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Sample records for neuron-specific sodium channel

  1. Targeting sodium channels in cardiac arrhythmia

    NARCIS (Netherlands)

    Remme, Carol Ann; Wilde, Arthur A. M.

    2014-01-01

    Cardiac voltage-gated sodium channels are responsible for proper electrical conduction in the heart. During acquired pathological conditions and inherited sodium channelopathies, altered sodium channel function causes conduction disturbances and ventricular arrhythmias. Although the clinical,

  2. Visualizing individual sodium channels on the move.

    Science.gov (United States)

    Heinemann, Stefan H

    2012-07-27

    Visualization of voltage-gated sodium channels at work is an important requirement for the understanding of rapid electrical signaling in nerve cells. In this issue of Chemistry & Biology, Ondrus and colleagues have mastered this challenge by chemical synthesis of a fluorescent antagonist and by monitoring single sodium channels in living cells with unprecedented optical resolution. Copyright © 2012 Elsevier Ltd. All rights reserved.

  3. On conduction in a bacterial sodium channel.

    Directory of Open Access Journals (Sweden)

    Simone Furini

    Full Text Available Voltage-gated Na⁺-channels are transmembrane proteins that are responsible for the fast depolarizing phase of the action potential in nerve and muscular cells. Selective permeability of Na⁺ over Ca²⁺ or K⁺ ions is essential for the biological function of Na⁺-channels. After the emergence of the first high-resolution structure of a Na⁺-channel, an anionic coordination site was proposed to confer Na⁺ selectivity through partial dehydration of Na⁺ via its direct interaction with conserved glutamate side chains. By combining molecular dynamics simulations and free-energy calculations, a low-energy permeation pathway for Na⁺ ion translocation through the selectivity filter of the recently determined crystal structure of a prokaryotic sodium channel from Arcobacter butzleri is characterised. The picture that emerges is that of a pore preferentially occupied by two ions, which can switch between different configurations by crossing low free-energy barriers. In contrast to K⁺-channels, the movements of the ions appear to be weakly coupled in Na⁺-channels. When the free-energy maps for Na⁺ and K⁺ ions are compared, a selective site is characterised in the narrowest region of the filter, where a hydrated Na⁺ ion, and not a hydrated K⁺ ion, is energetically stable.

  4. Sodium Channel (Dys)Function and Cardiac Arrhythmias

    NARCIS (Netherlands)

    Remme, Carol Ann; Bezzina, Connie R.

    2010-01-01

    P>Cardiac voltage-gated sodium channels are transmembrane proteins located in the cell membrane of cardiomyocytes. Influx of sodium ions through these ion channels is responsible for the initial fast upstroke of the cardiac action potential. This inward sodium current thus triggers the initiation

  5. Voltage-gated sodium channels: action players with many faces

    NARCIS (Netherlands)

    Koopmann, Tamara T.; Bezzina, Connie R.; Wilde, Arthur A. M.

    2006-01-01

    Voltage-gated sodium channels are responsible for the upstroke of the action potential and thereby play an important role in propagation of the electrical impulse in excitable tissues like muscle, nerve and the heart. Duplication of the sodium channels encoding genes during evolution generated the

  6. Amiloride-Sensitive Sodium Channels and Pulmonary Edema

    Directory of Open Access Journals (Sweden)

    Mike Althaus

    2011-01-01

    Full Text Available The development of pulmonary edema can be considered as a combination of alveolar flooding via increased fluid filtration, impaired alveolar-capillary barrier integrity, and disturbed resolution due to decreased alveolar fluid clearance. An important mechanism regulating alveolar fluid clearance is sodium transport across the alveolar epithelium. Transepithelial sodium transport is largely dependent on the activity of sodium channels in alveolar epithelial cells. This paper describes how sodium channels contribute to alveolar fluid clearance under physiological conditions and how deregulation of sodium channel activity might contribute to the pathogenesis of lung diseases associated with pulmonary edema. Furthermore, sodium channels as putative molecular targets for the treatment of pulmonary edema are discussed.

  7. Sodium Channel Mutations and Pyrethroid Resistance in Aedes aegypti

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    Yuzhe Du

    2016-10-01

    Full Text Available Pyrethroid insecticides are widely used to control insect pests and human disease vectors. Voltage-gated sodium channels are the primary targets of pyrethroid insecticides. Mutations in the sodium channel have been shown to be responsible for pyrethroid resistance, known as knockdown resistance (kdr, in various insects including mosquitoes. In Aedes aegypti mosquitoes, the principal urban vectors of dengue, zika, and yellow fever viruses, multiple single nucleotide polymorphisms in the sodium channel gene have been found in pyrethroid-resistant populations and some of them have been functionally confirmed to be responsible for kdr in an in vitro expression system, Xenopus oocytes. This mini-review aims to provide an update on the identification and functional characterization of pyrethroid resistance-associated sodium channel mutations from Aedes aegypti. The collection of kdr mutations not only helped us develop molecular markers for resistance monitoring, but also provided valuable information for computational molecular modeling of pyrethroid receptor sites on the sodium channel.

  8. Metaflumizone is a novel sodium channel blocker insecticide.

    Science.gov (United States)

    Salgado, V L; Hayashi, J H

    2007-12-15

    Metaflumizone is a novel semicarbazone insecticide, derived chemically from the pyrazoline sodium channel blocker insecticides (SCBIs) discovered at Philips-Duphar in the early 1970s, but with greatly improved mammalian safety. This paper describes studies confirming that the insecticidal action of metaflumizone is due to the state-dependent blockage of sodium channels. Larvae of the moth Spodoptera eridania injected with metaflumizone became paralyzed, concomitant with blockage of all nerve activity. Furthermore, tonic firing of abdominal stretch receptor organs from Spodoptera frugiperda was blocked by metaflumizone applied in the bath, consistent with the block of voltage-dependent sodium channels. Studies on native sodium channels, in primary-cultured neurons isolated from the CNS of the larvae of the moth Manduca sexta and on Para/TipE sodium channels heterologously expressed in Xenopus (African clawed frog) oocytes, confirmed that metaflumizone blocks sodium channels by binding selectively to the slow-inactivated state, which is characteristic of the SCBIs. The results confirm that metaflumizone is a novel sodium channel blocker insecticide.

  9. Simplified numerical simulation of hot channel in sodium cooled reactor

    International Nuclear Information System (INIS)

    Fonseca, F. de A.S. da; Silva Filho, E.

    1988-12-01

    The thermal-hydraulic parameter values that restrict the operation of a liquid sodium cooled reactor are not established by the average conditions of the coolant in the reactor core but by the extreme conditions of the hot channel. The present work was developed to analysis of hot channel of a sodium cooled reactor, adapting to this reactor an existent simplified model for hot channel of pressurized water reactor. The model was applied for a standard sodium reactor and the results are considered satisfatory. (author) [pt

  10. Preliminary Plugging tests in Narrow Sodium Channels by Sodium and Carbon Dioxide reaction

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sun Hee; Wi, Myung-Hwan; Min, Jae Hong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-05-15

    This report is on the investigation of the physical/chemical phenomena that a slow loss of CO{sub 2} inventory into sodium after the sodium-CO{sub 2} boundary failure in PCHEs in realistic operating conditions. The first phenomenon is potential channel plugging inside the narrow PCHE channel. Unlike a conventional shell and- tube type HXs, failures in a PCHE are expected to be small cracks. If the faulted channel is blocked, it may have a positive function for plant safety because the pressure boundary would automatically recover due to this self-plugging. The other one is damage propagation on pressure boundary, which is referred to as potential wastage with combined corrosion/erosion effect. Physical/chemical phenomena that a slow loss of CO{sub 2} inventory into sodium after the sodium-CO{sub 2} boundary failure in printed circuit heat exchangers (PCHEs) were investigated. Our preliminary experimental results of plugging show that sodium flow immediately stopped as CO{sub 2} was injected through the nozzle at 300-400 .deg. C in 3 mm sodium channels, whereas sodium flow stopped about 60 min after CO{sub 2} injection in 5 mm sodium channels.

  11. Physiological regulation of epithelial sodium channel by proteolysis

    DEFF Research Database (Denmark)

    Svenningsen, Per; Friis, Ulla G; Bistrup, Claus

    2011-01-01

    PURPOSE OF REVIEW: Activation of epithelial sodium channel (ENaC) by proteolysis appears to be relevant for day-to-day physiological regulation of channel activity in kidney and other epithelial tissues. Pathophysiogical, proteolytic activation of ENaC in kidney has been demonstrated in proteinuric...

  12. Sodium channels as targets for volatile anesthetics

    Directory of Open Access Journals (Sweden)

    Karl F. Herold

    2012-03-01

    Full Text Available The molecular mechanisms of modern inhaled anesthetics although widely used in clinical settings are still poorly understood. Considerable evidence supports effects on membrane proteins such as ligand- and voltage-gated ion channels of excitable cells. Na+ channels are crucial to action potential initiation and propagation, and represent potential targets for volatile anesthetics. Inhibition of presynaptic Na+ channels leads to reduced neurotransmitter release at the synapse and could therefore contribute to the mechanisms by which volatile anesthetics produce their characteristic effects: amnesia, unconsciousness, and immobility. Early studies on crayfish and squid giant axon showed inhibition of Na+ currents by volatile anesthetics. Subsequent studies using native neuronal preparations and heterologous expression systems with various mammalian Na+ channel isoforms implicated inhibition of presynaptic Na+ channels in anesthetic actions. Volatile anesthetics reduce peak Na+ current and shift the voltage of half-maximal steady-state inactivation towards more negative potentials, thus stabilizing the fast-inactivated state. Furthermore recovery from fast-inactivation is slowed together with an enhanced use-dependent block during pulse train protocols. These effects can reduce neurotransmitter release by depressing presynaptic excitability, depolarization and Ca entry, and ultimately transmitter release. This reduction in transmitter release is more portent for glutamatergic vs. GABAergic terminals. Involvement of Na+ channel inhibition in mediating the immobility caused by volatile anesthetics has been demonstrated in animal studies, in which intrathecal infusion of the Na+ channel blocker tetrodotoxin increases volatile anesthetic potency, whereas infusion of the Na+ channels agonist veratridine reduces anesthetic potency. These studies indicate that inhibition of presynaptic Na+ channels by volatile anesthetics is involved in mediating some of

  13. Slack, Slick, and Sodium-Activated Potassium Channels

    Science.gov (United States)

    Kaczmarek, Leonard K.

    2013-01-01

    The Slack and Slick genes encode potassium channels that are very widely expressed in the central nervous system. These channels are activated by elevations in intracellular sodium, such as those that occur during trains of one or more action potentials, or following activation of nonselective cationic neurotransmitter receptors such as AMPA receptors. This review covers the cellular and molecular properties of Slack and Slick channels and compares them with findings on the properties of sodium-activated potassium currents (termed KNa currents) in native neurons. Human mutations in Slack channels produce extremely severe defects in learning and development, suggesting that KNa channels play a central role in neuronal plasticity and intellectual function. PMID:24319675

  14. Investigation of Plugging of Narrow Sodium Channels by Sodium and Carbon Dioxide Interaction

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sun Hee; Wi, Myung-Hwan; Min, Jae Hong; Kim, Tae-joon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-10-15

    The supercritical CO{sub 2} Brayton cycle system is known to be a promising power conversion system for improving the efficiency and preventing the sodium water reaction (SWR) of the current SFR concept using a Rankine steam cycle. PCHEs are known to have potential for reducing the volume occupied by the sodium-to-CO{sub 2} exchangers as well as the heat exchanger mass relative to traditional shell-and-tube heat exchangers. Here, we report a study on a plugging test by the interaction of sodium and CO{sub 2} to investigate design parameters of sodium channels in the realistic operating conditions. We investigated a plugging test by an interaction of sodium and CO{sub 2} with different cross sectional areas of the sodium channels. It was found that the flow rate of sodium decreased earlier and faster with a narrower cross sectional area compared to a wider one. Our experimental results are expected to be used for determining the sodium channel areas of PCHEs.

  15. Voltage-gated sodium channels in taste bud cells.

    Science.gov (United States)

    Gao, Na; Lu, Min; Echeverri, Fernando; Laita, Bianca; Kalabat, Dalia; Williams, Mark E; Hevezi, Peter; Zlotnik, Albert; Moyer, Bryan D

    2009-03-12

    Taste bud cells transmit information regarding the contents of food from taste receptors embedded in apical microvilli to gustatory nerve fibers innervating basolateral membranes. In particular, taste cells depolarize, activate voltage-gated sodium channels, and fire action potentials in response to tastants. Initial cell depolarization is attributable to sodium influx through TRPM5 in sweet, bitter, and umami cells and an undetermined cation influx through an ion channel in sour cells expressing PKD2L1, a candidate sour taste receptor. The molecular identity of the voltage-gated sodium channels that sense depolarizing signals and subsequently initiate action potentials coding taste information to gustatory nerve fibers is unknown. We describe the molecular and histological expression profiles of cation channels involved in electrical signal transmission from apical to basolateral membrane domains. TRPM5 was positioned immediately beneath tight junctions to receive calcium signals originating from sweet, bitter, and umami receptor activation, while PKD2L1 was positioned at the taste pore. Using mouse taste bud and lingual epithelial cells collected by laser capture microdissection, SCN2A, SCN3A, and SCN9A voltage-gated sodium channel transcripts were expressed in taste tissue. SCN2A, SCN3A, and SCN9A were expressed beneath tight junctions in subsets of taste cells. SCN3A and SCN9A were expressed in TRPM5 cells, while SCN2A was expressed in TRPM5 and PKD2L1 cells. HCN4, a gene previously implicated in sour taste, was expressed in PKD2L1 cells and localized to cell processes beneath the taste pore. SCN2A, SCN3A and SCN9A voltage-gated sodium channels are positioned to sense initial depolarizing signals stemming from taste receptor activation and initiate taste cell action potentials. SCN2A, SCN3A and SCN9A gene products likely account for the tetrodotoxin-sensitive sodium currents in taste receptor cells.

