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Sallam NA, Wang B, Laher I. Exercise training and vascular heterogeneity in db/db mice: evidence for regional- and duration-dependent effects. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2024; 397:2421-2436. [PMID: 37843589 DOI: 10.1007/s00210-023-02775-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Accepted: 10/04/2023] [Indexed: 10/17/2023]
Abstract
Exercise training (ET) has several health benefits; however, our understanding of regional adaptations to ET is limited. We examined the functional and molecular adaptations to short- and long-term ET in elastic and muscular conduit arteries of db/db mice in relation to changes in cardiovascular risk factors. Diabetic mice and their controls were exercised at moderate intensity for 4 or 8 weeks. The vasodilatory and contractile responses of thoracic aortae and femoral arteries isolated from the same animals were examined. Blood and aortic samples were used to measure hyperglycemia, oxidative stress, inflammation, dyslipidemia, protein expression of SOD isoforms, COX, eNOS, and Akt. Short-term ET improved nitric oxide (NO) mediated vasorelaxation in the aortae and femoral arteries of db/db mice in parallel with increased SOD2 and SOD3 expression, reduced oxidative stress and triglycerides, and independent of weight loss, glycemia, or inflammation. Long-term ET reduced body weight in parallel with reduced systemic inflammation and improved insulin sensitivity along with increased SOD1, Akt, and eNOS expression and improved NO vasorelaxation. Exercise did not restore NOS- and COX-independent vasodilatation in femoral arteries, nor did it mitigate the hypercontractility in the aortae of db/db mice; rather ET transiently increased contractility in association with upregulated COX-2. Long-term ET differentially affected the aortae and femoral arteries contractile responses. ET improved NO-mediated vasodilation in both arteries likely due to collective systemic effects. ET did not mitigate all diabetes-induced vasculopathies. Optimization of the ET regimen can help develop comprehensive management of type 2 diabetes.
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Affiliation(s)
- Nada A Sallam
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Cairo University, Cairo, 11562, Egypt
| | - Baohua Wang
- Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, BC, V6T1Z4, Canada
| | - Ismail Laher
- Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, BC, V6T1Z4, Canada.
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2
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Shin S, Park J, Choi HY, Lee K. Hypotensive and Endothelium-Dependent Vasorelaxant Effects of Grayblue Spicebush Ethanol Extract in Rats. Foods 2023; 12:4282. [PMID: 38231748 DOI: 10.3390/foods12234282] [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: 11/03/2023] [Revised: 11/21/2023] [Accepted: 11/26/2023] [Indexed: 01/19/2024] Open
Abstract
Hypertension is one of the most common chronic diseases, and its prevalence is increasing worldwide. Lindera glauca (Siebold & Zucc.) Blume, known as grayblue spicebush (GS), has been used as food and for medicinal purposes; however, studies about its hypotensive or vasorelaxant effects are lacking. Therefore, the hypotensive effect of an ethanolic extract of the GS branch (GSE) was investigated in 15-week-old spontaneously hypertensive rats (SHRs) using the tail cuff method. The GSE administration group (1000 mg/kg SHR body weight) showed a decrease in their systolic and diastolic blood pressure measured 4 h after its administration. In addition, we investigated its vasorelaxant effect using the thoracic aorta dissected from Sprague-Dawley rats. The GSE (0.5, 1, 2, 5, 10, and 20 μg/mL) showed an endothelium-dependent vasorelaxant effect, and its mechanisms were found to be relevant to the inward rectifier, voltage-dependent, and non-selective K+ channels. Moreover, the GSE (20 μg/mL) showed an inhibitory effect on aortic rings constricted with angiotensin II. Considering its hypotensive and vasorelaxant effects, GSE has potential as a functional food to help treat and prevent high blood pressure. However, further studies on the identification of the active components of GSE and safety evaluations of its use are needed.
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Affiliation(s)
- Sujin Shin
- Department of Korean Medicine, Graduate School, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Junkyu Park
- Department of Science in Korean Medicine, Graduate School, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Ho-Young Choi
- Department of Herbal Pharmacology, College of Korean Medicine, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Kyungjin Lee
- Department of Herbal Pharmacology, College of Korean Medicine, Kyung Hee University, Seoul 02447, Republic of Korea
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3
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Jung J, Shin S, Park J, Lee K, Choi HY. Hypotensive and Vasorelaxant Effects of Sanguisorbae Radix Ethanol Extract in Spontaneously Hypertensive and Sprague Dawley Rats. Nutrients 2023; 15:4510. [PMID: 37960162 PMCID: PMC10647409 DOI: 10.3390/nu15214510] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Revised: 10/21/2023] [Accepted: 10/23/2023] [Indexed: 11/15/2023] Open
Abstract
Hypertension requires proper management because of the increased risk of cardiovascular disease and death. For this purpose, functional foods containing tannins have been considered an effective treatment. Sanguisorbae radix (SR) also contains various tannins; however, there have been no studies on its vasorelaxant or antihypertensive effects. In this study, the vasorelaxant effect of the ethanol extract of SR (SRE) was investigated in the thoracic aorta of Sprague Dawley rats. SRE (1, 3, 10, 30, and 100 μg/mL) showed this effect in a dose-dependent manner, and its mechanisms were related to the NO/cGMP pathway and voltage-gated K+ channels. Concentrations of 300 and 1000 μg/mL blocked the influx of extracellular Ca2+ and inhibited vasoconstriction. Moreover, 100 μg/mL of SRE showed a relaxing effect on blood vessels constricted by angiotensin II. The hypotensive effect of SRE was investigated in spontaneously hypertensive rats (SHR) using the tail-cuff method. Blood pressure significantly decreased 4 and 8 h after 1000 mg/kg of SRE administration. Considering these hypotensive effects and the vasorelaxant mechanisms of SRE, our findings suggests that SRE can be used as a functional food to prevent and treat hypertension. Further studies are needed for identifying the active components and determining the optimal dosage.
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Affiliation(s)
- Jaesung Jung
- Department of Korean Medicine, Graduate School, Kyung Hee University, Seoul 02447, Republic of Korea; (J.J.); (S.S.)
| | - Sujin Shin
- Department of Korean Medicine, Graduate School, Kyung Hee University, Seoul 02447, Republic of Korea; (J.J.); (S.S.)
| | - Junkyu Park
- Department of Science in Korean Medicine, Graduate School, Kyung Hee University, Seoul 02447, Republic of Korea;
| | - Kyungjin Lee
- Department of Herbal Pharmacology, College of Korean Medicine, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Ho-Young Choi
- Department of Herbal Pharmacology, College of Korean Medicine, Kyung Hee University, Seoul 02447, Republic of Korea
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4
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Paulo M, Costa DEFR, Bonaventura D, Lunardi CN, Bendhack LM. Nitric Oxide Donors as Potential Drugs for the Treatment of Vascular Diseases Due to Endothelium Dysfunction. Curr Pharm Des 2021; 26:3748-3759. [PMID: 32427079 DOI: 10.2174/1381612826666200519114442] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Accepted: 04/07/2020] [Indexed: 11/22/2022]
Abstract
Endothelial dysfunction and consequent vasoconstriction are a common condition in patients with hypertension and other cardiovascular diseases. Endothelial cells produce and release vasodilator substances that play a pivotal role in normal vascular tone. The mechanisms underlying endothelial dysfunction are multifactorial. However, enhanced reactive oxygen species (ROS) production and consequent vasoconstriction instead of endothelium-derived relaxant generation and consequent vasodilatation contribute to this dysfunction considerably. The main targets of the drugs that are currently used to treat vascular diseases concerning enzyme activities and protein functions that are impaired by endothelial nitric oxide synthase (eNOS) uncoupling and ROS production. Nitric oxide (NO) bioavailability can decrease due to deficient NO production by eNOS and/or NO release to vascular smooth muscle cells, which impairs endothelial function. Considering the NO cellular mechanisms, tackling the issue of eNOS uncoupling could avoid endothelial dysfunction: provision of the enzyme cofactor tetrahydrobiopterin (BH4) should elicit NO release from NO donors, to activate soluble guanylyl cyclase. This should increase cyclic guanosine-monophosphate (cGMP) generation and inhibit phosphodiesterases (especially PDE5) that selectively degrade cGMP. Consequently, protein kinase-G should be activated, and K+ channels should be phosphorylated and activated, which is crucial for cell membrane hyperpolarization and vasodilation and/or inhibition of ROS production. The present review summarizes the current concepts about the vascular cellular mechanisms that underlie endothelial dysfunction and which could be the target of drugs for the treatment of patients with cardiovascular disease.
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Affiliation(s)
- Michele Paulo
- Department Physics and Chemistry, Faculty of Pharmaceutical Sciences of Ribeirao Preto- University of Sao Paulo Av. Do Cafe SN, Brazil
| | - Daniela E F R Costa
- Department of Pharmacology, Biological Sciences Institute, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Daniella Bonaventura
- Department of Pharmacology, Biological Sciences Institute, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Claure N Lunardi
- Laboratory of Photochemistry and Nanobiotechnology, University of Brasilia, Brasilia, Brazil
| | - Lusiane M Bendhack
- Department Physics and Chemistry, Faculty of Pharmaceutical Sciences of Ribeirao Preto- University of Sao Paulo Av. Do Cafe SN, Brazil
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Hydrogen Sulfide Relaxes Human Uterine Artery via Activating Smooth Muscle BK Ca Channels. Antioxidants (Basel) 2020; 9:antiox9111127. [PMID: 33202933 PMCID: PMC7697977 DOI: 10.3390/antiox9111127] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 10/29/2020] [Accepted: 11/06/2020] [Indexed: 12/16/2022] Open
Abstract
Opening of large conductance calcium-activated and voltage-dependent potassium (BKCa) channels hyperpolarizes plasma membranes of smooth muscle (SM) to cause vasodilation, underling a key mechanism for mediating uterine artery (UA) dilation in pregnancy. Hydrogen sulfide (H2S) has been recently identified as a new UA vasodilator, yet the mechanism underlying H2S-induced UA dilation is unknown. Here, we tested whether H2S activated BKCa channels in human UA smooth muscle cells (hUASMC) to mediate UA relaxation. Multiple BKCa subunits were found in human UA in vitro and hUASMC in vitro, and high β1 and γ1 proteins were localized in SM cells in human UA. Baseline outward currents, recorded by whole-cell and single-channel patch clamps, were significantly inhibited by specific BKCa blockers iberiotoxin (IBTX) or tetraethylammonium, showing specific BKCa activity in hUASMC. H2S dose (NaHS, 1–1000 µM)-dependently potentiated BKCa currents and open probability. Co-incubation with a Ca2+ blocker nifedipine (5 µM) or a chelator (ethylene glycol-bis (β-aminoethyl ether)-N,N,N′,N′-tetraacetic acid (EGTA), 5 mM) did not alter H2S-potentiated BKCa currents and open probability. NaHS also dose-dependently relaxed phenylephrine pre-constricted freshly prepared human UA rings, which was inhibited by IBTX. Thus, H2S stimulated human UA relaxation at least partially via activating SM BKCa channels independent of extracellular Ca2+.
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Dasgupta A, Wu D, Tian L, Xiong PY, Dunham-Snary KJ, Chen KH, Alizadeh E, Motamed M, Potus F, Hindmarch CCT, Archer SL. Mitochondria in the Pulmonary Vasculature in Health and Disease: Oxygen-Sensing, Metabolism, and Dynamics. Compr Physiol 2020; 10:713-765. [PMID: 32163206 DOI: 10.1002/cphy.c190027] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
In lung vascular cells, mitochondria serve a canonical metabolic role, governing energy homeostasis. In addition, mitochondria exist in dynamic networks, which serve noncanonical functions, including regulation of redox signaling, cell cycle, apoptosis, and mitochondrial quality control. Mitochondria in pulmonary artery smooth muscle cells (PASMC) are oxygen sensors and initiate hypoxic pulmonary vasoconstriction. Acquired dysfunction of mitochondrial metabolism and dynamics contribute to a cancer-like phenotype in pulmonary arterial hypertension (PAH). Acquired mitochondrial abnormalities, such as increased pyruvate dehydrogenase kinase (PDK) and pyruvate kinase muscle isoform 2 (PKM2) expression, which increase uncoupled glycolysis (the Warburg phenomenon), are implicated in PAH. Warburg metabolism sustains energy homeostasis by the inhibition of oxidative metabolism that reduces mitochondrial apoptosis, allowing unchecked cell accumulation. Warburg metabolism is initiated by the induction of a pseudohypoxic state, in which DNA methyltransferase (DNMT)-mediated changes in redox signaling cause normoxic activation of HIF-1α and increase PDK expression. Furthermore, mitochondrial division is coordinated with nuclear division through a process called mitotic fission. Increased mitotic fission in PAH, driven by increased fission and reduced fusion favors rapid cell cycle progression and apoptosis resistance. Downregulation of the mitochondrial calcium uniporter complex (MCUC) occurs in PAH and is one potential unifying mechanism linking Warburg metabolism and mitochondrial fission. Mitochondrial metabolic and dynamic disorders combine to promote the hyperproliferative, apoptosis-resistant, phenotype in PAH PASMC, endothelial cells, and fibroblasts. Understanding the molecular mechanism regulating mitochondrial metabolism and dynamics has permitted identification of new biomarkers, nuclear and CT imaging modalities, and new therapeutic targets for PAH. © 2020 American Physiological Society. Compr Physiol 10:713-765, 2020.
