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Zhang G, Yang H, Wang Y, Liang H, Shi J, Cui J. Redox-dependent Cd 2+ inhibition of BK-type Ca 2+-activated K + channels. Biophys J 2024:S0006-3495(24)00135-8. [PMID: 38400542 DOI: 10.1016/j.bpj.2024.02.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Revised: 01/11/2024] [Accepted: 02/20/2024] [Indexed: 02/25/2024] Open
Abstract
Large-conductance Ca2+-activated K+ channels (BK channels) are formed by Slo1 subunits as a homotetramer. Besides Ca2+, other divalent cations, such as Cd2+, also activate BK channels when applied intracellularly by shifting the conductance-voltage relation to more negative voltages. However, we found that if the inside-out patch containing BK channels was treated with solution containing reducing agents such as dithiothreitol (DTT), then subsequent Cd2+ application completely inhibited BK currents. The DTT-dependent Cd2+ inhibition could be reversed by treating the patch with solutions containing H2O2, suggesting that a redox reaction regulates the Cd2+ inhibition of BK channels. Similar DTT-dependent Cd2+ inhibition was also observed in a mutant BK channel, Core-MT, in which the cytosolic domain of the channel is deleted, and in the proton-activated Slo3 channels but not observed in the voltage-gated Shaker K+ channels. A possible mechanism for the DTT-dependent Cd2+ inhibition is that DTT treatment breaks one or more disulfide bonds between cysteine pairs in the BK channel protein and the freed thiol groups coordinate with Cd2+ to form an ion bridge that blocks the channel or locks the channel at the closed state. However, surprisingly, none of the mutations of all cysteine residues in Slo1 affect the DTT-dependent Cd2+ inhibition. These results are puzzling, with an apparent contradiction: on one hand, a redox reaction seems to regulate Cd2+ inhibition of the channel, but on the other hand, no cysteine residue in the Slo1 subunit seems to be involved in such inhibition.
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Affiliation(s)
- Guohui Zhang
- Department of Biomedical Engineering, Washington University, St. Louis, Missouri
| | - Huanghe Yang
- Department of Biomedical Engineering, Washington University, St. Louis, Missouri; Department of Biochemistry, Duke University Medical Center, Durham, North Carolina
| | - Yuyin Wang
- Department of Biomedical Engineering, Washington University, St. Louis, Missouri
| | - Hongwu Liang
- Department of Biomedical Engineering, Washington University, St. Louis, Missouri
| | - Jingyi Shi
- Department of Biomedical Engineering, Washington University, St. Louis, Missouri
| | - Jianmin Cui
- Department of Biomedical Engineering, Washington University, St. Louis, Missouri.
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2
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Sanders KM, Drumm BT, Cobine CA, Baker SA. Ca 2+ dynamics in interstitial cells: foundational mechanisms for the motor patterns in the gastrointestinal tract. Physiol Rev 2024; 104:329-398. [PMID: 37561138 DOI: 10.1152/physrev.00036.2022] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 06/29/2023] [Accepted: 08/06/2023] [Indexed: 08/11/2023] Open
Abstract
The gastrointestinal (GI) tract displays multiple motor patterns that move nutrients and wastes through the body. Smooth muscle cells (SMCs) provide the forces necessary for GI motility, but interstitial cells, electrically coupled to SMCs, tune SMC excitability, transduce inputs from enteric motor neurons, and generate pacemaker activity that underlies major motor patterns, such as peristalsis and segmentation. The interstitial cells regulating SMCs are interstitial cells of Cajal (ICC) and PDGF receptor (PDGFR)α+ cells. Together these cells form the SIP syncytium. ICC and PDGFRα+ cells express signature Ca2+-dependent conductances: ICC express Ca2+-activated Cl- channels, encoded by Ano1, that generate inward current, and PDGFRα+ cells express Ca2+-activated K+ channels, encoded by Kcnn3, that generate outward current. The open probabilities of interstitial cell conductances are controlled by Ca2+ release from the endoplasmic reticulum. The resulting Ca2+ transients occur spontaneously in a stochastic manner. Ca2+ transients in ICC induce spontaneous transient inward currents and spontaneous transient depolarizations (STDs). Neurotransmission increases or decreases Ca2+ transients, and the resulting depolarizing or hyperpolarizing responses conduct to other cells in the SIP syncytium. In pacemaker ICC, STDs activate voltage-dependent Ca2+ influx, which initiates a cluster of Ca2+ transients and sustains activation of ANO1 channels and depolarization during slow waves. Regulation of GI motility has traditionally been described as neurogenic and myogenic. Recent advances in understanding Ca2+ handling mechanisms in interstitial cells and how these mechanisms influence motor patterns of the GI tract suggest that the term "myogenic" should be replaced by the term "SIPgenic," as this review discusses.
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Affiliation(s)
- Kenton M Sanders
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada-Reno, Reno, Nevada, United States
| | - Bernard T Drumm
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
| | - Caroline A Cobine
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
| | - Salah A Baker
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada-Reno, Reno, Nevada, United States
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3
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Nordquist EB, Jia Z, Chen J. Inner pore hydration free energy controls the activation of big potassium channels. Biophys J 2023; 122:1158-1167. [PMID: 36774534 PMCID: PMC10111268 DOI: 10.1016/j.bpj.2023.02.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2022] [Revised: 01/24/2023] [Accepted: 02/07/2023] [Indexed: 02/12/2023] Open
Abstract
Hydrophobic gating is an emerging mechanism in regulation of protein ion channels where the pore remains physically open but becomes dewetted to block ion permeation. Atomistic molecular dynamics simulations have played a crucial role in understanding hydrophobic gating by providing the molecular details to complement mutagenesis and structural studies. However, existing studies rely on direct simulations and do not quantitatively describe how the sequence and structural changes may control the delicate liquid-vapor equilibrium of confined water in the pore of the channel protein. To address this limitation, we explore two enhanced sampling methods, namely metadynamics and umbrella sampling, to derive free-energy profiles of pore hydration in both the closed and open states of big potassium (BK) channels, which are important in cardiovascular and neural systems. It was found that metadynamics required substantially longer sampling times and struggled to generate stably converged free-energy profiles due to the slow dynamics of cooperative pore water diffusion even in the barrierless limit. Using umbrella sampling, well-converged free-energy profiles can be readily generated for the wild-type BK channels as well as three mutants with pore-lining mutations experimentally known to dramatically perturb the channel gating voltage. The results show that the free energy of pore hydration faithfully reports the gating voltage of the channel, providing further support for hydrophobic gating in BK channels. Free-energy analysis of pore hydration should provide a powerful approach for quantitative studies of how protein sequence, structure, solution conditions, and/or drug binding may modulate hydrophobic gating in ion channels.
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Affiliation(s)
- Erik B Nordquist
- Department of Chemistry, University of Massachusetts Amherst, Amherst, Massachusetts
| | - Zhiguang Jia
- Department of Chemistry, University of Massachusetts Amherst, Amherst, Massachusetts
| | - Jianhan Chen
- Department of Chemistry, University of Massachusetts Amherst, Amherst, Massachusetts.
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4
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Dixon RE, Trimmer JS. Endoplasmic Reticulum-Plasma Membrane Junctions as Sites of Depolarization-Induced Ca 2+ Signaling in Excitable Cells. Annu Rev Physiol 2023; 85:217-243. [PMID: 36202100 PMCID: PMC9918718 DOI: 10.1146/annurev-physiol-032122-104610] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Membrane contact sites between endoplasmic reticulum (ER) and plasma membrane (PM), or ER-PM junctions, are found in all eukaryotic cells. In excitable cells they play unique roles in organizing diverse forms of Ca2+ signaling as triggered by membrane depolarization. ER-PM junctions underlie crucial physiological processes such as excitation-contraction coupling, smooth muscle contraction and relaxation, and various forms of activity-dependent signaling and plasticity in neurons. In many cases the structure and molecular composition of ER-PM junctions in excitable cells comprise important regulatory feedback loops linking depolarization-induced Ca2+ signaling at these sites to the regulation of membrane potential. Here, we describe recent findings on physiological roles and molecular composition of native ER-PM junctions in excitable cells. We focus on recent studies that provide new insights into canonical forms of depolarization-induced Ca2+ signaling occurring at junctional triads and dyads of striated muscle, as well as the diversity of ER-PM junctions in these cells and in smooth muscle and neurons.
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Affiliation(s)
- Rose E Dixon
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, California, USA;
| | - James S Trimmer
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, California, USA;
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5
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Zhang G, Xu X, Jia Z, Geng Y, Liang H, Shi J, Marras M, Abella C, Magleby KL, Silva JR, Chen J, Zou X, Cui J. An allosteric modulator activates BK channels by perturbing coupling between Ca 2+ binding and pore opening. Nat Commun 2022; 13:6784. [PMID: 36351900 PMCID: PMC9646747 DOI: 10.1038/s41467-022-34359-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Accepted: 10/21/2022] [Indexed: 11/10/2022] Open
Abstract
BK type Ca2+-activated K+ channels activate in response to both voltage and Ca2+. The membrane-spanning voltage sensor domain (VSD) activation and Ca2+ binding to the cytosolic tail domain (CTD) open the pore across the membrane, but the mechanisms that couple VSD activation and Ca2+ binding to pore opening are not clear. Here we show that a compound, BC5, identified from in silico screening, interacts with the CTD-VSD interface and specifically modulates the Ca2+ dependent activation mechanism. BC5 activates the channel in the absence of Ca2+ binding but Ca2+ binding inhibits BC5 effects. Thus, BC5 perturbs a pathway that couples Ca2+ binding to pore opening to allosterically affect both, which is further supported by atomistic simulations and mutagenesis. The results suggest that the CTD-VSD interaction makes a major contribution to the mechanism of Ca2+ dependent activation and is an important site for allosteric agonists to modulate BK channel activation.
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Affiliation(s)
- Guohui Zhang
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, Cardiac Bioelectricity and Arrhythmia Center, Washington University, St. Louis, MO, USA
| | - Xianjin Xu
- Dalton Cardiovascular Research Center, University of Missouri - Columbia, Columbia, MO, USA.,Department of Physics and Astronomy, University of Missouri - Columbia, Columbia, MO, USA.,Department of Biochemistry, University of Missouri - Columbia, Columbia, MO, USA.,Institute for Data Science and Informatics, University of Missouri - Columbia, Columbia, MO, USA
| | - Zhiguang Jia
- Department of Chemistry, University of Massachusetts, Amherst, MA, USA.,Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, MA, USA
| | - Yanyan Geng
- Department of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Hongwu Liang
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, Cardiac Bioelectricity and Arrhythmia Center, Washington University, St. Louis, MO, USA
| | - Jingyi Shi
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, Cardiac Bioelectricity and Arrhythmia Center, Washington University, St. Louis, MO, USA
| | - Martina Marras
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, Cardiac Bioelectricity and Arrhythmia Center, Washington University, St. Louis, MO, USA
| | - Carlota Abella
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, Cardiac Bioelectricity and Arrhythmia Center, Washington University, St. Louis, MO, USA
| | - Karl L Magleby
- Department of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Jonathan R Silva
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, Cardiac Bioelectricity and Arrhythmia Center, Washington University, St. Louis, MO, USA.
| | - Jianhan Chen
- Department of Chemistry, University of Massachusetts, Amherst, MA, USA. .,Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, MA, USA.
| | - Xiaoqin Zou
- Dalton Cardiovascular Research Center, University of Missouri - Columbia, Columbia, MO, USA. .,Department of Physics and Astronomy, University of Missouri - Columbia, Columbia, MO, USA. .,Department of Biochemistry, University of Missouri - Columbia, Columbia, MO, USA. .,Institute for Data Science and Informatics, University of Missouri - Columbia, Columbia, MO, USA.
| | - Jianmin Cui
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, Cardiac Bioelectricity and Arrhythmia Center, Washington University, St. Louis, MO, USA.
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6
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Daghbouche-Rubio N, López-López JR, Pérez-García MT, Cidad P. Vascular smooth muscle ion channels in essential hypertension. Front Physiol 2022; 13:1016175. [PMID: 36213221 PMCID: PMC9540222 DOI: 10.3389/fphys.2022.1016175] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Accepted: 08/31/2022] [Indexed: 11/13/2022] Open
Abstract
Hypertension is a highly prevalent chronic disease and the major risk factor for cardiovascular diseases, the leading cause of death worldwide. Hypertension is characterized by an increased vascular tone determined by the contractile state of vascular smooth muscle cells that depends on intracellular calcium levels. The interplay of ion channels determine VSMCs membrane potential and thus intracellular calcium that controls the degree of contraction, vascular tone and blood pressure. Changes in ion channels expression and function have been linked to hypertension, but the mechanisms and molecular entities involved are not completely clear. Furthermore, the literature shows discrepancies regarding the contribution of different ion channels to hypertension probably due to differences both in the vascular preparation and in the model of hypertension employed. Animal models are essential to study this multifactorial disease but it is also critical to know their characteristics to interpret properly the results obtained. In this review we summarize previous studies, using the hypertensive mouse (BPH) and its normotensive control (BPN), focused on the identified changes in the expression and function of different families of ion channels. We will focus on L-type voltage-dependent Ca2+ channels (Cav1.2), canonical transient receptor potential channels and four different classes of K+ channels: voltage-activated (Kv), large conductance Ca2+-activated (BK), inward rectifiers (Kir) and ATP-sensitive (KATP) K+ channels. We will describe the role of these channels in hypertension and we will discuss the importance of integrating individual changes in a global context to understand the complex interplay of ion channels in hypertension.
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7
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King DR, Sedovy MW, Eaton X, Dunaway LS, Good ME, Isakson BE, Johnstone SR. Cell-To-Cell Communication in the Resistance Vasculature. Compr Physiol 2022; 12:3833-3867. [PMID: 35959755 DOI: 10.1002/cphy.c210040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The arterial vasculature can be divided into large conduit arteries, intermediate contractile arteries, resistance arteries, arterioles, and capillaries. Resistance arteries and arterioles primarily function to control systemic blood pressure. The resistance arteries are composed of a layer of endothelial cells oriented parallel to the direction of blood flow, which are separated by a matrix layer termed the internal elastic lamina from several layers of smooth muscle cells oriented perpendicular to the direction of blood flow. Cells within the vessel walls communicate in a homocellular and heterocellular fashion to govern luminal diameter, arterial resistance, and blood pressure. At rest, potassium currents govern the basal state of endothelial and smooth muscle cells. Multiple stimuli can elicit rises in intracellular calcium levels in either endothelial cells or smooth muscle cells, sourced from intracellular stores such as the endoplasmic reticulum or the extracellular space. In general, activation of endothelial cells results in the production of a vasodilatory signal, usually in the form of nitric oxide or endothelial-derived hyperpolarization. Conversely, activation of smooth muscle cells results in a vasoconstriction response through smooth muscle cell contraction. © 2022 American Physiological Society. Compr Physiol 12: 1-35, 2022.