  16. Role of aquaporin and sodium channel in pleural water movement.

    Science.gov (United States)

    Jiang, Jinjun; Hu, Jie; Bai, Chunxue

    2003-12-16

    The role of the ENaC sodium channel and aquaporin-1 (AQP1) water channel on pleural fluid dynamics in mice was investigated. 0.25 ml of hypertonic or isosmolar fluid was infused into the pleural space in anesthetized wildtype and AQP1 null mice. Pleural fluid was sampled at specified times to quantify the osmolality and volume. The sodium channel activator terbutaline increased isosmolar fluid clearance by 90% while the sodium channel inhibitor amiloride decreased it by 15%, but had no effect on osmotically driven water transport. AQP1 deletion significantly decreased osmotic water transport in pleural space by twofold, but it had no effect on isosmolar fluid clearance. Pretreatment with dexamethasone increased pleural osmotic fluid entry by 25%, while intravenous injection of HgCl2 decreased osmotic pleural water movement by 43%. These results provided evidence for a role of a sodium channel in pleural fluid absorption; AQP1 plays a major role in osmotic liquid transport but it does not affect isosmolar fluid clearance.

  17. A sodium-channel mutation causes isolated cardiac conduction disease

    NARCIS (Netherlands)

    Tan, HL; Bink-Boelkens, MTE; Bezzina, CR; Viswanathan, PC; Beaufort-Krol, GCM; van Tintelen, PJ; van den Berg, MP; Wilde, AAM; Balser, [No Value

    2001-01-01

    Cardiac conduction disorders slow the heart rhythm and cause disability in millions of people worldwide. Inherited mutations in SCN5A, the gene encoding the human cardiac sodium (Na+) channel, have been associated with rapid heart rhythms that occur suddenly and are life-threatening(1-3); however, a

  18. A sodium-channel mutation causes isolated cardiac conduction disease

    NARCIS (Netherlands)

    Tan, H. L.; Bink-Boelkens, M. T.; Bezzina, C. R.; Viswanathan, P. C.; Beaufort-Krol, G. C.; van Tintelen, P. J.; van den Berg, M. P.; Wilde, A. A.; Balser, J. R.

    2001-01-01

    Cardiac conduction disorders slow the heart rhythm and cause disability in millions of people worldwide. Inherited mutations in SCN5A, the gene encoding the human cardiac sodium (Na+) channel, have been associated with rapid heart rhythms that occur suddenly and are life-threatening; however, a

  19. Voltage-gated sodium channels as targets for pyrethroid insecticides.

    Science.gov (United States)

    Field, Linda M; Emyr Davies, T G; O'Reilly, Andrias O; Williamson, Martin S; Wallace, B A

    2017-10-01

    The pyrethroid insecticides are a very successful group of compounds that have been used extensively for the control of arthropod pests of agricultural crops and vectors of animal and human disease. Unfortunately, this has led to the development of resistance to the compounds in many species. The mode of action of pyrethroids is known to be via interactions with the voltage-gated sodium channel. Understanding how binding to the channel is affected by amino acid substitutions that give rise to resistance has helped to elucidate the mode of action of the compounds and the molecular basis of their selectivity for insects vs mammals and between insects and other arthropods. Modelling of the channel/pyrethroid interactions, coupled with the ability to express mutant channels in oocytes and study function, has led to knowledge of both how the channels function and potentially how to design novel insecticides with greater species selectivity.

  20. Voltage-gated sodium channels in taste bud cells

    Directory of Open Access Journals (Sweden)

    Williams Mark E

    2009-03-01

    Full Text Available Abstract Background Taste bud cells transmit information regarding the contents of food from taste receptors embedded in apical microvilli to gustatory nerve fibers innervating basolateral membranes. In particular, taste cells depolarize, activate voltage-gated sodium channels, and fire action potentials in response to tastants. Initial cell depolarization is attributable to sodium influx through TRPM5 in sweet, bitter, and umami cells and an undetermined cation influx through an ion channel in sour cells expressing PKD2L1, a candidate sour taste receptor. The molecular identity of the voltage-gated sodium channels that sense depolarizing signals and subsequently initiate action potentials coding taste information to gustatory nerve fibers is unknown. Results We describe the molecular and histological expression profiles of cation channels involved in electrical signal transmission from apical to basolateral membrane domains. TRPM5 was positioned immediately beneath tight junctions to receive calcium signals originating from sweet, bitter, and umami receptor activation, while PKD2L1 was positioned at the taste pore. Using mouse taste bud and lingual epithelial cells collected by laser capture microdissection, SCN2A, SCN3A, and SCN9A voltage-gated sodium channel transcripts were expressed in taste tissue. SCN2A, SCN3A, and SCN9A were expressed beneath tight junctions in subsets of taste cells. SCN3A and SCN9A were expressed in TRPM5 cells, while SCN2A was expressed in TRPM5 and PKD2L1 cells. HCN4, a gene previously implicated in sour taste, was expressed in PKD2L1 cells and localized to cell processes beneath the taste pore. Conclusion SCN2A, SCN3A and SCN9A voltage-gated sodium channels are positioned to sense initial depolarizing signals stemming from taste receptor activation and initiate taste cell action potentials. SCN2A, SCN3A and SCN9A gene products likely account for the tetrodotoxin-sensitive sodium currents in taste receptor cells.

  1. Modulation of epithelial sodium channel in human alveolar epithelial ...

    African Journals Online (AJOL)

    Modulation of epithelial sodium channel in human alveolar epithelial cells by lipoxin A4 through AhR-cAMP-dependent pathway. Bi-Huan Cheng1,2, Li-Wei Pan2, Sheng-Rong Zhang3, Bin-Yu Ying2, Ben-Ji. Wang2, Guo-Liang Lin2 and Shi-Fang Ding1*. 1Department of Critical Care Medicine, Qilu Hospital of Shandong ...

  2. Marine Toxins That Target Voltage-gated Sodium Channels

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    Robert J. French

    2006-04-01

    Full Text Available Abstract: Eukaryotic, voltage-gated sodium (NaV channels are large membrane proteins which underlie generation and propagation of rapid electrical signals in nerve, muscle and heart. Nine different NaV receptor sites, for natural ligands and/or drugs, have been identified, based on functional analyses and site-directed mutagenesis. In the marine ecosystem, numerous toxins have evolved to disrupt NaV channel function, either by inhibition of current flow through the channels, or by modifying the activation and inactivation gating processes by which the channels open and close. These toxins function in their native environment as offensive or defensive weapons in prey capture or deterrence of predators. In composition, they range from organic molecules of varying size and complexity to peptides consisting of ~10-70 amino acids. We review the variety of known NaV-targeted marine toxins, outlining, where known, their sites of interaction with the channel protein and their functional effects. In a number of cases, these natural ligands have the potential applications as drugs in clinical settings, or as models for drug development.

  3. Adaptive evolution of the vertebrate skeletal muscle sodium channel

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    Jian Lu

    2011-01-01

    Full Text Available Tetrodotoxin (TTX is a highly potent neurotoxin that blocks the action potential by selectively binding to voltage-gated sodium channels (Na v. The skeletal muscle Na v (Na v1.4 channels in most pufferfish species and certain North American garter snakes are resistant to TTX, whereas in most mammals they are TTX-sensitive. It still remains unclear as to whether the difference in this sensitivity among the various vertebrate species can be associated with adaptive evolution. In this study, we investigated the adaptive evolution of the vertebrate Na v1.4 channels. By means of the CODEML program of the PAML 4.3 package, the lineages of both garter snakes and pufferfishes were denoted to be under positive selection. The positively selected sites identified in the p-loop regions indicated their involvement in Na v1.4 channel sensitivity to TTX. Most of these sites were located in the intracellular regions of the Na v1.4 channel, thereby implying the possible association of these regions with the regulation of voltage-sensor movement.

  4. Toxins That Affect Voltage-Gated Sodium Channels.

    Science.gov (United States)

    Ji, Yonghua

    2017-10-26

    Voltage-gated sodium channels (VGSCs) are critical in generation and conduction of electrical signals in multiple excitable tissues. Natural toxins, produced by animal, plant, and microorganisms, target VGSCs through diverse strategies developed over millions of years of evolutions. Studying of the diverse interaction between VGSC and VGSC-targeting toxins has been contributing to the increasing understanding of molecular structure and function, pharmacology, and drug development potential of VGSCs. This chapter aims to summarize some of the current views on the VGSC-toxin interaction based on the established receptor sites of VGSC for natural toxins.

  5. Intracellular calcium modulation of voltage-gated sodium channels in ventricular myocytes

    NARCIS (Netherlands)

    Casini, Simona; Verkerk, Arie O.; van Borren, Marcel M. G. J.; van Ginneken, Antoni C. G.; Veldkamp, Marieke W.; de Bakker, Jacques M. T.; Tan, Hanno L.

    2009-01-01

    AIMS: Cardiac voltage-gated sodium channels control action potential (AP) upstroke and cell excitability. Intracellular calcium (Ca(i)(2+)) regulates AP properties by modulating various ion channels. Whether Ca(i)(2+) modulates sodium channels in ventricular myocytes, is unresolved. We studied

  6. Design of a Nested Eight-Channel Sodium and Four-Channel Proton Coil for 7 Tesla Knee Imaging

    Science.gov (United States)

    Brown, Ryan; Madelin, Guillaume; Lattanzi, Riccardo; Chang, Gregory; Regatte, Ravinder R.; Sodickson, Daniel K.; Wiggins, Graham C.

    2012-01-01

    The critical design aim for a dual-tuned sodium/proton coil is to maximize sodium sensitivity and transmit field (B1+) homogeneity while simultaneously providing adequate proton sensitivity and homogeneity. While most dual-frequency coils utilize lossy high-impedance trap circuits or PIN diodes to allow dual-resonance, we explored a nested-coil design for sodium/proton knee imaging at 7T. A stand-alone eight-channel sodium receive array was implemented without standard dual-resonance circuitry to provide improved sodium signal-to-noise ratio (SNR) over a volume coil. A detunable sodium birdcage was added for homogeneous sodium excitation and a four-channel proton transmit-receive array was added to provide anatomical reference imaging and B0 shimming capability. Both modules were implemented with minimal disturbance to the eight-channel sodium array by managing their respective resonances and geometrical arrangement. In vivo sodium SNR was 1.2 to 1.7 times greater in the developed eight-channel array than in a mono-nuclear sodium birdcage coil, while the developed four-channel proton array provided SNR similar to that of a commercial mono-nuclear proton birdcage coil. PMID:22887123

  7. Single sodium channels from human skeletal muscle in planar lipid bilayers: characterization and response to pentobarbital

    NARCIS (Netherlands)

    Wartenberg, Hans C.; Urban, Bernd W.

    2004-01-01

    PURPOSE: To investigate the response to general anesthetics of different sodium-channel subtypes, we examined the effects of pentobarbital, a close thiopental analogue, on single sodium channels from human skeletal muscle and compared them to existing data from human brain and human ventricular

  8. Cation gating and selectivity in a purified, reconstituted, voltage-dependent sodium channel

    International Nuclear Information System (INIS)

    Barchi, R.L.; Tanaka, J.C.

    1984-01-01

    In excitable membranes, the voltage-dependent sodium channel controls the primary membrane conductance change necessary for the generation of an action potential. Over the past four decades, the time- and voltage-dependent sodium currents gated by this channel have been thoroughly documented with increasingly sophisticated voltage-clamp techniques. Recent advances in the biochemistry of membrane proteins have led to the solubilization and purification of this channel protein from nerve (6) and from muscle (4) or muscle-derived (1) membranes, and have provided an approach to the correlation of the channel's molecular structure with its functional properties. Each of these sodium channel preparations appears to contain a large glycoprotein either as its sole component (2) or in association with several small subunits (6, 3). Evidence that these purified proteins represent the excitable membrane sodium channel is presented. 8 refs., 1 fig., 1 tab

  9. Distinct molecular sites of anaesthetic action: pentobarbital block of human brain sodium channels is alleviated by removal of fast inactivation

    NARCIS (Netherlands)

    Wartenberg, H. C.; Urban, B. W.; Duch, D. S.

    1999-01-01

    Fast inactivation of sodium channel function is modified by anaesthetics. Its quantitative contribution to the overall anaesthetic effect is assessed by removing the fast inactivation mechanism enzymatically. Sodium channels from human brain cortex were incorporated into planar lipid bilayers. After

  10. Action of insecticidal N-alkylamides at site 2 of the voltage-sensitive sodium channel

    International Nuclear Information System (INIS)

    Ottea, J.A.; Payne, G.T.; Soderlund, D.M.

    1990-01-01

    Nine synthetic N-alkylamides were examined as inhibitors of the specific binding of [ 3 H]batrachotoxinin A 20α-benzoate ([ 3 H]BTX-B) to sodium channels and as activators of sodium uptake in mouse brain synaptoneurosomes. In the presence of scorpion (Leiurus quinquestriatus) venom, the six insecticidal analogues were active as both inhibitors of [ 3 H]BTX-B binding and stimulators of sodium uptake. These findings are consistent with an action of these compounds at the alkaloid activator recognition site (site 2) of the voltage-sensitive sodium channel. The three noninsecticidal N-alkylamides also inhibited [ 3 H]BTX-B binding but were ineffective as activators of sodium uptake. Concentration-response studies revealed that some of the insecticidal amides also enhanced sodium uptake through a second, high-affinity interaction that does not involve site 2, but this secondary effect does not appear to be correlated with insecticidal activity. The activities of N-alkylamides as sodium channel activators were influenced by the length of the alkenyl chain and the location of unsaturation within the molecule. These results further define the actions of N-alkylamides on sodium channels and illustrate the significance of the multiple binding domains of the sodium channel as target sites for insect control agents

  11. Molecular and kinetic determinants of local anaesthetic action on sodium channels.

    Science.gov (United States)

    French, R J; Zamponi, G W; Sierralta, I E

    1998-11-23

    (1) Local anaesthetics (LA) rely for their clinical actions on state-dependent inhibition of voltage-dependent sodium channels. (2) Single, batrachoxin-modified sodium channels in planar lipid bilayers allow direct observation of drug-channel interactions. Two modes of inhibition of single-channel current are observed: fast block of the open channels and prolongation of a long-lived closed state, some of whose properties resemble those of the inactivated state of unmodified channels. (3) Analogues of different parts of the LA molecule separately mimic each blocking mode: amines--fast block, and water-soluble aromatics--closed state prolongation. (4) Interaction between a mu-conotoxin derivative and diethylammonium indicate an intrapore site of fast, open-state block. (5) Site-directed mutagenesis studies suggest that hydrophobic residues in transmembrane segment 6 of repeat domain 4 of sodium channels are critical for both LA binding and stabilization of the inactivated state.