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Affiliation(s)
- Asish Dasgupta
- Department of Medicine, Queen's University, Kingston, Ontario, Canada
| | - Danchen Wu
- Department of Medicine, Queen's University, Kingston, Ontario, Canada
| | - Lian Tian
- Department of Medicine, Queen's University, Kingston, Ontario, Canada
| | - Ping Yu Xiong
- Department of Medicine, Queen's University, Kingston, Ontario, Canada
| | | | - Kuang-Hueih Chen
- Department of Medicine, Queen's University, Kingston, Ontario, Canada
| | - Elahe Alizadeh
- Department of Medicine, Queen's Cardiopulmonary Unit (QCPU), Translational Institute of Medicine (TIME), Queen's University, Kingston, Ontario, Canada
| | - Mehras Motamed
- Department of Medicine, Queen's University, Kingston, Ontario, Canada
| | - François Potus
- Department of Medicine, Queen's University, Kingston, Ontario, Canada
| | - Charles C T Hindmarch
- Department of Medicine, Queen's Cardiopulmonary Unit (QCPU), Translational Institute of Medicine (TIME), Queen's University, Kingston, Ontario, Canada
| | - Stephen L Archer
- Department of Medicine, Queen's University, Kingston, Ontario, Canada.,Kingston Health Sciences Centre, Kingston, Ontario, Canada.,Providence Care Hospital, Kingston, Ontario, Canada
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7
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Babicheva A, Ayon RJ, Zhao T, Ek Vitorin JF, Pohl NM, Yamamura A, Yamamura H, Quinton BA, Ba M, Wu L, Ravellette KS, Rahimi S, Balistrieri F, Harrington A, Vanderpool RR, Thistlethwaite PA, Makino A, Yuan JXJ. MicroRNA-mediated downregulation of K + channels in pulmonary arterial hypertension. Am J Physiol Lung Cell Mol Physiol 2020; 318:L10-L26. [PMID: 31553627 PMCID: PMC6985878 DOI: 10.1152/ajplung.00010.2019] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Revised: 08/19/2019] [Accepted: 09/06/2019] [Indexed: 12/22/2022] Open
Abstract
Downregulated expression of K+ channels and decreased K+ currents in pulmonary artery smooth muscle cells (PASMC) have been implicated in the development of sustained pulmonary vasoconstriction and vascular remodeling in patients with idiopathic pulmonary arterial hypertension (IPAH). However, it is unclear exactly how K+ channels are downregulated in IPAH-PASMC. MicroRNAs (miRNAs) are small non-coding RNAs that are capable of posttranscriptionally regulating gene expression by binding to the 3'-untranslated regions of their targeted mRNAs. Here, we report that specific miRNAs are responsible for the decreased K+ channel expression and function in IPAH-PASMC. We identified 3 miRNAs (miR-29b, miR-138, and miR-222) that were highly expressed in IPAH-PASMC in comparison to normal PASMC (>2.5-fold difference). Selectively upregulated miRNAs are correlated with the decreased expression and attenuated activity of K+ channels. Overexpression of miR-29b, miR-138, or miR-222 in normal PASMC significantly decreased whole cell K+ currents and downregulated voltage-gated K+ channel 1.5 (KV1.5/KCNA5) in normal PASMC. Inhibition of miR-29b in IPAH-PASMC completely recovered K+ channel function and KV1.5 expression, while miR-138 and miR-222 had a partial or no effect. Luciferase assays further revealed that KV1.5 is a direct target of miR-29b. Additionally, overexpression of miR-29b in normal PASMC decreased large-conductance Ca2+-activated K+ (BKCa) channel currents and downregulated BKCa channel β1 subunit (BKCaβ1 or KCNMB1) expression, while inhibition of miR-29b in IPAH-PASMC increased BKCa channel activity and BKCaβ1 levels. These data indicate upregulated miR-29b contributes at least partially to the attenuated function and expression of KV and BKCa channels in PASMC from patients with IPAH.
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Affiliation(s)
- Aleksandra Babicheva
- Section of Physiology, Division of Pulmonary, Critical Care and Sleep Medicine, University of California, San Diego, La Jolla, California
- Departments of Medicine and Physiology, The University of Arizona, Tucson, Arizona
| | - Ramon J Ayon
- Departments of Medicine and Physiology, The University of Arizona, Tucson, Arizona
| | - Tengteng Zhao
- Section of Physiology, Division of Pulmonary, Critical Care and Sleep Medicine, University of California, San Diego, La Jolla, California
- Departments of Medicine and Physiology, The University of Arizona, Tucson, Arizona
| | - Jose F Ek Vitorin
- Departments of Medicine and Physiology, The University of Arizona, Tucson, Arizona
| | - Nicole M Pohl
- Department of Medicine, University of Illinois at Chicago, Chicago, Illinois
| | - Aya Yamamura
- Kinjo Gakuin University School of Pharmacy, Nagoya, Japan
| | - Hisao Yamamura
- Nagoya City University Graduate School of Pharmaceutical Sciences, Nagoya, Japan
| | - Brooke A Quinton
- Departments of Medicine and Physiology, The University of Arizona, Tucson, Arizona
| | - Manqing Ba
- Departments of Medicine and Physiology, The University of Arizona, Tucson, Arizona
| | - Linda Wu
- Departments of Medicine and Physiology, The University of Arizona, Tucson, Arizona
| | - Keeley S Ravellette
- Departments of Medicine and Physiology, The University of Arizona, Tucson, Arizona
| | - Shamin Rahimi
- Section of Physiology, Division of Pulmonary, Critical Care and Sleep Medicine, University of California, San Diego, La Jolla, California
| | - Francesca Balistrieri
- Section of Physiology, Division of Pulmonary, Critical Care and Sleep Medicine, University of California, San Diego, La Jolla, California
| | - Angela Harrington
- Section of Physiology, Division of Pulmonary, Critical Care and Sleep Medicine, University of California, San Diego, La Jolla, California
| | - Rebecca R Vanderpool
- Departments of Medicine and Physiology, The University of Arizona, Tucson, Arizona
| | | | - Ayako Makino
- Division of Endocrinology and Metabolism, Department of Medicine, University of California, San Diego, La Jolla, California
- Departments of Medicine and Physiology, The University of Arizona, Tucson, Arizona
| | - Jason X-J Yuan
- Section of Physiology, Division of Pulmonary, Critical Care and Sleep Medicine, University of California, San Diego, La Jolla, California
- Departments of Medicine and Physiology, The University of Arizona, Tucson, Arizona
- Department of Medicine, University of Illinois at Chicago, Chicago, Illinois
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Kakumanu R, Kuruppu S, Rash LD, Isbister GK, Hodgson WC, Kemp-Harper BK. D. russelii Venom Mediates Vasodilatation of Resistance Like Arteries via Activation of K v and K Ca Channels. Toxins (Basel) 2019; 11:E197. [PMID: 30939844 PMCID: PMC6520720 DOI: 10.3390/toxins11040197] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Revised: 03/17/2019] [Accepted: 03/28/2019] [Indexed: 11/16/2022] Open
Abstract
Russell's viper (Daboia russelii) venom causes a range of clinical effects in humans. Hypotension is an uncommon but severe complication of Russell's viper envenoming. The mechanism(s) responsible for this effect are unclear. In this study, we examined the cardiovascular effects of Sri Lankan D. russelii venom in anaesthetised rats and in isolated mesenteric arteries. D. russelii venom (100 μg/kg, i.v.) caused a 45 ± 8% decrease in blood pressure within 10 min of administration in anaesthetised (100 μg/kg ketamine/xylazine 10:1 ratio, i.p.) rats. Venom (1 ng/mL⁻1 μg/mL) caused concentration-dependent relaxation (EC50 = 145.4 ± 63.6 ng/mL, Rmax = 92 ± 2%) in U46619 pre-contracted rat small mesenteric arteries mounted in a myograph. Vasorelaxant potency of venom was unchanged in the presence of the nitric oxide synthase inhibitor, L-NAME (100 µM), or removal of the endothelium. In the presence of high K⁺ (30 mM), the vasorelaxant response to venom was abolished. Similarly, blocking voltage-dependent (Kv: 4-aminopryidine; 1000 µM) and Ca2+-activated (KCa: tetraethylammonium (TEA; 1000 µM); SKCa: apamin (0.1 µM); IKCa: TRAM-34 (1 µM); BKCa; iberiotoxin (0.1 µM)) K⁺ channels markedly attenuated venom-induced relaxation. Responses were unchanged in the presence of the ATP-sensitive K⁺ channel blocker glibenclamide (10 µM), or H1 receptor antagonist, mepyramine (0.1 µM). Venom-induced vasorelaxtion was also markedly decreased in the presence of the transient receptor potential cation channel subfamily V member 4 (TRPV4) antagonist, RN-1734 (10 µM). In conclusion, D. russelii-venom-induced hypotension in rodents may be due to activation of Kv and KCa channels, leading to vasorelaxation predominantly via an endothelium-independent mechanism. Further investigation is required to identify the toxin(s) responsible for this effect.
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Affiliation(s)
- Rahini Kakumanu
- Department of Pharmacology, Biomedicine Discovery Institute, Faculty of Medicine, Nursing & Health Sciences, Monash University, Clayton VIC 3800, Australia.
| | - Sanjaya Kuruppu
- Department of Biochemistry & Molecular Biology, Biomedicine Discovery Institute, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton VIC 3800, Australia.
| | - Lachlan D Rash
- Faculty of Medicine, School of Biomedical Sciences, The University of Queensland, St Lucia QLD 4072, Australia.
| | - Geoffrey K Isbister
- Clinical Toxicology Research Group, University of Newcastle, Callaghan NSW 2308, Australia.
| | - Wayne C Hodgson
- Department of Pharmacology, Biomedicine Discovery Institute, Faculty of Medicine, Nursing & Health Sciences, Monash University, Clayton VIC 3800, Australia.
| | - Barbara K Kemp-Harper
- Department of Pharmacology, Biomedicine Discovery Institute, Faculty of Medicine, Nursing & Health Sciences, Monash University, Clayton VIC 3800, Australia.
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Orlov SN, Gusakova SV, Smaglii LV, Koltsova SV, Sidorenko SV. Vasoconstriction triggered by hydrogen sulfide: Evidence for Na +,K +,2Cl -cotransport and L-type Ca 2+ channel-mediated pathway. Biochem Biophys Rep 2017; 12:220-227. [PMID: 29159314 PMCID: PMC5683885 DOI: 10.1016/j.bbrep.2017.09.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Revised: 08/30/2017] [Accepted: 09/27/2017] [Indexed: 11/19/2022] Open
Abstract
Objectives This study examined the dose-dependent actions of hydrogen sulfide donor sodium hydrosulphide (NaHS) on isometric contractions and ion transport in rat aorta smooth muscle cells (SMC). Methods Isometric contraction was measured in ring aortas segments from male Wistar rats. Activity of Na+/K+-pump and Na+,K+,2Cl-cotransport was measured in cultured endothelial and smooth muscle cells from the rat aorta as ouabain-sensitive and ouabain-resistant, bumetanide-sensitive components of the 86Rb influx, respectively. Results NaHS exhibited the bimodal action on contractions triggered by modest depolarization ([K+]o=30 mM). At 10-4 M, NaHS augmented contractions of intact and endothelium-denuded strips by ~ 15% and 25%, respectively, whereas at concentration of 10-3 M it decreased contractile responses by more than two-fold. Contractions evoked by 10-4 M NaHS were completely abolished by bumetanide, a potent inhibitor of Na+,K+,2Cl-cotransport, whereas the inhibition seen at 10-3 M NaHS was suppressed in the presence of K+ channel blocker TEA. In cultured SMC, 5×10-5 M NaHS increased Na+,K+,2Cl- - cotransport without any effect on the activity of this carrier in endothelial cells. In depolarized SMC, 45Ca influx was enhanced in the presence of 10-4 M NaHS and suppressed under elevation of [NaHS] up to 10-3 M. 45Ca influx triggered by 10-4 M NaHS was abolished by bumetanide and L-type Ca2+ channel blocker nicardipine. Conclusions Our results strongly suggest that contractions of rat aortic rings triggered by low doses of NaHS are mediated by activation of Na+,K+,2Cl-cotransport and Ca2+ influx via L-type channels.
