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Batista C, Cruz JVR, Stipursky J, de Almeida Mendes F, Pesquero JB. Kinin B 1 receptor and TLR4 interaction in inflammatory response. Inflamm Res 2024:10.1007/s00011-024-01909-1. [PMID: 38965133 DOI: 10.1007/s00011-024-01909-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2024] [Revised: 05/27/2024] [Accepted: 06/19/2024] [Indexed: 07/06/2024] Open
Abstract
OBJECTIVE We aimed to broaden our understanding of a potential interaction between B1R and TLR4, considering earlier studies suggesting that lipopolysaccharide (LPS) may trigger B1R stimulation. METHODS We assessed the impact of DBK and LPS on the membrane potential of thoracic aortas from C57BL/6, B1R, or TLR4 knockout mice. Additionally, we examined the staining patterns of these receptors in the thoracic aortas of C57BL/6 and in endothelial cells (HBMEC). RESULTS DBK does not affect the resting membrane potential of aortic rings in C57BL/6 mice, but it hyperpolarizes preparations in B1KO and TLR4KO mice. The hyperpolarization mechanism in B1KO mice involves B2R, and the TLR4KO response is independent of cytoplasmic calcium influx but relies on potassium channels. Conversely, LPS hyperpolarizes thoracic aorta rings in both C57BL/6 and B1KO mice, with the response unaffected by a B1R antagonist. Interestingly, the absence of B1R alters the LPS response to potassium channels. These activities are independent of nitric oxide synthase (NOS). While exposure to DBK and LPS does not alter B1R and TLR4 mRNA expression, treatment with these agonists increases B1R staining in endothelial cells of thoracic aortic rings and modifies the staining pattern of B1R and TLR4 in endothelial cells. Proximity ligation assay suggests a interaction between the receptors. CONCLUSION Our findings provide additional support for a putative connection between B1R and TLR4 signaling. Given the involvement of these receptors and their agonists in inflammation, it suggests that drugs and therapies targeting their effects could be promising therapeutic avenues worth exploring.
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Affiliation(s)
- Carolina Batista
- Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rua César Pernetta, S/N, Prédio do ICB (Anexo ao Bloco F do CCS), 3º andar, sala LJ.03.01, Cidade Universitária, Rio de Janeiro, RJ, CEP: 21941-902, Brazil
- Departamento de Biofísica, Universidade Federal de São Paulo, R. Pedro de Toledo, 669, 9° andar, São Paulo, SP, CEP: 04039-032, Brazil
| | - João Victor Roza Cruz
- Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rua César Pernetta, S/N, Prédio do ICB (Anexo ao Bloco F do CCS), 3º andar, sala LJ.03.01, Cidade Universitária, Rio de Janeiro, RJ, CEP: 21941-902, Brazil
| | - Joice Stipursky
- Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rua César Pernetta, S/N, Prédio do ICB (Anexo ao Bloco F do CCS), 3º andar, sala LJ.03.01, Cidade Universitária, Rio de Janeiro, RJ, CEP: 21941-902, Brazil
| | - Fabio de Almeida Mendes
- Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rua César Pernetta, S/N, Prédio do ICB (Anexo ao Bloco F do CCS), 3º andar, sala LJ.03.01, Cidade Universitária, Rio de Janeiro, RJ, CEP: 21941-902, Brazil.
| | - João Bosco Pesquero
- Departamento de Biofísica, Universidade Federal de São Paulo, R. Pedro de Toledo, 669, 9° andar, São Paulo, SP, CEP: 04039-032, Brazil.
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Lykke L, Ernst C, Bek T. The vasoactive effects of bradykinin, vasoactive intestinal peptide, calcitonin gene-related peptide and neuropeptide Y depend on the perivascular tissue in porcine retinal arterioles in vitro. Acta Ophthalmol 2024; 102:349-356. [PMID: 37565361 DOI: 10.1111/aos.15742] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2023] [Revised: 06/27/2023] [Accepted: 07/27/2023] [Indexed: 08/12/2023]
Abstract
PURPOSE The retina contains a number of vasoactive neuropeptides and corresponding receptors, but the role of these neuropeptides for tone regulation of retinal arterioles has not been studied in detail. METHODS Porcine arterioles with preserved perivascular retinal tissue were mounted in a wire myograph, and the tone was measured after the addition of increasing concentrations of bradykinin, vasoactive intestinal peptide (VIP), neuropeptide Y (NPY), substance P (SP), calcitonin gene-related peptide (CGRP) and brain natriuretic peptide (BNP). The experiments were performed during inhibition of the synthesis of nitric oxide (NO), prostaglandins and dopamine and were repeated after removal of the perivascular retinal tissue. RESULTS Bradykinin, VIP and CGRP induced significant concentration-dependent dilatation and NPY significant concentration-dependent contraction of the arterioles in the presence of perivascular retinal tissue (p < 0.03 for all comparisons) but not on isolated arterioles. BNP and SP had no effect on vascular tone. The NOS inhibitor L-NAME reduced bradykinin- and VIP-induced relaxation (p < 0.001 for both comparisons), whereas none of the other inhibitors influenced the vasoactive effects of the studied neuropeptides. CONCLUSION The effects of neuropeptides on the tone of retinal arterioles depend on the perivascular retinal tissue and may involve effects other than those mediated by nitric oxide, prostaglandins and adrenergic compounds. Investigation of the mechanisms underlying the vasoactive effect of neuropeptides may be important for understanding and treating retinal diseases where disturbances in retinal flow regulation are involved in the disease pathogenesis.
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Affiliation(s)
- Lise Lykke
- Department of Ophthalmology, Aarhus University Hospital, Aarhus N, Denmark
| | - Charlotte Ernst
- Department of Ophthalmology, Aarhus University Hospital, Aarhus N, Denmark
| | - Toke Bek
- Department of Ophthalmology, Aarhus University Hospital, Aarhus N, Denmark
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Ca 2+-Activated K + Channels and the Regulation of the Uteroplacental Circulation. Int J Mol Sci 2023; 24:ijms24021349. [PMID: 36674858 PMCID: PMC9867535 DOI: 10.3390/ijms24021349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 01/06/2023] [Accepted: 01/08/2023] [Indexed: 01/13/2023] Open
Abstract
Adequate uteroplacental blood supply is essential for the development and growth of the placenta and fetus during pregnancy. Aberrant uteroplacental perfusion is associated with pregnancy complications such as preeclampsia, fetal growth restriction (FGR), and gestational diabetes. The regulation of uteroplacental blood flow is thus vital to the well-being of the mother and fetus. Ca2+-activated K+ (KCa) channels of small, intermediate, and large conductance participate in setting and regulating the resting membrane potential of vascular smooth muscle cells (VSMCs) and endothelial cells (ECs) and play a critical role in controlling vascular tone and blood pressure. KCa channels are important mediators of estrogen/pregnancy-induced adaptive changes in the uteroplacental circulation. Activation of the channels hyperpolarizes uteroplacental VSMCs/ECs, leading to attenuated vascular tone, blunted vasopressor responses, and increased uteroplacental blood flow. However, the regulation of uteroplacental vascular function by KCa channels is compromised in pregnancy complications. This review intends to provide a comprehensive overview of roles of KCa channels in the regulation of the uteroplacental circulation under physiological and pathophysiological conditions.
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Mariacarmela G, Milena E, Sveinbjorn G, Daniel H, Maurizio M. Placental protein 13 dilation of pregnant rat uterine vein is endothelium dependent and involves nitric oxide/calcium activated potassium channels signals. Placenta 2022; 126:233-238. [PMID: 35872513 DOI: 10.1016/j.placenta.2022.07.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Revised: 07/01/2022] [Accepted: 07/03/2022] [Indexed: 12/19/2022]
Abstract
INTRODUCTION Accumulating evidence demonstrates the importance of the galectin protein Placental Protein 13 (PP13) in predicting Preeclampsia (PE), a gestational disorder that has no cure and is associated with a compromised uterine vascular adaptation to pregnancy. Uterine vasculature undergoes significant remodeling (growth in length and in circumference) during normal pregnancy to accommodate the increased blood volume to the feto-placental unit. The aim of this study was to demonstrate the role of PP13 on the uterine veins (UVs). METHODS PP13 was tested on UVs isolated from rat by using a pressurized myograph. The PP13 investigation was carried out in the presence of: a) nitric oxide synthases inhibitors (l-NAME + L-NNA, 2 x 10-4 M); b) small conductance Ca2+-activated K+ channels (SKca) inhibitor (Apamin, 10-7 M); c) intermediate conductance Ca2+-activated K+ channels (IKca) inhibitor (TRAM-34, 10-5 M); d) big conductance Ca2+-activated K+ channels (BKca) inhibitor (Paxilline, 10-5 M) and in the absence of endothelium. RESULTS Our results showed that in late pregnancy, PP13 induced a significant dilation of UVs that is endothelium dependent. Further, PP13-dilation is mediated by the SKca - NO - BKca pathway. DISCUSSION For the first time, this study provides evidence that in pregnancy, the UVs are dilated by PP13 and suggests SKCa as a potential target for treatments aimed at restoring pregnancy complication associated with deficiency in uterine adaptation.
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Affiliation(s)
- Gatto Mariacarmela
- Department of Biology, Ecology and Earth Sciences, University of Calabria, 87036, Rende, Italy
| | - Esposito Milena
- Department of Biology, Ecology and Earth Sciences, University of Calabria, 87036, Rende, Italy
| | - Gizurarson Sveinbjorn
- Faculty of Pharmaceutical Sciences, University of Iceland, Hofsvallagata 53, 107, Reykjavik, Iceland
| | - Henrion Daniel
- MitoVasc Institute, UMR CNRS 6015-INSERM U1083, University of Angers, France
| | - Mandalà Maurizio
- Department of Biology, Ecology and Earth Sciences, University of Calabria, 87036, Rende, Italy.
