced effects on vascular function and particularly on endothelium-dependent relaxation, providing a novel situation in which to assess the contributions of EDHF. The purpose of the present study was thus to determine if, in vivo, there was a functional role for EDHF as a back-up mechanism in the cutaneous microcirculation in the ageing process. We investigated in vivo the contribution of each endothelial factor (NO, PG and EDHF) in the cutaneous vasodilatation induced by iontophoretic delivery of acetylcholine and local pressure application in young adult (6-7 months) and old (22-25 months) mice, using pharmacological inhibitors. The cutaneous vasodilator responses induced by acetylcholine and local pressure application were dependent upon NO and PG pathways in young adult mice, whereas they were EDHF-dependent in old mice. EDHF appears to serve as a back-up mechanism when ageing reaches pathological states in terms of the ability for NO and PG to relax cutaneous microvessels, allowing for persistent cutaneous vasodilatator responses in old mice. However, as a back-up mechanism, EDHF did not completely restore cutaneous vasodilatation, since endothelial responses were reduced in old mice compared to young adult mice.
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Affiliation(s)
- Marie Line Gaubert
- Integrative neuro-vascular biology, UMR CNRS 6214-INSERM 771, Medical School, University of Angers, France
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Fitzgerald SM, Kemp-Harper BK, Parkington HC, Head GA, Evans RG. Endothelial dysfunction and arterial pressure regulation during early diabetes in mice: roles for nitric oxide and endothelium-derived hyperpolarizing factor. Am J Physiol Regul Integr Comp Physiol 2007; 293:R707-13. [PMID: 17522117 DOI: 10.1152/ajpregu.00807.2006] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We determined whether nitric oxide (NO) counters the development of hypertension at the onset of diabetes in mice, whether this is dependent on endothelial NO synthase (eNOS), and whether non-NO endothelium-dependent vasodilator mechanisms are altered in diabetes in mice. Male mice were instrumented for chronic measurement of mean arterial pressure (MAP). In wild-type mice, MAP was greater after 5 wk of N(omega)-nitro-L-arginine methyl ester (L-NAME; 100 mg x kg(-1) x day(-1) in drinking water; 97 +/- 3 mmHg) than after vehicle treatment (88 +/- 3 mmHg). MAP was also elevated in eNOS null mice (113 +/- 4 mmHg). Seven days after streptozotocin treatment (200 mg/kg iv) MAP was further increased in L-NAME-treated mice (108 +/- 5 mmHg) but not in vehicle-treated mice (88 +/- 3 mmHg) nor eNOS null mice (104 +/- 3 mmHg). In wild-type mice, maximal vasorelaxation of mesenteric arteries to acetylcholine was not altered by chronic L-NAME or induction of diabetes but was reduced by 42 +/- 6% in L-NAME-treated diabetic mice. Furthermore, the relative roles of NO and endothelium-derived hyperpolarizing factor (EDHF) in acetylcholine-induced vasorelaxation were altered; the EDHF component was enhanced by L-NAME and blunted by diabetes. These data suggest that NO protects against the development of hypertension during early-stage diabetes in mice, even in the absence of eNOS. Furthermore, in mesenteric arteries, diabetes is associated with reduced EDHF function, with an apparent compensatory increase in NO function. Thus, prior inhibition of NOS results in endothelial dysfunction in early diabetes, since the diabetes-induced reduction in EDHF function cannot be compensated by increases in NO production.
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Fitzgerald SM, Bashari H, Cox JA, Parkington HC, Evans RG. Contributions of endothelium-derived relaxing factors to control of hindlimb blood flow in the mouse in vivo. Am J Physiol Heart Circ Physiol 2007; 293:H1072-82. [PMID: 17468338 DOI: 10.1152/ajpheart.00072.2007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We determined the contributions of various endothelium-derived relaxing factors to control of basal vascular tone and endothelium-dependent vasodilation in the mouse hindlimb in vivo. Under anesthesia, catheters were placed in a carotid artery, jugular vein, and femoral artery (for local hindlimb circulation injections). Hindlimb blood flow (HBF) was measured by transit-time ultrasound flowmetry. N(omega)-nitro-L-arginine methyl ester (L-NAME, 50 mg/kg plus 10 mg x kg(-1) x h(-1)), to block nitric oxide (NO) production, altered basal hemodynamics, increasing mean arterial pressure (30 +/- 3%) and reducing HBF (-30 +/- 12%). Basal hemodynamics were not significantly altered by indomethacin (10 mg x kg(-1) x h(-1)), charybdotoxin (ChTx, 3 x 10(-8) mol/l), apamin (2.5 x 10(-7) mol/l), or ChTx plus apamin (to block endothelium-derived hyperpolarizing factor; EDHF). Hyperemic responses to local injection of acetylcholine (2.4 microg/kg) were reproducible in vehicle-treated mice and were not significantly attenuated by L-NAME alone, indomethacin alone, L-NAME plus indomethacin with or without co-infusion of diethlyamine NONOate to restore resting NO levels, ChTx alone, or apamin alone. Hyperemic responses evoked by acetylcholine were reduced by 29 +/- 11% after combined treatment with apamin plus charybdotoxin, and the remainder was virtually abolished by additional treatment with L-NAME but not indomethacin. None of the treatments altered the hyperemic response to sodium nitroprusside (5 microg/kg). We conclude that endothelium-dependent vasodilation in the mouse hindlimb in vivo is mediated by both NO and EDHF. EDHF can fully compensate for the loss of NO, but this cannot be explained by tonic inhibition of EDHF by NO. Control of basal vasodilator tone in the mouse hindlimb is dominated by NO.
