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Cavarretta F, Jaeger D. Modeling Synaptic Integration of Bursty and β Oscillatory Inputs in Ventromedial Motor Thalamic Neurons in Normal and Parkinsonian States. eNeuro 2023; 10:ENEURO.0237-23.2023. [PMID: 37989589 PMCID: PMC10726287 DOI: 10.1523/eneuro.0237-23.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Revised: 10/16/2023] [Accepted: 11/05/2023] [Indexed: 11/23/2023] Open
Abstract
The ventromedial motor thalamus (VM) is implicated in multiple motor functions and occupies a central position in the cortico-basal ganglia-thalamocortical loop. It integrates glutamatergic inputs from motor cortex (MC) and motor-related subcortical areas, and it is a major recipient of inhibition from basal ganglia. Previous in vitro experiments performed in mice showed that dopamine depletion enhances the excitability of thalamocortical (TC) neurons in VM due to reduced M-type potassium currents. To understand how these excitability changes impact synaptic integration in vivo, we constructed biophysically detailed mouse VM TC model neurons fit to normal and dopamine-depleted conditions, using the NEURON simulator. These models allowed us to assess the influence of excitability changes with dopamine depletion on the integration of synaptic inputs expected in vivo We found that VM neuron models in the dopamine-depleted state showed increased firing rates with the same synaptic inputs. Synchronous bursting in inhibitory input from the substantia nigra pars reticulata (SNR), as observed in parkinsonian conditions, evoked a postinhibitory firing rate increase with a longer duration in dopamine-depleted than control conditions, due to different M-type potassium channel densities. With β oscillations in the inhibitory inputs from SNR and the excitatory inputs from cortex, we observed spike-phase locking in the activity of the models in normal and dopamine-depleted states, which relayed and amplified the oscillations of the inputs, suggesting that the increased β oscillations observed in VM of parkinsonian animals are predominantly a consequence of changes in the presynaptic activity rather than changes in intrinsic properties.
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Affiliation(s)
| | - Dieter Jaeger
- Department of Biology, Emory University, Atlanta, GA 30322
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2
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Shorthouse D, Zhuang L, Rahrmann EP, Kosmidou C, Wickham Rahrmann K, Hall M, Greenwood B, Devonshire G, Gilbertson RJ, Fitzgerald RC, Hall BA. KCNQ potassium channels modulate Wnt activity in gastro-oesophageal adenocarcinomas. Life Sci Alliance 2023; 6:e202302124. [PMID: 37748809 PMCID: PMC10520261 DOI: 10.26508/lsa.202302124] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 09/11/2023] [Accepted: 09/11/2023] [Indexed: 09/27/2023] Open
Abstract
Voltage-sensitive potassium channels play an important role in controlling membrane potential and ionic homeostasis in the gut and have been implicated in gastrointestinal (GI) cancers. Through large-scale analysis of 897 patients with gastro-oesophageal adenocarcinomas (GOAs) coupled with in vitro models, we find KCNQ family genes are mutated in ∼30% of patients, and play therapeutically targetable roles in GOA cancer growth. KCNQ1 and KCNQ3 mediate the WNT pathway and MYC to increase proliferation through resultant effects on cadherin junctions. This also highlights novel roles of KCNQ3 in non-excitable tissues. We also discover that activity of KCNQ3 sensitises cancer cells to existing potassium channel inhibitors and that inhibition of KCNQ activity reduces proliferation of GOA cancer cells. These findings reveal a novel and exploitable role of potassium channels in the advancement of human cancer, and highlight that supplemental treatments for GOAs may exist through KCNQ inhibitors.
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Affiliation(s)
- David Shorthouse
- https://ror.org/02jx3x895 Department of Medical Physics and Biomedical Engineering, Malet Place Engineering Building, University College London, London, UK
| | - Lizhe Zhuang
- Institute for Early Detection, CRUK Cambridge Centre, Cambridge, UK
| | - Eric P Rahrmann
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, University of Cambridge, Cambridge, UK
| | | | | | - Michael Hall
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, University of Cambridge, Cambridge, UK
| | - Benedict Greenwood
- https://ror.org/02jx3x895 Department of Medical Physics and Biomedical Engineering, Malet Place Engineering Building, University College London, London, UK
| | - Ginny Devonshire
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, University of Cambridge, Cambridge, UK
| | - Richard J Gilbertson
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, University of Cambridge, Cambridge, UK
| | | | - Benjamin A Hall
- https://ror.org/02jx3x895 Department of Medical Physics and Biomedical Engineering, Malet Place Engineering Building, University College London, London, UK
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3
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Peixoto-Neves D, Kanthakumar P, Afolabi JM, Soni H, Buddington RK, Adebiyi A. K V7.1 channel blockade inhibits neonatal renal autoregulation triggered by a step decrease in arterial pressure. Am J Physiol Renal Physiol 2022; 322:F197-F207. [PMID: 35001664 PMCID: PMC8816635 DOI: 10.1152/ajprenal.00568.2020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
KV7 channels, the voltage-gated K+ channels encoded by KCNQ genes, mediate heterogeneous vascular responses in rodents. Postnatal changes in the functional expression of KV7 channels have been reported in rodent saphenous arteries, but their physiological function in the neonatal renal vascular bed is unclear. Here, we report that, unlike adult pigs, only KCNQ1 (KV7.1) out of the five members of KCNQ genes was detected in neonatal pig renal microvessels. KCNQ1 is present in fetal pig kidneys as early as day 50 of gestation, and the level of expression remains the same up to postnatal day 21. Activation of renal vascular smooth muscle cell (SMC) KV7.1 stimulated whole cell currents, inhibited by HMR1556 (HMR), a selective KV7.1 blocker. HMR did not change the steady-state diameter of isolated renal microvessels. Similarly, intrarenal artery infusion of HMR did not alter mean arterial pressure, renal blood flow, and renal vascular resistance in the pigs. An ∼20 mmHg reduction in mean arterial pressure evoked effective autoregulation of renal blood flow, which HMR inhibited. We conclude that 1) the expression of KCNQ isoforms in porcine renal microvessels is dependent on kidney maturation, 2) KV7.1 is functionally expressed in neonatal pig renal vascular SMCs, 3) a decrease in arterial pressure up to 20 mmHg induces renal autoregulation in neonatal pigs, and 4) SMC KV7.1 does not control basal renal vascular tone but contributes to neonatal renal autoregulation triggered by a step decrease in arterial pressure.NEW & NOTEWORTHY KV7.1 is present in fetal pig kidneys as early as day 50 of gestation, and the level of expression remains the same up to postnatal day 21. KV7.1 is functionally expressed in neonatal pig renal vascular smooth muscle cells (SMCs). A decrease in arterial pressure up to 20 mmHg induces renal autoregulation in neonatal pigs. Although SMC KV7.1 does not control basal renal vascular resistance, its inhibition blunts neonatal renal autoregulation engendered by a step decrease in arterial pressure.
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Affiliation(s)
- Dieniffer Peixoto-Neves
- 1Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee
| | | | - Jeremiah M. Afolabi
- 1Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee
| | - Hitesh Soni
- 1Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee
| | | | - Adebowale Adebiyi
- 1Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee
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Aiba I, Noebels JL. Kcnq2/Kv7.2 controls the threshold and bi-hemispheric symmetry of cortical spreading depolarization. Brain 2021; 144:2863-2878. [PMID: 33768249 PMCID: PMC8536937 DOI: 10.1093/brain/awab141] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Revised: 02/22/2021] [Accepted: 03/20/2021] [Indexed: 12/03/2022] Open
Abstract
Spreading depolarization is a slowly propagating wave of massive cellular depolarization associated with acute brain injury and migraine aura. Genetic studies link depolarizing molecular defects in Ca2+ flux, Na+ current in interneurons, and glial Na+-K+ ATPase with spreading depolarization susceptibility, emphasizing the important roles of synaptic activity and extracellular ionic homeostasis in determining spreading depolarization threshold. In contrast, although gene mutations in voltage-gated potassium ion channels that shape intrinsic membrane excitability are frequently associated with epilepsy susceptibility, it is not known whether epileptogenic mutations that regulate membrane repolarization also modify spreading depolarization threshold and propagation. Here we report that the Kcnq2/Kv7.2 potassium channel subunit, frequently mutated in developmental epilepsy, is a spreading depolarization modulatory gene with significant control over the seizure-spreading depolarization transition threshold, bi-hemispheric cortical expression, and diurnal temporal susceptibility. Chronic DC-band cortical EEG recording from behaving conditional Kcnq2 deletion mice (Emx1cre/+::Kcnq2flox/flox) revealed spontaneous cortical seizures and spreading depolarization. In contrast to the related potassium channel deficient model, Kv1.1-KO mice, spontaneous cortical spreading depolarizations in Kcnq2 cKO mice are tightly coupled to the terminal phase of seizures, arise bilaterally, and are observed predominantly during the dark phase. Administration of the non-selective Kv7.2 inhibitor XE991 to Kv1.1-KO mice partly reproduced the Kcnq2 cKO-like spreading depolarization phenotype (tight seizure coupling and bilateral symmetry) in these mice, indicating that Kv7.2 currents can directly and actively modulate spreading depolarization properties. In vitro brain slice studies confirmed that Kcnq2/Kv7.2 depletion or pharmacological inhibition intrinsically lowers the cortical spreading depolarization threshold, whereas pharmacological Kv7.2 activators elevate the threshold to multiple depolarizing and hypometabolic spreading depolarization triggers. Together these results identify Kcnq2/Kv7.2 as a distinctive spreading depolarization regulatory gene, and point to spreading depolarization as a potentially significant pathophysiological component of KCNQ2-linked epileptic encephalopathy syndromes. Our results also implicate KCNQ2/Kv7.2 channel activation as a potential adjunctive therapeutic target to inhibit spreading depolarization incidence.
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Affiliation(s)
- Isamu Aiba
- Department of Neurology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Jeffrey L Noebels
- Department of Neurology, Baylor College of Medicine, Houston, TX 77030, USA
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5
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Farrell B, Skidmore BL, Rajasekharan V, Brownell WE. A novel theoretical framework reveals more than one voltage-sensing pathway in the lateral membrane of outer hair cells. J Gen Physiol 2021; 152:151746. [PMID: 32384538 PMCID: PMC7335013 DOI: 10.1085/jgp.201912447] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Accepted: 03/18/2020] [Indexed: 11/20/2022] Open
Abstract
Outer hair cell (OHC) electromotility amplifies acoustic vibrations throughout the frequency range of hearing. Electromotility requires that the lateral membrane protein prestin undergo a conformational change upon changes in the membrane potential to produce an associated displacement charge. The magnitude of the charge displaced and the mid-reaction potential (when one half of the charge is displaced) reflects whether the cells will produce sufficient gain at the resting membrane potential to boost sound in vivo. Voltage clamp measurements performed under near-identical conditions ex vivo show the charge density and mid-reaction potential are not always the same, confounding interpretation of the results. We compare the displacement charge measurements in OHCs from rodents with a theory shown to exhibit good agreement with in silico simulations of voltage-sensing reactions in membranes. This model equates the charge density to the potential difference between two pseudo-equilibrium states of the sensors when they are in a stable conformation and not contributing to the displacement current. The model predicts this potential difference to be one half of its value midway into the reaction, when one equilibrium conformation transforms to the other pseudo-state. In agreement with the model, we find the measured mid-reaction potential to increase as the charge density decreases to exhibit a negative slope of ∼1/2. This relationship suggests that the prestin sensors exhibit more than one stable hyperpolarized state and that voltage sensing occurs by more than one pathway. We determine the electric parameters for prestin sensors and use the analytical expressions of the theory to estimate the energy barriers for the two voltage-dependent pathways. This analysis explains the experimental results, supports the theoretical approach, and suggests that voltage sensing occurs by more than one pathway to enable amplification throughout the frequency range of hearing.
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Affiliation(s)
- Brenda Farrell
- Bobby R. Alford Department of Otolaryngology and Head & Neck Surgery, Baylor College of Medicine, Houston, TX
| | - Benjamin L Skidmore
- Bobby R. Alford Department of Otolaryngology and Head & Neck Surgery, Baylor College of Medicine, Houston, TX
| | - Vivek Rajasekharan
- Bobby R. Alford Department of Otolaryngology and Head & Neck Surgery, Baylor College of Medicine, Houston, TX
| | - William E Brownell
- Bobby R. Alford Department of Otolaryngology and Head & Neck Surgery, Baylor College of Medicine, Houston, TX
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6
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Shvetsova AA, Gaynullina DK, Tarasova OS, Schubert R. Remodeling of Arterial Tone Regulation in Postnatal Development: Focus on Smooth Muscle Cell Potassium Channels. Int J Mol Sci 2021; 22:ijms22115413. [PMID: 34063769 PMCID: PMC8196626 DOI: 10.3390/ijms22115413] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 05/15/2021] [Accepted: 05/18/2021] [Indexed: 11/30/2022] Open
Abstract
Maturation of the cardiovascular system is associated with crucial structural and functional remodeling. Thickening of the arterial wall, maturation of the sympathetic innervation, and switching of the mechanisms of arterial contraction from calcium-independent to calcium-dependent occur during postnatal development. All these processes promote an almost doubling of blood pressure from the moment of birth to reaching adulthood. This review focuses on the developmental alterations of potassium channels functioning as key smooth muscle membrane potential determinants and, consequently, vascular tone regulators. We present evidence that the pattern of potassium channel contribution to vascular control changes from Kir2, Kv1, Kv7 and TASK-1 channels to BKCa channels with maturation. The differences in the contribution of potassium channels to vasomotor tone at different stages of postnatal life should be considered in treatment strategies of cardiovascular diseases associated with potassium channel malfunction.
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Affiliation(s)
- Anastasia A. Shvetsova
- Department of Human and Animal Physiology, Faculty of Biology, M.V. Lomonosov Moscow State University, 119234 Moscow, Russia; (D.K.G.); (O.S.T.)
- Correspondence:
| | - Dina K. Gaynullina
- Department of Human and Animal Physiology, Faculty of Biology, M.V. Lomonosov Moscow State University, 119234 Moscow, Russia; (D.K.G.); (O.S.T.)
- Department of Physiology, Russian National Research Medical University, 117997 Moscow, Russia
| | - Olga S. Tarasova
- Department of Human and Animal Physiology, Faculty of Biology, M.V. Lomonosov Moscow State University, 119234 Moscow, Russia; (D.K.G.); (O.S.T.)
- Laboratory of Exercise Physiology, State Research Center of the Russian Federation-Institute for Biomedical Problems, Russian Academy of Sciences, 123007 Moscow, Russia
| | - Rudolf Schubert
- Physiology, Institute of Theoretical Medicine, Medical Faculty, University of Augsburg, 86159 Augsburg, Germany;
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7
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Revill AL, Katzell A, Del Negro CA, Milsom WK, Funk GD. KCNQ Current Contributes to Inspiratory Burst Termination in the Pre-Bötzinger Complex of Neonatal Rats in vitro. Front Physiol 2021; 12:626470. [PMID: 33927636 PMCID: PMC8078421 DOI: 10.3389/fphys.2021.626470] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 02/23/2021] [Indexed: 12/23/2022] Open
Abstract
The pre-Bötzinger complex (preBötC) of the ventral medulla generates the mammalian inspiratory breathing rhythm. When isolated in explants and deprived of synaptic inhibition, the preBötC continues to generate inspiratory-related rhythm. Mechanisms underlying burst generation have been investigated for decades, but cellular and synaptic mechanisms responsible for burst termination have received less attention. KCNQ-mediated K+ currents contribute to burst termination in other systems, and their transcripts are expressed in preBötC neurons. Therefore, we tested the hypothesis that KCNQ channels also contribute to burst termination in the preBötC. We recorded KCNQ-like currents in preBötC inspiratory neurons in neonatal rat slices that retain respiratory rhythmicity. Blocking KCNQ channels with XE991 or linopirdine (applied via superfusion or locally) increased inspiratory burst duration by 2- to 3-fold. By contrast, activation of KCNQ with retigabine decreased inspiratory burst duration by ~35%. These data from reduced preparations suggest that the KCNQ current in preBötC neurons contributes to inspiratory burst termination.