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Metabolic regulation and dysregulation of endothelial small conductance calcium activated potassium channels. Eur J Cell Biol 2022; 101:151208. [DOI: 10.1016/j.ejcb.2022.151208] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Revised: 02/06/2022] [Accepted: 02/07/2022] [Indexed: 12/13/2022] Open
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Xing H, Zhang Z, Shi G, He Y, Song Y, Liu Y, Harrington EO, Sellke FW, Feng J. Chronic Inhibition of mROS Protects Against Coronary Endothelial Dysfunction in Mice With Diabetes. Front Cell Dev Biol 2021; 9:643810. [PMID: 33681229 PMCID: PMC7930489 DOI: 10.3389/fcell.2021.643810] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 01/29/2021] [Indexed: 11/13/2022] Open
Abstract
Diabetes is associated with coronary endothelial dysfunction. Persistent oxidative stress during diabetes contributes to coronary endothelial dysfunction. The mitochondria are main sources of reactive oxygen species (ROS) in diabetes, and mitochondria-targeted antioxidant mito-Tempo can prevent mitochondrial reactive oxygen species (mROS) generation in a variety of disorders. Inhibition/inactivation of small-conductance Ca2+-activated K+ (SK) channels contribute to diabetic downregulation of coronary endothelial function/relaxation. However, few investigated the role of mROS on endothelial dysfunction/vasodilation and endothelial SK channel downregulation in diabetes. The aim of present study was to investigate the chronic administration of mito-Tempo, on coronary vasodilation, and endothelial SK channel activity of mice with or without diabetes. Mito-Tempo (1 mg/kg/day) was applied to the mice with or without diabetes (n = 10/group) for 4 weeks. In vitro relaxation response of pre-contracted arteries was examined in the presence or absence of the vasodilatory agents. SK channel currents of the isolated mouse heart endothelial cells were measured using whole-cell patch clamp methods. At baseline, coronary endothelium-dependent relaxation responses to ADP and the selective SK channel activator NS309 and endothelial SK channel currents were decreased in diabetic mice compared with that in non-diabetic (ND) mice (p < 0.05). After a 4-week treatment with mito-Tempo, coronary endothelium-dependent relaxation response to ADP or NS309 and endothelial SK channel currents in the diabetic mice was significantly improved when compared with that in untreated diabetic mice (p < 0.05). Interestingly, coronary relaxation responses to ADP and NS309 and endothelial SK channel currents were not significantly changed in ND mice after mito-Tempo treatment, as compared to that of untreated control group. Chronic inhibition of endothelial mROS appears to improve coronary endothelial function/dilation and SK channel activity in diabetes, and mROS inhibitors may be a novel strategy to treat vascular complications in diabetes.
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Affiliation(s)
- Hang Xing
- Cardiothoracic Surgery Research Laboratory, Cardiovascular Research Center, Department of Surgery, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, RI, United States
| | - Zhiqi Zhang
- Cardiothoracic Surgery Research Laboratory, Cardiovascular Research Center, Department of Surgery, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, RI, United States
| | - Guangbin Shi
- Cardiothoracic Surgery Research Laboratory, Cardiovascular Research Center, Department of Surgery, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, RI, United States
| | - Yixin He
- Cardiothoracic Surgery Research Laboratory, Cardiovascular Research Center, Department of Surgery, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, RI, United States
| | - Yi Song
- Cardiothoracic Surgery Research Laboratory, Cardiovascular Research Center, Department of Surgery, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, RI, United States
| | - Yuhong Liu
- Cardiothoracic Surgery Research Laboratory, Cardiovascular Research Center, Department of Surgery, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, RI, United States
| | - Elizabeth O Harrington
- Vascular Research Laboratory, Providence VA Medical Center, Department of Medicine, Alpert Medical School of Brown University, Providence, RI, United States
| | - Frank W Sellke
- Cardiothoracic Surgery Research Laboratory, Cardiovascular Research Center, Department of Surgery, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, RI, United States
| | - Jun Feng
- Cardiothoracic Surgery Research Laboratory, Cardiovascular Research Center, Department of Surgery, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, RI, United States
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Mishra RC, Kyle BD, Kendrick DJ, Svystonyuk D, Kieser TM, Fedak PWM, Wulff H, Braun AP. KCa channel activation normalizes endothelial function in Type 2 Diabetic resistance arteries by improving intracellular Ca 2+ mobilization. Metabolism 2021; 114:154390. [PMID: 33039407 PMCID: PMC7736096 DOI: 10.1016/j.metabol.2020.154390] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 09/28/2020] [Accepted: 09/30/2020] [Indexed: 10/23/2022]
Abstract
BACKGROUND Endothelial dysfunction is an early pathogenic event in the progression of cardiovascular disease in patients with Type 2 Diabetes (T2D). Endothelial KCa2.3 and KCa3.1 K+ channels are important regulators of arterial diameter, and we thus hypothesized that SKA-31, a small molecule activator of KCa2.3 and KCa3.1, would positively influence agonist-evoked dilation in myogenically active resistance arteries in T2D. METHODOLOGY Arterial pressure myography was utilized to investigate endothelium-dependent vasodilation in isolated cremaster skeletal muscle resistance arteries from 22 to 24 week old T2D Goto-Kakizaki rats, age-matched Wistar controls, and small human intra-thoracic resistance arteries from T2D subjects. Agonist stimulated changes in cytosolic free Ca2+ in acutely isolated, single endothelial cells from Wistar and T2D Goto-Kakizaki cremaster and cerebral arteries were examined using Fura-2 fluorescence imaging. MAIN FINDINGS Endothelium-dependent vasodilation in response to acetylcholine (ACh) or bradykinin (BK) was significantly impaired in isolated cremaster arteries from T2D Goto-Kakizaki rats compared with Wistar controls, and similar results were observed in human intra-thoracic arteries. In contrast, inhibition of myogenic tone by sodium nitroprusside, a direct smooth muscle relaxant, was unaltered in both rat and human T2D arteries. Treatment with a threshold concentration of SKA-31 (0.3 μM) significantly enhanced vasodilatory responses to ACh and BK in arteries from T2D Goto-Kakizaki rats and human subjects, whereas only modest effects were observed in non-diabetic arteries of both species. Mechanistically, SKA-31 enhancement of evoked dilation was independent of vascular NO synthase and COX activities. Remarkably, SKA-31 treatment improved agonist-stimulated Ca2+ elevation in acutely isolated endothelial cells from T2D Goto-Kakizaki cremaster and cerebral arteries, but not from Wistar control vessels. In contrast, SKA-31 treatment did not affect intracellular Ca2+ release by the sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) inhibitor cyclopiazonic acid. CONCLUSIONS Collectively, our data demonstrate that KCa channel modulation can acutely restore endothelium-dependent vasodilatory responses in T2D resistance arteries from rats and humans, which appears to involve improved endothelial Ca2+ mobilization.
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Affiliation(s)
- Ramesh C Mishra
- Dept. of Physiology and Pharmacology, Libin Cardiovascular Institute of Alberta, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada
| | - Barry D Kyle
- Dept. of Physiology and Pharmacology, Libin Cardiovascular Institute of Alberta, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada
| | - Dylan J Kendrick
- Dept. of Physiology and Pharmacology, Libin Cardiovascular Institute of Alberta, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada
| | - Daniyil Svystonyuk
- Dept. of Cardiac Sciences, Libin Cardiovascular Institute of Alberta, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada
| | - Teresa M Kieser
- Dept. of Cardiac Sciences, Libin Cardiovascular Institute of Alberta, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada
| | - Paul W M Fedak
- Dept. of Cardiac Sciences, Libin Cardiovascular Institute of Alberta, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada
| | - Heike Wulff
- Dept of Pharmacology, University of California Davis, 451 Health Sciences Drive, Davis, CA 95616, USA
| | - Andrew P Braun
- Dept. of Physiology and Pharmacology, Libin Cardiovascular Institute of Alberta, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada.
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Vasodilatory Effect of Phellinus linteus Extract in Rat Mesenteric Arteries. Molecules 2020; 25:molecules25143160. [PMID: 32664327 PMCID: PMC7397296 DOI: 10.3390/molecules25143160] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 07/08/2020] [Accepted: 07/09/2020] [Indexed: 11/20/2022] Open
Abstract
Phellinus linteus is a well-known medicinal mushroom that is widely used in Asian countries. In several experimental models, Phellinus linteus extracts were reported to have various biological effects, including anti-inflammatory, anti-cancer, hepatoprotective, anti-diabetic, neuroprotective, and anti-angiogenic activity. In the present study, several bioactive compounds, including palmitic acid ethyl ester and linoleic acid, were identified in Phellinus linteus. The intermediate-conductance calcium-activated potassium channel (IKCa) plays an important role in the regulation of the vascular smooth muscle cells’ (VSMCs) contraction and relaxation. The activation of the IKCa channel causes the hyperpolarization and relaxation of VSMCs. To examine whether Phellinus linteus extract causes vasodilation in the mesenteric arteries of rats, we measured the isometric tension using a wire myograph. After the arteries were pre-contracted with U46619 (a thromboxane analogue, 1 µM), Phellinus linteus extract was administered. The Phellinus linteus extract induced vasodilation in a dose-dependent manner, which was independent of the endothelium. To further investigate the mechanism, we used the non-selective K+ channel blocker tetraethylammonium (TEA). TEA significantly abolished Phellinus linteus extract-induced vasodilation. Thus, we tested three different types of K+ channel blockers: iberiotoxin (BKca channel blocker), apamin (SKca channel blocker), and charybdotoxin (IKca channel blocker). Charybdotoxin significantly inhibited Phellinus linteus extract-induced relaxation, while there was no effect from apamin and iberiotoxin. Membrane potential was measured using the voltage-sensitive dye bis-(1,3-dibutylbarbituric acid)-trimethine oxonol (DiBAC4(3)) in the primary isolated vascular smooth muscle cells (VSMCs). We found that the Phellinus linteus extract induced hyperpolarization of VSMCs, which is associated with a reduced phosphorylation level of 20 KDa myosin light chain (MLC20).
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Zhang Z, Shi G, Liu Y, Xing H, Kabakov AY, Zhao AS, Agbortoko V, Kim J, Singh AK, Koren G, Harrington EO, Sellke FW, Feng J. Coronary endothelial dysfunction prevented by small-conductance calcium-activated potassium channel activator in mice and patients with diabetes. J Thorac Cardiovasc Surg 2020; 160:e263-e280. [PMID: 32199659 PMCID: PMC7439127 DOI: 10.1016/j.jtcvs.2020.01.078] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 12/30/2019] [Accepted: 01/31/2020] [Indexed: 11/18/2022]
Abstract
OBJECTIVE To investigate coronary endothelial protection of a small-conductance calcium-activated potassium (SK) channel activator against a period of cardioplegic-hypoxia and reoxygenation (CP-H/R) injury in mice and patients with diabetes (DM) and those without diabetes (nondiabetic [ND]). METHODS Mouse small coronary arteries/heart endothelial cells (MHECs) and human coronary arterial endothelial cells (HCAECs) were dissected from the harvested hearts of mice (n = 16/group) and from discarded right atrial tissue samples of patients with DM and without DM (n = 8/group). The SK current density of MHECs was measured. The in vitro small arteries/arterioles, MHECs, and HCAECs were subjected to 60 minutes of CP hypoxia, followed by 60 minutes of oxygenation. Vessels were treated with or without the selective SK activator NS309 for 5 minutes before and during CP hypoxia. RESULTS DM and/or CP-H/R significantly inhibited the total SK currents of MHECs and HCAECs and significantly diminished the mouse coronary relaxation response to NS309. Administration of NS309 immediately before and during CP hypoxia significantly improved the recovery of coronary endothelial function, as demonstrated by increased relaxation responses to adenosine 5'-diphosphate and substance P compared with those seen in controls (P < .05). This protective effect was more pronounced in vessels from ND mice and patients compared with DM mice and patients (P < .05). Cell surface membrane SK3 expression was significantly reduced after hypoxia, whereas cytosolic SK3 expression was greater than that of the sham control group (P < .05). CONCLUSIONS Application of NS309 immediately before and during CP hypoxia protects mouse and human coronary microvasculature against CP-H/R injury, but this effect is diminished in the diabetic coronary microvasculature. SK inhibition/inactivation and/or internalization/redistribution may contribute to CP-H/R-induced coronary endothelial and vascular relaxation dysfunction.