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Affiliation(s)
- D Ryan King
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Center for Vascular and Heart Research, Virginia Tech, Roanoke, Virginia, USA
| | - Meghan W Sedovy
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Center for Vascular and Heart Research, Virginia Tech, Roanoke, Virginia, USA.,Translational Biology, Medicine, and Health Graduate Program, Virginia Tech, Blacksburg, Virginia, USA
| | - Xinyan Eaton
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Center for Vascular and Heart Research, Virginia Tech, Roanoke, Virginia, USA
| | - Luke S Dunaway
- Robert M. Berne Cardiovascular Research Centre, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Miranda E Good
- Molecular Cardiology Research Institute, Tufts Medical Center, Boston, Massachusetts, USA
| | - Brant E Isakson
- Robert M. Berne Cardiovascular Research Centre, University of Virginia School of Medicine, Charlottesville, Virginia, USA.,Department of Molecular Physiology and Biophysics, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Scott R Johnstone
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Center for Vascular and Heart Research, Virginia Tech, Roanoke, Virginia, USA.,Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, USA
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8
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Sancho M, Kyle BD. The Large-Conductance, Calcium-Activated Potassium Channel: A Big Key Regulator of Cell Physiology. Front Physiol 2021; 12:750615. [PMID: 34744788 PMCID: PMC8567177 DOI: 10.3389/fphys.2021.750615] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 09/29/2021] [Indexed: 12/01/2022] Open
Abstract
Large-conductance Ca2+-activated K+ channels facilitate the efflux of K+ ions from a variety of cells and tissues following channel activation. It is now recognized that BK channels undergo a wide range of pre- and post-translational modifications that can dramatically alter their properties and function. This has downstream consequences in affecting cell and tissue excitability, and therefore, function. While finding the “silver bullet” in terms of clinical therapy has remained elusive, ongoing research is providing an impressive range of viable candidate proteins and mechanisms that associate with and modulate BK channel activity, respectively. Here, we provide the hallmarks of BK channel structure and function generally, and discuss important milestones in the efforts to further elucidate the diverse properties of BK channels in its many forms.
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Affiliation(s)
- Maria Sancho
- Department of Pharmacology, University of Vermont, Burlington, VT, United States
| | - Barry D Kyle
- Department of Pathology and Laboratory Medicine, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada
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9
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Petkov VH, Ardasheva RG, Prissadova NA, Kristev AD, Stoyanov PS, Argirova MD. Receptor-mediated biological effects of extracts obtained from three Asplenium species. Z NATURFORSCH C 2021; 76:367-373. [PMID: 33823097 DOI: 10.1515/znc-2020-0223] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 03/13/2021] [Indexed: 11/15/2022]
Abstract
This study reports the effects of aqueous extracts obtained from three fern species of Bulgarian origin: Asplenium ceterach L., Asplenium scolopendrium L., and Asplenium trichomanes L. on the contractility and bioelectrogenesis of rat gastric smooth muscle tissues. In the concentration range 0.015-0.150 mg/mL the three extracts contracted smooth muscle tissues in a concentration-dependent manner. The contractions caused by A. ceterach L. and A. scolopendrium L. extracts (0.150 mg/mL) were reduced by ketanserin (5 × 10-7 and 5 × 10-6 mol/L), an antagonist of serotonin 5-HT2 receptor. The contraction evoked by A. trichomanes L. (0.150 mg/mL) was significantly reduced by 1 × 10-6 mol/L atropine, an antagonist of muscarinic receptors, and turned into relaxation against the background of 3 × 10-7 mol/L galantamine. After combined pretreatment with galantamine and l-arginine (5 × 10-4 mol/L), this relaxation become more pronounced. The study demonstrates that constituents of A. ceterach L. and A. scolopendrium L. extracts act as agonists of 5-HT2 receptors and cause contraction by activating serotonergic signaling system. A. trichomanes L.-induced reaction is an additive result of two opposite-in-character effects. The dominant contraction is initiated by inhibition of acetylcholinesterase activity. The relaxation develops with pre-inhibited acetylcholinesterase, it is significantly potentiated by l-arginine, and therefore associated with nitrergic signaling pathway.
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Affiliation(s)
- Venelin H Petkov
- Department of Botany and Methods of Biology Teaching, Faculty of Biology, University of Plovdiv "Paisii Hilendarski", 24 Tzar Assen Str., 4000 Plovdiv, Bulgaria
| | - Raina G Ardasheva
- Department of Medical Physics and Biophysics, Faculty of Pharmacy, Medical University of Plovdiv, 15A Vassil Aprilov Str., 4002 Plovdiv, Bulgaria
| | - Natalia A Prissadova
- Department of Medical Physics and Biophysics, Faculty of Pharmacy, Medical University of Plovdiv, 15A Vassil Aprilov Str., 4002 Plovdiv, Bulgaria
| | - Athanas D Kristev
- Department of Medical Physics and Biophysics, Faculty of Pharmacy, Medical University of Plovdiv, 15A Vassil Aprilov Str., 4002 Plovdiv, Bulgaria
| | - Plamen S Stoyanov
- Department of Botany and Methods of Biology Teaching, Faculty of Biology, University of Plovdiv "Paisii Hilendarski", 24 Tzar Assen Str., 4000 Plovdiv, Bulgaria.,Department of Bioorganic Chemistry, Faculty of Pharmacy, Medical University of Plovdiv, 15A Vassil Aprilov Str., 4002 Plovdiv, Bulgaria
| | - Mariana D Argirova
- Department of Chemical Sciences, Faculty of Pharmacy, Medical University of Plovdiv, 15A Vassil Aprilov Str., 4002 Plovdiv, Bulgaria
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10
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Sanders KM, Mutafova-Yambolieva VN. Neurotransmitters responsible for purinergic motor neurotransmission and regulation of GI motility. Auton Neurosci 2021; 234:102829. [PMID: 34146957 DOI: 10.1016/j.autneu.2021.102829] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 05/25/2021] [Accepted: 05/28/2021] [Indexed: 12/17/2022]
Abstract
Classical concepts of peripheral neurotransmission were insufficient to explain enteric inhibitory neurotransmission. Geoffrey Burnstock and colleagues developed the idea that ATP or a related purine satisfies the criteria for a neurotransmitter and serves as an enteric inhibitory neurotransmitter in GI muscles. Cloning of purinergic receptors and development of specific drugs and transgenic mice have shown that enteric inhibitory responses depend upon P2Y1 receptors in post-junctional cells. The post-junctional cells that transduce purinergic neurotransmitters in the GI tract are PDGFRα+ cells and not smooth muscle cells (SMCs). PDGFRα+ cells express P2Y1 receptors, are activated by enteric inhibitory nerve stimulation and generate Ca2+ oscillations, express small-conductance Ca2+-activated K+ channels (SK3), and generate outward currents when exposed to P2Y1 agonists. These properties are consistent with post-junctional purinergic responses, and similar responses and effectors are not functional in SMCs. Refinements in methodologies to measure purines in tissue superfusates, such as high-performance liquid chromatography (HPLC) coupled with etheno-derivatization of purines and fluorescence detection, revealed that multiple purines are released during stimulation of intrinsic nerves. β-NAD+ and other purines, better satisfy criteria for the purinergic neurotransmitter than ATP. HPLC has also allowed better detection of purine metabolites, and coupled with isolation of specific types of post-junctional cells, has provided new concepts about deactivation of purine neurotransmitters. In spite of steady progress, many unknowns about purinergic neurotransmission remain and require additional investigation to understand this important regulatory mechanism in GI motility.
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Affiliation(s)
- Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada, School of Medicine, 1664 North Virginia Street, Reno, NV 89557, USA.
| | - Violeta N Mutafova-Yambolieva
- Department of Physiology and Cell Biology, University of Nevada, School of Medicine, 1664 North Virginia Street, Reno, NV 89557, USA
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11
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Abstract
Ca2+- and voltage-gated K+ channels of large conductance (BK channels) are expressed in a diverse variety of both excitable and inexcitable cells, with functional properties presumably uniquely calibrated for the cells in which they are found. Although some diversity in BK channel function, localization, and regulation apparently arises from cell-specific alternative splice variants of the single pore-forming α subunit ( KCa1.1, Kcnma1, Slo1) gene, two families of regulatory subunits, β and γ, define BK channels that span a diverse range of functional properties. We are just beginning to unravel the cell-specific, physiological roles served by BK channels of different subunit composition.
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Affiliation(s)
- Vivian Gonzalez-Perez
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA;
| | - Christopher J Lingle
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA;
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12
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Drumm BT, Rembetski BE, Messersmith K, Manierka MS, Baker SA, Sanders KM. Pacemaker function and neural responsiveness of subserosal interstitial cells of Cajal in the mouse colon. J Physiol 2020; 598:651-681. [PMID: 31811726 DOI: 10.1113/jp279102] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 11/22/2019] [Indexed: 12/22/2022] Open
Abstract
KEY POINTS Rhythmic action potentials and intercellular Ca2+ waves are generated in smooth muscle cells of colonic longitudinal muscles (LSMC). Longitudinal muscle excitability is tuned by input from subserosal ICC (ICC-SS), a population of ICC with previously unknown function. ICC-SS express Ano1 channels and generate spontaneous Ca2+ transients in a stochastic manner. Release of Ca2+ and activation of Ano1 channels causes depolarization of ICC-SS and LSMC, leading to activation of L-type Ca2+ channels, action potentials, intercellular Ca2+ waves and contractions in LSMC. Nitrergic neural inputs regulate the Ca2+ events in ICC-SS. Pacemaker activity in longitudinal muscle is an emergent property as a result of integrated processes in ICC-SS and LSMC. ABSTRACT Much is known about myogenic mechanisms in circular muscle (CM) in the gastrointestinal tract, although less is known about longitudinal muscle (LM). Two Ca2+ signalling behaviours occur in LM: localized intracellular waves not causing contractions and intercellular waves leading to excitation-contraction coupling. An Ano1 channel antagonist inhibited intercellular Ca2+ waves and LM contractions. Ano1 channels are expressed by interstitial cells of Cajal (ICC) but not by smooth muscle cells (SMCs). We investigated Ca2+ signalling in a novel population of ICC that lies along the subserosal surface of LM (ICC-SS) in mice expressing GCaMP6f in ICC. ICC-SS fired stochastic localized Ca2+ transients. Such events have been linked to activation of Ano1 channels in ICC. Ca2+ transients in ICC-SS occurred by release from stores most probably via inositol trisphosphate receptors. This activity relied on influx via store-operated Ca2+ entry and Orai channels. No voltage-dependent mechanism that synchronized Ca2+ transients in a single cell or between cells was found. Nitrergic agonists inhibited Ca2+ transients in ICC-SS, and stimulation of intrinsic nerves activated nitrergic responses in ICC-SS. Cessation of stimulation resulted in significant enhancement of Ca2+ transients compared to the pre-stimulus activity. No evidence of innervation by excitatory, cholinergic motor neurons was found. Our data suggest that ICC-SS contribute to regulation of LM motor activity. Spontaneous Ca2+ transients activate Ano1 channels in ICC-SS. Resulting depolarization conducts to SMCs, depolarizing membrane potential, activating L-type Ca2+ channels and initiating contraction. Rhythmic electrical and mechanical behaviours of LM are an emergent property of SMCs and ICC-SS.
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Affiliation(s)
- Bernard T Drumm
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - Benjamin E Rembetski
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - Katelyn Messersmith
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - Marena S Manierka
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - Salah A Baker
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
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13
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Greenstein AS, Kadir SZAS, Csato V, Sugden SA, Baylie RA, Eisner DA, Nelson MT. Disruption of Pressure-Induced Ca 2+ Spark Vasoregulation of Resistance Arteries, Rather Than Endothelial Dysfunction, Underlies Obesity-Related Hypertension. Hypertension 2019; 75:539-548. [PMID: 31865779 PMCID: PMC7055934 DOI: 10.1161/hypertensionaha.119.13540] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Supplemental Digital Content is available in the text. Obesity-related hypertension is one of the world’s leading causes of death and yet little is understood as to how it develops. As a result, effective targeted therapies are lacking and pharmacological treatment is unfocused. To investigate underlying microvascular mechanisms, we studied small artery dysfunction in a high fat–fed mouse model of obesity. Pressure-induced constriction and responses to endothelial and vascular smooth muscle agonists were studied using myography; the corresponding intracellular Ca2+ signaling pathways were examined using confocal microscopy. Principally, we observed that the enhanced basal tone of mesenteric resistance arteries was due to failure of intraluminal pressure-induced Ca2+ spark activation of the large conductance Ca2+ activated K+ potassium channel (BK) within vascular smooth muscle cells. Specifically, the uncoupling site of this mechanotransduction pathway was at the sarcoplasmic reticulum, distal to intraluminal pressure-induced oxidation of Protein Kinase G. In contrast, the vasodilatory function of the endothelium and the underlying endothelial IP-3 and TRPV4 (vanilloid 4 transient receptor potential ion channel) Ca2+ signaling pathways were not affected by the high-fat diet or the elevated blood pressure. There were no structural alterations of the arterial wall. Our work emphasizes the importance of the intricate cellular pathway by which intraluminal pressure maintains Ca2+ spark vasoregulation in the origin of obesity-related hypertension and suggests previously unsuspected avenues for pharmacological intervention.
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Affiliation(s)
- Adam S Greenstein
- From the Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
| | | | - Viktoria Csato
- From the Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
| | - Sarah A Sugden
- From the Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
| | - Rachael A Baylie
- From the Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
| | - David A Eisner
- From the Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
| | - Mark T Nelson
- From the Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
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14
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Csato V, Kadir SZSA, Khavandi K, Bennett H, Sugden S, Gurney AM, Pritchard HT, Hill‐Eubanks D, Eaton P, Nelson MT, Greenstein AS. "A Step and a Ceiling": mechanical properties of Ca 2+ spark vasoregulation in resistance arteries by pressure-induced oxidative activation of PKG. Physiol Rep 2019; 7:e14260. [PMID: 31782255 PMCID: PMC6883097 DOI: 10.14814/phy2.14260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 07/26/2019] [Accepted: 07/27/2019] [Indexed: 11/24/2022] Open
Abstract
We investigated the biomechanical relationship between intraluminal pressure within small mesenteric resistance arteries, oxidant activation of PKG, Ca2+ sparks, and BK channel vasoregulation. Mesenteric resistance arteries from wild type (WT) and genetically modified mice with PKG resistance to oxidative activation were studied using wire and pressure myography. Ca2+ sparks and Ca2+ transients within vascular smooth muscle cells of intact arteries were characterized using high-speed confocal microscopy of intact arteries. Arteries were studied under conditions of varying intraluminal pressure and oxidation. Intraluminal pressure specifically, rather than the generic stretch of the artery, was necessary to activate the oxidative pathway. We demonstrated a graded step activation profile for the generation of Ca2+ sparks and also a functional "ceiling" for this pressure --sensitive oxidative pathway. During steady state pressure - induced constriction, any additional Ca2+ sensitive-K+ channel functional availability was independent of oxidant activated PKG. There was an increase in the amplitude, but not the Area under the Curve (AUC) of the caffeine-induced Ca2+ transient in pressurized arteries from mice with oxidant-resistant PKG compared with wild type. Overall, we surmise that intraluminal pressure within resistance arteries controls Ca2+ spark vasoregulation through a tightly controlled pathway with a graded onset switch. The pathway, underpinned by oxidant activation of PKG, cannot be further boosted by additional pressure or oxidation once active. We propose that these restrictive characteristics of pressure-induced Ca2+ spark vasoregulation confer stability for the artery in order to provide a constant flow independent of additional pressure fluctuations or exogenous oxidants.