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Key Words
- CO, carbon monoxide
- COX, cyclooxygenase
- CSE, cystathionine-γ-lyase
- Ca2+ influx
- Contraction
- EC, endothelial cells
- EDHF, endothelium-derived hyperpolarizing factor
- H2S, hydrogen sulfide
- Hydrogen sulfide
- KATP, ATP-sensitive potassium channels
- KCa, Ca2+-activated potassium channels
- NKCC, Na+,K+,2Cl- cotransport
- NO, nitric oxide
- Na+,K+,2Cl-cotransport
- NaHS, sodium hydrosulphide
- PE, phenylephrine
- PSS, physiologically-balanced salt solution
- RAEC, endothelial cells from rat aorta
- RASMC, smooth muscle cells from rat aorta
- Rat aorta
- SMC, smooth muscle cells
- Smooth muscle cells
- TEA, tetraethylammonium chloride
- VSMC, vascular smooth muscle cells
- VSMR, vascular smooth muscles from rat
- cGMP, cyclic guanosine monophosphate
- sGC, soluble guanylyl cyclase
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Affiliation(s)
- Sergei N. Orlov
- Central Research Laboratory, Siberian State Medical University, Moskovskiy trakt 2, Tomsk 634050, Russia
- Faculty of Biology MV Lomonosov Moscow State University, Leninskiye gory 1/12, Moscow 119991, Russia
- Corresponding author at: Faculty of Biology MV Lomonosov Moscow State University, Leninskiye gory 1/12, Moscow 119991, Russia.Faculty of Biology MV Lomonosov Moscow State UniversityLeninskiye gory 1/12Moscow119991Russia
| | - Svetlana V. Gusakova
- Department of Biophysics and Functional Diagnostics, Medical and Biological Faculty, Siberian State Medical University, Moskovskiy trakt 2, Tomsk 634050, Russia
- Corresponding author.
| | - Liudmila V. Smaglii
- Department of Biophysics and Functional Diagnostics, Medical and Biological Faculty, Siberian State Medical University, Moskovskiy trakt 2, Tomsk 634050, Russia
| | - Svetlana V. Koltsova
- Faculty of Biology MV Lomonosov Moscow State University, Leninskiye gory 1/12, Moscow 119991, Russia
| | - Svetalana V. Sidorenko
- Faculty of Biology MV Lomonosov Moscow State University, Leninskiye gory 1/12, Moscow 119991, Russia
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Tykocki NR, Boerman EM, Jackson WF. Smooth Muscle Ion Channels and Regulation of Vascular Tone in Resistance Arteries and Arterioles. Compr Physiol 2017; 7:485-581. [PMID: 28333380 DOI: 10.1002/cphy.c160011] [Citation(s) in RCA: 212] [Impact Index Per Article: 30.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Vascular tone of resistance arteries and arterioles determines peripheral vascular resistance, contributing to the regulation of blood pressure and blood flow to, and within the body's tissues and organs. Ion channels in the plasma membrane and endoplasmic reticulum of vascular smooth muscle cells (SMCs) in these blood vessels importantly contribute to the regulation of intracellular Ca2+ concentration, the primary determinant of SMC contractile activity and vascular tone. Ion channels provide the main source of activator Ca2+ that determines vascular tone, and strongly contribute to setting and regulating membrane potential, which, in turn, regulates the open-state-probability of voltage gated Ca2+ channels (VGCCs), the primary source of Ca2+ in resistance artery and arteriolar SMCs. Ion channel function is also modulated by vasoconstrictors and vasodilators, contributing to all aspects of the regulation of vascular tone. This review will focus on the physiology of VGCCs, voltage-gated K+ (KV) channels, large-conductance Ca2+-activated K+ (BKCa) channels, strong-inward-rectifier K+ (KIR) channels, ATP-sensitive K+ (KATP) channels, ryanodine receptors (RyRs), inositol 1,4,5-trisphosphate receptors (IP3Rs), and a variety of transient receptor potential (TRP) channels that contribute to pressure-induced myogenic tone in resistance arteries and arterioles, the modulation of the function of these ion channels by vasoconstrictors and vasodilators, their role in the functional regulation of tissue blood flow and their dysfunction in diseases such as hypertension, obesity, and diabetes. © 2017 American Physiological Society. Compr Physiol 7:485-581, 2017.
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Affiliation(s)
- Nathan R Tykocki
- Department of Pharmacology, University of Vermont, Burlington, Vermont, USA
| | - Erika M Boerman
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri, USA
| | - William F Jackson
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan, USA
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11
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Hypotensive effect and vascular relaxation in different arteries induced by the nitric oxide donor RuBPY. Nitric Oxide 2017; 62:11-16. [DOI: 10.1016/j.niox.2016.11.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Revised: 11/01/2016] [Accepted: 11/04/2016] [Indexed: 11/21/2022]
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12
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Novakovic A, Marinko M, Vranic A, Jankovic G, Milojevic P, Stojanovic I, Nenezic D, Ugresic N, Kanjuh V, Yang Q, He GW. Mechanisms underlying the vasorelaxation of human internal mammary artery induced by (-)-epicatechin. Eur J Pharmacol 2015; 762:306-12. [PMID: 26049011 DOI: 10.1016/j.ejphar.2015.05.066] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Revised: 05/03/2015] [Accepted: 05/21/2015] [Indexed: 02/05/2023]
Abstract
Evidences have suggested that flavanol compound (-)-epicatechin is associated with reduced risk of cardiovascular diseases. One of the mechanisms of its cardioprotective effect is vasodilation. However, the exact mechanisms by which (-)-epicatechin causes vasodilation are not yet clearly defined. The aims of the present study were to investigate relaxant effect of flavanol (-)-epicatechin on the isolated human internal mammary artery (HIMA) and to determine the mechanisms underlying its vasorelaxation. Our results showed that (-)-epicatechin induced a concentration-dependent relaxation of HIMA rings pre-contracted by phenylephrine. Among the K(+) channel blockers, 4-aminopyridine (4-AP) and margatoxin, blockers of voltage-gated K(+) (KV) channels, and glibenclamide, a selective ATP-sensitive K(+) (KATP) channels blocker, partly inhibited the (-)-epicatechin-induced relaxation of HIMA, while iberiotoxin, a most selective blocker of large conductance Ca(2+)-activated K(+) channels (BKCa), almost completely inhibited the relaxation. In rings pre-contracted by 80mM K(+), (-)-epicatechin induced partial relaxation of HIMA, whereas in Ca(2+)-free medium, (-)-epicatechin completely relaxed HIMA rings pre-contracted by phenylephrine and caffeine. Finally, thapsigargin, a sarcoplasmic reticulum Ca(2+)-ATPase inhibitor, slightly antagonized (-)-epicatechin-induced relaxation of HIMA pre-contracted by phenylephrine. These results suggest that (-)-epicatechin induces strong endothelium-independent relaxation of HIMA pre-contracted by phenylephrine whilst 4-AP- and margatoxin-sensitive KV channels, as well as BKCa and KATP channels, located in vascular smooth muscle, mediate this relaxation. In addition, it seems that (-)-epicatechin could inhibit influx of extracellular Ca(2+), interfere with intracellular Ca(2+) release and re-uptake by the sarcoplasmic reticulum.
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Affiliation(s)
- Aleksandra Novakovic
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Belgrade, Serbia.
| | - Marija Marinko
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Belgrade, Serbia
| | - Aleksandra Vranic
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Belgrade, Serbia
| | - Goran Jankovic
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Belgrade, Serbia
| | - Predrag Milojevic
- Faculty of Medicine, University of Belgrade, Belgrade, Serbia; Institute for Cardiovascular Diseases "Dedinje", Belgrade, Serbia
| | - Ivan Stojanovic
- Faculty of Medicine, University of Belgrade, Belgrade, Serbia; Institute for Cardiovascular Diseases "Dedinje", Belgrade, Serbia
| | - Dragoslav Nenezic
- Faculty of Medicine, University of Belgrade, Belgrade, Serbia; Institute for Cardiovascular Diseases "Dedinje", Belgrade, Serbia
| | - Nenad Ugresic
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Belgrade, Serbia
| | | | - Qin Yang
- Department of Surgery, The Chinese University of Hong Kong, Hong Kong; TEDA International Cardiovascular Hospital, Tianjin, China
| | - Guo-Wei He
- TEDA International Cardiovascular Hospital, Tianjin, China
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13
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Mills TA, Greenwood SL, Devlin G, Shweikh Y, Robinson M, Cowley E, Hayward CE, Cottrell EC, Tropea T, Brereton MF, Dalby-Brown W, Wareing M. Activation of KV7 channels stimulates vasodilatation of human placental chorionic plate arteries. Placenta 2015; 36:638-44. [PMID: 25862611 DOI: 10.1016/j.placenta.2015.03.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Revised: 03/12/2015] [Accepted: 03/14/2015] [Indexed: 02/01/2023]
Abstract
INTRODUCTION Potassium (K(+)) channels are key regulators of vascular smooth muscle cell (VSMC) excitability. In systemic small arteries, Kv7 channel expression/activity has been noted and a role in vascular tone regulation demonstrated. We aimed to demonstrate functional Kv7 channels in human fetoplacental small arteries. METHODS Human placental chorionic plate arteries (CPAs) were obtained at term. CPA responses to Kv7 channel modulators was determined by wire myography. Presence of Kv7 channel mRNA (encoded by KCNQ1-5) and protein expression were assessed by RT-PCR and immunohistochemistry/immunofluorescence, respectively. RESULTS Kv7 channel blockade with linopirdine increased CPA basal tone and AVP-induced contraction. Pre-contracted CPAs (AVP; 80 mM K(+) depolarization solution) exhibited significant relaxation to flupirtine, retigabine, the acrylamide (S)-1, and (S) BMS-204352, differential activators of Kv7.1 - Kv7.5 channels. All CPAs assessed expressed KCNQ1 and KCNQ3-5 mRNA; KCNQ2 was expressed only in a subset of CPAs. Kv7 protein expression was confirmed in intact CPAs and isolated VSMCs. DISCUSSION Kv7 channels are present and active in fetoplacental vessels, contributing to vascular tone regulation in normal pregnancy. Targeting these channels may represent a therapeutic intervention in pregnancies complicated by increased vascular resistance.
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Affiliation(s)
- T A Mills
- School of Nursing, Midwifery and Social Work, The University of Manchester, Jean McFarlane Building, Oxford Road, Manchester M13 9PL, United Kingdom.
| | - S L Greenwood
- Maternal and Fetal Health Research Centre, Institute of Human Development, The University of Manchester, Manchester Academic Health Science Centre, St. Mary's Hospital, Central Manchester University Hospitals NHS Foundation Trust, Manchester M13 9WL, United Kingdom.
| | - G Devlin
- Maternal and Fetal Health Research Centre, Institute of Human Development, The University of Manchester, Manchester Academic Health Science Centre, St. Mary's Hospital, Central Manchester University Hospitals NHS Foundation Trust, Manchester M13 9WL, United Kingdom.
| | - Y Shweikh
- Maternal and Fetal Health Research Centre, Institute of Human Development, The University of Manchester, Manchester Academic Health Science Centre, St. Mary's Hospital, Central Manchester University Hospitals NHS Foundation Trust, Manchester M13 9WL, United Kingdom
| | - M Robinson
- Maternal and Fetal Health Research Centre, Institute of Human Development, The University of Manchester, Manchester Academic Health Science Centre, St. Mary's Hospital, Central Manchester University Hospitals NHS Foundation Trust, Manchester M13 9WL, United Kingdom
| | - E Cowley
- Maternal and Fetal Health Research Centre, Institute of Human Development, The University of Manchester, Manchester Academic Health Science Centre, St. Mary's Hospital, Central Manchester University Hospitals NHS Foundation Trust, Manchester M13 9WL, United Kingdom.
| | - C E Hayward
- Maternal and Fetal Health Research Centre, Institute of Human Development, The University of Manchester, Manchester Academic Health Science Centre, St. Mary's Hospital, Central Manchester University Hospitals NHS Foundation Trust, Manchester M13 9WL, United Kingdom.
| | - E C Cottrell
- Maternal and Fetal Health Research Centre, Institute of Human Development, The University of Manchester, Manchester Academic Health Science Centre, St. Mary's Hospital, Central Manchester University Hospitals NHS Foundation Trust, Manchester M13 9WL, United Kingdom.
| | - T Tropea
- Maternal and Fetal Health Research Centre, Institute of Human Development, The University of Manchester, Manchester Academic Health Science Centre, St. Mary's Hospital, Central Manchester University Hospitals NHS Foundation Trust, Manchester M13 9WL, United Kingdom; Department of Biology, Ecology and Earth Sciences, University of Calabria, Arcavacata di Rende, CS, Italy.
| | - M F Brereton
- Maternal and Fetal Health Research Centre, Institute of Human Development, The University of Manchester, Manchester Academic Health Science Centre, St. Mary's Hospital, Central Manchester University Hospitals NHS Foundation Trust, Manchester M13 9WL, United Kingdom.
| | - W Dalby-Brown
- Pcovery Aps, Thorvaldsensvej 57, DK-1871 Frederiksberg C, Denmark.
| | - M Wareing
- Maternal and Fetal Health Research Centre, Institute of Human Development, The University of Manchester, Manchester Academic Health Science Centre, St. Mary's Hospital, Central Manchester University Hospitals NHS Foundation Trust, Manchester M13 9WL, United Kingdom.
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Lu Y, Zhong F, Wang X, Li H, Zhu Z, Kong X, Zhao J, Wu Q. Mechanism of motilin-mediated inhibition on voltage-dependent potassium currents in hippocampal neurons. Neuroscience 2014; 284:374-380. [PMID: 25168724 DOI: 10.1016/j.neuroscience.2014.08.020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Revised: 07/11/2014] [Accepted: 08/11/2014] [Indexed: 01/30/2023]
Abstract
OBJECTIVE The effects of motilin on voltage-dependent K+ currents in hippocampal neurons with the addition of L-arginine (L-AA), D-arginine (D-AA) and N-nitro-L-arginine methyl ester (L-NAME) were investigated in this study. METHODS Mice (1-3 days old) were randomly assigned to different groups according to the addition of motilin, L-AA, D-AA, and L-NAME. The K+ current signals were detected by the whole-cell patch-clamp technique. RESULTS Compared with the control group, the transient outward voltage-dependent K+ current was significantly inhibited by motilin added with L-AA. In contrast, the addition of motilin and L-NAME significantly increased the K+ current, while no significant change was detected by the addition of motilin accompanied with D-AA. CONCLUSION The inhibiting effects of motilin on the voltage-dependent K+ current in hippocampal neurons indicate that motilin acts as a regulatory factor for the nitric oxide pathway.