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Affiliation(s)
- Zhiqi Zhang
- Division of Cardiothoracic Surgery, Rhode Island Hospital, Providence, RI
| | - Guangbin Shi
- Division of Cardiothoracic Surgery, Rhode Island Hospital, Providence, RI
| | - Yuhong Liu
- Division of Cardiothoracic Surgery, Rhode Island Hospital, Providence, RI
| | - Hang Xing
- Division of Cardiothoracic Surgery, Rhode Island Hospital, Providence, RI
| | - Anatoli Y Kabakov
- Cardiovascular Research Center, Rhode Island Hospital, Providence, RI
| | - Amy S Zhao
- Division of Cardiothoracic Surgery, Rhode Island Hospital, Providence, RI
| | - Vahid Agbortoko
- Division of Cardiothoracic Surgery, Rhode Island Hospital, Providence, RI
| | - Justin Kim
- Division of Cardiothoracic Surgery, Rhode Island Hospital, Providence, RI
| | - Arun K Singh
- Division of Cardiothoracic Surgery, Rhode Island Hospital, Providence, RI
| | - Gideon Koren
- Cardiovascular Research Center, Rhode Island Hospital, Providence, RI
| | | | - Frank W Sellke
- Division of Cardiothoracic Surgery, Rhode Island Hospital, Providence, RI
| | - Jun Feng
- Division of Cardiothoracic Surgery, Rhode Island Hospital, Providence, RI.
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Bek T. Translational research in retinal vascular disease. An approach. Acta Ophthalmol 2019; 97:441-450. [PMID: 30801973 DOI: 10.1111/aos.14045] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Accepted: 01/12/2019] [Indexed: 12/24/2022]
Abstract
The clinical presentation of the most frequent vision threatening retinal diseases is dominated by lesions indicating that disturbances in retinal blood flow are involved in the pathogenesis of these diseases. The present review describes the experience from a translational strategy pursued to investigate retinal vascular diseases with diabetic retinopathy as the main object. The normal regulation of retinal blood flow is investigated in porcine retinal vessels in vitro and ex vivo. Subsequently, the in vitro findings are translated to clinical studies in normal persons in vivo, and it is investigated whether the mechanisms are disturbed in retinal vascular disease. This is followed by clinical intervention studies on these diseases. The approach has been used to investigate pressure autoregulation, metabolic autoregulation and vasomotion in retinal vessels. The investigations have shown that retinal vascular tone can be regulated by receptor-specific agonists and antagonists to vasoactive compounds such as purines, prostaglandins and nitric oxide synthesis and that the vasoactive effects can be modulated by the concentration and the mode of administration of these compounds. Additionally, it has been shown that retinal precapillary arterioles and capillaries not visible by ophthalmoscopy may play an important role for the pathophysiology of retinal vascular disease and its treatment. Future studies should focus on investigating normal and pathological regulation of retinal blood flow in these smaller vessels.
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Affiliation(s)
- Toke Bek
- Department of Ophthalmology Aarhus University Hospital Aarhus C DK‐8000 Denmark
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Simonsen U, Winther AK, Oliván-Viguera A, Comerma-Steffensen S, Köhler R, Bek T. Extracellular l-arginine Enhances Relaxations Induced by Opening of Calcium-Activated SKCa Channels in Porcine Retinal Arteriole. Int J Mol Sci 2019; 20:ijms20082032. [PMID: 31027156 PMCID: PMC6515554 DOI: 10.3390/ijms20082032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 04/22/2019] [Accepted: 04/23/2019] [Indexed: 01/27/2023] Open
Abstract
We investigated whether the substrate for nitric oxide (NO) production, extracellular l-arginine, contributes to relaxations induced by activating small (SKCa) conductance Ca2+-activated potassium channels. In endothelial cells, acetylcholine increased 3H-l-arginine uptake, while blocking the SKCa and the intermediate (IKCa) conductance Ca2+-activated potassium channels reduced l-arginine uptake. A blocker of the y+ transporter system, l-lysine also blocked 3H-l-arginine uptake. Immunostaining showed co-localization of endothelial NO synthase (eNOS), SKCa3, and the cationic amino acid transporter (CAT-1) protein of the y+ transporter system in the endothelium. An opener of SKCa channels, cyclohexyl-[2-(3,5-dimethyl-pyrazol-1-yl)-6-methyl-pyrimidin-4-yl]-amine (CyPPA) induced large currents in endothelial cells, and concentration-dependently relaxed porcine retinal arterioles. In the presence of l-arginine, concentration-response curves for CyPPA were leftward shifted, an effect unaltered in the presence of low sodium, but blocked by l-lysine in the retinal arterioles. Our findings suggest that SKCa channel activity regulates l-arginine uptake through the y+ transporter system, and we propose that in vasculature affected by endothelial dysfunction, l-arginine administration requires the targeting of additional mechanisms such as SKCa channels to restore endothelium-dependent vasodilatation.
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Affiliation(s)
- Ulf Simonsen
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Aarhus University, Wilhelm Meyers Allé 4, DK-8000 Aarhus C, Denmark.
| | - Anna K Winther
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Aarhus University, Wilhelm Meyers Allé 4, DK-8000 Aarhus C, Denmark.
| | - Aida Oliván-Viguera
- BESICoS group, Aragón Institute of Engineering Research, IIS-Aragón, University of Zaragoza, 50009 Zaragoza, Spain.
| | - Simon Comerma-Steffensen
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Aarhus University, Wilhelm Meyers Allé 4, DK-8000 Aarhus C, Denmark.
| | - Ralf Köhler
- Aragón Agency for Research and Development (ARAID) at IACS and IIS Aragón, 50009 Zaragoza, Spain.
| | - Toke Bek
- Department of Ophthalmology, Aarhus University Hospital, DK-8000 Aarhus C, Denmark.
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Comerma-Steffensen S, Risso A, Ascanio-Evanoff E, Zerpa H. Endothelium-dependent relaxation mechanisms involve nitric oxide and prostanoids in the isolated bovine digital vein. J Vet Pharmacol Ther 2019; 42:361-367. [PMID: 30888081 DOI: 10.1111/jvp.12758] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Revised: 12/31/2018] [Accepted: 02/09/2019] [Indexed: 02/04/2023]
Abstract
Endothelial dysfunction contributes to the development of ungulate's laminitis. Although extensively studied in equines, the endothelial function is not fully examined in bovine digital veins (BDVs). BDVs were studied under isometric conditions to describe the acetylcholine (ACh) endothelium-dependent relaxation. Concentration-response curves were constructed to phenylephrine, ACh, and sodium nitroprusside (SNP). Relaxation responses were evaluated using either phenylephrine or depolarizing high-potassium Krebs solution (DKS) as precontraction agents. Endothelium denudation and incubation with L-NAME (300 μM), indomethacin (10 μM) or both were used to explore endothelial-mediated mechanisms. Endothelium denudation did not modify phenylephrine and SNP responses, however, significantly (p < 0.05) converted a relaxation (63.2 ± 5%) response to ACh into a contraction (30.3±9%). The ACh-evoked relaxation was significantly (p < 0.05) reduced in the presence of indomethacin (37.5 ± 6%) and L-NAME (6.40 ± 2%). The presence of both inhibitors abolished the ACh-evoked relaxation. Although DKS caused a higher precontraction than phenylephrine, ACh-evoked relaxation (22.4 ± 3.4%) was still observed and was reduced by the combination of inhibitors (7.0 ± 1.0%). The ACh endothelium-dependent relaxation in BDVs is essentially mediated by nitric oxide and endothelium-derived prostanoids. The BDV endothelium function is a dynamic component in the control of the bovine digital blood flow, particularly under endothelial dysfunction conditions when venoconstriction might lead to postcapillary resistance increase.
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Affiliation(s)
- Simon Comerma-Steffensen
- Faculty of Veterinary Sciences, Department of Biomedical Science, Central University of Venezuela, Maracay, Venezuela.,Pharmacology, Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Arnaldo Risso
- Large Animal Medicine, Faculty of Veterinary Medicine, Department of Animal and Public Health, National Experimental University "Romulo Gallegos", Zaraza, Venezuela
| | - Elias Ascanio-Evanoff
- Faculty of Veterinary Sciences, Department of Biomedical Science, Central University of Venezuela, Maracay, Venezuela
| | - Hector Zerpa
- Anatomy, Physiology and Pharmacology Department, School of Veterinary Medicine, Saint George's University, Saint George's, Grenada
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Zhao H, Jiang J, Xia J, Jiang R. Effect of low androgen levels on IKca and SKca3 channels in rat penile corpus cavernosum. Andrologia 2018; 50:e13075. [PMID: 29952429 DOI: 10.1111/and.13075] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2018] [Revised: 04/27/2018] [Accepted: 05/09/2018] [Indexed: 12/12/2022] Open
Affiliation(s)
- Hu Zhao
- Department of Urology; Affiliated Hospital; Southwest Medical University; Luzhou China
| | - Jun Jiang
- Department of thyroid Surgery; Affiliated Hospital; Southwest Medical University; Luzhou China
| | - Jiyi Xia
- Medical research center; Affiliated Hospital; Southwest Medical University; Luzhou China
| | - Rui Jiang
- Department of Urology; Affiliated Hospital; Southwest Medical University; Luzhou China
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14
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Hakim MA, Buchholz JN, Behringer EJ. Electrical dynamics of isolated cerebral and skeletal muscle endothelial tubes: Differential roles of G-protein-coupled receptors and K + channels. Pharmacol Res Perspect 2018; 6:e00391. [PMID: 29636977 PMCID: PMC5889193 DOI: 10.1002/prp2.391] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 02/12/2018] [Indexed: 12/13/2022] Open
Abstract
Electrical dynamics of freshly isolated cerebral endothelium have not been determined independently of perivascular nerves and smooth muscle. We tested the hypothesis that endothelium of cerebral and skeletal muscle arteries differentially utilizes purinergic and muscarinic signaling pathways to activate endothelium‐derived hyperpolarization. Changes in membrane potential (Vm) were recorded in intact endothelial tubes freshly isolated from posterior cerebral and superior epigastric arteries of male and female C57BL/6 mice (age: 3‐8 months). Vm was measured in response to activation of purinergic (P2Y) and muscarinic (M3) receptors in addition to small‐ and intermediate‐conductance Ca2+‐activated K+ (SKCa/IKCa) and inward rectifying K+ (KIR) channels using ATP (100 μmol·L−1), acetylcholine (ACh; 10 μmol·L−1), NS309 (0.01‐10 μmol·L−1), and 15 mmol·L−1 KCl, respectively. Intercellular coupling was demonstrated via transfer of propidium iodide dye and electrical current (±0.5‐3 nA) through gap junctions. With similarities observed across gender, peak hyperpolarization to ATP and ACh in skeletal muscle endothelial tubes was ~twofold and ~sevenfold higher, respectively, vs cerebral endothelial tubes, whereas responses to NS309 were similar (from resting Vm ~−30 mV to maximum ~−80 mV). Hyperpolarization (~8 mV) occurred during 15 mmol·L−1 KCl treatment in cerebral but not skeletal muscle endothelial tubes. Despite weaker hyperpolarization during endothelial GPCR stimulation in cerebral vs skeletal muscle endothelium, the capability for robust SKCa/IKCa activity is preserved across brain and skeletal muscle. As vascular reactivity decreases with aging and cardiovascular disease, endothelial K+ channel activity may be calibrated to restore blood flow to respective organs regardless of gender.