  12. The Sodium-Activated Potassium Channel Slack Is Required for Optimal Cognitive Flexibility in Mice

    Science.gov (United States)

    Bausch, Anne E.; Dieter, Rebekka; Nann, Yvette; Hausmann, Mario; Meyerdierks, Nora; Kaczmarek, Leonard K.; Ruth, Peter; Lukowski, Robert

    2015-01-01

    "Kcnt1" encoded sodium-activated potassium channels (Slack channels) are highly expressed throughout the brain where they modulate the firing patterns and general excitability of many types of neurons. Increasing evidence suggests that Slack channels may be important for higher brain functions such as cognition and normal intellectual…

  13. Expression, purification and functional reconstitution of slack sodium-activated potassium channels.

    Science.gov (United States)

    Yan, Yangyang; Yang, Youshan; Bian, Shumin; Sigworth, Fred J

    2012-11-01

    The slack (slo2.2) gene codes for a potassium-channel α-subunit of the 6TM voltage-gated channel family. Expression of slack results in Na(+)-activated potassium channel activity in various cell types. We describe the purification and reconstitution of Slack protein and show that the Slack α-subunit alone is sufficient for potassium channel activity activated by sodium ions as assayed in planar bilayer membranes and in membrane vesicles.

  14. Antiepileptic drugs targeting sodium channels: subunit and neuron-type specific interactions

    NARCIS (Netherlands)

    Qiao, X.

    2013-01-01

    Certain antiepileptic drugs (e.g. carbamazepine and lamotrigine) block sodium channels in an use-dependent manner and this mechanism contributes to the anti-convulsant properties of these drugs. There are, however, subtle differences in sodium current blocking properties of the antiepileptic drugs

  15. Identification of sodium channel isoforms that mediate action potential firing in lamina I/II spinal cord neurons

    Directory of Open Access Journals (Sweden)

    Smith Paula L

    2011-09-01

    Full Text Available Abstract Background Voltage-gated sodium channels play key roles in acute and chronic pain processing. The molecular, biophysical, and pharmacological properties of sodium channel currents have been extensively studied for peripheral nociceptors while the properties of sodium channel currents in dorsal horn spinal cord neurons remain incompletely understood. Thus far, investigations into the roles of sodium channel function in nociceptive signaling have primarily focused on recombinant channels or peripheral nociceptors. Here, we utilize recordings from lamina I/II neurons withdrawn from the surface of spinal cord slices to systematically determine the functional properties of sodium channels expressed within the superficial dorsal horn. Results Sodium channel currents within lamina I/II neurons exhibited relatively hyperpolarized voltage-dependent properties and fast kinetics of both inactivation and recovery from inactivation, enabling small changes in neuronal membrane potentials to have large effects on intrinsic excitability. By combining biophysical and pharmacological channel properties with quantitative real-time PCR results, we demonstrate that functional sodium channel currents within lamina I/II neurons are predominantly composed of the NaV1.2 and NaV1.3 isoforms. Conclusions Overall, lamina I/II neurons express a unique combination of functional sodium channels that are highly divergent from the sodium channel isoforms found within peripheral nociceptors, creating potentially complementary or distinct ion channel targets for future pain therapeutics.

  16. Modification of sodium and potassium channel kinetics by diethyl ether and studies on sodium channel inactivation in the crayfish giant axon membrane

    Energy Technology Data Exchange (ETDEWEB)

    Bean, Bruce Palmer [Univ. of Rochester, NY (United States)

    1979-01-01

    The effects of ether and halothane on membrane currents in the voltage clamped crayfish giant axon membrane were investigated. Concentrations of ether up to 300 mM and of halothane up to 32 mM had no effect on resting potential or leakage conductance. Ether and halothane reduced the size of sodium currents without changing the voltage dependence of the peak currents or their reversal potential. Ether and halothane also produced a reversible, dose-dependent speeding of sodium current decay at all membrane potentials. Ether reduced the time constants for inactivation, and also shifted the midpoint of the steady-state inactivation curve in the hyperpolarizing direction. Potassium currents were smaller with ether present, with no change in the voltage dependence of steady-state currents. The activation of potassium channels was faster with ether present. There was no apparent change in the capacitance of the crayfish giant axon membrane with ether concentrations of up to 100 mM. Experiments on sodium channel inactivation kinetics were performed using 4-aminopyridine to block potassium currents. Sodium currents decayed with a time course generally fit well by a single exponential. The time constant of decay was a steep function of voltage, especially in the negative resistance region of the peak current vs voltage relation.The time course of inactivation was very similar to that of the decay of the current at the same potential. The measurement of steady-state inactivation curves with different test pulses showed no shifts along the voltage asix. The voltage-dependence of the integral of sodium conductance was measured to test models of sodium channel inactivation in which channels must open before inactivating; the results appear inconsistent with some of the simplest cases of such models.

  17. Molecular Basis of Paraltyic Neurotoxin Action on Voltage-Sensitive Sodium Channels

    Science.gov (United States)

    1985-10-14

    of 9,700 daltons isolated from the coral Goni2oora gy. (1). The toxin enhances neurally mediated contraction of blood vessels and taenia coli of the...sites on the solium channel and to identify the site of GPT action within the structure of the sodium channel protein. 2. Site of Action of Brvyetoxin

  18. Action potential generation requires a high sodium channel density in the axon initial segment

    NARCIS (Netherlands)

    Kole, Maarten H. P.; Ilschner, Susanne U.; Kampa, Björn M.; Williams, Stephen R.; Ruben, Peter C.; Stuart, Greg J.

    2008-01-01

    The axon initial segment ( AIS) is a specialized region in neurons where action potentials are initiated. It is commonly assumed that this process requires a high density of voltage-gated sodium ( Na(+)) channels. Paradoxically, the results of patch-clamp studies suggest that the Na(+) channel

  19. Distribution and function of voltage-gated sodium channels in the nervous system.

    Science.gov (United States)

    Wang, Jun; Ou, Shao-Wu; Wang, Yun-Jie

    2017-11-02

    Voltage-gated sodium channels (VGSCs) are the basic ion channels for neuronal excitability, which are crucial for the resting potential and the generation and propagation of action potentials in neurons. To date, at least nine distinct sodium channel isoforms have been detected in the nervous system. Recent studies have identified that voltage-gated sodium channels not only play an essential role in the normal electrophysiological activities of neurons but also have a close relationship with neurological diseases. In this study, the latest research findings regarding the structure, type, distribution, and function of VGSCs in the nervous system and their relationship to neurological diseases, such as epilepsy, neuropathic pain, brain tumors, neural trauma, and multiple sclerosis, are reviewed in detail.

  20. Hydration status regulates sodium flux and inflammatory pathways through epithelial sodium channel (ENaC) in the skin.

    Science.gov (United States)

    Xu, Wei; Hong, Seok Jong; Zeitchek, Michael; Cooper, Garry; Jia, Shengxian; Xie, Ping; Qureshi, Hannan A; Zhong, Aimei; Porterfield, Marshall D; Galiano, Robert D; Surmeier, D James; Mustoe, Thomas A

    2015-03-01

    Although it is known that the inflammatory response that results from disruption of epithelial barrier function after injury results in excessive scarring, the upstream signals remain unknown. It has also been observed that epithelial disruption results in reduced hydration status and that the use of occlusive dressings that prevent water loss from wounds decreases scar formation. We hypothesized that hydration status changes sodium homeostasis and induces sodium flux in keratinocytes, which result in activation of pathways responsible for keratinocyte-fibroblast signaling and ultimately lead to activation of fibroblasts. Here, we demonstrate that perturbations in epithelial barrier function lead to increased sodium flux in keratinocytes. We identified that sodium flux in keratinocytes is mediated by epithelial sodium channels (ENaCs) and causes increased secretion of proinflammatory cytokines, which activate fibroblast via the cyclooxygenase 2 (COX-2)/prostaglandin E2 (PGE2) pathway. Similar changes in signal transduction and sodium flux occur by increased sodium concentration, which simulates reduced hydration, in the media in epithelial cultures or human ex vivo skin cultures. Blockade of ENaC, prostaglandin synthesis, or PGE2 receptors all reduce markers of fibroblast activation and collagen synthesis. In addition, employing a validated in vivo excessive scar model in the rabbit ear, we demonstrate that utilization of either an ENaC blocker or a COX-2 inhibitor results in a marked reduction in scarring. Other experiments demonstrate that the activation of COX-2 in response to increased sodium flux is mediated through the PIK3/Akt pathway. Our results indicate that ENaC responds to small changes in sodium concentration with inflammatory mediators and suggest that the ENaC pathway is a potential target for a strategy to prevent fibrosis.

  1. Propylparaben reduces the excitability of hippocampal neurons by blocking sodium channels.

    Science.gov (United States)

    Lara-Valderrábano, Leonardo; Rocha, Luisa; Galván, Emilio J

    2016-12-01

    Propylparaben (PPB) is an antimicrobial preservative widely used in food, cosmetics, and pharmaceutics. Virtual screening methodologies predicted anticonvulsant activity of PPB that was confirmed in vivo. Thus, we explored the effects of PPB on the excitability of hippocampal neurons by using standard patch clamp techniques. Bath perfusion of PPB reduced the fast-inactivating sodium current (I Na ) amplitude, causing a hyperpolarizing shift in the inactivation curve of the I Na, and markedly delayed the sodium channel recovery from the inactivation state. Also, PPB effectively suppressed the riluzole-sensitive, persistent sodium current (I NaP ). PPB perfusion also modified the action potential kinetics, and higher concentrations of PPB suppressed the spike activity. Nevertheless, the modulatory effects of PPB did not occur when PPB was internally applied by whole-cell dialysis. These results indicate that PPB reduces the excitability of CA1 pyramidal neurons by modulating voltage-dependent sodium channels. The mechanistic basis of this effect is a marked delay in the recovery from inactivation state of the voltage-sensitive sodium channels. Our results indicate that similar to local anesthetics and anticonvulsant drugs that act on sodium channels, PPB acts in a use-dependent manner. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Local anesthetics disrupt energetic coupling between the voltage-sensing segments of a sodium channel.

    Science.gov (United States)

    Muroi, Yukiko; Chanda, Baron

    2009-01-01

    Local anesthetics block sodium channels in a state-dependent fashion, binding with higher affinity to open and/or inactivated states. Gating current measurements show that local anesthetics immobilize a fraction of the gating charge, suggesting that the movement of voltage sensors is modified when a local anesthetic binds to the pore of the sodium channel. Here, using voltage clamp fluorescence measurements, we provide a quantitative description of the effect of local anesthetics on the steady-state behavior of the voltage-sensing segments of a sodium channel. Lidocaine and QX-314 shifted the midpoints of the fluorescence-voltage (F-V) curves of S4 domain III in the hyperpolarizing direction by 57 and 65 mV, respectively. A single mutation in the S6 of domain IV (F1579A), a site critical for local anesthetic block, abolished the effect of QX-314 on the voltage sensor of domain III. Both local anesthetics modestly shifted the F-V relationships of S4 domain IV toward hyperpolarized potentials. In contrast, the F-V curve of the S4 domain I was shifted by 11 mV in the depolarizing direction upon QX-314 binding. These antagonistic effects of the local anesthetic indicate that the drug modifies the coupling between the voltage-sensing domains of the sodium channel. Our findings suggest a novel role of local anesthetics in modulating the gating apparatus of the sodium channel.

  3. Potential Roles of Amiloride-Sensitive Sodium Channels in Cancer Development

    Directory of Open Access Journals (Sweden)

    Siguang Xu

    2016-01-01

    Full Text Available The ENaC/degenerin ion channel superfamily includes the amiloride-sensitive epithelial sodium channel (ENaC and acid sensitive ionic channel (ASIC. ENaC is a multimeric ion channel formed by heteromultimeric membrane glycoproteins, which participate in a multitude of biological processes by mediating the transport of sodium (Na+ across epithelial tissues such as the kidney, lungs, bladder, and gut. Aberrant ENaC functions contribute to several human disease states including pseudohypoaldosteronism, Liddle syndrome, cystic fibrosis, and salt-sensitive hypertension. Increasing evidence suggests that ion channels not only regulate ion homeostasis and electric signaling in excitable cells but also play important roles in cancer cell behaviors such as proliferation, apoptosis, invasion, and migration. Indeed, ENaCs/ASICs had been reported to be associated with cancer characteristics. Given their cell surface localization and pharmacology, pharmacological strategies to target ENaC/ASIC family members may be promising cancer therapeutics.

  4. Voltage-Gated Sodium Channels: Evolutionary History and Distinctive Sequence Features.

    Science.gov (United States)

    Kasimova, M A; Granata, D; Carnevale, V

    2016-01-01

    Voltage-gated sodium channels (Nav) are responsible for the rising phase of the action potential. Their role in electrical signal transmission is so relevant that their emergence is believed to be one of the crucial factors enabling development of nervous system. The presence of voltage-gated sodium-selective channels in bacteria (BacNav) has raised questions concerning the evolutionary history of the ones in animals. Here we review some of the milestones in the field of Nav phylogenetic analysis and discuss some of the most important sequence features that distinguish these channels from voltage-gated potassium channels and transient receptor potential channels. Copyright © 2016 Elsevier Inc. All rights reserved.