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Affiliation(s)
- Y Lu
- Department of Neonatology, First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shanxi province 710061, China; Department of Physiology, Heze Medical College, Heze, Shandong Province, China.
| | - F Zhong
- Department of Stomatology, Medical College of Qingdao University, Qingdao, Shandong Province 266003, China.
| | - X Wang
- Department of Physiology, Heze Medical College, Heze, Shandong Province, China.
| | - H Li
- Department of Neonatology, First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shanxi province 710061, China.
| | - Z Zhu
- Department of Neonatology, First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shanxi province 710061, China; Shaanxi Province Biomedicine Key Laboratory, College of Life Sciences, Northwest University, Xi'an, Shanxi province, China.
| | - X Kong
- Department of Physiology, Heze Medical College, Heze, Shandong Province, China.
| | - J Zhao
- Department of Physiology, Heze Medical College, Heze, Shandong Province, China.
| | - Q Wu
- Department of Physiology, Heze Medical College, Heze, Shandong Province, China.
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15
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Papamatheakis DG, Chundu M, Blood AB, Wilson SM. Prenatal programming of pulmonary hypertension induced by chronic hypoxia or ductal ligation in sheep. Pulm Circ 2014; 3:757-80. [PMID: 25006393 DOI: 10.1086/674767] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Accepted: 07/28/2013] [Indexed: 11/03/2022] Open
Abstract
Pulmonary hypertension of the newborn is caused by a spectrum of functional and structural abnormalities of the cardiopulmonary circuit. The existence of multiple etiologies and an incomplete understanding of the mechanisms of disease progression have hindered the development of effective therapies. Animal models offer a means of gaining a better understanding of the fundamental basis of the disease. To that effect, a number of experimental animal models are being used to generate pulmonary hypertension in the fetus and newborn. In this review, we compare the mechanisms associated with pulmonary hypertension caused by two such models: in utero ligation of the ductus arteriosus and chronic perinatal hypoxia in sheep fetuses and newborns. In this manner, we make direct comparisons between ductal ligation and chronic hypoxia with respect to the associated mechanisms of disease, since multiple studies have been performed with both models in a single species. We present evidence that the mechanisms associated with pulmonary hypertension are dependent on the type of stress to which the fetus is subjected. Such an analysis allows for a more thorough evaluation of the disease etiology, which can help focus clinical treatments. The final part of the review provides a clinical appraisal of current treatment strategies and lays the foundation for developing individualized therapies that depend on the causative factors.
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Affiliation(s)
- Demosthenes G Papamatheakis
- Division of Pulmonary and Critical Care, University of California San Diego Health System, San Diego, California, USA
| | - Madalitso Chundu
- Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, California, USA
| | - Arlin B Blood
- Department of Pediatrics Division of Neonatology, and Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, California, USA
| | - Sean M Wilson
- Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, California, USA
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16
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Hayoz S, Cubano L, Maldonado H, Bychkov R. Protein kinase A and C regulate leak potassium currents in freshly isolated vascular myocytes from the aorta. PLoS One 2013; 8:e75077. [PMID: 24086441 PMCID: PMC3781042 DOI: 10.1371/journal.pone.0075077] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Accepted: 08/09/2013] [Indexed: 11/18/2022] Open
Abstract
We tested the hypothesis that protein kinase A (PKA) inhibits K2P currents activated by protein kinase C (PKC) in freshly isolated aortic myocytes. PDBu, the PKC agonist, applied extracellularly, increased the amplitude of the K2P currents in the presence of the “cocktail” of K+ channel blockers. Gö 6976 significantly reduced the increase of the K2P currents by PDBu suggesting the involvement of either α or β isoenzymes of PKC. We found that forskolin, or membrane permeable cAMP, did not inhibit K2P currents activated by the PKC. However, when PKA agonists were added prior to PDBu, they produced a strong decrease in the K2P current amplitudes activated by PKC. Inhibition of PDBu-elicited K2P currents by cAMP agonists was not prevented by the treatment of vascular smooth muscle cells with PKA antagonists (H-89 and Rp-cAMPs). Zn2+ and Hg2+ inhibited K2P currents in one population of cells, produced biphasic responses in another population, and increased the amplitude of the PDBu-elicited K+ currents in a third population of myocytes, suggesting expression of several K2P channel types. We found that cAMP agonists inhibited biphasic responses and increase of amplitude of the PDBu-elicited K2P currents produced by Zn2+ and Hg2. 6-Bnz-cAMp produced a significantly altered pH sensitivity of PDBu-elicited K2P-currents, suggesting the inhibition of alkaline-activated K2P-currents. These results indicate that 6-Bnz-cAMP and other cAMP analogs may inhibit K2P currents through a PKA-independent mechanism. cAMP analogs may interact with unidentified proteins involved in K2P channel regulation. This novel cellular mechanism could provide insights into the interplay between PKC and PKA pathways that regulate vascular tone.
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Affiliation(s)
- Sébastien Hayoz
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan, United States of America
- Department of Pharmacology, Universidad Central Del Caribe, Bayamon, Puerto Rico, United States of America
| | - Luis Cubano
- Department of Pharmacology, Universidad Central Del Caribe, Bayamon, Puerto Rico, United States of America
| | - Hector Maldonado
- Department of Pharmacology, Universidad Central Del Caribe, Bayamon, Puerto Rico, United States of America
| | - Rostislav Bychkov
- Department of Pharmacology, Universidad Central Del Caribe, Bayamon, Puerto Rico, United States of America
- * E-mail:
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17
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Levosimendan and its metabolite OR-1896 elicit KATP channel-dependent dilation in resistance arteries in vivo. Pharmacol Rep 2013; 65:1304-10. [DOI: 10.1016/s1734-1140(13)71488-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Revised: 04/11/2013] [Indexed: 11/24/2022]
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18
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Vasodilator compounds derived from plants and their mechanisms of action. Molecules 2013; 18:5814-57. [PMID: 23685938 PMCID: PMC6270466 DOI: 10.3390/molecules18055814] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Revised: 04/24/2013] [Accepted: 05/07/2013] [Indexed: 12/31/2022] Open
Abstract
The present paper reviews vasodilator compounds isolated from plants that were reported in the past 22 years (1990 to 2012) and the different mechanisms of action involved in their vasodilator effects. The search for reports was conducted in a comprehensive manner, intending to encompass those metabolites with a vasodilator effect whose mechanism of action involved both vascular endothelium and arterial smooth muscle. The results obtained from our bibliographic search showed that over half of the isolated compounds have a mechanism of action involving the endothelium. Most of these bioactive metabolites cause vasodilation either by activating the nitric oxide/cGMP pathway or by blocking voltage-dependent calcium channels. Moreover, it was found that many compounds induced vasodilation by more than one mechanism. This review confirms that secondary metabolites, which include a significant group of compounds with extensive chemical diversity, are a valuable source of new pharmaceuticals useful for the treatment and prevention of cardiovascular diseases.
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19
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Kamkaew N, Scholfield CN, Ingkaninan K, Maneesai P, Parkington HC, Tare M, Chootip K. Bacopa monnieri and its constituents is hypotensive in anaesthetized rats and vasodilator in various artery types. JOURNAL OF ETHNOPHARMACOLOGY 2011; 137:790-795. [PMID: 21762768 DOI: 10.1016/j.jep.2011.06.045] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2011] [Revised: 05/03/2011] [Accepted: 06/28/2011] [Indexed: 05/31/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Bacopa monnieri (Brahmi) provides traditional cognitive treatments possibly reflecting improved cerebral hemodynamics. Little is known about the cardiovascular actions of Brahmi. We sought to assess its effects on blood pressure and on isolated arteries, thus providing insights to clinical applications. MATERIALS AND METHODS Intravenous Brahmi (20-60 mg/kg) was tested on arterial blood pressure and heart rate of anaesthetized rats. In vitro vasorelaxation was assessed in arteries, with and without blockers of nitric oxide synthase (L-NAME), cyclooxygenase (indomethacin), and mechanical de-endothelialisation. The effects of Brahmi on Ca(2+) influx and release from stores were investigated. RESULTS Intravenous Brahmi extract (20-60 mg/kg) decreased systolic and diastolic pressures without affecting heart rate. Brahmi evoked relaxation in isolated arteries in order of potency: basilar (IC50=102 ± 16 μg/ml)>mesenteric (171 ± 31)>aortae (213 ± 68)>renal (IC50=375 ± 51)>tail artery (494 ± 93)>femoral arteries (>1,000 μg/ml). Two saponins, bacoside A3 and bacopaside II, had similar vasodilator actions (IC50=8.3 ± 1.7 and 19.5 ± 6.3 μM). In aortae, without endothelium or in L-NAME (10-4M), Brahmi was less potent (IC50=213 ± 68 to 2170 ± 664 and 1192 ± 167 μg/ml, respectively); indomethacin (10-5M) was ineffective. In tail artery, Brahmi inhibited K(+)-depolarization induced Ca(2+) influx and Ca(2+) release from the sarcoplasmic reticulum by phenylephrine (10-5M) or caffeine (20mM). CONCLUSIONS Brahmi reduces blood pressure partly via releasing nitric oxide from the endothelium, with additional actions on vascular smooth muscle Ca(2+) homeostasis. Some Brahmi ingredients could be efficacious antihypertensives and the vasodilation could account for some medicinal actions.
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Affiliation(s)
- Natakorn Kamkaew
- Department of Physiology, Faculty of Medical Science, Naresuan University, Phitsanulok 65000, Thailand
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20
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Takir S, Uydeş-Doğan BS, Ozdemir O. Retina evokes biphasic relaxations in retinal artery unrelated to endothelium, K(V), K(ATP), K(Ca) channels and methyl palmitate. Microvasc Res 2011; 81:295-302. [PMID: 21382382 DOI: 10.1016/j.mvr.2011.02.007] [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: 10/27/2010] [Revised: 02/24/2011] [Accepted: 02/25/2011] [Indexed: 11/17/2022]
Abstract
Retinal relaxing factor (RRF) is suggested to be released from the retina and to contribute in the maintenance of retinal arterial tone. Herein, we aimed to clarify the effects of retinal tissue in isolated bovine retinal arteries in comparison with choroidal tissue and to evaluate the possible role of endothelium and potassium channels. In parallel, the effects of palmitic acid methyl ester (PAME), a putative vasodilator proposed to be released from the retina, was also examined. A piece of bovine retinal or choroidal tissue was placed within a close proximity on top of retinal arteries mounted in a wire myograph and precontracted with noradrenaline, prostaglandin F(2α), endothelin-1, thromboxane A(2) mimetic, U46619 or potassium (K(+)). To elucidate possible mechanisms in the effects of retinal tissue, retinal arteries were either deendothelized or incubated with inhibitors of endothelial vasodilators, i.e. nitric oxide (NO) and prostaglandins, or K(+) channels. Unlike the choroid, retinal tissue produced rapid, biphasic and complete relaxations in isolated bovine retinal arteries precontracted with various spasmogens acting on distinct receptors. Endothelium removal or preincubation of retinal arteries with inhibitors of NO synthase; L-NOARG (10(-4)M), guanylate cyclase; ODQ (10(-5)M) and cyclooxygenase; indomethacin (10(-5)M), did not cause a significant difference in the relaxation profile. Additionally, retinal relaxations remained unchanged in the presence of respective inhibitors of ATP-sensitive (K(ATP)) (glibenclamide, 10(-5)M), voltage-dependent (K(V)) (4-aminopyridine, 2×10(-3)M), and calcium-activated (K(Ca)) (tetraethylammonium 10mM; charybdotoxin, 10(-7)M; and apamin, 5×10(-7)M) K(+) channels. Thus, our results provide novel evidence regarding the biphasic relaxing profile of RRF in the retinal artery which was unrelated to endothelium and K(+) channels (K(ATP), K(V) and K(Ca)). Interestingly, PAME (10(-14)-10(-5)M) did not provoke a relaxation in bovine retinal artery suggesting no association with RRF.
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Affiliation(s)
- Selçuk Takir
- Department of Pharmacology, Faculty of Pharmacy, Istanbul University, Istanbul, Turkey
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21
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Cidad P, Moreno-Domínguez A, Novensá L, Roqué M, Barquín L, Heras M, Pérez-García MT, López-López JR. Characterization of ion channels involved in the proliferative response of femoral artery smooth muscle cells. Arterioscler Thromb Vasc Biol 2010; 30:1203-11. [PMID: 20299686 DOI: 10.1161/atvbaha.110.205187] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Vascular smooth muscle cells (VSMCs) contribute significantly to occlusive vascular diseases by virtue of their ability to switch to a noncontractile, migratory, and proliferating phenotype. Although the participation of ion channels in this phenotypic modulation (PM) has been described previously, changes in their expression are poorly defined because of their large molecular diversity. We obtained a global portrait of ion channel expression in contractile versus proliferating mouse femoral artery VSMCs, and explored the functional contribution to the PM of the most relevant changes that we observed. METHODS AND RESULTS High-throughput real-time polymerase chain reaction of 87 ion channel genes was performed in 2 experimental paradigms: an in vivo model of endoluminal lesion and an in vitro model of cultured VSMCs obtained from explants. mRNA expression changes showed a good correlation between the 2 proliferative models, with only 2 genes, Kv1.3 and Kvbeta2, increasing their expression on proliferation. The functional characterization demonstrates that Kv1.3 currents increased in proliferating VSMC and that their selective blockade inhibits migration and proliferation. CONCLUSIONS These findings establish the involvement of Kv1.3 channels in the PM of VSMCs, providing a new therapeutical target for the treatment of intimal hyperplasia.