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Affiliation(s)
- Ann L. Revill
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
- Department of Physiology, University of Alberta, Edmonton, AB, Canada
- Women and Children’s Health Research Institute, University of Alberta, Edmonton, AB, Canada
| | - Alexis Katzell
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
- Department of Physiology, University of Alberta, Edmonton, AB, Canada
- Women and Children’s Health Research Institute, University of Alberta, Edmonton, AB, Canada
| | | | - William K. Milsom
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada
| | - Gregory D. Funk
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
- Department of Physiology, University of Alberta, Edmonton, AB, Canada
- Women and Children’s Health Research Institute, University of Alberta, Edmonton, AB, Canada
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8
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Beck L, Pinilla E, Arcanjo DDR, Hernanz R, Prat-Duran J, Petersen AG, Köhler R, Sheykhzade M, Comerma-Steffensen S, Simonsen U. Pirfenidone Is a Vasodilator: Involvement of K V7 Channels in the Effect on Endothelium-Dependent Vasodilatation in Type-2 Diabetic Mice. Front Pharmacol 2021; 11:619152. [PMID: 33643042 PMCID: PMC7906977 DOI: 10.3389/fphar.2020.619152] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Accepted: 12/30/2020] [Indexed: 12/27/2022] Open
Abstract
Endothelial cell dysfunction and fibrosis are associated with worsening of the prognosis in patients with cardiovascular disease. Pirfenidone has a direct antifibrotic effect, but vasodilatation may also contribute to the effects of pirfenidone. Therefore, in a first study we investigated the mechanisms involved in the relaxant effect of pirfenidone in rat intrapulmonary arteries and coronary arteries from normal mice. Then in a second study, we investigated whether pirfenidone restores endothelial function in the aorta and mesenteric arteries from diabetic animals. From 16–18-week old normal male C57BL/6 mice and normoglycemic (db/db+), and type 2 diabetic (db/db) male and female mice, arteries were mounted in microvascular isometric myographs for functional studies, and immunoblotting was performed. In rat pulmonary arteries and mouse coronary arteries, pirfenidone induced relaxations, which were inhibited in preparations without endothelium. In mouse coronary arteries, pirfenidone relaxation was inhibited in the presence of a nitric oxide (NO) synthase inhibitor, NG-nitro-l-arginine (L-NOARG), a blocker of large-conductance calcium-activated potassium channels (BKCa), iberiotoxin, and a blocker of KV7 channels, XE991. Patch clamp studies in vascular smooth muscle revealed pirfenidone increased iberiotoxin-sensitive current. In the aorta and mesenteric small arteries from diabetic db/db mice relaxations induced by the endothelium-dependent vasodilator, acetylcholine, were markedly reduced compared to db/db + mice. Pirfenidone enhanced the relaxations induced by acetylcholine in the aorta from diabetic male and female db/db mice. An opener of KV7 channels, flupirtine, had the same effect as pirfenidone. XE991 reduced the effect of pirfenidone and flupirtine and further reduced acetylcholine relaxations in the aorta. In the presence of iberiotoxin, pirfenidone still increased acetylcholine relaxation in aorta from db/db mice. Immunoblotting for KV7.4, KV7.5, and BKCa channel subunits were unaltered in aorta from db/db mice. Pirfenidone failed to improve acetylcholine relaxation in mesenteric arteries, and neither changed acetylcholine-induced transient decreases in blood pressure in db/db+ and db/db mice. In conclusion, pirfenidone vasodilates pulmonary and coronary arteries. In coronary arteries from normal mice, pirfenidone induces NO-dependent vasodilatation involving BKCa and KV7 channels. Pirfenidone improves endothelium-dependent vasodilatation in aorta from diabetic animals by a mechanism involving voltage-gated KV7 channels, a mechanism that may contribute to the antifibrotic effect of pirfenidone.
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Affiliation(s)
- Lilliana Beck
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Aarhus University, Aarhus, Denmark
| | - Estéfano Pinilla
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Aarhus University, Aarhus, Denmark.,Department of Physiology, Faculty of Pharmacy, Universidad Complutense, Madrid, Spain
| | - Daniel Dias Rufino Arcanjo
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Aarhus University, Aarhus, Denmark.,Department of Biophysics and Physiology, Laboratory of Functional and Molecular Studies in Physiopharmacology, Federal University of Piauí, Teresina, Brazil
| | - Raquel Hernanz
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Aarhus University, Aarhus, Denmark.,Departamento de Ciencias Básicas de la Salud, Universidad Rey Juan Carlos, Alcorcón, Spain
| | - Judit Prat-Duran
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Aarhus University, Aarhus, Denmark
| | - Asbjørn Graver Petersen
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Aarhus University, Aarhus, Denmark
| | - Ralf Köhler
- Aragón Agency for Research and Development (ARAID), Zaragoza, Spain
| | - Majid Sheykhzade
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Simon Comerma-Steffensen
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Aarhus University, Aarhus, Denmark.,Department of Biomedical Sciences/Animal Physiology, Faculty of Veterinary, Central University of Venezuela, Maracay, Venezuela
| | - Ulf Simonsen
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Aarhus University, Aarhus, Denmark
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Ma D, Gaynullina D, Schmidt N, Mladenov M, Schubert R. The Functional Availability of Arterial Kv7 Channels Is Suppressed Considerably by Large-Conductance Calcium-Activated Potassium Channels in 2- to 3-Month Old but Not in 10- to 15-Day Old Rats. Front Physiol 2020; 11:597395. [PMID: 33384611 PMCID: PMC7770149 DOI: 10.3389/fphys.2020.597395] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 11/24/2020] [Indexed: 01/26/2023] Open
Abstract
Background Voltage-gated potassium (Kv) channels, especially Kv7 channels, are major potassium channels identified in vascular smooth muscle cells with a great, albeit differential functional impact in various vessels. Vascular smooth muscle Kv7 channels always coexist with other K channels, in particular with BK channels. BK channels differ in the extent to which they influence vascular contractility. Whether this difference also causes the variability in the functional impact of Kv7 channels is unknown. Therefore, this study addressed the hypothesis that the functional impact of Kv7 channels depends on BK channels. Experimental Approach Experiments were performed on young and adult rat gracilis and saphenous arteries using real-time PCR as well as pressure and wire myography. Key Results Several subfamily members of Kv7 (KCNQ) and BK channels were expressed in saphenous and gracilis arteries: the highest expression was observed for BKα, BKβ1 and KCNQ4. Arterial contractility was assessed with methoxamine-induced contractions and pressure-induced myogenic responses. In vessels of adult rats, inhibition of Kv7 channels or BK channels by XE991 or IBTX, respectively enhanced arterial contractility to a similar degree, whereas activation of Kv7 channels or BK channels by retigabine or NS19504, respectively reduced arterial contractility to a similar degree. Further, IBTX increased both the contractile effect of XE991 and the anticontractile effect of retigabine, whereas NS19504 reduced the effect of retigabine and impaired the effect of XE991. In vessels of young rats, inhibition of Kv7 channels by XE991 enhanced arterial contractility much stronger than inhibition of BK channels by IBTX, whereas activation of Kv7 by retigabine reduced arterial contractility to a greater extent than activation of BK channels by NS19504. Further, IBTX increased the anticontractile effect of retigabine but not the contractile effect of XE991, whereas NS19504 reduced the effect of retigabine and impaired the effect of XE991. Conclusion Kv7 and BK channels are expressed in young and adult rat arteries and function as negative feedback modulators in the regulation of contractility of these arteries. Importantly, BK channels govern the extent of functional impact of Kv7 channels. This effect depends on the relationship between the functional activities of BK and Kv7 channels.
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Affiliation(s)
- Dongyu Ma
- European Center for Angioscience (ECAS), Research Division Cardiovascular Physiology, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany.,Department of Cardiology, The First Affiliated Hospital of Anhui Medical University, Anhui, China
| | - Dina Gaynullina
- European Center for Angioscience (ECAS), Research Division Cardiovascular Physiology, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany.,Faculty of Biology, M.V. Lomonosov Moscow State University, Moscow, Russia
| | - Nadine Schmidt
- European Center for Angioscience (ECAS), Research Division Cardiovascular Physiology, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Mitko Mladenov
- Department of Fundamental and Applied Physiology, Russian National Research Medical University, Moscow, Russia.,Institute of Biology, Faculty of Natural Sciences and Mathematics, Ss Cyril and Methodius University, Skopje, Macedonia
| | - Rudolf Schubert
- European Center for Angioscience (ECAS), Research Division Cardiovascular Physiology, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany.,Department of Physiology, Institute of Theoretical Medicine, Medical Faculty, University of Augsburg, Augsburg, Germany
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10
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Li T, Wu K, Yue Z, Wang Y, Zhang F, Shen H. Structural Basis for the Modulation of Human KCNQ4 by Small-Molecule Drugs. Mol Cell 2020; 81:25-37.e4. [PMID: 33238160 DOI: 10.1016/j.molcel.2020.10.037] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Revised: 09/28/2020] [Accepted: 10/28/2020] [Indexed: 12/17/2022]
Abstract
Among the five KCNQ channels, also known as the Kv7 voltage-gated potassium (Kv) channels, KCNQ2-KCNQ5 control neuronal excitability. Dysfunctions of KCNQ2-KCNQ5 are associated with neurological disorders such as epilepsy, deafness, and neuropathic pain. Here, we report the cryoelectron microscopy (cryo-EM) structures of human KCNQ4 and its complexes with the opener retigabine or the blocker linopirdine at overall resolutions of 2.5, 3.1, and 3.3 Å, respectively. In all structures, a phosphatidylinositol 4,5-bisphosphate (PIP2) molecule inserts its head group into a cavity within each voltage-sensing domain (VSD), revealing an unobserved binding mode for PIP2. Retigabine nestles in each fenestration, inducing local shifts. Instead of staying within the central pore, linopirdine resides in a cytosolic cavity underneath the inner gate. Electrophysiological analyses of various mutants corroborated the structural observations. Our studies reveal the molecular basis for the modulatory mechanism of neuronal KCNQ channels and provide a framework for structure-facilitated drug discovery targeting these important channels.
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Affiliation(s)
- Tian Li
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310024, China; Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang 310024, China; Institute of Biology, Westlake Institute for Advanced Study, Hangzhou, Zhejiang 310024, China
| | - Kun Wu
- Emergency Medicine Clinical Research Center, Beijing Key Laboratory of Cardiopulmonary Cerebral Resuscitation, Medical Research Center, Beijing Chao-Yang Hospital, Capital Medical University, Beijing 100020, China
| | - Zhenlei Yue
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310024, China; Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang 310024, China; Institute of Biology, Westlake Institute for Advanced Study, Hangzhou, Zhejiang 310024, China
| | - Yifei Wang
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310024, China; Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang 310024, China; Institute of Biology, Westlake Institute for Advanced Study, Hangzhou, Zhejiang 310024, China
| | - Fan Zhang
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310024, China; Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang 310024, China; Institute of Biology, Westlake Institute for Advanced Study, Hangzhou, Zhejiang 310024, China
| | - Huaizong Shen
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310024, China; Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang 310024, China; Institute of Biology, Westlake Institute for Advanced Study, Hangzhou, Zhejiang 310024, China.
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11
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Wray S, Arrowsmith S. Uterine Excitability and Ion Channels and Their Changes with Gestation and Hormonal Environment. Annu Rev Physiol 2020; 83:331-357. [PMID: 33158376 DOI: 10.1146/annurev-physiol-032420-035509] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We address advances in the understanding of myometrial physiology, focusing on excitation and the effects of gestation on ion channels and their relevance to labor. This review moves through pioneering studies to exciting new findings. We begin with the myometrium and its myocytes and describe how excitation might initiate and spread in this myogenic smooth muscle. We then review each of the ion channels in the myometrium: L- and T-type Ca2+ channels, KATP (Kir6) channels, voltage-dependent K channels (Kv4, Kv7, and Kv11), twin-pore domain K channels (TASK, TREK), inward rectifier Kir7.1, Ca2+-activated K+ channels with large (KCNMA1, Slo1), small (KCNN1-3), and intermediate (KCNN4) conductance, Na-activated K channels (Slo2), voltage-gated (SCN) Na+ and Na+ leak channels, nonselective (NALCN) channels, the Na K-ATPase, and hyperpolarization-activated cation channels. We finish by assessing how three key hormones- oxytocin, estrogen, and progesterone-modulate and integrate excitability throughout gestation.
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Affiliation(s)
- Susan Wray
- Department of Women's and Children's Health, University of Liverpool, Liverpool L69 3BX, United Kingdom;
| | - Sarah Arrowsmith
- Department of Women's and Children's Health, University of Liverpool, Liverpool L69 3BX, United Kingdom;
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12
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Malysz J, Petkov GV. Detrusor Smooth Muscle K V7 Channels: Emerging New Regulators of Urinary Bladder Function. Front Physiol 2020; 11:1004. [PMID: 33041840 PMCID: PMC7526500 DOI: 10.3389/fphys.2020.01004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Accepted: 07/23/2020] [Indexed: 01/21/2023] Open
Abstract
Relaxation and contraction of the urinary bladder smooth muscle, also known as the detrusor smooth muscle (DSM), facilitate the micturition cycle. DSM contractility depends on cell excitability, which is established by the synchronized activity of multiple diverse ion channels. K+ channels, the largest family of channels, control DSM excitability by maintaining the resting membrane potential and shaping the action potentials that cause the phasic contractions. Among the members of the voltage-gated K+ (KV) channel superfamily, KV type 7 (KV7) channels - KV7.1-KV7.5 members encoded by KCNQ1-KCNQ5 genes - have been recently identified as functional regulators in various cell types including vascular, cardiac, and neuronal cells. Their regulatory roles in DSM, however, are just now emerging and remain to be elucidated. To address this gap, our research group has initiated the systematic investigation of human DSM KV7 channels in collaboration with clinical urologists. In this comprehensive review, we summarize the current understanding of DSM Kv7 channels and highlight recent discoveries in the field. We describe KV7 channel expression profiles at the mRNA and protein levels, and further elaborate on functional effects of KV7 channel selective modulators on DSM excitability, contractility, and intracellular Ca2+ dynamics in animal species along with in vivo studies and the limited data on human DSM. Within each topic, we highlight the main observations, current gaps in knowledge, and most pressing questions and concepts in need of resolution. We emphasize the lack of systematic studies on human DSM KV7 channels that are now actively ongoing in our laboratory.
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Affiliation(s)
- John Malysz
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, Memphis, TN, United States
| | - Georgi V. Petkov
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, Memphis, TN, United States
- Department of Pharmacology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, United States
- Department of Urology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, United States
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13
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Serrano-Novillo C, Oliveras A, Ferreres JC, Condom E, Felipe A. Remodeling of Kv7.1 and Kv7.5 Expression in Vascular Tumors. Int J Mol Sci 2020; 21:ijms21176019. [PMID: 32825637 PMCID: PMC7503939 DOI: 10.3390/ijms21176019] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 08/11/2020] [Accepted: 08/18/2020] [Indexed: 12/16/2022] Open
Abstract
Voltage-dependent potassium (Kv) channels contribute to the excitability of nerves and muscles. In addition, Kv participates in several cell functions, including cell cycle progression and proliferation. Kv channel remodeling has been associated with neoplastic cell growth and cancer. Kv7 channels are expressed in blood vessels, and they participate in the maintenance of vascular tone and are implicated in myocyte proliferation. Although evidence links Kv7 remodeling to different types of cancer, its expression in vascular tumors has never been studied. Endothelium-derived vascular neoplasms range from indolent lesions to highly aggressive and metastasizing cancers. Here, we show that Kv7.1 and Kv7.5 are evenly distributed in tunicas as well as the endothelium of healthy veins and arteries. The layered structure of vessels is lost in vascular tumors. By studying eight vascular tumors with different origins and characteristics, we found that Kv7.1 and Kv7.5 expression was changed in vascular cancers. While both channels were generally downregulated, Kv7.5 expression was clearly correlated with neoplastic malignancy. The vascular tumors did not contract; therefore, the role of Kv7 channels is probably related to proliferation rather than controlling vascular tone. Our results identify vascular Kv7 channels as targets for cancer detection and anticancer therapies.
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Affiliation(s)
- Clara Serrano-Novillo
- Molecular Physiology Laboratory, Department de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, 08028 Barcelona, Spain; (C.S.-N.); (A.O.)
| | - Anna Oliveras
- Molecular Physiology Laboratory, Department de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, 08028 Barcelona, Spain; (C.S.-N.); (A.O.)
| | - Joan Carles Ferreres
- Consorci Corporació Sanitària Parc Taulí-Parc Taulí Hospital Universitari, Universitat Autónoma de Barcelona, 08208 Sabadell, Spain;
| | - Enric Condom
- Institut d’Investigació Biomèdica de Bellvitge (IDIBELL), Hospital Universitari de Bellvitge, 08907 L’Hospitalet de Llobregat, Spain;
| | - Antonio Felipe
- Molecular Physiology Laboratory, Department de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, 08028 Barcelona, Spain; (C.S.-N.); (A.O.)