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Affiliation(s)
- Viktoria Csato
- Division of Cardiovascular SciencesFaculty of Biology, Medicine and HealthUniversity of ManchesterHealth Innovation Manchester NetworkManchesterUnited Kingdom
- Division of Clinical PhysiologyInstitute of CardiologyResearch Centre for Molecular MedicineFaculty of MedicineUniversity of DebrecenDebrecenHungary
| | - Sharifah Z. S. A. Kadir
- Division of Cardiovascular SciencesFaculty of Biology, Medicine and HealthUniversity of ManchesterHealth Innovation Manchester NetworkManchesterUnited Kingdom
- Department of PharmacologyFaculty of MedicineUniversity of MalayaKuala LumpurMalaysia
| | - Kaivan Khavandi
- Division of Cardiovascular SciencesFaculty of Biology, Medicine and HealthUniversity of ManchesterHealth Innovation Manchester NetworkManchesterUnited Kingdom
| | - Hayley Bennett
- Division of Cardiovascular SciencesFaculty of Biology, Medicine and HealthUniversity of ManchesterHealth Innovation Manchester NetworkManchesterUnited Kingdom
| | - Sarah Sugden
- Division of Cardiovascular SciencesFaculty of Biology, Medicine and HealthUniversity of ManchesterHealth Innovation Manchester NetworkManchesterUnited Kingdom
| | - Alison M. Gurney
- Division of Cardiovascular SciencesFaculty of Biology, Medicine and HealthUniversity of ManchesterHealth Innovation Manchester NetworkManchesterUnited Kingdom
| | - Harry T. Pritchard
- Division of Cardiovascular SciencesFaculty of Biology, Medicine and HealthUniversity of ManchesterHealth Innovation Manchester NetworkManchesterUnited Kingdom
| | | | - Philip Eaton
- Centre for Clinical PharmacologyWilliam Harvey Research InstituteQueen Mary University of LondonLondonUnited Kingdom
- Present address:
Centre for Clinical PharmacologyWilliam Harvey Research InstituteQueen Mary University of LondonLondonUnited Kingdom
| | - Mark T. Nelson
- Division of Cardiovascular SciencesFaculty of Biology, Medicine and HealthUniversity of ManchesterHealth Innovation Manchester NetworkManchesterUnited Kingdom
- Department of PharmacologyUniversity of VermontBurlingtonVermont
| | - Adam S. Greenstein
- Division of Cardiovascular SciencesFaculty of Biology, Medicine and HealthUniversity of ManchesterHealth Innovation Manchester NetworkManchesterUnited Kingdom
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15
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Ottolini M, Hong K, Sonkusare SK. Calcium signals that determine vascular resistance. WILEY INTERDISCIPLINARY REVIEWS. SYSTEMS BIOLOGY AND MEDICINE 2019; 11:e1448. [PMID: 30884210 PMCID: PMC6688910 DOI: 10.1002/wsbm.1448] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2018] [Revised: 02/07/2019] [Accepted: 02/14/2019] [Indexed: 12/19/2022]
Abstract
Small arteries in the body control vascular resistance, and therefore, blood pressure and blood flow. Endothelial and smooth muscle cells in the arterial walls respond to various stimuli by altering the vascular resistance on a moment to moment basis. Smooth muscle cells can directly influence arterial diameter by contracting or relaxing, whereas endothelial cells that line the inner walls of the arteries modulate the contractile state of surrounding smooth muscle cells. Cytosolic calcium is a key driver of endothelial and smooth muscle cell functions. Cytosolic calcium can be increased either by calcium release from intracellular stores through IP3 or ryanodine receptors, or the influx of extracellular calcium through ion channels at the cell membrane. Depending on the cell type, spatial localization, source of a calcium signal, and the calcium-sensitive target activated, a particular calcium signal can dilate or constrict the arteries. Calcium signals in the vasculature can be classified into several types based on their source, kinetics, and spatial and temporal properties. The calcium signaling mechanisms in smooth muscle and endothelial cells have been extensively studied in the native or freshly isolated cells, therefore, this review is limited to the discussions of studies in native or freshly isolated cells. This article is categorized under: Biological Mechanisms > Cell Signaling Laboratory Methods and Technologies > Imaging Models of Systems Properties and Processes > Mechanistic Models.
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Affiliation(s)
- Matteo Ottolini
- Robert M. Berne Cardiovascular Research Center, University of Virginia-School of Medicine, Charlottesville, VA, 22908, USA
- Department of Pharmacology, University of Virginia-School of Medicine, Charlottesville, VA, 22908, USA
| | - Kwangseok Hong
- Robert M. Berne Cardiovascular Research Center, University of Virginia-School of Medicine, Charlottesville, VA, 22908, USA
- Department of Physical Education, Chung-Ang University, Seoul, 06974, South Korea
| | - Swapnil K. Sonkusare
- Robert M. Berne Cardiovascular Research Center, University of Virginia-School of Medicine, Charlottesville, VA, 22908, USA
- Department of Pharmacology, University of Virginia-School of Medicine, Charlottesville, VA, 22908, USA
- Department of Molecular Physiology and Biological Physics, University of Virginia-School of Medicine, Charlottesville, VA, 22908, USA
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16
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Activation of Cav1.2 and BKCa is involved in the downregulation of caffeine-induced contraction in mice mesenteric arteries. Life Sci 2019; 231:116555. [DOI: 10.1016/j.lfs.2019.116555] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 06/07/2019] [Accepted: 06/08/2019] [Indexed: 01/05/2023]
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17
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BK channel clustering is required for normal behavioral alcohol sensitivity in C. elegans. Sci Rep 2019; 9:10224. [PMID: 31308408 PMCID: PMC6629859 DOI: 10.1038/s41598-019-46615-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Accepted: 07/02/2019] [Indexed: 02/05/2023] Open
Abstract
The large conductance, calcium- and voltage-activated potassium channel, known as the BK channel, is one of the central proteins that mediate alcohol intoxication and tolerance across species. Although ethanol targets BK channels through direct interaction, how ethanol-mediated BK channel activation causes behavioral intoxication is poorly understood. In. C. elegans, loss of function in SLO-1, the BK channel ortholog, confers profound ethanol resistance in movement and egg-laying behaviors. Here, we show that depletion of SLO-1 channels clustered at the active zones with no change in the overall channel expression level results in locomotory resistance to the intoxicating effect of ethanol, equivalent to that of slo-1 loss-of-function mutants. Likewise, depletion of clustered SLO-1 channels in the sarcolemma and neurons leads to ethanol-resistant egg-laying behavior. By contrast, reduction in the overall SLO-1 channel level by over 70% causes only moderate ethanol resistance in movement, and minimal, if any, resistance in egg laying. Our findings strongly suggest that behavioral ethanol sensitivity is conferred by local, but not global, depression of excitability via clustered BK channels. Given that clustered BK channels are functionally coupled to, and localize near, calcium channels, ethanol may mediate its behavioral effects by targeting BK channels and their coupled calcium channels.
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18
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Miner K, Labitzke K, Liu B, Wang P, Henckels K, Gaida K, Elliott R, Chen JJ, Liu L, Leith A, Trueblood E, Hensley K, Xia XZ, Homann O, Bennett B, Fiorino M, Whoriskey J, Yu G, Escobar S, Wong M, Born TL, Budelsky A, Comeau M, Smith D, Phillips J, Johnston JA, McGivern JG, Weikl K, Powers D, Kunzelmann K, Mohn D, Hochheimer A, Sullivan JK. Drug Repurposing: The Anthelmintics Niclosamide and Nitazoxanide Are Potent TMEM16A Antagonists That Fully Bronchodilate Airways. Front Pharmacol 2019; 10:51. [PMID: 30837866 PMCID: PMC6382696 DOI: 10.3389/fphar.2019.00051] [Citation(s) in RCA: 87] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Accepted: 01/18/2019] [Indexed: 01/21/2023] Open
Abstract
There is an unmet need in severe asthma where approximately 40% of patients exhibit poor β-agonist responsiveness, suffer daily symptoms and show frequent exacerbations. Antagonists of the Ca2+-activated Cl- channel, TMEM16A, offers a new mechanism to bronchodilate airways and block the multiple contractiles operating in severe disease. To identify TMEM16A antagonists we screened a library of ∼580,000 compounds. The anthelmintics niclosamide, nitazoxanide, and related compounds were identified as potent TMEM16A antagonists that blocked airway smooth muscle depolarization and contraction. To evaluate whether TMEM16A antagonists resist use- and inflammatory-desensitization pathways limiting β-agonist action, we tested their efficacy under harsh conditions using maximally contracted airways or airways pretreated with a cytokine cocktail. Stunningly, TMEM16A antagonists fully bronchodilated airways, while the β-agonist isoproterenol showed only partial effects. Thus, antagonists of TMEM16A and repositioning of niclosamide and nitazoxanide represent an important additional treatment for patients with severe asthma and COPD that is poorly controlled with existing therapies. It is of note that drug repurposing has also attracted wide interest in niclosamide and nitazoxanide as a new treatment for cancer and infectious disease. For the first time we identify TMEM16A as a molecular target for these drugs and thus provide fresh insights into their mechanism for the treatment of these disorders in addition to respiratory disease.
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Affiliation(s)
- Kent Miner
- Department of Inflammation Research, Amgen Inc., Thousand Oaks, CA, United States
| | - Katja Labitzke
- Department of Therapeutic Discovery, Amgen Inc., Regensburg, Germany
| | - Benxian Liu
- Department of Inflammation Research, Amgen Inc., Thousand Oaks, CA, United States
| | - Paul Wang
- Department of Therapeutic Discovery, Amgen Inc., Thousand Oaks, CA, United States
| | - Kathryn Henckels
- Department of Inflammation Research, Amgen Inc., Thousand Oaks, CA, United States
| | - Kevin Gaida
- Department of Inflammation Research, Amgen Inc., Thousand Oaks, CA, United States
| | - Robin Elliott
- Department of Inflammation Research, Amgen Inc., Thousand Oaks, CA, United States
| | - Jian Jeffrey Chen
- Department of Medicinal Chemistry, Amgen Inc., Thousand Oaks, CA, United States
| | - Longbin Liu
- Department of Medicinal Chemistry, Amgen Inc., Thousand Oaks, CA, United States
| | - Anh Leith
- Department of Inflammation Research, Amgen Inc., Seattle, WA, United States
| | - Esther Trueblood
- Department of Comparative Biology and Safety Sciences, Amgen Inc., Seattle, WA, United States
- Department of Comparative Biology and Safety Sciences, Amgen Inc., Thousand Oaks, CA, United States
- Department of Comparative Biology and Safety Sciences, Amgen Inc., South San Francisco, CA, United States
| | - Kelly Hensley
- Department of Comparative Biology and Safety Sciences, Amgen Inc., Seattle, WA, United States
- Department of Comparative Biology and Safety Sciences, Amgen Inc., Thousand Oaks, CA, United States
- Department of Comparative Biology and Safety Sciences, Amgen Inc., South San Francisco, CA, United States
| | - Xing-Zhong Xia
- Department of Inflammation Research, Amgen Inc., Thousand Oaks, CA, United States
| | - Oliver Homann
- Genome Analysis Unit, Amgen Inc., South San Francisco, CA, United States
| | - Brian Bennett
- Department of Inflammation Research, Amgen Inc., Thousand Oaks, CA, United States
| | - Mike Fiorino
- Department of Inflammation Research, Amgen Inc., Thousand Oaks, CA, United States
| | - John Whoriskey
- Department of Inflammation Research, Amgen Inc., Thousand Oaks, CA, United States
| | - Gang Yu
- Department of Inflammation Research, Amgen Inc., Thousand Oaks, CA, United States
| | - Sabine Escobar
- Department of Inflammation Research, Amgen Inc., Seattle, WA, United States
| | - Min Wong
- Department of Inflammation Research, Amgen Inc., Thousand Oaks, CA, United States
| | - Teresa L. Born
- Department of Inflammation Research, Amgen Inc., Seattle, WA, United States
| | - Alison Budelsky
- Department of Inflammation Research, Amgen Inc., Seattle, WA, United States
| | - Mike Comeau
- Department of Inflammation Research, Amgen Inc., Seattle, WA, United States
| | - Dirk Smith
- Department of Inflammation Research, Amgen Inc., Seattle, WA, United States
| | - Jonathan Phillips
- Department of Inflammation Research, Amgen Inc., Thousand Oaks, CA, United States
| | - James A. Johnston
- Department of Inflammation Research, Amgen Inc., Thousand Oaks, CA, United States
| | - Joseph G. McGivern
- Department of Therapeutic Discovery, Amgen Inc., Thousand Oaks, CA, United States
| | - Kerstin Weikl
- Department of Therapeutic Discovery, Amgen Inc., Regensburg, Germany
| | - David Powers
- Department of Therapeutic Discovery, Amgen Inc., Thousand Oaks, CA, United States
| | - Karl Kunzelmann
- Institut für Physiologie, Universität Regensburg, Regensburg, Germany
| | - Deanna Mohn
- Department of Inflammation Research, Amgen Inc., Thousand Oaks, CA, United States
| | | | - John K. Sullivan
- Department of Inflammation Research, Amgen Inc., Thousand Oaks, CA, United States
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19
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Mitrokhin V, Filatova T, Shim A, Bilichenko A, Abramochkin D, Kamkin A, Mladenov M. L-type Ca2+ channels’ involvement in IFN-γ-induced signaling in rat ventricular cardiomyocytes. J Physiol Biochem 2019; 75:109-115. [DOI: 10.1007/s13105-019-00662-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Accepted: 01/22/2019] [Indexed: 12/31/2022]
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20
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Abstract
Ca2+- and voltage-gated K+ channels of large conductance (BK channels) are expressed in a diverse variety of both excitable and inexcitable cells, with functional properties presumably uniquely calibrated for the cells in which they are found. Although some diversity in BK channel function, localization, and regulation apparently arises from cell-specific alternative splice variants of the single pore-forming α subunit ( KCa1.1, Kcnma1, Slo1) gene, two families of regulatory subunits, β and γ, define BK channels that span a diverse range of functional properties. We are just beginning to unravel the cell-specific, physiological roles served by BK channels of different subunit composition.
