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Pries AR, Badimon L, Bugiardini R, Camici PG, Dorobantu M, Duncker DJ, Escaned J, Koller A, Piek JJ, de Wit C. Coronary vascular regulation, remodelling, and collateralization: mechanisms and clinical implications on behalf of the working group on coronary pathophysiology and microcirculation. Eur Heart J 2015; 36:3134-46. [DOI: 10.1093/eurheartj/ehv100] [Citation(s) in RCA: 133] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Accepted: 03/13/2015] [Indexed: 12/31/2022] Open
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102
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Gokina NI, Bonev AD, Phillips J, Gokin AP, Veilleux K, Oppenheimer K, Goloman G. Impairment of IKCa channels contributes to uteroplacental endothelial dysfunction in rat diabetic pregnancy. Am J Physiol Heart Circ Physiol 2015; 309:H592-604. [PMID: 26092991 DOI: 10.1152/ajpheart.00901.2014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 06/19/2015] [Indexed: 12/18/2022]
Abstract
Diabetes in rat pregnancy is associated with impaired vasodilation of the maternal uteroplacental vasculature. In the present study, we explored the role of endothelial cell (EC) Ca(2+)-activated K(+) channels of small conductance (SKCa channels) and intermediate conductance (IKCa channels) in diabetes-induced uterine vascular dysfunction. Diabetes was induced by injection of streptozotocin to second-day pregnant rats and confirmed by the development of maternal hyperglycemia. Control rats were injected with citrate buffer. Changes in smooth muscle cell intracellular Ca(2+) concentration, membrane potential, and vasodilation induced by SKCa/IKCa channel activators were studied in uteroplacental arteries of control and diabetic rats. The impact of diabetes on SKCa- and IKCa-mediated currents was explored in freshly dissociated ECs. NS309 evoked a potent vasodilation that was effectively inhibited by TRAM-34 but not by apamin. NS309-induced smooth muscle cell intracellular Ca(2+) concentration, membrane potential, and dilator responses were significantly diminished by diabetes; N-cyclohexyl-N-2-(3,5-dimethyl-pyrazol-1-yl)-6-methyl-4-pyrimidinamine (CyPPA)-evoked responses were not affected. Ca(2+)-activated ion currents in ECs were insensitive to paxilline, markedly inhibited by charybdotoxin (ChTX), and diminished by apamin. NS309-induced EC currents were generated mostly due to activation of ChTX-sensitive channels. Maternal diabetes resulted in a significant reduction in ChTX-sensitive currents with no effect on apamin-sensitive or CyPPA-induced currents. We concluded that IKCa channels play a prevalent role over SKCa channels in the generation of endothelial K(+) currents and vasodilation of uteroplacental arteries. Impaired function of IKCa channels importantly contributes to diabetes-induced uterine endothelial dysfunction. Therapeutic restoration of IKCa channel function may be a novel strategy for improvement of maternal uteroplacental blood flow in pregnancies complicated by diabetes.
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Affiliation(s)
- Natalia I Gokina
- Department of Obstetrics, Gynecology and Reproductive Sciences, College of Medicine, University of Vermont, Burlington, Vermont; and
| | - Adrian D Bonev
- Department of Pharmacology, College of Medicine, University of Vermont, Burlington, Vermont
| | - Julie Phillips
- Department of Obstetrics, Gynecology and Reproductive Sciences, College of Medicine, University of Vermont, Burlington, Vermont; and
| | - Alexander P Gokin
- Department of Obstetrics, Gynecology and Reproductive Sciences, College of Medicine, University of Vermont, Burlington, Vermont; and
| | - Kelsey Veilleux
- Department of Obstetrics, Gynecology and Reproductive Sciences, College of Medicine, University of Vermont, Burlington, Vermont; and
| | - Karen Oppenheimer
- Department of Obstetrics, Gynecology and Reproductive Sciences, College of Medicine, University of Vermont, Burlington, Vermont; and
| | - Gabriela Goloman
- Department of Obstetrics, Gynecology and Reproductive Sciences, College of Medicine, University of Vermont, Burlington, Vermont; and
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103
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Zhou XB, Feng YX, Sun Q, Lukowski R, Qiu Y, Spiger K, Li Z, Ruth P, Korth M, Skolnik EY, Borggrefe M, Dobrev D, Wieland T. Nucleoside diphosphate kinase B-activated intermediate conductance potassium channels are critical for neointima formation in mouse carotid arteries. Arterioscler Thromb Vasc Biol 2015; 35:1852-61. [PMID: 26088577 DOI: 10.1161/atvbaha.115.305881] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Accepted: 05/29/2015] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Vascular smooth muscle cells (VSMC) proliferation is a hallmark of atherosclerosis and vascular restenosis. The intermediate conductance Ca(2+)-activated K(+) (SK4) channel is required for pathological VSMC proliferation. In T lymphocytes, nucleoside diphosphate kinase B (NDPKB) has been implicated in SK4 channel activation. We thus investigated the role of NDPKB in the regulation of SK4 currents (ISK4) in proliferating VSMC and neointima formation. APPROACH AND RESULTS Function and expression of SK4 channels in VSMC from injured mouse carotid arteries were assessed by patch-clamping and real-time polymerase chain reaction. ISK4 was detectable in VSMC from injured but not from uninjured arteries correlating with the occurrence of the proliferative phenotype. Direct application of NDPKB to the membrane of inside-out patches increased ISK4, whereas NDPKB did not alter currents in VSMC obtained from injured vessels of SK4-deficient mice. The NDPKB-induced increase in ISK4 was prevented by protein histidine phosphatase 1, but not an inactive protein histidine phosphatase 1 mutant indicating that ISK4 is regulated via histidine phosphorylation in proliferating VSMC; moreover, genetic NDPKB ablation reduced ISK4 by 50% suggesting a constitutive activation of ISK4 in proliferating VSMC. In line, neointima formation after wire injury of the carotid artery was substantially reduced in mice deficient in SK4 channels or NDPKB. CONCLUSIONS NDPKB to SK4 signaling is required for neointima formation. Constitutive activation of SK4 by NDPKB in proliferating VSMC suggests that targeting this interaction via, for example, activation of protein histidine phosphatase 1 may provide clinically meaningful effects in vasculoproliferative diseases such as atherosclerosis and post angioplasty restenosis.
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Affiliation(s)
- Xiao-Bo Zhou
- From the 1st Medical Clinic (X.B.-Z., M.B.), Institute of Experimental and Clinical Pharmacology and Toxicology (Y.-X.F., Y.Q., K.S., T.W.), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany; Institute of Pharmacology, West German Heart and Vessel Centre, University Duisburg-Essen, Essen, Germany (Q.S., D.D.); Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany (R.L., P.R.); Center for Experimental Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (M.K.); Department of Medicine (Z.L., E.Y.S.) and Department of Pharmacology (Z.L., E.Y.S.), Langone Medical Center, New York University; and DZHK (German Center for Cardiovascular Research), Partner Site Heidelberg-Mannheim, Germany (M.B., T.W.)
| | - Yu-Xi Feng
- From the 1st Medical Clinic (X.B.-Z., M.B.), Institute of Experimental and Clinical Pharmacology and Toxicology (Y.-X.F., Y.Q., K.S., T.W.), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany; Institute of Pharmacology, West German Heart and Vessel Centre, University Duisburg-Essen, Essen, Germany (Q.S., D.D.); Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany (R.L., P.R.); Center for Experimental Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (M.K.); Department of Medicine (Z.L., E.Y.S.) and Department of Pharmacology (Z.L., E.Y.S.), Langone Medical Center, New York University; and DZHK (German Center for Cardiovascular Research), Partner Site Heidelberg-Mannheim, Germany (M.B., T.W.)
| | - Qiang Sun
- From the 1st Medical Clinic (X.B.-Z., M.B.), Institute of Experimental and Clinical Pharmacology and Toxicology (Y.-X.F., Y.Q., K.S., T.W.), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany; Institute of Pharmacology, West German Heart and Vessel Centre, University Duisburg-Essen, Essen, Germany (Q.S., D.D.); Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany (R.L., P.R.); Center for Experimental Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (M.K.); Department of Medicine (Z.L., E.Y.S.) and Department of Pharmacology (Z.L., E.Y.S.), Langone Medical Center, New York University; and DZHK (German Center for Cardiovascular Research), Partner Site Heidelberg-Mannheim, Germany (M.B., T.W.)
| | - Robert Lukowski
- From the 1st Medical Clinic (X.B.-Z., M.B.), Institute of Experimental and Clinical Pharmacology and Toxicology (Y.-X.F., Y.Q., K.S., T.W.), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany; Institute of Pharmacology, West German Heart and Vessel Centre, University Duisburg-Essen, Essen, Germany (Q.S., D.D.); Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany (R.L., P.R.); Center for Experimental Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (M.K.); Department of Medicine (Z.L., E.Y.S.) and Department of Pharmacology (Z.L., E.Y.S.), Langone Medical Center, New York University; and DZHK (German Center for Cardiovascular Research), Partner Site Heidelberg-Mannheim, Germany (M.B., T.W.)
| | - Yi Qiu
- From the 1st Medical Clinic (X.B.-Z., M.B.), Institute of Experimental and Clinical Pharmacology and Toxicology (Y.-X.F., Y.Q., K.S., T.W.), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany; Institute of Pharmacology, West German Heart and Vessel Centre, University Duisburg-Essen, Essen, Germany (Q.S., D.D.); Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany (R.L., P.R.); Center for Experimental Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (M.K.); Department of Medicine (Z.L., E.Y.S.) and Department of Pharmacology (Z.L., E.Y.S.), Langone Medical Center, New York University; and DZHK (German Center for Cardiovascular Research), Partner Site Heidelberg-Mannheim, Germany (M.B., T.W.)
| | - Katharina Spiger
- From the 1st Medical Clinic (X.B.-Z., M.B.), Institute of Experimental and Clinical Pharmacology and Toxicology (Y.-X.F., Y.Q., K.S., T.W.), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany; Institute of Pharmacology, West German Heart and Vessel Centre, University Duisburg-Essen, Essen, Germany (Q.S., D.D.); Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany (R.L., P.R.); Center for Experimental Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (M.K.); Department of Medicine (Z.L., E.Y.S.) and Department of Pharmacology (Z.L., E.Y.S.), Langone Medical Center, New York University; and DZHK (German Center for Cardiovascular Research), Partner Site Heidelberg-Mannheim, Germany (M.B., T.W.)
| | - Zhai Li
- From the 1st Medical Clinic (X.B.-Z., M.B.), Institute of Experimental and Clinical Pharmacology and Toxicology (Y.-X.F., Y.Q., K.S., T.W.), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany; Institute of Pharmacology, West German Heart and Vessel Centre, University Duisburg-Essen, Essen, Germany (Q.S., D.D.); Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany (R.L., P.R.); Center for Experimental Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (M.K.); Department of Medicine (Z.L., E.Y.S.) and Department of Pharmacology (Z.L., E.Y.S.), Langone Medical Center, New York University; and DZHK (German Center for Cardiovascular Research), Partner Site Heidelberg-Mannheim, Germany (M.B., T.W.)
| | - Peter Ruth
- From the 1st Medical Clinic (X.B.-Z., M.B.), Institute of Experimental and Clinical Pharmacology and Toxicology (Y.-X.F., Y.Q., K.S., T.W.), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany; Institute of Pharmacology, West German Heart and Vessel Centre, University Duisburg-Essen, Essen, Germany (Q.S., D.D.); Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany (R.L., P.R.); Center for Experimental Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (M.K.); Department of Medicine (Z.L., E.Y.S.) and Department of Pharmacology (Z.L., E.Y.S.), Langone Medical Center, New York University; and DZHK (German Center for Cardiovascular Research), Partner Site Heidelberg-Mannheim, Germany (M.B., T.W.)
| | - Michael Korth
- From the 1st Medical Clinic (X.B.-Z., M.B.), Institute of Experimental and Clinical Pharmacology and Toxicology (Y.-X.F., Y.Q., K.S., T.W.), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany; Institute of Pharmacology, West German Heart and Vessel Centre, University Duisburg-Essen, Essen, Germany (Q.S., D.D.); Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany (R.L., P.R.); Center for Experimental Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (M.K.); Department of Medicine (Z.L., E.Y.S.) and Department of Pharmacology (Z.L., E.Y.S.), Langone Medical Center, New York University; and DZHK (German Center for Cardiovascular Research), Partner Site Heidelberg-Mannheim, Germany (M.B., T.W.)
| | - Edward Y Skolnik
- From the 1st Medical Clinic (X.B.-Z., M.B.), Institute of Experimental and Clinical Pharmacology and Toxicology (Y.-X.F., Y.Q., K.S., T.W.), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany; Institute of Pharmacology, West German Heart and Vessel Centre, University Duisburg-Essen, Essen, Germany (Q.S., D.D.); Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany (R.L., P.R.); Center for Experimental Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (M.K.); Department of Medicine (Z.L., E.Y.S.) and Department of Pharmacology (Z.L., E.Y.S.), Langone Medical Center, New York University; and DZHK (German Center for Cardiovascular Research), Partner Site Heidelberg-Mannheim, Germany (M.B., T.W.)
| | - Martin Borggrefe
- From the 1st Medical Clinic (X.B.-Z., M.B.), Institute of Experimental and Clinical Pharmacology and Toxicology (Y.-X.F., Y.Q., K.S., T.W.), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany; Institute of Pharmacology, West German Heart and Vessel Centre, University Duisburg-Essen, Essen, Germany (Q.S., D.D.); Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany (R.L., P.R.); Center for Experimental Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (M.K.); Department of Medicine (Z.L., E.Y.S.) and Department of Pharmacology (Z.L., E.Y.S.), Langone Medical Center, New York University; and DZHK (German Center for Cardiovascular Research), Partner Site Heidelberg-Mannheim, Germany (M.B., T.W.)
| | - Dobromir Dobrev
- From the 1st Medical Clinic (X.B.-Z., M.B.), Institute of Experimental and Clinical Pharmacology and Toxicology (Y.-X.F., Y.Q., K.S., T.W.), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany; Institute of Pharmacology, West German Heart and Vessel Centre, University Duisburg-Essen, Essen, Germany (Q.S., D.D.); Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany (R.L., P.R.); Center for Experimental Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (M.K.); Department of Medicine (Z.L., E.Y.S.) and Department of Pharmacology (Z.L., E.Y.S.), Langone Medical Center, New York University; and DZHK (German Center for Cardiovascular Research), Partner Site Heidelberg-Mannheim, Germany (M.B., T.W.)
| | - Thomas Wieland
- From the 1st Medical Clinic (X.B.-Z., M.B.), Institute of Experimental and Clinical Pharmacology and Toxicology (Y.-X.F., Y.Q., K.S., T.W.), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany; Institute of Pharmacology, West German Heart and Vessel Centre, University Duisburg-Essen, Essen, Germany (Q.S., D.D.); Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany (R.L., P.R.); Center for Experimental Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (M.K.); Department of Medicine (Z.L., E.Y.S.) and Department of Pharmacology (Z.L., E.Y.S.), Langone Medical Center, New York University; and DZHK (German Center for Cardiovascular Research), Partner Site Heidelberg-Mannheim, Germany (M.B., T.W.).