- Departament de Bioquímica i Biomedicina Molecular, Universitat de Barcelona, Avda. Diagonal 643, 08028 Barcelona, Spain
- Correspondence: ; Tel.: +34-934034616; Fax: +34-934021559
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14
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Manoury B, Idres S, Leblais V, Fischmeister R. Ion channels as effectors of cyclic nucleotide pathways: Functional relevance for arterial tone regulation. Pharmacol Ther 2020; 209:107499. [PMID: 32068004 DOI: 10.1016/j.pharmthera.2020.107499] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2018] [Accepted: 02/05/2020] [Indexed: 02/07/2023]
Abstract
Numerous mediators and drugs regulate blood flow or arterial pressure by acting on vascular tone, involving cyclic nucleotide intracellular pathways. These signals lead to regulation of several cellular effectors, including ion channels that tune cell membrane potential, Ca2+ influx and vascular tone. The characterization of these vasocontrictive or vasodilating mechanisms has grown in complexity due to i) the variety of ion channels that are expressed in both vascular endothelial and smooth muscle cells, ii) the heterogeneity of responses among the various vascular beds, and iii) the number of molecular mechanisms involved in cyclic nucleotide signalling in health and disease. This review synthesizes key data from literature that highlight ion channels as physiologically relevant effectors of cyclic nucleotide pathways in the vasculature, including the characterization of the molecular mechanisms involved. In smooth muscle cells, cation influx or chloride efflux through ion channels are associated with vasoconstriction, whereas K+ efflux repolarizes the cell membrane potential and mediates vasodilatation. Both categories of ion currents are under the influence of cAMP and cGMP pathways. Evidence that some ion channels are influenced by CN signalling in endothelial cells will also be presented. Emphasis will also be put on recent data touching a variety of determinants such as phosphodiesterases, EPAC and kinase anchoring, that complicate or even challenge former paradigms.
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Affiliation(s)
- Boris Manoury
- Inserm, Umr-S 1180, Université Paris-Saclay, Châtenay-Malabry, France.
| | - Sarah Idres
- Inserm, Umr-S 1180, Université Paris-Saclay, Châtenay-Malabry, France
| | - Véronique Leblais
- Inserm, Umr-S 1180, Université Paris-Saclay, Châtenay-Malabry, France
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15
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Corydon KK, Matchkov V, Fais R, Abramochkin D, Hedegaard ER, Comerma-Steffensen S, Simonsen U. Effect of ischemic preconditioning and a Kv7 channel blocker on cardiac ischemia-reperfusion injury in rats. Eur J Pharmacol 2019; 866:172820. [PMID: 31760069 DOI: 10.1016/j.ejphar.2019.172820] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 11/19/2019] [Accepted: 11/20/2019] [Indexed: 12/30/2022]
Abstract
Recently, we found cardioprotective effects of ischemic preconditioning (IPC), and from a blocker of KCNQ voltage-gated K+ channels (KV7), XE991 (10,10-bis(4-pyridinylmethyl)-9(10H)-anthracenone), in isolated rat hearts. The purpose of the present study was to investigate the cardiovascular effects of IPC and XE991 and whether they are cardioprotective in intact rats. In conscious rats, we measured the effect of the KV7 channel blocker XE991 on heart rate and blood pressure by use of telemetry. In anesthetized rats, cardiac ischemia was induced by occluding the left coronary artery, and the animals received IPC (2 × 5 min of occlusion), XE991, or a combination. After a 2 h reperfusion period, the hearts were excised, and the area at risk and infarct size were determined. In both anesthetized and conscious rats, XE991 increased blood pressure, and the highest dose (7.5 mg/kg) of XE991 also increased heart rate, and 44% of conscious rats died. XE991 induced marked changes in the electrocardiogram (e.g., increased PR interval and prolonged QTC interval) without changing cardiac action potentials. The infarct size to area at risk ratio was reduced from 53 ± 2% (n = 8) in the vehicle compared to 36 ± 3% in the IPC group (P < 0.05, n = 9). XE991 (0.75 mg/kg) treatment alone or on top of IPC failed to reduce myocardial infarct size. Similar to the effect in isolated hearts, locally applied IPC was cardioprotective in intact animals exposed to ischemia-reperfusion. Systemic administration of XE991 failed to protect the heart against ischemia-reperfusion injury suggesting effects on the autonomic nervous system counteracting the cardioprotection in intact animals.
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Affiliation(s)
- Krestine Kjeldsen Corydon
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology and Physiology, Aarhus University, Wilhelm Meyers Allé 4, 8000, Aarhus C, Denmark
| | - Vladimir Matchkov
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology and Physiology, Aarhus University, Wilhelm Meyers Allé 4, 8000, Aarhus C, Denmark
| | - Rafael Fais
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology and Physiology, Aarhus University, Wilhelm Meyers Allé 4, 8000, Aarhus C, Denmark; Department of Pharmacology, Ribeirao Preto Medical School, University of Sao Paulo, Ribeirao Preto, São Paulo, Brazil
| | - Denis Abramochkin
- Department of Human and Animal Physiology, Biological Faculty, Lomonosov Moscow State University, Leninskiye Gory, 1, 12, Moscow, Russia; Ural Federal University, Mira 19, Ekaterinburg, Russia; Department of Physiology, Russian National Research Medical University, Ostrovityanova 1, Moscow, Russia
| | - Elise Røge Hedegaard
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology and Physiology, Aarhus University, Wilhelm Meyers Allé 4, 8000, Aarhus C, Denmark
| | - Simon Comerma-Steffensen
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology and Physiology, Aarhus University, Wilhelm Meyers Allé 4, 8000, Aarhus C, Denmark; Department of Biomedical Sciences/Animal Physiology, Veterinary Faculty, Central University of Venezuela, Maracay, Aragua, Venezuela
| | - Ulf Simonsen
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology and Physiology, Aarhus University, Wilhelm Meyers Allé 4, 8000, Aarhus C, Denmark.
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16
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Shvetsova AA, Gaynullina DK, Tarasova OS, Schubert R. Negative feedback regulation of vasocontraction by potassium channels in 10- to 15-day-old rats: Dominating role of K v 7 channels. Acta Physiol (Oxf) 2019; 225:e13176. [PMID: 30136434 DOI: 10.1111/apha.13176] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Revised: 08/11/2018] [Accepted: 08/20/2018] [Indexed: 12/26/2022]
Abstract
AIM Potassium channels are key regulators of smooth muscle membrane potential and arterial tone. However, the roles of potassium channels in vascular tone regulation in the systemic circulation during early postnatal development are poorly understood. Therefore, this study tested the hypothesis that the negative feedback regulation of vasocontraction by potassium channels changes during maturation. METHODS Experiments were performed on endothelium-denuded saphenous arteries from 10- to 15-day-old and 2- to 3-month-old male rats. Isometric force and membrane potential were recorded using wire myography and the sharp microelectrode technique respectively; mRNA and protein contents were determined by qPCR and Western blotting. RESULTS The effects of Kv 1, Kir and Kv 7 channel blockers (DPO-1, BaCl2 , XE991) on methoxamine-induced contraction were larger in arteries of 10- to 15-day-old compared to 2- to 3-month-old animals. In contrast, the BKC a channel blocker iberiotoxin had a stronger influence in 2- to 3- month-old rats. The effects of KATP and Kv 2 channel blockers (glibenclamide, stromatoxin) were not pronounced at both ages. The larger influence of Kv 7 and Kir channel blockade on arterial contraction in 10- to 15-day-old rats was associated with more prominent smooth muscle depolarization. The developmental alterations in potassium channel functioning were generally consistent with their mRNA and protein expression levels in arterial smooth muscle. CONCLUSION The negative feedback regulation of vasocontraction by potassium channels varies during maturation depending on the channel type. A dominating contribution of Kv 7 channels to the regulation of basal tone and agonist-induced contraction was observed in arteries of 10- to 15-day-old animals.
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Affiliation(s)
- Anastasia A. Shvetsova
- Centre for Biomedicine and Medical Technology Mannheim (CBTM); European Center of Angioscience (ECAS); Research Division Cardiovascular Physiology; Medical Faculty Mannheim; Heidelberg University; Heidelberg Germany
- Faculty of Biology; M.V. Lomonosov Moscow State University; Moscow Russia
- State Research Center of the Russian Federation - Institute for Biomedical Problems; Russian Academy of Sciences; Moscow Russia
| | - Dina K. Gaynullina
- Faculty of Biology; M.V. Lomonosov Moscow State University; Moscow Russia
- State Research Center of the Russian Federation - Institute for Biomedical Problems; Russian Academy of Sciences; Moscow Russia
- Department of Physiology; Russian National Research Medical University; Moscow Russia
| | - Olga S. Tarasova
- Faculty of Biology; M.V. Lomonosov Moscow State University; Moscow Russia
- State Research Center of the Russian Federation - Institute for Biomedical Problems; Russian Academy of Sciences; Moscow Russia
| | - Rudolf Schubert
- Centre for Biomedicine and Medical Technology Mannheim (CBTM); European Center of Angioscience (ECAS); Research Division Cardiovascular Physiology; Medical Faculty Mannheim; Heidelberg University; Heidelberg Germany
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17
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Gollasch M, Welsh DG, Schubert R. Perivascular adipose tissue and the dynamic regulation of K v 7 and K ir channels: Implications for resistant hypertension. Microcirculation 2018; 25. [PMID: 29211322 DOI: 10.1111/micc.12434] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Accepted: 11/30/2017] [Indexed: 12/20/2022]
Abstract
Resistant hypertension is defined as high blood pressure that remains uncontrolled despite treatment with at least three antihypertensive drugs at adequate doses. Resistant hypertension is an increasingly common clinical problem in older age, obesity, diabetes, sleep apnea, and chronic kidney disease. Although the direct vasodilator minoxidil was introduced in the early 1970s, only recently has this drug been shown to be particularly effective in a subgroup of patients with treatment-resistant or uncontrolled hypertension. This pharmacological approach is interesting from a mechanistic perspective as minoxidil is the only clinically used K+ channel opener today, which targets a subclass of K+ channels, namely KATP channels in VSMCs. Beside KATP channels, two other classes of VSMC K+ channels could represent novel effective targets for treatment of resistant hypertension, namely Kv 7 (KCNQ) and inward rectifier potassium (Kir 2.1) channels. Interestingly, these channels are unique among VSMC potassium channels. First, both have been implicated in the control of microvascular tone by perivascular adipose tissue. Second, they exhibit biophysical properties strongly controlled and regulated by membrane voltage, but not intracellular calcium. This review focuses on Kv 7 (Kv 7.1-5) and Kir (Kir 2.1) channels in VSMCs as potential novel drug targets for treatment of resistant hypertension, particularly in comorbid conditions such as obesity and metabolic syndrome.
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Affiliation(s)
- Maik Gollasch
- Medical Clinic for Nephrology and Internal Intensive Care, Charité Campus Virchow Klinikum, Experimental and Clinical Research Center (ECRC) - a joint cooperation between the Charité - University Medicine Berlin and the Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany
| | - Donald G Welsh
- Department of Physiology and Pharmacology, Western University, London, ON, Canada
| | - Rudolf Schubert
- Centre for Biomedicine and Medical Technology Mannheim (CBTM), Research Division Cardiovascular Physiology, Medical Faculty Mannheim, Heidelberg University, Heidelberg, Germany
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18
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Mahapatra C, Brain KL, Manchanda R. A biophysically constrained computational model of the action potential of mouse urinary bladder smooth muscle. PLoS One 2018; 13:e0200712. [PMID: 30048468 PMCID: PMC6061979 DOI: 10.1371/journal.pone.0200712] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Accepted: 07/02/2018] [Indexed: 11/19/2022] Open
Abstract
Urinary incontinence is associated with enhanced spontaneous phasic contractions of the detrusor smooth muscle (DSM). Although a complete understanding of the etiology of these spontaneous contractions is not yet established, it is suggested that the spontaneously evoked action potentials (sAPs) in DSM cells initiate and modulate the contractions. In order to further our understanding of the ionic mechanisms underlying sAP generation, we present here a biophysically detailed computational model of a single DSM cell. First, we constructed mathematical models for nine ion channels found in DSM cells based on published experimental data: two voltage gated Ca2+ ion channels, an hyperpolarization-activated ion channel, two voltage-gated K+ ion channels, three Ca2+-activated K+ ion channels and a non-specific background leak ion channel. The ion channels' kinetics were characterized in terms of maximal conductances and differential equations based on voltage or calcium-dependent activation and inactivation. All ion channel models were validated by comparing the simulated currents and current-voltage relations with those reported in experimental work. Incorporating these channels, our DSM model is capable of reproducing experimentally recorded spike-type sAPs of varying configurations, ranging from sAPs displaying after-hyperpolarizations to sAPs displaying after-depolarizations. The contributions of the principal ion channels to spike generation and configuration were also investigated as a means of mimicking the effects of selected pharmacological agents on DSM cell excitability. Additionally, the features of propagation of an AP along a length of electrically continuous smooth muscle tissue were investigated. To date, a biophysically detailed computational model does not exist for DSM cells. Our model, constrained heavily by physiological data, provides a powerful tool to investigate the ionic mechanisms underlying the genesis of DSM electrical activity, which can further shed light on certain aspects of urinary bladder function and dysfunction.
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Affiliation(s)
- Chitaranjan Mahapatra
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai, Maharashtra, India
| | - Keith L. Brain
- School of Clinical and Experimental Medicine, University of Birmingham, Birmingham, England, United Kingdom
| | - Rohit Manchanda
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai, Maharashtra, India
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19
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Wei X, Zhang Y, Yin B, Wen J, Cheng J, Fu X. The expression and function of KCNQ potassium channels in human chorionic plate arteries from women with normal pregnancies and pre-eclampsia. PLoS One 2018; 13:e0192122. [PMID: 29579054 PMCID: PMC5868761 DOI: 10.1371/journal.pone.0192122] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Accepted: 01/18/2018] [Indexed: 11/25/2022] Open
Abstract
Pre-eclampsia is associated with altered maternal and placental vascular reactivity. Kv7 channels (encoded by KCNQ 1–5 genes) are a potential contributor to the regulation of vascular tone in CPAs (chorionic plate arteries) during normal pregnancy. The aim of this study is to establish the expression profile of KCNQ subunits in CPAs taken from women with preeclampsia or normotensive women and to examine the functional relevance of the Kv7 channels on an altered expression profile of KCNQ subunits. The effects of Kv7 channel modulators on CPAs were investigated by tension measurement. Quantitative PCR experiments were used to analyze the expression of KCNQ genes. Western blotting and immunofluorescence were both used to analyze the protein expression of Kv7 channels. Finally, in CPAs from normotensive women, the Kv7 channel blocker XE991 increased arterial basal tone and U46619-induced contraction, and pre-contracted CPAs (10−7 M U46619) exhibited significant relaxation following treatment with Retigabine(Kv7.2–7.5 activator) and BMS-204352(Kv7.2–7.5 activator). However, ICA-27243(selective KCNQ2 and KCNQ3 activator) and ML277(selective KV7.1 activator) had no significant effect on tension in the pre-contracted CPAs. Conversely, compared with CPAs from normotensive women, the effects of XE991 on basal tone and agonist (U46619)-induced contractions in CPAs from women with preeclampsia were markedly attenuated. Moreover, the relaxation effects of Retigabine and BMS-204352 on pre-contracted CPA vessels from women with pre-eclampsia were also markedly down-regulated. Interestingly, the relaxation ability of ICA-27243 in pre-contracted CPA vessels in women with pre-eclampsia was enhanced. The mRNA of KCNQ3 was specifically up-regulated, whereas those for KCNQ4 and KCNQ5 were down-regulated in CPAs from women with pre-eclampsia compared with those in normotensive women. Similar observations were found in a subsequent analysis of protein expression of KCNQ genes 3–5. Thus, down-regulated Kv7 channel function in tension regulation of CPAs in women with pre-eclampsia could be associated with considerably altered expression profiles of Kv7 subunits.