  5. Plasmin in Nephrotic Urine Activates the Epithelial Sodium Channel

    DEFF Research Database (Denmark)

    Svenningsen, Per; Bistrup, Claus; Friis, Ulla G

    2009-01-01

    stimulated amiloride-sensitive transepithelial sodium transport in M-1 cells and increased amiloride-sensitive whole-cell currents in Xenopus laevis oocytes heterologously expressing ENaC. Activation of ENaC by plasmin involved cleavage and release of an inhibitory peptide from the ENaC gamma subunit...

  6. A negative charge in transmembrane segment 1 of domain II of the cockroach sodium channel is critical for channel gating and action of pyrethroid insecticides

    International Nuclear Information System (INIS)

    Du Yuzhe; Song Weizhong; Groome, James R.; Nomura, Yoshiko; Luo Ningguang; Dong Ke

    2010-01-01

    Voltage-gated sodium channels are the primary target of pyrethroids, an important class of synthetic insecticides. Pyrethroids bind to a distinct receptor site on sodium channels and prolong the open state by inhibiting channel deactivation and inactivation. Recent studies have begun to reveal sodium channel residues important for pyrethroid binding. However, how pyrethroid binding leads to inhibition of sodium channel deactivation and inactivation remains elusive. In this study, we show that a negatively charged aspartic acid residue at position 802 (D802) located in the extracellular end of transmembrane segment 1 of domain II (IIS1) is critical for both the action of pyrethroids and the voltage dependence of channel activation. Charge-reversing or -neutralizing substitutions (K, G, or A) of D802 shifted the voltage dependence of activation in the depolarizing direction and reduced channel sensitivity to deltamethrin, a pyrethroid insecticide. The charge-reversing mutation D802K also accelerated open-state deactivation, which may have counteracted the inhibition of sodium channel deactivation by deltamethrin. In contrast, the D802G substitution slowed open-state deactivation, suggesting an additional mechanism for neutralizing the action of deltamethrin. Importantly, Schild analysis showed that D802 is not involved in pyrethroid binding. Thus, we have identified a sodium channel residue that is critical for regulating the action of pyrethroids on the sodium channel without affecting the receptor site of pyrethroids.

  7. Down-regulation of voltage-dependent sodium channels initiated by sodium influx in developing neurons

    International Nuclear Information System (INIS)

    Dargent, B.; Couraud, F.

    1990-01-01

    To address the issue of whether regulatory feedback exists between the electrical activity of a neuron and ion-channel density, the authors investigated the effect of Na + -channel activators (scorpion α toxin, batrachotoxin, and veratridine) on the density of Na + channels in fetal rat brain neurons in vitro. A partial but rapid (t 1/2 , 15 min) disappearance of surface Na + channels was observed as measured by a decrease in the specific binding of [ 3 H]saxitoxin and 125 I-labeled scorpion β toxin and a decrease in specific 22 Na + uptake. Moreover, the increase in the number of Na + channels that normally occurs during neuronal maturation in vitro was inhibited by chronic channel activator treatment. The induced disappearance of Na + channels was abolished by tetrodotoxin, was found to be dependent on the external Na + concentration, and was prevented when either choline (a nonpermeant ion) or Li + (a permeant ion) was substituted for Na + . Amphotericin B, a Na + ionophore, and monensin were able to mimick the effect of Na + -channel activators, while a KCl depolarization failed to do this. This feedback regulation seems to be a neuronal property since Na + -channel density in cultured astrocytes was not affected by channel activator treatment or by amphotericin B. The present evidence suggests that an increase in intracellular Na + concentration, whether elicited by Na + -channel activators or mediated by a Na + ionophore, can induce a decrease in surface Na + channels and therefore is involved in down-regulation of Na + -channel density in fetal rat brain neurons in vitro

  8. Comparative effects of sodium channel blockers in short term rat whole embryo culture

    International Nuclear Information System (INIS)

    Nilsson, Mats F; Sköld, Anna-Carin; Ericson, Ann-Christin; Annas, Anita; Villar, Rodrigo Palma; Cebers, Gvido; Hellmold, Heike; Gustafson, Anne-Lee; Webster, William S

    2013-01-01

    This study was undertaken to examine the effect on the rat embryonic heart of two experimental drugs (AZA and AZB) which are known to block the sodium channel Nav1.5, the hERG potassium channel and the L-type calcium channel. The sodium channel blockers bupivacaine, lidocaine, and the L-type calcium channel blocker nifedipine were used as reference substances. The experimental model was the gestational day (GD) 13 rat embryo cultured in vitro. In this model the embryonic heart activity can be directly observed, recorded and analyzed using computer assisted image analysis as it responds to the addition of test drugs. The effect on the heart was studied for a range of concentrations and for a duration up to 3 h. The results showed that AZA and AZB caused a concentration-dependent bradycardia of the embryonic heart and at high concentrations heart block. These effects were reversible on washout. In terms of potency to cause bradycardia the compounds were ranked AZB > bupivacaine > AZA > lidocaine > nifedipine. Comparison with results from previous studies with more specific ion channel blockers suggests that the primary effect of AZA and AZB was sodium channel blockage. The study shows that the short-term rat whole embryo culture (WEC) is a suitable system to detect substances hazardous to the embryonic heart. - Highlights: • Study of the effect of sodium channel blocking drugs on embryonic heart function • We used a modified method rat whole embryo culture with image analysis. • The drugs tested caused a concentration dependent bradycardia and heart block. • The effect of drugs acting on multiple ion channels is difficult to predict. • This method may be used to detect cardiotoxicity in prenatal development

  9. Comparative effects of sodium channel blockers in short term rat whole embryo culture

    Energy Technology Data Exchange (ETDEWEB)

    Nilsson, Mats F, E-mail: Mats.Nilsson@farmbio.uu.se [Department of Pharmaceutical Biosciences, Uppsala University (Sweden); Sköld, Anna-Carin; Ericson, Ann-Christin; Annas, Anita; Villar, Rodrigo Palma [AstraZeneca R and D Södertälje (Sweden); Cebers, Gvido [AstraZeneca R and D, iMed, 141 Portland Street, Cambridge, MA 02139 (United States); Hellmold, Heike; Gustafson, Anne-Lee [AstraZeneca R and D Södertälje (Sweden); Webster, William S [Department of Anatomy and Histology, University of Sydney (Australia)

    2013-10-15

    This study was undertaken to examine the effect on the rat embryonic heart of two experimental drugs (AZA and AZB) which are known to block the sodium channel Nav1.5, the hERG potassium channel and the L-type calcium channel. The sodium channel blockers bupivacaine, lidocaine, and the L-type calcium channel blocker nifedipine were used as reference substances. The experimental model was the gestational day (GD) 13 rat embryo cultured in vitro. In this model the embryonic heart activity can be directly observed, recorded and analyzed using computer assisted image analysis as it responds to the addition of test drugs. The effect on the heart was studied for a range of concentrations and for a duration up to 3 h. The results showed that AZA and AZB caused a concentration-dependent bradycardia of the embryonic heart and at high concentrations heart block. These effects were reversible on washout. In terms of potency to cause bradycardia the compounds were ranked AZB > bupivacaine > AZA > lidocaine > nifedipine. Comparison with results from previous studies with more specific ion channel blockers suggests that the primary effect of AZA and AZB was sodium channel blockage. The study shows that the short-term rat whole embryo culture (WEC) is a suitable system to detect substances hazardous to the embryonic heart. - Highlights: • Study of the effect of sodium channel blocking drugs on embryonic heart function • We used a modified method rat whole embryo culture with image analysis. • The drugs tested caused a concentration dependent bradycardia and heart block. • The effect of drugs acting on multiple ion channels is difficult to predict. • This method may be used to detect cardiotoxicity in prenatal development.

  10. β1 subunit stabilises sodium channel Nav1.7 against mechanical stress.

    Science.gov (United States)

    Körner, Jannis; Meents, Jannis; Machtens, Jan-Philipp; Lampert, Angelika

    2018-06-01

    The voltage-gated sodium channel Nav1.7 is a key player in neuronal excitability and pain signalling. In addition to voltage sensing, the channel is also modulated by mechanical stress. Using whole-cell patch-clamp experiments, we discovered that the sodium channel subunit β1 is able to prevent the impact of mechanical stress on Nav1.7. An intramolecular disulfide bond of β1 was identified to be essential for stabilisation of inactivation, but not activation, against mechanical stress using molecular dynamics simulations, homology modelling and site-directed mutagenesis. Our results highlight the role of segment 6 of domain IV in fast inactivation. We present a candidate mechanism for sodium channel stabilisation against mechanical stress, ensuring reliable channel functionality in living systems. Voltage-gated sodium channels are key players in neuronal excitability and pain signalling. Precise gating of these channels is crucial as even small functional alterations can lead to pathological phenotypes such as pain or heart failure. Mechanical stress has been shown to affect sodium channel activation and inactivation. This suggests that stabilising components are necessary to ensure precise channel gating in living organisms. Here, we show that mechanical shear stress affects voltage dependence of activation and fast inactivation of the Nav1.7 channel. Co-expression of the β1 subunit, however, protects both gating modes of Nav1.7 against mechanical shear stress. Using molecular dynamics simulation, homology modelling and site-directed mutagenesis, we identify an intramolecular disulfide bond of β1 (Cys21-Cys43) which is partially involved in this process: the β1-C43A mutant prevents mechanical modulation of voltage dependence of activation, but not of fast inactivation. Our data emphasise the unique role of segment 6 of domain IV for sodium channel fast inactivation and confirm previous reports that the intracellular process of fast inactivation can be

  11. Functionalized Fullerene Targeting Human Voltage-Gated Sodium Channel, hNav1.7.

    Science.gov (United States)

    Hilder, Tamsyn A; Robinson, Anna; Chung, Shin-Ho

    2017-08-16

    Mutations of hNa v 1.7 that cause its activities to be enhanced contribute to severe neuropathic pain. Only a small number of hNa v 1.7 specific inhibitors have been identified, most of which interact with the voltage-sensing domain of the voltage-activated sodium ion channel. In our previous computational study, we demonstrated that a [Lys 6 ]-C 84 fullerene binds tightly (affinity of 46 nM) to Na v Ab, the voltage-gated sodium channel from the bacterium Arcobacter butzleri. Here, we extend this work and, using molecular dynamics simulations, demonstrate that the same [Lys 6 ]-C 84 fullerene binds strongly (2.7 nM) to the pore of a modeled human sodium ion channel hNa v 1.7. In contrast, the fullerene binds only weakly to a mutated model of hNa v 1.7 (I1399D) (14.5 mM) and a model of the skeletal muscle hNa v 1.4 (3.7 mM). Comparison of one representative sequence from each of the nine human sodium channel isoforms shows that only hNa v 1.7 possesses residues that are critical for binding the fullerene derivative and blocking the channel pore.

  12. Sodium channel blockade with QRS widening after an escitalopram overdose.

    Science.gov (United States)

    Schreffler, Susan M; Marraffa, Jeanna M; Stork, Christine M; Mackey, Jennifer

    2013-09-01

    Escitalopram is rarely associated with prolongation of the QTc interval; however, there are no reported cases of QRS complex widening associated with escitalopram overdose. We report a case of a patient who presented with both QRS complex widening and QTc interval prolongation after an escitalopram overdose. A 16-year-old girl presented to the emergency department after ingestion of escitalopram, tramadol/acetaminophen, and hydrocodone/acetaminophen. Laboratory results were significant for 4-hour acetaminophen 21.1 μg/mL. Serum electrolytes including potassium, magnesium, and calcium were all normal. Initial electrocardiogram (ECG) revealed a widened QRS with an incomplete right bundle branch pattern. After administration of 100-mEq sodium bicarbonate, a repeat ECG revealed narrowing of the QRS complex and a prolonged QTc interval. Magnesium sulfate 2 g intravenous and sodium bicarbonate drip were initiated. A repeat ECG, 1 hour after the second, revealed normalization of the QRS complex and QTc interval. Prolongation of the QTc interval is an expected effect of escitalopram. Both escitalopram and citalopram are metabolized to the cardiotoxic metabolite S-didesmethylcitalopram and didesmethylcitalopram, respectively, which have been implicated in numerous cardiac abnormalities including widening of the QRS complex. Although never previously described with escitalopram, this mechanism provides a reasonable explanation for the QRS complex widening and incomplete right bundle branch block that occurred in our patient. Both QRS complex widening and QTc interval prolongation should be monitored in cases of escitalopram and citalopram overdoses.

  13. Mechanism of sodium channel block by local anesthetics, antiarrhythmics, and anticonvulsants.

    Science.gov (United States)

    Tikhonov, Denis B; Zhorov, Boris S

    2017-04-03

    Local anesthetics, antiarrhythmics, and anticonvulsants include both charged and electroneutral compounds that block voltage-gated sodium channels. Prior studies have revealed a common drug-binding region within the pore, but details about the binding sites and mechanism of block remain unclear. Here, we use the x-ray structure of a prokaryotic sodium channel, NavMs, to model a eukaryotic channel and dock representative ligands. These include lidocaine, QX-314, cocaine, quinidine, lamotrigine, carbamazepine (CMZ), phenytoin, lacosamide, sipatrigine, and bisphenol A. Preliminary calculations demonstrated that a sodium ion near the selectivity filter attracts electroneutral CMZ but repels cationic lidocaine. Therefore, we further docked electroneutral and cationic drugs with and without a sodium ion, respectively. In our models, all the drugs interact with a phenylalanine in helix IVS6. Electroneutral drugs trap a sodium ion in the proximity of the selectivity filter, and this same site attracts the charged group of cationic ligands. At this position, even small drugs can block the permeation pathway by an electrostatic or steric mechanism. Our study proposes a common pharmacophore for these diverse drugs. It includes a cationic moiety and an aromatic moiety, which are usually linked by four bonds. © 2017 Tikhonov and Zhorov.

  14. Safety and efficacy of a Nav1.7 selective sodium channel blocker in patients with trigeminal neuralgia

    DEFF Research Database (Denmark)

    Zakrzewska, Joanna M; Palmer, Joanne; Morisset, Valerie

    2017-01-01

    BACKGROUND: Current standard of care for trigeminal neuralgia is treatment with the sodium channel blockers carbamazepine and oxcarbazepine, which although effective are associated with poor tolerability and the need for titration. BIIB074, a Nav1.7-selective, state-dependent sodium-channel blocker...