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Affiliation(s)
- Md A Hakim
- Basic Sciences Loma Linda University Loma Linda CA USA
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15
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Khaddaj Mallat R, Mathew John C, Kendrick DJ, Braun AP. The vascular endothelium: A regulator of arterial tone and interface for the immune system. Crit Rev Clin Lab Sci 2017; 54:458-470. [PMID: 29084470 DOI: 10.1080/10408363.2017.1394267] [Citation(s) in RCA: 83] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
As the primary interface between the blood and various tissues of the body, the vascular endothelium exhibits a diverse range of roles and activities, all of which contribute to the overall health and function of the cardiovascular system. In this focused review, we discuss several key aspects of endothelial function, how this may be compromised and subsequent consequences. Specifically, we examine the dynamic regulation of arterial contractility and distribution of blood flow through the generation of chemical and electrical signaling events that impinge upon vascular smooth muscle. The endothelium can generate a diverse range of vasoactive compounds and signals, most of which act locally to adjust blood flow in a dynamic fashion to match tissue metabolism. Disruption of these vascular signaling processes (e.g. reduced nitric oxide bioavailability) is typically referred to as endothelial dysfunction, which is a recognized risk factor for cardiovascular disease in patients and occurs early in the development and progression of hypertension, atherosclerosis and tissue ischemia. Endothelial dysfunction is also associated with type-2 Diabetes and aging and increased mechanistic knowledge of the cellular changes contributing to these effects may provide important clues for interventional strategies. The endothelium also serves as the initial site of interaction for immune cells entering tissues in response to damage and acts to facilitate the actions of both the innate and acquired immune systems to interact with the vascular wall. In addition to representing the main cell type responsible for the formation of new blood vessels (i.e. angiogenesis) within the vasculature, the endothelium is also emerging as a source of extracellular vesicle or microparticles for the transport of signaling molecules and other cellular materials to nearby, or remote, sites in the body. The characteristics of released microparticles appear to change with the functional status of the endothelium; thus, these microparticles may represent novel biomarkers of endothelial health and more serious cardiovascular disease.
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Affiliation(s)
- Rayan Khaddaj Mallat
- a Department of Physiology and Pharmacology, Cumming School of Medicine , University of Calgary, and Libin Cardiovascular Institute of Alberta , Calgary , Canada
| | - Cini Mathew John
- a Department of Physiology and Pharmacology, Cumming School of Medicine , University of Calgary, and Libin Cardiovascular Institute of Alberta , Calgary , Canada
| | - Dylan J Kendrick
- a Department of Physiology and Pharmacology, Cumming School of Medicine , University of Calgary, and Libin Cardiovascular Institute of Alberta , Calgary , Canada
| | - Andrew P Braun
- a Department of Physiology and Pharmacology, Cumming School of Medicine , University of Calgary, and Libin Cardiovascular Institute of Alberta , Calgary , Canada
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Comerma-Steffensen SG, Carvacho I, Hedegaard ER, Simonsen U. Small and Intermediate Calcium-Activated Potassium Channel Openers Improve Rat Endothelial and Erectile Function. Front Pharmacol 2017; 8:660. [PMID: 28993731 PMCID: PMC5619997 DOI: 10.3389/fphar.2017.00660] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 09/05/2017] [Indexed: 12/13/2022] Open
Abstract
Modulation of endothelial calcium-activated potassium (KCa) channels has been proposed as an approach to restore endothelial function. The present study investigated whether novel openers of KCa channels with small (KCa2.x) and intermediate (KCa3.1) conductance, NS309 and NS4591, improve endothelium-dependent relaxation and erectile function. Rat corpus cavernosum (CC) strips were mounted for isometric tension recording and processed for immunoblotting. Mean arterial pressure (MAP), intracavernosal pressure (ICP), and electrocardiographic (ECG) measurements were conducted in anesthetized rats. Immunoblotting revealed the presence of KCa2.3 and large KCa conductance (KCa1.1) channels in the corpus cavernosum. NS309 and NS4591 increased current in CC endothelial cells in whole cell patch clamp experiments. Relaxation induced by NS309 (<1 μM) was inhibited by endothelial cell removal and high extracellular potassium. An inhibitor of nitric oxide (NO) synthase, and blockers of KCa2.x and KCa1.1 channels, apamin and iberiotoxin also inhibited NS309 relaxation. Incubation with NS309 (0.5 μM) markedly enhanced acetylcholine relaxation. Basal erectile function (ICP/MAP) increased during administration of NS309. Increases in ICP/MAP after cavernous nerve stimulation with NS309 were unchanged, whereas NS4591 significantly improved erectile function. Administration of NS309 and NS4591 caused small changes in the electrocardiogram, but neither arrhythmic events nor prolongation of the QTc interval were observed. The present study suggests that openers of KCa2.x and KCa3.1 channels improve endothelial and erectile function. The effects of NS309 and NS4591 on heart rate and ECG are small, but will require additional safety studies before evaluating whether activation of KCa2.3 channels has a potential for treatment of erectile dysfunction.
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Affiliation(s)
- Simon G. Comerma-Steffensen
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Aarhus UniversityAarhus, Denmark
- Animal Physiology, Department of Biomedical Sciences, Veterinary Sciences Faculty, Central University of VenezuelaMaracay, Venezuela
| | - Ingrid Carvacho
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Aarhus UniversityAarhus, Denmark
- Department of Biology and Chemistry, Faculty of Basic Sciences, Universidad Católica del MauleTalca, Chile
| | - Elise R. Hedegaard
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Aarhus UniversityAarhus, Denmark
| | - Ulf Simonsen
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Aarhus UniversityAarhus, Denmark
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Kratholm NM, Jensen PS, Kringelholt S, Simonsen U, Bek T. Activation of Veratridine Sensitive Sodium Channels, But not Electrical Field Stimulation, Dilates Porcine Retinal Arterioles with Preserved Perivascular Tissue. Curr Eye Res 2017; 42:1497-1502. [PMID: 28910154 DOI: 10.1080/02713683.2017.1337156] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
PURPOSE Disturbances in retinal blood flow are a prominent feature of vision threatening retinal diseases. The regulation of tone in retinal resistance vessels involves the perivascular retinal tissue, but it is unknown to what extent neurons or glial cells contribute to the effect. Therefore, the purpose of the present study was to study the contribution of neurons in the perivascular retina to vascular tone during activation of voltage-gated sodium channels with veratridine and electrical field stimulation (EFS). METHODS Porcine retinal arterioles with and without perivascular tissue were mounted in an isometric myograph system for studying the effects of the voltage-gated sodium channel opener veratridine and EFS on retinal vascular tone. RESULTS Veratridine induced concentration-dependent relaxation of retinal arterioles which was more pronounced in arterioles with preserved perivascular retinal tissue than in isolated vessels. In the presence of this tissue, veratridine-induced relaxation was inhibited by the voltage-gated sodium channel blocker tetrodotoxin and the nitric oxide synthase inhibitor, Nω-Nitro-L-arginine methyl ester (L-NAME), but was unaffected by the inhibition of the cyclo-oxygenase inbitior ibuprofen and by blocking of adenosine receptors with 8-(p-Sulfophenyl)theophylline hydrate (8-PSPT). Electrical field stimulation induced no changes in retinal vascular tone. CONCLUSIONS Sodium channels of neuronal origin are likely to be involved in the regulation of retinal vascular tone. The lack of effect of EFS on retinal vascular tone may be due to the lack of autonomic nerves in the retina.
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Affiliation(s)
- Nils M Kratholm
- a Department of Ophthalmology , Aarhus University Hospital , Aarhus C , Denmark
| | - Peter Skov Jensen
- a Department of Ophthalmology , Aarhus University Hospital , Aarhus C , Denmark
| | - Sidse Kringelholt
- a Department of Ophthalmology , Aarhus University Hospital , Aarhus C , Denmark
| | - Ulf Simonsen
- b Department of Biomedicine (Pharmacology) , University of Aarhus , Aarhus C , Denmark
| | - Toke Bek
- a Department of Ophthalmology , Aarhus University Hospital , Aarhus C , Denmark
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18
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Calycosin and Formononetin Induce Endothelium-Dependent Vasodilation by the Activation of Large-Conductance Ca 2+-Activated K + Channels (BK Ca). EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2016; 2016:5272531. [PMID: 27994632 PMCID: PMC5141325 DOI: 10.1155/2016/5272531] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 09/26/2016] [Accepted: 10/19/2016] [Indexed: 12/13/2022]
Abstract
Calycosin and formononetin are two structurally similar isoflavonoids that have been shown to induce vasodilation in aorta and conduit arteries, but study of their actions on endothelial functions is lacking. Here, we demonstrated that both isoflavonoids relaxed rat mesenteric resistance arteries in a concentration-dependent manner, which was reduced by endothelial disruption and nitric oxide synthase (NOS) inhibition, indicating the involvement of both endothelium and vascular smooth muscle. In addition, the endothelium-dependent vasodilation, but not the endothelium-independent vasodilation, was blocked by BKCa inhibitor iberiotoxin (IbTX). Using human umbilical vein endothelial cells (HUVECs) as a model, we showed calycosin and formononetin induced dose-dependent outwardly rectifying K+ currents using whole cell patch clamp. These currents were blocked by tetraethylammonium chloride (TEACl), charybdotoxin (ChTX), or IbTX, but not apamin. We further demonstrated that both isoflavonoids significantly increased nitric oxide (NO) production and upregulated the activities and expressions of endothelial NOS (eNOS) and neuronal NOS (nNOS). These results suggested that calycosin and formononetin act as endothelial BKCa activators for mediating endothelium-dependent vasodilation through enhancing endothelium hyperpolarization and NO production. Since activation of BKCa plays a role in improving behavioral and cognitive disorders, we suggested that these two isoflavonoids could provide beneficial effects to cognitive disorders through vascular regulation.
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19
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Inhibition of Myogenic Tone in Rat Cremaster and Cerebral Arteries by SKA-31, an Activator of Endothelial KCa2.3 and KCa3.1 Channels. J Cardiovasc Pharmacol 2016; 66:118-27. [PMID: 25815673 DOI: 10.1097/fjc.0000000000000252] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Endothelial KCa2.3 and KCa3.1 channels contribute to the regulation of myogenic tone in resistance arteries by Ca(2+)-mobilizing vasodilatory hormones. To define further the functional role of these channels in distinct vascular beds, we have examined the vasodilatory actions of the KCa channel activator SKA-31 in myogenically active rat cremaster and middle cerebral arteries. Vessels pressurized to 70 mm Hg constricted by 80-100 μm (ie, 25%-45% of maximal diameter). SKA-31 (10 μM) inhibited myogenic tone by 80% in cremaster and ∼65% in middle cerebral arteries, with IC50 values of ∼2 μM in both vessels. These vasodilatory effects were largely prevented by the KCa2.3 blocker UCL1684 and the KCa3.1 blocker TRAM-34 and abolished by endothelial denudation. Preincubation with N(G) nitro L-arginine methyl ester (L-NAME, 0.1 mM) did not affect the inhibitory response to SKA-31, but attenuated the ACh-evoked dilation by ∼45%. Penitrem-A, a blocker of BK(Ca) channels, did not alter SKA-31 evoked vasodilation but did reduce the inhibition of myogenic tone by ACh, the BKCa channel activator NS1619, and sodium nitroprusside. Collectively, these data demonstrate that SKA-31 produces robust inhibition of myogenic tone in resistance arteries isolated from distinct vascular beds in an endothelium-dependent manner.