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Affiliation(s)
- Xiaohong Wei
- Department of Gynecology and Obstetrics, the Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan, China
| | - Yujiao Zhang
- Department of Gynecology and Obstetrics, the Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan, China
| | - Benlan Yin
- Department of Gynecology and Obstetrics, the Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan, China
| | - Jing Wen
- Key Laboratory of Medical Electrophysiology of Ministry of Education, Collaborative Innovation Center for Prevention and Treatment of Cardiovascular Research, Southwest Medical University, Luzhou, Sichuan, China
| | - Jun Cheng
- Key Laboratory of Medical Electrophysiology of Ministry of Education, Collaborative Innovation Center for Prevention and Treatment of Cardiovascular Research, Southwest Medical University, Luzhou, Sichuan, China
| | - Xiaodong Fu
- Department of Gynecology and Obstetrics, the Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan, China
- * E-mail:
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20
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Khammy MM, Kim S, Bentzen BH, Lee S, Choi I, Aalkjaer C, Jepps TA. 4-Aminopyridine: a pan voltage-gated potassium channel inhibitor that enhances K v 7.4 currents and inhibits noradrenaline-mediated contraction of rat mesenteric small arteries. Br J Pharmacol 2018; 175:501-516. [PMID: 29156097 DOI: 10.1111/bph.14097] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 11/01/2017] [Accepted: 11/08/2017] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND AND PURPOSE Kv 7.4 and Kv 7.5 channels are regulators of vascular tone. 4-Aminopyridine (4-AP) is considered a broad inhibitor of voltage-gated potassium (KV ) channels, with little inhibitory effect on Kv 7 family members at mmol concentrations. However, the effect of 4-AP on Kv 7 channels has not been systematically studied. The aim of this study was to investigate the pharmacological activity of 4-AP on Kv 7.4 and Kv 7.5 channels and characterize the effect of 4-AP on rat resistance arteries. EXPERIMENTAL APPROACH Voltage clamp experiments were performed on Xenopus laevis oocytes injected with cRNA encoding KCNQ4 or KCNQ5, HEK cells expressing Kv 7.4 channels and on rat, freshly isolated mesenteric artery smooth muscle cells. The effect of 4-AP on tension, membrane potential, intracellular calcium and pH was assessed in rat mesenteric artery segments. KEY RESULTS 4-AP increased the Kv 7.4-mediated current in oocytes and HEK cells but did not affect Kv 7.5 current. 4-AP also enhanced native mesenteric artery myocyte K+ current at sub-mmol concentrations. When applied to NA-preconstricted mesenteric artery segments, 4-AP hyperpolarized the membrane, decreased [Ca2+ ]i and caused concentration-dependent relaxations that were independent of 4-AP-mediated changes in intracellular pH. Application of the Kv 7 channel blocker XE991 and BKCa channel blocker iberiotoxin attenuated 4-AP-mediated relaxation. 4-AP also inhibited the NA-mediated signal transduction to elicit a relaxation. CONCLUSIONS AND IMPLICATIONS These data show that 4-AP is able to relax NA-preconstricted rat mesenteric arteries by enhancing the activity of Kv 7.4 and BKCa channels and attenuating NA-mediated signalling.
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Affiliation(s)
- Makhala M Khammy
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Sukhan Kim
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Bo H Bentzen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Soojung Lee
- Department of Physiology, Emory University School of Medicine, Atlanta, GA, USA
| | - Inyeong Choi
- Department of Physiology, Emory University School of Medicine, Atlanta, GA, USA
| | - Christian Aalkjaer
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Thomas A Jepps
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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21
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Liñán-Rico A, Ochoa-Cortes F, Zuleta-Alarcon A, Alhaj M, Tili E, Enneking J, Harzman A, Grants I, Bergese S, Christofi FL. UTP - Gated Signaling Pathways of 5-HT Release from BON Cells as a Model of Human Enterochromaffin Cells. Front Pharmacol 2017; 8:429. [PMID: 28751862 PMCID: PMC5508028 DOI: 10.3389/fphar.2017.00429] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 06/15/2017] [Indexed: 12/30/2022] Open
Abstract
Background: Enterochromaffin cells (EC) synthesize and release 5-HT and ATP to trigger or modulate gut neural reflexes and transmit information about visceral/pain sensation. Alterations in 5-HT signaling mechanisms may contribute to the pathogenesis of IBD or IBS, but the pharmacologic or molecular mechanisms modulating Ca2+-dependent 5-HT release are not understood. Previous studies indicated that purinergic signaling via ATP and ADP is an important mechanism in modulation of 5-HT release. However, EC cells also respond to UTP and UDP suggesting uridine triphosphate receptor and signaling pathways are involved as well. We tested the hypothesis that UTP is a regulator of 5-HT release in human EC cells. Methods: UTP signaling mechanisms were studied in BON cells, a human EC model, using Fluo-4/Ca2+imaging, patch-clamp, pharmacological analysis, immunohistochemistry, western blots and qPCR. 5-HT release was monitored in BON or EC isolated from human gut surgical specimens (hEC). Results: UTP, UTPγS, UDP or ATP induced Ca2+oscillations in BON. UTP evoked a biphasic concentration-dependent Ca2+response. Cells responded in the order of UTP, ATP > UTPγS > UDP >> MRS2768, BzATP, α,β-MeATP > MRS2365, MRS2690, and NF546. Different proportions of cells activated by UTP and ATP also responded to UTPγS (P2Y4, 50% cells), UDP (P2Y6, 30%), UTPγS and UDP (14%) or MRS2768 (<3%). UTP Ca2+responses were blocked with inhibitors of PLC, IP3R, SERCA Ca2+pump, La3+sensitive Ca2+channels or chelation of intracellular free Ca2+ by BAPTA/AM. Inhibitors of L-type, TRPC, ryanodine-Ca2+pools, PI3-Kinase, PKC or SRC-Kinase had no effect. UTP stimulated voltage-sensitive Ca2+currents (ICa), Vm-depolarization and inhibited IK (not IA) currents. An IKv7.2/7.3 K+ channel blocker XE-991 mimicked UTP-induced Vm-depolarization and blocked UTP-responses. XE-991 blocked IK and UTP caused further reduction. La3+ or PLC inhibitors blocked UTP depolarization; PKC inhibitors, thapsigargin or zero Ca2+buffer did not. UTP stimulated 5-HT release in hEC expressing TPH1, 5-HT, P2Y4/P2Y6R. Zero-Ca2+buffer augmented Ca2+responses and 5-HT release. Conclusion: UTP activates a predominant P2Y4R pathway to trigger Ca2+oscillations via internal Ca2+mobilization through a PLC/IP3/IP3R/SERCA Ca2+signaling pathway to stimulate 5-HT release; Ca2+influx is inhibitory. UTP-induced Vm-depolarization depends on PLC signaling and an unidentified K channel (which appears independent of Ca2+oscillations or Ica/VOCC). UTP-gated signaling pathways triggered by activation of P2Y4R stimulate 5-HT release.
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Affiliation(s)
- Andromeda Liñán-Rico
- Department of Anesthesiology, The Wexner Medical Center at The Ohio State University, ColumbusOH, United States
| | - Fernando Ochoa-Cortes
- Department of Anesthesiology, The Wexner Medical Center at The Ohio State University, ColumbusOH, United States
| | - Alix Zuleta-Alarcon
- Department of Anesthesiology, The Wexner Medical Center at The Ohio State University, ColumbusOH, United States
| | - Mazin Alhaj
- Department of Anesthesiology, The Wexner Medical Center at The Ohio State University, ColumbusOH, United States
| | - Esmerina Tili
- Department of Anesthesiology, The Wexner Medical Center at The Ohio State University, ColumbusOH, United States
- Molecular Virology, Immunology and Medical Genetics, The Wexner Medical Center at The Ohio State University, ColumbusOH, United States
| | - Josh Enneking
- Department of Anesthesiology, The Wexner Medical Center at The Ohio State University, ColumbusOH, United States
| | - Alan Harzman
- Department of Surgery, The Wexner Medical Center at The Ohio State University, ColumbusOH, United States
| | - Iveta Grants
- Department of Anesthesiology, The Wexner Medical Center at The Ohio State University, ColumbusOH, United States
| | - Sergio Bergese
- Department of Anesthesiology, The Wexner Medical Center at The Ohio State University, ColumbusOH, United States
| | - Fievos L. Christofi
- Department of Anesthesiology, The Wexner Medical Center at The Ohio State University, ColumbusOH, United States
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22
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Beltrán LR, Dawid C, Beltrán M, Levermann J, Titt S, Thomas S, Pürschel V, Satalik M, Gisselmann G, Hofmann T, Hatt H. The Effect of Pungent and Tingling Compounds from Piper nigrum L. on Background K + Currents. Front Pharmacol 2017; 8:408. [PMID: 28694780 PMCID: PMC5483439 DOI: 10.3389/fphar.2017.00408] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Accepted: 06/08/2017] [Indexed: 12/20/2022] Open
Abstract
Black peppercorns (Piper nigrum L.) elicit a pungent and tingling oral impression. Their pungency is partially explained by the agonist activity of some of their active principles, especially piperine, on TRP channels. However, we recently showed that piperine, as well as other pungent compounds, also possess a marked effect on two-pore domain (KCNK, K2P) K+ channels. Members of this family play a key role in maintaining the resting membrane potential of excitable cells. Interestingly, tingling compounds have been shown to induce neuronal excitation by inhibiting KCNK channels. We addressed the question of whether it was plausible that KCNK channels could constitute a physiologically relevant target for the sensory active compounds present in black peppercorns. Because previous studies have demonstrated that mouse trigeminal neurons respond to several pungent compounds, to which humans are also sensitive, we used a primary culture of mouse trigeminal neurons to investigate whether the effect of piperine on these cell types could also be mediated by KCNK channels. We observed that even in the presence of classical TRP-antagonists, piperine was still able to activate a fraction of trigeminal neurons. Furthermore, our results showed that piperine is capable of inducing neuronal depolarization by a mechanism that does not require extracellular Na+ or Ca2+. This depolarization was mediated by the inhibition of a background K+ conductance, most likely corresponding to the KCNK channels of the TASK subfamily. We then performed a screening with 12 other pungent and/or tingling chemosensates isolated from black peppercorns. These compounds were evaluated on Xenopus laevis oocytes expressing the human orthologues of KCNK3, KNCK9 and KCNK18, which we previously showed to be inhibited by piperine. Remarkably, almost all of the isolated chemosensates inhibited the basal activity of hKCNK3, with 1-(octadeca-2E,4E,13/12Z-trienoyl)pyrrolidine acting as one of the most potent natural blockers for hKCNK3 found to date. Our results suggest that KCNK channels, especially KCNK3, are likely to play a complementary role to TRP channels in the complex orosensory impression elicited by black peppercorns, while they also help to expand the pharmacological knowledge of KCNK channels.
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Affiliation(s)
| | - Corinna Dawid
- Chair of Food Chemistry and Molecular Sensory Science, Technische Universität MünchenFreising, Germany
| | - Madeline Beltrán
- Department of Receptor Biochemistry, Ruhr-University-BochumBochum, Germany
| | - Janina Levermann
- Department of Cell Physiology, Ruhr-University-BochumBochum, Germany
| | - Sascha Titt
- Department of Cell Physiology, Ruhr-University-BochumBochum, Germany
| | - Sini Thomas
- Department of Cell Physiology, Ruhr-University-BochumBochum, Germany
| | - Viktoria Pürschel
- Department of Cell Physiology, Ruhr-University-BochumBochum, Germany
| | - Miriam Satalik
- Department of Cell Physiology, Ruhr-University-BochumBochum, Germany
| | - Günter Gisselmann
- Department of Cell Physiology, Ruhr-University-BochumBochum, Germany
| | - Thomas Hofmann
- Chair of Food Chemistry and Molecular Sensory Science, Technische Universität MünchenFreising, Germany
| | - Hanns Hatt
- Department of Cell Physiology, Ruhr-University-BochumBochum, Germany
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23
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Tykocki NR, Boerman EM, Jackson WF. Smooth Muscle Ion Channels and Regulation of Vascular Tone in Resistance Arteries and Arterioles. Compr Physiol 2017; 7:485-581. [PMID: 28333380 DOI: 10.1002/cphy.c160011] [Citation(s) in RCA: 212] [Impact Index Per Article: 30.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Vascular tone of resistance arteries and arterioles determines peripheral vascular resistance, contributing to the regulation of blood pressure and blood flow to, and within the body's tissues and organs. Ion channels in the plasma membrane and endoplasmic reticulum of vascular smooth muscle cells (SMCs) in these blood vessels importantly contribute to the regulation of intracellular Ca2+ concentration, the primary determinant of SMC contractile activity and vascular tone. Ion channels provide the main source of activator Ca2+ that determines vascular tone, and strongly contribute to setting and regulating membrane potential, which, in turn, regulates the open-state-probability of voltage gated Ca2+ channels (VGCCs), the primary source of Ca2+ in resistance artery and arteriolar SMCs. Ion channel function is also modulated by vasoconstrictors and vasodilators, contributing to all aspects of the regulation of vascular tone. This review will focus on the physiology of VGCCs, voltage-gated K+ (KV) channels, large-conductance Ca2+-activated K+ (BKCa) channels, strong-inward-rectifier K+ (KIR) channels, ATP-sensitive K+ (KATP) channels, ryanodine receptors (RyRs), inositol 1,4,5-trisphosphate receptors (IP3Rs), and a variety of transient receptor potential (TRP) channels that contribute to pressure-induced myogenic tone in resistance arteries and arterioles, the modulation of the function of these ion channels by vasoconstrictors and vasodilators, their role in the functional regulation of tissue blood flow and their dysfunction in diseases such as hypertension, obesity, and diabetes. © 2017 American Physiological Society. Compr Physiol 7:485-581, 2017.
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Affiliation(s)
- Nathan R Tykocki
- Department of Pharmacology, University of Vermont, Burlington, Vermont, USA
| | - Erika M Boerman
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri, USA
| | - William F Jackson
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan, USA
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24
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Tsvetkov D, Kaßmann M, Tano JY, Chen L, Schleifenbaum J, Voelkl J, Lang F, Huang Y, Gollasch M. Do K V 7.1 channels contribute to control of arterial vascular tone? Br J Pharmacol 2016; 174:150-162. [PMID: 28000293 DOI: 10.1111/bph.13665] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Revised: 10/11/2016] [Accepted: 10/28/2016] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND AND PURPOSE KV 7.1 voltage-gated potassium channels are expressed in vascular smooth muscle cells (VSMC) of diverse arteries, including mesenteric arteries. Based on pharmacological evidence using R-L3 (KV 7.1 channel opener), HMR1556, chromanol 293B (KV 7.1 channel blockers), stimulation of these channels has been suggested to evoke profound relaxation in various vascular beds of rats. However, the specificity of these drugs in vivo is uncertain. EXPERIMENTAL APPROACH We used Kcnq1-/- mice and pharmacological tools to determine whether KV 7.1 channels play a role in the regulation of arterial tone. KEY RESULTS R-L3 produced similar concentration-dependent relaxations (EC50 ~ 1.4 μM) of arteries from wild-type (Kcnq1+/+ ) and Kcnq1-/- mice, pre-contracted with either phenylephrine or 60 mM KCl. This relaxation was not affected by 10 μM chromanol 293B, 10 μM HMR1556 or 30 μM XE991 (pan-KV 7 channel blocker). The anti-contractile effects of the perivascular adipose tissue (PVAT) were normal in Kcnq1-/- arteries. Chromanol 293B and HMR1556 did not affect the anti-contractile effects of (PVAT). Isolated VSMCs from Kcnq1-/- mice exhibited normal peak KV currents. The KV 7.2-5 channel opener retigabine caused similar relaxations in Kcnq1-/- and wild-type vessels. CONCLUSION AND IMPLICATIONS We conclude that KV 7.1 channels were apparently not involved in the control of arterial tone by α1 -adrenoceptor agonists and PVAT. In addition, R-L3 is an inappropriate pharmacological tool for studying the function of native vascular KV 7.1 channels in mice.
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Affiliation(s)
- Dmitry Tsvetkov
- Experimental and Clinical Research Center (ECRC), A Joint Cooperation between the Charité Medical Faculty and the Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany.,Department of Pharmacology and Experimental Therapy, Institute of Experimental and Clinical Pharmacology and Toxicology, Eberhard Karls University Hospitals and Clinics and Interfaculty Center of Pharmacogenomics and Drug Research, University of Tübingen, Tübingen, Germany
| | - Mario Kaßmann
- Experimental and Clinical Research Center (ECRC), A Joint Cooperation between the Charité Medical Faculty and the Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany
| | - Jean-Yves Tano
- Experimental and Clinical Research Center (ECRC), A Joint Cooperation between the Charité Medical Faculty and the Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany
| | - Lan Chen
- Experimental and Clinical Research Center (ECRC), A Joint Cooperation between the Charité Medical Faculty and the Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany.,Xiamen Zhongshan Hospital, Xiamen University, Xiamen, China
| | - Johanna Schleifenbaum
- Experimental and Clinical Research Center (ECRC), A Joint Cooperation between the Charité Medical Faculty and the Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany
| | - Jakob Voelkl
- Department of Cardiology, Vascular Medicine and Physiology, University of Tübingen, Tübingen, Germany
| | - Florian Lang
- Department of Cardiology, Vascular Medicine and Physiology, University of Tübingen, Tübingen, Germany
| | - Yu Huang
- School of Biomedical Sciences, 223A, Lo Kwee-Seong Integrated Biomedical Sciences Building, Area 39, Chinese University of Hong Kong, Sha Tin, Hong Kong
| | - Maik Gollasch
- Experimental and Clinical Research Center (ECRC), A Joint Cooperation between the Charité Medical Faculty and the Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany.,Medical Clinic for Nephrology and Internal Intensive Care, Campus Virchow, Charité University Medicine, Berlin, Germany
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25
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Zhang X, An H, Li J, Zhang Y, Liu Y, Jia Z, Zhang W, Chu L, Zhang H. Selective activation of vascular K v 7.4/K v 7.5 K + channels by fasudil contributes to its vasorelaxant effect. Br J Pharmacol 2016; 173:3480-3491. [PMID: 27677924 DOI: 10.1111/bph.13639] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2015] [Revised: 09/13/2016] [Accepted: 09/15/2016] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND AND PURPOSE Kv 7 (Kv 7.1-7.5) channels play an important role in the regulation of neuronal excitability and the cardiac action potential. Growing evidence suggests Kv 7.4/Kv 7.5 channels play a crucial role in regulating vascular smooth muscle contractility. Most of the reported Kv 7 openers have shown poor selectivity across these five subtypes. In this study, fasudil - a drug used for cerebral vasospasm - has been found to be a selective opener of Kv 7.4/Kv 7.5 channels. EXPERIMENTAL APPROACH A perforated whole-cell patch technique was used to record the currents and membrane potential. Homology modelling and a docking technique were used to investigate the interaction between fasudil and the Kv 7.4 channel. An isometric tension recording technique was used to assess the vascular tension. KEY RESULTS Fasudil selectively and potently enhanced Kv 7.4 and Kv 7.4/Kv 7.5 currents expressed in HEK293 cells, and shifted the voltage-dependent activation curve in a more negative direction. Fasudil did not affect either Kv 7.2 and Kv 7.2/Kv 7.3 currents expressed in HEK293 cells, the native neuronal M-type K+ currents, or the resting membrane potential in small rat dorsal root ganglia neurons. The Val248 in S5 and Ile308 in S6 segment of Kv 7.4 were critical for this activating effect of fasudil. Fasudil relaxed precontracted rat small arteries in a concentration-dependent fashion; this effect was antagonized by the Kv 7 channel blocker XE991. CONCLUSIONS AND IMPLICATIONS These results suggest that fasudil is a selective Kv 7.4/Kv 7.5 channel opener and provide a new dimension for developing selective Kv 7 modulators and a new prospective for the use, action and mechanism of fasudil.