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Affiliation(s)
- Sharyn M Fitzgerald
- Department of Physiology, Monash University, Melbourne, Victoria 3800, Australia
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31
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Ceroni L, Ellis A, Wiehler WB, Jiang YF, Ding H, Triggle CR. Calcium-activated potassium channel and connexin expression in small mesenteric arteries from eNOS-deficient (eNOS-/-) and eNOS-expressing (eNOS+/+) mice. Eur J Pharmacol 2007; 560:193-200. [PMID: 17300779 DOI: 10.1016/j.ejphar.2007.01.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2006] [Revised: 12/14/2006] [Accepted: 01/08/2007] [Indexed: 11/20/2022]
Abstract
Endothelium-derived hyperpolarizing factor (EDHF), notably in the microcirculation, plays an important role in the regulation of vascular tone. The cellular events that mediate EDHF are critically dependent, in a vessel dependent manner, on small conductance calcium-activated potassium channels (SK) and intermediate conductance calcium-activated potassium channels (IK) as well as the presence of the gap junction connexins 37, 40, and 43. We hypothesized that the expression levels of SK, IK, as well as vascular connexins, notably 37, 40 and 43 but, potentially, connexin 45, would show correlation with the contribution of EDHF to acetylcholine-mediated vasodilatation as well as, in the absence of endothelial-derived NO, higher expression levels in eNOS(-/-) mice. Wire myograph studies were performed to confirm the contribution of EDHF to endothelium-dependent relaxation in 1st, 2nd and 3rd order small mesenteric arteries from C57BL/6J eNOS-expressing (eNOS(+/+)) and eNOS-deficient C57BL/6J (eNOS(-/-)) mice. Small mesenteric arteries, as well as the branch points between 1st and 2nd and 2nd and 3rd order vessels, were analysed for the expression of mRNA for SK1, SK2, SK3, IK and large conductance calcium-activated potassium channels (BK) and comparable studies were performed for connexins 37, 40, 43 and 45. Although the contribution of EDHF to endothelium-dependent relaxation was significantly greater in the 3rd order vessels from the eNOS(+/+) the real-time (RT) polymerase chain reaction (PCR) data showed no differences for the expression levels of mRNA for any of the channel subtypes or the connexins within the small mesenteric arteries from either the eNOS(+/+) or eNOS(-/-) mice, nor, based on RT PCR analysis, were there differences in expression of the potassium channels studied in the branch points versus 1st, 2nd or 3rd order vessels. These data suggest that neither the gene expression of calcium-activated potassium channels nor vascular connexins are modulated by NO; however, their functional contribution to endothelium-dependent relaxation may be modulated by other physiological parameters.
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Affiliation(s)
- Lisa Ceroni
- Smooth Muscle Research Group, Faculty of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, Alberta, Canada T2N 4N1
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Adlam D, Bendall JK, De Bono JP, Alp NJ, Khoo J, Nicoli T, Yokoyama M, Kawashima S, Channon KM. Relationships between nitric oxide-mediated endothelial function, eNOS coupling and blood pressure revealed by eNOS-GTP cyclohydrolase 1 double transgenic mice. Exp Physiol 2007; 92:119-26. [PMID: 17012144 DOI: 10.1113/expphysiol.2006.035113] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Endothelium-dependent relaxation in conduit vessels is mediated largely by nitric oxide (NO), produced by the enzyme endothelial nitric oxide synthase (eNOS) in the presence of the cofactor tetrahydrobiopterin (BH4) and mediated through a cGMP-dependent downstream signalling cascade. Endothelial NOS regulates blood pressure in vivo, and impaired endothelial NO bioactivity in vascular disease states may contribute to systemic hypertension. In the absence of sufficient levels of the cofactor BH4, NO becomes uncoupled from arginine oxidation and eNOS produces superoxide rather than NO. The enzymatic uncoupling of eNOS is an important feature of vascular disease states associated with increased oxidative stress. However, whether eNOS coupling, rather than overall eNOS activity, has specific effects on endothelium-dependent vasorelaxation in vitro, or on blood pressure regulation in vivo, remains unclear. In this study, we evaluate the relationships between blood pressure and endothelial function in models of eNOS uncoupling, using mice with endothelium-targeted transgenic eNOS overexpression (eNOS-Tg), in comparison with littermates in which eNOS coupling was rescued by additional endothelium-targeted overexpression of GTP cyclohydrolase 1 (eNOS/GCH-Tg) to increase endothelial BH4 levels. Despite the previously characterized differences in eNOS-dependent superoxide production between these animals, we find that blood pressure is equally reduced in both genotypes, compared with wild-type animals. Furthermore, both eNOS-Tg and eNOS/GCH-Tg mice exhibit similarly impaired endothelium-dependent vasorelaxation. We show that reduced vasorelaxation responses result from desensitization of cGMP-mediated signalling and are associated with increased NO production rather than changes in superoxide production.