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104
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Sacerdoti D, Pesce P, Di Pascoli M, Brocco S, Cecchetto L, Bolognesi M. Arachidonic acid metabolites and endothelial dysfunction of portal hypertension. Prostaglandins Other Lipid Mediat 2015; 120:80-90. [PMID: 26072731 DOI: 10.1016/j.prostaglandins.2015.05.008] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Revised: 05/20/2015] [Accepted: 05/25/2015] [Indexed: 12/12/2022]
Abstract
Increased resistance to portal flow and increased portal inflow due to mesenteric vasodilatation represent the main factors causing portal hypertension in cirrhosis. Endothelial cell dysfunction, defined as an imbalance between the synthesis, release, and effect of endothelial mediators of vascular tone, inflammation, thrombosis, and angiogenesis, plays a major role in the increase of resistance in portal circulation, in the decrease in the mesenteric one, in the development of collateral circulation. Reduced response to vasodilators in liver sinusoids and increased response in the mesenteric arterioles, and, viceversa, increased response to vasoconstrictors in the portal-sinusoidal circulation and decreased response in the mesenteric arterioles are also relevant to the pathophysiology of portal hypertension. Arachidonic acid (AA) metabolites through the three pathways, cyclooxygenase (COX), lipoxygenase, and cytochrome P450 monooxygenase and epoxygenase, are involved in endothelial dysfunction of portal hypertension. Increased thromboxane-A2 production by liver sinusoidal endothelial cells (LSECs) via increased COX-1 activity/expression, increased leukotriens, increased epoxyeicosatrienoic acids (EETs) (dilators of the peripheral arterial circulation, but vasoconstrictors of the portal-sinusoidal circulation), represent a major component in the increased portal resistance, in the decreased portal response to vasodilators and in the hyper-response to vasoconstrictors. Increased prostacyclin (PGI2) via COX-1 and COX-2 overexpression, and increased EETs/heme-oxygenase-1/K channels/gap junctions (endothelial derived hyperpolarizing factor system) play a major role in mesenteric vasodilatation, hyporeactivity to vasoconstrictors, and hyper-response to vasodilators. EETs, mediators of liver regeneration after hepatectomy and of angiogenesis, may play a role in the development of regenerative nodules and collateral circulation, through stimulation of vascular endothelial growth factor (VEGF) inside the liver and in the portal circulation. Pharmacological manipulation of AA metabolites may be beneficial for cirrhotic portal hypertension.
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Affiliation(s)
- David Sacerdoti
- Department of Medicine, University of Padova Via Giustiniani, 2, 35100 Padova, Italy.
| | - Paola Pesce
- Department of Medicine, University of Padova Via Giustiniani, 2, 35100 Padova, Italy
| | - Marco Di Pascoli
- Department of Medicine, University of Padova Via Giustiniani, 2, 35100 Padova, Italy
| | - Silvia Brocco
- Department of Medicine, University of Padova Via Giustiniani, 2, 35100 Padova, Italy
| | - Lara Cecchetto
- Department of Medicine, University of Padova Via Giustiniani, 2, 35100 Padova, Italy
| | - Massimo Bolognesi
- Department of Medicine, University of Padova Via Giustiniani, 2, 35100 Padova, Italy
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105
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Al-Brakati AY, Kamishima T, Dart C, Quayle JM. Caveolar disruption causes contraction of rat femoral arteries via reduced basal NO release and subsequent closure of BKCa channels. PeerJ 2015; 3:e966. [PMID: 26038721 PMCID: PMC4451037 DOI: 10.7717/peerj.966] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Accepted: 04/29/2015] [Indexed: 12/22/2022] Open
Abstract
Background and Purpose. Caveolae act as signalling hubs in endothelial and smooth muscle cells. Caveolar disruption by the membrane cholesterol depleting agent methyl-β-cyclodextrin (M-β-CD) has various functional effects on arteries including (i) impairment of endothelium-dependent relaxation, and (ii) alteration of smooth muscle cell (SMC) contraction independently of the endothelium. The aim of this study was to explore the effects of M-β-CD on rat femoral arteries. Methods. Isometric force was measured in rat femoral arteries stimulated to contract with a solution containing 20 mM K(+) and 200 nM Bay K 8644 (20 K/Bay K) or with one containing 80 mM K(+)(80 K). Results. Incubation of arteries with M-β-CD (5 mM, 60 min) increased force in response to 20 K/Bay K but not that induced by 80 K. Application of cholesterol saturated M-β-CD (Ch-MCD, 5 mM, 50 min) reversed the effects of M-β-CD. After mechanical removal of endothelial cells M-β-CD caused only a small enhancement of contractions to 20 K/Bay K. This result suggests M-β-CD acts via altering release of an endothelial-derived vasodilator or vasoconstrictor. When nitric oxide synthase was blocked by pre-incubation of arteries with L-NAME (250 µM) the contraction of arteries to 20 K/Bay K was enhanced, and this effect was abolished by pre-treatment with M-β-CD. This suggests M-β-CD is inhibiting endothelial NO release. Inhibition of large conductance voltage- and Ca(2+)-activated (BKCa) channels with 2 mM TEA(+) or 100 nM Iberiotoxin (IbTX) enhanced 20 K/Bay K contractions. L-NAME attenuated the contractile effect of IbTX, as did endothelial removal. Conclusions. Our results suggest caveolar disruption results in decreased release of endothelial-derived nitric oxide in rat femoral artery, resulting in a reduced contribution of BKCa channels to the smooth muscle cell membrane potential, causing depolarisation and contraction.
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Affiliation(s)
- AY Al-Brakati
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, UK
| | - T Kamishima
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, UK
| | - C Dart
- Department of Biochemistry and Cell Biology, Institute of Integrative Biology, University of Liverpool, Liverpool, UK
| | - JM Quayle
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, UK
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106
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More AS, Mishra JS, Hankins GDV, Yallampalli C, Sathishkumar K. Enalapril Normalizes Endothelium-Derived Hyperpolarizing Factor-Mediated Relaxation in Mesenteric Artery of Adult Hypertensive Rats Prenatally Exposed to Testosterone. Biol Reprod 2015; 92:155. [PMID: 25972013 DOI: 10.1095/biolreprod.115.130468] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Accepted: 05/07/2015] [Indexed: 12/19/2022] Open
Abstract
Prenatal exposure to elevated testosterone levels induces adult life hypertension associated with selective impairments in endothelium-derived hyperpolarizing factor (EDHF)-mediated relaxation in mesenteric arteries. We tested whether the angiotensin-converting enzyme inhibitor enalapril restores EDHF function through regulating the activities of small (Kcnn3) and intermediate (Kcnn4) conductance calcium-activated potassium channels in mesenteric arteries. Pregnant Sprague-Dawley rats were injected subcutaneously with vehicle or testosterone propionate (0.5 mg/kg/day from Gestation Day 15 to 19), and their 6-mo-old adult male offspring were examined. A subset of rats in these two groups was given enalapril (40 mg/kg/day) for 2 wk through drinking water. Blood pressures were assessed through carotid arterial catheter and endothelium-dependent mesenteric arterial EDHF relaxation, using wire myography. Ace and Kcnn3 and Kcnn4 channel expression levels were also examined. Renal and vascular Ace expression and plasma angiotensin II levels were increased in testosterone offspring. Blood pressure levels were significantly higher in testosterone offspring than in controls, and treatment with enalapril significantly attenuated blood pressure in testosterone offspring. EDHF relaxation in testosterone offspring was reduced compared to that in controls, and it was significantly restored by enalapril treatment. Kcnn4 channel expression and function were similar between control and testosterone rats, but it was not affected by enalapril treatment. Relaxation mediated by Kcnn3 was impaired in testosterone offspring, and it was normalized by enalapril treatment. Furthermore, enalapril treatment restored expression levels of Kcnn3 channels. These findings suggest that enalapril has a positive influence on endothelial function with improvement in EDHF relaxation through normalization of Kcnn3 expression and activity.
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Affiliation(s)
- Amar S More
- Division of Reproductive Endocrinology, Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston, Texas
| | - Jay S Mishra
- Division of Reproductive Endocrinology, Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston, Texas
| | - Gary D V Hankins
- Division of Reproductive Endocrinology, Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston, Texas
| | - Chandra Yallampalli
- Department of Obstetrics and Gynecology, Baylor College of Medicine, Houston, Texas
| | - Kunju Sathishkumar
- Division of Reproductive Endocrinology, Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston, Texas
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Szewczyk A, Jarmuszkiewicz W, Koziel A, Sobieraj I, Nobik W, Lukasiak A, Skup A, Bednarczyk P, Drabarek B, Dymkowska D, Wrzosek A, Zablocki K. Mitochondrial mechanisms of endothelial dysfunction. Pharmacol Rep 2015; 67:704-10. [PMID: 26321271 DOI: 10.1016/j.pharep.2015.04.009] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Revised: 04/10/2015] [Accepted: 04/14/2015] [Indexed: 01/09/2023]
Abstract
Endothelial cells play an important physiological role in vascular homeostasis. They are also the first barrier that separates blood from deeper layers of blood vessels and extravascular tissues. Thus, they are exposed to various physiological blood components as well as challenged by pathological stimuli, which may exert harmful effects on the vascular system by stimulation of excessive generation of reactive oxygen species (ROS). The major sources of ROS are NADPH oxidase and mitochondrial respiratory chain complexes. Modulation of mitochondrial energy metabolism in endothelial cells is thought to be a promising target for therapy in various cardiovascular diseases. Uncoupling protein 2 (UCP2) is a regulator of mitochondrial ROS generation and can antagonise oxidative stress-induced endothelial dysfunction. Several studies have revealed the important role of UCP2 in hyperglycaemia-induced modifications of mitochondrial function in endothelial cells. Additionally, potassium fluxes through the inner mitochondrial membrane, which are involved in ROS synthesis, affect the mitochondrial volume and change both the mitochondrial membrane potential and the transport of calcium into the mitochondria. In this review, we concentrate on the mitochondrial role in the cytoprotection phenomena of endothelial cells.
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Affiliation(s)
- Adam Szewczyk
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Warszawa, Poland
| | | | - Agnieszka Koziel
- Department of Bioenergetics, Adam Mickiewicz University, Poznań, Poland
| | - Izabela Sobieraj
- Department of Bioenergetics, Adam Mickiewicz University, Poznań, Poland
| | - Wioletta Nobik
- Department of Bioenergetics, Adam Mickiewicz University, Poznań, Poland
| | - Agnieszka Lukasiak
- Department of Biophysics, Warsaw University of Life Sciences-SGGW, Warszawa, Poland
| | - Agata Skup
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Warszawa, Poland
| | - Piotr Bednarczyk
- Department of Biophysics, Warsaw University of Life Sciences-SGGW, Warszawa, Poland
| | - Beata Drabarek
- Laboratory of Cellular Metabolism, Nencki Institute of Experimental Biology, Warszawa, Poland
| | - Dorota Dymkowska
- Laboratory of Cellular Metabolism, Nencki Institute of Experimental Biology, Warszawa, Poland
| | - Antoni Wrzosek
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Warszawa, Poland.
| | - Krzysztof Zablocki
- Laboratory of Cellular Metabolism, Nencki Institute of Experimental Biology, Warszawa, Poland
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Gai XY, Wei YH, Zhang W, Wuren TN, Wang YP, Li ZQ, Liu S, Ma L, Lu DX, Zhou Y, Ge RL. Echinacoside induces rat pulmonary artery vasorelaxation by opening the NO-cGMP-PKG-BKCa channels and reducing intracellular Ca2+ levels. Acta Pharmacol Sin 2015; 36:587-96. [PMID: 25864652 DOI: 10.1038/aps.2014.126] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Accepted: 10/14/2014] [Indexed: 01/18/2023] Open
Abstract
AIM Sustained pulmonary vasoconstriction as experienced at high altitude can lead to pulmonary hypertension (PH). The main purpose of this study is to investigate the vasorelaxant effect of echinacoside (ECH), a phenylethanoid glycoside from the Tibetan herb Lagotis brevituba Maxim and Cistanche tubulosa, on the pulmonary artery and its potential mechanism. METHODS Pulmonary arterial rings obtained from male Wistar rats were suspended in organ chambers filled with Krebs-Henseleit solution, and isometric tension was measured using a force transducer. Intracellular Ca(2+) levels were measured in cultured rat pulmonary arterial smooth muscle cells (PASMCs) using Fluo 4-AM. RESULTS ECH (30-300 μmol/L) relaxed rat pulmonary arteries precontracted by noradrenaline (NE) in a concentration-dependent manner, and this effect could be observed in both intact endothelium and endothelium-denuded rings, but with a significantly lower maximum response and a higher EC50 in endothelium-denuded rings. This effect was significantly blocked by L-NAME, TEA, and BaCl2. However, IMT, 4-AP, and Gli did not inhibit ECH-induced relaxation. Under extracellular Ca(2+)-free conditions, the maximum contraction was reduced to 24.54%±2.97% and 10.60%±2.07% in rings treated with 100 and 300 μmol/L of ECH, respectively. Under extracellular calcium influx conditions, the maximum contraction was reduced to 112.42%±7.30%, 100.29%±8.66%, and 74.74%±4.95% in rings treated with 30, 100, and 300 μmol/L of ECH, respectively. After cells were loaded with Fluo 4-AM, the mean fluorescence intensity was lower in cells treated with ECH (100 μmol/L) than with NE. CONCLUSION ECH suppresses NE-induced contraction of rat pulmonary artery via reducing intracellular Ca(2+) levels, and induces its relaxation through the NO-cGMP pathway and opening of K(+) channels (BKCa and KIR).