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Affiliation(s)
- Xuan Zhang
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, China.,Department of Pharmacology, Hebei University of Chinese Medicine, Shijiazhuang, China.,Department of Pharmacology, Institution of Chinese Integrative Medicine, Hebei Medical University, Shijiazhuang, China
| | - Hailong An
- Key Laboratory of Molecular Biophysics, Hebei Province; Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, China
| | - Junwei Li
- Key Laboratory of Molecular Biophysics, Hebei Province; Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, China
| | - Yuanyuan Zhang
- Department of Pharmacology, Hebei University of Chinese Medicine, Shijiazhuang, China
| | - Yang Liu
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, China.,Department of Pharmacology, Hebei University of Chinese Medicine, Shijiazhuang, China
| | - Zhanfeng Jia
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, China
| | - Wei Zhang
- Department of Pharmacology, Institution of Chinese Integrative Medicine, Hebei Medical University, Shijiazhuang, China
| | - Li Chu
- Department of Pharmacology, Hebei University of Chinese Medicine, Shijiazhuang, China
| | - Hailin Zhang
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, China
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26
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KV7 channels in the human detrusor: channel modulator effects and gene and protein expression. Naunyn Schmiedebergs Arch Pharmacol 2016; 390:127-137. [DOI: 10.1007/s00210-016-1312-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Accepted: 10/11/2016] [Indexed: 12/13/2022]
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27
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Tsvetkov D, Tano JY, Kassmann M, Wang N, Schubert R, Gollasch M. The Role of DPO-1 and XE991-Sensitive Potassium Channels in Perivascular Adipose Tissue-Mediated Regulation of Vascular Tone. Front Physiol 2016; 7:335. [PMID: 27540364 PMCID: PMC4973012 DOI: 10.3389/fphys.2016.00335] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Accepted: 07/20/2016] [Indexed: 11/13/2022] Open
Abstract
The anti-contractile effect of perivascular adipose tissue (PVAT) is an important mechanism in the modulation of vascular tone in peripheral arteries. Recent evidence has implicated the XE991-sensitive voltage-gated KV (KCNQ) channels in the regulation of arterial tone by PVAT. However, until now the in vivo pharmacology of the involved vascular KV channels with regard to XE991 remains undetermined, since XE991 effects may involve Ca(2+) activated BKCa channels and/or voltage-dependent KV1.5 channels sensitive to diphenyl phosphine oxide-1 (DPO-1). In this study, we tested whether KV1.5 channels are involved in the control of mesenteric arterial tone and its regulation by PVAT. Our study was also aimed at extending our current knowledge on the in situ vascular pharmacology of DPO-1 and XE991 regarding KV1.5 and BKCa channels, in helping to identify the nature of K(+) channels that could contribute to PVAT-mediated relaxation. XE991 at 30 μM reduced the anti-contractile response of PVAT, but had no effects on vasocontraction induced by phenylephrine (PE) in the absence of PVAT. Similar effects were observed for XE991 at 0.3 μM, which is known to almost completely inhibit mesenteric artery VSMC KV currents. 30 μM XE991 did not affect BKCa currents in VSMCs. Kcna5 (-/-) arteries and wild-type arteries incubated with 1 μM DPO-1 showed normal vasocontractions in response to PE in the presence and absence of PVAT. KV current density and inhibition by 30 μM XE991 were normal in mesenteric artery VSMCs isolated from Kcna5 (-/-) mice. We conclude that KV channels are involved in the control of arterial vascular tone by PVAT. These channels are present in VSMCs and very potently inhibited by the KCNQ channel blocker XE991. BKCa channels and/or DPO-1 sensitive KV1.5 channels in VSMCs are not the downstream mediators of the XE991 effects on PVAT-dependent arterial vasorelaxation. Further studies will need to be undertaken to examine the role of other KV channels in the phenomenon.
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Affiliation(s)
- Dmitry Tsvetkov
- Experimental and Clinical Research Center, A Joint Cooperation between the Charité Medical Faculty and the Max Delbrück Center for Molecular Medicine in the Helmholtz Association of German Research Centres Berlin, Germany
| | - Jean-Yves Tano
- Experimental and Clinical Research Center, A Joint Cooperation between the Charité Medical Faculty and the Max Delbrück Center for Molecular Medicine in the Helmholtz Association of German Research Centres Berlin, Germany
| | - Mario Kassmann
- Experimental and Clinical Research Center, A Joint Cooperation between the Charité Medical Faculty and the Max Delbrück Center for Molecular Medicine in the Helmholtz Association of German Research Centres Berlin, Germany
| | - Ning Wang
- Experimental and Clinical Research Center, A Joint Cooperation between the Charité Medical Faculty and the Max Delbrück Center for Molecular Medicine in the Helmholtz Association of German Research Centres Berlin, Germany
| | - Rudolf Schubert
- Research Division Cardiovascular Physiology, Centre for Biomedicine and Medical Technology Mannheim, Medical Faculty Mannheim of the University Heidelberg Mannheim, Germany
| | - Maik Gollasch
- Experimental and Clinical Research Center, A Joint Cooperation between the Charité Medical Faculty and the Max Delbrück Center for Molecular Medicine in the Helmholtz Association of German Research CentresBerlin, Germany; Medical Clinic for Nephrology and Internal Intensive Care, Charité University MedicineBerlin, Germany
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28
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Carr G, Barrese V, Stott JB, Povstyan OV, Jepps TA, Figueiredo HB, Zheng D, Jamshidi Y, Greenwood IA. MicroRNA-153 targeting of KCNQ4 contributes to vascular dysfunction in hypertension. Cardiovasc Res 2016; 112:581-589. [PMID: 27389411 PMCID: PMC5079273 DOI: 10.1093/cvr/cvw177] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Accepted: 07/01/2016] [Indexed: 11/30/2022] Open
Abstract
Aims Kv7.4, a voltage-dependent potassium channel expressed throughout the vasculature, controls arterial contraction and is compromised in hypertension by an unknown mechanism. MicroRNAs (miRs) are post-transcriptional regulators of protein production and are altered in disease states such as hypertension. We investigated whether miRs regulate Kv7.4 expression. Methods and results In renal and mesenteric arteries (MAs) of the spontaneously hypertensive rat (SHR), Kv7.4 protein decreased compared with the normotensive (NT) rat without a decrease in KCNQ4 mRNA, inferring that Kv7.4 abundance was determined by post-transcriptional regulation. In silico analysis of the 3′ UTR of KCNQ4 revealed seed sequences for miR26a, miR133a, miR200b, miR153, miR214, miR218, and let-7d with quantitative polymerase chain reaction showing miR153 increased in those arteries from SHRs that exhibited decreased Kv7.4 levels. Luciferase reporter assays indicated a direct targeting effect of miR153 on the 3′ UTR of KCNQ4. Introduction of high levels of miR153 to MAs increased vascular wall thickening and reduced Kv7.4 expression/Kv7 channel function compared with vessels receiving a non-targeting miR, providing a proof of concept of Kv7.4 regulation by miR153. Conclusion This study is the first to define a role for aberrant miR153 contributing to the hypertensive state through targeting of KCNQ4 in an animal model of hypertension, raising the possibility of the use of miR153-related therapies in vascular disease.
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Affiliation(s)
- Georgina Carr
- Vascular Research Centre, St George's University of London, Cranmer Terrace, London SW17 0RE, UK
| | - Vincenzo Barrese
- Vascular Research Centre, St George's University of London, Cranmer Terrace, London SW17 0RE, UK
| | - Jennifer B Stott
- Vascular Research Centre, St George's University of London, Cranmer Terrace, London SW17 0RE, UK
| | - Oleksandr V Povstyan
- Vascular Research Centre, St George's University of London, Cranmer Terrace, London SW17 0RE, UK
| | - Thomas A Jepps
- Ion Channels Group, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Hericka B Figueiredo
- Vascular Research Centre, St George's University of London, Cranmer Terrace, London SW17 0RE, UK
| | - Dongling Zheng
- Vascular Research Centre, St George's University of London, Cranmer Terrace, London SW17 0RE, UK
| | - Yalda Jamshidi
- Vascular Research Centre, St George's University of London, Cranmer Terrace, London SW17 0RE, UK
| | - Iain A Greenwood
- Vascular Research Centre, St George's University of London, Cranmer Terrace, London SW17 0RE, UK.,Ion Channels Group, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
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29
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Haick JM, Byron KL. Novel treatment strategies for smooth muscle disorders: Targeting Kv7 potassium channels. Pharmacol Ther 2016; 165:14-25. [PMID: 27179745 DOI: 10.1016/j.pharmthera.2016.05.002] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Smooth muscle cells provide crucial contractile functions in visceral, vascular, and lung tissues. The contractile state of smooth muscle is largely determined by their electrical excitability, which is in turn influenced by the activity of potassium channels. The activity of potassium channels sustains smooth muscle cell membrane hyperpolarization, reducing cellular excitability and thereby promoting smooth muscle relaxation. Research over the past decade has indicated an important role for Kv7 (KCNQ) voltage-gated potassium channels in the regulation of the excitability of smooth muscle cells. Expression of multiple Kv7 channel subtypes has been demonstrated in smooth muscle cells from viscera (gastrointestinal, bladder, myometrial), from the systemic and pulmonary vasculature, and from the airways of the lung, from multiple species, including humans. A number of clinically used drugs, some of which were developed to target Kv7 channels in other tissues, have been found to exert robust effects on smooth muscle Kv7 channels. Functional studies have indicated that Kv7 channel activators and inhibitors have the ability to relax and contact smooth muscle preparations, respectively, suggesting a wide range of novel applications for the pharmacological tool set. This review summarizes recent findings regarding the physiological functions of Kv7 channels in smooth muscle, and highlights potential therapeutic applications based on pharmacological targeting of smooth muscle Kv7 channels throughout the body.
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Affiliation(s)
- Jennifer M Haick
- Department of Molecular Pharmacology & Therapeutics, Stritch School of Medicine, Loyola University Chicago, Maywood, IL, USA
| | - Kenneth L Byron
- Department of Molecular Pharmacology & Therapeutics, Stritch School of Medicine, Loyola University Chicago, Maywood, IL, USA.
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30
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Zhang Y, Chu X, Liu L, Zhang N, Guo H, Yang F, Liu Z, Dong Y, Bao Y, Zhang X, Zhang J. Tannic acid activates the Kv7.4 and Kv7.3/7.5 K+ channels expressed in HEK293 cells and reduces tension in the rat mesenteric arteries. J Pharm Pharmacol 2016; 68:494-502. [PMID: 26969140 DOI: 10.1111/jphp.12527] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Accepted: 01/14/2016] [Indexed: 12/13/2022]
Abstract
Abstract
Objectives
This study investigated the effect of tannic acid (TA), a plant-derived hydrolyzable polyphenol, on Kv7.4 and Kv7.5 K+ channels and rat mesenteric artery.
Methods
Whole-cell patch clamp experiments were used to record the Kv7.4 and Kv7.3/7.5 K+ currents expressed in HEK293 cells; and the tension changes of mesenteric arteries isolated from rats were recorded using small vessel myography apparatus.
Key findings
Tannic acid increases the Kv7.4 and Kv7.3/7.5 K+ currents in a concentration-dependent manner (median effective concentration (EC50) = 27.3 ± 3.6 μm and EC50 = 23.1 ± 3.9 μm, respectively). In addition, 30 μm TA shifts the G–V curve of Kv7.4 and Kv7.3/7.5 K+ currents to the left by 14.18 and 25.24 mV, respectively, and prolongs the deactivation time constants by 184.44 and 154.77 ms, respectively. Moreover, TA relaxes the vascular tension of rat mesenteric arteries in a concentration-dependent manner (half inhibitory concentration (IC50) = 148.7 ± 13.4 μm).
Conclusion
These results confirms the vasodilatory effects of TA on rat mesenteric artery and the activating effects on the Kv7.4 and Kv7.3/7.5 K+ channels, which may be a mechanism to explain the vasodilatory effect and this mechanism can be used in the research of antihypertension.
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Affiliation(s)
- Yuanyuan Zhang
- Department of Pharmacology, Hebei University of Chinese Medicine, Shijiazhuang, Hebei, China
| | - Xi Chu
- Department of Pharmacy, The Fourth Hospital of Hebei Medical University, Shijiazhuang, Hebei, China
| | - Ling Liu
- Department of Pharmacy, Maternal and Child Health Hospital, Tangshan, Hebei, China
| | - Nan Zhang
- Vascular Surgery, The East Branch of Second Hospital of Hebei Medical University, Shijiazhuang, Hebei, China
| | - Hui Guo
- Department of Pharmacology, Hebei University of Chinese Medicine, Shijiazhuang, Hebei, China
| | - Fan Yang
- Department of Pharmacology, Hebei University of Chinese Medicine, Shijiazhuang, Hebei, China
| | - Zhenyi Liu
- Department of Pharmacology, Hebei University of Chinese Medicine, Shijiazhuang, Hebei, China
| | - Yongsheng Dong
- Intensive Care Unit, Air Force General Hospital, Beijing, Jiangsu, China
| | - Yifan Bao
- Key Laboratory of Drug Metabolism & Pharmacokinetics, China Pharmaceutical University, Nanjing, Jiangsu, China
| | - Xuan Zhang
- Department of Pharmacology, Hebei University of Chinese Medicine, Shijiazhuang, Hebei, China
| | - Jianping Zhang
- Department of Pharmacology, Hebei University of Chinese Medicine, Shijiazhuang, Hebei, China
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Chen X, Li W, Hiett SC, Obukhov AG. Novel Roles for Kv7 Channels in Shaping Histamine-Induced Contractions and Bradykinin-Dependent Relaxations in Pig Coronary Arteries. PLoS One 2016; 11:e0148569. [PMID: 26844882 PMCID: PMC4742238 DOI: 10.1371/journal.pone.0148569] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Accepted: 01/08/2016] [Indexed: 12/22/2022] Open
Abstract
Voltage-gated Kv7 channels are inhibited by agonists of Gq-protein-coupled receptors, such as histamine. Recent works have provided evidence that inhibition of vascular Kv7 channels may trigger vessel contractions. In this study, we investigated how Kv7 activity modulates the histamine-induced contractions in "healthy" and metabolic syndrome (MetS) pig right coronary arteries (CAs). We performed isometric tension and immunohistochemical studies with domestic, lean Ossabaw, and MetS Ossabaw pig CAs. We found that neither the Kv7.2/Kv7.4/Kv7.5 activator ML213 nor the general Kv7 inhibitor XE991 altered the tension of CA rings under preload, indicating that vascular Kv7 channels are likely inactive in the preloaded rings. Conversely, ML213 potently dilated histamine-pre-contracted CAs, suggesting that Kv7 channels are activated during histamine applications and yet partially inhibited by histamine. Immunohistochemistry analysis revealed strong Kv7.4 immunostaining in the medial and intimal layers of the CA wall, whereas Kv7.5 immunostaining intensity was strong in the intimal but weak in the medial layers. The medial Kv7 immunostaining was significantly weaker in MetS Ossabaw CAs as compared to lean Ossabaw or domestic CAs. Consistently, histamine-pre-contracted MetS Ossabaw CAs exhibited attenuated ML213-dependent dilations. In domestic pig CAs, where medial Kv7 immunostaining intensity was stronger, histamine-induced contractions spontaneously decayed to ~31% of the peak amplitude within 4 minutes. Oppositely, in Ossabaw CAs, where Kv7 immunostaining intensity was weaker, the histamine-induced contractions were more sustained. XE991 pretreatment significantly slowed the decay rate of histamine-induced contractions in domestic CAs, supporting the hypothesis that increased Kv7 activity correlates with a faster rate of histamine-induced contraction decay. Alternatively, XE991 significantly decreased the amplitude of bradykinin-dependent dilations in pre-contracted CAs. We propose that in CAs, a decreased expression or a loss of function of Kv7 channels may lead to sustained histamine-induced contractions and reduced endothelium-dependent relaxation, both risk factors for coronary spasm.