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Affiliation(s)
- Vivian Gonzalez-Perez
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA;
| | - Christopher J Lingle
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA;
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21
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Drumm BT, Hennig GW, Baker SA, Sanders KM. Applications of Spatio-temporal Mapping and Particle Analysis Techniques to Quantify Intracellular Ca2+ Signaling In Situ. J Vis Exp 2019. [PMID: 30663707 DOI: 10.3791/58989] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Ca2+ imaging of isolated cells or specific types of cells within intact tissues often reveals complex patterns of Ca2+ signaling. This activity requires careful and in-depth analyses and quantification to capture as much information about the underlying events as possible. Spatial, temporal and intensity parameters intrinsic to Ca2+ signals such as frequency, duration, propagation, velocity and amplitude may provide some biological information required for intracellular signalling. High-resolution Ca2+ imaging typically results in the acquisition of large data files that are time consuming to process in terms of translating the imaging information into quantifiable data, and this process can be susceptible to human error and bias. Analysis of Ca2+ signals from cells in situ typically relies on simple intensity measurements from arbitrarily selected regions of interest (ROI) within a field of view (FOV). This approach ignores much of the important signaling information contained in the FOV. Thus, in order to maximize recovery of information from such high-resolution recordings obtained with Ca2+dyes or optogenetic Ca2+ imaging, appropriate spatial and temporal analysis of the Ca2+ signals is required. The protocols outlined in this paper will describe how a high volume of data can be obtained from Ca2+ imaging recordings to facilitate more complete analysis and quantification of Ca2+ signals recorded from cells using a combination of spatiotemporal map (STM)-based analysis and particle-based analysis. The protocols also describe how different patterns of Ca2+ signaling observed in different cell populations in situ can be analyzed appropriately. For illustration, the method will examine Ca2+ signaling in a specialized population of cells in the small intestine, interstitial cells of Cajal (ICC), using GECIs.
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Affiliation(s)
- Bernard T Drumm
- Department of Physiology and Cell Biology, University of Nevada Reno School of Medicine;
| | - Grant W Hennig
- Department of Pharmacology, The Robert Larner, M.D. College of Medicine, University of Vermont
| | - Salah A Baker
- Department of Physiology and Cell Biology, University of Nevada Reno School of Medicine
| | - Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada Reno School of Medicine
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22
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Au DT, Ying Z, Hernández-Ochoa EO, Fondrie WE, Hampton B, Migliorini M, Galisteo R, Schneider MF, Daugherty A, Rateri DL, Strickland DK, Muratoglu SC. LRP1 (Low-Density Lipoprotein Receptor-Related Protein 1) Regulates Smooth Muscle Contractility by Modulating Ca 2+ Signaling and Expression of Cytoskeleton-Related Proteins. Arterioscler Thromb Vasc Biol 2018; 38:2651-2664. [PMID: 30354243 PMCID: PMC6214382 DOI: 10.1161/atvbaha.118.311197] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 09/12/2018] [Indexed: 01/12/2023]
Abstract
Objective- Mutations affecting contractile-related proteins in the ECM (extracellular matrix), microfibrils, or vascular smooth muscle cells can predispose the aorta to aneurysms. We reported previously that the LRP1 (low-density lipoprotein receptor-related protein 1) maintains vessel wall integrity, and smLRP1-/- mice exhibited aortic dilatation. The current study focused on defining the mechanisms by which LRP1 regulates vessel wall function and integrity. Approach and Results- Isometric contraction assays demonstrated that vasoreactivity of LRP1-deficient aortic rings was significantly attenuated when stimulated with vasoconstrictors, including phenylephrine, thromboxane receptor agonist U-46619, increased potassium, and L-type Ca2+ channel ligand FPL-64176. Quantitative proteomics revealed proteins involved in actin polymerization and contraction were significantly downregulated in aortas of smLRP1-/- mice. However, studies with calyculin A indicated that although aortic muscle from smLRP1-/- mice can contract in response to calyculin A, a role for LRP1 in regulating the contractile machinery is not revealed. Furthermore, intracellular calcium imaging experiments identified defects in calcium release in response to a RyR (ryanodine receptor) agonist in smLRP1-/- aortic rings and cultured vascular smooth muscle cells. Conclusions- These results identify a critical role for LRP1 in modulating vascular smooth muscle cell contraction by regulating calcium signaling events that potentially protect against aneurysm development.
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MESH Headings
- Actin Cytoskeleton/drug effects
- Actin Cytoskeleton/genetics
- Actin Cytoskeleton/metabolism
- Actin Cytoskeleton/ultrastructure
- Animals
- Aorta/metabolism
- Calcium Channels/genetics
- Calcium Channels/metabolism
- Calcium Signaling/drug effects
- Cytoskeletal Proteins/genetics
- Cytoskeletal Proteins/metabolism
- Female
- Gene Expression Regulation
- Low Density Lipoprotein Receptor-Related Protein-1
- Male
- Mice, Knockout
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Muscle, Smooth, Vascular/ultrastructure
- Receptors, LDL/deficiency
- Receptors, LDL/genetics
- Receptors, LDL/metabolism
- Ryanodine Receptor Calcium Release Channel/genetics
- Ryanodine Receptor Calcium Release Channel/metabolism
- Tissue Culture Techniques
- Tumor Suppressor Proteins/deficiency
- Tumor Suppressor Proteins/genetics
- Tumor Suppressor Proteins/metabolism
- Vasoconstriction/drug effects
- Vasoconstrictor Agents/pharmacology
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Affiliation(s)
- Dianaly T. Au
- Center for Vascular and Inflammatory Diseases, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Zhekang Ying
- Department of Medicine Cardiology Division, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Erick O. Hernández-Ochoa
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - William E. Fondrie
- Center for Vascular and Inflammatory Diseases, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Brian Hampton
- Center for Vascular and Inflammatory Diseases, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Mary Migliorini
- Center for Vascular and Inflammatory Diseases, University of Maryland School of Medicine, Baltimore, MD 21201, USA
- Saha Cardiovascular Research Center and Department of Physiology, University of Kentucky, Lexington, KY 40536, USA
| | - Rebeca Galisteo
- Center for Vascular and Inflammatory Diseases, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Martin F. Schneider
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Alan Daugherty
- Saha Cardiovascular Research Center and Department of Physiology, University of Kentucky, Lexington, KY 40536, USA
| | - Debra L. Rateri
- Saha Cardiovascular Research Center and Department of Physiology, University of Kentucky, Lexington, KY 40536, USA
| | - Dudley K. Strickland
- Center for Vascular and Inflammatory Diseases, University of Maryland School of Medicine, Baltimore, MD 21201, USA
- Department of Surgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Selen C. Muratoglu
- Center for Vascular and Inflammatory Diseases, University of Maryland School of Medicine, Baltimore, MD 21201, USA
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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23
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Zhou Y, Xia XM, Lingle CJ. BK channel inhibition by strong extracellular acidification. eLife 2018; 7:38060. [PMID: 29963986 PMCID: PMC6054526 DOI: 10.7554/elife.38060] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Accepted: 07/01/2018] [Indexed: 12/24/2022] Open
Abstract
Mammalian BK-type voltage- and Ca2+-dependent K+ channels are found in a wide range of cells and intracellular organelles. Among different loci, the composition of the extracellular microenvironment, including pH, may differ substantially. For example, it has been reported that BK channels are expressed in lysosomes with their extracellular side facing the strongly acidified lysosomal lumen (pH ~4.5). Here we show that BK activation is strongly and reversibly inhibited by extracellular H+, with its conductance-voltage relationship shifted by more than +100 mV at pHO 4. Our results reveal that this inhibition is mainly caused by H+ inhibition of BK voltage-sensor (VSD) activation through three acidic residues on the extracellular side of BK VSD. Given that these key residues (D133, D147, D153) are highly conserved among members in the voltage-dependent cation channel superfamily, the mechanism underlying BK inhibition by extracellular acidification might also be applicable to other members in the family.
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Affiliation(s)
- Yu Zhou
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, United States
| | - Xiao-Ming Xia
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, United States
| | - Christopher J Lingle
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, United States
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24
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Baylie R, Ahmed M, Bonev AD, Hill-Eubanks DC, Heppner TJ, Nelson MT, Greenstein AS. Lack of direct effect of adiponectin on vascular smooth muscle cell BK Ca channels or Ca 2+ signaling in the regulation of small artery pressure-induced constriction. Physiol Rep 2018; 5:5/16/e13337. [PMID: 28830977 PMCID: PMC5582259 DOI: 10.14814/phy2.13337] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 05/18/2017] [Accepted: 05/20/2017] [Indexed: 12/23/2022] Open
Abstract
The aim of this study was to investigate mechanisms by which adiponectin influences vascular Ca2+ signaling, K+ channel activity and thus contractile tone of small arteries. Vasodilation to adiponectin was studied in mesenteric resistance arteries constricted with intraluminal pressure. Ca2+ signals were characterized using high speed confocal microscopy of intact arteries. Patch clamp investigated the effect of adiponectin on individual VSMC potassium (K+) channel currents. Adiponectin dilated arteries constricted with pressure‐induced tone by approximately 5% and the induced vasodilation was only transient. The dilation to adiponectin was reduced by pharmacological interruption of the Ca2+ spark/large conductance activated K+ (BK) channel pathway but from a physiological perspective, interpretation of the data was limited by the small effect. Neither Adiponectin nor the presence of intact perivascular adipose tissue (PVAT) influenced Ca2+ spark or Ca2+ wave frequency or characteristics. Studied using a perforated patch approach, Adiponectin marginally increased current through the VSMC BK channel but this effect was lost using the whole cell technique with dialysis of the cytoplasm. Adiponectin did not change the frequency or amplitude of Ca2+ spark‐induced transient outward currents (STOC). Overall, our study shows that Adiponectin induces only a small and transient dilation of pressure constricted mesenteric arteries. This vasodilatory effect is likely to be independent of Ca2+ sparks or direct BK channel activation.
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Affiliation(s)
- Rachael Baylie
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Majid Ahmed
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Adrian D Bonev
- Department of Pharmacology, University of Vermont, Burlington, Vermont
| | | | - Thomas J Heppner
- Department of Pharmacology, University of Vermont, Burlington, Vermont
| | - Mark T Nelson
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK.,Department of Pharmacology, University of Vermont, Burlington, Vermont
| | - Adam S Greenstein
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
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25
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Pritchard HAT, Gonzales AL, Pires PW, Drumm BT, Ko EA, Sanders KM, Hennig GW, Earley S. Microtubule structures underlying the sarcoplasmic reticulum support peripheral coupling sites to regulate smooth muscle contractility. Sci Signal 2017; 10:eaan2694. [PMID: 28928237 PMCID: PMC6328376 DOI: 10.1126/scisignal.aan2694] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Junctional membrane complexes facilitate excitation-contraction coupling in skeletal and cardiac muscle cells by forming subcellular invaginations that maintain close (≤20 nm) proximity of ryanodine receptors (RyRs) on the sarcoplasmic reticulum (SR) with voltage-dependent Ca2+ channels in the plasma membrane. In fully differentiated smooth muscle cells, junctional membrane complexes occur as distributed sites of peripheral coupling. We investigated the role of the cytoskeleton in maintaining peripheral coupling and associated Ca2+ signaling networks within native smooth muscle cells of mouse and rat cerebral arteries. Using live-cell confocal and superresolution microscopy, we found that the tight interactions between the SR and the plasma membrane in these cells relied on arching microtubule structures present at the periphery of smooth muscle cells and were independent of the actin cytoskeleton. Loss of peripheral coupling associated with microtubule depolymerization altered the spatiotemporal properties of localized Ca2+ sparks generated by the release of Ca2+ through type 2 RyRs (RyR2s) on the SR and decreased the number of sites of colocalization between RyR2s and large-conductance Ca2+-activated K+ (BK) channels. The reduced BK channel activity associated with the loss of SR-plasma membrane interactions was accompanied by increased pressure-induced constriction of cerebral resistance arteries. We conclude that microtubule structures maintain peripheral coupling in contractile smooth muscle cells, which is crucial for the regulation of contractility and cerebral vascular tone.
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Affiliation(s)
- Harry A T Pritchard
- Department of Pharmacology, Center for Cardiovascular Research, University of Nevada, Reno School of Medicine, Reno, NV 89557, USA
| | - Albert L Gonzales
- Department of Pharmacology, University of Vermont, Burlington, VT 05405, USA
| | - Paulo W Pires
- Department of Pharmacology, Center for Cardiovascular Research, University of Nevada, Reno School of Medicine, Reno, NV 89557, USA
| | - Bernard T Drumm
- Department of Physiology and Cell Biology, Center for Cardiovascular Research, University of Nevada, Reno School of Medicine, Reno, NV 89557, USA
| | - Eun A Ko
- Department of Physiology and Cell Biology, Center for Cardiovascular Research, University of Nevada, Reno School of Medicine, Reno, NV 89557, USA
| | - Kenton M Sanders
- Department of Physiology and Cell Biology, Center for Cardiovascular Research, University of Nevada, Reno School of Medicine, Reno, NV 89557, USA
| | - Grant W Hennig
- Department of Pharmacology, University of Vermont, Burlington, VT 05405, USA
| | - Scott Earley
- Department of Pharmacology, Center for Cardiovascular Research, University of Nevada, Reno School of Medicine, Reno, NV 89557, USA.
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26
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Drumm BT, Hennig GW, Battersby MJ, Cunningham EK, Sung TS, Ward SM, Sanders KM, Baker SA. Clustering of Ca 2+ transients in interstitial cells of Cajal defines slow wave duration. J Gen Physiol 2017; 149:703-725. [PMID: 28592421 PMCID: PMC5496507 DOI: 10.1085/jgp.201711771] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Accepted: 05/02/2017] [Indexed: 12/13/2022] Open
Abstract
Electrical slow waves in the small intestine are generated by pacemaker cells called interstitial cells of Cajal. Drumm et al. record clusters of Ca2+ transients in these cells that are entrained by voltage-dependent Ca2+ entry and which define the duration of the electrical slow waves. Interstitial cells of Cajal (ICC) in the myenteric plexus region (ICC-MY) of the small intestine are pacemakers that generate rhythmic depolarizations known as slow waves. Slow waves depend on activation of Ca2+-activated Cl− channels (ANO1) in ICC, propagate actively within networks of ICC-MY, and conduct to smooth muscle cells where they generate action potentials and phasic contractions. Thus, mechanisms of Ca2+ regulation in ICC are fundamental to the motor patterns of the bowel. Here, we characterize the nature of Ca2+ transients in ICC-MY within intact muscles, using mice expressing a genetically encoded Ca2+ sensor, GCaMP3, in ICC. Ca2+ transients in ICC-MY display a complex firing pattern caused by localized Ca2+ release events arising from multiple sites in cell somata and processes. Ca2+ transients are clustered within the time course of slow waves but fire asynchronously during these clusters. The durations of Ca2+ transient clusters (CTCs) correspond to slow wave durations (plateau phase). Simultaneous imaging and intracellular electrical recordings revealed that the upstroke depolarization of slow waves precedes clusters of Ca2+ transients. Summation of CTCs results in relatively uniform Ca2+ responses from one slow wave to another. These Ca2+ transients are caused by Ca2+ release from intracellular stores and depend on ryanodine receptors as well as amplification from IP3 receptors. Reduced extracellular Ca2+ concentrations and T-type Ca2+ channel blockers decreased the number of firing sites and firing probability of Ca2+ transients. In summary, the fundamental electrical events of small intestinal muscles generated by ICC-MY depend on asynchronous firing of Ca2+ transients from multiple intracellular release sites. These events are organized into clusters by Ca2+ influx through T-type Ca2+ channels to sustain activation of ANO1 channels and generate the plateau phase of slow waves.