  15. Molecular basis for class Ib anti-arrhythmic inhibition of cardiac sodium channels

    DEFF Research Database (Denmark)

    Pless, Stephan Alexander; Galpin, Jason D; Frankel, Adam

    2011-01-01

    Cardiac sodium channels are established therapeutic targets for the management of inherited and acquired arrhythmias by class I anti-arrhythmic drugs (AADs). These drugs share a common target receptor bearing two highly conserved aromatic side chains, and are subdivided by the Vaughan-Williams...

  16. Loss-of-Function Sodium Channel Mutations in Infancy A Pattern Unfolds

    NARCIS (Netherlands)

    Chockalingam, Priya; Wilde, Arthur A. M.

    2012-01-01

    The role of channelopathies in the pathogenesis of sudden cardiac death (SCD) in patients with structurally normal hearts is a rapidly evolving story.(1) Many ion channels are involved, including loss-of-function sodium channelopathies of which the phenotypic spectrum ranges from lethal arrhythmias

  17. Epoxyeicosatrienoic acid analogue lowers blood pressure through vasodilation and sodium channel inhibition

    Czech Academy of Sciences Publication Activity Database

    Khan, M. A. H.; Pavlov, T. S.; Christain, S. V.; Neckář, Jan; Staruschenko, A.; Gauthier, K. M.; Capdevila, J. H.; Falck, J. R.; Campbell, W. B.; Imig, J. D.

    2014-01-01

    Roč. 127, č. 7 (2014), s. 463-474 ISSN 0143-5221 Institutional support: RVO:67985823 Keywords : angiotensin II * epithelial sodium channel (ENaC) * epoxyeicosatrienoic acid analogue * hypertension Subject RIV: FA - Cardiovascular Diseases incl. Cardiotharic Surgery Impact factor: 5.598, year: 2014

  18. Distribution and function of sodium channel subtypes in human atrial myocardium

    NARCIS (Netherlands)

    Kaufmann, Susann G.; Westenbroek, Ruth E.; Maass, Alexander H.; Lange, Volkmar; Renner, Andre; Wischmeyer, Erhard; Bonz, Andreas; Muck, Jenny; Ertl, Georg; Catterall, William A.; Scheuer, Todd; Maier, Sebastian K. G.

    Voltage-gated sodium channels composed of a pore-forming alpha subunit and auxiliary beta subunits are responsible for the upstroke of the action potential in cardiac muscle. However, their localization and expression patterns in human myocardium have not yet been clearly defined. We used

  19. Amiloride blocks lithium entry through the sodium channel thereby attenuating the resultant nephrogenic diabetes insipidus.

    NARCIS (Netherlands)

    Kortenoeven, M.L.A.; Li, Y.; Shaw, S.M.; Gaeggeler, H.P.; Rossier, B.C.; Wetzels, J.F.M.; Deen, P.M.T.

    2009-01-01

    Lithium therapy frequently induces nephrogenic diabetes insipidus; amiloride appears to prevent its occurrence in some clinical cases. Amiloride blocks the epithelial sodium channel (ENaC) located in the apical membrane of principal cells; hence one possibility is that ENaC is the main entry site

  20. Modulation of epithelial sodium channel trafficking and function by sodium 4-phenylbutyrate in human nasal epithelial cells.

    Science.gov (United States)

    Prulière-Escabasse, Virginie; Planès, Carole; Escudier, Estelle; Fanen, Pascale; Coste, André; Clerici, Christine

    2007-11-23

    Sodium 4-phenylbutyrate (4-PBA) has been shown to correct the cellular trafficking of several mutant or nonmutant plasma membrane proteins such as cystic fibrosis transmembrane conductance regulator through the expression of 70-kDa heat shock proteins. The objective of the study was to determine whether 4-PBA may influence the functional expression of epithelial sodium channels (ENaC) in human nasal epithelial cells (HNEC). Using primary cultures of HNEC, we demonstrate that 4-PBA (5 mm for 6 h) markedly stimulated amiloride-sensitive sodium channel activity and that this was related to an increased abundance of alpha-, beta-, and gamma-ENaC subunits in the apical membrane. The increase in ENaC cell surface expression (i) was due to insertion of newly ENaC subunits as determined by brefeldin A experiments and (ii) was not associated with cell surface retention of ENaC subunits because endocytosis of ENaC subunits was unchanged. In addition, we find that ENaC co-immunoprecipitated with the heat shock protein constitutively expressed Hsc70, that has been reported to modulate ENaC trafficking, and that 4-PBA decreased Hsc70 protein level. Finally, we report that in cystic fibrosis HNEC obtained from two cystic fibrosis patients, 4-PBA increased functional expression of ENaC as demonstrated by the increase in amiloride-sensitive sodium transport and in alpha-, beta-, and gamma-ENaC subunit expression in the apical membrane. Our results suggest that in HNEC, 4-PBA increases the functional expression of ENaC through the insertion of new alpha-, beta-, and gamma-ENaC subunits into the apical membrane and also suggest that 4-PBA could modify ENaC trafficking by reducing Hsc70 protein expression.

  1. Slick (Kcnt2 Sodium-Activated Potassium Channels Limit Peptidergic Nociceptor Excitability and Hyperalgesia

    Directory of Open Access Journals (Sweden)

    Danielle L Tomasello

    2017-09-01

    Full Text Available The Slick (Kcnt2 sodium-activated potassium (K Na channel is a rapidly gating and weakly voltage-dependent and sodium-dependent potassium channel with no clearly defined physiological function. Within the dorsal root ganglia (DRGs, we show Slick channels are exclusively expressed in small-sized and medium-sized calcitonin gene–related peptide (CGRP-containing DRG neurons, and a pool of channels are localized to large dense-core vesicles (LDCV-containing CGRP. We stimulated DRG neurons for CGRP release and found Slick channels contained within CGRP-positive LDCV translocated to the neuronal membrane. Behavioral studies in Slick knockout (KO mice indicated increased basal heat detection and exacerbated thermal hyperalgesia compared with wild-type littermate controls during neuropathic and chronic inflammatory pain. Electrophysiologic recordings of DRG neurons from Slick KO mice revealed that Slick channels contribute to outward current, propensity to fire action potentials (APs, and to AP properties. Our data suggest that Slick channels restrain the excitability of CGRP-containing neurons, diminishing pain behavior after inflammation and injury.

  2. Asymmetric functional contributions of acidic and aromatic side chains in sodium channel voltage-sensor domains

    DEFF Research Database (Denmark)

    Pless, Stephan Alexander; Elstone, Fisal D; Niciforovic, Ana P

    2014-01-01

    largely enigmatic. To this end, natural and unnatural side chain substitutions were made in the S2 hydrophobic core (HC), the extracellular negative charge cluster (ENC), and the intracellular negative charge cluster (INC) of the four VSDs of the skeletal muscle sodium channel isoform (NaV1......Voltage-gated sodium (NaV) channels mediate electrical excitability in animals. Despite strong sequence conservation among the voltage-sensor domains (VSDs) of closely related voltage-gated potassium (KV) and NaV channels, the functional contributions of individual side chains in Nav VSDs remain.......4). The results show that the highly conserved aromatic side chain constituting the S2 HC makes distinct functional contributions in each of the four NaV domains. No obvious cation-pi interaction exists with nearby S4 charges in any domain, and natural and unnatural mutations at these aromatic sites produce...

  3. Regulation of Epithelial Sodium Transport via Epithelial Na+ Channel

    Science.gov (United States)

    Marunaka, Yoshinori; Niisato, Naomi; Taruno, Akiyuki; Ohta, Mariko; Miyazaki, Hiroaki; Hosogi, Shigekuni; Nakajima, Ken-ichi; Kusuzaki, Katsuyuki; Ashihara, Eishi; Nishio, Kyosuke; Iwasaki, Yoshinobu; Nakahari, Takashi; Kubota, Takahiro

    2011-01-01

    Renal epithelial Na+ transport plays an important role in homeostasis of our body fluid content and blood pressure. Further, the Na+ transport in alveolar epithelial cells essentially controls the amount of alveolar fluid that should be kept at an appropriate level for normal gas exchange. The epithelial Na+ transport is generally mediated through two steps: (1) the entry step of Na+ via epithelial Na+ channel (ENaC) at the apical membrane and (2) the extrusion step of Na+ via the Na+, K+-ATPase at the basolateral membrane. In general, the Na+ entry via ENaC is the rate-limiting step. Therefore, the regulation of ENaC plays an essential role in control of blood pressure and normal gas exchange. In this paper, we discuss two major factors in ENaC regulation: (1) activity of individual ENaC and (2) number of ENaC located at the apical membrane. PMID:22028593

  4. Molecular identity of dendritic voltage-gated sodium channels.

    Science.gov (United States)

    Lorincz, Andrea; Nusser, Zoltan

    2010-05-14

    Active invasion of the dendritic tree by action potentials (APs) generated in the axon is essential for associative synaptic plasticity and neuronal ensemble formation. In cortical pyramidal cells (PCs), this AP back-propagation is supported by dendritic voltage-gated Na+ (Nav) channels, whose molecular identity is unknown. Using a highly sensitive electron microscopic immunogold technique, we revealed the presence of the Nav1.6 subunit in hippocampal CA1 PC proximal and distal dendrites. Here, the subunit density is lower by a factor of 35 to 80 than that found in axon initial segments. A gradual decrease in Nav1.6 density along the proximodistal axis of the dendritic tree was also detected without any labeling in dendritic spines. Our results reveal the characteristic subcellular distribution of the Nav1.6 subunit, identifying this molecule as a key substrate enabling dendritic excitability.

  5. Energetics of discrete selectivity bands and mutation-induced transitions in the calcium-sodium ion channels family.

    Science.gov (United States)

    Kaufman, I; Luchinsky, D G; Tindjong, R; McClintock, P V E; Eisenberg, R S

    2013-11-01

    We use Brownian dynamics (BD) simulations to study the ionic conduction and valence selectivity of a generic electrostatic model of a biological ion channel as functions of the fixed charge Q(f) at its selectivity filter. We are thus able to reconcile the discrete calcium conduction bands recently revealed in our BD simulations, M0 (Q(f)=1e), M1 (3e), M2 (5e), with a set of sodium conduction bands L0 (0.5e), L1 (1.5e), thereby obtaining a completed pattern of conduction and selectivity bands vs Q(f) for the sodium-calcium channels family. An increase of Q(f) leads to an increase of calcium selectivity: L0 (sodium-selective, nonblocking channel) → M0 (nonselective channel) → L1 (sodium-selective channel with divalent block) → M1 (calcium-selective channel exhibiting the anomalous mole fraction effect). We create a consistent identification scheme where the L0 band is putatively identified with the eukaryotic sodium channel The scheme created is able to account for the experimentally observed mutation-induced transformations between nonselective channels, sodium-selective channels, and calcium-selective channels, which we interpret as transitions between different rows of the identification table. By considering the potential energy changes during permeation, we show explicitly that the multi-ion conduction bands of calcium and sodium channels arise as the result of resonant barrierless conduction. The pattern of periodic conduction bands is explained on the basis of sequential neutralization taking account of self-energy, as Q(f)(z,i)=ze(1/2+i), where i is the order of the band and z is the valence of the ion. Our results confirm the crucial influence of electrostatic interactions on conduction and on the Ca(2+)/Na(+) valence selectivity of calcium and sodium ion channels. The model and results could be also applicable to biomimetic nanopores with charged walls.

  6. Structure-based assessment of disease-related mutations in human voltage-gated sodium channels

    Directory of Open Access Journals (Sweden)

    Weiyun Huang

    2017-02-01

    Full Text Available ABSTRACT Voltage-gated sodium (Nav channels are essential for the rapid upstroke of action potentials and the propagation of electrical signals in nerves and muscles. Defects of Nav channels are associated with a variety of channelopathies. More than 1000 disease-related mutations have been identified in Nav channels, with Nav1.1 and Nav1.5 each harboring more than 400 mutations. Nav channels represent major targets for a wide array of neurotoxins and drugs. Atomic structures of Nav channels are required to understand their function and disease mechanisms. The recently determined atomic structure of the rabbit voltage-gated calcium (Cav channel Cav1.1 provides a template for homology-based structural modeling of the evolutionarily related Nav channels. In this Resource article, we summarized all the reported disease-related mutations in human Nav channels, generated a homologous model of human Nav1.7, and structurally mapped disease-associated mutations. Before the determination of structures of human Nav channels, the analysis presented here serves as the base framework for mechanistic investigation of Nav channelopathies and for potential structure-based drug discovery.

  7. Structure-based assessment of disease-related mutations in human voltage-gated sodium channels.

    Science.gov (United States)

    Huang, Weiyun; Liu, Minhao; Yan, S Frank; Yan, Nieng

    2017-06-01

    Voltage-gated sodium (Na v ) channels are essential for the rapid upstroke of action potentials and the propagation of electrical signals in nerves and muscles. Defects of Na v channels are associated with a variety of channelopathies. More than 1000 disease-related mutations have been identified in Na v channels, with Na v 1.1 and Na v 1.5 each harboring more than 400 mutations. Na v channels represent major targets for a wide array of neurotoxins and drugs. Atomic structures of Na v channels are required to understand their function and disease mechanisms. The recently determined atomic structure of the rabbit voltage-gated calcium (Ca v ) channel Ca v 1.1 provides a template for homology-based structural modeling of the evolutionarily related Na v channels. In this Resource article, we summarized all the reported disease-related mutations in human Na v channels, generated a homologous model of human Na v 1.7, and structurally mapped disease-associated mutations. Before the determination of structures of human Na v channels, the analysis presented here serves as the base framework for mechanistic investigation of Na v channelopathies and for potential structure-based drug discovery.