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Affiliation(s)
- Xingjuan Chen
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine - Indianapolis, Indianapolis, Indiana, 46202, United States of America
| | - Wennan Li
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine - Indianapolis, Indianapolis, Indiana, 46202, United States of America
| | - S. Christopher Hiett
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine - Indianapolis, Indianapolis, Indiana, 46202, United States of America
| | - Alexander G. Obukhov
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine - Indianapolis, Indianapolis, Indiana, 46202, United States of America
- * E-mail:
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32
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Goodwill AG, Fu L, Noblet JN, Casalini ED, Sassoon D, Berwick ZC, Kassab GS, Tune JD, Dick GM. KV7 channels contribute to paracrine, but not metabolic or ischemic, regulation of coronary vascular reactivity in swine. Am J Physiol Heart Circ Physiol 2016; 310:H693-704. [PMID: 26825518 DOI: 10.1152/ajpheart.00688.2015] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Accepted: 01/20/2016] [Indexed: 12/30/2022]
Abstract
Hydrogen peroxide (H2O2) and voltage-dependent K(+) (KV) channels play key roles in regulating coronary blood flow in response to metabolic, ischemic, and paracrine stimuli. The KV channels responsible have not been identified, but KV7 channels are possible candidates. Existing data regarding KV7 channel function in the coronary circulation (limited to ex vivo assessments) are mixed. Thus we examined the hypothesis that KV7 channels are present in cells of the coronary vascular wall and regulate vasodilation in swine. We performed a variety of molecular, biochemical, and functional (in vivo and ex vivo) studies. Coronary arteries expressed KCNQ genes (quantitative PCR) and KV7.4 protein (Western blot). Immunostaining demonstrated KV7.4 expression in conduit and resistance vessels, perhaps most prominently in the endothelial and adventitial layers. Flupirtine, a KV7 opener, relaxed coronary artery rings, and this was attenuated by linopirdine, a KV7 blocker. Endothelial denudation inhibited the flupirtine-induced and linopirdine-sensitive relaxation of coronary artery rings. Moreover, linopirdine diminished bradykinin-induced endothelial-dependent relaxation of coronary artery rings. There was no effect of intracoronary flupirtine or linopirdine on coronary blood flow at the resting heart rate in vivo. Linopirdine had no effect on coronary vasodilation in vivo elicited by ischemia, H2O2, or tachycardia. However, bradykinin increased coronary blood flow in vivo, and this was attenuated by linopirdine. These data indicate that KV7 channels are expressed in some coronary cell type(s) and influence endothelial function. Other physiological functions of coronary vascular KV7 channels remain unclear, but they do appear to contribute to endothelium-dependent responses to paracrine stimuli.
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Affiliation(s)
- Adam G Goodwill
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, Indiana; and
| | - Lijuan Fu
- California Medical Innovations Institute, San Diego, California
| | - Jillian N Noblet
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, Indiana; and
| | - Eli D Casalini
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, Indiana; and
| | - Daniel Sassoon
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, Indiana; and
| | | | | | - Johnathan D Tune
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, Indiana; and
| | - Gregory M Dick
- California Medical Innovations Institute, San Diego, California
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Currò D. The Modulation of Potassium Channels in the Smooth Muscle as a Therapeutic Strategy for Disorders of the Gastrointestinal Tract. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2016; 104:263-305. [PMID: 27038377 DOI: 10.1016/bs.apcsb.2015.12.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Alterations of smooth muscle contractility contribute to the pathophysiology of important functional gastrointestinal disorders (FGIDs) such as functional dyspepsia and irritable bowel syndrome. Consequently, drugs that decrease smooth muscle contractility are effective treatments for these diseases. Smooth muscle contraction is mainly triggered by Ca(2+) influx through voltage-dependent channels located in the plasma membrane. Thus, the modulation of the membrane potential results in the regulation of Ca(2+) influx and cytosolic levels. K(+) channels play fundamental roles in these processes. The open probability of K(+) channels increases in response to various stimuli, including membrane depolarization (voltage-gated K(+) [K(V)] channels) and the increase in cytosolic Ca(2+) levels (Ca(2+)-dependent K(+) [K(Ca)] channels). K(+) channel activation is mostly associated with outward K(+) currents that hyperpolarize the membrane and reduce cell excitability and contractility. In addition, some K(+) channels are open at the resting membrane potential values of the smooth muscle cells in some gut segments and contribute to set the resting membrane potential itself. The closure of these channels induces membrane depolarization and smooth muscle contraction. K(V)1.2, 1.5, 2.2, 4.3, 7.4 and 11.1, K(Ca)1.1 and 2.3, and inwardly rectifying type 6K(+) (K(ir)6) channels play the most important functional roles in the gastrointestinal smooth muscle. Activators of all these channels may theoretically relax the gastrointestinal smooth muscle and could therefore be promising new therapeutic options for FGID. The challenge of future drug research and development in this area will be to synthesize molecules selective for the channel assemblies expressed in the gastrointestinal smooth muscle.
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Affiliation(s)
- Diego Currò
- Institute of Pharmacology, School of Medicine, Catholic University of the Sacred Heart, Rome, Italy.
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Chen Z, Hu Y, Wang B, Cao Z, Li W, Wu Y. A single conserved basic residue in the potassium channel filter region controls KCNQ1 insensitivity toward scorpion toxins. Biochem Biophys Rep 2015; 3:62-67. [PMID: 29124168 PMCID: PMC5668678 DOI: 10.1016/j.bbrep.2015.07.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2015] [Revised: 07/05/2015] [Accepted: 07/07/2015] [Indexed: 02/06/2023] Open
Abstract
Although many studies concerning the sensitivity mechanism of scorpion toxin-potassium channel interactions have been reported, few have explored the biochemical insensitivity mechanisms of potassium channel receptors toward natural scorpion toxin peptides, such as the KCNQ1 channel. Here, by sequence alignment analyses of the human KCNQ1 channel and scorpion potassium channel MmKv2, which is completely insensitive to scorpion toxins, we proposed that the insensitivity mechanism of KCNQ1 toward natural scorpion toxins might involve two functional regions, the turret and filter regions. Based on this observation, a series of KCNQ1 mutants were constructed to study molecular mechanisms of the KCNQ1 channel insensitivity toward natural scorpion toxins. Electrophysiological studies of chimera channels showed that the channel filter region controls KCNQ1 insensitivity toward the classical scorpion toxin ChTX. Interestingly, further residue mutant experiments showed that a single basic residue in the filter region determined the insensitivity of KCNQ1 channels toward scorpion toxins. Our present work showed that amino acid residue diversification at common sites controls the sensitivity and insensitivity of potassium channels toward scorpion toxins. The unique insensitivity mechanism of KCNQ1 toward natural scorpion toxins will accelerate the rational design of potent peptide inhibitors toward this channel. Insensitivity mechanism of KCNQ1 towards scorpion toxins was still unclear. A single basic residue in the KCNQ1 filter region controls its insensitivity. Amino acid residue diversification controls KCNQ1 sensitivity and insensitivity. Our work will accelerate rational design of KCNQ1 peptide inhibitors.
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Affiliation(s)
- Zongyun Chen
- Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences, Hubei University of Medicine, Hubei, China.,State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Hubei, China
| | - Youtian Hu
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Hubei, China
| | - Bin Wang
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Hubei, China
| | - Zhijian Cao
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Hubei, China
| | - Wenxin Li
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Hubei, China
| | - Yingliang Wu
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Hubei, China
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Salomonsson M, Brasen JC, Braunstein TH, Hagelqvist P, Holstein-Rathlou NH, Sorensen CM. K(V)7.4 channels participate in the control of rodent renal vascular resting tone. Acta Physiol (Oxf) 2015; 214:402-14. [PMID: 25965962 DOI: 10.1111/apha.12525] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Revised: 01/19/2015] [Accepted: 05/06/2015] [Indexed: 01/07/2023]
Abstract
AIM We tested the hypothesis that K(V)7 channels contribute to basal renal vascular tone and that they participate in agonist-induced renal vasoconstriction or vasodilation. METHODS KV 7 channel subtypes in renal arterioles were characterized by immunofluorescence. Renal blood flow (RBF) was measured using an ultrasonic flow probe. The isometric tension of rat interlobar arteries was examined in a wire myograph. Mice afferent arteriolar diameter was assessed utilizing the perfused juxtamedullary nephron technique. RESULTS Immunofluorescence revealed that K(V)7.4 channels were expressed in rat afferent arterioles. The K(V)7 blocker XE991 dose-dependently increased the isometric tension of rat interlobar arteries and caused a small (approx. 4.5%) RBF reduction in vivo. Nifedipine abolished these effects. Likewise, XE991 reduced mouse afferent arteriolar diameter by approx. 5%. The K(V)7.2-5 stimulator flupirtine dose-dependently relaxed isolated rat interlobar arteries and increased (approx. 5%) RBF in vivo. The RBF responses to NE or Ang II administration were not affected by pre-treatment with XE991 or flupirtine. XE991 pre-treatment caused a minor augmentation of the acetylcholine-induced increase in RBF, while flupirtine pre-treatment did not affect this response. CONCLUSION It is concluded that K(V)7 channels, via nifedipine sensitive channels, have a role in the regulation of basal renal vascular tone. There is no indication that K(V)7 channels have an effect on agonist-induced renal vasoconstriction while there is a small effect on acetylcholine-induced vasodilation.
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Affiliation(s)
- M. Salomonsson
- Division of Renal and Vascular Physiology; Department of Biomedical Sciences; University of Copenhagen; Copenhagen Denmark
| | - J. C. Brasen
- Division of Renal and Vascular Physiology; Department of Biomedical Sciences; University of Copenhagen; Copenhagen Denmark
- Biomedical Engineering; Department of Electrical Engineering; Technical University of Denmark; Lyngby Denmark
| | - T. H. Braunstein
- Danish National Research Foundation Center for Cardiac Arrhythmia; University of Copenhagen; Copenhagen Denmark
| | - P. Hagelqvist
- Division of Renal and Vascular Physiology; Department of Biomedical Sciences; University of Copenhagen; Copenhagen Denmark
| | - N.-H. Holstein-Rathlou
- Division of Renal and Vascular Physiology; Department of Biomedical Sciences; University of Copenhagen; Copenhagen Denmark
- Danish National Research Foundation Center for Cardiac Arrhythmia; University of Copenhagen; Copenhagen Denmark
| | - C. M. Sorensen
- Division of Renal and Vascular Physiology; Department of Biomedical Sciences; University of Copenhagen; Copenhagen Denmark
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G-protein βγ subunits are positive regulators of Kv7.4 and native vascular Kv7 channel activity. Proc Natl Acad Sci U S A 2015; 112:6497-502. [PMID: 25941381 DOI: 10.1073/pnas.1418605112] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Kv7.4 channels are a crucial determinant of arterial diameter both at rest and in response to endogenous vasodilators. However, nothing is known about the factors that ensure effective activity of these channels. We report that G-protein βγ subunits increase the amplitude and activation rate of whole-cell voltage-dependent K(+) currents sensitive to the Kv7 blocker linopirdine in HEK cells heterologously expressing Kv7.4, and in rat renal artery myocytes. In excised patch recordings, Gβγ subunits (2-250 ng /mL) enhanced the open probability of Kv7.4 channels without changing unitary conductance. Kv7 channel activity was also augmented by stimulation of G-protein-coupled receptors. Gallein, an inhibitor of Gβγ subunits, prevented these stimulatory effects. Moreover, gallein and two other structurally different Gβγ subunit inhibitors (GRK2i and a β-subunit antibody) abolished Kv7 channel currents in the absence of either Gβγ subunit enrichment or G-protein-coupled receptor stimulation. Proximity ligation assay revealed that Kv7.4 and Gβγ subunits colocalized in HEK cells and renal artery smooth muscle cells. Gallein disrupted this colocalization, contracted whole renal arteries to a similar degree as the Kv7 inhibitor linopirdine, and impaired isoproterenol-induced relaxations. Furthermore, mSIRK, which disassociates Gβγ subunits from α subunits without stimulating nucleotide exchange, relaxed precontracted arteries in a linopirdine-sensitive manner. These results reveal that Gβγ subunits are fundamental for Kv7.4 activation and crucial for vascular Kv7 channel activity, which has major consequences for the regulation of arterial tone.
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37
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Li SS, Ran YJ, Zhang DD, Li SZ, Zhu D. MicroRNA-190 regulates hypoxic pulmonary vasoconstriction by targeting a voltage-gated K⁺ channel in arterial smooth muscle cells. J Cell Biochem 2014; 115:1196-205. [PMID: 24446351 DOI: 10.1002/jcb.24771] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Accepted: 01/16/2014] [Indexed: 01/02/2023]
Abstract
Pulmonary arterial hypertension (PAH) is associated with sustained vasoconstriction, profound structural remodeling of vasculatures and alterations in Ca(2+) homeostasis in arterial smooth muscle cells (SMCs), while the underlying mechanisms are still elusive. By regulating the expression of proteins, microRNAs (miRNAs) are known to play an important role in cell fates including differentiation, apoptosis and proliferation, and may be involved in the development of PAH. Based on our previous study, hypoxia produced a significant increase of the miR-190 level in the pulmonary artery (PA), here, we used synthetic miR-190 to mimic the increase in hypoxic conditions and showed evidence for the effects of miR-190 on pulmonary arterial vasoconstriction and Ca(2+) influx in arterial SMCs. Synthetic miR-190 remarkably enhanced the vasoconstriction responses to phenylephrine (PE) and KCl. The voltage-gated K(+) channel subfamily member, Kcnq5, mRNA was shown to be a target for miR-190. Meanwhile, miR-190 antisense oligos can partially reverse the effects of miR-190 on PASMCs and PAs. Therefore, these results suggest that miR-190 appears to be a positive regulator of Ca(2+) influx, and plays an important role in hypoxic pulmonary vascular constriction.
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Affiliation(s)
- Shan-Shan Li
- Department of Biopharmaceutical Sciences, College of Pharmacy, Harbin Medical University, China; Department of Biopharmaceutical Key Laboratory of Heilongjiang Province, 157 Baojian Road, Nangang District, Harbin, Heilongjiang, 150081, PR China
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38
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Tong WC, Tribe RM, Smith R, Taggart MJ. Computational modeling reveals key contributions of KCNQ and hERG currents to the malleability of uterine action potentials underpinning labor. PLoS One 2014; 9:e114034. [PMID: 25474527 PMCID: PMC4256391 DOI: 10.1371/journal.pone.0114034] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Accepted: 11/03/2014] [Indexed: 11/19/2022] Open
Abstract
The electrical excitability of uterine smooth muscle cells is a key determinant of the contraction of the organ during labor and is manifested by spontaneous, periodic action potentials (APs). Near the end of term, APs vary in shape and size reflecting an ability to change the frequency, duration and amplitude of uterine contractions. A recent mathematical model quantified several ionic features of the electrical excitability in uterine smooth muscle cells. It replicated many of the experimentally recorded uterine AP configurations but its limitations were evident when trying to simulate the long-duration bursting APs characteristic of labor. A computational parameter search suggested that delayed rectifying K(+) currents could be a key model component requiring improvement to produce the longer-lasting bursting APs. Of the delayed rectifying K(+) currents family it is of interest that KCNQ and hERG channels have been reported to be gestationally regulated in the uterus. These currents exhibit features similar to the broadly defined uterine IK1 of the original mathematical model. We thus formulated new quantitative descriptions for several I(KCNQ) and I(hERG). Incorporation of these currents into the uterine cell model enabled simulations of the long-lasting bursting APs. Moreover, we used this modified model to simulate the effects of different contributions of I(KCNQ) and I(hERG) on AP form. Our findings suggest that the alterations in expression of hERG and KCNQ channels can potentially provide a mechanism for fine tuning of AP forms that lends a malleability for changing between plateau-like and long-lasting bursting-type APs as uterine cells prepare for parturition.