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Affiliation(s)
- D Adlam
- Department of Cardiovascular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, OX3 8DU, UK
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Pannirselvam M, Ding H, Anderson TJ, Triggle CR. Pharmacological characteristics of endothelium-derived hyperpolarizing factor-mediated relaxation of small mesenteric arteries from db/db mice. Eur J Pharmacol 2006; 551:98-107. [PMID: 17027963 DOI: 10.1016/j.ejphar.2006.08.086] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2006] [Revised: 08/29/2006] [Accepted: 08/31/2006] [Indexed: 11/21/2022]
Abstract
Endothelial dysfunction is considered as a major risk factor of cardiovascular complications of type I and type II diabetes. Our previous studies have demonstrated that endothelial dysfunction in the small mesenteric arteries from 12-16 week old type II diabetic mice was associated with decreased bio-availability of nitric oxide whereas endothelium-derived hyperpolarizing factor (EDHF)-mediated relaxation was preserved. The objective of the present study was to characterize EDHF-mediated relaxations of small mesenteric arteries from db/db mice. A depolarizing concentration of KCl or tetraethylammonium (TEA, 10 mM) significantly inhibited the EDHF-mediated relaxation to acetylcholine and bradykinin in small mesenteric arteries from both db/+ and db/db mice. Charybdotoxin or iberiotoxin alone and a combination of ouabain and barium significantly reduced the maximal relaxation to acetylcholine in small mesenteric arteries from db/db mice and charybdotoxin or iberiotoxin either alone or in combination with apamin reduced the sensitivity to the EDHF-mediated component of the relaxation response to bradykinin. 17-octadecynoic acid, but not catalase, significantly reduced the sensitivity to EDHF-mediated responses to bradykinin in db/db mice; 17-octadecynoic acid had no effect on acetylcholine-mediated relaxations. No differences were, however, detected for mRNA expression levels of calcium-activated potassium channels or connexins 37, 40, 43 and 45. Collectively, these data suggest that bradykinin-induced, EDHF-dependent relaxation in small mesenteric arteries from db/db mice is mediated via cytochrome P450 product that activates the large conductance calcium-activated potassium (BK(Ca) or Slo) channel, whereas the acetylcholine-induced, EDHF-mediated relaxation involves neither cytochrome P450 product nor hydrogen peroxide.
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Affiliation(s)
- Malarvannan Pannirselvam
- The Heart and Stroke/Richard Lewar Center of Excellence in Cardiovascular Research, University of Toronto, Canada
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Félétou M, Vanhoutte PM. Endothelial dysfunction: a multifaceted disorder (The Wiggers Award Lecture). Am J Physiol Heart Circ Physiol 2006; 291:H985-1002. [PMID: 16632549 DOI: 10.1152/ajpheart.00292.2006] [Citation(s) in RCA: 539] [Impact Index Per Article: 29.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Endothelial cells synthesize and release various factors that regulate angiogenesis, inflammatory responses, hemostasis, as well as vascular tone and permeability. Endothelial dysfunction has been associated with a number of pathophysiological processes. Oxidative stress appears to be a common denominator underlying endothelial dysfunction in cardiovascular diseases. However, depending on the pathology, the vascular bed studied, the stimulant, and additional factors such as age, sex, salt intake, cholesterolemia, glycemia, and hyperhomocysteinemia, the mechanisms underlying the endothelial dysfunction can be markedly different. A reduced bioavailability of nitric oxide (NO), an alteration in the production of prostanoids, including prostacyclin, thromboxane A2, and/or isoprostanes, an impairment of endothelium-dependent hyperpolarization, as well as an increased release of endothelin-1, can individually or in association contribute to endothelial dysfunction. Therapeutic interventions do not necessarily restore a proper endothelial function and, when they do, may improve only part of these variables.
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Affiliation(s)
- Michel Félétou
- Department of Angiology, Institut de Recherches Servier, Suresnes, France
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Shi Y, Ku DD, Man RYK, Vanhoutte PM. Augmented Endothelium-Derived Hyperpolarizing Factor-Mediated Relaxations Attenuate Endothelial Dysfunction in Femoral and Mesenteric, but Not in Carotid Arteries from Type I Diabetic Rats. J Pharmacol Exp Ther 2006; 318:276-81. [PMID: 16565165 DOI: 10.1124/jpet.105.099739] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Individual vascular beds exhibit differences in vascular reactivity. The present study investigates the effects of streptozotocin-induced type I diabetes on endothelium-dependent responses of rat carotid, femoral, and mesenteric arteries. Rings with and without endothelium, suspended in organ chambers for isometric tension recording, were contracted with phenylephrine and exposed to increasing concentrations of acetylcholine. In carotid and femoral arteries, acetylcholine produced concentration- and endothelium-dependent relaxations that were abolished by Nomega-nitro-L-arginine methyl ester (L-NAME; specific nitric-oxide synthase inhibitor) and were impaired slightly in preparations from streptozotocin-treated rats (STZ-rats). This impairment could be prevented by L-arginine. In femoral arteries incubated with L-NAME, acetylcholine caused endothelium-dependent contractions that were abolished by 3-[(6-amino-(4-chlorobenzensulfonyl)-2-methyl-5,6,7,8-tetrahydronapht]-1-yl) propionic acid (S18886) (antagonist of thromboxane A2/prostaglandins H2-receptors) and reversed to relaxation by indomethacin (inhibitor of cyclooxygenase). The latter relaxation was inhibited by charybdotoxin plus apamin, suggesting a role of endothelium-dependent hyperpolarizing factor (EDHF). This EDHF-mediated component was augmented slightly in arteries from STZ-rats. In mesenteric arteries, relaxations to acetylcholine were only partially inhibited by L-NAME, and the L-NAME-resistant component was abolished by charybdotoxin plus apamin. In the mesenteric arteries from STZ-rats, L-NAME-sensitive relaxations to acetylcholine were reduced and the EDHF-component was augmented. These findings demonstrate a marked heterogeneity in endothelium-dependent responses in rat arteries and their differential adaptation in the course of type I diabetes. In particular, the EDHF-mediated component not only compensates for the reduced bioavailability of nitric oxide in the femoral and mesenteric artery but also counteracts the augmented endothelium-dependent contractions in the former.