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Nunes KZ, Nunes DO, Silveira EA, Cruz Pereira CA, Broseghini Filho GB, Vassallo DV, Fioresi M. Chronic lead exposure decreases the vascular reactivity of rat aortas: the role of hydrogen peroxide. PLoS One 2015; 10:e0120965. [PMID: 25807237 PMCID: PMC4373949 DOI: 10.1371/journal.pone.0120965] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Accepted: 01/27/2015] [Indexed: 01/04/2023] Open
Abstract
We investigated whether exposure to small concentrations of lead alters blood pressure and vascular reactivity. Male Wistar rats were sorted randomly into the following two groups: control (Ct) and treatment with 100 ppm of lead (Pb), which was added to drinking water, for 30 days. Systolic blood pressure (BP) was measured weekly. Following treatment, aortic ring vascular reactivity was assessed. Tissue samples were properly stored for further biochemical investigation. The lead concentration in the blood reached approximately 8 μg/dL. Treatment increased blood pressure and decreased the contractile responses of the aortic rings to phenylephrine (1 nM–100 mM). Following N-nitro-L arginine methyl ester (L-NAME) administration, contractile responses increased in both groups but did not differ significantly between them. Lead effects on Rmax were decreased compared to control subjects following superoxide dismutase (SOD) administration. Catalase, diethyldithiocarbamic acid (DETCA), and apocynin increased the vasoconstrictor response induced by phenylephrine in the aortas of lead-treated rats but did not increase the vasoconstrictor response in the aortas of untreated rats. Tetraethylammonium (TEA) potentiated the vasoconstrictor response induced by phenylephrine in aortic segments in both groups, but these effects were greater in lead-treated rats. The co-incubation of TEA and catalase abolished the vasodilatory effect noted in the lead group. The present study is the first to demonstrate that blood lead concentrations well below the values established by international legislation increased blood pressure and decreased phenylephrine-induced vascular reactivity. The latter effect was associated with oxidative stress, specifically oxidative stress induced via increases in hydrogen peroxide levels and the subsequent effects of hydrogen peroxide on potassium channels.
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Affiliation(s)
- Karolini Zuqui Nunes
- Department of Physiological Sciences, Federal University of Espírito Santo, Vitória, ES, Brazil
- * E-mail:
| | - Dieli Oliveira Nunes
- Department of Physiological Sciences, Federal University of Espírito Santo, Vitória, ES, Brazil
| | - Edna Aparecida Silveira
- Department of Physiological Sciences, Federal University of Espírito Santo, Vitória, ES, Brazil
| | | | | | - Dalton Valentim Vassallo
- Department of Physiological Sciences, Federal University of Espírito Santo, Vitória, ES, Brazil
- Health Science Centre of Vitória—EMESCAM, Vitória, Espírito Santo, Brazil
| | - Mirian Fioresi
- Department of Physiological Sciences, Federal University of Espírito Santo, Vitória, ES, Brazil
- Department of Nursing, Federal University of Espírito Santo, Vitória, ES, Brazil
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110
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Altmann JB, Yan G, Meeks JF, Abood ME, Brailoiu E, Brailoiu GC. G protein-coupled estrogen receptor-mediated effects on cytosolic calcium and nanomechanics in brain microvascular endothelial cells. J Neurochem 2015; 133:629-39. [PMID: 25703621 DOI: 10.1111/jnc.13066] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 01/28/2015] [Accepted: 02/04/2015] [Indexed: 01/14/2023]
Abstract
G protein-coupled estrogen receptor (GPER) is a relatively recently identified non-nuclear estrogen receptor, expressed in several tissues, including brain and blood vessels. The mechanisms elicited by GPER activation in brain microvascular endothelial cells are incompletely understood. The purpose of this work was to assess the effects of GPER activation on cytosolic Ca(2+) concentration, [Ca(2+)](i), nitric oxide production, membrane potential and cell nanomechanics in rat brain microvascular endothelial cells (RBMVEC). Extracellular but not intracellular administration of G-1, a selective GPER agonist, or extracellular administration of 17-β-estradiol and tamoxifen, increased [Ca(2+)](i) in RBMVEC. The effect of G-1 on [Ca(2+)](i) was abolished in Ca(2+) -free saline or in the presence of a L-type Ca(2+) channel blocker. G-1 increased nitric oxide production in RBMVEC; the effect was prevented by NG-nitro-l-arginine methyl ester. G-1 elicited membrane hyperpolarization that was abolished by the antagonists of small and intermediate-conductance Ca(2+) -activated K(+) channels, apamin, and charibdotoxin. GPER-mediated responses were sensitive to G-36, a GPER antagonist. In addition, atomic force microscopy studies revealed that G-1 increased the modulus of elasticity, indicative of cytoskeletal changes and increase in RBMVEC stiffness. Our results unravel the mechanisms underlying GPER-mediated effects in RBMVEC with implications for the effect of estrogen on cerebral microvasculature. Activation of the G protein-coupled estrogen receptor (GPER) in rat brain microvascular endothelial cells (RBMVEC) increases [Ca(2+)](i) by promoting Ca(2+) influx. The increase in [Ca(2+)](i) leads to membrane hyperpolarization, nitric oxide (NO) production, and to cytoskeletal changes and increased cell stiffness. Our results unravel the mechanisms underlying GPER-mediated effects in RBMVEC with implications for the effect of estrogen on cerebral microvasculature.
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Affiliation(s)
- Joseph B Altmann
- Department of Pharmaceutical Sciences, Thomas Jefferson University, Jefferson School of Pharmacy, Philadelphia, Pennsylvania, USA
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111
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Dominguez Rieg JA, Burt JM, Ruth P, Rieg T. P2Y₂ receptor activation decreases blood pressure via intermediate conductance potassium channels and connexin 37. Acta Physiol (Oxf) 2015; 213:628-41. [PMID: 25545736 PMCID: PMC4442688 DOI: 10.1111/apha.12446] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Revised: 10/14/2014] [Accepted: 12/17/2014] [Indexed: 02/06/2023]
Abstract
AIMS Nucleotides are important paracrine regulators of vascular tone. We previously demonstrated that activation of P2Y₂ receptors causes an acute, NO-independent decrease in blood pressure, indicating this signalling pathway requires an endothelial-derived hyperpolarization (EDH) response. To define the mechanisms by which activation of P2Y₂ receptors initiates EDH and vasodilation, we studied intermediate-conductance (KCa3.1, expressed in endothelial cells) and big-conductance potassium channels (KCa1.1, expressed in smooth muscle cells) as well as components of the myoendothelial gap junction, connexins 37 and 40 (Cx37, Cx40), all hypothesized to be part of the EDH response. METHODS We compared the effects of a P2Y₂/₄ receptor agonist in wild-type (WT) mice and in mice lacking KCa3.1, KCa1.1, Cx37 or Cx40 under anaesthesia, while monitoring intra-arterial blood pressure and heart rate. RESULTS Acute activation of P2Y₂/₄ receptors (0.01-3 mg kg(-1) body weight i.v.) caused a biphasic blood pressure response characterized by a dose-dependent and rapid decrease in blood pressure in WT (maximal response % of baseline at 3 mg kg(-1) : -38 ± 1%) followed by a consecutive increase in blood pressure (+44 ± 11%). The maximal responses in KCa3.1(-/-) and Cx37(-/-) were impaired (-13 ± 5, +17 ± 7 and -27 ± 1, +13 ± 3% respectively), whereas the maximal blood pressure decrease in response to acetylcholine at 3 μg kg(-1) was not significantly different (WT: -53 ± 3%; KCa3.1(-/-) : -52 ± 3; Cx37(-/-) : -53 ± 3%). KCa1.1(-/-) and Cx40(-/-) showed an identical biphasic response to P2Y2/4 receptor activation compared to WT. CONCLUSIONS The data suggest that the P2Y2/4 receptor activation elicits blood pressure responses via distinct mechanisms involving KCa3.1 and Cx37.
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MESH Headings
- Animals
- Blood Pressure/drug effects
- Connexins/deficiency
- Connexins/genetics
- Connexins/metabolism
- Dose-Response Relationship, Drug
- Endothelial Cells/drug effects
- Endothelial Cells/metabolism
- Heart Rate/drug effects
- Inosine/analogs & derivatives
- Inosine/pharmacology
- Intermediate-Conductance Calcium-Activated Potassium Channels/deficiency
- Intermediate-Conductance Calcium-Activated Potassium Channels/genetics
- Intermediate-Conductance Calcium-Activated Potassium Channels/metabolism
- Large-Conductance Calcium-Activated Potassium Channel alpha Subunits/genetics
- Large-Conductance Calcium-Activated Potassium Channel alpha Subunits/metabolism
- Male
- Mice, 129 Strain
- Mice, Inbred C57BL
- Mice, Knockout
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Myocytes, Smooth Muscle/drug effects
- Myocytes, Smooth Muscle/metabolism
- Nitric Oxide Synthase Type III/genetics
- Nitric Oxide Synthase Type III/metabolism
- Purinergic P2Y Receptor Agonists
- Receptors, Purinergic P2Y2/drug effects
- Receptors, Purinergic P2Y2/metabolism
- Signal Transduction/drug effects
- Uridine Triphosphate/analogs & derivatives
- Uridine Triphosphate/pharmacology
- Vasodilation/drug effects
- Gap Junction alpha-4 Protein
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Affiliation(s)
- J. A. Dominguez Rieg
- Department of Basic Sciences, Bastyr University California, San Diego, CA, USA
- VA San Diego Healthcare System, San Diego, CA, USA
| | - J. M. Burt
- Department of Physiology, University of Arizona, Tucson, AZ, USA
| | - P. Ruth
- Department of Pharmacology, Toxicology and Clinical Pharmacy, University of Tübingen, Tübingen, Germany
| | - T. Rieg
- VA San Diego Healthcare System, San Diego, CA, USA
- Division of Nephrology-Hypertension, Department of Medicine, University of California San Diego, La Jolla, CA, USA
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112
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Yi F, Ling TY, Lu T, Wang XL, Li J, Claycomb WC, Shen WK, Lee HC. Down-regulation of the small conductance calcium-activated potassium channels in diabetic mouse atria. J Biol Chem 2015; 290:7016-26. [PMID: 25605734 DOI: 10.1074/jbc.m114.607952] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The small conductance Ca(2+)-activated K(+) (SK) channels have recently been found to be expressed in the heart, and genome-wide association studies have shown that they are implicated in atrial fibrillation. Diabetes mellitus is an independent risk factor of atrial fibrillation, but the ionic mechanism underlying this relationship remains unclear. We hypothesized that SK channel function is abnormal in diabetes mellitus, leading to altered cardiac electrophysiology. We found that in streptozotocin-induced diabetic mice, the expression of SK2 and SK3 isoforms was down-regulated by 85 and 92%, respectively, whereas that of SK1 was not changed. SK currents from isolated diabetic mouse atrial myocytes were significantly reduced compared with controls. The resting potentials of isolated atrial preparations were similar between control and diabetic mice, but action potential durations were significantly prolonged in the diabetic atria. Exposure to apamin significantly prolonged action potential durations in control but not in diabetic atria. Production of reactive oxygen species was significantly increased in diabetic atria and in high glucose-cultured HL-1 cells, whereas exposure of HL-1 cells in normal glucose culture to H2O2 reduced the expression of SK2 and SK3. Tyrosine nitration in SK2 and SK3 was significantly increased by high glucose culture, leading to accelerated channel turnover. Treatment with Tiron prevented these changes. Our results suggest that increased oxidative stress in diabetes results in SK channel-associated electrical remodeling in diabetic atria and may promote arrhythmogenesis.
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Affiliation(s)
- Fu Yi
- From the Department of Internal Medicine, Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota 55905, Department of Cardiovascular Diseases, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China
| | - Tian-You Ling
- From the Department of Internal Medicine, Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota 55905, Department of Cardiology, Ruijin Hospital, Shanghai JiaoTong University School of Medicine, Shanghai 200025, China
| | - Tong Lu
- From the Department of Internal Medicine, Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota 55905
| | - Xiao-Li Wang
- From the Department of Internal Medicine, Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota 55905
| | - Jingchao Li
- From the Department of Internal Medicine, Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota 55905, Department of Emergency Medicine, Henan Provincial People's Hospital, Affiliated Hospital of Zhengzhou University, Zhengzhou 450003, Henan, China
| | - William C Claycomb
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, New Orleans, Louisiana 70112, and
| | - Win-Kuang Shen
- Department of Internal Medicine, Division of Cardiovascular Diseases, Mayo Clinic, Phoenix, Arizona 85255
| | - Hon-Chi Lee
- From the Department of Internal Medicine, Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota 55905,
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113
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Wierzbowska J, Wojtkiewicz S, Zbieć A, Wierzbowski R, Liebert A, Maniewski R. Prolonged postocclusive hyperemia response in patients with normal-tension glaucoma. Med Sci Monit 2014; 20:2607-16. [PMID: 25502623 PMCID: PMC4266367 DOI: 10.12659/msm.891069] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Background It is believed that endothelial dysfunction may be a link between systemic and ocular dysregulation in glaucoma. The aim of this study was to evaluate peripheral vascular reactive hyperemia in response to occlusion test and to correlate peripheral vascular findings with retrobulbar hemodynamics parameters in patients with normal-tension glaucoma. Material/Methods Forty-eight patients with normal-tension glaucoma (mean age 58.1 years, 38 women) and 40 control subjects (mean age 54.1 years, 36 women) were subjected to a brachial arterial occlusion test and color Doppler imaging (LOGIQ 9, GE Medical Systems) of the retrobulbar arteries. Finger hyperemia was assessed by using a 2-channel laser Doppler flowmeter (MBF-3D, Moor Instruments, Ltd.). Time parameters (time to peak flow, half-time of hyperemia, time of recovery) and amplitude parameters (maximum hyperemia response, biological zero) of the post-occlusive reactive hyperemia signal pattern as well as velocities and resistance index of the ophthalmic, central retinal, and short posterior ciliary arteries were evaluated and compared between study groups. Results In glaucoma patients, time to peak flow and half-time of hyperemia were significantly longer (21.4 vs. 12.0 s, p=0.02 and 74.1 vs. 44.2 s, p=0.03, respectively) and biological zero was significantly lower (2.4 vs. 3.2, p=0.01) comparing with healthy subjects. In glaucoma patients, peak-systolic and end-diastolic velocities of central retinal artery were significantly lower (12.8 vs.14.1, p=0.03 and 3.9 vs. 4.7, p=0.01, respectively) and resistance index of this artery was significantly higher (0.69 vs. 0.67, p=0.03) compared to controls. In the glaucoma group, maximum hyperemic response was negatively correlated with the resistance index of temporal short posterior ciliary arteries (r=−0.4, p=0.01), whereas in the control group half-time of hyperemia was negatively correlated with end-diastolic velocity of the central retinal artery (r=−0.3, p=0.03). Conclusions Arterial occlusion test elicited a prolonged systemic hyperemia response in patients with glaucoma as compared with healthy subjects. Retrobulbar blood flow alterations in glaucoma patients may be related to systemic vascular dysregulation.