  8. The hitchhiker’s guide to the voltage-gated sodium channel galaxy

    Science.gov (United States)

    2016-01-01

    Eukaryotic voltage-gated sodium (Nav) channels contribute to the rising phase of action potentials and served as an early muse for biophysicists laying the foundation for our current understanding of electrical signaling. Given their central role in electrical excitability, it is not surprising that (a) inherited mutations in genes encoding for Nav channels and their accessory subunits have been linked to excitability disorders in brain, muscle, and heart; and (b) Nav channels are targeted by various drugs and naturally occurring toxins. Although the overall architecture and behavior of these channels are likely to be similar to the more well-studied voltage-gated potassium channels, eukaryotic Nav channels lack structural and functional symmetry, a notable difference that has implications for gating and selectivity. Activation of voltage-sensing modules of the first three domains in Nav channels is sufficient to open the channel pore, whereas movement of the domain IV voltage sensor is correlated with inactivation. Also, structure–function studies of eukaryotic Nav channels show that a set of amino acids in the selectivity filter, referred to as DEKA locus, is essential for Na+ selectivity. Structures of prokaryotic Nav channels have also shed new light on mechanisms of drug block. These structures exhibit lateral fenestrations that are large enough to allow drugs or lipophilic molecules to gain access into the inner vestibule, suggesting that this might be the passage for drug entry into a closed channel. In this Review, we will synthesize our current understanding of Nav channel gating mechanisms, ion selectivity and permeation, and modulation by therapeutics and toxins in light of the new structures of the prokaryotic Nav channels that, for the time being, serve as structural models of their eukaryotic counterparts. PMID:26712848

  9. Mining Protein Evolution for Insights into Mechanisms of Voltage-Dependent Sodium Channel Auxiliary Subunits.

    Science.gov (United States)

    Molinarolo, Steven; Granata, Daniele; Carnevale, Vincenzo; Ahern, Christopher A

    2018-02-21

    Voltage-gated sodium channel (VGSC) beta (β) subunits have been called the "overachieving" auxiliary ion channel subunit. Indeed, these subunits regulate the trafficking of the sodium channel complex at the plasma membrane and simultaneously tune the voltage-dependent properties of the pore-forming alpha-subunit. It is now known that VGSC β-subunits are capable of similar modulation of multiple isoforms of related voltage-gated potassium channels, suggesting that their abilities extend into the broader voltage-gated channels. The gene family for these single transmembrane immunoglobulin beta-fold proteins extends well beyond the traditional VGSC β1-β4 subunit designation, with deep roots into the cell adhesion protein family and myelin-related proteins - where inherited mutations result in a myriad of electrical signaling disorders. Yet, very little is known about how VGSC β-subunits support protein trafficking pathways, the basis for their modulation of voltage-dependent gating, and, ultimately, their role in shaping neuronal excitability. An evolutionary approach can be useful in yielding new clues to such functions as it provides an unbiased assessment of protein residues, folds, and functions. An approach is described here which indicates the greater emergence of the modern β-subunits roughly 400 million years ago in the early neurons of Bilateria and bony fish, and the unexpected presence of distant homologues in bacteriophages. Recent structural breakthroughs containing α and β eukaryotic sodium channels containing subunits suggest a novel role for a highly conserved polar contact that occurs within the transmembrane segments. Overall, a mixture of approaches will ultimately advance our understanding of the mechanism for β-subunit interactions with voltage-sensor containing ion channels and membrane proteins.

  10. Structural inferences for the native skeletal muscle sodium channel as derived from patterns of endogenous proteolysis

    International Nuclear Information System (INIS)

    Kraner, S.; Yang, J.; Barchi, R.

    1989-01-01

    The alpha subunit (Mr approximately 260,000) of the rat skeletal muscle sodium channel is sensitive to cleavage by endogenous proteases during the isolation of muscle surface membrane. Antisera against synthetic oligopeptides were used to map the resultant fragments in order to identify protease-sensitive regions of the channel's structure in its native membrane environment. Antibodies to the amino terminus labeled major fragments of Mr approximately 130,000 and 90,000 and lesser amounts of other peptides as small as Mr approximately 12,000. Antisera to epitopes within the carboxyl-terminal half of the primary sequence recognized two fragments of Mr approximately 110,000 and 78,000. Individual antisera also selectively labeled smaller polypeptides in the most extensively cleaved preparations. The immunoreactivity patterns of monoclonal antibodies previously raised against the purified channel were then surveyed. The binding sites for one group of monoclonals, including several that recognize subtype-specific epitopes in the channel structure, were localized within a 12-kDa fragment near the amino terminus. The distribution of carbohydrate along the primary structure of the channel was also assessed by quantitating 125 I-wheat germ agglutinin and 125I-concanavalin A binding to the proteolytic peptides. Most of the carbohydrate detected by these lectins was located between 22 and 90 kDa from the amino terminus of the protein. No lectin binding was detected to fragments arising from carboxyl-terminal half of the protein. These results were analyzed in terms of current models of sodium channel tertiary structure. In its normal membrane environment, the skeletal muscle sodium channel appears sensitive to cleavage by endogenous proteases in regions predicted to link the four repeat domains on the cytoplasmic side of the membrane while the repeat domains themselves are resistant to proteolysis

  11. Actions of the pyrethroid insecticide bifenthrin on sodium channels expressed in rat cerebral cortical neurons.

    Science.gov (United States)

    Yang, Lin; Li, Li

    2015-01-01

    Voltage-gated sodium channels are important sites for the neurotoxic actions of pyrethroid insecticides in mammals. Here, we studied the mode of action of bifenthrin on the native sodium channels in cerebral cortical neurons prepared from newborn rat brain, where the toxic effects are largely generated. Bifenthrin caused a pronounced late current that persisted at the end of a depolarizing pulse, a slowly-decaying tail current following repolarization and significant resting modification (25.3% modification at 10 μM). No significant bifenthrin-induced effect was observed at the peak current. Bifenthrin also caused a concentration-dependent hyperpolarizing shift in steady-state activation and inactivation as well as slowed recovery from channel inactivation. Repetitive depolarization increased the potency of bifenthrin with high frequency. There was approximately 64% inhibition of modification upon repetitive activation by 10-Hz trains of depolarizing pulses. These results suggest that bifenthrin binds to and modifies sodium channels in both the closed and open states and exhibits the behavior between type I and type II.

  12. Conduction velocity is regulated by sodium channel inactivation in unmyelinated axons innervating the rat cranial meninges.

    Science.gov (United States)

    De Col, Roberto; Messlinger, Karl; Carr, Richard W

    2008-02-15

    Axonal conduction velocity varies according to the level of preceding impulse activity. In unmyelinated axons this typically results in a slowing of conduction velocity and a parallel increase in threshold. It is currently held that Na(+)-K(+)-ATPase-dependent axonal hyperpolarization is responsible for this slowing but this has long been equivocal. We therefore examined conduction velocity changes during repetitive activation of single unmyelinated axons innervating the rat cranial meninges. In direct contradiction to the currently accepted postulate, Na(+)-K(+)-ATPase blockade actually enhanced activity-induced conduction velocity slowing, while the degree of velocity slowing was curtailed in the presence of lidocaine (10-300 microm) and carbamazepine (30-500 microm) but not tetrodotoxin (TTX, 10-80 nm). This suggests that a change in the number of available sodium channels is the most prominent factor responsible for activity-induced changes in conduction velocity in unmyelinated axons. At moderate stimulus frequencies, axonal conduction velocity is determined by an interaction between residual sodium channel inactivation following each impulse and the retrieval of channels from inactivation by a concomitant Na(+)-K(+)-ATPase-mediated hyperpolarization. Since the process is primarily dependent upon sodium channel availability, tracking conduction velocity provides a means of accessing relative changes in the excitability of nociceptive neurons.

  13. Pacemaker rate and depolarization block in nigral dopamine neurons: a somatic sodium channel balancing act

    Science.gov (United States)

    Tucker, Kristal R.; Huertas, Marco A.; Horn, John P.; Canavier, Carmen C.; Levitan, Edwin S.

    2012-01-01

    Midbrain dopamine (DA) neurons are slow intrinsic pacemakers that undergo depolarization (DP) block upon moderate stimulation. Understanding DP block is important because it has been correlated with the clinical efficacy of chronic antipsychotic drug treatment. Here we describe how voltage-gated sodium (NaV) channels regulate DP block and pacemaker activity in DA neurons of the substantia nigra using rat brain slices. The distribution, density and gating of NaV currents were manipulated by blocking native channels with tetrodotoxin and by creating virtual channels and anti-channels with dynamic clamp. Although action potentials initiate in the axon initial segment (AIS) and NaV channels are distributed in multiple dendrites, selective reduction of NaV channel activity in the soma was sufficient to decrease pacemaker frequency and increase susceptibility to DP block. Conversely, increasing somatic NaV current density raised pacemaker frequency and lowered susceptibility to DP block. Finally, when NaV currents were restricted to the soma, pacemaker activity occurred at abnormally high rates due to excessive local subthreshold NaV current. Together with computational simulations, these data show that both the slow pacemaker rate and the sensitivity to DP block that characterizes DA neurons result from the low density of somatic NaV channels. More generally, we conclude that the somatodendritic distribution of NaV channels is a major determinant of repetitive spiking frequency. PMID:23077037

  14. Ligand-based design and synthesis of novel sodium channel blockers from a combined phenytoin–lidocaine pharmacophore

    OpenAIRE

    Wang, Yuesheng; Jones, Paulianda J.; Batts, Timothy W.; Landry, Victoria; Patel, Manoj K.; Brown, Milton L.

    2008-01-01

    The voltage-gated sodium channel remains a rich area for the development of novel blockers. In this study we used comparative molecular field analysis (CoMFA), a ligand-based design strategy, to generate a 3D model based upon local anesthetics, hydantoins, and α-hydroxyphenylamides to elucidate a SAR for their binding site in the neuronal sodium channel. Correlation by partial least squares (PLS) analysis of in vitro sodium channel binding activity (expressed as pIC50) and the CoMFA descripto...

  15. Current-voltage curve of sodium channels and concentration dependence of sodium permeability in frog skin

    DEFF Research Database (Denmark)

    Fuchs, W; Larsen, Erik Hviid; Lindemann, B

    1977-01-01

    1. The inward facing membranes of in vitro frog skin epithelium were depolarized with solutions of high K concentration. The electrical properties of the epithelium are then expected to be governed by the outward facing, Na-selective membrane.2. In this state, the transepithelial voltage (V...... was recorded. This procedure was repeated after blocking the Na channels with amiloride to obtain the current-voltage curve of transmembrane and paracellular shunt pathways. The current-voltage curve of the Na channels was computed by subtracting the shunt current from the total current.4. The instantaneous I...... of the inward facing membranes but reflects the true behaviour of P(Na).6. The steady-state P(Na) at a given (Na)(o) is smaller than the transient P(Na) observed right after a stepwise increase of (Na)(o) to this value. The time constant of P(Na)-relaxation is in the order of seconds.7. In conclusion, Na...

  16. Site of anticonvulsant action on sodium channels: autoradiographic and electrophysiological studies in rat brain

    International Nuclear Information System (INIS)

    Worley, P.F.; Baraban, J.M.

    1987-01-01

    The anticonvulsants phenytoin and carbamazepine interact allosterically with the batrachotoxin binding site of sodium channels. In the present study, we demonstrate an autoradiographic technique to localize the batrachotoxin binding site on sodium channels in rat brain using [ 3 H]batrachotoxinin-A 20-alpha-benzoate (BTX-B). Binding of [ 3 H]BTX-B to brain sections is dependent on potentiating allosteric interactions with scorpion venom and is displaced by BTX-B (Kd approximately 200 nM), aconitine, veratridine, and phenytoin with the same rank order of potencies as described in brain synaptosomes. The maximum number of [ 3 H]BTX-B binding sites in forebrain sections also agrees with biochemical determinations. Autoradiographic localizations indicate that [ 3 H]BTX-B binding sites are not restricted to cell bodies and axons but are present in synaptic zones throughout the brain. For example, a particularly dense concentration of these sites in the substantia nigra is associated with afferent terminals of the striatonigral projection. By contrast, myelinated structures possess much lower densities of binding sites. In addition, we present electrophysiological evidence that synaptic transmission, as opposed to axonal conduction, is preferentially sensitive to the action of aconitine and veratridine. Finally, the synaptic block produced by these sodium channel activators is inhibited by phenytoin and carbamazepine at therapeutic anticonvulsant concentrations

  17. Structure of a eukaryotic voltage-gated sodium channel at near-atomic resolution.

    Science.gov (United States)

    Shen, Huaizong; Zhou, Qiang; Pan, Xiaojing; Li, Zhangqiang; Wu, Jianping; Yan, Nieng

    2017-03-03

    Voltage-gated sodium (Na v ) channels are responsible for the initiation and propagation of action potentials. They are associated with a variety of channelopathies and are targeted by multiple pharmaceutical drugs and natural toxins. Here, we report the cryogenic electron microscopy structure of a putative Na v channel from American cockroach (designated Na v PaS) at 3.8 angstrom resolution. The voltage-sensing domains (VSDs) of the four repeats exhibit distinct conformations. The entrance to the asymmetric selectivity filter vestibule is guarded by heavily glycosylated and disulfide bond-stabilized extracellular loops. On the cytoplasmic side, a conserved amino-terminal domain is placed below VSD I , and a carboxy-terminal domain binds to the III-IV linker. The structure of Na v PaS establishes an important foundation for understanding function and disease mechanism of Na v and related voltage-gated calcium channels. Copyright © 2017, American Association for the Advancement of Science.