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Affiliation(s)
- Bernard T Drumm
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV
| | - Grant W Hennig
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV
| | - Matthew J Battersby
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV
| | - Erin K Cunningham
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV
| | - Tae Sik Sung
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV
| | - Sean M Ward
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV
| | - Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV
| | - Salah A Baker
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV
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27
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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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28
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Zhang G, Geng Y, Jin Y, Shi J, McFarland K, Magleby KL, Salkoff L, Cui J. Deletion of cytosolic gating ring decreases gate and voltage sensor coupling in BK channels. J Gen Physiol 2017; 149:373-387. [PMID: 28196879 PMCID: PMC5339509 DOI: 10.1085/jgp.201611646] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2016] [Revised: 10/28/2016] [Accepted: 12/28/2016] [Indexed: 12/26/2022] Open
Abstract
Both cellular depolarization and intracellular Ca2+ can gate open large conductance Ca2+-activated K+ channels. Zhang et al. show that the intracellular gating ring, which forms the Ca2+-sensing machinery of the channel, is also required for activated voltage sensors to effectively gate open the pore. Large conductance Ca2+-activated K+ channels (BK channels) gate open in response to both membrane voltage and intracellular Ca2+. The channel is formed by a central pore-gate domain (PGD), which spans the membrane, plus transmembrane voltage sensors and a cytoplasmic gating ring that acts as a Ca2+ sensor. How these voltage and Ca2+ sensors influence the common activation gate, and interact with each other, is unclear. A previous study showed that a BK channel core lacking the entire cytoplasmic gating ring (Core-MT) was devoid of Ca2+ activation but retained voltage sensitivity (Budelli et al. 2013. Proc. Natl. Acad. Sci. USA. http://dx.doi.org/10.1073/pnas.1313433110). In this study, we measure voltage sensor activation and pore opening in this Core-MT channel over a wide range of voltages. We record gating currents and find that voltage sensor activation in this truncated channel is similar to WT but that the coupling between voltage sensor activation and gating of the pore is reduced. These results suggest that the gating ring, in addition to being the Ca2+ sensor, enhances the effective coupling between voltage sensors and the PGD. We also find that removal of the gating ring alters modulation of the channels by the BK channel’s β1 and β2 subunits.
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Affiliation(s)
- Guohui Zhang
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, Cardiac Bioelectricity and Arrhythmia Center, Washington University, St. Louis, MO 63130
| | - Yanyan Geng
- Department of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, FL 33136
| | - Yakang Jin
- Department of Pharmacology, Soochow University College of Pharmaceutical Sciences, Suzhou 215123, China
| | - Jingyi Shi
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, Cardiac Bioelectricity and Arrhythmia Center, Washington University, St. Louis, MO 63130
| | - Kelli McFarland
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, Cardiac Bioelectricity and Arrhythmia Center, Washington University, St. Louis, MO 63130
| | - Karl L Magleby
- Department of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, FL 33136
| | - Lawrence Salkoff
- Department of Anatomy and Neurobiology (Department of Neuroscience), Washington University School of Medicine in St. Louis, St. Louis, MO 63110.,Department of Genetics, Washington University School of Medicine in St. Louis, St. Louis, MO 63110
| | - Jianmin Cui
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, Cardiac Bioelectricity and Arrhythmia Center, Washington University, St. Louis, MO 63130 .,Department of Pharmacology, Soochow University College of Pharmaceutical Sciences, Suzhou 215123, China
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29
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Niazmand S, Fereidouni E, Mahmoudabady M, Hosseini M. Teucrium polium-induced Vasorelaxation Mediated by Endothelium-dependent and Endothelium-independent Mechanisms in Isolated Rat Thoracic Aorta. Pharmacognosy Res 2017; 9:372-377. [PMID: 29263631 PMCID: PMC5717790 DOI: 10.4103/pr.pr_140_16] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Objective: There are some reports on hypotensive and antispasmodic effects of Teucrium polium L. (Lamiaceae) (TP). Subjects and Methods: The activity of different concentrations of TP extract (1, 2, 4 and 8 mg/ml) was evaluated on contractile responses of isolated aorta to potassium chloride (KCl) and phenylephrine (PE). Results: The cumulative concentrations of the extract induced a concentration-dependent relaxation in the aorta precontracted by PE and KCl. Extract-induced vasorelaxations in denuded aortic rings precontracted by PE and KCl at lower concentrations were considerably less than intact aortic rings, but this effect was significantly more at concentrations of 4 mg/ml for PE-, 4 and 8 mg/ml for KCl-induced contractions. All the extract concentrations (except 1 mg/ml) significantly relaxed PE-induced contraction in the presence of NG-nitro-L-arginine methyl ester. Indomethacin reduced effectively extract-induced vasorelaxation at 1 and 2 mg/ml. The extract reduced PE- and KCl-induced contractions in the presence of cumulative calcium concentrations and after incubation with diltiazem; this vasorelaxant effect of TP was decreased. TP-induced relaxation was inhibited by heparin, ruthenium red, glibenclamide, and tetraethylammonium, but 4-aminopyridine had no effect on TP-induced relaxation. Conclusion: TP extract has vasorelaxant effect on isolated rat thoracic aorta which mediated by endothelium-dependent and endothelium-independent mechanisms. The relaxation mainly was mediated by inhibition of calcium influx in vascular smooth muscle cells. It seems that the vasorelaxant effect of extract at lower concentrations was mediated by nitric oxide and prostacyclin. SUMMARY The vasodilatory effect of Teucrium polium L. was mediated by several mechanisms. First: Teucrium polium L. inhibited receptor operated ROCC and VDCC. Second: Teucrium polium L. also inhibited KATP and KCa channels. Third: Teucrium polium L. blocked IP3 receptor and reduced the release of calcium from intracellular source. Forth: Teucrium polium L. increased the release on NO and PGI2 from endothelial cells.
Abbreviations Used: ROCC: Receptor operated calcium channels, VDCC: Voltage dependent calcium channels, PLC: Phospholipase C, IP3: 1,4,5 triphosphate inositol, IP3R: IP3 receptors, SR: sarcoplasmic reticulum, RYR: ryanodine receptors, K+ATP: ATP-sensitive potassium channel, K+Ca: Calcium-activated potassium channel, cAMP: Cyclic adenosine monophosphate, cGMP: Cyclic guanosine monophosphate, PGI2: Prostaglandin I2, NO: Nitric oxide
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Affiliation(s)
- Saeed Niazmand
- Cardiovascular Research Center, Mashhad University of Medical Sciences, Mashhad, Iran.,Department of Physiology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Elahe Fereidouni
- Department of Physiology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Maryam Mahmoudabady
- Department of Physiology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.,Neurogenic Inflammation Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Mahmoud Hosseini
- Department of Physiology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.,Neurocognitive Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
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30
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Di Mise A, Wang YX, Zheng YM. Role of Transcription Factors in Pulmonary Artery Smooth Muscle Cells: An Important Link to Hypoxic Pulmonary Hypertension. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 967:13-32. [PMID: 29047078 DOI: 10.1007/978-3-319-63245-2_2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Hypoxia, namely a lack of oxygen in the blood, induces pulmonary vasoconstriction and vasoremodeling, which serve as essential pathologic factors leading to pulmonary hypertension (PH). The underlying molecular mechanisms are uncertain; however, pulmonary artery smooth muscle cells (PASMCs) play an essential role in hypoxia-induced pulmonary vasoconstriction, vasoremodeling, and PH. Hypoxia causes oxidative damage to DNAs, proteins, and lipids. This damage (oxidative stress) modulates the activity of ion channels and elevates the intracellular calcium concentration ([Ca2+]i, Ca2+ signaling) of PASMCs. The oxidative stress and increased Ca2+ signaling mutually interact with each other, and synergistically results in a variety of cellular responses. These responses include functional and structural abnormalities of mitochondria, sarcoplasmic reticulum, and nucleus; cell contraction, proliferation, migration, and apoptosis, as well as generation of vasoactive substances, inflammatory molecules, and growth factors that mediate the development of PH. A number of studies reveal that various transcription factors (TFs) play important roles in hypoxia-induced oxidative stress, disrupted PAMSC Ca2+ signaling and the development and progress of PH. It is believed that in the pathogenesis of PH, hypoxia facilitates these roles by mediating the expression of multiple genes. Therefore, the identification of specific genes and their transcription factors implicated in PH is necessary for the complete understanding of the underlying molecular mechanisms. Moreover, this identification may aid in the development of novel and effective therapeutic strategies for PH.
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Affiliation(s)
- Annarita Di Mise
- Department of Molecular & Cellular Physiology, Albany Medical College, 47 New Scotland Avenue, Albany, NY, 12208, USA
| | - Yong-Xiao Wang
- Department of Molecular & Cellular Physiology, Albany Medical College, 47 New Scotland Avenue, Albany, NY, 12208, USA.
| | - Yun-Min Zheng
- Department of Molecular & Cellular Physiology, Albany Medical College, 47 New Scotland Avenue, Albany, NY, 12208, USA.
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31
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Dai R, Wang T, Si X, Jia Y, Wang L, Yuan Y, Lin Q, Yang C. Vasodilatory effects and underlying mechanisms of the ethyl acetate extracts from Gastrodia elata. Can J Physiol Pharmacol 2016; 95:564-571. [PMID: 28177685 DOI: 10.1139/cjpp-2016-0407] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The objective of this study was to assess the ethyl acetate extracts of Gastrodia elata Blume (GEB) on vascular tone and the mechanisms involved. GEB was extracted with 95% EtOH followed by a further extraction with ethyl acetate. The effects of GEB and its ingredients on the isometric tensions of the aortic rings from rats were measured. The ethyl acetate extract of GEB induced a vasodilatory effect on rat aorta, which was partially dependent on endothelium. Four chemical compounds isolated from GEB were identified as 3,4-dihydroxybenzaldehyde (DB), 4-hydroxybenzaldehyde (HB), 4-methoxybenzyl alcohol (MA), and 4,4'-dihydroxydiphenyl methane (DM), respectively. All of these compounds induced vasodilatations, which were dependent on the endothelium to different degrees. After pretreatment with Nω-nitro-l-arginine methyl ester, indomethacin, or methylene blue, the vasodilatations induced by DB, HB, and MA were significantly decreased. In addition, the contractions of the rat aortic rings due to Ca2+ influx and intracellular Ca2+ release were also inhibited by DM. Furthermore, the administration of DB significantly enhanced the productions of nitric oxide (NO) and the activities of the endothelial NO synthase in aorta and in endothelial cells. Thus, GEB may play an important role in the amelioration of hypertension by modulating vascular tones.
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Affiliation(s)
- Rong Dai
- a Department of Pharmacology, Yunnan University of Traditional Chinese Medicine, Kunming 650500, P.R. China
| | - Ting Wang
- b Ethnic Drug Screening & Pharmacology Center, Key Laboratory of Chemistry in Ethnic Medicinal Resources, State Ethnic Affairs Commission & Ministry of Education, Yunnan Minzu University, Kunming 650500, P.R. China
| | - Xiaoqin Si
- a Department of Pharmacology, Yunnan University of Traditional Chinese Medicine, Kunming 650500, P.R. China
| | - Yuanyuan Jia
- a Department of Pharmacology, Yunnan University of Traditional Chinese Medicine, Kunming 650500, P.R. China
| | - Lili Wang
- a Department of Pharmacology, Yunnan University of Traditional Chinese Medicine, Kunming 650500, P.R. China
| | - Yan Yuan
- b Ethnic Drug Screening & Pharmacology Center, Key Laboratory of Chemistry in Ethnic Medicinal Resources, State Ethnic Affairs Commission & Ministry of Education, Yunnan Minzu University, Kunming 650500, P.R. China
| | - Qing Lin
- a Department of Pharmacology, Yunnan University of Traditional Chinese Medicine, Kunming 650500, P.R. China
| | - Cui Yang
- b Ethnic Drug Screening & Pharmacology Center, Key Laboratory of Chemistry in Ethnic Medicinal Resources, State Ethnic Affairs Commission & Ministry of Education, Yunnan Minzu University, Kunming 650500, P.R. China
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32
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Khavandi K, Baylie RA, Sugden SA, Ahmed M, Csato V, Eaton P, Hill-Eubanks DC, Bonev AD, Nelson MT, Greenstein AS. Pressure-induced oxidative activation of PKG enables vasoregulation by Ca2+ sparks and BK channels. Sci Signal 2016; 9:ra100. [PMID: 27729550 DOI: 10.1126/scisignal.aaf6625] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Activation of Ca2+-sensitive, large-conductance potassium (BK) channels in vascular smooth muscle cells (VSMCs) by local, ryanodine receptor-mediated Ca2+ signals (Ca2+ sparks) acts as a brake on pressure-induced (myogenic) vasoconstriction-a fundamental mechanism that regulates blood flow in small resistance arteries. We report that physiological intraluminal pressure within resistance arteries activated cGMP-dependent protein kinase (PKG) in VSMCs through oxidant-induced formation of an intermolecular disulfide bond between cysteine residues. Oxidant-activated PKG was required to trigger Ca2+ sparks, BK channel activity, and vasodilation in response to pressure. VSMCs from arteries from mice expressing a form of PKG that could not be activated by oxidants showed reduced Ca2+ spark frequency, and arterial preparations from these mice had decreased pressure-induced activation of BK channels. Thus, the absence of oxidative activation of PKG disabled the BK channel-mediated negative feedback regulation of vasoconstriction. Our results support the concept of a negative feedback control mechanism that regulates arterial diameter through mechanosensitive production of oxidants to activate PKG and enhance Ca2+ sparks.