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Affiliation(s)
- Joanna Wierzbowska
- Department of Ophthalmology, Military Institute of Medicine, Warsaw, Poland
| | - Stanisław Wojtkiewicz
- Nałęcz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland
| | - Anna Zbieć
- Nałęcz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland
| | - Robert Wierzbowski
- Department of Cardiology, Military Institute of Medicine, Warsaw, Poland
| | - Adam Liebert
- Nałęcz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland
| | - Roman Maniewski
- Nałęcz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland
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114
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Bentzen BH, Olesen SP, Rønn LCB, Grunnet M. BK channel activators and their therapeutic perspectives. Front Physiol 2014; 5:389. [PMID: 25346695 PMCID: PMC4191079 DOI: 10.3389/fphys.2014.00389] [Citation(s) in RCA: 113] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Accepted: 09/19/2014] [Indexed: 01/05/2023] Open
Abstract
The large conductance calcium- and voltage-activated K+ channel (KCa1.1, BK, MaxiK) is ubiquitously expressed in the body, and holds the ability to integrate changes in intracellular calcium and membrane potential. This makes the BK channel an important negative feedback system linking increases in intracellular calcium to outward hyperpolarizing potassium currents. Consequently, the channel has many important physiological roles including regulation of smooth muscle tone, neurotransmitter release and neuronal excitability. Additionally, cardioprotective roles have been revealed in recent years. After a short introduction to the structure, function and regulation of BK channels, we review the small organic molecules activating BK channels and how these tool compounds have helped delineate the roles of BK channels in health and disease.
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Affiliation(s)
- Bo H Bentzen
- Department of Biomedical Sciences, Faculty of Health Sciences, Danish Arrhythmia Research Centre, University of Copenhagen Copenhagen, Denmark ; Acesion Pharma Copenhagen, Denmark
| | - Søren-Peter Olesen
- Department of Biomedical Sciences, Faculty of Health Sciences, Danish Arrhythmia Research Centre, University of Copenhagen Copenhagen, Denmark
| | | | - Morten Grunnet
- Acesion Pharma Copenhagen, Denmark ; H. Lundbeck A/S Copenhagen, Denmark
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115
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Tano JY, Gollasch M. Calcium-activated potassium channels in ischemia reperfusion: a brief update. Front Physiol 2014; 5:381. [PMID: 25339909 PMCID: PMC4186282 DOI: 10.3389/fphys.2014.00381] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Accepted: 09/13/2014] [Indexed: 12/24/2022] Open
Abstract
Ischemia and reperfusion (IR) injury constitutes one of the major causes of cardiovascular morbidity and mortality. The discovery of new therapies to block/mediate the effects of IR is therefore an important goal in the biomedical sciences. Dysfunction associated with IR involves modification of calcium-activated potassium channels (KCa) through different mechanisms, which are still under study. Respectively, the KCa family, major contributors to plasma membrane calcium influx in cells and essential players in the regulation of the vascular tone are interesting candidates. This family is divided into two groups including the large conductance (BKCa) and the small/intermediate conductance (SKCa/IKCa) K(+) channels. In the heart and brain, these channels have been described to offer protection against IR injury. BKCa and SKCa channels deserve special attention since new data demonstrate that these channels are also expressed in mitochondria. More studies are however needed to fully determine their potential use as therapeutic targets.
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Affiliation(s)
- Jean-Yves Tano
- Experimental and Clinical Research Center, Charité University Medicine - Max Delbrück Center (MDC) for Molecular Medicine Berlin, Germany ; Nephrology/Intensive Care Section, Charité University Medicine Berlin, Germany
| | - Maik Gollasch
- Experimental and Clinical Research Center, Charité University Medicine - Max Delbrück Center (MDC) for Molecular Medicine Berlin, Germany ; Nephrology/Intensive Care Section, Charité University Medicine Berlin, Germany
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116
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Machado NT, Maciel PM, Alustau MC, Queiroz TM, Furtado FF, Assis VL, Veras RC, Araújo IG, Athayde-Filho PF, Medeiros IA. Nitric oxide as a target for the hypotensive and vasorelaxing effects induced by (Z)-ethyl 12-nitrooxy-octadec-9-enoate in rats. Eur J Pharm Sci 2014; 62:317-25. [DOI: 10.1016/j.ejps.2014.06.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Revised: 04/16/2014] [Accepted: 06/13/2014] [Indexed: 10/25/2022]
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117
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Abstract
There is an urgent need to identify novel interventions for mitigating the progression of diabetic nephropathy. Diabetic nephropathy is characterized by progressive renal fibrosis, in which tubulointerstitial fibrosis has been shown to be the final common pathway of all forms of chronic progressive renal disease, including diabetic nephropathy. Therefore targeting the possible mechanisms that drive this process may provide novel therapeutics which allow the prevention and potentially retardation of the functional decline in diabetic nephropathy. Recently, the Ca2+-activated K+ channel KCa3.1 (KCa3.1) has been suggested as a potential therapeutic target for nephropathy, based on its ability to regulate Ca2+ entry into cells and modulate Ca2+-signalling processes. In the present review, we focus on the physiological role of KCa3.1 in those cells involved in the tubulointerstitial fibrosis, including proximal tubular cells, fibroblasts, inflammatory cells (T-cells and macrophages) and endothelial cells. Collectively these studies support further investigation into KCa3.1 as a therapeutic target in diabetic nephropathy.
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118
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Ginsenoside Re enhances small-conductance Ca(2+)-activated K(+) current in human coronary artery endothelial cells. Life Sci 2014; 115:15-21. [PMID: 25242515 DOI: 10.1016/j.lfs.2014.09.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2014] [Revised: 08/23/2014] [Accepted: 09/09/2014] [Indexed: 01/26/2023]
Abstract
AIMS Ginsenosides, active components in ginseng, have been shown to increase nitric oxide (NO) production in aortic endothelial cells. This effect was reversed by tetraethylammonium (TEA) inhibition of endothelial Ca(2+)-activated K(+) (KCa) channels. The objectives of this study, therefore, were to test 1) whether vasorelaxing ginsenoside Re could affect KCa current, an important regulator of NO production, in human coronary artery endothelial cells (HCAECs); and 2) whether small-conductance KCa (SKCa) channel was the channel subtype involved. MAIN METHODS Ionic currents of cultured HCAECs were studied using whole-cell patch clamp technique. KEY FINDINGS Ginsenoside Re dose-dependently increased endothelial outward currents, with an EC50 of 408.90±1.59nM, and a maximum increase of 36.20±5.62% (mean±SEM; p<0.05). Apamin, an SKCa channel inhibitor, could block this effect, while La(3+), a nonselective cation channel (NSC) blocker, could not. When NSC channel, inward-rectifier K(+) channel, intermediate-, and large-conductance KCa channels were simultaneously blocked, ginsenoside Re could still increase outward currents significantly (35.49±4.22%; p<0.05); this effect was again abolished by apamin. Repeating the experiments when Cl(-) channel was additionally blocked gave similar results. Finally, we demonstrated that ginsenoside Re could hyperpolarize HCAECs; this effect was reversed by apamin. These data clearly indicate that ginsenoside Re increased HCAEC outward current via SKCa channel activation, and NSC channel was not involved. SIGNIFICANCE This is the first report to demonstrate that ginsenoside Re could increase SKCa channel activity in HCAECs. This can be a mechanism mediating ginseng's beneficial actions on coronary vessels.
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119
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Dias FMV, Ribeiro Júnior RF, Fernandes AA, Fiorim J, Travaglia TCF, Vassallo DV, Stefanon I. Na+K+-ATPase activity and K+ channels differently contribute to vascular relaxation in male and female rats. PLoS One 2014; 9:e106345. [PMID: 25187951 PMCID: PMC4154682 DOI: 10.1371/journal.pone.0106345] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Accepted: 08/07/2014] [Indexed: 11/19/2022] Open
Abstract
Gender associated differences in vascular reactivity regulation might contribute to the low incidence of cardiovascular disease in women. Cardiovascular protection is suggested to depend on female sex hormones' effects on endothelial function and vascular tone regulation. We tested the hypothesis that potassium (K+) channels and Na+K+-ATPase may be involved in the gender-based vascular reactivity differences. Aortic rings from female and male rats were used to examine the involvement of K+ channels and Na+K+-ATPase in vascular reactivity. Acetylcholine (ACh)-induced relaxation was analyzed in the presence of L-NAME (100 µM) and the following K+ channels blockers: tetraethylammonium (TEA, 2 mM), 4-aminopyridine (4-AP, 5 mM), iberiotoxin (IbTX, 30 nM), apamin (0.5 µM) and charybdotoxin (ChTX, 0.1 µM). The ACh-induced relaxation sensitivity was greater in the female group. After incubation with 4-AP the ACh-dependent relaxation was reduced in both groups. However, the dAUC was greater in males, suggesting that the voltage-dependent K+ channel (Kv) participates more in males. Inhibition of the three types of Ca2+-activated K+ channels induced a greater reduction in Rmax in females than in males. The functional activity of the Na+K+-ATPase was evaluated by KCl-induced relaxation after L-NAME and OUA incubation. OUA reduced K+-induced relaxation in female and male groups, however, it was greater in males, suggesting a greater Na+K+-ATPase functional activity. L-NAME reduced K+-induced relaxation only in the female group, suggesting that nitric oxide (NO) participates more in their functional Na+K+-ATPase activity. These results suggest that the K+ channels involved in the gender-based vascular relaxation differences are the large conductance Ca2+-activated K+ channels (BKCa) in females and Kv in males and in the K+-induced relaxation and the Na+K+-ATPase vascular functional activity is greater in males.
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Affiliation(s)
- Fernanda Moura Vargas Dias
- Universidade Federal do Espírito Santo, Departamento de Ciências Fisiológicas, Vitória, Espírito Santo, Brasil
| | | | - Aurélia Araújo Fernandes
- Universidade Federal do Espírito Santo, Departamento de Ciências Fisiológicas, Vitória, Espírito Santo, Brasil
| | - Jonaina Fiorim
- Universidade Federal do Espírito Santo, Departamento de Ciências Fisiológicas, Vitória, Espírito Santo, Brasil
| | | | - Dalton Valentim Vassallo
- Universidade Federal do Espírito Santo, Departamento de Ciências Fisiológicas, Vitória, Espírito Santo, Brasil
| | - Ivanita Stefanon
- Universidade Federal do Espírito Santo, Departamento de Ciências Fisiológicas, Vitória, Espírito Santo, Brasil
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NS1619-induced vasodilation is enhanced and differentially mediated in chronically hypoxic lungs. Lung 2014; 192:811-7. [PMID: 25104232 DOI: 10.1007/s00408-014-9633-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Accepted: 07/24/2014] [Indexed: 10/24/2022]
Abstract
PURPOSE To identify the effect of the benzimidazalone derivative, NS1619, on modulating pulmonary vascular tone in lungs from rats exposed to normoxia (21% FiO2) or chronic hypoxia (10% FiO2) for three weeks. METHODS Isolated perfused lungs were preconstricted (U46619), and dose-dependent vasodilation to NS1619 was assessed. To elucidate the mechanisms responsible, NS1619 vasodilatory responses were assessed following inhibition of large-conductance Ca(2+)-activated (BKCa; iberiotoxin and paxilline), L-type Ca2+ (nifedipine), K+ (tetraethylammonium), Cl- (niflumic acid), and cation/TRP (lanthanum) channels, as well as nitric oxide synthase (L-NAME). RESULTS Compared to normoxia, NS1619-induced vasodilation was significantly greater following hypoxia; however, NO-dependent vasodilation and BKCa-mediated vasodilation, in response to NS1619, were similar in the normoxic and hypoxic lungs. In contrast, direct activation of L-type Ca2+ and non-BKCa K+ channel was involved in the NS1619-induced vasodilation only in hypoxic lungs. CONCLUSIONS NS1619 causes pulmonary vasodilation by affecting multiple complementary pathways, including stimulation of NO production, activation of BKCa channels, other TEA-sensitive K+ channels, and L-type Ca2+ channels, and could be considered as a therapeutic agent in hypoxic PH.
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Byun EB, Sung NY, Yang MS, Song DS, Byun EH, Kim JK, Park JH, Song BS, Lee JW, Park SH, Byun MW, Kim JH. Procyanidin C1 causes vasorelaxation through activation of the endothelial NO/cGMP pathway in thoracic aortic rings. J Med Food 2014; 17:742-8. [PMID: 24971771 DOI: 10.1089/jmf.2013.2978] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The aim of this study was to clarify the efficacy of procyanidin C1 (Pro C1) for modulating vascular tone. Pro C1 induced a potent vasorelaxant effect on phenylephrine-constricted endothelium-intact thoracic aortic rings, but had no effect on denuded thoracic aortic rings. Moreover, Pro C1 caused a significant increase in nitric oxide (NO) production in endothelial cells. Pro C1-induced vasorelaxation and Pro C1-induced NO production were significantly decreased in the presence of a nonspecific potassium channel blocker (tetraethylammonium chloride [TEA]), an endothelial NO synthase inhibitor (N(G)-monomethyl-L-arginine [L-NMMA]), and a store-operated calcium entry inhibitor (2-aminoethyl diphenylborinate [2-APB]). Pro C1-induced vasorelaxation was also completely abolished by an inhibitor of soluble guanyl cyclase, which suggests that the Pro C1 effects observed involved cyclic guanosine monophosphate (cGMP) production. Interestingly, Pro C1 significantly enhanced basal cGMP levels. Taken together, these results indicate that Pro C1-induced vasorelaxation is associated with the activation of the calcium-dependent NO/cGMP pathway, involving potassium channel activation. Thus, Pro C1 may represent a novel and potentially therapeutically relevant compound for the treatment of cardiovascular diseases.
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Affiliation(s)
- Eui-Baek Byun
- 1 Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute , Jeongeup, Korea
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Abstract
The field of mitochondrial ion channels has recently seen substantial progress, including the molecular identification of some of the channels. An integrative approach using genetics, electrophysiology, pharmacology, and cell biology to clarify the roles of these channels has thus become possible. It is by now clear that many of these channels are important for energy supply by the mitochondria and have a major impact on the fate of the entire cell as well. The purpose of this review is to provide an up-to-date overview of the electrophysiological properties, molecular identity, and pathophysiological functions of the mitochondrial ion channels studied so far and to highlight possible therapeutic perspectives based on current information.