  18. Differential distribution of the sodium-activated potassium channels slick and slack in mouse brain.

    Science.gov (United States)

    Rizzi, Sandra; Knaus, Hans-Günther; Schwarzer, Christoph

    2016-07-01

    The sodium-activated potassium channels Slick (Slo2.1, KCNT2) and Slack (Slo2.2, KCNT1) are high-conductance potassium channels of the Slo family. In neurons, Slick and Slack channels are involved in the generation of slow afterhyperpolarization, in the regulation of firing patterns, and in setting and stabilizing the resting membrane potential. The distribution and subcellular localization of Slick and Slack channels in the mouse brain have not yet been established in detail. The present study addresses this issue through in situ hybridization and immunohistochemistry. Both channels were widely distributed and exhibited distinct distribution patterns. However, in some brain regions, their expression overlapped. Intense Slick channel immunoreactivity was observed in processes, varicosities, and neuronal cell bodies of the olfactory bulb, granular zones of cortical regions, hippocampus, amygdala, lateral septal nuclei, certain hypothalamic and midbrain nuclei, and several regions of the brainstem. The Slack channel showed primarily a diffuse immunostaining pattern, and labeling of cell somata and processes was observed only occasionally. The highest Slack channel expression was detected in the olfactory bulb, lateral septal nuclei, basal ganglia, and distinct areas of the midbrain, brainstem, and cerebellar cortex. In addition, comparing our data obtained from mouse brain with a previously published study on rat brain revealed some differences in the expression and distribution of Slick and Slack channels in these species. J. Comp. Neurol. 524:2093-2116, 2016. © 2015 The Authors The Journal of Comparative Neurology Published by Wiley Periodicals, Inc. © 2015 The Authors The Journal of Comparative Neurology Published by Wiley Periodicals, Inc.

  19. To4, the first Tityus obscurus β-toxin fully electrophysiologically characterized on human sodium channel isoforms.

    Science.gov (United States)

    Duque, Harry Morales; Mourão, Caroline Barbosa Farias; Tibery, Diogo Vieira; Barbosa, Eder Alves; Campos, Leandro Ambrósio; Schwartz, Elisabeth Ferroni

    2017-09-01

    Many scorpion toxins that act on sodium channels (NaScTxs) have been characterized till date. These toxins may act modulating the inactivation or the activation of sodium channels and are named α- or β-types, respectively. Some venom toxins from Tityus obscurus (Buthidae), a scorpion widely distributed in the Brazilian Amazon, have been partially characterized in previous studies; however, little information about their electrophysiological role on sodium ion channels has been published. In the present study, we describe the purification, identification and electrophysiological characterization of a NaScTx, which was first described as Tc54 and further fully sequenced and renamed To4. This toxin shows a marked β-type effect on different sodium channel subtypes (hNa v 1.1-hNa v 1.7) at low concentrations, and has more pronounced activity on hNa v 1.1, hNa v 1.2 and hNa v 1.4. By comparing To4 primary structure with other Tityus β-toxins which have already been electrophysiologically tested, it is possible to establish some key amino acid residues for the sodium channel activity. Thus, To4 is the first toxin from T. obscurus fully electrophysiologically characterized on different human sodium channel isoforms. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. Cellular hyper-excitability caused by mutations that alter the activation process of voltage-gated sodium channels

    Directory of Open Access Journals (Sweden)

    Mohamed-Yassine eAMAROUCH

    2015-02-01

    Full Text Available Voltage-gated sodium channels (Nav are widely expressed as macro-molecular complexes in both excitable and non-excitable tissues. In excitable tissues, the upstroke of the action potential is the result of the passage of a large and rapid influx of sodium ions through these channels. NaV dysfunction has been associated with an increasingly wide range of neurological, muscular and cardiac disorders. The purpose of this review is to summarize the recently identified sodium channel mutations that are linked to hyper-excitability phenotypes and associated with the alteration of the activation process of voltage gated sodium channels. Indeed, several clinical manifestations that demonstrate an alteration of tissue excitability were recently shown to be strongly associated with the presence of mutations that affect the activation process of the voltage-gated sodium channels. These emerging genotype-phenotype correlations have expanded the clinical spectrum of sodium channelopathies to include disorders which feature a hyper-excitability phenotype that may or may not be associated with a cardiomyopathy. The p.I141V mutation in SCN4A and SCN5A, as well as its homologous p.I136V mutation in SCN9A, are interesting examples of mutations that have been linked to inherited hyperexcitability myotonia, exercise-induced polymorphic ventricular arrhythmias and erythromelalgia, respectively. Regardless of which sodium channel isoform is investigated, the substitution of the isoleucine to valine in the locus 141 induces similar modifications in the biophysical properties of the voltage-gated sodium channels by shifting the voltage-dependence of steady state activation towards more negative potentials.

  1. Mutations in sodium channel {beta}-subunit SCN3B are associated with early-onset lone atrial fibrillation

    DEFF Research Database (Denmark)

    Olesen, Morten Salling; Jespersen, Thomas; Nielsen, Jonas Bille

    2011-01-01

    AIMS: Atrial fibrillation (AF) is the most frequent arrhythmia. Screening of SCN5A-the gene encoding the a-subunit of the cardiac sodium channel-has indicated that disturbances of the sodium current may play a central role in the mechanism of lone AF. We tested the hypothesis that lone AF in young...... across species. Electrophysiological studies on the SCN3B mutation were carried out and all three SCN3B mutations caused a functionally reduced sodium channel current. One synonymous variant was found in SCN4B. CONCLUSION: In 192 young lone AF patients, we found three patients with suspected disease...

  2. Biological activity of the functional epitope of ciguatoxin fragment AB on the neuroblastoma sodium channel in tissue culture.

    Science.gov (United States)

    Hokama, Y; Chun, K E; Campora, C E; Higa, N; Suma, C; Hamajima, A; Isobe, M

    2006-01-01

    It is well established that the targeted receptor for ciguatoxin (CTX) in mammalian tissues is the sodium channel, affecting the influx of sodium into cells and altering the action potential and function of the cell. Since the syntheses of fragments of CTX has become available, our focus has been on the receptor functions of the west sphere AB and east sphere JKLM fragments using the neuroblastoma cell assay, guinea pig atrium assay, and the membrane immunobead assay (MIA). The data presented here suggest that the west sphere AB of the ciguatoxin molecule is the active portion and is responsible for the activation of the sodium channels. (c) 2006 Wiley-Liss, Inc.

  3. Ionizing radiation alters the properties of sodium channels in rat brain synaptosomes

    Energy Technology Data Exchange (ETDEWEB)

    Mullin, M J; Hunt, W A; Harris, R A

    1986-08-01

    The effect of ionizing radiation on neuronal membrane function was assessed by measurement of neurotoxin-stimulated /sup 22/Na/sup +/ uptake by rat brain synaptosomes. High-energy electrons and gamma photons were equally effective in reducing the maximal uptake of /sup 22/Na/sup +/ with no significant change in the affinity of veratridine for its binding site in the channel. Ionizing radiation reduced the veratridine-stimulated uptake at the earliest times measured (3 and 5 s), when the rate of uptake was greatest. Batrachotoxin-stimulated /sup 22/Na/sup +/ uptake was less sensitive to inhibition by radiation. The binding of (/sup 3/H)saxitoxin to its receptor in the sodium channel was unaffected by exposure to ionizing radiation. The effect of ionizing radiation on the lipid order of rat brain synaptic plasma membranes was measured by the fluorescence polarization of the molecular probes 1,6-diphenyl-1,3,5-hexatriene and 1-(4-(trimethylammonium)phenyl)-6-phenyl-1,3,5-hexatriene. A dose of radiation that reduced the veratridine-stimulated uptake of /sup 22/Na/sup +/ had no effect on the fluorescence polarization of either probe. These results demonstrate an inhibitory effect of ionizing radiation on the voltage-sensitive sodium channels in rat brain synaptosomes. This effect of radiation is not dependent on changes in the order of membrane lipids.

  4. Distribution of cardiac sodium channels in clusters potentiates ephaptic interactions in the intercalated disc.

    Science.gov (United States)

    Hichri, Echrak; Abriel, Hugues; Kucera, Jan P

    2018-02-15

    It has been proposed that ephaptic conduction, relying on interactions between the sodium (Na + ) current and the extracellular potential in intercalated discs, might contribute to cardiac conduction when gap junctional coupling is reduced, but this mechanism is still controversial. In intercalated discs, Na + channels form clusters near gap junction plaques, but the functional significance of these clusters has never been evaluated. In HEK cells expressing cardiac Na + channels, we show that restricting the extracellular space modulates the Na + current, as predicted by corresponding simulations accounting for ephaptic effects. In a high-resolution model of the intercalated disc, clusters of Na + channels that face each other across the intercellular cleft facilitate ephaptic impulse transmission when gap junctional coupling is reduced. Thus, our simulations reveal a functional role for the clustering of Na + channels in intercalated discs, and suggest that rearrangement of these clusters in disease may influence cardiac conduction. It has been proposed that ephaptic interactions in intercalated discs, mediated by extracellular potentials, contribute to cardiac impulse propagation when gap junctional coupling is reduced. However, experiments demonstrating ephaptic effects on the cardiac Na + current (I Na ) are scarce. Furthermore, Na + channels form clusters around gap junction plaques, but the electrophysiological significance of these clusters has never been investigated. In patch clamp experiments with HEK cells stably expressing human Na v 1.5 channels, we examined how restricting the extracellular space modulates I Na elicited by an activation protocol. In parallel, we developed a high-resolution computer model of the intercalated disc to investigate how the distribution of Na + channels influences ephaptic interactions. Approaching the HEK cells to a non-conducting obstacle always increased peak I Na at step potentials near the threshold of I Na activation

  5. Increased renal sodium absorption by inhibition of prostaglandin synthesis during fasting in healthy man. A possible role of the epithelial sodium channels

    Directory of Open Access Journals (Sweden)

    Graffe Carolina C

    2010-10-01

    Full Text Available Abstract Background Treatment with prostaglandin inhibitors can reduce renal function and impair renal water and sodium excretion. We tested the hypotheses that a reduction in prostaglandin synthesis by ibuprofen treatment during fasting decreased renal water and sodium excretion by increased absorption of water and sodium via the aquaporin2 water channels and the epithelial sodium channels. Methods The effect of ibuprofen, 600 mg thrice daily, was measured during fasting in a randomized, placebo-controlled, double-blinded crossover study of 17 healthy humans. The subjects received a standardized diet on day 1, fasted at day 2, and received an IV infusion of 3% NaCl on day 3. The effect variables were urinary excretions of aquaporin2 (u-AQP2, the beta-fraction of the epithelial sodium channel (u-ENaCbeta, cyclic-AMP (u-cAMP, prostaglandin E2 (u-PGE2. Free water clearance (CH2O, fractional excretion of sodium (FENa, and plasma concentrations of vasopressin, angiotensin II, aldosterone, atrial-, and brain natriuretic peptide. Results Ibuprofen decreased u-AQP2, u-PGE2, and FENa at all parts of the study. During the same time, ibuprofen significantly increased u-ENaCbeta. Ibuprofen did not change the response in p-AVP, u-c-AMP, urinary output, and free water clearance during any of these periods. Atrial-and brain natriuretic peptide were higher. Conclusion During inhibition of prostaglandin synthesis, urinary sodium excretion decreased in parallel with an increase in sodium absorption and increase in u-ENaCbeta. U-AQP2 decreased indicating that water transport via AQP2 fell. The vasopressin-c-AMP-axis did not mediate this effect, but it may be a consequence of the changes in the natriuretic peptide system and/or the angiotensin-aldosterone system Trial Registration Clinical Trials Identifier: NCT00281762

  6. The epithelial sodium channel γ-subunit is processed proteolytically in human kidney

    DEFF Research Database (Denmark)

    Langkilde, Rikke Zachar; Skjødt, Karsten; Marcussen, Niels

    2015-01-01

    The epithelial sodium channel (ENaC) of the kidney is necessary for extracellular volume homeostasis and normal arterial BP. Activity of ENaC is enhanced by proteolytic cleavage of the gamma-subunit and putative release of a 43-amino acid inhibitory tract from the gamma-subunit ectodomain. We......ENaC was detected consistently only in tissue from patients with proteinuria and observed in collecting ducts. In conclusion, human kidney gammaENaC is subject to proteolytic cleavage, yielding fragments compatible with furin cleavage, and proteinuria is associated with cleavage at the putative prostasin...

  7. Voltage-gated sodium channels: pharmaceutical targets via anticonvulsants to treat epileptic syndromes.

    Science.gov (United States)

    Abdelsayed, Mena; Sokolov, Stanislav

    2013-01-01

    Epilepsy is a brain disorder characterized by seizures and convulsions. The basis of epilepsy is an increase in neuronal excitability that, in some cases, may be caused by functional defects in neuronal voltage gated sodium channels, Nav1.1 and Nav1.2. The effects of antiepileptic drugs (AEDs) as effective therapies for epilepsy have been characterized by extensive research. Most of the classic AEDs targeting Nav share a common mechanism of action by stabilizing the channel's fast-inactivated state. In contrast, novel AEDs, such as lacosamide, stabilize the slow-inactivated state in neuronal Nav1.1 and Nav1.7 isoforms. This paper reviews the different mechanisms by which this stabilization occurs to determine new methods for treatment.

  8. Hypocretin neuron-specific transcriptome profiling identifies the sleep modulator Kcnh4a.

    Science.gov (United States)

    Yelin-Bekerman, Laura; Elbaz, Idan; Diber, Alex; Dahary, Dvir; Gibbs-Bar, Liron; Alon, Shahar; Lerer-Goldshtein, Tali; Appelbaum, Lior

    2015-10-01

    Sleep has been conserved throughout evolution; however, the molecular and neuronal mechanisms of sleep are largely unknown. The hypothalamic hypocretin/orexin (Hcrt) neurons regulate sleep\\wake states, feeding, stress, and reward. To elucidate the mechanism that enables these various functions and to identify sleep regulators, we combined fluorescence cell sorting and RNA-seq in hcrt:EGFP zebrafish. Dozens of Hcrt-neuron-specific transcripts were identified and comprehensive high-resolution imaging revealed gene-specific localization in all or subsets of Hcrt neurons. Clusters of Hcrt-neuron-specific genes are predicted to be regulated by shared transcription factors. These findings show that Hcrt neurons are heterogeneous and that integrative molecular mechanisms orchestrate their diverse functions. The voltage-gated potassium channel Kcnh4a, which is expressed in all Hcrt neurons, was silenced by the CRISPR-mediated gene inactivation system. The mutant kcnh4a (kcnh4a(-/-)) larvae showed reduced sleep time and consolidation, specifically during the night, suggesting that Kcnh4a regulates sleep.