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MESH Headings
- Animals
- Cell Movement
- Cell Proliferation/drug effects
- Cells, Cultured
- Cluster Analysis
- Disease Models, Animal
- Femoral Artery/metabolism
- Femoral Artery/pathology
- Gene Expression Profiling
- Genotype
- Hyperplasia
- Kv1.3 Potassium Channel/antagonists & inhibitors
- Kv1.3 Potassium Channel/genetics
- Kv1.3 Potassium Channel/metabolism
- Membrane Potentials
- Mice
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/injuries
- Muscle, Smooth, Vascular/metabolism
- Muscle, Smooth, Vascular/pathology
- Myocytes, Smooth Muscle/drug effects
- Myocytes, Smooth Muscle/metabolism
- Myocytes, Smooth Muscle/pathology
- Phenotype
- Potassium Channel Blockers/pharmacology
- RNA, Messenger/metabolism
- Shaker Superfamily of Potassium Channels/genetics
- Shaker Superfamily of Potassium Channels/metabolism
- Up-Regulation
- Vasoconstriction
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Affiliation(s)
- Pilar Cidad
- Departamento de Bioquímica y Biología Molecular y Fisiología e Instituto de Biología y Genética Molecular, Universidad de Valladolid y Consejo superior de Investigaciones Cientificas, Valladolid, Spain
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22
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Lunardi CN, da Silva RS, Bendhack LM. New nitric oxide donors based on ruthenium complexes. Braz J Med Biol Res 2009; 42:87-93. [PMID: 19219301 DOI: 10.1590/s0100-879x2009000100013] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2008] [Accepted: 01/12/2008] [Indexed: 11/21/2022] Open
Abstract
Nitric oxide (NO) donors produce NO-related activity when applied to biological systems. Among its diverse functions, NO has been implicated in vascular smooth muscle relaxation. Despite the great importance of NO in biological systems, its pharmacological and physiological studies have been limited due to its high reactivity and short half-life. In this review we will focus on our recent investigations of nitrosyl ruthenium complexes as NO-delivery agents and their effects on vascular smooth muscle cell relaxation. The high affinity of ruthenium for NO is a marked feature of its chemistry. The main signaling pathway responsible for the vascular relaxation induced by NO involves the activation of soluble guanylyl-cyclase, with subsequent accumulation of cGMP and activation of cGMP-dependent protein kinase. This in turn can activate several proteins such as K+ channels as well as induce vasodilatation by a decrease in cytosolic Ca2+. Oxidative stress and associated oxidative damage are mediators of vascular damage in several cardiovascular diseases, including hypertension. The increased production of the superoxide anion (O2-) by the vascular wall has been observed in different animal models of hypertension. Vascular relaxation to the endogenous NO-related response or to NO released from NO deliverers is impaired in vessels from renal hypertensive (2K-1C) rats. A growing amount of evidence supports the possibility that increased NO inactivation by excess O2- may account for the decreased NO bioavailability and vascular dysfunction in hypertension.
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Affiliation(s)
- C N Lunardi
- Laboratório de Farmacologia, Departamento de Física e Química, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil.
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23
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Calderone V, Martelli A, Testai L, Martinotti E, Breschi MC. Functional contribution of the endothelial component to the vasorelaxing effect of resveratrol and NS 1619, activators of the large-conductance calcium-activated potassium channels. Naunyn Schmiedebergs Arch Pharmacol 2007; 375:73-80. [PMID: 17203288 DOI: 10.1007/s00210-006-0129-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2006] [Accepted: 11/29/2006] [Indexed: 11/26/2022]
Abstract
Large-conductance calcium-activated potassium channels (BK) of smooth muscle play a role in the relevant modulation of vascular tone, due to their calcium- and voltage-dependent mechanisms of activation. A potential role of endothelial BK channels has also been suggested by approaches on endothelial cell cultures. However, no functional study, aimed at evaluating the contribution of endothelial BK channels to the effect of BK-openers, has been reported. Resveratrol and NS 1619, BK-openers, have been tested on endothelium-intact and -denuded aortic rings. Furthermore, the effects of high depolarisation of potassium channel blockers TEA (Tetraethylammonium), 4-AP ( 4-Aminopyridine) and IbTX (Iberiotoxin) and of inhibitors of NO-pathway (L-NAME and ODQ) have been evaluated. The presence of endothelium increased the vasorelaxing potency of BK-openers. This potentiation was eliminated by L-NAME and ODQ. TEA, 4-AP, IbTX and high depolarisation had modest or no antagonist influence on resveratrol in endothelium-denuded aortic rings. The effects of NS 1619 on endothelium-denuded aortic rings were not affected by IbTX, and were modestly antagonised by TEA, 4-AP and high depolarisation. In intact endothelium vessels, TEA, IbTX and 4-AP antagonised the vasorelaxing effect of the two BK-activators. A BK-mediated release of endothelial NO seems a very important factor, determining a strong influence on vasodilator profile of BK-openers. Therefore, an eventual therapy with a BK-opener could promote a series of cardiovascular impacts not confined to the only direct vasorelaxing effects, but also due to a significant contribution of endothelial NO.
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Affiliation(s)
- Vincenzo Calderone
- Dipartimento di Psichiatria, Neurobiologia, Farmacologia e Biotecnologie, Università di Pisa, Via Bonanno 6, 56126, Pisa, Italy.
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24
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Erdei N, Papp Z, Pollesello P, Édes I, Bagi Z. The levosimendan metabolite OR-1896 elicits vasodilation by activating the K(ATP) and BK(Ca) channels in rat isolated arterioles. Br J Pharmacol 2006; 148:696-702. [PMID: 16715115 PMCID: PMC1751872 DOI: 10.1038/sj.bjp.0706781] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1. We characterized the vasoactive effects of OR-1896, the long-lived metabolite of the inodilator levosimendan, in coronary and skeletal muscle microvessels. 2. The effect of OR-1896 on isolated, pressurized (80 mmHg) rat coronary and gracilis muscle arteriole (approximately 150 microm) diameters was investigated by videomicroscopy. 3. OR-1896 elicited concentration-dependent (1 nM-10 microM) dilations in coronary (maximal dilation: 66+/-6%, relative to that in Ca2+-free solutions; pD2: 7.16+/-0.42) and gracilis muscle arterioles (maximal dilation: 73+/-4%; pD2: 6.71+/-0.42), these dilations proving comparable to those induced by levosimendan (1 nM-10 microM) in coronary (maximal dilation: 83+/-6%; pD2: 7.06+/-0.14) and gracilis muscle arterioles (maximal dilation: 73+/-12%; pD2: 7.05+/-0.1). 4. The maximal dilations in response to OR-1896 were significantly (P<0.05) attenuated by the nonselective K+ channel inhibitor tetraethylammonium (1 mM) in coronary (to 34+/-9%) and gracilis muscle arterioles (to 28+/-6%). 5. Glibenclamide (5 or 10 microM), a selective ATP-sensitive K+ channel (KATP) blocker, elicited a greater reduction of OR-1896-induced dilations in skeletal muscle arterioles than in coronary microvessels. 6. Conversely, the selective inhibition of the large conductance Ca2+-activated K+ channels (BK(Ca)) with iberiotoxin (100 nM) significantly reduced the OR-1896-induced maximal dilation in coronary arterioles (to 21+/-6%), but was ineffective in skeletal muscle arterioles (72+/-8%). 7. Accordingly, OR-1896 elicits a substantial vasodilation in coronary and skeletal muscle arterioles, by activating primarily BK(Ca) and K(ATP) channels, respectively, and it is suggested that OR-1896 contributes to the long-term hemodynamic effects of levosimendan.
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Affiliation(s)
- Nóra Erdei
- Division of Clinical Physiology, Institute of Cardiology, University of Debrecen, Debrecen H-4004, Hungary
| | - Zoltán Papp
- Division of Clinical Physiology, Institute of Cardiology, University of Debrecen, Debrecen H-4004, Hungary
| | | | - István Édes
- Division of Clinical Physiology, Institute of Cardiology, University of Debrecen, Debrecen H-4004, Hungary
| | - Zsolt Bagi
- Division of Clinical Physiology, Institute of Cardiology, University of Debrecen, Debrecen H-4004, Hungary
- Author for correspondence:
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25
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Miguel-Velado E, Moreno-Domínguez A, Colinas O, Cidad P, Heras M, Pérez-García MT, López-López JR. Contribution of Kv channels to phenotypic remodeling of human uterine artery smooth muscle cells. Circ Res 2005; 97:1280-7. [PMID: 16269658 DOI: 10.1161/01.res.0000194322.91255.13] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Vascular smooth muscle cells (VSMCs) perform diverse functions that can be classified into contractile and synthetic (or proliferating). All of these functions can be fulfilled by the same cell because of its capacity of phenotypic modulation in response to environmental changes. The resting membrane potential is a key determinant for both contractile and proliferating functions. Here, we have explored the expression of voltage-dependent K+ (Kv) channels in contractile (freshly dissociated) and proliferating (cultured) VSMCs obtained from human uterine arteries to establish their contribution to the functional properties of the cells and their possible participation in the phenotypic switch. We have studied the expression pattern (both at the mRNA and at the protein level) of Kvalpha subunits in both preparations as well as their functional contribution to the K+ currents of VSMCs. Our results indicate that phenotypic remodeling associates with a change in the expression and distribution of Kv channels. Whereas Kv currents in contractile VSMCs are mainly performed by Kv1 channels, Kv3.4 is the principal contributor to K+ currents in cultured VSMCs. Furthermore, selective blockade of Kv3.4 channels resulted in a reduced proliferation rate, suggesting a link between Kv channels expression and phenotypic remodeling.
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Affiliation(s)
- Eduardo Miguel-Velado
- Departamento de Bioquímica y Biología Molecular y Fisiología, Instituto de Biología y Genética, Universidad de Valladolid, Facultad de Medicina, Consejo Superior de Investigaciones Científicas, Valladolid, Spain
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26
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Yang SK, Parkington HC, Blake AD, Keating DJ, Chen C. Somatostatin increases voltage-gated K+ currents in GH3 cells through activation of multiple somatostatin receptors. Endocrinology 2005; 146:4975-84. [PMID: 16081634 DOI: 10.1210/en.2005-0696] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The secretion of GH by somatotropes is inhibited by somatostatin (SRIF) through five specific membrane receptors (SSTRs). SRIF increases both transient outward (IA) and delayed rectifying (IK) K+ currents. We aim to clarify the subtype(s) of SSTRs involved in K+ current enhancement in GH3 somatotrope cells using specific SSTR subtype agonists. Expression of all five SSTRs was confirmed in GH3 cells by RT-PCR. Nystatin-perforated patch clamp was used to record voltage-gated K+ currents. We first established the presence of IA and IK type K+ currents in GH3 cells using different holding potentials (-40 or -70 mV) and specific blockers (4-aminopirimidine and tetraethylammonium chloride). SRIF (200 nM) increased the amplitude of both IA and IK in a fully reversible manner. Various concentrations of each specific SRTR agonist were tested on K+ currents to find the maximal effective concentration. Activation of SSTR2 and SSTR4 by their respective agonists, L-779,976 and L-803,087 (10 nM), increased K+ current amplitude without preference to IA or IK, and abolished any further increase by SRIF. Activation of SSTR1 and SSTR5 by their respective agonists, L-797,591 or L-817,818 (10 nM), increased K+ current amplitude, but SRIF evoked a further increase. The SSTR3 agonist L-797,778 (10 nM) did not affect the K+ currents or the response to SRIF. These results indicate that SSTR1, -2, -4, and -5 may all be involved in the enhancement of K+ currents by SRIF but that only the activation of SSTR2 or -4 results in the full activation of K+ current caused by SRIF.
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Affiliation(s)
- Seung-Kwon Yang
- Prince Henry's Institute of Medical Research, Monash University, Melbourne, Australia
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Salapatek AMF, Ji J, Muinuddin A, Diamant NE. Potassium channel diversity within the muscular components of the feline lower esophageal sphincter. Can J Physiol Pharmacol 2005; 82:1006-17. [PMID: 15644941 DOI: 10.1139/y04-090] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We hypothesized that regional differences in electrophysiological properties exist within the musculature of the feline lower esophageal sphincter (LES) and that they may potentially contribute to functional asymmetry within the LES. Freshly isolated esophageal smooth muscle cells (SMCs) from the circular muscle and sling regions within the LES were studied under a patch clamp. The resting membrane potential (RMP) of the circular SMCs was significantly more depolarized than was the RMP of the sling SMCs, resulting from a higher Na+ and Cl- permeability in circular muscle than in sling muscle. Large conductance Ca2+-activated K+ (BKCa) set the RMP at both levels, since specific BKCa inhibitors caused depolarization; however, BKCa density was greatest in the circular region. A significant portion of the outward current was due to non-BKCa, especially in sling muscle, and likely delayed rectifier K+ channels (KDR). There was a large reduction in outward current with 4-aminopyridine (4-AP) in sling muscle, while BKCa blockers had a limited effect on the voltage-activated outward current in sling muscle. Differences in BKCa:KDR channel ratios were also manifest by a leftward shift in the voltage-dependent activation curve in circular cells compared to sling cells. The electrophysiological differences seen between the circular and sling muscles provide a basis for their different contributions to LES activities such as resting tone and neurotransmitter responsiveness, and in turn could impart asymmetric drug responses and provide specific therapeutic targets.