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Affiliation(s)
- Wing-Chiu Tong
- Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Rachel M. Tribe
- Division of Women's Health, King's College London and King's Health Partners, London, United Kingdom
| | - Roger Smith
- Hunter Medical Research Institute, University of Newcastle, New Lambton, New South Wales, Australia
| | - Michael J. Taggart
- Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom
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39
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Anderson UA, Carson C, Johnston L, Joshi S, Gurney AM, McCloskey KD. Functional expression of KCNQ (Kv7) channels in guinea pig bladder smooth muscle and their contribution to spontaneous activity. Br J Pharmacol 2014; 169:1290-304. [PMID: 23586426 PMCID: PMC3746117 DOI: 10.1111/bph.12210] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Revised: 03/15/2013] [Accepted: 03/26/2013] [Indexed: 12/30/2022] Open
Abstract
Background and Purpose The aim of the study was to determine whether KCNQ channels are functionally expressed in bladder smooth muscle cells (SMC) and to investigate their physiological significance in bladder contractility. Experimental Approach KCNQ channels were examined at the genetic, protein, cellular and tissue level in guinea pig bladder smooth muscle using RT-PCR, immunofluorescence, patch-clamp electrophysiology, calcium imaging, detrusor strip myography, and a panel of KCNQ activators and inhibitors. Key Results KCNQ subtypes 1–5 are expressed in bladder detrusor smooth muscle. Detrusor strips typically displayed TTX-insensitive myogenic spontaneous contractions that were increased in amplitude by the KCNQ channel inhibitors XE991, linopirdine or chromanol 293B. Contractility was inhibited by the KCNQ channel activators flupirtine or meclofenamic acid (MFA). The frequency of Ca2+-oscillations in SMC contained within bladder tissue sheets was increased by XE991. Outward currents in dispersed bladder SMC, recorded under conditions where BK and KATP currents were minimal, were significantly reduced by XE991, linopirdine, or chromanol, and enhanced by flupirtine or MFA. XE991 depolarized the cell membrane and could evoke transient depolarizations in quiescent cells. Flupirtine (20 μM) hyperpolarized the cell membrane with a simultaneous cessation of any spontaneous electrical activity. Conclusions and Implications These novel findings reveal the role of KCNQ currents in the regulation of the resting membrane potential of detrusor SMC and their important physiological function in the control of spontaneous contractility in the guinea pig bladder.
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Affiliation(s)
- U A Anderson
- Centre for Cancer Research and Cell Biology, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, UK
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Fretwell LV, Woolard J. Cardiovascular responses to retigabine in conscious rats--under normotensive and hypertensive conditions. Br J Pharmacol 2014; 169:1279-89. [PMID: 23581476 DOI: 10.1111/bph.12203] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2012] [Revised: 03/08/2013] [Accepted: 03/22/2013] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND AND PURPOSE Retigabine is a recently approved antiepileptic agent which activates Kv7.2-7.5 potassium channels. It is emerging that these channels have an important role in vascular regulation, but the vascular effects of retigabine in the conscious state are unknown. Hence, in the present study we assessed the regional haemodynamic responses to retigabine in conscious rats. EXPERIMENTAL APPROACH Male Sprague Dawley rats were chronically instrumented with pulsed Doppler flow probes to measure regional haemodynamic responses to retigabine under control conditions and during acute hypertension induced by infusion of angiotensin II and arginine vasopressin. Further experiments were performed, using the β-adrenoceptor antagonists CGP 20712A, ICI 118551 and propranolol, to elucidate the roles of β-adrenoceptors in the responses to retigabine in vivo and in vitro. KEY RESULTS Under normotensive conditions, retigabine induced dose-dependent hypotension and hindquarters vasodilatation, with small, transient renal and mesenteric vasodilatations. In the acutely hypertensive state, the renal and mesenteric, but not hindquarters, vasodilatations were enhanced. The response of the hindquarters vascular bed to retigabine was mediated, in part, by β₂-adrenoceptors. However, in vitro experiments confirmed that retigabine did not act as a β-adrenoceptor agonist. CONCLUSIONS AND IMPLICATIONS We demonstrated that retigabine causes regionally specific vasodilatations, which are different under normotensive and hypertensive conditions, and are, in part, mediated by β₂-adrenoceptors in some vascular beds but not in others. These results broadly support previous findings and further indicate that Kv7 channels are a potential therapeutic target for the treatment of vascular diseases associated with inappropriate vasoconstriction.
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Affiliation(s)
- L V Fretwell
- Institute of Cell Signalling, Medical School, Queen's Medical Centre, University of Nottingham, Nottingham, UK
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41
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Hedegaard ER, Nielsen BD, Kun A, Hughes AD, Krøigaard C, Mogensen S, Matchkov VV, Fröbert O, Simonsen U. KV 7 channels are involved in hypoxia-induced vasodilatation of porcine coronary arteries. Br J Pharmacol 2014; 171:69-82. [PMID: 24111896 DOI: 10.1111/bph.12424] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Revised: 07/08/2013] [Accepted: 09/04/2013] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND AND PURPOSE Hypoxia causes vasodilatation of coronary arteries, but the underlying mechanisms are poorly understood. We hypothesized that hypoxia reduces intracellular Ca(2+) concentration ([Ca(2+)](i)) by opening of K channels and release of H₂S. EXPERIMENTAL APPROACH Porcine coronary arteries without endothelium were mounted for measurement of isometric tension and [Ca(2+)](i), and the expression of voltage-gated K channels K(V)7 channels (encoded by KCNQ genes) and large-conductance calcium-activated K channels (K(Ca)1.1) was examined. Voltage clamp assessed the role of K(V)7 channels in hypoxia. KEY RESULTS Gradual reduction of oxygen concentration from 95 to 1% dilated the precontracted coronary arteries and this was associated with reduced [Ca(2+)](i) in PGF(2α) (10 μM)-contracted arteries whereas no fall in [Ca(2+)](i) was observed in 30 mM K-contracted arteries. Blockers of ATP-sensitive voltage-gated potassium channels and K(Ca)1.1 inhibited hypoxia-induced dilatation in PGF2α -contracted arteries; this inhibition was more marked in the presence of the K(v)7 channel blockers, XE991 and linopirdine, while a K(V)7.1 blocker, failed to change hypoxic vasodilatation. XE991 also inhibited H₂S- and adenosine-induced vasodilatation. PCR revealed the expression of K(V)7.1, K(V)7.4, K(V)7.5 and K(Ca)1.1 channels, and K(Ca)1.1, K(V)7.4 and K(V)7.5 were also identified by immunoblotting. Voltage clamp studies showed the XE991-sensitive current was more marked in hypoxic conditions. CONCLUSION The K(V)7.4 and K(V)7.5 channels, which we identified in the coronary arteries, appear to have a major role in hypoxia-induced vasodilatation. The voltage clamp results further support the involvement of K(V)7 channels in this vasodilatation. Activation of these K(V)7 channels may be induced by H₂S and adenosine.
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Affiliation(s)
- E R Hedegaard
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, University of Aarhus, Aarhus, Denmark
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Oliveras A, Roura-Ferrer M, Solé L, de la Cruz A, Prieto A, Etxebarria A, Manils J, Morales-Cano D, Condom E, Soler C, Cogolludo A, Valenzuela C, Villarroel A, Comes N, Felipe A. Functional assembly of Kv7.1/Kv7.5 channels with emerging properties on vascular muscle physiology. Arterioscler Thromb Vasc Biol 2014; 34:1522-30. [PMID: 24855057 DOI: 10.1161/atvbaha.114.303801] [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
OBJECTIVE Voltage-dependent K(+) (Kv) channels from the Kv7 family are expressed in blood vessels and contribute to cardiovascular physiology. Although Kv7 channel blockers trigger muscle contractions, Kv7 activators act as vasorelaxants. Kv7.1 and Kv7.5 are expressed in many vessels. Kv7.1 is under intense investigation because Kv7.1 blockers fail to modulate smooth muscle reactivity. In this study, we analyzed whether Kv7.1 and Kv7.5 may form functional heterotetrameric channels increasing the channel diversity in vascular smooth muscles. APPROACH AND RESULTS Kv7.1 and Kv7.5 currents elicited in arterial myocytes, oocyte, and mammalian expression systems suggest the formation of heterotetrameric complexes. Kv7.1/Kv7.5 heteromers, exhibiting different pharmacological characteristics, participate in the arterial tone. Kv7.1/Kv7.5 associations were confirmed by coimmunoprecipitation, fluorescence resonance energy transfer, and fluorescence recovery after photobleaching experiments. Kv7.1/Kv7.5 heterotetramers were highly retained at the endoplasmic reticulum. Studies in HEK-293 cells, heart, brain, and smooth and skeletal muscles demonstrated that the predominant presence of Kv7.5 stimulates release of Kv7.1/Kv7.5 oligomers out of lipid raft microdomains. Electrophysiological studies supported that KCNE1 and KCNE3 regulatory subunits further increased the channel diversity. Finally, the analysis of rat isolated myocytes and human blood vessels demonstrated that Kv7.1 and Kv7.5 exhibited a differential expression, which may lead to channel diversity. CONCLUSIONS Kv7.1 and Kv7.5 form heterotetrameric channels increasing the diversity of structures which fine-tune blood vessel reactivity. Because the lipid raft localization of ion channels is crucial for cardiovascular physiology, Kv7.1/Kv7.5 heteromers provide efficient spatial and temporal regulation of smooth muscle function. Our results shed light on the debate about the contribution of Kv7 channels to vasoconstriction and hypertension.
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Affiliation(s)
- Anna Oliveras
- From the Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain (A.O., M.R.-F., L.S., N.C., A.F.); Unidad de Biofísica, CSIC-UPV/EHU, Universidad del País Vasco, País Vasco, Spain (M.R.-F., A.E., A.V.); Instituto de Investigaciones Biomédicas "Alberto Sols" CSIC-Universidad Autónoma de Madrid, Madrid, Spain (A.d.l.C., A.P., C.V.); Departament de Patologia i Terapèutica Experimental, Hospital Universitari de Bellvitge-Universitat de Barcelona, Barcelona, Spain (J.M., E.C., C.S.); and Departamento de Farmacología, Universidad Complutense de Madrid, Ciber Enfermedades Respiratorias (CibeRes), Madrid, Spain (A.C., D.M.-C.)
| | - Meritxell Roura-Ferrer
- From the Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain (A.O., M.R.-F., L.S., N.C., A.F.); Unidad de Biofísica, CSIC-UPV/EHU, Universidad del País Vasco, País Vasco, Spain (M.R.-F., A.E., A.V.); Instituto de Investigaciones Biomédicas "Alberto Sols" CSIC-Universidad Autónoma de Madrid, Madrid, Spain (A.d.l.C., A.P., C.V.); Departament de Patologia i Terapèutica Experimental, Hospital Universitari de Bellvitge-Universitat de Barcelona, Barcelona, Spain (J.M., E.C., C.S.); and Departamento de Farmacología, Universidad Complutense de Madrid, Ciber Enfermedades Respiratorias (CibeRes), Madrid, Spain (A.C., D.M.-C.)
| | - Laura Solé
- From the Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain (A.O., M.R.-F., L.S., N.C., A.F.); Unidad de Biofísica, CSIC-UPV/EHU, Universidad del País Vasco, País Vasco, Spain (M.R.-F., A.E., A.V.); Instituto de Investigaciones Biomédicas "Alberto Sols" CSIC-Universidad Autónoma de Madrid, Madrid, Spain (A.d.l.C., A.P., C.V.); Departament de Patologia i Terapèutica Experimental, Hospital Universitari de Bellvitge-Universitat de Barcelona, Barcelona, Spain (J.M., E.C., C.S.); and Departamento de Farmacología, Universidad Complutense de Madrid, Ciber Enfermedades Respiratorias (CibeRes), Madrid, Spain (A.C., D.M.-C.)
| | - Alicia de la Cruz
- From the Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain (A.O., M.R.-F., L.S., N.C., A.F.); Unidad de Biofísica, CSIC-UPV/EHU, Universidad del País Vasco, País Vasco, Spain (M.R.-F., A.E., A.V.); Instituto de Investigaciones Biomédicas "Alberto Sols" CSIC-Universidad Autónoma de Madrid, Madrid, Spain (A.d.l.C., A.P., C.V.); Departament de Patologia i Terapèutica Experimental, Hospital Universitari de Bellvitge-Universitat de Barcelona, Barcelona, Spain (J.M., E.C., C.S.); and Departamento de Farmacología, Universidad Complutense de Madrid, Ciber Enfermedades Respiratorias (CibeRes), Madrid, Spain (A.C., D.M.-C.)
| | - Angela Prieto
- From the Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain (A.O., M.R.-F., L.S., N.C., A.F.); Unidad de Biofísica, CSIC-UPV/EHU, Universidad del País Vasco, País Vasco, Spain (M.R.-F., A.E., A.V.); Instituto de Investigaciones Biomédicas "Alberto Sols" CSIC-Universidad Autónoma de Madrid, Madrid, Spain (A.d.l.C., A.P., C.V.); Departament de Patologia i Terapèutica Experimental, Hospital Universitari de Bellvitge-Universitat de Barcelona, Barcelona, Spain (J.M., E.C., C.S.); and Departamento de Farmacología, Universidad Complutense de Madrid, Ciber Enfermedades Respiratorias (CibeRes), Madrid, Spain (A.C., D.M.-C.)
| | - Ainhoa Etxebarria
- From the Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain (A.O., M.R.-F., L.S., N.C., A.F.); Unidad de Biofísica, CSIC-UPV/EHU, Universidad del País Vasco, País Vasco, Spain (M.R.-F., A.E., A.V.); Instituto de Investigaciones Biomédicas "Alberto Sols" CSIC-Universidad Autónoma de Madrid, Madrid, Spain (A.d.l.C., A.P., C.V.); Departament de Patologia i Terapèutica Experimental, Hospital Universitari de Bellvitge-Universitat de Barcelona, Barcelona, Spain (J.M., E.C., C.S.); and Departamento de Farmacología, Universidad Complutense de Madrid, Ciber Enfermedades Respiratorias (CibeRes), Madrid, Spain (A.C., D.M.-C.)
| | - Joan Manils
- From the Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain (A.O., M.R.-F., L.S., N.C., A.F.); Unidad de Biofísica, CSIC-UPV/EHU, Universidad del País Vasco, País Vasco, Spain (M.R.-F., A.E., A.V.); Instituto de Investigaciones Biomédicas "Alberto Sols" CSIC-Universidad Autónoma de Madrid, Madrid, Spain (A.d.l.C., A.P., C.V.); Departament de Patologia i Terapèutica Experimental, Hospital Universitari de Bellvitge-Universitat de Barcelona, Barcelona, Spain (J.M., E.C., C.S.); and Departamento de Farmacología, Universidad Complutense de Madrid, Ciber Enfermedades Respiratorias (CibeRes), Madrid, Spain (A.C., D.M.-C.)
| | - Daniel Morales-Cano
- From the Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain (A.O., M.R.-F., L.S., N.C., A.F.); Unidad de Biofísica, CSIC-UPV/EHU, Universidad del País Vasco, País Vasco, Spain (M.R.-F., A.E., A.V.); Instituto de Investigaciones Biomédicas "Alberto Sols" CSIC-Universidad Autónoma de Madrid, Madrid, Spain (A.d.l.C., A.P., C.V.); Departament de Patologia i Terapèutica Experimental, Hospital Universitari de Bellvitge-Universitat de Barcelona, Barcelona, Spain (J.M., E.C., C.S.); and Departamento de Farmacología, Universidad Complutense de Madrid, Ciber Enfermedades Respiratorias (CibeRes), Madrid, Spain (A.C., D.M.-C.)
| | - Enric Condom
- From the Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain (A.O., M.R.-F., L.S., N.C., A.F.); Unidad de Biofísica, CSIC-UPV/EHU, Universidad del País Vasco, País Vasco, Spain (M.R.-F., A.E., A.V.); Instituto de Investigaciones Biomédicas "Alberto Sols" CSIC-Universidad Autónoma de Madrid, Madrid, Spain (A.d.l.C., A.P., C.V.); Departament de Patologia i Terapèutica Experimental, Hospital Universitari de Bellvitge-Universitat de Barcelona, Barcelona, Spain (J.M., E.C., C.S.); and Departamento de Farmacología, Universidad Complutense de Madrid, Ciber Enfermedades Respiratorias (CibeRes), Madrid, Spain (A.C., D.M.-C.)