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20
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Calcium-Activated Potassium Channels: Potential Target for Cardiovascular Diseases. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2015; 104:233-261. [PMID: 27038376 DOI: 10.1016/bs.apcsb.2015.11.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Ca(2+)-activated K(+) channels (KCa) are classified into three subtypes: big conductance (BKCa), intermediate conductance (IKCa), and small conductance (SKCa) KCa channels. The three types of KCa channels have distinct physiological or pathological functions in cardiovascular system. BKCa channels are mainly expressed in vascular smooth muscle cells (VSMCs) and inner mitochondrial membrane of cardiomyocytes, activation of BKCa channels in these locations results in vasodilation and cardioprotection against cardiac ischemia. IKCa channels are expressed in VSMCs, endothelial cells, and cardiac fibroblasts and involved in vascular smooth muscle proliferation, migration, vessel dilation, and cardiac fibrosis. SKCa channels are widely expressed in nervous and cardiovascular system, and activation of SKCa channels mainly contributes membrane hyperpolarization. In this chapter, we summarize the physiological and pathological roles of the three types of KCa channels in cardiovascular system and put forward the possibility of KCa channels as potential target for cardiovascular diseases.
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21
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Aizawa N, Wakamatsu D, Kida J, Otsuki T, Saito Y, Matsuya H, Homma Y, Igawa Y. Inhibitory effects of retigabine, a Kv7 channel activator, on mechanosensitive primary bladder afferent activities and nociceptive behaviors in rats. Neurourol Urodyn 2015; 36:280-285. [DOI: 10.1002/nau.22920] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 10/13/2015] [Indexed: 01/25/2023]
Affiliation(s)
- Naoki Aizawa
- Department of Continence Medicine; The University of Tokyo Graduate School of Medicine; Tokyo Japan
| | - Daisuke Wakamatsu
- Discovery Research Laboratories 4; Department of Biology & Pharmacology; ONO Pharmaceutical Co., Ltd.; Osaka Japan
| | - Jun Kida
- Discovery Research Laboratories 4; Department of Biology & Pharmacology; ONO Pharmaceutical Co., Ltd.; Osaka Japan
| | - Takeya Otsuki
- Discovery Research Laboratories 4; Department of Biology & Pharmacology; ONO Pharmaceutical Co., Ltd.; Osaka Japan
| | - Yasuho Saito
- Department of Urology; The University of Tokyo Graduate School of Medicine; Tokyo Japan
| | - Hidekazu Matsuya
- Discovery Research Laboratories 4; Department of Biology & Pharmacology; ONO Pharmaceutical Co., Ltd.; Osaka Japan
| | - Yukio Homma
- Department of Urology; The University of Tokyo Graduate School of Medicine; Tokyo Japan
| | - Yasuhiko Igawa
- Department of Continence Medicine; The University of Tokyo Graduate School of Medicine; Tokyo Japan
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22
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Winther AK, Dalsgaard T, Hedegaard ER, Simonsen U. Involvement of hydrogen sulfide in perivascular and hypoxia-induced inhibition of endothelin contraction in porcine retinal arterioles. Nitric Oxide 2015; 50:1-9. [DOI: 10.1016/j.niox.2015.07.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Revised: 06/26/2015] [Accepted: 07/16/2015] [Indexed: 01/14/2023]
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Peixoto-Neves D, Wang Q, Leal-Cardoso JH, Rossoni LV, Jaggar JH. Eugenol dilates mesenteric arteries and reduces systemic BP by activating endothelial cell TRPV4 channels. Br J Pharmacol 2015; 172:3484-94. [PMID: 25832173 DOI: 10.1111/bph.13156] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 01/27/2015] [Accepted: 03/15/2015] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND AND PURPOSE Eugenol, a vanilloid molecule found in some dietary plants, relaxes vasculature in part via an endothelium-dependent process; however, the mechanisms involved are unclear. Here, we investigated the endothelial cell-mediated mechanism by which eugenol modulates rat mesenteric artery contractility and systemic BP. EXPERIMENTAL APPROACH The isometric tension of rat mesenteric arteries (size 200-300 μm) was measured using wire myography; non-selective cation currents (ICat ) were recorded in endothelial cells using patch clamp electrophysiology. Mean arterial pressure (MAP) and heart rate (HR) were determined in anaesthetized rats. KEY RESULTS Eugenol relaxed endothelium-intact arteries in a concentration-dependent manner and this effect was attenuated by endothelium denudation. L-NAME, a NOS inhibitor, a combination of TRAM-34 and apamin, selective blockers of intermediate and small conductance Ca(2+) -activated K(+) channels, respectively, and HC-067047, a TRPV4 channel inhibitor, but not indomethacin, a COX inhibitor, reduced eugenol-induced relaxation in endothelium-intact arteries. Eugenol activated HC-067047-sensitive ICat in mesenteric artery endothelial cells. Short interfering RNA (siRNA)-mediated TRPV4 knockdown abolished eugenol-induced ICat activation. An i.v. injection of eugenol caused an immediate, transient reduction in both MAP and HR, which was followed by prolonged, sustained hypotension in anaesthetized rats. This sustained hypotension was blocked by HC-067047. CONCLUSIONS AND IMPLICATIONS Eugenol activates TRPV4 channels in mesenteric artery endothelial cells, leading to vasorelaxation, and reduces systemic BP in vivo. Eugenol may be therapeutically useful as an antihypertensive agent and is a viable molecular candidate from which to develop second-generation TRPV4 channel activators that reduce BP.
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Affiliation(s)
- Dieniffer Peixoto-Neves
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN, USA.,Laboratório de Eletrofisiologia, Instituto Superior de Ciências Biomédicas, Universidade Estadual do Ceará, Fortaleza, Ceará, Brazil
| | - Qian Wang
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Jose H Leal-Cardoso
- Laboratório de Eletrofisiologia, Instituto Superior de Ciências Biomédicas, Universidade Estadual do Ceará, Fortaleza, Ceará, Brazil
| | - Luciana V Rossoni
- Laboratório de Fisiologia Vascular, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, Brazil
| | - Jonathan H Jaggar
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN, USA
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Abstract
Vascular thiol redox state has been shown to modulate vasodilator functions in large conductance Ca2+ -activated K+ channels and other related channels. However, the role of vascular redox in small resistance arteries is unknown. To determine how in vivo modulation of thiol redox state affects small resistance arteries relaxation, we generated a transgenic mouse strain that overexpresses thioredoxin, a small redox protein (Trx-Tg), and another strain that is thioredoxin-deficient (dnTrx-Tg). The redox state of the mesenteric arteries (MAs) in Trx-Tg mice is found to be predominantly in reduced state; in contrast, MAs from dnTrx-Tg mice remain in oxidized state. Thus, we created an in vivo redox system of mice and isolated the second-order branches of the main superior MAs from wild-type, Trx-Tg, or dnTrx-Tg mice to assess endothelium-dependent relaxing responses in a wire myograph. In MAs isolated from Trx-Tg mice, we observed an enhanced intermediate-conductance Ca2+ -activated potassium channel contribution resulting in a larger endothelium-dependent hyperpolarizing (EDH) relaxation in response to indirect (acetylcholine) and direct (NS309) opening of endothelial calcium-activated potassium channels. MAs derived from dnTrx-Tg mice showed both blunted nitric oxide-mediated and EDH-mediated relaxation compared with Trx-Tg mice. In a control study, diamide decreased EDH relaxations in MAs of wild-type mice, whereas dithiothreitol improved EDH relaxations and was able to restore the diamide-induced impairment in EDH response. Furthermore, the basal or angiotensin II-mediated systolic blood pressure remained significantly lower in Trx-Tg mice compared with wild-type or dnTrx-Tg mice, thus directly establishing redox-mediated EDH in blood pressure control.
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Affiliation(s)
- Rob H P Hilgers
- From the Department of Anesthesiology and Center for Excellence in Cardiovascular Research, Texas Tech University Health Sciences Center, Lubbock
| | - Kumuda C Das
- From the Department of Anesthesiology and Center for Excellence in Cardiovascular Research, Texas Tech University Health Sciences Center, Lubbock.
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Climent B, Moreno L, Martínez P, Contreras C, Sánchez A, Pérez-Vizcaíno F, García-Sacristán A, Rivera L, Prieto D. Upregulation of SK3 and IK1 channels contributes to the enhanced endothelial calcium signaling and the preserved coronary relaxation in obese Zucker rats. PLoS One 2014; 9:e109432. [PMID: 25302606 PMCID: PMC4193814 DOI: 10.1371/journal.pone.0109432] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Accepted: 09/01/2014] [Indexed: 12/19/2022] Open
Abstract
Background and Aims Endothelial small- and intermediate-conductance KCa channels, SK3 and IK1, are key mediators in the endothelium-derived hyperpolarization and relaxation of vascular smooth muscle and also in the modulation of endothelial Ca2+ signaling and nitric oxide (NO) release. Obesity is associated with endothelial dysfunction and impaired relaxation, although how obesity influences endothelial SK3/IK1 function is unclear. Therefore we assessed whether the role of these channels in the coronary circulation is altered in obese animals. Methods and Results In coronary arteries mounted in microvascular myographs, selective blockade of SK3/IK1 channels unmasked an increased contribution of these channels to the ACh- and to the exogenous NO- induced relaxations in arteries of Obese Zucker Rats (OZR) compared to Lean Zucker Rats (LZR). Relaxant responses induced by the SK3/IK1 channel activator NS309 were enhanced in OZR and NO- endothelium-dependent in LZR, whereas an additional endothelium-independent relaxant component was found in OZR. Fura2-AM fluorescence revealed a larger ACh-induced intracellular Ca2+ mobilization in the endothelium of coronary arteries from OZR, which was inhibited by blockade of SK3/IK1 channels in both LZR and OZR. Western blot analysis showed an increased expression of SK3/IK1 channels in coronary arteries of OZR and immunohistochemistry suggested that it takes place predominantly in the endothelial layer. Conclusions Obesity may induce activation of adaptive vascular mechanisms to preserve the dilator function in coronary arteries. Increased function and expression of SK3/IK1 channels by influencing endothelial Ca2+ dynamics might contribute to the unaltered endothelium-dependent coronary relaxation in the early stages of obesity.