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Affiliation(s)
- Yi Shi
- Department of Pharmacology, 2/F, Laboratory Block, Faculty of Medicine Bldg. 21, Sassoon Rd., Pokfulam, University of Hong Kong, Hong Kong, China
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36
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Abstract
The endothelium controls vascular tone not only by releasing nitric oxide (NO) and prostacyclin but also by other pathways causing hyperpolarization of the underlying smooth muscle cells. This characteristic was at the origin of the denomination endothelium-derived hyperpolarizing factor (EDHF). We know now that this acronym includes different mechanisms. In general, EDHF-mediated responses involve an increase in the intracellular calcium concentration, the opening of calcium-activated potassium channels of small and intermediate conductance and the hyperpolarization of the endothelial cells. This results in an endothelium-dependent hyperpolarization of the smooth muscle cells, which can be evoked by direct electrical coupling through myo-endothelial junctions and/or the accumulation of potassium ions in the intercellular space. Potassium ions hyperpolarize the smooth muscle cells by activating inward rectifying potassium channels and/or Na+/K(+)-ATPase. In some blood vessels, including large and small coronary arteries, the endothelium releases arachidonic acid metabolites derived from cytochrome P450 monooxygenases. The epoxyeicosatrienoic acids (EET) generated are not only intracellular messengers but also can diffuse and hyperpolarize the smooth muscle cells by activating large conductance calcium-activated potassium channels. Additionally, the endothelium can produce other factors such as lipoxygenases derivatives or hydrogen peroxide (H2O2). These different mechanisms are not necessarily exclusive and can occur simultaneously.
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Affiliation(s)
- Michel Félétou
- Department of Angiology, Institut de Recherches Servier, Suresnes, France
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Triggle CR, Howarth A, Cheng ZJ, Ding H. Twenty-five years since the discovery of endothelium-derived relaxing factor (EDRF): does a dysfunctional endothelium contribute to the development of type 2 diabetes? Can J Physiol Pharmacol 2006; 83:681-700. [PMID: 16333371 DOI: 10.1139/y05-069] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Twenty-five years ago, the discovery of endothelium-derived relaxing factor opened a door that revealed a new and exciting role for the endothelium in the regulation of blood flow and led to the discovery that nitric oxide (NO) multi-tasked as a novel cell-signalling molecule. During the next 25 years, our understanding of both the importance of the endothelium as well as NO has greatly expanded. No longer simply a barrier between the blood and vascular smooth muscle, the endothelium is now recognized as a complex tissue with heterogeneous properties. The endothelium is the source of not only NO but also numerous vasoactive molecules and signalling pathways, some of which are still not fully characterized such as the putative endothelium-derived relaxing factor. Dysfunction of the endothelium is a key risk factor for the development of macro- and microvascular disease and, by coincidence, the discovery that NO was generated in the endothelium corresponds approximately in time with the increased incidence of type 2 diabetes. Primarily linked to dietary and lifestyle changes, we are now facing a global pandemic of type 2 diabetes. Characterized by insulin resistance and hyperglycaemia, type 2 diabetes is increasingly being diagnosed in adolescents as well as children. Is there a link between dietary-related hyperglycaemic insults to the endothelium, blood flow changes, and the development of insulin resistance? This review explores the evidence for and against this hypothesis.
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Affiliation(s)
- Chris R Triggle
- School of Medical Sciences, Bundoora West Campus, RMIT University, Victoria, Australia
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Abstract
The vascular endothelium synthesises the vasodilator and anti-aggregatory mediator nitric oxide (NO) from L-arginine. This action is catalysed by the action of NO synthases, of which two forms are present in the endothelium. Endothelial (e)NOS is highly regulated, constitutively active and generates NO in response to shear stress and other physiological stimuli. Inducible (i)NOS is expressed in response to immunological stimuli, is transcriptionally regulated and, once activated, generates large amounts of NO that contribute to pathological conditions. The physiological actions of NO include the regulation of vascular tone and blood pressure, prevention of platelet aggregation and inhibition of vascular smooth muscle proliferation. Many of these actions are a result of the activation by NO of the soluble guanylate cyclase and consequent generation of cyclic guanosine monophosphate (cGMP). An additional target of NO is the cytochrome c oxidase, the terminal enzyme in the electron transport chain, which is inhibited by NO in a manner that is reversible and competitive with oxygen. The consequent reduction of cytochrome c oxidase leads to the release of superoxide anion. This may be an NO-regulated cell signalling system which, under certain circumstances, may lead to the formation of the powerful oxidant species, peroxynitrite, that is associated with a variety of vascular diseases.