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Affiliation(s)
- Anne Marie F Salapatek
- Toronto Western Research Institute, University Health Network, University of Toronto, ON, Canada
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28
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Mauban JRH, Remillard CV, Yuan JXJ. Hypoxic pulmonary vasoconstriction: role of ion channels. J Appl Physiol (1985) 2005; 98:415-20. [PMID: 15591311 DOI: 10.1152/japplphysiol.00732.2004] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Acute hypoxia induces pulmonary vasoconstriction and chronic hypoxia causes structural changes of the pulmonary vasculature including arterial medial hypertrophy. Electro- and pharmacomechanical mechanisms are involved in regulating pulmonary vasomotor tone, whereas intracellular Ca(2+) serves as an important signal in regulating contraction and proliferation of pulmonary artery smooth muscle cells. Herein, we provide a basic overview of the cellular mechanisms involved in the development of hypoxic pulmonary vasoconstriction. Our discussion focuses on the roles of ion channels permeable to K(+) and Ca(2+), membrane potential, and cytoplasmic Ca(2+) in the development of acute hypoxic pulmonary vasoconstriction and chronic hypoxia-mediated pulmonary vascular remodeling.
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Affiliation(s)
- Joseph R H Mauban
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of California-San Diego, 9500 Gilman Dr., MC 0725, La Jolla, CA 92093-0725, USA
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29
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Gao Y, Raj JU. Parathyroid hormone-related protein-mediated responses in pulmonary arteries and veins of newborn lambs. Am J Physiol Lung Cell Mol Physiol 2005; 289:L60-6. [PMID: 15749740 DOI: 10.1152/ajplung.00411.2004] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
PTHrP has important roles in lung development and function. Here we determined the vasomotor responses of isolated pulmonary arteries and veins of newborn and adult sheep to PTHrP. In vessels constricted with endothelin-1, PTHrP (PTHrP 1-34) caused greater relaxation of veins than of arteries. In both vessel types, relaxation to the peptide was less in adult than in newborn vessels. In newborn lambs, PTHrP-induced relaxation was not affected by endothelium removal, inhibition of eNOS, or inhibition of adenylyl cyclases by SQ-22536. However, relaxation was attenuated by 4-aminopyridine, inhibitor of voltage-dependent potassium channels, in both arteries and veins, and by charybdotoxin, inhibitor of calcium-activated potassium channels, in veins. When vessels were saturated with 8-BrcAMP (3 x 10(-4) M), to eliminate relaxation mediated by endogenous cAMP, PTHrP-induced relaxation was partially attenuated. In vessels treated with 8-BrcAMP (3 x 10(-4) M), 4-aminopyridine but not charybdotoxin inhibited relaxation induced by PTHrP 1-34 in both arteries and veins. Radioimmunoassay showed that, in the presence of a general phosphodiesterase inhibitor, PTHrP caused a concentration-dependent increase in intracellular cAMP content in arteries and veins, which was largely abolished by SQ-22536. Our results demonstrate that PTHrP is a potent vasodilator of pulmonary vessels, with a greater effect in veins than in arteries. Relaxation induced by the peptide contains both cAMP-dependent and -independent components. In both arteries and veins, voltage-dependent potassium channels mediate the response to PTHrP, at least in part, in a cAMP-independent fashion; and in veins, calcium-activated potassium channels may be stimulated by elevated cAMP levels.
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Affiliation(s)
- Yuansheng Gao
- Division of Neonatology, Los Angeles Biomedical Research Institute, Harbor-UCLA Medical Center, Torrance, CA 90502, USA.
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30
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Suzuki T, Takimoto K. Differential expression of Kv4 pore-forming and KChIP auxiliary subunits in rat uterus during pregnancy. Am J Physiol Endocrinol Metab 2005; 288:E335-41. [PMID: 15454398 DOI: 10.1152/ajpendo.00250.2004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Regulation of voltage-gated K(+) (K(v)) channel expression may be involved in controlling contractility of uterine smooth muscle cells during pregnancy. Functional expression of these channels is not only controlled by the levels of pore-forming subunits, but requires their association with auxiliary subunits. Specifically, rapidly inactivating K(v) current is prominent in myometrial cells and may be carried by complexes consisting of Kv4 pore-forming and KChIP auxiliary subunits. To determine the molecular identity of the channel complexes and their changes during pregnancy, we examined the expression and localization of these subunits in rat uterus. RT-PCR analysis revealed that rat uterus expressed all three Kv4 pore-forming subunits and KChIP2 and -4 auxiliary subunits. The expression of mRNAs for these subunits was dynamically and region selectively regulated during pregnancy. In the corpus, Kv4.2 mRNA level increased before parturition, whereas the expression of Kv4.1 and Kv4.3 mRNAs decreased during pregnancy. A marked increase in KChIP2 mRNA level was also seen at late gestation. In the cervix, the expression of all three pore-forming and two auxiliary subunit mRNAs increased at late gestation. Immunoprecipitation followed by immunoblot analysis indicated that Kv4.2-KChIP2 complexes were significant in uterus at late pregnancy. Kv4.2- and KChIP2-immunoreactive proteins were present in both circular and longitudinal myometrial cells. Finally, Kv4.2 and KChIP2 mRNA levels were similarly elevated in pregnant and nonpregnant corpora of one side-conceived rats. These results suggest that diffusible factors coordinate the pregnancy-associated changes in molecular compositions of myometrial Kv4-KChIP channel complexes.
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Affiliation(s)
- Takahiro Suzuki
- Dept. of Environmental and Occupational Health, University of Pittsburgh, 3343 Forbes Avenue, Pittsburgh, PA 15260, USA
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31
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Xie W, Wang H, Wang H, Hu G. Effects of iptakalim hydrochloride, a novel KATP channel opener, on pulmonary vascular remodeling in hypoxic rats. Life Sci 2004; 75:2065-76. [PMID: 15312751 DOI: 10.1016/j.lfs.2004.03.031] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2003] [Accepted: 03/29/2004] [Indexed: 11/19/2022]
Abstract
To investigate whether pulmonary artery remodeling could be prevented or not in hypoxic pulmonary hypertensive rats by treatment, the effects of iptakalim hydrochloride, a novel KATPCO, were evaluated. Iptakalim hydrochloride was orally administered at the doses of either 1.5 mg/kg/day or 0.75 mg/kg/day before their 4-week exposure to hypoxia (10% oxygen). It was demonstrated that iptakalim hydrochloride could reverse all pathological indices of pulmonary arterial remodeling and significantly reduce right ventricular hypertrophy in hypoxic rats. The reversal of hypoxic indices was dose-dependent, in which the higher dose of iptakalim hydrochloride reversed pathological indices more effectively than the lower dose did. This was further confirmed electrophysiologically using whole cell patch-clamp technique, which revealed that the outward potassium currents could be enhanced by iptakalim hydrochloride, and the decrease of K+ current density and increase of membrane capacitance could be reversed by chronic iptakalim hydrochloride treatment. These findings implied that iptakalim hydrochloride could play its role through activating plasmalemmal K+ channels of pulmonary arterial SMCs. The results indicated that iptakalim hydrochloride had anti-remodeling properties of pulmonary artery in hypoxic pulmonary hypertensive rats. It is therefore suggested that KATPCOs might be promising in the treatment of patients with hypoxic, and even possibly other forms of, pulmonary hypertension.
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Affiliation(s)
- Weiping Xie
- Department of Pharmacology and Neurobiology, Nanjing Medical University,140 Hanzhong Road, 210029, China
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32
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Tsang SY, Yao X, Wong CM, Chan FL, Chen ZY, Huang Y. Differential regulation of K+ and Ca2+ channel gene expression by chronic treatment with estrogen and tamoxifen in rat aorta. Eur J Pharmacol 2004; 483:155-62. [PMID: 14729103 DOI: 10.1016/j.ejphar.2003.10.031] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The beneficial effect of estrogen on the vascular system is partly associated with its ability to reduce vascular contractility. Estrogen acutely activates large-conductance Ca(2+)-activated K(+) channel (BK(Ca)) and inhibits L-type voltage-gated Ca(2+) channel (VGCC) in vascular smooth muscle cells. However, a long-term influence of estrogen, estrogen deficiency, or selective estrogen receptor modulators on gene expression of these ion channels is unclear. This study was therefore aimed to determine the relative mRNA expression levels of alpha- and beta-subunits of BK(Ca), K(V)1.5 subtype of delayed rectifier K(+) channel (K(V)), and alpha(1C) subunit of L-type VGCC in endothelium-denuded aortas from female rats by a semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) analysis. Rats were divided into four experimental groups: (i) sham-operated control, (ii) ovariectomized, (iii) ovariectomized with 17 beta-estradiol treatment and (iv) ovariectomized with tamoxifen treatment. The results showed that ovariectomy decreased the mRNA expression of K(V)1.5 while it increased the mRNA expression of alpha(1C) subunit of L-type VGCC. Ovariectomy-induced modulation of gene expression of these ion channels was completely prevented in ovariectomized rats receiving chronic treatment with estrogen or tamoxifen. In contrast, the expression levels of genes encoding both alpha- and beta-subunits of BK(Ca) remained the same in the four animal groups. The present study has provided the first line of evidence suggesting the long-term beneficial effects of estrogen and tamoxifen therapy on vascular ion channel expressions, which may be an important mechanism by which the favorable modulation of vessel tone by estrogen or selective estrogen receptor modulators is mediated.
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Affiliation(s)
- Suk Ying Tsang
- Department of Physiology, Faculty of Medicine, Chinese University of Hong Kong, Shatin, NT, Hong Kong, China
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Gurney AM, Osipenko ON, MacMillan D, McFarlane KM, Tate RJ, Kempsill FEJ. Two-pore domain K channel, TASK-1, in pulmonary artery smooth muscle cells. Circ Res 2003; 93:957-64. [PMID: 14551239 DOI: 10.1161/01.res.0000099883.68414.61] [Citation(s) in RCA: 137] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Pulmonary vascular tone is strongly influenced by the resting membrane potential of smooth muscle cells, depolarization promoting Ca2+ influx, and contraction. The resting potential is determined largely by the activity of K+-selective ion channels, the molecular nature of which has been debated for some time. In this study, we provide strong evidence that the two-pore domain K+ channel, TASK-1, mediates a noninactivating, background K+ current (IKN), which sets the resting membrane potential in rabbit pulmonary artery smooth muscle cells (PASMCs). TASK-1 mRNA was found to be present in PASMCs, and the membranes of PASMCs contained TASK-1 protein. Both IKN and the resting potential were found to be exquisitely sensitive to extracellular pH, acidosis inhibiting the current and causing depolarization. Moreover, IKN and the resting potential were enhanced by halothane (1 mmol/L), inhibited by Zn2+ (100 to 200 micromol/L) and anandamide (10 micromol/L), but insensitive to cytoplasmic Ca2+. These properties are all diagnostic of TASK-1 channels and add to previously identified features of IKN that are shared with TASK-1, such as inhibition by hypoxia, low sensitivity to 4-aminopyridine and quinine and insensitivity to tetraethylammonium ions. It is therefore concluded that TASK-1 channels are major contributors to the resting potential in pulmonary artery smooth muscle. They are likely to play an important role in mediating pulmonary vascular responses to changes in extracellular pH, and they could be responsible for the modulatory effects of pH on hypoxic pulmonary vasoconstriction.
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Affiliation(s)
- A M Gurney
- Department of Physiology and Pharmacology, University of Strathclyde, 27 Taylor St, Glasgow, UK G4 0NR.
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Liu R, Ishibe Y, Okazaki N, Ueda M, Hirosawa J. Volatile anesthetics regulate pulmonary vascular tension through different potassium channel subtypes in isolated rabbit lungs. Can J Anaesth 2003; 50:301-4. [PMID: 12620956 DOI: 10.1007/bf03017802] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
BACKGROUND The effects of volatile anesthetics on subtypes of K(+) channels located on pulmonary vessels remain largely unexplored. METHODS To investigate whether or not potassium channels play a role in the effect of volatile anesthetic on pulmonary vessels, isolated and perfused rabbit lungs were divided into four groups (n = 7 each): a control group without treatment, a glibenclamide (Glib) group treated with adenosine triphosphate-sensitive K(+) (K(ATP)) channel inhibitor, a 4-aminopyridine (4-AP) group treated with voltage-sensitive K(+) (K(V)) channel inhibitor, and an iberiotoxin (IbTX) group treated with high conductance calcium-activated K(+) (K(Ca)) channel inhibitor. After inhibitor administration and stabilization, two minimum alveolar concentration (MAC) of halothane, enflurane, isoflurane, or 1.8 MAC of sevoflurane were randomly administered for 15 min followed by eight minutes of fresh gas mixture after each agent inhalation. RESULTS Isoflurane did not change pulmonary vascular tension in the control group but instead constricted the pulmonary vessels when K(V) channels were inhibited with 4-AP; constrictive effects of enflurane and halothane were observed on pulmonary vessels, and were enhanced by K(V) channel inhibition with 4-AP, but they were inhibited by K(Ca) channel inhibition with IbTX; the dilation effect of sevoflurane was observed on pulmonary vessels but was not significantly affected by any of the K(+) channel inhibitors. CONCLUSION Halothane, enflurane and isoflurane, but not sevoflurane, regulate pulmonary vascular tension through K(V) and/or K(Ca) channels in isolated rabbit lungs.
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Affiliation(s)
- Renyu Liu
- Department of Anaesthesiology and Reanimatology, Tottori University Faculty of Medicine, Yonago, Japan.