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Affiliation(s)
- Kaivan Khavandi
- Institute of Cardiovascular Sciences, Faculty of Medical and Human Sciences, University of Manchester, Manchester Academic Health Sciences Center, Manchester, M13 9NT, UK.,King's College London, Cardiovascular Division, The British Heart Foundation Centre of Excellence, The Rayne Institute, Saint Thomas' Hospital, London, SE1 7EH, UK
| | - Rachael A Baylie
- Institute of Cardiovascular Sciences, Faculty of Medical and Human Sciences, University of Manchester, Manchester Academic Health Sciences Center, Manchester, M13 9NT, UK
| | - Sarah A Sugden
- Institute of Cardiovascular Sciences, Faculty of Medical and Human Sciences, University of Manchester, Manchester Academic Health Sciences Center, Manchester, M13 9NT, UK
| | - Majid Ahmed
- Institute of Cardiovascular Sciences, Faculty of Medical and Human Sciences, University of Manchester, Manchester Academic Health Sciences Center, Manchester, M13 9NT, UK.,Department of Pharmacology, University of Vermont, Vermont, 05405-0068, USA
| | - Viktoria Csato
- Institute of Cardiovascular Sciences, Faculty of Medical and Human Sciences, University of Manchester, Manchester Academic Health Sciences Center, Manchester, M13 9NT, UK.,Division of Clinical Physiology, Institute of Cardiology, Research Centre for Molecular Medicine, Faculty of Medicine, University of Debrecen, Debrecen 4012, Hungary
| | - Philip Eaton
- King's College London, Cardiovascular Division, The British Heart Foundation Centre of Excellence, The Rayne Institute, Saint Thomas' Hospital, London, SE1 7EH, UK
| | | | - Adrian D Bonev
- Department of Pharmacology, University of Vermont, Vermont, 05405-0068, USA
| | - Mark T Nelson
- Institute of Cardiovascular Sciences, Faculty of Medical and Human Sciences, University of Manchester, Manchester Academic Health Sciences Center, Manchester, M13 9NT, UK.,Department of Pharmacology, University of Vermont, Vermont, 05405-0068, USA
| | - Adam S Greenstein
- Institute of Cardiovascular Sciences, Faculty of Medical and Human Sciences, University of Manchester, Manchester Academic Health Sciences Center, Manchester, M13 9NT, UK
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33
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Jie L, Owens EA, Plante LA, Fang Z, Rensing DT, Moeller KD, Osei-Owusu P. RGS2 squelches vascular Gi/o and Gq signaling to modulate myogenic tone and promote uterine blood flow. Physiol Rep 2016; 4:4/2/e12692. [PMID: 26811058 PMCID: PMC4760385 DOI: 10.14814/phy2.12692] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Uterine artery blood flow (UABF) is critical to maintaining uterine perfusion in nonpregnant states and for uteroplacental delivery of nutrients and oxygen to the fetus during pregnancy. Impaired UABF is implicated in infertility and several pregnancy complications including fetal growth restriction, small for gestational age, and preeclampsia. The etiology of abnormal UABF is not known. Here, we determined whether deficiency or loss of RGS2, a GTPase-activating protein for Gq/11 and Gi/o class G proteins, affects UABF in nonpregnant mice. We used Doppler ultrasonography to assess UABF in wild type (WT), Rgs2 heterozygous (Rgs2+/-), and homozygous knockout (Rgs2-/-) mice. Video microscopy was used for ex vivo examination of uterine artery myogenic tone and fura-2 imaging for in vitro assessment of internal stores Ca(2+) release. We found that baseline UABF velocity was markedly decreased while impedance measured as resistive index (WT = 0.58 ± 0.04 vs. Rgs2-/- = 0.71 ± 0.03, P < 0.01) and pulsatile index (WT = 0.90 ± 0.06 vs. Rgs2-/- = 1.25 ± 0.11, P < 0.01) was increased in Rgs2-/- mice. Uterine artery tone was augmented in Rgs2+/- and Rgs2-/- mice, which was normalized to WT levels following Gi/o and Gq inactivation. Conversely, blockade of ryanodine receptors increased WT myogenic tone to RGS2 mutant levels. The data together indicate that RGS2 deficiency decreases UABF by increasing myogenic tone at least partly through prolonged G protein activation. Mutations that decrease vascular RGS2 expression may be a predisposition to decreased uterine blood flow. Targeting G protein signaling therefore might improve uterine and uteroplacental underperfusion disorders.
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Affiliation(s)
- Li Jie
- Department of Pharmacology & Physiology, Drexel University College of Medicine, Philadelphia, Pennsylvania Nanjing University of Traditional Chinese Medicine, Nanjing, Jiangsu, China
| | - Elizabeth A Owens
- Department of Pharmacology & Physiology, Drexel University College of Medicine, Philadelphia, Pennsylvania
| | - Lauren A Plante
- Department of Obstetrics & Gynecology, Drexel University College of Medicine, Philadelphia, Pennsylvania
| | - Zhuyuan Fang
- Jiangsu Hospital of Traditional Chinese Medicine, Nanjing, Jiangsu, China
| | - Derek T Rensing
- Department of Chemistry, Washington University, St. Louis, Missouri
| | - Kevin D Moeller
- Department of Chemistry, Washington University, St. Louis, Missouri
| | - Patrick Osei-Owusu
- Department of Pharmacology & Physiology, Drexel University College of Medicine, Philadelphia, Pennsylvania
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Potassium Channels in Regulation of Vascular Smooth Muscle Contraction and Growth. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2016; 78:89-144. [PMID: 28212804 DOI: 10.1016/bs.apha.2016.07.001] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Potassium channels importantly contribute to the regulation of vascular smooth muscle (VSM) contraction and growth. They are the dominant ion conductance of the VSM cell membrane and importantly determine and regulate membrane potential. Membrane potential, in turn, regulates the open-state probability of voltage-gated Ca2+ channels (VGCC), Ca2+ influx through VGCC, intracellular Ca2+, and VSM contraction. Membrane potential also affects release of Ca2+ from internal stores and the Ca2+ sensitivity of the contractile machinery such that K+ channels participate in all aspects of regulation of VSM contraction. Potassium channels also regulate proliferation of VSM cells through membrane potential-dependent and membrane potential-independent mechanisms. VSM cells express multiple isoforms of at least five classes of K+ channels that contribute to the regulation of contraction and cell proliferation (growth). This review will examine the structure, expression, and function of large conductance, Ca2+-activated K+ (BKCa) channels, intermediate-conductance Ca2+-activated K+ (KCa3.1) channels, multiple isoforms of voltage-gated K+ (KV) channels, ATP-sensitive K+ (KATP) channels, and inward-rectifier K+ (KIR) channels in both contractile and proliferating VSM cells.
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Gozalov A, Jansen-Olesen I, Klaerke D, Olesen J. Role of BKCa Channels in Cephalic Vasodilation Induced by CGRP, NO and Transcranial Electrical Stimulation In The Rat. Cephalalgia 2016; 27:1120-7. [PMID: 17714519 DOI: 10.1111/j.1468-2982.2007.01409.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Both calcitonin gene-related peptide (CGRP) and nitric oxide (NO) are potent vasodilators that have been shown to induce headache in migraine patients. Their antagonists are effective in the treatment of migraine attacks. In the present study, we hypothesize that vasodilation induced by the NO donor glyceryltrinitrate (GTN) or by CGRP is partially mediated via large conductance calcium-activated potassium (BKCa) channels. The effects of the BKCa channel selective inhibitor iberiotoxin on dural and pial vasodilation induced by CGRP, GTN and endogenously released CGRP by transcranial electrical stimulation (TES) were examined. Iberiotoxin significantly attenuated GTN-induced dural and pial artery dilation in vivo and in vitro, but had no effect on vasodilation induced by CGRP and TES. Our results show that GTN- but not CGRP-induced dural and pial vasodilation involves opening of BKCa channels in rat.
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Affiliation(s)
- A Gozalov
- Danish Headache Centre and Department of Neurology, and Department of Clinical Experimental Research, Glostrup Hospital, University of Copenhagen, DK-2600 Glostrup, Denmark.
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Atia J, McCloskey C, Shmygol AS, Rand DA, van den Berg HA, Blanks AM. Reconstruction of Cell Surface Densities of Ion Pumps, Exchangers, and Channels from mRNA Expression, Conductance Kinetics, Whole-Cell Calcium, and Current-Clamp Voltage Recordings, with an Application to Human Uterine Smooth Muscle Cells. PLoS Comput Biol 2016; 12:e1004828. [PMID: 27105427 PMCID: PMC4841602 DOI: 10.1371/journal.pcbi.1004828] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Accepted: 02/23/2016] [Indexed: 11/28/2022] Open
Abstract
Uterine smooth muscle cells remain quiescent throughout most of gestation, only generating spontaneous action potentials immediately prior to, and during, labor. This study presents a method that combines transcriptomics with biophysical recordings to characterise the conductance repertoire of these cells, the ‘conductance repertoire’ being the total complement of ion channels and transporters expressed by an electrically active cell. Transcriptomic analysis provides a set of potential electrogenic entities, of which the conductance repertoire is a subset. Each entity within the conductance repertoire was modeled independently and its gating parameter values were fixed using the available biophysical data. The only remaining free parameters were the surface densities for each entity. We characterise the space of combinations of surface densities (density vectors) consistent with experimentally observed membrane potential and calcium waveforms. This yields insights on the functional redundancy of the system as well as its behavioral versatility. Our approach couples high-throughput transcriptomic data with physiological behaviors in health and disease, and provides a formal method to link genotype to phenotype in excitable systems. We accurately predict current densities and chart functional redundancy. For example, we find that to evoke the observed voltage waveform, the BK channel is functionally redundant whereas hERG is essential. Furthermore, our analysis suggests that activation of calcium-activated chloride conductances by intracellular calcium release is the key factor underlying spontaneous depolarisations. A well-known problem in electrophysiologal modeling is that the parameters of the gating kinetics of the ion channels cannot be uniquely determined from observed behavior at the cellular level. One solution is to employ simplified “macroscopic” currents that mimic the behavior of aggregates of distinct entities at the protein level. The gating parameters of each channel or pump can be determined by studying it in isolation, leaving the general problem of finding the densities at which the channels occur in the plasma membrane. We propose an approach, which we apply to uterine smooth muscle cells, whereby we constrain the list of possible entities by means of transcriptomics and chart the indeterminacy of the problem in terms of the kernel of the corresponding linear transformation. A graphical representation of this kernel visualises the functional redundancy of the system. We show that the role of certain conductances can be fulfilled, or compensated for, by suitable combinations of other conductances; this is not always the case, and such “non-substitutable” conductances can be regarded as functionally non-redundant. Electrogenic entities belonging to the latter category are suitable putative clinical targets.
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Affiliation(s)
- Jolene Atia
- Division of Reproductive Health, Warwick Medical School, University of Warwick, Coventry, United Kingdom
| | - Conor McCloskey
- Division of Reproductive Health, Warwick Medical School, University of Warwick, Coventry, United Kingdom
| | - Anatoly S. Shmygol
- Division of Reproductive Health, Warwick Medical School, University of Warwick, Coventry, United Kingdom
| | | | | | - Andrew M. Blanks
- Division of Reproductive Health, Warwick Medical School, University of Warwick, Coventry, United Kingdom
- * E-mail:
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Brozovich FV, Nicholson CJ, Degen CV, Gao YZ, Aggarwal M, Morgan KG. Mechanisms of Vascular Smooth Muscle Contraction and the Basis for Pharmacologic Treatment of Smooth Muscle Disorders. Pharmacol Rev 2016; 68:476-532. [PMID: 27037223 PMCID: PMC4819215 DOI: 10.1124/pr.115.010652] [Citation(s) in RCA: 298] [Impact Index Per Article: 37.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The smooth muscle cell directly drives the contraction of the vascular wall and hence regulates the size of the blood vessel lumen. We review here the current understanding of the molecular mechanisms by which agonists, therapeutics, and diseases regulate contractility of the vascular smooth muscle cell and we place this within the context of whole body function. We also discuss the implications for personalized medicine and highlight specific potential target molecules that may provide opportunities for the future development of new therapeutics to regulate vascular function.
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Affiliation(s)
- F V Brozovich
- Department of Health Sciences, Boston University, Boston, Massachusetts (C.J.N., Y.Z.G., M.A., K.G.M.); Department of Medicine, Mayo Clinic, Rochester, Minnesota (F.V.B.); and Paracelsus Medical University Salzburg, Salzburg, Austria (C.V.D.)
| | - C J Nicholson
- Department of Health Sciences, Boston University, Boston, Massachusetts (C.J.N., Y.Z.G., M.A., K.G.M.); Department of Medicine, Mayo Clinic, Rochester, Minnesota (F.V.B.); and Paracelsus Medical University Salzburg, Salzburg, Austria (C.V.D.)
| | - C V Degen
- Department of Health Sciences, Boston University, Boston, Massachusetts (C.J.N., Y.Z.G., M.A., K.G.M.); Department of Medicine, Mayo Clinic, Rochester, Minnesota (F.V.B.); and Paracelsus Medical University Salzburg, Salzburg, Austria (C.V.D.)
| | - Yuan Z Gao
- Department of Health Sciences, Boston University, Boston, Massachusetts (C.J.N., Y.Z.G., M.A., K.G.M.); Department of Medicine, Mayo Clinic, Rochester, Minnesota (F.V.B.); and Paracelsus Medical University Salzburg, Salzburg, Austria (C.V.D.)
| | - M Aggarwal
- Department of Health Sciences, Boston University, Boston, Massachusetts (C.J.N., Y.Z.G., M.A., K.G.M.); Department of Medicine, Mayo Clinic, Rochester, Minnesota (F.V.B.); and Paracelsus Medical University Salzburg, Salzburg, Austria (C.V.D.)
| | - K G Morgan
- Department of Health Sciences, Boston University, Boston, Massachusetts (C.J.N., Y.Z.G., M.A., K.G.M.); Department of Medicine, Mayo Clinic, Rochester, Minnesota (F.V.B.); and Paracelsus Medical University Salzburg, Salzburg, Austria (C.V.D.)