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Zhu R, Huang X, Hu XQ, Xiao D, Zhang L. Gestational hypoxia increases reactive oxygen species and inhibits steroid hormone-mediated upregulation of Ca(2+)-activated K(+) channel function in uterine arteries. Hypertension 2014; 64:415-22. [PMID: 24866137 DOI: 10.1161/hypertensionaha.114.03555] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Gestational hypoxia inhibits steroid hormone-induced upregulation of Ca(2+)-activated K(+) (KCa) channel activities in uterine arteries. We tested the hypothesis that increased reactive oxygen species play an important role in hypoxia-mediated inhibition of KCa channel activities. Uterine arteries were isolated from nonpregnant (nonpregnant uterine artery) and near-term (≈142-145 day) pregnant (pregnant uterine artery) sheep maintained at either sea level or high altitude (3820 m, Pao2: 60 mm Hg) for 110 days. In pregnant uterine arteries, hypoxia significantly decreased large conductance channel opener NS1619- and small conductance channel opener NS309-induced relaxations, which were partially restored by reactive oxygen species inhibitor N-acetylcysteine (NAC). NAC significantly increased large conductance KCa but not small conductance KCa current densities in uterine arterial smooth muscle cells in pregnant animals acclimatized to high altitude. The NAC-sensitive component of small conductance KCa-induced relaxations was diminished in endothelium-denuded arteries. In nonpregnant uterine arteries, NS1619- and NS309-induced relaxations were diminished compared with those in pregnant uterine arteries. Treatment of nonpregnant uterine arteries with 17β-estradiol and progesterone for 48 hours increased small conductance KCa type 3 protein abundance and NS1619- and NS309-induced relaxations, which were inhibited by hypoxia. This hypoxia-mediated inhibition was reversed by NAC. Consistently, steroid hormone treatment had no significant effects on large conductance KCa current density in nonpregnant uterine arteries of hypoxic animals in the absence of NAC but significantly increased it in the presence of NAC. These results suggest an important role of hypoxia-mediated reactive oxygen species in negatively regulating steroid hormone-mediated upregulation of KCa channel activity and adaptation of uterine vascular reactivity in pregnancy, which may contribute to the increased incidence of preeclampsia and fetal intrauterine growth restriction associated with gestational hypoxia.
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Affiliation(s)
- Ronghui Zhu
- From the Division of Pharmacology, Department of Basic Sciences, Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, CA
| | - Xiaohui Huang
- From the Division of Pharmacology, Department of Basic Sciences, Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, CA
| | - Xiang-Qun Hu
- From the Division of Pharmacology, Department of Basic Sciences, Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, CA
| | - DaLiao Xiao
- From the Division of Pharmacology, Department of Basic Sciences, Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, CA
| | - Lubo Zhang
- From the Division of Pharmacology, Department of Basic Sciences, Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, CA.
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Wandall-Frostholm C, Skaarup LM, Sadda V, Nielsen G, Hedegaard ER, Mogensen S, Köhler R, Simonsen U. Pulmonary hypertension in wild type mice and animals with genetic deficit in KCa2.3 and KCa3.1 channels. PLoS One 2014; 9:e97687. [PMID: 24858807 PMCID: PMC4032241 DOI: 10.1371/journal.pone.0097687] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Accepted: 04/22/2014] [Indexed: 11/18/2022] Open
Abstract
Objective In vascular biology, endothelial KCa2.3 and KCa3.1 channels contribute to arterial blood pressure regulation by producing membrane hyperpolarization and smooth muscle relaxation. The role of KCa2.3 and KCa3.1 channels in the pulmonary circulation is not fully established. Using mice with genetically encoded deficit of KCa2.3 and KCa3.1 channels, this study investigated the effect of loss of the channels in hypoxia-induced pulmonary hypertension. Approach and Result Male wild type and KCa3.1−/−/KCa2.3T/T(+DOX) mice were exposed to chronic hypoxia for four weeks to induce pulmonary hypertension. The degree of pulmonary hypertension was evaluated by right ventricular pressure and assessment of right ventricular hypertrophy. Segments of pulmonary arteries were mounted in a wire myograph for functional studies and morphometric studies were performed on lung sections. Chronic hypoxia induced pulmonary hypertension, right ventricular hypertrophy, increased lung weight, and increased hematocrit levels in either genotype. The KCa3.1−/−/KCa2.3T/T(+DOX) mice developed structural alterations in the heart with increased right ventricular wall thickness as well as in pulmonary vessels with increased lumen size in partially- and fully-muscularized vessels and decreased wall area, not seen in wild type mice. Exposure to chronic hypoxia up-regulated the gene expression of the KCa2.3 channel by twofold in wild type mice and increased by 2.5-fold the relaxation evoked by the KCa2.3 and KCa3.1 channel activator NS309, whereas the acetylcholine-induced relaxation - sensitive to the combination of KCa2.3 and KCa3.1 channel blockers, apamin and charybdotoxin - was reduced by 2.5-fold in chronic hypoxic mice of either genotype. Conclusion Despite the deficits of the KCa2.3 and KCa3.1 channels failed to change hypoxia-induced pulmonary hypertension, the up-regulation of KCa2.3-gene expression and increased NS309-induced relaxation in wild-type mice point to a novel mechanism to counteract pulmonary hypertension and to a potential therapeutic utility of KCa2.3/KCa3.1 activators for the treatment of pulmonary hypertension.
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Affiliation(s)
| | | | - Veeranjaneyulu Sadda
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
- Institute for Molecular Medicine, Cardiovascular and Renal Research, University of Southern Denmark, Odense, Denmark
| | - Gorm Nielsen
- Institute for Molecular Medicine, Cardiovascular and Renal Research, University of Southern Denmark, Odense, Denmark
| | | | - Susie Mogensen
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Ralf Köhler
- Institute for Molecular Medicine, Cardiovascular and Renal Research, University of Southern Denmark, Odense, Denmark
- Aragon Institute of Health Sciences I+CS and ARAID, Zaragoza, Spain
| | - Ulf Simonsen
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
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Berrout J, Mamenko M, Zaika OL, Chen L, Zang W, Pochynyuk O, O'Neil RG. Emerging role of the calcium-activated, small conductance, SK3 K+ channel in distal tubule function: regulation by TRPV4. PLoS One 2014; 9:e95149. [PMID: 24762817 PMCID: PMC3999037 DOI: 10.1371/journal.pone.0095149] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Accepted: 03/24/2014] [Indexed: 12/24/2022] Open
Abstract
The Ca2+-activated, maxi-K (BK) K+ channel, with low Ca2+-binding affinity, is expressed in the distal tubule of the nephron and contributes to flow-dependent K+ secretion. In the present study we demonstrate that the Ca2+-activated, SK3 (KCa2.3) K+ channel, with high Ca2+-binding affinity, is also expressed in the mouse kidney (RT-PCR, immunoblots). Immunohistochemical evaluations using tubule specific markers demonstrate significant expression of SK3 in the distal tubule and the entire collecting duct system, including the connecting tubule (CNT) and cortical collecting duct (CCD). In CNT and CCD, main sites for K+ secretion, the highest levels of expression were along the apical (luminal) cell membranes, including for both principal cells (PCs) and intercalated cells (ICs), posturing the channel for Ca2+-dependent K+ secretion. Fluorescent assessment of cell membrane potential in native, split-opened CCD, demonstrated that selective activation of the Ca2+-permeable TRPV4 channel, thereby inducing Ca2+ influx and elevating intracellular Ca2+ levels, activated both the SK3 channel and the BK channel leading to hyperpolarization of the cell membrane. The hyperpolarization response was decreased to a similar extent by either inhibition of SK3 channel with the selective SK antagonist, apamin, or by inhibition of the BK channel with the selective antagonist, iberiotoxin (IbTX). Addition of both inhibitors produced a further depolarization, indicating cooperative effects of the two channels on Vm. It is concluded that SK3 is functionally expressed in the distal nephron and collecting ducts where induction of TRPV4-mediated Ca2+ influx, leading to elevated intracellular Ca2+ levels, activates this high Ca2+-affinity K+ channel. Further, with sites of expression localized to the apical cell membrane, especially in the CNT and CCD, SK3 is poised to be a key pathway for Ca2+-dependent regulation of membrane potential and K+ secretion.
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Affiliation(s)
- Jonathan Berrout
- Department of Integrative Biology, The University of Texas Health Science Center Medical School, Houston, Texas, United States of America
| | - Mykola Mamenko
- Department of Integrative Biology, The University of Texas Health Science Center Medical School, Houston, Texas, United States of America
| | - Oleg L. Zaika
- Department of Integrative Biology, The University of Texas Health Science Center Medical School, Houston, Texas, United States of America
| | - Lihe Chen
- Department of Internal Medicine-Division of Renal Diseases and Hypertension, The University of Texas Health Science Center Medical School, Houston, Texas, United States of America
| | - Wenzheng Zang
- Department of Internal Medicine-Division of Renal Diseases and Hypertension, The University of Texas Health Science Center Medical School, Houston, Texas, United States of America
| | - Oleh Pochynyuk
- Department of Integrative Biology, The University of Texas Health Science Center Medical School, Houston, Texas, United States of America
| | - Roger G. O'Neil
- Department of Integrative Biology, The University of Texas Health Science Center Medical School, Houston, Texas, United States of America
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Mechanisms of endothelium-dependent relaxation evoked by anandamide in isolated human pulmonary arteries. Naunyn Schmiedebergs Arch Pharmacol 2014; 387:477-86. [PMID: 24682422 PMCID: PMC3984660 DOI: 10.1007/s00210-014-0961-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Accepted: 02/06/2014] [Indexed: 02/06/2023]
Abstract
Endocannabinoids contract, relax or do not affect vessels with different calibre and tone in the pulmonary circulation in four species. The aim of the present study was to determine the mechanisms involved in the anandamide-induced relaxation of human pulmonary arteries (hPAs). Studies were performed in the isolated hPAs pre-constricted with the prostanoid TP receptor agonist, U-46619. To detect fatty acid amide hydrolase (FAAH) expression, Western blots were used. Anandamide concentration dependently relaxed the endothelium-intact hPAs pre-constricted with U-46619. The anandamide-induced relaxation was virtually abolished by removal of the endothelium and strongly attenuated by inhibitors of cyclooxygenases (indomethacin, COX-1/COX-2, and nimesulide, COX-2), nitric oxide synthase (N (G) -nitro-L-arginine methyl ester) given separately or in combination, FAAH (URB597), and the prostanoid IP receptor antagonist, RO1138452. The anandamide-evoked relaxation in the endothelium-intact vessels was attenuated in KCl pre-constricted preparations or by the inhibitor of large-conductance Ca(2+)-activated K(+) channels, iberiotoxin. In experiments performed in the presence of URB597 to exclude effects of anandamide metabolites, the antagonist of the endothelial cannabinoid receptor, O-1918, diminished the anandamide-evoked relaxation whereas the antagonists of cannabinoid CB1, CB2 and vanilloid TRPV1 receptors, AM251, SR144528 and capsazepine, respectively, had no effect. Western blot studies revealed the occurrence of FAAH protein in the hPAs. The present study shows that anandamide breakdown products, cyclooxygenase pathways, nitric oxide, potassium channels and the O-1918-sensitive cannabinoid receptor play a role in the anandamide-induced relaxation of the hPAs with intact endothelium.
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Ellinsworth DC, Shukla N, Fleming I, Jeremy JY. Interactions between thromboxane A₂, thromboxane/prostaglandin (TP) receptors, and endothelium-derived hyperpolarization. Cardiovasc Res 2014; 102:9-16. [PMID: 24469536 DOI: 10.1093/cvr/cvu015] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Endothelium-dependent smooth muscle hyperpolarization (EDH) increasingly predominates over endothelium-derived nitric oxide (NO) as a participant in vasodilation as vessel size decreases. Its underlying nature is highly variable between vessel types, species, disease states, and exact experimental conditions, and is variably mediated by one or more transferable endothelium-derived hyperpolarizing factors and/or the electrotonic spread of endothelial hyperpolarization into the media via gap junctions. Although generally regarded (and studied) as a mechanism that is independent of NO and prostanoids, evidence has emerged that the endothelium-derived contracting factor and prostanoid thromboxane A2 can modulate several signalling components central to EDH, and therefore potentially curtail vasodilation through mechanisms that are distinct from those putatively involved in direct smooth muscle contraction. Notably, vascular production of thromboxane A2 is elevated in a number of cardiovascular disease states that promote endothelial dysfunction. This review will therefore discuss the mechanisms through which thromboxane A2 interacts with and modulates EDH, and will also consider the implications of such cross-talk in vasodilator control in health and disease.
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Affiliation(s)
- David C Ellinsworth
- Bristol Heart Institute, University of Bristol, Queens Building Level 7, Upper Maudlin St, Bristol Royal Infirmary, Upper Maudlin Street, Bristol BS2 8HW, UK
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Mitchell WK, Phillips BE, Williams JP, Rankin D, Smith K, Lund JN, Atherton PJ. Development of a new Sonovue™ contrast-enhanced ultrasound approach reveals temporal and age-related features of muscle microvascular responses to feeding. Physiol Rep 2013; 1:e00119. [PMID: 24303186 PMCID: PMC3841050 DOI: 10.1002/phy2.119] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Revised: 09/12/2013] [Accepted: 09/16/2013] [Indexed: 12/17/2022] Open
Abstract
Compromised limb blood flow in aging may contribute to the development of sarcopenia, frailty, and the metabolic syndrome. We developed a novel contrast-enhanced ultrasound technique using Sonovue™ to characterize muscle microvasculature responses to an oral feeding stimulus (15 g essential amino acids) in young (∼20 years) and older (∼70 years) men. Intensity-time replenishment curves were made via an ultrasound probe “fixed” over the quadriceps, with intermittent high mechanical index destruction of microbubbles within muscle vasculature. This permitted real-time measures of microvascular blood volume (MBV), microvascular flow velocity (MFV) and their product, microvascular blood flow (MBF). Leg blood flow (LBF) was measured by Doppler and insulin by enzyme-linked immunosorbent assay. Steady-state contrast concentrations needed for comparison between different physiological states were achieved <150 sec from commencing Sonovue™ infusion, and MFV and MBV measurements were completed <120 sec thereafter. Interindividual coefficients of variation in MBV and MFV were 35–40%, (N = 36). Younger men (N = 6) exhibited biphasic vascular responses to feeding with early increases in MBV (+36%, P < 0.008 45 min post feed) reflecting capillary recruitment, and late increases in MFV (+77%, P < 0.008) and MBF (+130%, P < 0.007 195 min post feed) reflecting more proximal vessel dilatation. Early MBV responses were synchronized with peak insulin but not increased LBF, while later changes in MFV and MBF occurred with insulin at post absorptive values but alongside increased LBF. All circulatory responses were absent in old men (N = 7). Thus, impaired postprandial circulation could impact age-related declines in muscle glucose disposal, protein anabolism, and muscle mass.