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Affiliation(s)
- S Moncada
- The Wolfson Institute for Biomedical Research, University College London, Gower Street, London WC1E 6BT, UK.
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Ding H, Hashem M, Wiehler WB, Lau W, Martin J, Reid J, Triggle C. Endothelial dysfunction in the streptozotocin-induced diabetic apoE-deficient mouse. Br J Pharmacol 2005; 146:1110-8. [PMID: 16231005 PMCID: PMC1751246 DOI: 10.1038/sj.bjp.0706417] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2005] [Revised: 09/01/2005] [Accepted: 09/07/2005] [Indexed: 11/08/2022] Open
Abstract
Endothelial dysfunction plays a role in the development of atherosclerosis and diabetes-associated vascular disease and, in the streptozotocin (STZ)-induced apoE-deficient diabetic mouse, we report that, when compared to the citrate (CIT)-treated nondiabetic apoE-deficient control, acetylcholine (Ach)-mediated endothelium-dependent relaxation was reduced in the small mesenteric arteries (SMA) and the plaque-prone regions of the aorta from the STZ-diabetic mouse. In the SMA the component of Ach-mediated relaxation that was attributed to nitric oxide (NO) from STZ-treated diabetic apoE-deficient mice was enhanced; however, the endothelium-derived hyperpolarizing factor (EDHF)-mediated component was reduced. The EDHF component was assessed by determining the component of the Ach-mediated response that was resistant to the combination of the NO synthase (NOS) inhibitor Nomega-nitro-L-arginine methyl ester, cyclooxygenase inhibitor, indomethacin, and soluble guanylate cyclase inhibitor, ODQ, and inhibited by the combination of the intermediate conductance KCa (IKCa) inhibitor TRAM-34 and the small-conductance KCa (SKCa) inhibitor apamin. Endothelial NOS was increased but SK2, SK3 and connexin (Cx) 37 mRNA expressions were significantly (P<0.05) decreased in the SMA from STZ-treated apoE-deficient mice compared to the CIT-treated controls. There was no difference in the IKCa expression or in Cx 40, 43 and 45 mRNA levels between STZ- and CIT-treated mice. The microvasculature of STZ-induced apoE-deficient mice developed endothelial dysfunction, which may be linked to a decrease in the contribution of the EDHF component due to a decrease in SK2 and 3 and Cx 37 expression.
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Affiliation(s)
- Hong Ding
- School of Medical Sciences, RMIT University, Bundoora West Campus, Bundoora, Victoria 3083, Australia.
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40
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McGuire JJ, Hollenberg MD, Bennett BM, Triggle CR. Hyperpolarization of murine small caliber mesenteric arteries by activation of endothelial proteinase-activated receptor 2. Can J Physiol Pharmacol 2005; 82:1103-12. [PMID: 15644953 DOI: 10.1139/y04-121] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Activation of endothelial proteinase-activated receptor 2 (PAR-2) relaxes vascular smooth muscle (VSM) and causes hypotension by nitric oxide (NO)-prostanoid-dependent and -independent mechanisms. We investigated whether endothelium-dependent hyperpolarization of VSM was the mechanism whereby resistance caliber arteries vasodilated independently of NO. VSM membrane potentials and isometric tension were measured concurrently to correlate the electrophysiological and mechanical changes in murine small caliber mesenteric arteries. In uncontracted arteries, the PAR-2 agonist, SLIGRL-NH2 (0.1 to 10 micromol/L), hyperpolarized the VSM membrane potential only in endothelium-intact arterial preparations. This response was unaltered by treatment of arteries with inhibitors of NO synthases (L-NAME), soluble guanylyl cyclase (ODQ), and cyclooxygenases (indomethacin). L-NAME, ODQ, and indomethacin also failed to inhibit SLIGRL-NH2-induced hyperpolarization and of cirazoline-contracted mesenteric arteries. However, in blood vessels that were depolarized and contracted with 30 mmol/L KCl, the effects of the SLIGRL-NH2 on membrane potential and tension were not observed. SLIGRL-NH2-induced hyperpolarization and relaxation was inhibited completely by the combination of apamin plus charybdotoxin, but only partially inhibited after treatment with the combination of barium plus ouabain, suggesting an important role for SKCa and IKCa channels and a lesser role for Kir channels and Na+/K+ ATPases in the hyperpolarization response. We concluded that activation of endothelial PAR-2 hyperpolarized the vascular smooth muscle (VSM) cells of small caliber arteries, without requiring the activation of NO synthases, cyclooxygenases, or soluble guanylyl cyclase. Indeed, this hyperpolarization may be a primary mechanism for PAR-2-induced hypotension in vivo.
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Affiliation(s)
- John J McGuire
- Smooth Muscle Research Group, Canadiian Institutes of Health Research Group on the Regulation of Vascular Contractility, Department of Pharmacology, Faculty of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada.