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Affiliation(s)
- Belén Climent
- Departamento de Fisiología, Facultad de Farmacia, Universidad Complutense, Madrid, Spain
- * E-mail: (BC); (DP)
| | - Laura Moreno
- Departamento de Farmacología, Facultad de Medicina, Universidad Complutense, Madrid, Spain
| | - Pilar Martínez
- Departamento de Anatomía y Anatomía Patológica Comparadas, Facultad de Veterinaria, Universidad Complutense, Madrid, Spain
| | - Cristina Contreras
- Departamento de Fisiología, Facultad de Farmacia, Universidad Complutense, Madrid, Spain
| | - Ana Sánchez
- Departamento de Fisiología, Facultad de Farmacia, Universidad Complutense, Madrid, Spain
| | | | | | - Luis Rivera
- Departamento de Fisiología, Facultad de Farmacia, Universidad Complutense, Madrid, Spain
| | - Dolores Prieto
- Departamento de Fisiología, Facultad de Farmacia, Universidad Complutense, Madrid, Spain
- * E-mail: (BC); (DP)
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Xavier FE, Blanco-Rivero J, Sastre E, Caracuel L, Callejo M, Balfagón G. Tranilast increases vasodilator response to acetylcholine in rat mesenteric resistance arteries through increased EDHF participation. PLoS One 2014; 9:e100356. [PMID: 24992476 PMCID: PMC4081117 DOI: 10.1371/journal.pone.0100356] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Accepted: 05/26/2014] [Indexed: 12/23/2022] Open
Abstract
Background and Purpose Tranilast, in addition to its capacity to inhibit mast cell degranulation, has other biological effects, including inhibition of reactive oxygen species, cytokines, leukotrienes and prostaglandin release. In the current study, we analyzed whether tranilast could alter endothelial function in rat mesenteric resistance arteries (MRA). Experimental Approach Acetylcholine-induced relaxation was analyzed in MRA (untreated and 1-hour tranilast treatment) from 6 month-old Wistar rats. To assess the possible participation of endothelial nitric oxide or prostanoids, acetylcholine-induced relaxation was analyzed in the presence of L-NAME or indomethacin. The participation of endothelium-derived hyperpolarizing factor (EDHF) in acetylcholine-induced response was analyzed by preincubation with TRAM-34 plus apamin or by precontraction with a high K+ solution. Nitric oxide (NO) and superoxide anion levels were measured, as well as vasomotor responses to NO donor DEA-NO and to large conductance calcium-activated potassium channel opener NS1619. Key Results Acetylcholine-induced relaxation was greater in tranilast-incubated MRA. Acetylcholine-induced vasodilation was decreased by L-NAME in a similar manner in both experimental groups. Indomethacin did not modify vasodilation. Preincubation with a high K+ solution or TRAM-34 plus apamin reduced the vasodilation to ACh more markedly in tranilast-incubated segments. NO and superoxide anion production, and vasodilator responses to DEA-NO or NS1619 remained unmodified in the presence of tranilast. Conclusions and Implications Tranilast increased the endothelium-dependent relaxation to acetylcholine in rat MRA. This effect is independent of the nitric oxide and cyclooxygenase pathways but involves EDHF, and is mediated by an increased role of small conductance calcium-activated K+ channels.
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Affiliation(s)
- Fabiano E. Xavier
- Departamento de Fisiologia e Farmacologia, Centro de Ciências Biológicas, Universidade Federal de Pernambuco, Recife, Brazil
| | - Javier Blanco-Rivero
- Departamento de Fisiología, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain
- Instituto de Investigación Sanitaria IdIPaz, Madrid, Spain
| | - Esther Sastre
- Departamento de Fisiología, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain
- Instituto de Investigación Sanitaria IdIPaz, Madrid, Spain
| | - Laura Caracuel
- Departamento de Fisiología, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain
- Instituto de Investigación Sanitaria IdIPaz, Madrid, Spain
| | - María Callejo
- Departamento de Fisiología, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain
| | - Gloria Balfagón
- Departamento de Fisiología, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain
- Instituto de Investigación Sanitaria IdIPaz, Madrid, Spain
- * E-mail:
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A pharmacologic activator of endothelial KCa channels enhances coronary flow in the hearts of type 2 diabetic rats. J Mol Cell Cardiol 2014; 72:364-73. [DOI: 10.1016/j.yjmcc.2014.04.013] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Revised: 03/28/2014] [Accepted: 04/21/2014] [Indexed: 11/21/2022]
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Radenković M, Stojanović M, Skorupan N, Prostran M. Pharmacological analysis of the rat femoral artery response to bradykinin. Sci Pharm 2013; 81:749-61. [PMID: 24106671 PMCID: PMC3791937 DOI: 10.3797/scipharm.1305-13] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Accepted: 06/04/2013] [Indexed: 11/22/2022] Open
Abstract
Bradykinin (BK) plays an important role in different physiological processes including the general preservation and modulation of vascular systems. The present study was designed in order to examine the effect of BK on isolated rat femoral artery rings and to investigate the participation of intact endothelium, cyclooxygenase products, Ca2+ channels, Na+/K+–ATPase, and B2 kinin receptors in BK-induced action. Circular artery segments were placed in organ baths. The endothelium was mechanically removed from some arteries. Concentration–contraction curves for BK were obtained in the rings previously equilibrated at the basal tone. BK produced a concentration–dependent contraction, which was reduced by endothelial denudation. The BK–induced effect was almost completely inhibited by indomethacin (cyclooxygenase inhibitor) or OKY–046 (thromboxane A2–synthase inhibitor). Nifedipine (Ca2+ channel blocker), ouabain (Na+/K+–ATPase inhibitor), or HOE–140 (selective B2 kinin receptor antagonist) significantly reduced the BK–evoked effect. In conclusion, it can be proposed that BK produces concentration– and endothelium–dependent contractions of the isolated rat femoral artery, which is for the most part a consequence of B2 kinin receptor activation. Cyclooxygenase contractile products, especially thromboxane A2, play a significant role in this course of action. The transduction mechanism involved in the process of BK–induced femoral artery contraction include the activation of voltage–gated Ca2+ channels, and in a smaller extent Na+/K+–ATPase as well.
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Affiliation(s)
- Miroslav Radenković
- Department of Pharmacology, Clinical Pharmacology and Toxicology; Faculty of Medicine; University of Belgrade; PO Box 38; 11129 Belgrade; Serbia
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Liu J, Feener EP. Plasma kallikrein-kinin system and diabetic retinopathy. Biol Chem 2013; 394:319-28. [PMID: 23362193 DOI: 10.1515/hsz-2012-0316] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Accepted: 01/09/2013] [Indexed: 12/12/2022]
Abstract
Diabetic retinopathy (DR) occurs, to some extent, in most people with at least 20 years' duration of diabetes mellitus. The progression of DR to its sight-threatening stages is usually associated with the worsening of underlying retinal vascular dysfunction and disease. The plasma kallikrein-kinin system (KKS) is activated during vascular injury, where it mediates important functions in innate inflammation, blood flow, and coagulation. Recent findings from human vitreous proteomics and experimental studies on diabetic animal models have implicated the KKS in contributing to DR. Vitreous fluid from people with advanced stages of DR contains increased levels of plasma KKS components, including plasma kallikrein (PK), coagulation factor XII, and high-molecular-weight kininogen. Both bradykinin B1 and B2 receptor isoforms (B1R and B2R, respectively) are expressed in human retina, and retinal B1R levels are increased in diabetic rodents. The activation of the intraocular KKS induces retinal vascular permeability, vasodilation, and retinal thickening, and these responses are exacerbated in diabetic rats. Preclinical studies have shown that the administration of PK inhibitors and B1R antagonists to diabetic rats ameliorates retinal vascular hyperpermeability and inflammation. These findings suggest that components of plasma KKS are potential therapeutic targets for diabetic macular edema.
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Affiliation(s)
- Jia Liu
- Research Division, Joslin Diabetes Center, Department of Medicine, Harvard Medical School, One Joslin Place, Boston, MA 02215, USA
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Itoh T, Maekawa T, Shibayama Y. Characteristics of ACh-induced hyperpolarization and relaxation in rabbit jugular vein. Br J Pharmacol 2013; 167:682-96. [PMID: 22595036 DOI: 10.1111/j.1476-5381.2012.02038.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND AND PURPOSE The roles played by endothelium-derived NO and prostacyclin and by endothelial cell hyperpolarization in ACh-induced relaxation have been well characterized in arteries. However, the mechanisms underlying ACh-induced relaxation in veins remain to be fully clarified. EXPERIMENTAL APPROACH ACh-induced smooth muscle cell (SMC) hyperpolarization and relaxation were measured in endothelium-intact and -denuded preparations of rabbit jugular vein. KEY RESULTS In endothelium-intact preparations, ACh (≤ 10⁻⁸ M) marginally increased the intracellular concentration of Ca²⁺ ([Ca²⁺](i)) in endothelial cells but did not alter the SMC membrane potential. However, ACh (10⁻¹⁰ -10⁻⁸ M) induced a concentration-dependent relaxation during the contraction induced by PGF(2α) and this relaxation was blocked by the NO synthase inhibitor N(ω) -nitro-l-arginine. ACh (10⁻⁸ -10⁻⁶ M) concentration-dependently increased endothelial [Ca²⁺](i) and induced SMC hyperpolarization and relaxation. These SMC responses were blocked in the combined presence of apamin [blocker of small-conductance Ca²⁺-activated K⁺ (SK(Ca) , K(Ca) 2.3) channel], TRAM 34 [blocker of intermediate-conductance Ca²⁺ -activated K⁺ (IK(Ca) , K(Ca) 3.1) channel] and margatoxin [blocker of subfamily of voltage-gated K⁺ (K(V) ) channel, K(V) 1]. CONCLUSIONS AND IMPLICATIONS In rabbit jugular vein, NO plays a primary role in endothelium-dependent relaxation at very low concentrations of ACh (10⁻¹⁰ -10⁻⁸ M). At higher concentrations, ACh (10⁻⁸ -3 × 10⁻⁶ M) induces SMC hyperpolarization through activation of endothelial IK(Ca) , K(V) 1 and (possibly) SK(Ca) channels and produces relaxation. These results imply that ACh regulates rabbit jugular vein tonus through activation of two endothelium-dependent regulatory mechanisms.
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Affiliation(s)
- Takeo Itoh
- Department of Pharmacology, Graduate School of Medical Sciences, Nagoya City University, Japan.
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Kroigaard C, Kudryavtseva O, Dalsgaard T, Wandall-Frostholm C, Olesen SP, Simonsen U. KCa3.1 channel downregulation and impaired endothelium-derived hyperpolarization-type relaxation in pulmonary arteries from chronically hypoxic rats. Exp Physiol 2013; 98:957-69. [DOI: 10.1113/expphysiol.2012.066340] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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Abstract
The present review first summarizes the complex chain of events, in endothelial and vascular smooth muscle cells, that leads to endothelium-dependent relaxations (vasodilatations) due to the generation of nitric oxide (NO) by endothelial nitric oxide synthase (eNOS) and how therapeutic interventions may improve the bioavailability of NO and thus prevent/cure endothelial dysfunction. Then, the role of other endothelium-derived mediators (endothelium-derived hyperpolarizing (EDHF) and contracting (EDCF) factors, endothelin-1) and signals (myoendothelial coupling) is summarized also, with special emphasis on their interaction(s) with the NO pathway, which make the latter not only a major mediator but also a key regulator of endothelium-dependent responses.