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38
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Baker SA, Drumm BT, Saur D, Hennig GW, Ward SM, Sanders KM. Spontaneous Ca(2+) transients in interstitial cells of Cajal located within the deep muscular plexus of the murine small intestine. J Physiol 2016; 594:3317-38. [PMID: 26824875 DOI: 10.1113/jp271699] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Accepted: 01/24/2016] [Indexed: 01/13/2023] Open
Abstract
KEY POINTS Interstitial cells of Cajal at the level of the deep muscular plexus (ICC-DMP) in the small intestine generate spontaneous Ca(2+) transients that consist of localized Ca(2+) events and limited propagating Ca(2+) waves. Ca(2+) transients in ICC-DMP display variable characteristics: from discrete, highly localized Ca(2+) transients to regionalized Ca(2+) waves with variable rates of occurrence, amplitude, duration and spatial spread. Ca(2+) transients fired stochastically, with no cellular or multicellular rhythmic activity being observed. No correlation was found between the firing sites in adjacent cells. Ca(2+) transients in ICC-DMP are suppressed by the ongoing release of inhibitory neurotransmitter(s). Functional intracellular Ca(2+) stores are essential for spontaneous Ca(2+) transients, and the sarco/endoplasmic reticulum Ca(2+) -ATPase (SERCA) pump is necessary for maintenance of spontaneity. Ca(2+) release mechanisms involve both ryanodine receptors (RyRs) and inositol triphosphate receptors (InsP3 Rs). Release from these channels is interdependent. ICC express transcripts of multiple RyRs and InsP3 Rs, with Itpr1 and Ryr2 subtypes displaying the highest expression. ABSTRACT Interstitial cells of Cajal in the deep muscular plexus of the small intestine (ICC-DMP) are closely associated with varicosities of enteric motor neurons and generate responses contributing to neural regulation of intestinal motility. Responses of ICC-DMP are mediated by activation of Ca(2+) -activated Cl(-) channels; thus, Ca(2+) signalling is central to the behaviours of these cells. Confocal imaging was used to characterize the nature and mechanisms of Ca(2+) transients in ICC-DMP within intact jejunal muscles expressing a genetically encoded Ca(2+) indicator (GCaMP3) selectively in ICC. ICC-DMP displayed spontaneous Ca(2+) transients that ranged from discrete, localized events to waves that propagated over variable distances. The occurrence of Ca(2+) transients was highly variable, and it was determined that firing was stochastic in nature. Ca(2+) transients were tabulated in multiple cells within fields of view, and no correlation was found between the events in adjacent cells. TTX (1 μm) significantly increased the occurrence of Ca(2+) transients, suggesting that ICC-DMP contributes to the tonic inhibition conveyed by ongoing activity of inhibitory motor neurons. Ca(2+) transients were minimally affected after 12 min in Ca(2+) free solution, indicating these events do not depend immediately upon Ca(2+) influx. However, inhibitors of sarco/endoplasmic reticulum Ca(2+) -ATPase (SERCA) pump and blockers of inositol triphosphate receptor (InsP3 R) and ryanodine receptor (RyR) channels blocked ICC Ca(2+) transients. These data suggest an interdependence between RyR and InsP3 R in the generation of Ca(2+) transients. Itpr1 and Ryr2 were the dominant transcripts expressed by ICC. These findings provide the first high-resolution recording of the subcellular Ca(2+) dynamics that control the behaviour of ICC-DMP in situ.
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Affiliation(s)
- Salah A Baker
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA
| | - Bernard T Drumm
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA
| | - Dieter Saur
- II. Medizinische Klinik und Poliklinik, Klinikum rechts der Isar der TU München, München, Germany
| | - Grant W Hennig
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA
| | - Sean M Ward
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA
| | - Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA
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Chen YF, Wang C, Zhang R, Wang H, Ma R, Jin S, Xiang JZ, Tang Q. Tacrolimus inhibits vasoconstriction by increasing Ca(2+) sparks in rat aorta. ACTA ACUST UNITED AC 2016; 36:8-13. [PMID: 26838733 DOI: 10.1007/s11596-016-1534-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Revised: 12/29/2015] [Indexed: 11/26/2022]
Abstract
The present study attempted to test a novel hypothesis that Ca(2+) sparks play an important role in arterial relaxation induced by tacrolimus. Recorded with confocal laser scanning microscopy, tacrolimus (10 µmol/L) increased the frequency of Ca(2+) sparks, which could be reversed by ryanodine (10 µmol/L). Electrophysiological experiments revealed that tacrolimus (10 µmol/L) increased the large-conductance Ca(2+)-activated K(+) currents (BKCa) in rat aortic vascular smooth muscle cells (AVSMCs), which could be blocked by ryanodine (10 µmol/L). Furthermore, tacrolimus (10 and 50 µmol/L) reduced the contractile force induced by norepinephrine (NE) or KCl in aortic vascular smooth muscle in a concentration-dependent manner, which could be also significantly attenuated by iberiotoxin (100 nmol/L) and ryanodine (10 µmol/L) respectively. In conclusion, tacrolimus could indirectly activate BKCa currents by increasing Ca(2+) sparks released from ryanodine receptors, which inhibited the NE- or KCl-induced contraction in rat aorta.
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MESH Headings
- Animals
- Aorta/cytology
- Aorta/metabolism
- Aorta/physiology
- Calcium Signaling
- Cells, Cultured
- Large-Conductance Calcium-Activated Potassium Channels/metabolism
- Male
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Muscle, Smooth, Vascular/physiology
- Myocytes, Smooth Muscle/drug effects
- Myocytes, Smooth Muscle/metabolism
- Norepinephrine/pharmacology
- Rats
- Rats, Sprague-Dawley
- Ryanodine/pharmacology
- Tacrolimus/pharmacology
- Vasoconstriction
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Affiliation(s)
- Yu-Fang Chen
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Chen Wang
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Rui Zhang
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Huan Wang
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Rong Ma
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Si Jin
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Ji-Zhou Xiang
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Qiang Tang
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
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40
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Jiang M, Wan F, Wang F, Wu Q. Irisin relaxes mouse mesenteric arteries through endothelium-dependent and endothelium-independent mechanisms. Biochem Biophys Res Commun 2015; 468:832-6. [PMID: 26582714 DOI: 10.1016/j.bbrc.2015.11.040] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Accepted: 11/08/2015] [Indexed: 02/07/2023]
Abstract
Irisin, a newly discovered myokine, has been shown to produce modest weight loss and improve glucose intolerance in mice. The purpose of this study was to investigate the effects of irisin on vascular activity and the mechanisms involved. Experiments were performed on mouse mesenteric arteries. We demonstrated that irisin induced relaxation in mesenteric arteries with or without endothelium in a concentration-dependent manner. It was further demonstrated that the irisin-induced vasorelaxation effects on endothelium-intact mesenteric arteries were reduced by pretreatment with Nω-nitro-L-arginine methyl ester (L-NAME) or 1H-[1, 2, 4] oxadizolo [4, 3-a] quinoxalin-1-one (ODQ). However, pretreatment with indomethacin (INDO), a nonselective cyclooxygenase inhibitor did not modulate irisin-induced relaxation. In addition, the contraction due to extracellular Ca(2+) influx and intracellular Ca(2+) release was also inhibited by irisin. In summary, these results suggested that the endothelium-dependent relaxation of irisin is mediated by the nitric oxide (NO)-guanosine 3', 5'-cyclic phosphate (cGMP)-dependent pathway but not the prostaglandin I2 (PGI2)-cyclic adenosine monophosphate (cAMP)-dependent mechanism. Endothelium-independent relaxation may be depend on inhibiting Ca(2+) influx through blocking VDCCs and intracellular Ca(2+) release through both IP3R and RyR channels.
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Affiliation(s)
- Miao Jiang
- Experimental Animal Center, The Second Hospital of Shandong University, Jinan 250012, PR China
| | - Fangzhu Wan
- Department of Clinical Medicine, School of Medicine, Shandong University, Jinan 250012, PR China
| | - Fang Wang
- Experimental Animal Center, The Second Hospital of Shandong University, Jinan 250012, PR China
| | - Qi Wu
- Department of Clinical Medicine, School of Medicine, Shandong University, Jinan 250012, PR China.
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41
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Villalba N, Sonkusare SK, Longden TA, Tran TL, Sackheim AM, Nelson MT, Wellman GC, Freeman K. Traumatic brain injury disrupts cerebrovascular tone through endothelial inducible nitric oxide synthase expression and nitric oxide gain of function. J Am Heart Assoc 2015; 3:e001474. [PMID: 25527626 PMCID: PMC4338739 DOI: 10.1161/jaha.114.001474] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
BACKGROUND Traumatic brain injury (TBI) has been reported to increase the concentration of nitric oxide (NO) in the brain and can lead to loss of cerebrovascular tone; however, the sources, amounts, and consequences of excess NO on the cerebral vasculature are unknown. Our objective was to elucidate the mechanism of decreased cerebral artery tone after TBI. METHODS AND RESULTS Cerebral arteries were isolated from rats 24 hours after moderate fluid‐percussion TBI. Pressure‐induced increases in vasoconstriction (myogenic tone) and smooth muscle Ca2+ were severely blunted in cerebral arteries after TBI. However, myogenic tone and smooth muscle Ca2+ were restored by inhibition of NO synthesis or endothelium removal, suggesting that TBI increased endothelial NO levels. Live native cell NO, indexed by 4,5‐diaminofluorescein (DAF‐2 DA) fluorescence, was increased in endothelium and smooth muscle of cerebral arteries after TBI. Clamped concentrations of 20 to 30 nmol/L NO were required to simulate the loss of myogenic tone and increased (DAF‐2T) fluorescence observed following TBI. In comparison, basal NO in control arteries was estimated as 0.4 nmol/L. Consistent with TBI causing enhanced NO‐mediated vasodilation, inhibitors of guanylyl cyclase, protein kinase G, and large‐conductance Ca2+‐activated potassium (BK) channel restored function of arteries from animals with TBI. Expression of the inducible isoform of NO synthase was upregulated in cerebral arteries isolated from animals with TBI, and the inducible isoform of NO synthase inhibitor 1400W restored myogenic responses following TBI. CONCLUSIONS The mechanism of profound cerebral artery vasodilation after TBI is a gain of function in vascular NO production by 60‐fold over controls, resulting from upregulation of the inducible isoform of NO synthase in the endothelium.
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Affiliation(s)
- Nuria Villalba
- From the Departments of Pharmacology, University of Vermont, Burlington, VT
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42
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Cobb MM, Austin DC, Sack JT, Trimmer JS. Cell Cycle-dependent Changes in Localization and Phosphorylation of the Plasma Membrane Kv2.1 K+ Channel Impact Endoplasmic Reticulum Membrane Contact Sites in COS-1 Cells. J Biol Chem 2015; 290:29189-201. [PMID: 26442584 DOI: 10.1074/jbc.m115.690198] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Indexed: 12/22/2022] Open
Abstract
The plasma membrane (PM) comprises distinct subcellular domains with diverse functions that need to be dynamically coordinated with intracellular events, one of the most impactful being mitosis. The Kv2.1 voltage-gated potassium channel is conditionally localized to large PM clusters that represent specialized PM:endoplasmic reticulum membrane contact sites (PM:ER MCS), and overexpression of Kv2.1 induces more exuberant PM:ER MCS in neurons and in certain heterologous cell types. Localization of Kv2.1 at these contact sites is dynamically regulated by changes in phosphorylation at one or more sites located on its large cytoplasmic C terminus. Here, we show that Kv2.1 expressed in COS-1 cells undergoes dramatic cell cycle-dependent changes in its PM localization, having diffuse localization in interphase cells, and robust clustering during M phase. The mitosis-specific clusters of Kv2.1 are localized to PM:ER MCS, and M phase clustering of Kv2.1 induces more extensive PM:ER MCS. These cell cycle-dependent changes in Kv2.1 localization and the induction of PM:ER MCS are accompanied by increased mitotic Kv2.1 phosphorylation at several C-terminal phosphorylation sites. Phosphorylation of exogenously expressed Kv2.1 is significantly increased upon metaphase arrest in COS-1 and CHO cells, and in a pancreatic β cell line that express endogenous Kv2.1. The M phase clustering of Kv2.1 at PM:ER MCS in COS-1 cells requires the same C-terminal targeting motif needed for conditional Kv2.1 clustering in neurons. The cell cycle-dependent changes in localization and phosphorylation of Kv2.1 were not accompanied by changes in the electrophysiological properties of Kv2.1 expressed in CHO cells. Together, these results provide novel insights into the cell cycle-dependent changes in PM protein localization and phosphorylation.
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Affiliation(s)
- Melanie M Cobb
- From the Departments of Neurobiology, Physiology, and Behavior
| | | | - Jon T Sack
- Physiology and Membrane Biology, and Anesthesiology and Pain Medicine, University of California Davis School of Medicine, Davis, California 95616
| | - James S Trimmer
- From the Departments of Neurobiology, Physiology, and Behavior, Physiology and Membrane Biology, and
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Radulovic M, Anand P, Korsten MA, Gong B. Targeting Ion Channels: An Important Therapeutic Implication in Gastrointestinal Dysmotility in Patients With Spinal Cord Injury. J Neurogastroenterol Motil 2015; 21:494-502. [PMID: 26424038 PMCID: PMC4622131 DOI: 10.5056/jnm15061] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2015] [Revised: 06/10/2015] [Accepted: 07/06/2015] [Indexed: 01/04/2023] Open
Abstract
Gastrointestinal (GI) dysmotility is a severe, and common complication in patients with spinal cord injury (SCI). Current therapeutic methods using acetylcholine analogs or laxative agents have unwanted side effects, besides often fail to have desired effect. Various ion channels such as ATP-sensitive potassium (KATP) channel, calcium ions (Ca2+)-activated potassium ions (K+) channels, voltage-sensitive Ca2+ channels and chloride ion (Cl−) channels are abundantly expressed in GI tissues, and play an important role in regulating GI motility. The release of neurotransmitters from the enteric nerve terminal, innervating GI interstitial cells of Cajal (ICC), and smooth muscle cells (SMC), causes inactivation of K+ and Cl− channels, increasing Ca2+ influx into cytoplasm, resulting in membrane depolarization and smooth muscle contraction. Thus, agents directly regulating ion channels activity either in ICC or in SMC may affect GI peristalsis and would be potential therapeutic target for the treatment of GI dysmotility with SCI.
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Affiliation(s)
- Miroslav Radulovic
- Department of Medicine Icahn School of Medicine at Mount Sinai, New York, NY, USA.,National Center of Excellence for the Medical Consequences of SCI, James J Peters Veteran Affairs Medical Center, Bronx, NY, USA
| | - Preeti Anand
- Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Mark A Korsten
- Department of Medicine Icahn School of Medicine at Mount Sinai, New York, NY, USA.,National Center of Excellence for the Medical Consequences of SCI, James J Peters Veteran Affairs Medical Center, Bronx, NY, USA
| | - Bing Gong
- Department of Medicine Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
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44
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Burke M, Pabbidi MR, Farley J, Roman RJ. Molecular mechanisms of renal blood flow autoregulation. Curr Vasc Pharmacol 2015; 12:845-58. [PMID: 24066938 PMCID: PMC4416696 DOI: 10.2174/15701611113116660149] [Citation(s) in RCA: 97] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Revised: 12/18/2011] [Accepted: 07/02/2013] [Indexed: 01/10/2023]
Abstract
Diabetes and hypertension are the leading causes of chronic kidney disease and their incidence is increasing at
an alarming rate. Both are associated with impairments in the autoregulation of renal blood flow (RBF) and greater transmission
of fluctuations in arterial pressure to the glomerular capillaries. The ability of the kidney to maintain relatively
constant blood flow, glomerular filtration rate (GFR) and glomerular capillary pressure is mediated by the myogenic response
of afferent arterioles working in concert with tubuloglomerular feedback that adjusts the tone of the afferent arteriole
in response to changes in the delivery of sodium chloride to the macula densa. Despite intensive investigation, the factors
initiating the myogenic response and the signaling pathways involved in the myogenic response and tubuloglomerular
feedback remain uncertain. This review focuses on current thought regarding the molecular mechanisms underlying myogenic
control of renal vascular tone, the interrelationships between the myogenic response and tubuloglomerular feedback,
the evidence that alterations in autoregulation of RBF contributes to hypertension and diabetes-induced nephropathy and
the identification of vascular therapeutic targets for improved renoprotection in hypertensive and diabetic patients.