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Fergus DJ, Martens JR, England SK. Kv channel subunits that contribute to voltage-gated K+ current in renal vascular smooth muscle. Pflugers Arch 2003; 445:697-704. [PMID: 12632190 DOI: 10.1007/s00424-002-0994-7] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2002] [Accepted: 11/07/2002] [Indexed: 11/29/2022]
Abstract
The rat renal arterial vasculature displays differences in K(+) channel current phenotypes along its length. Small arcuate to cortical radial arteries express a delayed rectifier phenotype, while the predominant Kv current in larger arcuate and interlobar arteries is composed of both transient and sustained components. We sought to determine whether Kvalpha subunits in the rat renal interlobar and arcuate arteries form heterotetramers, which may account for the unique currents, and whether modulatory Kvbeta subunits are present in renal vascular smooth muscle cells. RT-PCR indicated the presence of several different Kvalpha subunit isoform transcripts. Co-immunoprecipitation with immunoblotting and immunohistochemical evidence suggests that a portion of the K(+) current phenotype is a heteromultimer containing delayed-rectifier Kv1.2 and A-type Kv1.4 channel subunits. RT-PCR and immunoblot analyses also demonstrated the presence of both Kvbeta1.2 and Kvbeta1.3 in renal arteries. These results suggest that heteromultimeric formation of Kvalpha subunits and the presence of modulatory Kvbeta subunits are important factors in mediating Kv currents in the renal microvasculature and suggest a potentially critical role for these channel subunits in blood pressure regulation.
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Affiliation(s)
- Daniel J Fergus
- Department of Physiology and Biophysics, 5-660 Bowen Science Building, University of Iowa, Iowa City, Iowa 52242, USA
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Abstract
Four normal and 79 human prostate cancer (Pca) specimens were examined, by immunohistochemistry, for expression of voltage-gated potassium ion channels. Strong immunostaining (for Kv1.3) was observed in the normal and 47% (37/79) of Pca specimens. Twenty-nine percent (23/79) Pca specimens showed moderate and 24% (19/79) displayed low staining. Three potassium channel-openers at a concentration of 10 microg/mL, minoxidil (47.8 microM), 1-Ethyl-2-benzimidazolinone (EBIO) (61.7 microM) and diazoxide (43.3 microM), increased growth of PC3 cells by 30-50%. Potassium channel-blockers, dequalinium, amiodarone and glibenclamide, caused a dose-dependent, growth inhibition of four human Pca cell lines. Apoptosis occurred within 4h of treatment of PC3 cells with dequalinium (0.5 microg/mL, 0.9 microM), amiodarone (5 microg/mL, 7.3 microM) or glibenclamide (50 microg/mL, 0.1mM).
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Affiliation(s)
- Mansoor Abdul
- Rumbaugh-Goodwin Institute for Cancer Research, 1850 NW 69 Ave #5, Plantation, FL 33313, USA
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37
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Waypa GB, Schumacker PT. O(2) sensing in hypoxic pulmonary vasoconstriction: the mitochondrial door re-opens. Respir Physiol Neurobiol 2002; 132:81-91. [PMID: 12126697 DOI: 10.1016/s1569-9048(02)00051-4] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The identity of the O(2) sensor underlying the hypoxic pulmonary vasoconstriction (HPV) response has been sought for more than 50 years. Recently, the mitochondria have again come into sharp focus as the cellular organelle responsible for triggering the events that culminate in pulmonary artery constriction. Studies from different laboratories propose two disparate models to explain how mitochondria react to a decrease in P(O(2)). One model proposes that hypoxia slows or inhibits mitochondrial electron transport resulting in the accumulation of reducing equivalents and a decrease in the generation of reactive oxygen species (ROS). This is proposed to activate a redox-sensitive pathway leading to pulmonary vasoconstriction. A second and opposing model suggests that hypoxia triggers a paradoxical increase in mitochondrial ROS generation. This increase would then lead to the activation of an oxidant-sensitive signaling transduction pathway leading to HPV. This article summarizes the potential involvement of mitochondria in these two very different models.
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Affiliation(s)
- Gregory B Waypa
- Department of Medicine MC6026, The University of Chicago, 5841 South Maryland Avenue, Chicago, IL 60637, USA
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38
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Salapatek AMF, Ji J, Diamant NE. Ion channel diversity in the feline smooth muscle esophagus. Am J Physiol Gastrointest Liver Physiol 2002; 282:G288-99. [PMID: 11804850 DOI: 10.1152/ajpgi.00124.2001] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
We have characterized ion-channel identity and density differences along the feline smooth muscle esophagus using patch-clamp recording. Current clamp recording revealed that the resting membrane potential (RMP) of esophageal smooth muscle cells (SMC) from the circular layer at 4 cm above the lower esophageal sphincter (EBC4; LES) were more depolarized than at 2 cm above LES. Higher distal Na(+) permeability (but not Cl(-) permeability) contributes to this RMP difference. K(+) channels but not large-conductance Ca(2+)-activated K(+) (BK(Ca)) channels contribute to RMP at both levels, because nonspecific K(+)-channel blockers depolarize all SMC. Depolarization of SMC under voltage clamp revealed that the density of voltage-dependent K(+) channels (K(V)) was greatest at EBC4 due to increased BK(Ca.) Delayed rectifier K(+) channels (K(DR)), compatible with subtype K(V)1.2, were present at both levels. Differences in K(Ca)-to-K(DR) channel ratios were also manifest by predictable shifts in voltage-dependent inactivation at EBC4 when BK(Ca) channels were blocked. We provide the first evidence for regional electrophysiological differences along the esophageal body resulting from SMC ion channel diversity, which could allow for differential muscular responses to innervation and varied muscular contribution to peristaltic contractions along the esophagus.
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39
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Abstract
Potassium channel dysfunction plays a role in the pathogenesis of a number of vascular diseases including pulmonary and systemic hypertension, diabetes, and complications of atherosclerosis. Two types of K+ channels that are known to be prevalent and contribute significantly to the repolarization of vascular smooth muscle cell (SMC) membranes are the high-conductance Ca(2+)- and voltage-activated K+ (BKCa) channels, and the voltage-gated K+ (KV) channels. Alterations in either BKCa or KV channel function can have dramatic effects on vascular tone. To date, hereditary and congenital mutations in genes encoding K+ channels, abnormalities in transcription, posttranslational modifications, and altered responses to intracellular second messengers have been described as potential mechanisms for several cardiovascular diseases. Comprehensive approaches including genetic, biochemical, molecular biological, and electrophysiological analyses are necessary to identify the levels at which K+ channel expression patterns or function are disrupted. Additionally, reproducing clinical pathologies in animal, organ, and virtual models has been important in studying the discrete mechanisms by which the structure and function of these channels are altered in pathophysiological conditions. This article will describe approaches that are currently used to identify abnormalities in BKCa and KV channels that may exist in diseases involving vascular dysfunction.
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MESH Headings
- Animals
- Cardiovascular Diseases/physiopathology
- Gene Expression Regulation
- Humans
- Large-Conductance Calcium-Activated Potassium Channels
- Membrane Potentials/drug effects
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/physiology
- Myocytes, Smooth Muscle/drug effects
- Myocytes, Smooth Muscle/physiology
- Patch-Clamp Techniques
- Potassium Channel Blockers/pharmacology
- Potassium Channels, Calcium-Activated/antagonists & inhibitors
- Potassium Channels, Calcium-Activated/genetics
- Potassium Channels, Calcium-Activated/physiology
- Potassium Channels, Voltage-Gated/antagonists & inhibitors
- Potassium Channels, Voltage-Gated/genetics
- Potassium Channels, Voltage-Gated/physiology
- Vasodilation/drug effects
- Vasodilation/physiology
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Affiliation(s)
- Victoria P Korovkina
- Department of Physiology and Biophysics, 6-432 Bowen Science Building, University of Iowa, Iowa City, IA 52242, USA
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40
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Abstract
Altered function of K+ channels associated with hypertension has been inferred from the effects of K+ channel blockers on contraction of arterial smooth muscle cells (SMCs) and from K+ efflux measurements. Of the classes of K+ channels known to exist in the smooth muscle, the contribution of voltage-gated (KV) and high-conductance, Ca2+ gated K+ (BKCa) channels to the regulation of arterial SMC contractile function has been the most studied in hypertension. The effects of selective and nonselective K+ channel blockers on tonic contraction suggest that these two K+ channel gene families contribute differently to total K+ conductance in arterial SMCs from normal and hypertensive subjects. Direct measurements of K+ channel properties by electrophysiological methods generally support this conclusion. Studies have demonstrated larger BKCa currents in SMCs from several arteries of hypertensive rats, which have been reported to result from a greater Ca2+ sensitivity of BKCa channels and/or from greater protein expression. Some, but not all, studies have shown decreased KV currents in arterial SMCs from hypertensive animals measured under Ca(2+)-replete conditions. However, when external Ca2+ is removed or when Ca2+ influx is inhibited, KV currents are larger in SMCs exposed to chronic hypertension. Gene expression studies of Shaker KV1 transcripts have shown that of the dominant species present in arterial SMCs, KV1.2 expression is higher, whereas KV1.5 is the same in SMCs from hypertensive compared to normal animals. This finding is consistent with the larger KV currents in vascular SMCs from hypertensive animals under low Ca2+ conditions and suggests that Ca2+ influx and/or intracellular Ca2+ per se exerts a greater inhibitory effect on KV currents in the myocytes from these animals. The pathways by which these K+ channel differences are produced during hypertension remain to be elucidated, as does the potential for these channel proteins to be targeted by novel antihypertensive therapies.
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Affiliation(s)
- Robert H Cox
- Lankenau Institute for Medical Research, Jefferson Health System, 100 West Lancaster Avenue, Wynnewood, Philadelphia, PA 19096, USA.
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41
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Michelakis ED, Weir EK. The pathobiology of pulmonary hypertension. Smooth muscle cells and ion channels. Clin Chest Med 2001; 22:419-32. [PMID: 11590838 DOI: 10.1016/s0272-5231(05)70281-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Chronic hypoxic pulmonary arterial hypertension, APAH, and PPAH are characterized by vasoconstriction and vascular remodeling and are associated with decreased Kv currents in PA smooth muscle cells. Although Kv2.1 is less well studied, it seems that Kv1.5 is particularly important in the pulmonary circulation in animals and humans because it has been implicated in physiologic phenomena (HPV) and all of the aforementioned pulmonary hypertensive disorders. This occurrence is perhaps because of the fact that it controls Em in the PA smooth muscle cells and it has a short turnover half time. It is also certain that the pathogenesis of PPAH is multifactorial and not a result of a single abnormality. The recently discovered "PPAH gene" in chromosome 2q in patients with familial PPAH (6%-12% of patients) does not seem to encode for any Kv channels. Kv1.5 abnormalities, however, are likely to be a strong predisposing factor that, in association with others such as endothelial dysfunction, [figure: see text] anorexigen use, or viral infections, will initiate a process that eventually leads to PPAH. The selective Kv1.5 down-regulation leaves wide open the door to replacement gene therapy in pulmonary hypertension research.
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Affiliation(s)
- E D Michelakis
- Department of Medicine, Division of Cardiology, the Vascular Biology Group, University of Alberta, Edmonton, Canada.
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42
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Karkanis T, Jiao Y, Hurley BR, Li S, Pickering JG, Sims SM. Functional receptor-channel coupling compared in contractile and proliferative human vascular smooth muscle. J Cell Physiol 2001; 187:244-55. [PMID: 11268004 DOI: 10.1002/jcp.1069] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
We have previously identified a human vascular smooth muscle clone that can reversibly convert between proliferative and contractile phenotypes. Here we compared receptor-channel coupling in these cells using fura-2 to monitor [Ca(2+)](i) and patch-clamp to record currents. Histamine elevated [Ca(2+)](i) in all cells and caused contraction of cells exhibiting the contractile phenotype. The rise of [Ca(2+)](i) persisted in Ca(2+)-free solution and was abolished by thapsigargin, indicating involvement of stores. Whole cell electrophysiological recording revealed that histamine evoked transient outward K(+) current, indicating functional receptor-channel coupling. The time-course and amplitude of the histamine-activated current were similar in cells of the proliferative and contractile phenotypes. Moreover, a large conductance K(+) channel was recorded in cell-attached patches and was activated by histamine as well as the Ca(2+) ionophore A-23187, identifying it as the large conductance Ca(2+)-dependent K(+) channel. This K(+) channel showed similar characteristics and activation in both proliferative and contractile phenotypes, indicating that expression was independent of phenotype. In contrast, histamine also elicited an inward Cl(-) current in some contractile cells, suggesting differential regulation of this current depending on phenotype. These studies demonstrate the usefulness of this human vascular cell clone for studying functional plasticity of smooth muscle, while avoiding complications arising from extended times in culture.
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Affiliation(s)
- T Karkanis
- Department of Physiology, The University of Western Ontario, London, Ontario, Canada
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43
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Abstract
Anorectic drugs have been used for more than 30 years as an aid in weight reduction for obese persons. The use of aminorex, an amphetamine analog that increases norepinephrine levels in the central nervous system, led to an epidemic of primary pulmonary hypertension (PPH) in Europe in the late 1960s and early 1970s. The use of fenfluramine and later dexfenfluramine [drugs that inhibit 5-hydroxytryptamine (5-HT) release and reuptake and increases 5-HT and thus 5-HT secretion in the brain] was associated with a second epidemic of PPH. All of these drugs have been voluntarily withdrawn from the market. The pathogenesis of PPH in patients treated with these agents is uncertain, but recent evidence suggests that potassium channel abnormalities and vasoactive and proliferative properties of 5-HT may play a role. There is increasing experimental evidence suggesting that aminorex, fenfluramine and dexfenfluramine inhibit 4-aminopyridine-sensitive currents in potassium channels resulting in vasoconstriction in pulmonary resistance vessels and perhaps smooth muscle cell proliferation. 5-HT causes pulmonary artery vasoconstriction and smooth muscle cell proliferation. Its levels are known to be high in those with fenfluramine-induced PPH. However, a firm cause-and-effect relationship has not yet been established. One potentially beneficial effect of the epidemics of anorectic-related PPH is that it may have provided important insights into the causes of PPH unrelated to anorectic agents.