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Mishra RC, Belke D, Wulff H, Braun AP. SKA-31, a novel activator of SK(Ca) and IK(Ca) channels, increases coronary flow in male and female rat hearts. Cardiovasc Res 2012; 97:339-48. [PMID: 23118129 DOI: 10.1093/cvr/cvs326] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
AIMS Endothelial SK(Ca) and IK(Ca) channels play an important role in the regulation of vascular function and systemic blood pressure. Based on our previous findings that small molecule activators of SK(Ca) and IK(Ca) channels (i.e. NS309 and SKA-31) can inhibit myogenic tone in isolated resistance arteries, we hypothesized that this class of compounds may induce effective vasodilation in an intact vascular bed, such as the coronary circulation. METHODS AND RESULTS In a Langendorff-perfused, beating rat heart preparation, acute bolus administrations of SKA-31 (0.01-5 µg) dose-dependently increased total coronary flow (25-30%) in both male and female hearts; these responses were associated with modest, secondary increases in left ventricular (LV) systolic pressure and heart rate. SKA-31 evoked responses in coronary flow, LV pressure, and heart rate were qualitatively comparable to acute responses evoked by bradykinin (1 µg) and adenosine (10 µg). In the presence of apamin and TRAM-34, selective blockers of SK(Ca) and IK(Ca) channels, respectively, SKA-31 and bradykinin-induced responses were largely inhibited, whereas the adenosine-induced changes were blocked by ∼40%; TRAM-34 alone produced less inhibition. Sodium nitroprusside (SNP, 0.2 μg bolus dose) evoked changes in coronary flow, LV pressure, and heart rate were similar to those induced by SKA-31, but were unaffected by apamin + TRAM-34. The NOS inhibitor L-NNA reduced bradykinin- and adenosine-evoked changes, but did not affect responses to either SKA-31 or SNP. CONCLUSION Our study demonstrates that SKA-31 can rapidly and reversibly induce dilation of the coronary circulation in intact functioning hearts under basal flow and contractility conditions.
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Affiliation(s)
- Ramesh C Mishra
- Department of Physiology and Pharmacology, Faculty of Medicine, University of Calgary, 3330 Hospital Dr. NW, Calgary, AB, Canada T2N 4N1
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Joshi A, Woodman OL. Increased nitric oxide activity compensates for increased oxidative stress to maintain endothelial function in rat aorta in early type 1 diabetes. Naunyn Schmiedebergs Arch Pharmacol 2012; 385:1083-94. [PMID: 22965470 DOI: 10.1007/s00210-012-0794-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2012] [Accepted: 08/27/2012] [Indexed: 02/07/2023]
Abstract
Hyperglycaemia and oxidative stress are known to acutely cause endothelial dysfunction in vitro, but in the initial stages of diabetes, endothelium-dependent relaxation is preserved. The aim of this study was to investigate how endothelium-dependent relaxation is maintained in the early stages of type 1 diabetes. Diabetes was induced in Sprague-Dawley rats with a single injection of streptozotocin (48 mg/kg, i.v.), and after 6 weeks, endothelium-dependent and endothelium-independent relaxations were examined in the thoracic aorta in vitro. Lucigenin-enhanced chemiluminescence was used to measure superoxide generation from the aorta. Diabetes increased superoxide generation by the aorta (2,180 ± 363 vs 986 ± 163 AU/mg dry tissue weight). Acetylcholine (ACh)-induced relaxation was similar in aortae from control (pEC(50) 7.36 ± 0.09, R (max) 95 ± 3 %) and diabetic rats (pEC(50) 7.33 ± 0.10, R (max) 88 ± 5 %). The ACh-induced relaxation was abolished by the combined presence of the nitric oxide synthase inhibitor N-nitro-L-arginine (L-NNA, 100 μM) and an inhibitor of soluble guanylate cyclase, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ, 10 μM) in control rats, but under the same conditions, the diabetic aortic rings showed significant relaxation to ACh (pEC(50) 6.75 ± 0.15, R (max) 25 ± 4 %, p < 0.05). In diabetic aortae, the addition of haemoglobin, which inactivates nitric oxide, to L-NNA + ODQ abolished the response to ACh. The addition of the potassium channel blockers, apamin and TRAM-34, to L-NNA + ODQ also abolished the relaxation response to ACh. Diabetes significantly elevated plasma total nitrite/nitrate and increased expression of endothelial nitric oxide synthase (eNOS) and calmodulin in aortae. These data indicate that after 6 weeks of diabetes, despite increased oxidant stress, endothelium-dependent relaxation is maintained due to the increased eNOS expression resulting in increased NO synthesis. In diabetic arteries, NO acts both through and independently of cGMP pathways to cause relaxation.
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Affiliation(s)
- A Joshi
- Department of Pharmacology, University of Melbourne, Melbourne, Victoria, Australia.
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35
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Behringer EJ, Socha MJ, Polo-Parada L, Segal SS. Electrical conduction along endothelial cell tubes from mouse feed arteries: confounding actions of glycyrrhetinic acid derivatives. Br J Pharmacol 2012; 166:774-87. [PMID: 22168386 DOI: 10.1111/j.1476-5381.2011.01814.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND AND PURPOSE Electrical conduction along endothelium of resistance vessels has not been determined independently of the influence of smooth muscle, surrounding tissue or blood. Two interrelated hypotheses were tested: (i) Intercellular conduction of electrical signals is manifest in endothelial cell (EC) tubes; and (ii) Inhibitors of gap junction channels (GJCs) have confounding actions on EC electrical and Ca(2+) signalling. EXPERIMENTAL APPROACH Intact EC tubes were isolated from abdominal muscle feed (superior epigastric) arteries of C57BL/6 mice. Hyperpolarization was initiated with indirect (ACh) and direct (NS309) stimulation of intermediate- and small-conductance Ca(2+) -activated K(+) channels (IK(Ca) /SK(Ca) ). Remote membrane potential (V(m) ) responses to intracellular current injection defined the length constant (λ) for electrical conduction. Dye coupling was evaluated following intracellular microinjection of propidium iodide. Intracellular Ca(2+) dynamics were determined using Fura-2 photometry. Carbenoxolone (CBX) or β-glycyrrhetinic acid (βGA) was used to investigate the role of GJCs. KEY RESULTS Steady-state V(m) of ECs was -25 mV. ACh and NS309 hyperpolarized ECs by -40 and -60 mV respectively. Electrical conduction decayed monoexponentially with distance (λ∼1.4 mm). Propidium iodide injected into one EC spread into surrounding ECs. CBX or βGA inhibited dye transfer, electrical conduction and EC hyperpolarization reversibly. Both agents elevated resting Ca(2+) while βGA inhibited responses to ACh. CONCLUSIONS AND IMPLICATIONS Individual cells were effectively coupled to each other within EC tubes. Inhibiting GJCs with glycyrrhetinic acid derivatives blocked hyperpolarization mediated by IK(Ca) /SK(Ca) channels, regardless of Ca(2+) signalling, obviating use of these agents in distinguishing key determinants of electrical conduction along the endothelium.
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Affiliation(s)
- Erik J Behringer
- Medical Pharmacology and Physiology, University of Missouri, Columbia, MO 65212, USA
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Kuiper EFE, Nelemans A, Luiten P, Nijholt I, Dolga A, Eisel U. K(Ca)2 and k(ca)3 channels in learning and memory processes, and neurodegeneration. Front Pharmacol 2012; 3:107. [PMID: 22701424 PMCID: PMC3372087 DOI: 10.3389/fphar.2012.00107] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Accepted: 05/19/2012] [Indexed: 11/13/2022] Open
Abstract
Calcium-activated potassium (KCa) channels are present throughout the central nervous system as well as many peripheral tissues. Activation of KCa channels contribute to maintenance of the neuronal membrane potential and was shown to underlie the afterhyperpolarization (AHP) that regulates action potential firing and limits the firing frequency of repetitive action potentials. Different subtypes of KCa channels were anticipated on the basis of their physiological and pharmacological profiles, and cloning revealed two well defined but phylogenetic distantly related groups of channels. The group subject of this review includes both the small conductance KCa2 channels (KCa2.1, KCa2.2, and KCa2.3) and the intermediate-conductance (KCa3.1) channel. These channels are activated by submicromolar intracellular Ca2+ concentrations and are voltage independent. Of all KCa channels only the KCa2 channels can be potently but differentially blocked by the bee-venom apamin. In the past few years modulation of KCa channel activation revealed new roles for KCa2 channels in controlling dendritic excitability, synaptic functioning, and synaptic plasticity. Furthermore, KCa2 channels appeared to be involved in neurodegeneration, and learning and memory processes. In this review, we focus on the role of KCa2 and KCa3 channels in these latter mechanisms with emphasis on learning and memory, Alzheimer’s disease and on the interplay between neuroinflammation and different neurotransmitters/neuromodulators, their signaling components and KCa channel activation.
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Affiliation(s)
- Els F E Kuiper
- Molecular Neurobiology, University of Groningen Groningen, Netherlands
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Kerr PM, Tam R, Narang D, Potts K, McMillan D, McMillan K, Plane F. Endothelial calcium-activated potassium channels as therapeutic targets to enhance availability of nitric oxide. Can J Physiol Pharmacol 2012; 90:739-52. [PMID: 22626011 DOI: 10.1139/y2012-075] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The vascular endothelium plays a critical role in vascular health by controlling arterial diameter, regulating local cell growth, and protecting blood vessels from the deleterious consequences of platelet aggregation and activation of inflammatory responses. Circulating chemical mediators and physical forces act directly on the endothelium to release diffusible relaxing factors, such as nitric oxide (NO), and to elicit hyperpolarization of the endothelial cell membrane potential, which can spread to the surrounding smooth muscle cells via gap junctions. Endothelial hyperpolarization, mediated by activation of calcium-activated potassium (K(Ca)) channels, has generally been regarded as a distinct pathway for smooth muscle relaxation. However, recent evidence supports a role for endothelial K(Ca) channels in production of endothelium-derived NO, and indicates that pharmacological activation of these channels can enhance NO-mediated responses. In this review we summarize the current data on the functional role of endothelial K(Ca) channels in regulating NO-mediated changes in arterial diameter and NO production, and explore the tempting possibility that these channels may represent a novel avenue for therapeutic intervention in conditions associated with reduced NO availability such as hypertension, hypercholesterolemia, smoking, and diabetes mellitus.