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Adlam D, Azeem T, Ali T, Gershlick A. Is there a role for provocation testing to diagnose coronary artery spasm? Int J Cardiol 2005; 102:1-7. [PMID: 15939093 DOI: 10.1016/j.ijcard.2004.07.016] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2004] [Accepted: 07/23/2004] [Indexed: 10/25/2022]
Abstract
Spontaneous coronary artery spasm is an important cause of morbidity both in patients with coronary artery disease and in those with variant angina. A number of pharmacological agents have been identified which can provoke coronary artery spasm in susceptible patients. The role of provocation testing in the clinical diagnosis of coronary spasm is controversial. This is reflected by variations in the clinical use of provocation testing between specialist cardiac centres. Provocation testing appears to be a sensitive method of identifying patients with variant angina and active disease but such patients can often be diagnosed clinically. The specificity is less clear. There is little evidence that altering patient therapy on the basis of a positive test modifies prognosis. There may be a role for provocation testing in rare patients with refractory disease to identify a target site for coronary stenting. A more widespread use of these tests in patients with undiagnosed chest pain syndromes would not currently be recommended.
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Affiliation(s)
- David Adlam
- Department of Cardiology, Glenfield Hospital, Groby Road, Leicester LE3 9QP, England.
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Fitzgerald SM, Kemp-Harper BK, Tare M, Parkington HC. ROLE OF ENDOTHELIUM-DERIVED HYPERPOLARIZING FACTOR IN ENDOTHELIAL DYSFUNCTION DURING DIABETES. Clin Exp Pharmacol Physiol 2005; 32:482-7. [PMID: 15854163 DOI: 10.1111/j.1440-1681.2005.04216.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
1. Under normal conditions, the endothelium plays a major role in the maintenance of vasodilatory tone via the production of endothelium-derived vasodilator agents, such as prostacyclin, nitric oxide and endothelium-derived hyperpolarizing factor (EDHF). Inhibition of endothelium-dependent relaxation features prominently in a range of cardiovascular diseases, including hypertension, coronary artery disease and diabetes. 2. Endothelium-derived hyperpolarizing factor is a prominent vasodilator, particularly in smaller arteries and arterioles. There is now emerging evidence to suggest that EDHF may play a role in the endothelial dysfunction in diabetes. 3. Since the first description of endothelium-dependent hyperpolarization some 20 years ago, it has emerged that EDHF is heterogeneous in nature, consisting of diffusible factors and contact-mediated mechanisms. The specific identity of EDHF in any particular vascular bed may influence the impact of diabetes on vascular function. 4. There is accumulating evidence in diabetic rat models and humans showing impaired EDHF activity in small resistance vessels. In contrast, studies in mice suggest that EDHF activity is actually enhanced under diabetic conditions. 5. It is clear that alterations in EDHF activity may have an important contribution in diabetes, more specifically in contributing to microvascular complications observed under diabetic conditions.
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Affiliation(s)
- Sharyn M Fitzgerald
- Department of Physiology, Monash University, Melbourne, Victoria, Australia.
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Ding H, Triggle CR. Endothelial cell dysfunction and the vascular complications associated with type 2 diabetes: assessing the health of the endothelium. Vasc Health Risk Manag 2005; 1:55-71. [PMID: 17319098 PMCID: PMC1993929 DOI: 10.2147/vhrm.1.1.55.58939] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Diabetes-associated vascular complications are collectively the major clinical problems facing patients with diabetes and lead to the considerably higher mortality rate than that of the general population. People with diabetes have a much higher incidence of coronary artery disease as well as peripheral vascular diseases in part because of accelerated atherogenesis. Despite the introduction of new therapies, it has not been possible to effectively reduce the high cardiovascular morbidity and mortality associated with diabetes. Of additional concern is the recognition by the World Health Organization that we are facing a global epidemic of type 2 diabetes. Endothelial dysfunction is an early indicator of cardiovascular disease, including that seen in type 2 diabetes. A healthy endothelium, as defined in terms of the vasodilator/blood flow response to an endothelium-dependent vasodilator, is an important indicator of cardiovascular health and, therefore, a goal for corrective interventions. In this review we explore the cellular basis for endothelial dysfunction in an attempt to identify appropriate new targets and strategies for the treatment of diabetes. In addition, we consider the question of biomarkers for vascular disease and evaluate their usefulness for the early detection of and their role as contributors to vascular dysfunction.