| | - Concepció Soler
- From the Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain (A.O., M.R.-F., L.S., N.C., A.F.); Unidad de Biofísica, CSIC-UPV/EHU, Universidad del País Vasco, País Vasco, Spain (M.R.-F., A.E., A.V.); Instituto de Investigaciones Biomédicas "Alberto Sols" CSIC-Universidad Autónoma de Madrid, Madrid, Spain (A.d.l.C., A.P., C.V.); Departament de Patologia i Terapèutica Experimental, Hospital Universitari de Bellvitge-Universitat de Barcelona, Barcelona, Spain (J.M., E.C., C.S.); and Departamento de Farmacología, Universidad Complutense de Madrid, Ciber Enfermedades Respiratorias (CibeRes), Madrid, Spain (A.C., D.M.-C.)
| | - Angel Cogolludo
- From the Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain (A.O., M.R.-F., L.S., N.C., A.F.); Unidad de Biofísica, CSIC-UPV/EHU, Universidad del País Vasco, País Vasco, Spain (M.R.-F., A.E., A.V.); Instituto de Investigaciones Biomédicas "Alberto Sols" CSIC-Universidad Autónoma de Madrid, Madrid, Spain (A.d.l.C., A.P., C.V.); Departament de Patologia i Terapèutica Experimental, Hospital Universitari de Bellvitge-Universitat de Barcelona, Barcelona, Spain (J.M., E.C., C.S.); and Departamento de Farmacología, Universidad Complutense de Madrid, Ciber Enfermedades Respiratorias (CibeRes), Madrid, Spain (A.C., D.M.-C.)
| | - Carmen Valenzuela
- From the Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain (A.O., M.R.-F., L.S., N.C., A.F.); Unidad de Biofísica, CSIC-UPV/EHU, Universidad del País Vasco, País Vasco, Spain (M.R.-F., A.E., A.V.); Instituto de Investigaciones Biomédicas "Alberto Sols" CSIC-Universidad Autónoma de Madrid, Madrid, Spain (A.d.l.C., A.P., C.V.); Departament de Patologia i Terapèutica Experimental, Hospital Universitari de Bellvitge-Universitat de Barcelona, Barcelona, Spain (J.M., E.C., C.S.); and Departamento de Farmacología, Universidad Complutense de Madrid, Ciber Enfermedades Respiratorias (CibeRes), Madrid, Spain (A.C., D.M.-C.)
| | - Alvaro Villarroel
- From the Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain (A.O., M.R.-F., L.S., N.C., A.F.); Unidad de Biofísica, CSIC-UPV/EHU, Universidad del País Vasco, País Vasco, Spain (M.R.-F., A.E., A.V.); Instituto de Investigaciones Biomédicas "Alberto Sols" CSIC-Universidad Autónoma de Madrid, Madrid, Spain (A.d.l.C., A.P., C.V.); Departament de Patologia i Terapèutica Experimental, Hospital Universitari de Bellvitge-Universitat de Barcelona, Barcelona, Spain (J.M., E.C., C.S.); and Departamento de Farmacología, Universidad Complutense de Madrid, Ciber Enfermedades Respiratorias (CibeRes), Madrid, Spain (A.C., D.M.-C.)
| | - Núria Comes
- From the Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain (A.O., M.R.-F., L.S., N.C., A.F.); Unidad de Biofísica, CSIC-UPV/EHU, Universidad del País Vasco, País Vasco, Spain (M.R.-F., A.E., A.V.); Instituto de Investigaciones Biomédicas "Alberto Sols" CSIC-Universidad Autónoma de Madrid, Madrid, Spain (A.d.l.C., A.P., C.V.); Departament de Patologia i Terapèutica Experimental, Hospital Universitari de Bellvitge-Universitat de Barcelona, Barcelona, Spain (J.M., E.C., C.S.); and Departamento de Farmacología, Universidad Complutense de Madrid, Ciber Enfermedades Respiratorias (CibeRes), Madrid, Spain (A.C., D.M.-C.)
| | - Antonio Felipe
- From the Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain (A.O., M.R.-F., L.S., N.C., A.F.); Unidad de Biofísica, CSIC-UPV/EHU, Universidad del País Vasco, País Vasco, Spain (M.R.-F., A.E., A.V.); Instituto de Investigaciones Biomédicas "Alberto Sols" CSIC-Universidad Autónoma de Madrid, Madrid, Spain (A.d.l.C., A.P., C.V.); Departament de Patologia i Terapèutica Experimental, Hospital Universitari de Bellvitge-Universitat de Barcelona, Barcelona, Spain (J.M., E.C., C.S.); and Departamento de Farmacología, Universidad Complutense de Madrid, Ciber Enfermedades Respiratorias (CibeRes), Madrid, Spain (A.C., D.M.-C.).
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Currò D. K+ channels as potential targets for the treatment of gastrointestinal motor disorders. Eur J Pharmacol 2014; 733:97-101. [PMID: 24726846 DOI: 10.1016/j.ejphar.2014.03.049] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Revised: 03/14/2014] [Accepted: 03/27/2014] [Indexed: 12/21/2022]
Abstract
K(+) channels play important functional roles in excitable cells, as neurons and muscle cells. The activation or inhibition of K(+) channels hyperpolarizes or depolarizes the cell membrane, respectively. These effects determine in the smooth muscle decrease or increase in Ca(2+) influx through voltage-gated Ca(2+) (CaV1.2) channels and relaxation or contraction, respectively. Recent studies highlight the importance of voltage-dependent type 7 K(+) (KV7 or KCNQ) channels in regulating muscle tone and contractility in stomach and colon. KV7 channels, that include 5 subtypes (KV7.1-7.5), are activated at relatively negative potential values, close to those of the resting membrane potential for the smooth muscle cells of some segments of the gastrointestinal tract. Thus, they contribute to set the resting membrane potential and their blockade induces increase in smooth muscle contractility in stomach and colon. In addition, KV7 channel activation produces profound relaxations of gastric and colonic smooth muscle. Therefore, KV7 channel activators could be used to relax the smooth muscle and relieve symptoms in diseases such as functional dyspepsia and irritable bowel syndrome with prevalent diarrhea. The discovery of activators selective for the channel subtypes present in the smooth muscle, mainly KV7.4 and 7.5, would allow avoiding adverse cardiac and nervous system effects. A further step forward would be characterizing putative differences among the KV7 channel subtypes expressed in the various smooth muscles and synthesizing molecules specific for the gastrointestinal smooth muscle.
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Affiliation(s)
- Diego Currò
- Institute of Pharmacology, School of Medicine, Catholic University of the Sacred Heart, L.go F. Vito 1, 00168 Rome, Italy.
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Stott JB, Jepps TA, Greenwood IA. KV7 potassium channels: a new therapeutic target in smooth muscle disorders. Drug Discov Today 2014; 19:413-24. [DOI: 10.1016/j.drudis.2013.12.003] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2013] [Revised: 10/21/2013] [Accepted: 12/04/2013] [Indexed: 12/23/2022]
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Jepps TA, Olesen SP, Greenwood IA. One man's side effect is another man's therapeutic opportunity: targeting Kv7 channels in smooth muscle disorders. Br J Pharmacol 2014; 168:19-27. [PMID: 22880633 DOI: 10.1111/j.1476-5381.2012.02133.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Retigabine is a first in class anticonvulsant that has recently undergone clinical trials to test its efficacy in epileptic patients. Retigabine's novel mechanism of action - activating Kv7 channels - suppresses neuronal activity to prevent seizure generation by hyperpolarizing the membrane potential and suppressing depolarizing surges. However, Kv7 channels are not expressed exclusively in neurones and data generated over the last decade have shown that Kv7 channels play a key role in various smooth muscle systems of the body. This review discusses the potential of targeting Kv7 channels in the smooth muscle to treat diseases such as hypertension, bladder instability, constipation and preterm labour.
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Affiliation(s)
- T A Jepps
- Division of Biomedical Sciences, St George's, University of London, Cranmer Terrace, UK
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Abstract
Ion channels play a key role in defining myometrial contractility. Modulation of ion channel populations is proposed to underpin gestational changes in uterine contractility associated with the transition from uterine quiescence to active labour. Of the myriad ion channels present in the uterus, this article will focus upon potassium channels encoded by the KCNQ genes and ether-à-go-go-related (ERG) genes. Voltage-gated potassium channels encoded by KCNQ and ERG (termed Kv7 and Kv11, respectively) are accepted as major determinants of neuronal excitability and the duration of the cardiac action potential. However, there is now growing appreciation that these ion channels have a major functional impact in vascular and non-vascular smooth muscle. Moreover, Kv7 channels may be potential therapeutic targets for the treatment of preterm labour.
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Affiliation(s)
- Iain A Greenwood
- * St George's Medical School, Division of Biomedical Sciences, London SW17 0RE, UK.
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Adduci A, Martire M, Taglialatela M, Arena V, Rizzo G, Coco C, Currò D. Expression and motor functional roles of voltage-dependent type 7 K(+) channels in the human taenia coli. Eur J Pharmacol 2013; 721:12-20. [PMID: 24120659 DOI: 10.1016/j.ejphar.2013.09.061] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Revised: 09/05/2013] [Accepted: 09/20/2013] [Indexed: 02/07/2023]
Abstract
Voltage-dependent type 7 K(+) (KV7 or KCNQ) channels modulate the excitability of neurons and muscle cells. The aims of the present study were to investigate the motor effects of KV7 channel modulators and the expression of KV7 channels in the human taenia coli. The effects of KV7 channel modulators on the muscle tone of human taenia coli strips were investigated under nonadrenergic non-nitrergic conditions by organ bath studies. Gene expression and tissue localisation of channels were studied by real-time PCR and immunohistochemistry, respectively. Under basal conditions, the KV7 channel blocker XE-991 induced concentration-dependent contractions, with mean EC50 and Emax of 18.7 μM and 30.5% respectively of the maximal bethanechol-induced contraction, respectively. The KV7 channel activators retigabine and flupirtine concentration-dependently relaxed the taenia coli, with mean EC50s of 19.2 μM and 29.9 μM, respectively. Retigabine also relaxed bethanechol-precontracted strips, with maximal relaxations of 79.2% of the bethanecol-induced precontraction. The motor effects induced by the KV7 channel modulators were not affected by tetrodotoxin or ω-conotoxin GVIA. XE-991 greatly reduced retigabine- and flupirtine-induced relaxations. Transcripts encoded by all KCNQ genes were detected in the taenia coli, with KCNQ4 showing the highest expression levels. KV7.4 channels were clearly visualised by immunohistochemistry in colonic epithelium, circular muscle layer and taenia coli. KV7 channels appear to contribute to the resting muscle tone of the human taenia coli. In addition, KV7 channel activators significantly relax the taenia coli. Thus, they could be useful therapeutic relaxant agents for colonic motor disorders.
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Affiliation(s)
- Alice Adduci
- Institute of Pharmacology, School of Medicine, Catholic University of the Sacred Heart, L.go F. Vito 1, 00168 Rome, Italy
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Afeli SAY, Malysz J, Petkov GV. Molecular expression and pharmacological evidence for a functional role of kv7 channel subtypes in Guinea pig urinary bladder smooth muscle. PLoS One 2013; 8:e75875. [PMID: 24073284 PMCID: PMC3779188 DOI: 10.1371/journal.pone.0075875] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Accepted: 08/19/2013] [Indexed: 12/30/2022] Open
Abstract
Voltage-gated Kv7 (KCNQ) channels are emerging as essential regulators of smooth muscle excitability and contractility. However, their physiological role in detrusor smooth muscle (DSM) remains to be elucidated. Here, we explored the molecular expression and function of Kv7 channel subtypes in guinea pig DSM by RT-PCR, qRT-PCR, immunohistochemistry, electrophysiology, and isometric tension recordings. In whole DSM tissue, mRNAs for all Kv7 channel subtypes were detected in a rank order: Kv7.1~Kv7.2Kv7.3~Kv7.5Kv7.4. In contrast, freshly-isolated DSM cells showed mRNA expression of: Kv7.1~Kv7.2Kv7.5Kv7.3~Kv7.4. Immunohistochemical confocal microscopy analyses of DSM, conducted by using co-labeling of Kv7 channel subtype-specific antibodies and α-smooth muscle actin, detected protein expression for all Kv7 channel subtypes, except for the Kv7.4, in DSM cells. L-364373 (R-L3), a Kv7.1 channel activator, and retigabine, a Kv7.2-7.5 channel activator, inhibited spontaneous phasic contractions and the 10-Hz electrical field stimulation (EFS)-induced contractions of DSM isolated strips. Linopiridine and XE991, two pan-Kv7 (effective at Kv7.1-Kv7.5 subtypes) channel inhibitors, had opposite effects increasing DSM spontaneous phasic and 10 Hz EFS-induced contractions. EFS-induced DSM contractions generated by a wide range of stimulation frequencies were decreased by L-364373 (10 µM) or retigabine (10 µM), and increased by XE991 (10 µM). Retigabine (10 µM) induced hyperpolarization and inhibited spontaneous action potentials in freshly-isolated DSM cells. In summary, Kv7 channel subtypes are expressed at mRNA and protein levels in guinea pig DSM cells. Their pharmacological modulation can control DSM contractility and excitability; therefore, Kv7 channel subtypes provide potential novel therapeutic targets for urinary bladder dysfunction.
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Affiliation(s)
- Serge A. Y. Afeli
- Department of Drug Discovery and Biomedical Sciences, South Carolina College of Pharmacy, University of South Carolina, Columbia, South Carolina, United States of America
| | - John Malysz
- Department of Drug Discovery and Biomedical Sciences, South Carolina College of Pharmacy, University of South Carolina, Columbia, South Carolina, United States of America
| | - Georgi V. Petkov
- Department of Drug Discovery and Biomedical Sciences, South Carolina College of Pharmacy, University of South Carolina, Columbia, South Carolina, United States of America
- * E-mail:
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White BJO, Smith PA, Dunn WR. Hydrogen sulphide-mediated vasodilatation involves the release of neurotransmitters from sensory nerves in pressurized mesenteric small arteries isolated from rats. Br J Pharmacol 2013; 168:785-93. [PMID: 22928888 DOI: 10.1111/j.1476-5381.2012.02187.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Revised: 08/15/2012] [Accepted: 08/16/2012] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND AND PURPOSE Hydrogen sulphide (H(2)S) is a gas that has recently been shown to have biological activity. In the majority of blood vessels studied so far, H(2)S has been shown to cause vasorelaxation, although contractile responses have been reported. In the present study, we have made a pharmacological assessment of the effects of H(2)S in mesenteric small arteries isolated from rats. EXPERIMENTAL APPROACH Rat mesenteric small arteries were studied using pressure myography. In pressurised arteries, responses were obtained to the H(2)S donor, sodium hydrogen sulphide (NaHS), in the absence and presence of the NOS inhibitor L-NAME, raised extracellular potassium, the K(ATP) channel inhibitor glibenclamide, the Cl- channel blockers DIDS, NPPB and A9C, the TRPV1 receptor desensitizing agent, capsaicin, the CGRP antagonist, olcegepant, the TRPV1 channel blocker capsazepine and the TRPA1 channel blocker HC-030031. KEY RESULTS NaHS produced a vasodilator response in rat mesenteric small arteries held at 90 mmHg. Responses to NaHS were not reproducible. Neither, glibenclamide nor, L-NAME inhibited responses to NaHS. DIDS abolished vasodilator responses to NaHS, but these were unaffected by the chloride channel blockers, NPPB and A9C. Responses to NaHS were attenuated after capsaicin pre-treatment, by a CGRP receptor antagonist and an inhibitor of TRPA1 channels. CONCLUSIONS AND IMPLICATIONS In small arteries isolated from the rat mesentery, NaHS caused a vasodilatation. This response was not reproducible in vitro, since it was mediated by the release of sensory neurotransmitters in a capsaicin-like action. This release was mediated by a H(2)S-induced activation of TRPA1 channels.
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Affiliation(s)
- Benjamin J O White
- Cardiovascular Research Group, School of Biomedical Sciences, University of Nottingham, Nottingham, UK
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Flupirtine, a re-discovered drug, revisited. Inflamm Res 2013; 62:251-8. [PMID: 23322112 DOI: 10.1007/s00011-013-0592-5] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Revised: 12/20/2012] [Accepted: 01/02/2013] [Indexed: 12/15/2022] Open
Abstract
Flupirtine was developed long before K(V)7 (KCNQ) channels were known. However, it was clear from the beginning that flupirtine is neither an opioid nor a nonsteroidal anti-inflammatory analgesic. Its unique muscle relaxing activity was discovered by serendipity. In the meantime, broad and intensive research has resulted in a partial clarification of its mode of action. Flupirtine is the first therapeutically used K(V)7 channel activator with additional GABA(A)ergic mechanisms and thus the first representative of a novel class of analgesics. The presently accepted main mode of its action, potassium K(V)7 (KCNQ) channel activation, opens a series of further therapeutic possibilities. One of them has now been realized: its back-up compound, the bioisostere retigabine, has been approved for the treatment of epilepsy.
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