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Affiliation(s)
- Paul M Kerr
- Department of Pharmacology, 9-62 Medical Sciences Building, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
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Bohlen HG. Rapid and slow nitric oxide responses during conducted vasodilation in the in vivo intestine and brain cortex microvasculatures. Microcirculation 2012; 18:623-34. [PMID: 22098301 DOI: 10.1111/j.1549-8719.2011.00127.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Conduction of arteriolar vasodilation is initiated by activation of nitric oxide (NO) mechanisms, but dependent on conduction of hyperpolarization. Most studies have used brief (<1 second) activation of the initial vasodilation to evaluate the fast conduction processes. However, most arteriolar mechanisms involving NO production persist for minutes. In this study, fast and slower components of arteriolar conduction in the in vivo rat brain and small intestine were compared using three-minute stimulation of NO-dependent vasodilation and measurement of [NO] at the distal sites. Within 10-15 seconds, both vasculatures had a rapidly conducted vasodilation and dilation at distance had a fast but small [NO] component. A slower but larger distal vasodilation occurred after 60-90 seconds in the intestine, but not the brain, and was associated with a substantial increase in [NO]. This slowly developed dilation appeared to be caused by flow mediated responses of larger arterioles as smaller arterioles dilated to lower downstream resistance. These results indicate while the intestinal and cerebral arterioles have a fast conducted vasodilation system, the intestinal arterioles also have a slower but larger dilation of major arterioles that is NO related and dependent on the conduction of vasodilation between small arterioles.
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Affiliation(s)
- H Glenn Bohlen
- Department of Cellular and Integrative Physiology, Indiana University Medical School, Indianapolis, Indiana 46202, USA.
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Kvietys PR, Granger DN. Role of reactive oxygen and nitrogen species in the vascular responses to inflammation. Free Radic Biol Med 2012; 52:556-592. [PMID: 22154653 PMCID: PMC3348846 DOI: 10.1016/j.freeradbiomed.2011.11.002] [Citation(s) in RCA: 213] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2011] [Revised: 11/04/2011] [Accepted: 11/04/2011] [Indexed: 12/23/2022]
Abstract
Inflammation is a complex and potentially life-threatening condition that involves the participation of a variety of chemical mediators, signaling pathways, and cell types. The microcirculation, which is critical for the initiation and perpetuation of an inflammatory response, exhibits several characteristic functional and structural changes in response to inflammation. These include vasomotor dysfunction (impaired vessel dilation and constriction), the adhesion and transendothelial migration of leukocytes, endothelial barrier dysfunction (increased vascular permeability), blood vessel proliferation (angiogenesis), and enhanced thrombus formation. These diverse responses of the microvasculature largely reflect the endothelial cell dysfunction that accompanies inflammation and the central role of these cells in modulating processes as varied as blood flow regulation, angiogenesis, and thrombogenesis. The importance of endothelial cells in inflammation-induced vascular dysfunction is also predicated on the ability of these cells to produce and respond to reactive oxygen and nitrogen species. Inflammation seems to upset the balance between nitric oxide and superoxide within (and surrounding) endothelial cells, which is necessary for normal vessel function. This review is focused on defining the molecular targets in the vessel wall that interact with reactive oxygen species and nitric oxide to produce the characteristic functional and structural changes that occur in response to inflammation. This analysis of the literature is consistent with the view that reactive oxygen and nitrogen species contribute significantly to the diverse vascular responses in inflammation and supports efforts that are directed at targeting these highly reactive species to maintain normal vascular health in pathological conditions that are associated with acute or chronic inflammation.
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Affiliation(s)
- Peter R Kvietys
- College of Medicine, Alfaisal University, Riyadh, Saudi Arabia
| | - D Neil Granger
- Department of Molecular & Cellular Physiology, Louisiana State University Health Sciences Center, Shreveport, LA 71130-3932, USA.
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Climent B, Schubert R, Stankevicius E, García-Sacristán A, Simonsen U, Rivera L. Large conductance Ca2+-activated K+ channels modulate endothelial cell outward currents and nitric oxide release in the intact rat superior mesenteric artery. Biochem Biophys Res Commun 2011; 417:1007-13. [PMID: 22209788 DOI: 10.1016/j.bbrc.2011.12.076] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Accepted: 12/15/2011] [Indexed: 11/26/2022]
Abstract
Endothelial cells (EC) control vascular smooth muscle cell (VSMC) tone by release of paracrine factors. VSMC may also influence the EC layer, and therefore, the present study hypothesized that the opening of large-conductance Ca(2+) activated K(+) (BK(Ca)) channels may indirectly modulate EC hyperpolarization and nitric oxide (NO) release via myoendothelial gap junctions (MEGJ). To address this hypothesis 'in situ' EC ion current recordings, isolated VSMC patch clamp recordings, and simultaneous measurements of NO concentration and relaxation were conducted using segments of the rat superior mesenteric artery. In arteries constricted by α(1)-adrenoceptor activation, ACh (1 μM) evoked EC outward currents, vasorelaxation, and NO release. In contrast to preincubation with iberiotoxin (IbTx, 100nM) application of IbTx after ACh decreased EC outward currents, NO release and vasorelaxation. Furthermore, in phenylephrine (Phe)-contracted arteries treated with a gap junction uncoupler, cabenoxolone (CBX), IbTx failed to decrease ACh-evoked EC outward currents. In addition, CBX decreased EC outward currents, time constant of the capacitative transients, input capacitance, and increased input resistance. In isolated VSMC CBX did not affect BK(Ca) currents. Immunohistochemistry revealed only BK(Ca) channel positive staining in the VSMC layer. Therefore, the present results suggest that BK(Ca) channels are expressed in the VSMC, and that Phe by activation of VSMC BK(Ca) channels modulates ACh-evoked EC outward currents, NO release and vasorelaxation via MEGJ in rat superior mesenteric artery.
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Affiliation(s)
- Belén Climent
- Departamento de Fisiología, Facultad de Farmacia, Universidad Complutense de Madrid, Spain.
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Stankevicius E, Dalsgaard T, Kroigaard C, Beck L, Boedtkjer E, Misfeldt MW, Nielsen G, Schjorring O, Hughes A, Simonsen U. Opening of small and intermediate calcium-activated potassium channels induces relaxation mainly mediated by nitric-oxide release in large arteries and endothelium-derived hyperpolarizing factor in small arteries from rat. J Pharmacol Exp Ther 2011; 339:842-50. [PMID: 21880870 DOI: 10.1124/jpet.111.179242] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
This study was designed to investigate whether calcium-activated potassium channels of small (SK(Ca) or K(Ca)2) and intermediate (IK(Ca) or K(Ca)3.1) conductance activated by 6,7-dichloro-1H-indole-2,3-dione 3-oxime (NS309) are involved in both nitric oxide (NO) and endothelium-derived hyperpolarizing factor (EDHF)-type relaxation in large and small rat mesenteric arteries. Segments of rat superior and small mesenteric arteries were mounted in myographs for functional studies. NO was recorded using NO microsensors. SK(Ca) and IK(Ca) channel currents and mRNA expression were investigated in human umbilical vein endothelial cells (HUVECs), and calcium concentrations were investigated in both HUVECs and mesenteric arterial endothelial cells. In both superior (∼1093 μm) and small mesenteric (∼300 μm) arteries, NS309 evoked endothelium- and concentration-dependent relaxations. In superior mesenteric arteries, NS309 relaxations and NO release were inhibited by both N(G),N(G)-asymmetric dimethyl-l-arginine (ADMA) (300 μM), an inhibitor of NO synthase, and apamin (0.5 μM) plus 1-[(2-chlorophenyl)diphenylmethyl]-1H-pyrazole (TRAM-34) (1 μM), blockers of SK(Ca) and IK(Ca) channels, respectively. In small mesenteric arteries, NS309 relaxations were reduced slightly by ADMA, whereas apamin plus an IK(Ca) channel blocker almost abolished relaxation. Iberiotoxin did not change NS309 relaxation. HUVECs expressed mRNA for SK(Ca) and IK(Ca) channels, and NS309 induced increases in calcium, outward current, and NO release that were blocked by apamin and TRAM-34 or charybdotoxin. These findings suggest that opening of SK(Ca) and IK(Ca) channels leads to endothelium-dependent relaxation that is mediated mainly by NO in large mesenteric arteries and by EDHF-type relaxation in small mesenteric arteries. NS309-induced calcium influx appears to contribute to the formation of NO.
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Affiliation(s)
- Edgaras Stankevicius
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Faculty of Health Sciences, Aarhus University, 8000 Aarhus C, Denmark
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Haddock RE, Grayson TH, Morris MJ, Howitt L, Chadha PS, Sandow SL. Diet-induced obesity impairs endothelium-derived hyperpolarization via altered potassium channel signaling mechanisms. PLoS One 2011; 6:e16423. [PMID: 21283658 PMCID: PMC3025034 DOI: 10.1371/journal.pone.0016423] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2010] [Accepted: 12/15/2010] [Indexed: 11/20/2022] Open
Abstract
Background The vascular endothelium plays a critical role in the control of blood flow. Altered endothelium-mediated vasodilator and vasoconstrictor mechanisms underlie key aspects of cardiovascular disease, including those in obesity. Whilst the mechanism of nitric oxide (NO)-mediated vasodilation has been extensively studied in obesity, little is known about the impact of obesity on vasodilation to the endothelium-derived hyperpolarization (EDH) mechanism; which predominates in smaller resistance vessels and is characterized in this study. Methodology/Principal Findings Membrane potential, vessel diameter and luminal pressure were recorded in 4th order mesenteric arteries with pressure-induced myogenic tone, in control and diet-induced obese rats. Obesity, reflecting that of human dietary etiology, was induced with a cafeteria-style diet (∼30 kJ, fat) over 16–20 weeks. Age and sexed matched controls received standard chow (∼12 kJ, fat). Channel protein distribution, expression and vessel morphology were determined using immunohistochemistry, Western blotting and ultrastructural techniques. In control and obese rat vessels, acetylcholine-mediated EDH was abolished by small and intermediate conductance calcium-activated potassium channel (SKCa/IKCa) inhibition; with such activity being impaired in obesity. SKCa-IKCa activation with cyclohexyl-[2-(3,5-dimethyl-pyrazol-1-yl)-6-methyl-pyrimidin-4-yl]-amine (CyPPA) and 1-ethyl-2-benzimidazolinone (1-EBIO), respectively, hyperpolarized and relaxed vessels from control and obese rats. IKCa-mediated EDH contribution was increased in obesity, and associated with altered IKCa distribution and elevated expression. In contrast, the SKCa-dependent-EDH component was reduced in obesity. Inward-rectifying potassium channel (Kir) and Na+/K+-ATPase inhibition by barium/ouabain, respectively, attenuated and abolished EDH in arteries from control and obese rats, respectively; reflecting differential Kir expression and distribution. Although changes in medial properties occurred, obesity had no effect on myoendothelial gap junction density. Conclusion/Significance In obese rats, vasodilation to EDH is impaired due to changes in the underlying potassium channel signaling mechanisms. Whilst myoendothelial gap junction density is unchanged in arteries of obese compared to control, increased IKCa and Na+/K+-ATPase, and decreased Kir underlie changes in the EDH mechanism.
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Affiliation(s)
- Rebecca E. Haddock
- Department of Pharmacology, School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia
- Department of Neuroscience, John Curtin School of Medical Research, Australian National University, Canberra, Australian Capital Territory, Australia
- * E-mail: (REH); (SLS)
| | - T. Hilton Grayson
- Department of Pharmacology, School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Margaret J. Morris
- Department of Pharmacology, School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Lauren Howitt
- Department of Pharmacology, School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Preet S. Chadha
- Department of Pharmacology, School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Shaun L. Sandow
- Department of Pharmacology, School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia
- * E-mail: (REH); (SLS)
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