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Affiliation(s)
- Hong Ding
- School of Medical Sciences, RMIT University, BundooraWest Campus, Bundoora,VIC, Australia
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Ozawa Y, Hayashi K, Kanda T, Homma K, Takamatsu I, Tatematsu S, Yoshioka K, Kumagai H, Wakino S, Saruta T. Impaired nitric oxide- and endothelium-derived hyperpolarizing factor-dependent dilation of renal afferent arteriole in Dahl salt-sensitive rats. Nephrology (Carlton) 2004; 9:272-7. [PMID: 15504139 DOI: 10.1111/j.1440-1797.2004.00292.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND AND AIMS We previously demonstrated that acetylcholine elicited nitric oxide-dependent sustained and endothelium-derived hyperpolarizing factor (EDHF)-dependent transient dilation of afferent arterioles. The present study examined whether free radicals interacted with nitric oxide-dependent and EDHF-dependent vasodilator mechanisms in renal microvessels of salt-sensitive hypertension, using the isolated perfused hydronephrotic kidney. METHODS AND RESULTS Following the pretreatment with indomethacin (100 micromol/L) with or without nitro- l-arginine methylester (100 micromol/L), the effect of acetylcholine on noradrenaline (0.3 micromol/L)-induced constriction was evaluated in kidneys from Dahl salt-sensitive and salt-resistant rats. Although acetylcholine (0.01-10 micromol/L) caused dose-dependent and sustained vasodilation of afferent arterioles, attenuated dilation was observed in Dahl salt-sensitive rats, compared with that in salt-resistant rats (58 +/- 4 vs 101 +/- 11% reversal at 10 micromol/L acetylcholine). In the presence of nitro- l-arginine methylester, acetylcholine elicited only transient dilation, with vasodilator response blunted in Dahl salt-sensitive rats (64 +/- 4 vs 100 +/- 9% reversal at 10 micromol/L acetylcholine). Furthermore, chronic (8-10 weeks) treatment with tempol caused partial restoration of acetylcholine (10 micromol/L)-induced sustained arteriolar dilation (71 +/- 3% reversal), but complete reversal of transient dilation (92 +/- 4% reversal). Finally, acute treatment with tempol not only improved the sustained component of the acetylcholine-induced dilation but also restored the impaired responsiveness of transient dilation in Dahl salt-sensitive rats. CONCLUSION Both sustained (nitric oxide-mediated) and transient (EDHF-mediated) components of acetylcholine-induced afferent arteriolar dilation were attenuated in Dahl salt-sensitive rats, which was attributed, in part, to enhanced free radical activity. A reversal of the sustained and transient vasodilation by the acute tempol treatment suggests possible interaction between free radicals and EDHF as well as increased bioavailability of nitric oxide.
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Affiliation(s)
- Yuri Ozawa
- Department of Internal Medicine, School of Medicine, Keio University, Tokyo, Japan
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Ellis A, Triggle CR. Endothelium-derived reactive oxygen species: their relationship to endothelium-dependent hyperpolarization and vascular tone. Can J Physiol Pharmacol 2004; 81:1013-28. [PMID: 14719036 DOI: 10.1139/y03-106] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Opinions on the role of reactive oxygen species (ROS) in the vasculature have shifted in recent years, such that they are no longer merely regarded as indicators of cellular damage or byproducts of metabolism--they may also be putative mediators of physiological functions. Hydrogen peroxide (H2O2), in particular, can initiate vascular myocyte proliferation (and, incongruously, apoptosis), hyperplasia, cell adhesion, migration, and the regulation of smooth muscle tone. Endothelial cells express enzymes that produce ROS in response to various stimuli, and H2O2 is a potent relaxant of vascular smooth muscle. H2O2 itself can mediate endothelium-dependent relaxations in some vascular beds. Although nitric oxide (NO) is well recognized as an endothelium-derived dilator, it is also well established, particularly in the microvasculature, that another factor, endothelium-derived hyperpolarizing factor (EDHF), is a significant determinant of vasodilatory tone. This review primarily focuses on the hypothesis that H2O2 is an EDHF in resistance arteries. Putative endothelial sources of H2O2 and the effects of H2O2 on potassium channels, calcium homeostasis, and vascular smooth muscle tone are discussed. Furthermore, given the perception that ROS can more likely elicit cytotoxic effects than perform signalling functions, the arguments for and against H2O2 being an endogenous vasodilator are assessed.
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Affiliation(s)
- Anthie Ellis
- Smooth Muscle Research Group, Faculty of Medicine, University of Calgary, AB, Canada
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De Clerck I, Boussery K, Pannier JL, Van De Voorde J. Potassium Potently Relaxes Small Rat Skeletal Muscle Arteries. Med Sci Sports Exerc 2003; 35:2005-12. [PMID: 14652495 DOI: 10.1249/01.mss.0000099101.39139.fa] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
INTRODUCTION Skeletal muscle contraction elicits an explosive rise in interstitial potassium (K+) concentration. K+ has been considered as one of the most potent vasoactive metabolites in skeletal muscle arterioles. Studies on isolated blood vessels report large relaxations when extracellular [K+] is increased up to 10 mM. We studied the effects of smaller and physiologically more relevant increases in [K+] (adding 1, 2, and 3 mM) and compared them with relaxations induced by the endothelium derived hyperpolarizing factor (EDHF). METHODS Rat gluteal arteries were isolated and mounted in an organ bath for isometric tension recording. After precontraction with norepinephrine, acetylcholine or K+ was added in control conditions, after removal of the endothelium or in the presence of ouabain or Ba2+. RESULTS Application of 1, 2, or 3 mM K+ induced large vasodilations (up to 75.4% with 3 mM) (N = 40), which were more sustained at the higher concentrations. Removal of the vascular endothelium had no effect on this relaxation. Inhibition of the Kir channels with Ba2+ did not alter the K+-induced relaxations, although it significantly inhibited the EDHF-mediated relaxation. Incubation with ouabain significantly decreased the K+- and EDHF-induced relaxation. Simultaneous application of Ba2+ and ouabain totally abolished both K+- and EDHF-induced responses. CONCLUSION Even small increases in extracellular K+ concentration elicit large endothelium-independent and ouabain-sensitive relaxations in small skeletal muscle arteries. The fact that both K+- and EDHF-induced vasorelaxations show similar characteristics indicates that K+ might be the EDHF in this type of artery.