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Affiliation(s)
- William Kyle Mitchell
- Division of Clinical Metabolic and Molecular Physiology, School of Graduate Entry Medicine and Health, University of Nottingham Derby, U.K. ; Department of Surgery, Royal Derby Hospital Derby, U.K
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Contreras GF, Castillo K, Enrique N, Carrasquel-Ursulaez W, Castillo JP, Milesi V, Neely A, Alvarez O, Ferreira G, González C, Latorre R. A BK (Slo1) channel journey from molecule to physiology. Channels (Austin) 2013; 7:442-58. [PMID: 24025517 DOI: 10.4161/chan.26242] [Citation(s) in RCA: 121] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Calcium and voltage-activated potassium (BK) channels are key actors in cell physiology, both in neuronal and non-neuronal cells and tissues. Through negative feedback between intracellular Ca (2+) and membrane voltage, BK channels provide a damping mechanism for excitatory signals. Molecular modulation of these channels by alternative splicing, auxiliary subunits and post-translational modifications showed that these channels are subjected to many mechanisms that add diversity to the BK channel α subunit gene. This complexity of interactions modulates BK channel gating, modifying the energetic barrier of voltage sensor domain activation and channel opening. Regions for voltage as well as Ca (2+) sensitivity have been identified, and the crystal structure generated by the 2 RCK domains contained in the C-terminal of the channel has been described. The linkage of these channels to many intracellular metabolites and pathways, as well as their modulation by extracellular natural agents, has been found to be relevant in many physiological processes. This review includes the hallmarks of BK channel biophysics and its physiological impact on specific cells and tissues, highlighting its relationship with auxiliary subunit expression.
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Affiliation(s)
- Gustavo F Contreras
- Centro Interdisciplinario de Neurociencia de Valparaíso; Facultad de Ciencias; Universidad de Valparaíso; Valparaíso, Chile; Doctorado en Ciencias mención Neurociencia; Universidad de Valparaíso; Valparaíso, Chile
| | - Karen Castillo
- Centro Interdisciplinario de Neurociencia de Valparaíso; Facultad de Ciencias; Universidad de Valparaíso; Valparaíso, Chile
| | - Nicolás Enrique
- Grupo de Investigación en Fisiología Vascular (GINFIV); Universidad Nacional de la Plata; La Plata, Argentina
| | - Willy Carrasquel-Ursulaez
- Centro Interdisciplinario de Neurociencia de Valparaíso; Facultad de Ciencias; Universidad de Valparaíso; Valparaíso, Chile; Doctorado en Ciencias mención Neurociencia; Universidad de Valparaíso; Valparaíso, Chile
| | - Juan Pablo Castillo
- Centro Interdisciplinario de Neurociencia de Valparaíso; Facultad de Ciencias; Universidad de Valparaíso; Valparaíso, Chile; Facultad de Ciencias; Universidad de Chile; Santiago, Chile
| | - Verónica Milesi
- Grupo de Investigación en Fisiología Vascular (GINFIV); Universidad Nacional de la Plata; La Plata, Argentina
| | - Alan Neely
- Centro Interdisciplinario de Neurociencia de Valparaíso; Facultad de Ciencias; Universidad de Valparaíso; Valparaíso, Chile
| | | | - Gonzalo Ferreira
- Laboratorio de Canales Iónicos; Departamento de Biofísica; Facultad de Medicina; Universidad de la República; Montevideo, Uruguay
| | - Carlos González
- Centro Interdisciplinario de Neurociencia de Valparaíso; Facultad de Ciencias; Universidad de Valparaíso; Valparaíso, Chile
| | - Ramón Latorre
- Centro Interdisciplinario de Neurociencia de Valparaíso; Facultad de Ciencias; Universidad de Valparaíso; Valparaíso, Chile
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Wang TT, Zhou GH, Kho JH, Sun YY, Wen JF, Kang DG, Lee HS, Cho KW, Jin SN. Vasorelaxant action of an ethylacetate fraction of Euphorbia humifusa involves NO-cGMP pathway and potassium channels. JOURNAL OF ETHNOPHARMACOLOGY 2013; 148:655-663. [PMID: 23707330 DOI: 10.1016/j.jep.2013.05.025] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2012] [Revised: 04/15/2013] [Accepted: 05/15/2013] [Indexed: 06/02/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Euphorbia humifusa Willd. (EH) is an important traditional Chinese medicine that has commonly been used for treating bacillary dysentery and enteritis in many Asian countries for thousands of years. EH has a wide variety of pharmacological actions such as antioxidant, hypotensive, and hypolipidemic effects. However, the mechanisms involved are to be defined. AIM OF THE STUDY The present study was performed to evaluate the cardiovascular effects of EH in rats. MATERIALS AND METHODS Methanol extract of EH (MEH) and ethylacetate fraction of the MEH (EEH) was examined for their vascular relaxant effects in phenylephrine-precontracted aortic rings. Effects of EEH on systolic blood pressure and heart rate were tested in Sprague-Dawley rats. RESULTS MEH and EEH induced vasorelaxation in a concentration-dependent manner. Endothelium-denudation abolished the EEH-induced vasorelaxation. Pretreatment of the endothelium-intact aortic rings with N(G)-nitro-L-arginine methylester (L-NAME) and 1H-[1,2,4]-oxadiazolo-[4,3-α]-quinoxalin-1-one (ODQ) significantly inhibited the EEH-induced vasorelaxation. EEH increased cGMP levels of the aortic rings in a concentration-dependent manner and the effect was blocked by L-NAME or ODQ. Extracellular Ca(2+) depletion and treatments with thapsigargin, Gd(3+), and 2-aminoethyl diphenylborinate significantly attenuated the EEH-induced vasorelaxation. Wortmannin markedly attenuated the EEH-induced vasorelaxation. In addition, tetraethylammonium, iberiotoxin, and charybdotoxin, but not apamin, attenuated the EEH-induced vasorelaxation. Glibenclamide, indomethacin, atropine, and propranolol had no effects on the EEH-induced vasorelaxation. Furthermore, EEH decreased systolic blood pressure and heart rate in a concentration-dependent manner in rats. CONCLUSIONS The present study demonstrates that EEH induces endothelium-dependent vasorelaxation via eNOS-NO-cGMP signaling through the modification of intracellular Ca(2+), Ca(2+) entry, and large- and intermediate-conductance KCa channel homeostasis. The data also suggest that the Akt-eNOS pathway is involved in the EEH-induced vasorelaxation. EEH induces hypotension and bradycardia in vivo.
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Affiliation(s)
- Ting Ting Wang
- Institute of Materia Medica, Taishan Medical University, Middle of Changcheng Road, Taian, Shandong 271016, China
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Behringer EJ, Shaw RL, Westcott EB, Socha MJ, Segal SS. Aging impairs electrical conduction along endothelium of resistance arteries through enhanced Ca2+-activated K+ channel activation. Arterioscler Thromb Vasc Biol 2013; 33:1892-901. [PMID: 23723370 DOI: 10.1161/atvbaha.113.301514] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
OBJECTIVE Intercellular conduction of electrical signals underlies spreading vasodilation of resistance arteries. Small- and intermediate-conductance Ca(2+)-activated K(+) channels of endothelial cells serve a dual function by initiating hyperpolarization and modulating electrical conduction. We tested the hypothesis that regulation of electrical signaling by small- and intermediate-conductance Ca(2+)-activated K(+) channels is altered with advancing age. APPROACH AND RESULTS Intact endothelial tubes (60 µm wide; 1-3 mm long) were freshly isolated from male C57BL/6 mouse (Young: 4-6 months; Intermediate: 12-14 months; Old: 24-26 months) superior epigastric arteries. Using dual intracellular microelectrodes, current was injected (± 0.1-3 nA) at site 1 while recording membrane potential (Vm) at site 2 (separation distance: 50-2000 µm). Across age groups, greatest differences were observed between Young and Old. Resting Vm in Old (-38 ± 1 mV) was more negative (P<0.05) than Young (-30 ± 1 mV). Maximal hyperpolarization to both direct (NS309) and indirect (acetylcholine) activation of small- and intermediate-conductance Ca(2+)-activated K(+) channels was sustained (ΔVm ≈-40 mV) with age. The length constant (λ) for electrical conduction was reduced (P<0.05) from 1630 ± 80 µm (Young) to 1320 ± 80 µm (Old). Inhibiting small- and intermediate-conductance Ca(2+)-activated K(+) channels with apamin+charybdotoxin or scavenging hydrogen peroxide (H2O2) with catalase improved electrical conduction (P<0.05) in Old. Exogenous H2O2 (200 µmol/L) in Young evoked hyperpolarization and impaired electrical conduction; these effects were blocked by apamin+charybdotoxin. CONCLUSIONS Enhanced current loss through Ca2+-activated K+ channel activation impairs electrical conduction along the endothelium of resistance arteries with aging. Attenuating the spatial domain of electrical signaling will restrict the spread of vasodilation and thereby contribute to blood flow limitations associated with advanced age.
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Affiliation(s)
- Erik J Behringer
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO 65212, USA
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Zhu R, Hu XQ, Xiao D, Yang S, Wilson SM, Longo LD, Zhang L. Chronic hypoxia inhibits pregnancy-induced upregulation of SKCa channel expression and function in uterine arteries. Hypertension 2013; 62:367-74. [PMID: 23716582 DOI: 10.1161/hypertensionaha.113.01236] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Small-conductance Ca(2+)-activated K(+) (SKCa) channels are crucial in regulating vascular tone and blood pressure. The present study tested the hypothesis that SKCa channels play an important role in uterine vascular adaptation in pregnancy, which is inhibited by chronic hypoxia during gestation. Uterine arteries were isolated from nonpregnant and near-term pregnant sheep maintained at sea level (≈300 m) or exposed to high-altitude (3801 m) hypoxia for 110 days. Immunohistochemistry revealed the presence of SKCa channels type 2 (SK2) and type 3 (SK3) in both smooth muscles and endothelium of uterine arteries. The expression of SK2 and SK3 channels was significantly increased during pregnancy, which was inhibited by chronic hypoxia. In normoxic animals, both SKCa channel opener NS309 and a large-conductance (BKCa) channel opener NS1619 relaxed norepinephrine-contracted uterine arteries in pregnant but not nonpregnant sheep. These relaxations were inhibited by selective SKCa and BKCa channel blockers, respectively. NS309-induced relaxation was largely endothelium-independent. In high-altitude hypoxic animals, neither NS1691 nor NS309 produced significant relaxation of uterine arteries in either nonpregnant or pregnant sheep. Similarly, the role of SKCa channels in regulating the myogenic reactivity of uterine arteries in pregnant animals was abrogated by chronic hypoxia. Accordingly, the enhanced SKCa channel activity in uterine arterial myocytes of pregnant animals was ablated by chronic hypoxia. The findings suggest a novel mechanism of SKCa channels in regulating myogenic adaptation of uterine arteries in pregnancy and in the maladaptation of uteroplacental circulation caused by chronic hypoxia during gestation.
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Affiliation(s)
- Ronghui Zhu
- Center for Perinatal Biology, Department of Basic Sciences, Loma Linda University, School of Medicine, Loma Linda, CA 92350, USA
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Bednarczyk P, Koziel A, Jarmuszkiewicz W, Szewczyk A. Large-conductance Ca²⁺-activated potassium channel in mitochondria of endothelial EA.hy926 cells. Am J Physiol Heart Circ Physiol 2013; 304:H1415-27. [PMID: 23542921 DOI: 10.1152/ajpheart.00976.2012] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
In the present study, we describe the existence of a large-conductance Ca²⁺-activated potassium (BKCa) channel in the mitochondria of the human endothelial cell line EA.hy926. A single-channel current was recorded from endothelial mitoplasts (i.e., inner mitochondrial membrane) using the patch-clamp technique in the mitoplast-attached mode. A potassium-selective current was recorded with a mean conductance equal to 270 ± 10 pS in a symmetrical 150/150 mM KCl isotonic solution. The channel activity, which was determined as the open probability, increased with the addition of calcium ions and the potassium channel opener NS1619. Conversely, the activity of the channel was irreversibly blocked by paxilline and iberiotoxin, BKCa channel inhibitors. The open-state probability was found to be voltage dependent. The substances known to modulate BKCa channel activity influenced the bioenergetics of mitochondria isolated from human endothelial EA.hy926 cells. In isolated mitochondria, 100 μM Ca²⁺, 10 μM NS1619, and 0.5 μM NS11021 depolarized the mitochondrial membrane potential and stimulated nonphosphorylating respiration. These effects were blocked by iberiotoxin and paxilline in a potassium-dependent manner. Under phosphorylating conditions, NS1619-induced, iberiotoxin-sensitive uncoupling diverted energy from ATP synthesis during the phosphorylating respiration of the endothelial mitochondria. Immunological analysis with antibodies raised against proteins of the plasma membrane BKCa channel identified a pore-forming α-subunit and an auxiliary β₂-subunit of the channel in the endothelial mitochondrial inner membrane. In conclusion, we show for the first time that the inner mitochondrial membrane in human endothelial EA.hy926 cells contains a large-conductance calcium-dependent potassium channel with properties similar to those of the surface membrane BKCa channel.
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Affiliation(s)
- Piotr Bednarczyk
- Department of Biophysics, Warsaw University of Life Sciences, Warsaw, Poland
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134
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Yang H, Li X, Ma J, Lv X, Zhao S, Lang W, Zhang Y. Blockade of the intermediate-conductance Ca(2+)-activated K+ channel inhibits the angiogenesis induced by epidermal growth factor in the treatment of corneal alkali burn. Exp Eye Res 2013; 110:76-87. [PMID: 23482085 DOI: 10.1016/j.exer.2013.02.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2012] [Revised: 02/17/2013] [Accepted: 02/21/2013] [Indexed: 12/29/2022]
Abstract
Epidermal growth factor (EGF) is used to treat alkali-burned corneas. However, EGF-induced corneal angiogenesis, which is currently untreatable, is a side effect of this therapy. We therefore explored the role of the intermediate-conductance Ca(2+)-activated K(+) channel (KCa3.1) in EGF-induced angiogenesis and tested whether KCa3.1 blockade can suppress EGF-induced corneal angiogenesis. The proliferation, migration and tube formation of HUVECs (human umbilical vein endothelial cells) in response to EGF, the MEK inhibitor PD98059 and the KCa3.1 inhibitor TRAM-34 were analyzed in vitro via MTT, cell counting, scratch and tube formation assays. The protein and mRNA levels of KCa3.1, phosphorylated-ERK (P-ERK), total-ERK (T-ERK), cyclin-dependent kinase 4 (CDK4), vimentin and MMP-2 were assessed via western blotting and RT-PCR. KCa3.1 and vimentin expression were also detected through immunofluorescence staining. Flow cytometry was performed to examine the cell cycle. Further, an in vivo murine alkali-burned cornea model was developed and treated with EGF and TRAM-34 eye drops to analyze the effect of these treatments on corneal healing and angiogenesis. The corneas were also analyzed by histological staining. The in vitro results showed that EGF induces the upregulation of KCa3.1 and P-ERK in HUVECs and that this upregulation is suppressed by PD98059. EGF stimulates proliferation, migration and tube formation in HUVECs, and this effect can be suppressed by TRAM-34. TRAM-34 also arrests HUVECs in the G1 phase of the cell cycle and downregulates CDK4, vimentin and MMP-2 in these cells. The in vivo results indicated that TRAM-34 suppresses EGF-induced corneal angiogenesis without affecting EGF-induced corneal wound healing. In summary, the upregulation of KCa3.1 may be crucial for EGF-induced angiogenesis through the MAPK/ERK signaling pathway. Thus, KCa3.1 may be a potential target for the treatment of EGF-induced corneal angiogenesis.