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Affiliation(s)
| | | | | | - Richard J Roman
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS 39216, USA.
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45
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Leblanc N, Forrest AS, Ayon RJ, Wiwchar M, Angermann JE, Pritchard HAT, Singer CA, Valencik ML, Britton F, Greenwood IA. Molecular and functional significance of Ca(2+)-activated Cl(-) channels in pulmonary arterial smooth muscle. Pulm Circ 2015; 5:244-68. [PMID: 26064450 DOI: 10.1086/680189] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 07/22/2014] [Indexed: 12/31/2022] Open
Abstract
Increased peripheral resistance of small distal pulmonary arteries is a hallmark signature of pulmonary hypertension (PH) and is believed to be the consequence of enhanced vasoconstriction to agonists, thickening of the arterial wall due to remodeling, and increased thrombosis. The elevation in arterial tone in PH is attributable, at least in part, to smooth muscle cells of PH patients being more depolarized and displaying higher intracellular Ca(2+) levels than cells from normal subjects. It is now clear that downregulation of voltage-dependent K(+) channels (e.g., Kv1.5) and increased expression and activity of voltage-dependent (Cav1.2) and voltage-independent (e.g., canonical and vanilloid transient receptor potential [TRPC and TRPV]) Ca(2+) channels play an important role in the functional remodeling of pulmonary arteries in PH. This review focuses on an anion-permeable channel that is now considered a novel excitatory mechanism in the systemic and pulmonary circulations. It is permeable to Cl(-) and is activated by a rise in intracellular Ca(2+) concentration (Ca(2+)-activated Cl(-) channel, or CaCC). The first section outlines the biophysical and pharmacological properties of the channel and ends with a description of the molecular candidate genes postulated to encode for CaCCs, with particular emphasis on the bestrophin and the newly discovered TMEM16 and anoctamin families of genes. The second section provides a review of the various sources of Ca(2+) activating CaCCs, which include stimulation by mobilization from intracellular Ca(2+) stores and Ca(2+) entry through voltage-dependent and voltage-independent Ca(2+) channels. The third and final section summarizes recent findings that suggest a potentially important role for CaCCs and the gene TMEM16A in PH.
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Affiliation(s)
- Normand Leblanc
- Department of Pharmacology, University of Nevada School of Medicine, Reno, Nevada, USA
| | - Abigail S Forrest
- Department of Pharmacology, University of Nevada School of Medicine, Reno, Nevada, USA
| | - Ramon J Ayon
- Department of Medicine, University of Illinois, Chicago, Illinois, USA
| | - Michael Wiwchar
- Department of Pharmacology, University of Nevada School of Medicine, Reno, Nevada, USA
| | - Jeff E Angermann
- School of Community Health Sciences, University of Nevada, Reno, Nevada, USA
| | - Harry A T Pritchard
- Vascular Biology Research Centre, Institute of Cardiovascular and Cell Sciences, St. George's University of London, London, United Kingdom
| | - Cherie A Singer
- Department of Pharmacology, University of Nevada School of Medicine, Reno, Nevada, USA
| | - Maria L Valencik
- Department of Biochemistry and Molecular Biology, University of Nevada School of Medicine, Reno, Nevada, USA
| | - Fiona Britton
- Department of Physiology, School of Medical Sciences, University of New South Wales, Sydney, Australia
| | - Iain A Greenwood
- Vascular Biology Research Centre, Institute of Cardiovascular and Cell Sciences, St. George's University of London, London, United Kingdom
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Yang H, Zhang G, Cui J. BK channels: multiple sensors, one activation gate. Front Physiol 2015; 6:29. [PMID: 25705194 PMCID: PMC4319557 DOI: 10.3389/fphys.2015.00029] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Accepted: 01/19/2015] [Indexed: 01/01/2023] Open
Abstract
Ion transport across cell membranes is essential to cell communication and signaling. Passive ion transport is mediated by ion channels, membrane proteins that create ion conducting pores across cell membrane to allow ion flux down electrochemical gradient. Under physiological conditions, majority of ion channel pores are not constitutively open. Instead, structural region(s) within these pores breaks the continuity of the aqueous ion pathway, thereby serves as activation gate(s) to control ions flow in and out. To achieve spatially and temporally regulated ion flux in cells, many ion channels have evolved sensors to detect various environmental stimuli or the metabolic states of the cell and trigger global conformational changes, thereby dynamically operate the opening and closing of their activation gate. The sensors of ion channels can be broadly categorized as chemical sensors and physical sensors to respond to chemical (such as neural transmitters, nucleotides and ions) and physical (such as voltage, mechanical force and temperature) signals, respectively. With the rapidly growing structural and functional information of different types of ion channels, it is now critical to understand how ion channel sensors dynamically control their gates at molecular and atomic level. The voltage and Ca2+ activated BK channels, a K+ channel with an electrical sensor and multiple chemical sensors, provide a unique model system for us to understand how physical and chemical energy synergistically operate its activation gate.
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Affiliation(s)
- Huanghe Yang
- Ion Channel Research Unit, Duke University Medical Center Durham, NC, USA ; Department of Biochemistry, Duke University Medical Center Durham, NC, USA
| | - Guohui Zhang
- Department of Biomedical Engineering, Washington University in Saint Louis St. Louis, MO, USA
| | - Jianmin Cui
- Department of Biomedical Engineering, Washington University in Saint Louis St. Louis, MO, USA ; Cardiac Bioelectricity and Arrhythmia Center, Washington University in Saint Louis St. Louis, MO, USA ; Center for The Investigation of Membrane Excitability Disorders, Washington University in Saint Louis St. Louis, MO, USA
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Wan XJ, Zhao HC, Zhang P, Huo B, Shen BR, Yan ZQ, Qi YX, Jiang ZL. Involvement of BK channel in differentiation of vascular smooth muscle cells induced by mechanical stretch. Int J Biochem Cell Biol 2015; 59:21-9. [DOI: 10.1016/j.biocel.2014.11.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Revised: 11/13/2014] [Accepted: 11/25/2014] [Indexed: 12/26/2022]
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Chen H, Li S, Wang P, Yan S, Hu L, Pan X, Yang C, Leung GP. Endothelium-dependent and -independent relaxation of rat aorta induced by extract of Schizophyllum commune. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2014; 21:1230-1236. [PMID: 25172784 DOI: 10.1016/j.phymed.2014.06.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2014] [Revised: 05/03/2014] [Accepted: 06/19/2014] [Indexed: 06/03/2023]
Abstract
Schizophyllum commune (SC) is widely consumed by Chinese, especially in southern part of China. The aim of the present study was to assess the extract of SC on vascular tone and the mechanisms involved. Experiments were performed on aorta of 18-week-old male Sprague-Dawley rats. Dried SC was extracted with 50% ethanol, 90% ethanol and deionized water, respectively. The effects of SC on the isometric tension of rat aortic rings were measured. Protein expression for the endothelial nitric oxide synthase (eNOS) was also determined in the primarily cultured rat aortic arterial endothelial cells (RAECs). The results showed that the water extract of SC induced a marked relaxation in aortic rings with or without endothelium. After the pretreatments of N(ω)-nitro-l-arginine methyl ester, indomethacin, RP-cAMP, and methylene blue, the SC-induced relaxation was significantly decreased. In addition, the contraction due to Ca(2+) influx and intracellular Ca(2+) release was also inhibited by SC. Furthermore, expression of the eNOS protein was significantly elevated in RAECs after treatment of SC. In conclusion, the water extract of SC induces an endothelium-dependent and -independent relaxation in rat aorta. The relaxing effect of SC involves the modulation of NO-cGMP-dependent pathways, PGI2-cAMP-depedent pathways, Ca(2+) influx though calcium channels and intracellular Ca(2+) release.
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Affiliation(s)
- Haiyun Chen
- Ethnic Drug Screening & Pharmacology Center, Key Laboratory of Chemistry in Ethnic Medicinal Resources, State Ethnic Affairs Commission & Ministry of Education, Yunnan Minzu University, Kunming 650500, PR China
| | - Sujuan Li
- Ethnic Drug Screening & Pharmacology Center, Key Laboratory of Chemistry in Ethnic Medicinal Resources, State Ethnic Affairs Commission & Ministry of Education, Yunnan Minzu University, Kunming 650500, PR China
| | - Peng Wang
- School of Pharmaceutical Science & Yunnan Key Laboratory of Pharmacology for Natural Products, Kunming Medical University, Kunming 650500, PR China
| | - Saimei Yan
- Ethnic Drug Screening & Pharmacology Center, Key Laboratory of Chemistry in Ethnic Medicinal Resources, State Ethnic Affairs Commission & Ministry of Education, Yunnan Minzu University, Kunming 650500, PR China
| | - Lin Hu
- Ethnic Drug Screening & Pharmacology Center, Key Laboratory of Chemistry in Ethnic Medicinal Resources, State Ethnic Affairs Commission & Ministry of Education, Yunnan Minzu University, Kunming 650500, PR China
| | - Xiaoxia Pan
- Ethnic Drug Screening & Pharmacology Center, Key Laboratory of Chemistry in Ethnic Medicinal Resources, State Ethnic Affairs Commission & Ministry of Education, Yunnan Minzu University, Kunming 650500, PR China
| | - Cui Yang
- Ethnic Drug Screening & Pharmacology Center, Key Laboratory of Chemistry in Ethnic Medicinal Resources, State Ethnic Affairs Commission & Ministry of Education, Yunnan Minzu University, Kunming 650500, PR China; Department of Pharmacology & Pharmacy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, PR China.
| | - George Pakheng Leung
- Department of Pharmacology & Pharmacy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, PR China.
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Lai MH, Wu Y, Gao Z, Anderson ME, Dalziel JE, Meredith AL. BK channels regulate sinoatrial node firing rate and cardiac pacing in vivo. Am J Physiol Heart Circ Physiol 2014; 307:H1327-38. [PMID: 25172903 DOI: 10.1152/ajpheart.00354.2014] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Large-conductance Ca(2+)- and voltage-activated K(+) (BK) channels play prominent roles in shaping muscle and neuronal excitability. In the cardiovascular system, BK channels promote vascular relaxation and protect against ischemic injury. Recently, inhibition of BK channels has been shown to lower heart rate in intact rodents and isolated hearts, suggesting a novel role in heart function. However, the underlying mechanism is unclear. In the present study, we recorded ECGs from mice injected with paxilline (PAX), a membrane-permeable BK channel antagonist, and examined changes in cardiac conduction. ECGs revealed a 19 ± 4% PAX-induced reduction in heart rate in wild-type but not BK channel knockout (Kcnma1(-/-)) mice. The heart rate decrease was associated with slowed cardiac pacing due to elongation of the sinus interval. Action potential firing recorded from isolated sinoatrial node cells (SANCs) was reduced by 55 ± 15% and 28 ± 9% by application of PAX (3 μM) and iberiotoxin (230 nM), respectively. Furthermore, baseline firing rates from Kcnma1(-/-) SANCs were 33% lower than wild-type SANCs. The slowed firing upon BK current inhibition or genetic deletion was due to lengthening of the diastolic depolarization phase of the SANC action potential. Finally, BK channel immunoreactivity and PAX-sensitive currents were identified in SANCs with HCN4 expression and pacemaker current, respectively, and BK channels cloned from SANCs recapitulated similar activation as the PAX-sensitive current. Together, these data localize BK channels to SANCs and demonstrate that loss of BK current decreases SANC automaticity, consistent with slowed sinus pacing after PAX injection in vivo. Furthermore, these findings suggest BK channels are potential therapeutic targets for disorders of heart rate.
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Affiliation(s)
- Michael H Lai
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland; Fischell Department of Bioengineering, University of Maryland, College Park, Maryland
| | - Yuejin Wu
- Department of Internal Medicine and the François M. Abboud Cardiovascular Research Center, University of Iowa, Iowa City, Iowa
| | - Zhan Gao
- Department of Internal Medicine and the François M. Abboud Cardiovascular Research Center, University of Iowa, Iowa City, Iowa
| | - Mark E Anderson
- Department of Internal Medicine and the François M. Abboud Cardiovascular Research Center, University of Iowa, Iowa City, Iowa; Department of Physiology and Molecular Biophysics, University of Iowa, Iowa City, Iowa; and
| | - Julie E Dalziel
- AgResearch, Grasslands Research Centre, Palmerston North, New Zealand
| | - Andrea L Meredith
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland; Fischell Department of Bioengineering, University of Maryland, College Park, Maryland;
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Endothelium-independent vasorelaxant effects of hydroalcoholic extract from Nigella sativa seed in rat aorta: the roles of Ca2+ and K+ channels. BIOMED RESEARCH INTERNATIONAL 2014; 2014:247054. [PMID: 24900958 PMCID: PMC4036417 DOI: 10.1155/2014/247054] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Revised: 04/13/2014] [Accepted: 04/21/2014] [Indexed: 12/20/2022]
Abstract
Objective. The aim of this study was to elucidate the mechanism(s) responsible for the vasorelaxant effect of Nigella sativa (N. sativa). Methods. The activity of different concentrations of N. sativa extract was evaluated on contractile responses of isolated aorta to KCl and phenylephrine (PE). Results. The extract (2–14 mg/mL) induced a concentration dependent relaxation both in endothelium-intact and endothelium-denuded aortic rings precontracted by PE (10−6 M) and KCl (6 × 10−2 M). Extract reduced PE- and KCl-induced contractions in presence of cumulative concentrations of calcium (10−5–10−2 M) significantly. L-NAME and indomethacin had no effect on vasorelaxation effect of extract in PE-induced contraction. Diltiazem and heparin reduced significantly this vasorelaxation at a concentration of 14 mg/mL of extract; however, N. sativa-induced relaxation was not affected by ruthenium red. Tetraethylammonium chloride reduced the extract-induced relaxation in concentrations of 2–6 mg/mL of extract significantly but glibenclamide reduced this relaxative effect in all concentrations of extract. Conclusions. The inhibitory effect of N. sativa seed extract on the contraction induced by PE and KCl was endothelium-independent. This relaxation was mediated mainly through the inhibition of Ca2+ and KATP channels and also intracellular calcium release.
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