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Affiliation(s)
- Ine De Clerck
- Department of Movement and Sports Sciences, Ghent University, Belgium
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McGuire JJ, Triggle CR. Searching for the physiological role and therapeutic potential of vascular proteinase-activated receptor-2 (PAR2). Drug Dev Res 2003. [DOI: 10.1002/ddr.10314] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Chan SL, Fiscus RR. Vasorelaxations induced by calcitonin gene-related peptide, vasoactive intestinal peptide, and acetylcholine in aortic rings of endothelial and inducible nitric oxide synthase-knockout mice. J Cardiovasc Pharmacol 2003; 41:434-43. [PMID: 12605022 DOI: 10.1097/00005344-200303000-00012] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The objective of this study was to determine if vasorelaxant responses to calcitonin gene-related peptide (CGRP), vasoactive intestinal peptide (VIP), and acetylcholine are altered in aortic rings of mice lacking genetic expression of endothelial nitric oxide synthase (eNOS) or inducible nitric oxide synthase (iNOS) genes (i.e., eNOS- and iNOS-knockout mice) as compared with control (wild-type) mice. Aortic rings from eNOS-knockout (eNOS (-/-)) mice did not relax in response to acetylcholine, thereby confirming previous reports. Aortic rings from iNOS-knockout (iNOS (-/-)) mice relaxed in response to acetylcholine in an endothelium-dependent manner. However, maximum relaxations in endothelium-intact rings were significantly (p < 0.05) larger than in control mice (85.3 +/- 3.1% in iNOS (-/-) mice vs. 67.9 +/- 5.6% in controls). CGRP caused concentration-dependent relaxations in aortas of all three types of mice: control mice, iNOS (-/-) mice, and eNOS (-/-) mice. Vasorelaxant responses to CGRP in control and iNOS (-/-) mice had identical relationships; both were partially dependent on endothelium. In eNOS (-/-) mice, dose-response curves of CGRP in endothelium-intact and endothelium-denuded rings were not significantly different, indicating loss of the partial dependence on endothelium. The vasorelaxant responses to VIP were completely dependent on endothelium in control and iNOS (-/-) mice. Maximum relaxations to VIP in iNOS (-/-) mice (77.4 +/- 2.7%) were significantly greater than in control mice (64.0 +/- 5.5%). Vasorelaxant responses to VIP in eNOS (-/-) aortic rings were also endothelium-dependent, but responses were greatly attenuated compared with wild-type mice. Relaxations induced by VIP (1 x 10 ) in endothelium-intact aortic rings of eNOS (-/-) mice and control mice were 18.3 +/- 5.4% and 64.0 +/- 5.5%, respectively. These findings demonstrated that, in eNOS (-/-) mice, aortic vasorelaxant responses to CGRP were fully present but no longer dependent on the endothelium, and responses to VIP were greatly attenuated compared with control and responses to acetylcholine were abolished. In iNOS (-/-) mice, aortic vasorelaxant responses to VIP and acetylcholine were significantly greater than wild-type control, suggesting that induction of iNOS may have attenuated vascular responses to VIP and acetylcholine in wild-type controls.
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Affiliation(s)
- Siu L Chan
- Department of Physiology, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong
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Ortiz PA, Garvin JL. Cardiovascular and renal control in NOS-deficient mouse models. Am J Physiol Regul Integr Comp Physiol 2003; 284:R628-38. [PMID: 12571071 DOI: 10.1152/ajpregu.00401.2002] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Nitric oxide (NO) plays an essential role in the maintenance of cardiovascular and renal homeostasis. Endogenous NO is produced by three different NO synthase (NOS) isoforms: endothelial NOS (eNOS), inducible NOS (iNOS), and neuronal NOS (nNOS). To investigate which NOS is responsible for NO production in different tissues, NOS knockout (-/-) mice have been generated for the three isoforms. This review focuses on the regulation of cardiovascular and renal function in relation to blood pressure homeostasis in the different NOS-/- mice. Although regulation of vascular tone and cardiac function in eNOS-/- has been extensively studied, far less is known about renal function in these mice. eNOS-/- mice are hypertensive, but the mechanism responsible for their high blood pressure is still not clear. Less is known about cardiovascular and renal control in nNOS-/- mice, probably because their blood pressure is normal. Recent data suggest that nNOS plays important roles in cardiac function, renal homeostasis, and regulation of vascular tone under certain conditions, but these are only now beginning to be studied. Inasmuch as iNOS is absent from the cardiovascular system under physiological conditions, it may become important to blood pressure regulation only during pathological conditions related to inflammatory processes. However, iNOS is constitutively expressed in the kidney, where its function is largely unknown. Overall, the study of NOS knockout mice has been very useful and produced many answers, but it has also raised new questions. The appearance of compensatory mechanisms suggests the importance of the different isoforms to specific processes, but it also complicates interpretation of the data. In addition, deletion of a single gene may have physiologically significant effects in addition to those being studied. Thus the presence or absence of a specific phenotype may not reflect the most important physiological function of the absent gene.
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Affiliation(s)
- Pablo A Ortiz
- Division of Hypertension and Vascular Research, Department of Internal Medicine, Henry Ford Hospital, Detroit, Michigan 48202, USA.
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Ding H, Triggle CR. Contribution of EDHF and the role of potassium channels in the regulation of vascular tone. Drug Dev Res 2003. [DOI: 10.1002/ddr.10135] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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