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Affiliation(s)
- Huike Yang
- Department of Anatomy, Harbin Medical University, Harbin 150081, China
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135
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Itoh T, Maekawa T, Shibayama Y. Characteristics of ACh-induced hyperpolarization and relaxation in rabbit jugular vein. Br J Pharmacol 2013; 167:682-96. [PMID: 22595036 DOI: 10.1111/j.1476-5381.2012.02038.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND AND PURPOSE The roles played by endothelium-derived NO and prostacyclin and by endothelial cell hyperpolarization in ACh-induced relaxation have been well characterized in arteries. However, the mechanisms underlying ACh-induced relaxation in veins remain to be fully clarified. EXPERIMENTAL APPROACH ACh-induced smooth muscle cell (SMC) hyperpolarization and relaxation were measured in endothelium-intact and -denuded preparations of rabbit jugular vein. KEY RESULTS In endothelium-intact preparations, ACh (≤ 10⁻⁸ M) marginally increased the intracellular concentration of Ca²⁺ ([Ca²⁺](i)) in endothelial cells but did not alter the SMC membrane potential. However, ACh (10⁻¹⁰ -10⁻⁸ M) induced a concentration-dependent relaxation during the contraction induced by PGF(2α) and this relaxation was blocked by the NO synthase inhibitor N(ω) -nitro-l-arginine. ACh (10⁻⁸ -10⁻⁶ M) concentration-dependently increased endothelial [Ca²⁺](i) and induced SMC hyperpolarization and relaxation. These SMC responses were blocked in the combined presence of apamin [blocker of small-conductance Ca²⁺-activated K⁺ (SK(Ca) , K(Ca) 2.3) channel], TRAM 34 [blocker of intermediate-conductance Ca²⁺ -activated K⁺ (IK(Ca) , K(Ca) 3.1) channel] and margatoxin [blocker of subfamily of voltage-gated K⁺ (K(V) ) channel, K(V) 1]. CONCLUSIONS AND IMPLICATIONS In rabbit jugular vein, NO plays a primary role in endothelium-dependent relaxation at very low concentrations of ACh (10⁻¹⁰ -10⁻⁸ M). At higher concentrations, ACh (10⁻⁸ -3 × 10⁻⁶ M) induces SMC hyperpolarization through activation of endothelial IK(Ca) , K(V) 1 and (possibly) SK(Ca) channels and produces relaxation. These results imply that ACh regulates rabbit jugular vein tonus through activation of two endothelium-dependent regulatory mechanisms.
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Affiliation(s)
- Takeo Itoh
- Department of Pharmacology, Graduate School of Medical Sciences, Nagoya City University, Japan.
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136
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Bondarenko A, Panasiuk O, Stepanenko L, Goswami N, Sagach V. Reduced hyperpolarization of endothelial cells following high dietary Na+: effects of enalapril and tempol. Clin Exp Pharmacol Physiol 2012; 39:608-13. [PMID: 22540516 DOI: 10.1111/j.1440-1681.2012.05718.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
1. High dietary Na(+) is associated with impaired vascular endothelial function. However, the underlying mechanisms are not completely understood. In the present study, we investigated whether the endothelial hyperpolarization response to acetylcholine (ACh) exhibited any abnormalities in Wistar rats fed a high-salt diet (HSD) for 1 month and, if so, whether chronic treatment with the angiotensin-converting enzyme inhibitor enalapril or the anti-oxidant tempol could normalize the response. Membrane potential was recorded using the perforated patch-clamp technique on the endothelium of rat aorta. 2. Acetylcholine (2 μmol/L) produced a hyperpolarization sensitive to TRAM-34, a blocker of intermediate-conductance Ca(2+) -sensitive K(+) channels (IK(Ca)), but not to apamin, a blocker of small-conductance Ca(2+)-sensitive K(+) channels (SK(Ca)). NS309 (3 μmol/L), an activator of SK(Ca) and IK(Ca) channels, produced a hyperpolarization of similar magnitude as ACh. 3. In the HSD group, the ACh-evoked hyperpolarization was significantly attenuated compared with that in the control group, which was fed normal chow rather than an HSD. Similarly, the hyperpolarization produced by NS309 was weaker in tissues from HSD-fed rats. 4. Combination of HSD with chronic enalapril treatment (20 mg/kg per day for 1 month) normalized endothelial hyperpolarizing responses to ACh. Chronic tempol treatment (1 mmol/L in tap water for 1 month) prevented the reduced hyperpolarization to ACh. 5. The results of the present study indicate that excess in dietary Na(+) results in a failure of endothelial cells to generate normal IK(Ca) channel-mediated hyperpolarizing responses. Our observations implicate oxidative stress mediated by increased angiotensin II signalling as a mechanism underlying altered endothelial hyperpolarization during dietary salt loading.
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Affiliation(s)
- Alexander Bondarenko
- Circulatory Physiology Department, AA Bogomoletz Institute of Physiology, Kiev, Ukraine.
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137
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Abstract
The present review first summarizes the complex chain of events, in endothelial and vascular smooth muscle cells, that leads to endothelium-dependent relaxations (vasodilatations) due to the generation of nitric oxide (NO) by endothelial nitric oxide synthase (eNOS) and how therapeutic interventions may improve the bioavailability of NO and thus prevent/cure endothelial dysfunction. Then, the role of other endothelium-derived mediators (endothelium-derived hyperpolarizing (EDHF) and contracting (EDCF) factors, endothelin-1) and signals (myoendothelial coupling) is summarized also, with special emphasis on their interaction(s) with the NO pathway, which make the latter not only a major mediator but also a key regulator of endothelium-dependent responses.
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138
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Mishra RC, Belke D, Wulff H, Braun AP. SKA-31, a novel activator of SK(Ca) and IK(Ca) channels, increases coronary flow in male and female rat hearts. Cardiovasc Res 2012; 97:339-48. [PMID: 23118129 DOI: 10.1093/cvr/cvs326] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
AIMS Endothelial SK(Ca) and IK(Ca) channels play an important role in the regulation of vascular function and systemic blood pressure. Based on our previous findings that small molecule activators of SK(Ca) and IK(Ca) channels (i.e. NS309 and SKA-31) can inhibit myogenic tone in isolated resistance arteries, we hypothesized that this class of compounds may induce effective vasodilation in an intact vascular bed, such as the coronary circulation. METHODS AND RESULTS In a Langendorff-perfused, beating rat heart preparation, acute bolus administrations of SKA-31 (0.01-5 µg) dose-dependently increased total coronary flow (25-30%) in both male and female hearts; these responses were associated with modest, secondary increases in left ventricular (LV) systolic pressure and heart rate. SKA-31 evoked responses in coronary flow, LV pressure, and heart rate were qualitatively comparable to acute responses evoked by bradykinin (1 µg) and adenosine (10 µg). In the presence of apamin and TRAM-34, selective blockers of SK(Ca) and IK(Ca) channels, respectively, SKA-31 and bradykinin-induced responses were largely inhibited, whereas the adenosine-induced changes were blocked by ∼40%; TRAM-34 alone produced less inhibition. Sodium nitroprusside (SNP, 0.2 μg bolus dose) evoked changes in coronary flow, LV pressure, and heart rate were similar to those induced by SKA-31, but were unaffected by apamin + TRAM-34. The NOS inhibitor L-NNA reduced bradykinin- and adenosine-evoked changes, but did not affect responses to either SKA-31 or SNP. CONCLUSION Our study demonstrates that SKA-31 can rapidly and reversibly induce dilation of the coronary circulation in intact functioning hearts under basal flow and contractility conditions.
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Affiliation(s)
- Ramesh C Mishra
- Department of Physiology and Pharmacology, Faculty of Medicine, University of Calgary, 3330 Hospital Dr. NW, Calgary, AB, Canada T2N 4N1
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139
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Hu XQ, Zhang L. Function and regulation of large conductance Ca(2+)-activated K+ channel in vascular smooth muscle cells. Drug Discov Today 2012; 17:974-87. [PMID: 22521666 PMCID: PMC3414640 DOI: 10.1016/j.drudis.2012.04.002] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2012] [Revised: 03/06/2012] [Accepted: 04/05/2012] [Indexed: 12/23/2022]
Abstract
Large conductance Ca(2+)-activated K(+) (BK(Ca)) channels are abundantly expressed in vascular smooth muscle cells. Activation of BK(Ca) channels leads to hyperpolarization of cell membrane, which in turn counteracts vasoconstriction. Therefore, BK(Ca) channels have an important role in regulation of vascular tone and blood pressure. The activity of BK(Ca) channels is subject to modulation by various factors. Furthermore, the function of BK(Ca) channels are altered in both physiological and pathophysiological conditions, such as pregnancy, hypertension and diabetes, which has dramatic impacts on vascular tone and hemodynamics. Consequently, compounds and genetic manipulation that alter activity and expression of the channel might be of therapeutic interest.
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Affiliation(s)
- Xiang-Qun Hu
- Center for Perinatal Biology, Division of Pharmacology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA.
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140
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Behringer EJ, Segal SS. Spreading the signal for vasodilatation: implications for skeletal muscle blood flow control and the effects of ageing. J Physiol 2012; 590:6277-84. [PMID: 22890708 DOI: 10.1113/jphysiol.2012.239673] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Blood flow control requires coordinated contraction and relaxation of smooth muscle cells (SMCs) along and among the arterioles and feed arteries that comprise vascular resistance networks. Whereas smooth muscle contraction of resistance vessels is enhanced by noradrenaline release along perivascular sympathetic nerves, the endothelium is integral to coordinating smooth muscle relaxation. Beyond producing nitric oxide in response to agonists and shear stress, endothelial cells (ECs) provide an effective conduit for conducting hyperpolarization along vessel branches and into surrounding SMCs through myoendothelial coupling. In turn, bidirectional signalling from SMCs into ECs enables the endothelium to moderate adrenergic vasoconstriction in response to sympathetic nerve activity. This review focuses on the endothelium as the cellular pathway that coordinates spreading vasodilatation. We discuss the nature and regulation of cell-to-cell coupling through gap junctions, bidirectional signalling between ECs and SMCs, and how oxidative stress during ageing may influence respective signalling pathways. Our recent findings illustrate the role of small (SK(Ca)) and intermediate (IK(Ca)) Ca(2+) activated K(+) channels as modulators of electrical conduction along the endothelium. Gaps in current understanding indicate the need to determine mechanisms that regulate intracellular Ca(2+) homeostasis and ion channel activation in the resistance vasculature with advancing age.
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Affiliation(s)
- Erik J Behringer
- Medical Pharmacology and Physiology, University of Missouri, Columbia, MO 65212, USA
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141
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Balut CM, Hamilton KL, Devor DC. Trafficking of intermediate (KCa3.1) and small (KCa2.x) conductance, Ca(2+)-activated K(+) channels: a novel target for medicinal chemistry efforts? ChemMedChem 2012; 7:1741-55. [PMID: 22887933 DOI: 10.1002/cmdc.201200226] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2012] [Revised: 07/09/2012] [Indexed: 12/22/2022]
Abstract
Ca(2+)-activated K(+) (KCa) channels play a pivotal role in the physiology of a wide variety of tissues and disease states, including vascular endothelia, secretory epithelia, certain cancers, red blood cells (RBC), neurons, and immune cells. Such widespread involvement has generated an intense interest in elucidating the function and regulation of these channels, with the goal of developing pharmacological strategies aimed at selective modulation of KCa channels in various disease states. Herein we give an overview of the molecular and functional properties of these channels and their therapeutic importance. We discuss the achievements made in designing pharmacological tools that control the function of KCa channels by modulating their gating properties. Moreover, this review discusses the recent advances in our understanding of KCa channel assembly and anterograde trafficking toward the plasma membrane, the micro-domains in which these channels are expressed within the cell, and finally the retrograde trafficking routes these channels take following endocytosis. As the regulation of intracellular trafficking by agonists as well as the protein-protein interactions that modify these events continue to be explored, we anticipate this will open new therapeutic avenues for the targeting of these channels based on the pharmacological modulation of KCa channel density at the plasma membrane.
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Affiliation(s)
- Corina M Balut
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA
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142
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A procyanidin trimer, C1, promotes NO production in rat aortic endothelial cells via both hyperpolarization and PI3K/Akt pathways. Eur J Pharmacol 2012; 692:52-60. [PMID: 22796647 DOI: 10.1016/j.ejphar.2012.07.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2012] [Revised: 06/28/2012] [Accepted: 07/03/2012] [Indexed: 01/07/2023]
Abstract
Procyanidins, which are condensed catechins, have been elucidated as absorbable polyphenols, but their health-benefits remain unclear. The aim of this study was, thus, to clarify the efficacy and mechanism of each procyanidin oligomer in NO activation in rat aortic endothelial cells (RAECs). Treatment of RAECs with 50μM procyanidin C1 (4β→8 trimer) resulted in a time- and dose-dependent hyperpolarization using the membrane potential-sensitive probe bis-(1,3-dibutylbarbituric acid) trimethine oxonol, while no effect was observed for (-)-epicatechin (a monomer) and procyanidin B2 (4β→8 dimer). The C1-induced hyperpolarization was inhibited by iberiotoxin, a specific inhibitor of large-conductance Ca(2+)-activated K(+) (BK(Ca)) channel, as well as 2-aminoethyl diphenylborinate (2-APB), a store-operated Ca(2+) entry inhibitor. Procyanidin C1 caused a significant increase in NO production from RAECs via phosphorylation of both eNOS and Akt, and the effect was completely inhibited by N(G)-monomethyl-l-arginine or combined treatment with iberiotoxin and the phosphatidylinositol 3-kinase (PI3K) specific inhibitor, wortmannin, as well as combined treatment with 2-APB and wortmannin. Taken together, these findings provide critical evidence that procyanidin C1, but not B2, has potential to induce NO production in RAECs via both Ca(2+)-dependent BK(Ca) channel-mediated hyperpolarization and Ca(2+)-independent PI3K/Akt pathways.