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Affiliation(s)
- E D Michelakis
- Department of Medicine, University of Alberta, Edmonton, Canada.
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44
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Tang XD, Daggett H, Hanner M, Garcia ML, McManus OB, Brot N, Weissbach H, Heinemann SH, Hoshi T. Oxidative regulation of large conductance calcium-activated potassium channels. J Gen Physiol 2001; 117:253-74. [PMID: 11222629 PMCID: PMC2225619 DOI: 10.1085/jgp.117.3.253] [Citation(s) in RCA: 114] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Reactive oxygen/nitrogen species are readily generated in vivo, playing roles in many physiological and pathological conditions, such as Alzheimer's disease and Parkinson's disease, by oxidatively modifying various proteins. Previous studies indicate that large conductance Ca(2+)-activated K(+) channels (BK(Ca) or Slo) are subject to redox regulation. However, conflicting results exist whether oxidation increases or decreases the channel activity. We used chloramine-T, which preferentially oxidizes methionine, to examine the functional consequences of methionine oxidation in the cloned human Slo (hSlo) channel expressed in mammalian cells. In the virtual absence of Ca(2+), the oxidant shifted the steady-state macroscopic conductance to a more negative direction and slowed deactivation. The results obtained suggest that oxidation enhances specific voltage-dependent opening transitions and slows the rate-limiting closing transition. Enhancement of the hSlo activity was partially reversed by the enzyme peptide methionine sulfoxide reductase, suggesting that the upregulation is mediated by methionine oxidation. In contrast, hydrogen peroxide and cysteine-specific reagents, DTNB, MTSEA, and PCMB, decreased the channel activity. Chloramine-T was much less effective when concurrently applied with the K(+) channel blocker TEA, which is consistent with the possibility that the target methionine lies within the channel pore. Regulation of the Slo channel by methionine oxidation may represent an important link between cellular electrical excitability and metabolism.
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Affiliation(s)
- Xiang D. Tang
- Department of Physiology and Biophysics, The University of Iowa, Iowa City, Iowa 52242
| | - Heather Daggett
- Department of Physiology and Biophysics, The University of Iowa, Iowa City, Iowa 52242
| | - Markus Hanner
- Merck Research Laboratories, Rahway, New Jersey 07065
| | | | | | - Nathan Brot
- Hospital for Special Surgery, Cornell University Medical Center, New York, New York 10021
| | - Herbert Weissbach
- Center for Molecular Biology and Biotechnology, Florida Atlantic University, Boca Raton, Florida 33431
| | - Stefan H. Heinemann
- AG Molekulare und Zelluläre Biophysik am Klinikum der Universitat Jena, D-07447 Jena, Germany
| | - Toshinori Hoshi
- Department of Physiology and Biophysics, The University of Iowa, Iowa City, Iowa 52242
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45
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Abstract
Potassium ion (K(+)) channel activity is a major regulator of vascular muscle cell membrane potential (E(m)) and is therefore an important determinant of vascular tone. There is growing evidence that the function of several types of vascular K(+) channels is altered during major cardiovascular diseases, such as chronic hypertension, diabetes, and atherosclerosis. Vasoconstriction and the compromised ability of an artery to dilate are likely consequences of defective K(+) channel function in blood vessels during these disease states. In some instances, increased K(+) channel function may help to compensate for increased vascular tone. Endothelial cell dysfunction is commonly associated with cardiovascular disease, and altered activity of nitric oxide, prostacyclin, and endothelium-derived hyperpolarizing factor could also contribute to changes in resting K(+) channel activity, E(m), and K(+) channel-mediated vasodilatation. Our current knowledge of the effects of disease on vascular K(+) channel function almost exclusively relies on interpretation of data obtained by using pharmacological modulators of K(+) channels. As further progress is made in the development of more selective drugs and through molecular approaches such as gene targeting technology in mice, specific K(+) channel abnormalities and their causes in particular diseases should be more readily identified, providing novel directions for vascular therapy.
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Affiliation(s)
- C G Sobey
- Department of Pharmacology, The University of Melbourne, Parkville, Victoria, Australia.
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46
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Abstract
The control and maintenance of vascular tone is due to a balance between vasoconstrictor and vasodilator pathways. Vasomotor responses to neural, metabolic and physical factors vary between vessels in different vascular beds, as well as along the same bed, particularly as vessels become smaller. These differences result from variation in the composition of neurotransmitters released by perivascular nerves, variation in the array and activation of receptor subtypes expressed in different vascular beds and variation in the signal transduction pathways activated in either the vascular smooth muscle or endothelial cells. As the study of vasomotor responses often requires pre-existing tone, some of the reported heterogeneity in the relative contributions of different vasodilator mechanisms may be compounded by different experimental conditions. Biochemical variations, such as the expression of ion channels, connexin subtypes and other important components of second messenger cascades, have been documented in the smooth muscle and endothelial cells in different parts of the body. Anatomical variations, in the presence and prevalence of gap junctions between smooth muscle cells, between endothelial cells and at myoendothelial gap junctions, between the two cell layers, have also been described. These factors will contribute further to the heterogeneity in local and conducted responses.
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Affiliation(s)
- C E Hill
- Autonomic Synapse Group, Division of Neuroscience, John Curtin School of Medical Research, Australian National University, Canberra 0200 ACT, Australia.
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47
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MacLean MR, Herve P, Eddahibi S, Adnot S. 5-hydroxytryptamine and the pulmonary circulation: receptors, transporters and relevance to pulmonary arterial hypertension. Br J Pharmacol 2000; 131:161-8. [PMID: 10991906 PMCID: PMC1572323 DOI: 10.1038/sj.bjp.0703570] [Citation(s) in RCA: 184] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- M R MacLean
- Division of Neuroscience and Biomedical Systems, Institute of Biomedical and Life Sciences, University of Glasgow, G12 8QQ. UPRES
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48
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Scholfield CN, Curtis TM. Heterogeneity in cytosolic calcium regulation among different microvascular smooth muscle cells of the rat retina. Microvasc Res 2000; 59:233-42. [PMID: 10684729 DOI: 10.1006/mvre.1999.2227] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Rat retinae were dissociated to yield intact microvessels 7 to 42 microm in diameter. These were loaded with fura-2 AM and single fragments anchored down in a recording bath. Intracellular Ca(2+) levels from 20- to 30-microm sections of vessel were estimated by microfluorimetry. The vessels studied were identified as metarterioles and arterioles. Only the microvascular smooth muscle cells loaded with fura-2 AM and changes in the fluorescence signal were confined to these cells: Endothelial cells did not make any contribution to the fluorescence signal nor did they contribute to the actions of the drugs. Caffeine (10 mM) or elevated K(+) (100 mM) produced a transient rise in cell Ca(2+) in the larger vessels (diameters >18 microm) but had no effect on smaller vessels (diameters <18 microm). Rises in cell Ca(2+) were accompanied by a rapid ( approximately 2 s to peak) contraction followed by relaxation. Caffeine and K(+) responses were blocked by ryanodine (10 microM) and nifedipine (1 microM), respectively. In all the vessels tested, vasopressin (arginine, 10 nM) elicited a transient increase in cell Ca(2+) and a constriction, irrespective of the diameter of the vessel. All vessels tested also responded to endothelin-1 (1-10 nM) through an Et(A) receptor to produce a transient rise in cell Ca(2+) followed by a plateau phase of elevated Ca(2+) and a constriction. In contrast to the transient effects of vasopressin, caffeine, and K(+), the cell Ca(2+) remained elevated (>30 min) on washing out the endothelin and the vessel failed to relax. These results demonstrate heterogeneity between smaller and larger retinal vessels with regard to Ca(2+) mobilisation and homogeneity with respect to the actions of vasoactive peptides.
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MESH Headings
- Animals
- Arginine Vasopressin/pharmacology
- Arterioles/metabolism
- Caffeine/pharmacology
- Calcium/metabolism
- Calcium Channels, L-Type/drug effects
- Calcium Channels, L-Type/metabolism
- Female
- Ion Transport
- Male
- Microcirculation
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Potassium/pharmacology
- Rats
- Rats, Sprague-Dawley
- Receptor, Endothelin A
- Receptors, Endothelin/drug effects
- Retinal Artery/metabolism
- Ryanodine/pharmacology
- Ryanodine Receptor Calcium Release Channel/drug effects
- Ryanodine Receptor Calcium Release Channel/metabolism
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Affiliation(s)
- C N Scholfield
- Smooth muscle group, Department of Physiology, Queens University, 97, Lisburn Road, Belfast, BT9 7BL, United Kingdom.
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49
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Xu C, Lu Y, Tang G, Wang R. Expression of voltage-dependent K(+) channel genes in mesenteric artery smooth muscle cells. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 277:G1055-63. [PMID: 10564112 DOI: 10.1152/ajpgi.1999.277.5.g1055] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Abstract
Molecular basis of native voltage-dependent K(+) (Kv) channels in smooth muscle cells (SMCs) from rat mesenteric arteries was investigated. The whole cell patch-clamp study revealed that a 4-aminopyridine-sensitive delayed rectifier K(+) current (I(K)) was the predominant K(+) conductance in these cells. A systematic screening of the expression of 18 Kv channel genes using RT-PCR technique showed that six I(K)-encoding genes (Kv1.2, Kv1.3, Kv1.5, Kv2.1, Kv2.2, and Kv3.2) were expressed in mesenteric artery. Although no transient outward Kv currents (I(A)) were recorded in the studied SMCs, transcripts of multiple I(A)-encoding genes, including Kv1.4, Kv3.3, Kv3.4, Kv4.1, Kv4.2, and Kv4.3 as well as I(A)-facilitating Kv beta-subunits (Kvbeta1, Kvbeta2, and Kvbeta3), were detected in mesenteric arteries. Western blot analysis demonstrated that four I(K)-related Kv channel proteins (Kv1.2, Kv1. 3, Kv1.5, and Kv2.1) were detected in mesenteric artery tissues. The presence of Kv1.2, Kv1.3, Kv1.5, and Kv2.1 channel proteins in isolated SMCs was further confirmed by immunocytochemistry study. Our results suggest that the native I(K) in rat mesenteric artery SMCs might be generated by heteromultimerization of Kv genes.
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MESH Headings
- 4-Aminopyridine/pharmacology
- Animals
- Blotting, Western
- Brain Chemistry
- DNA Probes
- Delayed Rectifier Potassium Channels
- Electric Stimulation
- Ether-A-Go-Go Potassium Channels
- Gene Expression/physiology
- Ion Channel Gating/drug effects
- Ion Channel Gating/physiology
- Kv1.3 Potassium Channel
- Kv1.4 Potassium Channel
- Kv1.5 Potassium Channel
- Male
- Membrane Potentials/drug effects
- Membrane Potentials/physiology
- Mesenteric Arteries/chemistry
- Mesenteric Arteries/cytology
- Mesenteric Arteries/innervation
- Muscle, Smooth, Vascular/chemistry
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/innervation
- Neurons/chemistry
- Neurons/physiology
- Patch-Clamp Techniques
- Potassium Channels/analysis
- Potassium Channels/genetics
- Potassium Channels, Voltage-Gated
- RNA, Messenger/analysis
- Rats
- Rats, Sprague-Dawley
- Reverse Transcriptase Polymerase Chain Reaction
- Shab Potassium Channels
- Shal Potassium Channels
- Shaw Potassium Channels
- Sympathetic Nervous System/chemistry
- Sympathetic Nervous System/cytology
- Tetraethylammonium/pharmacology
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Affiliation(s)
- C Xu
- Department of Physiology, College of Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 5E5
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50
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Ren J, Zhang L, Benishin CG. Parathyroid hypertensive factor inhibits voltage-gated K+ channels in vascular smooth muscle cells. Can J Physiol Pharmacol 1999. [DOI: 10.1139/y99-098] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Parathyroid hypertensive factor (PHF) has been implicated in regulation of vascular smooth muscle tone and pathogenesis of several forms of hypertension. Earlier studies have suggested that PHF enhances the actions of other vasoconstrictors, while it has no in vitro vasoconstrictor property of its own. PHF was previously found to enhance the L-type Ca channel currents and intracellular Ca responses to depolarization in vascular smooth muscle cells (VSMCs). The present study examined whether PHF might act on K channels in the plasma membrane of VSMCs. Primary cultured VSMCs from rat tail artery were used. The whole-cell version of the patch-clamp technique was used under conditions in which there was no contribution of Ca-activated K channels to the outward current. Both purified and semipurified PHF inhibited the delayed rectifier type potassium current in a dose-dependent manner. The effect was time dependent and was first significantly different from the control current after 30 min. The inhibition of the delayed rectifier K channel was associated with a time-dependent decrease in the resting membrane potential. Therefore, PHF may alter VSMC cellular Ca responses by reducing the membrane potential to a level closer to the activation potential of Ca channels.Key words: parathyroid hypertensive factor, hypertension, potassium channels, vascular smooth muscle, membrane potential.
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