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143
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Fiorim J, Ribeiro Júnior RF, Azevedo BF, Simões MR, Padilha AS, Stefanon I, Alonso MJ, Salaices M, Vassallo DV. Activation of K+ channels and Na+/K+ ATPase prevents aortic endothelial dysfunction in 7-day lead-treated rats. Toxicol Appl Pharmacol 2012; 262:22-31. [DOI: 10.1016/j.taap.2012.04.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Revised: 04/10/2012] [Accepted: 04/12/2012] [Indexed: 11/15/2022]
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144
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Senadheera S, Kim Y, Grayson TH, Toemoe S, Kochukov MY, Abramowitz J, Housley GD, Bertrand RL, Chadha PS, Bertrand PP, Murphy TV, Tare M, Birnbaumer L, Marrelli SP, Sandow SL. Transient receptor potential canonical type 3 channels facilitate endothelium-derived hyperpolarization-mediated resistance artery vasodilator activity. Cardiovasc Res 2012; 95:439-47. [PMID: 22721989 DOI: 10.1093/cvr/cvs208] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
AIMS Microdomain signalling mechanisms underlie key aspects of artery function and the modulation of intracellular calcium, with transient receptor potential (TRP) channels playing an integral role. This study determines the distribution and role of TRP canonical type 3 (C3) channels in the control of endothelium-derived hyperpolarization (EDH)-mediated vasodilator tone in rat mesenteric artery. METHODS AND RESULTS TRPC3 antibody specificity was verified using rat tissue, human embryonic kidney (HEK)-293 cells stably transfected with mouse TRPC3 cDNA, and TRPC3 knock-out (KO) mouse tissue using western blotting and confocal and ultrastructural immunohistochemistry. TRPC3-Pyr3 (ethyl-1-(4-(2,3,3-trichloroacrylamide)phenyl)-5-(trifluoromethyl)-1H-pyrazole-4-carboxylate) specificity was verified using patch clamp of mouse mesenteric artery endothelial and TRPC3-transfected HEK cells, and TRPC3 KO and wild-type mouse aortic endothelial cell calcium imaging and mesenteric artery pressure myography. TRPC3 distribution, expression, and role in EDH-mediated function were examined in rat mesenteric artery using immunohistochemistry and western blotting, and pressure myography and endothelial cell membrane potential recordings. In rat mesenteric artery, TRPC3 was diffusely distributed in the endothelium, with approximately five-fold higher expression at potential myoendothelial microdomain contact sites, and immunoelectron microscopy confirmed TRPC3 at these sites. Western blotting and endothelial damage confirmed primary endothelial TRPC3 expression. In rat mesenteric artery endothelial cells, Pyr3 inhibited hyperpolarization generation, and with individual SK(Ca) (apamin) or IK(Ca) (TRAM-34) block, Pyr3 abolished the residual respective IK(Ca)- and SK(Ca)-dependent EDH-mediated vasodilation. CONCLUSION The spatial localization of TRPC3 and associated channels, receptors, and calcium stores are integral for myoendothelial microdomain function. TRPC3 facilitates endothelial SK(Ca) and IK(Ca) activation, as key components of EDH-mediated vasodilator activity and for regulating mesenteric artery tone.
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Affiliation(s)
- Sevvandi Senadheera
- Department of Physiology, School of Medical Sciences, Faculty of Medicine, University of New South Wales, Sydney 2052, Australia.
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Howitt L, Grayson TH, Morris MJ, Sandow SL, Murphy TV. Dietary obesity increases NO and inhibits BKCa-mediated, endothelium-dependent dilation in rat cremaster muscle artery: association with caveolins and caveolae. Am J Physiol Heart Circ Physiol 2012; 302:H2464-76. [DOI: 10.1152/ajpheart.00965.2011] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Obesity is a risk factor for hypertension and other vascular disease. The aim of this study was to examine the effect of diet-induced obesity on endothelium-dependent dilation of rat cremaster muscle arterioles. Male Sprague-Dawley rats (213 ± 1 g) were fed a cafeteria-style high-fat or control diet for 16–20 wk. Control rats weighed 558 ± 7 g compared with obese rats 762 ± 12 g ( n = 52–56; P < 0.05). Diet-induced obesity had no effect on acetylcholine (ACh)-induced dilation of isolated, pressurized (70 mmHg) arterioles, but sodium nitroprusside (SNP)-induced vasodilation was enhanced. ACh-induced dilation of arterioles from control rats was abolished by a combination of the KCa blockers apamin, 1-[(2-chlorophenyl)diphenylmethyl]-1H-pyrazole (TRAM-34), and iberiotoxin (IBTX; all 0.1 μmol/l), with no apparent role for nitric oxide (NO). In arterioles from obese rats, however, IBTX had no effect on responses to ACh while the NO synthase (NOS)/guanylate cyclase inhibitors Nω-nitro-l-arginine methyl ester (l-NAME; 100 μmol/l)/1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ; 10 μmol/l) partially inhibited ACh-induced dilation. Furthermore, NOS activity (but not endothelial NOS expression) was increased in arteries from obese rats. l-NAME/ODQ alone or removal of the endothelium constricted arterioles from obese but not control rats. Expression of caveolin-1 and -2 oligomers (but not monomers or caveolin-3) was increased in arterioles from obese rats. The number of caveolae was reduced in the endothelium of arteries, and caveolae density was increased at the ends of smooth muscle cells from obese rats. Diet-induced obesity abolished the contribution of large-conductance Ca2+-activated K+ channel to ACh-mediated endothelium-dependent dilation of rat cremaster muscle arterioles, while increasing NOS activity and inducing an NO-dependent component.
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Affiliation(s)
- Lauren Howitt
- Department of Physiology, School of Medical Sciences, University of New South Wales, Sydney, Australia; and
| | - T. Hilton Grayson
- Pharmacology, School of Medical Sciences, University of New South Wales, Sydney, Australia
| | - Margaret J. Morris
- Pharmacology, School of Medical Sciences, University of New South Wales, Sydney, Australia
| | - Shaun L. Sandow
- Department of Physiology, School of Medical Sciences, University of New South Wales, Sydney, Australia; and
- Pharmacology, School of Medical Sciences, University of New South Wales, Sydney, Australia
| | - Timothy V. Murphy
- Department of Physiology, School of Medical Sciences, University of New South Wales, Sydney, Australia; and
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Requirement for functional BK channels in maintaining oscillation in venomotor tone revealed by species differences in expression of the β1 accessory subunits. J Cardiovasc Pharmacol 2012; 59:29-36. [PMID: 21885988 DOI: 10.1097/fjc.0b013e318233614c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
We determined the possible role of large-conductance Ca2+-activated K (BK) channels in regulation of venous tone in small capacitance veins and blood pressure. In rat mesenteric venous smooth muscle cells (MV SMC), BK channel α- and β1-subunits were coexpressed, unitary BK currents were detected, and single-channel currents were sensitive to voltage and [Ca2+]i. Rat MV SMCs displayed Ca sparks and iberiotoxin-sensitive spontaneous transient outward currents. Under resting conditions in vitro, rat MV exhibited nifedipine-sensitive spontaneous oscillatory constrictions. Blockade of BK channels by paxilline and Ca2+ sparks by ryanodine constricted rat MV. Nifedipine caused venodilation and blocked paxilline-induced, KCl-induced (20 mM), and BayK8644-induced contraction. Acute inhibition of BK channels with iberiotoxin in vivo increased blood pressure and reduced venous capacitance, measured as an increase in mean circulatory filling pressure in conscious rats. BK channel α-subunits and L-type Ca2+ channel α1-C subunits are expressed in murine MV. However, these channels are not functional because murine MV lack nifedipine-sensitive basal tone and rhythmic constrictions. Murine MV were also insensitive to paxilline, ryanodine, KCl, and BayK8644, consistent with our previous studies showing that murine MV do not have BK β1-subunits. These data show that not only there are species-dependent properties in ion channel control of venomotor tone but also BK channels are required for rhythmic oscillations in venous tone.
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147
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Garaliene V, Barsys V, Jakuška P, Benetis R. Action of calcium antagonists and agonists on isolated human thoracic arteries used for coronary artery bypass grafting. Pharmacol Rep 2012; 64:733-8. [DOI: 10.1016/s1734-1140(12)70868-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2011] [Revised: 12/29/2011] [Indexed: 10/25/2022]
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148
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Behringer EJ, Segal SS. Tuning electrical conduction along endothelial tubes of resistance arteries through Ca(2+)-activated K(+) channels. Circ Res 2012; 110:1311-21. [PMID: 22492531 DOI: 10.1161/circresaha.111.262592] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
RATIONALE Electrical conduction through gap junction channels between endothelial cells of resistance vessels is integral to blood flow control. Small and intermediate-conductance Ca(2+)-activated K(+) channels (SK(Ca)/IK(Ca)) initiate electrical signals in endothelial cells, but it is unknown whether SK(Ca)/IK(Ca) activation alters signal transmission along the endothelium. OBJECTIVE We tested the hypothesis that SK(Ca)/IK(Ca) activity regulates electrical conduction along the endothelium of resistance vessels. METHODS AND RESULTS Freshly isolated endothelial cell tubes (60 μm wide; 1-3 mm long; cell length, ≈35 μm) from mouse skeletal muscle feed (superior epigastric) arteries were studied using dual intracellular microelectrodes. Current was injected (±0.1-3 nA) at site 1 while recording membrane potential (V(m)) at site 2 (separation distance=50-2000 μm). SK(Ca)/IK(Ca) activation (NS309, 1 μmol/L) reduced the change in V(m) along endothelial cell tubes by ≥50% and shortened the electrical length constant (λ) from 1380 to 850 μm (P<0.05) while intercellular dye transfer (propidium iodide) was maintained. Activating SK(Ca)/IK(Ca) with acetylcholine or SKA-31 also reduced electrical conduction. These effects of SK(Ca)/IK(Ca) activation persisted when hyperpolarization (>30 mV) was prevented with 60 mmol/L [K(+)](o). Conversely, blocking SK(Ca)/IK(Ca) (apamin+charybdotoxin) depolarized cells by ≈10 mV and enhanced electrical conduction (ie, changes in V(m)) by ≈30% (P<0.05). CONCLUSIONS These findings illustrate a novel role for SK(Ca)/IK(Ca) activity in tuning electrical conduction along the endothelium of resistance vessels by governing signal dissipation through changes in membrane resistance. Voltage-insensitive ion channels can thereby tune intercellular electrical signaling independent from gap junction channels.
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Affiliation(s)
- Erik J Behringer
- Medical Pharmacology and Physiology, University of Missouri, Columbia, MO 65212, USA
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149
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Matsumoto T, Szasz T, Tostes RC, Webb RC. Impaired β-adrenoceptor-induced relaxation in small mesenteric arteries from DOCA-salt hypertensive rats is due to reduced K(Ca) channel activity. Pharmacol Res 2012; 65:537-45. [PMID: 22388053 DOI: 10.1016/j.phrs.2012.02.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Revised: 02/07/2012] [Accepted: 02/14/2012] [Indexed: 10/28/2022]
Abstract
β-Adrenoceptor (β-AR)-mediated relaxation plays an important role in the regulation of vascular tone. β-AR-mediated vascular relaxation is reduced in various disease states and aging. We hypothesized that β-AR-mediated vasodilatation is impaired in DOCA-salt hypertension due to alterations in the cAMP pathway. β-AR-mediated relaxation was determined in small mesenteric arteries from DOCA-salt hypertensive and control uninephrectomized (Uni) rats. To exclude nitric oxide (NO) and cyclooxygenase (COX) pathways, relaxation responses were determined in the presence of l-NNA and indomethacin, NO synthase inhibitor and COX inhibitors, respectively. Isoprenaline (ISO)-induced relaxation was reduced in arteries from DOCA-salt compared to Uni rats. Protein kinase A (PKA) inhibitors (H89 or Rp-cAMPS) or adenylyl cyclase inhibitor (SQ22536) did not abolish the difference in ISO-induced relaxation between the groups. Forskolin (adenylyl cyclase activator)-induced relaxation was similar between the groups. The inhibition of IK(Ca)/SK(Ca) channels (TRAM-34 plus UCL1684) or BK(Ca) channels (iberiotoxin) reduced ISO-induced relaxation only in Uni rats and abolished the relaxation differences between the groups. The expression of SK(Ca) channel was decreased in DOCA-salt arteries. The expression of BK(Ca) channel α subunit was increased whereas the expression of BK(Ca) channel β subunit was decreased in DOCA-salt arteries. The expression of receptor for activated C kinase 1 (RACK1), which is a binding protein for BK(Ca) channel and negatively modulates its activity, was increased in DOCA-salt arteries. These results suggest that the impairment of β-AR-mediated relaxation in DOCA-salt mesenteric arteries may be attributable to altered IK(Ca)/SK(Ca) and/or BK(Ca) channels activities rather than cAMP/PKA pathway. Impaired β-AR-stimulated BK(Ca) channel activity may be due to the imbalance between its subunit expressions and RACK1 upregulation.
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Affiliation(s)
- Takayuki Matsumoto
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo 142-8501, Japan.
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150
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Kvietys PR, Granger DN. Role of reactive oxygen and nitrogen species in the vascular responses to inflammation. Free Radic Biol Med 2012; 52:556-592. [PMID: 22154653 PMCID: PMC3348846 DOI: 10.1016/j.freeradbiomed.2011.11.002] [Citation(s) in RCA: 213] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2011] [Revised: 11/04/2011] [Accepted: 11/04/2011] [Indexed: 12/23/2022]
Abstract
Inflammation is a complex and potentially life-threatening condition that involves the participation of a variety of chemical mediators, signaling pathways, and cell types. The microcirculation, which is critical for the initiation and perpetuation of an inflammatory response, exhibits several characteristic functional and structural changes in response to inflammation. These include vasomotor dysfunction (impaired vessel dilation and constriction), the adhesion and transendothelial migration of leukocytes, endothelial barrier dysfunction (increased vascular permeability), blood vessel proliferation (angiogenesis), and enhanced thrombus formation. These diverse responses of the microvasculature largely reflect the endothelial cell dysfunction that accompanies inflammation and the central role of these cells in modulating processes as varied as blood flow regulation, angiogenesis, and thrombogenesis. The importance of endothelial cells in inflammation-induced vascular dysfunction is also predicated on the ability of these cells to produce and respond to reactive oxygen and nitrogen species. Inflammation seems to upset the balance between nitric oxide and superoxide within (and surrounding) endothelial cells, which is necessary for normal vessel function. This review is focused on defining the molecular targets in the vessel wall that interact with reactive oxygen species and nitric oxide to produce the characteristic functional and structural changes that occur in response to inflammation. This analysis of the literature is consistent with the view that reactive oxygen and nitrogen species contribute significantly to the diverse vascular responses in inflammation and supports efforts that are directed at targeting these highly reactive species to maintain normal vascular health in pathological conditions that are associated with acute or chronic inflammation.
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Affiliation(s)
- Peter R Kvietys
- College of Medicine, Alfaisal University, Riyadh, Saudi Arabia
| | - D Neil Granger
- Department of Molecular & Cellular Physiology, Louisiana State University Health Sciences Center, Shreveport, LA 71130-3932, USA.
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