  9. RING finger protein 121 facilitates the degradation and membrane localization of voltage-gated sodium channels

    Science.gov (United States)

    Ogino, Kazutoyo; Low, Sean E.; Yamada, Kenta; Saint-Amant, Louis; Zhou, Weibin; Muto, Akira; Asakawa, Kazuhide; Nakai, Junichi; Kawakami, Koichi; Kuwada, John Y.; Hirata, Hiromi

    2015-01-01

    Following their synthesis in the endoplasmic reticulum (ER), voltage-gated sodium channels (NaV) are transported to the membranes of excitable cells, where they often cluster, such as at the axon initial segment of neurons. Although the mechanisms by which NaV channels form and maintain clusters have been extensively examined, the processes that govern their transport and degradation have received less attention. Our entry into the study of these processes began with the isolation of a new allele of the zebrafish mutant alligator, which we found to be caused by mutations in the gene encoding really interesting new gene (RING) finger protein 121 (RNF121), an E3-ubiquitin ligase present in the ER and cis-Golgi compartments. Here we demonstrate that RNF121 facilitates two opposing fates of NaV channels: (i) ubiquitin-mediated proteasome degradation and (ii) membrane localization when coexpressed with auxiliary NaVβ subunits. Collectively, these results indicate that RNF121 participates in the quality control of NaV channels during their synthesis and subsequent transport to the membrane. PMID:25691753

  10. Lysine and the Na+/K+ Selectivity in Mammalian Voltage-Gated Sodium Channels.

    Science.gov (United States)

    Li, Yang; Liu, Huihui; Xia, Mengdie; Gong, Haipeng

    2016-01-01

    Voltage-gated sodium (Nav) channels are critical in the generation and transmission of neuronal signals in mammals. The crystal structures of several prokaryotic Nav channels determined in recent years inspire the mechanistic studies on their selection upon the permeable cations (especially between Na+ and K+ ions), a property that is proposed to be mainly determined by residues in the selectivity filter. However, the mechanism of cation selection in mammalian Nav channels lacks direct explanation at atomic level due to the difference in amino acid sequences between mammalian and prokaryotic Nav homologues, especially at the constriction site where the DEKA motif has been identified to determine the Na+/K+ selectivity in mammalian Nav channels but is completely absent in the prokaryotic counterparts. Among the DEKA residues, Lys is of the most importance since its mutation to Arg abolishes the Na+/K+ selectivity. In this work, we modeled the pore domain of mammalian Nav channels by mutating the four residues at the constriction site of a prokaryotic Nav channel (NavRh) to DEKA, and then mechanistically investigated the contribution of Lys in cation selection using molecular dynamics simulations. The DERA mutant was generated as a comparison to understand the loss of ion selectivity caused by the K-to-R mutation. Simulations and free energy calculations on the mutants indicate that Lys facilitates Na+/K+ selection by electrostatically repelling the cation to a highly Na+-selective location sandwiched by the carboxylate groups of Asp and Glu at the constriction site. In contrast, the electrostatic repulsion is substantially weakened when Lys is mutated to Arg, because of two intrinsic properties of the Arg side chain: the planar geometric design and the sparse charge distribution of the guanidine group.

  11. Lysine and the Na+/K+ Selectivity in Mammalian Voltage-Gated Sodium Channels.

    Directory of Open Access Journals (Sweden)

    Yang Li

    Full Text Available Voltage-gated sodium (Nav channels are critical in the generation and transmission of neuronal signals in mammals. The crystal structures of several prokaryotic Nav channels determined in recent years inspire the mechanistic studies on their selection upon the permeable cations (especially between Na+ and K+ ions, a property that is proposed to be mainly determined by residues in the selectivity filter. However, the mechanism of cation selection in mammalian Nav channels lacks direct explanation at atomic level due to the difference in amino acid sequences between mammalian and prokaryotic Nav homologues, especially at the constriction site where the DEKA motif has been identified to determine the Na+/K+ selectivity in mammalian Nav channels but is completely absent in the prokaryotic counterparts. Among the DEKA residues, Lys is of the most importance since its mutation to Arg abolishes the Na+/K+ selectivity. In this work, we modeled the pore domain of mammalian Nav channels by mutating the four residues at the constriction site of a prokaryotic Nav channel (NavRh to DEKA, and then mechanistically investigated the contribution of Lys in cation selection using molecular dynamics simulations. The DERA mutant was generated as a comparison to understand the loss of ion selectivity caused by the K-to-R mutation. Simulations and free energy calculations on the mutants indicate that Lys facilitates Na+/K+ selection by electrostatically repelling the cation to a highly Na+-selective location sandwiched by the carboxylate groups of Asp and Glu at the constriction site. In contrast, the electrostatic repulsion is substantially weakened when Lys is mutated to Arg, because of two intrinsic properties of the Arg side chain: the planar geometric design and the sparse charge distribution of the guanidine group.

  12. Loss of Sodium-Activated Potassium Channel Slack and FMRP Differentially Affect Social Behavior in Mice.

    Science.gov (United States)

    Bausch, Anne E; Ehinger, Rebekka; Straubinger, Julia; Zerfass, Patrick; Nann, Yvette; Lukowski, Robert

    2018-05-31

    The sodium-activated potassium channel Slack (Slo2.2) is widely expressed in central and peripheral neurons where it is supposed to shape firing properties important for neuronal excitability. Slack activity is enhanced by interaction with the Fragile-X-Mental-Retardation-Protein (FMRP) and loss of FMRP leads to decreased sodium-activated potassium currents in medial nucleus of the trapezoid body neurons of the Fmr1-knockout (KO) mouse representing a mouse model of the human Fragile-X-Syndrome (FXS) and autism. Autism is a frequent comorbidity of FXS, but it is unclear whether Slack is involved in autistic or related conditions of FXS in vivo. By applying a wide range of behavioral tests, we compared social and autism-related behaviors in Slack- and FMRP-deficient mice. In our hands, as expected, FMRP-deficiency causes autism-related behavioral changes in nesting and in a marble-burying test. In contrast, Slack-deficient males exhibited specific abnormalities in sociability in direct and indirect social interaction tests. Hence, we show for the first time that a proper Slack channel function is mandatory for normal social behavior in mice. Nevertheless, as deficits in social behaviors seem to occur independently from each other in FMRP and Slack null mutants, we conclude that Slack is not involved in the autistic phenotype of FMRP KO mice. Copyright © 2018 IBRO. Published by Elsevier Ltd. All rights reserved.

  13. Voltage-Gated Sodium Channel β1/β1B Subunits Regulate Cardiac Physiology and Pathophysiology

    Directory of Open Access Journals (Sweden)

    Nnamdi Edokobi

    2018-04-01

    Full Text Available Cardiac myocyte contraction is initiated by a set of intricately orchestrated electrical impulses, collectively known as action potentials (APs. Voltage-gated sodium channels (NaVs are responsible for the upstroke and propagation of APs in excitable cells, including cardiomyocytes. NaVs consist of a single, pore-forming α subunit and two different β subunits. The β subunits are multifunctional cell adhesion molecules and channel modulators that have cell type and subcellular domain specific functional effects. Variants in SCN1B, the gene encoding the Nav-β1 and -β1B subunits, are linked to atrial and ventricular arrhythmias, e.g., Brugada syndrome, as well as to the early infantile epileptic encephalopathy Dravet syndrome, all of which put patients at risk for sudden death. Evidence over the past two decades has demonstrated that Nav-β1/β1B subunits play critical roles in cardiac myocyte physiology, in which they regulate tetrodotoxin-resistant and -sensitive sodium currents, potassium currents, and calcium handling, and that Nav-β1/β1B subunit dysfunction generates substrates for arrhythmias. This review will highlight the role of Nav-β1/β1B subunits in cardiac physiology and pathophysiology.

  14. Sodium

    Science.gov (United States)

    Table salt is a combination of two minerals - sodium and chloride Your body needs some sodium to work properly. It helps with the function ... in your body. Your kidneys control how much sodium is in your body. If you have too ...

  15. A novel tarantula toxin stabilizes the deactivated voltage sensor of bacterial sodium channel.

    Science.gov (United States)

    Tang, Cheng; Zhou, Xi; Nguyen, Phuong Tran; Zhang, Yunxiao; Hu, Zhaotun; Zhang, Changxin; Yarov-Yarovoy, Vladimir; DeCaen, Paul G; Liang, Songping; Liu, Zhonghua

    2017-07-01

    Voltage-gated sodium channels (Na V s) are activated by transiting the voltage sensor from the deactivated to the activated state. The crystal structures of several bacterial Na V s have captured the voltage sensor module (VSM) in an activated state, but structure of the deactivated voltage sensor remains elusive. In this study, we sought to identify peptide toxins stabilizing the deactivated VSM of bacterial Na V s. We screened fractions from several venoms and characterized a cystine knot toxin called JZTx-27 from the venom of tarantula Chilobrachys jingzhao as a high-affinity antagonist of the prokaryotic Na V s Ns V Ba (nonselective voltage-gated Bacillus alcalophilus ) and NaChBac (bacterial sodium channel from Bacillus halodurans ) (IC 50 = 112 nM and 30 nM, respectively). JZTx-27 was more efficacious at weaker depolarizing voltages and significantly slowed the activation but accelerated the deactivation of Ns V Ba, whereas the local anesthetic drug lidocaine was shown to antagonize Ns V Ba without affecting channel gating. Mutation analysis confirmed that JZTx-27 bound to S3-4 linker of Ns V Ba, with F98 being the critical residue in determining toxin affinity. All electrophysiological data and in silico analysis suggested that JZTx-27 trapped VSM of Ns V Ba in one of the deactivated states. In mammalian Na V s, JZTx-27 preferably inhibited the inactivation of Na V 1.5 by targeting the fourth transmembrane domain. To our knowledge, this is the first report of peptide antagonist for prokaryotic Na V s. More important, we proposed that JZTx-27 stabilized the Ns V Ba VSM in the deactivated state and may be used as a probe to determine the structure of the deactivated VSM of Na V s.-Tang, C., Zhou, X., Nguyen, P. T., Zhang, Y., Hu, Z., Zhang, C., Yarov-Yarovoy, V., DeCaen, P. G., Liang, S., Liu, Z. A novel tarantula toxin stabilizes the deactivated voltage sensor of bacterial sodium channel. © FASEB.

  16. Sodium channel Nav1.7 immunoreactivity in painful human dental pulp and burning mouth syndrome

    Directory of Open Access Journals (Sweden)

    Yiangou Yiangos

    2010-06-01

    Full Text Available Abstract Background Voltage gated sodium channels Nav1.7 are involved in nociceptor nerve action potentials and are known to affect pain sensitivity in clinical genetic disorders. Aims and Objectives To study Nav1.7 levels in dental pulpitis pain, an inflammatory condition, and burning mouth syndrome (BMS, considered a neuropathic orofacial pain disorder. Methods Two groups of patients were recruited for this study. One group consisted of patients with dental pulpitis pain (n = 5 and controls (n = 12, and the other patients with BMS (n = 7 and controls (n = 10. BMS patients were diagnosed according to the International Association for the Study of Pain criteria; a pain history was collected, including the visual analogue scale (VAS. Immunohistochemistry with visual intensity and computer image analysis were used to evaluate levels of Nav1.7 in dental pulp tissue samples from the dental pulpitis group, and tongue biopsies from the BMS group. Results There was a significantly increased visual intensity score for Nav1.7 in nerve fibres in the painful dental pulp specimens, compared to controls. Image analysis showed a trend for an increase of the Nav1.7 immunoreactive % area in the painful pulp group, but this was not statistically significant. When expressed as a ratio of the neurofilament % area, there was a strong trend for an increase of Nav1.7 in the painful pulp group. Nav1.7 immunoreactive fibres were seen in abundance in the sub-mucosal layer of tongue biopsies, with no significant difference between BMS and controls. Conclusion Nav1.7 sodium channel may play a significant role in inflammatory dental pain. Clinical trials with selective Nav1.7 channel blockers should prioritise dental pulp pain rather than BMS.

  17. Sodium channel Nav1.7 immunoreactivity in painful human dental pulp and burning mouth syndrome

    Science.gov (United States)

    2010-01-01

    Background Voltage gated sodium channels Nav1.7 are involved in nociceptor nerve action potentials and are known to affect pain sensitivity in clinical genetic disorders. Aims and Objectives To study Nav1.7 levels in dental pulpitis pain, an inflammatory condition, and burning mouth syndrome (BMS), considered a neuropathic orofacial pain disorder. Methods Two groups of patients were recruited for this study. One group consisted of patients with dental pulpitis pain (n = 5) and controls (n = 12), and the other patients with BMS (n = 7) and controls (n = 10). BMS patients were diagnosed according to the International Association for the Study of Pain criteria; a pain history was collected, including the visual analogue scale (VAS). Immunohistochemistry with visual intensity and computer image analysis were used to evaluate levels of Nav1.7 in dental pulp tissue samples from the dental pulpitis group, and tongue biopsies from the BMS group. Results There was a significantly increased visual intensity score for Nav1.7 in nerve fibres in the painful dental pulp specimens, compared to controls. Image analysis showed a trend for an increase of the Nav1.7 immunoreactive % area in the painful pulp group, but this was not statistically significant. When expressed as a ratio of the neurofilament % area, there was a strong trend for an increase of Nav1.7 in the painful pulp group. Nav1.7 immunoreactive fibres were seen in abundance in the sub-mucosal layer of tongue biopsies, with no significant difference between BMS and controls. Conclusion Nav1.7 sodium channel may play a significant role in inflammatory dental pain. Clinical trials with selective Nav1.7 channel blockers should prioritise dental pulp pain rather than BMS. PMID:20529324

  18. A remarkably stable TipE gene cluster: evolution of insect Para sodium channel auxiliary subunits

    Directory of Open Access Journals (Sweden)

    Li Jia

    2011-11-01

    Full Text Available Abstract Background First identified in fruit flies with temperature-sensitive paralysis phenotypes, the Drosophila melanogaster TipE locus encodes four voltage-gated sodium (NaV channel auxiliary subunits. This cluster of TipE-like genes on chromosome 3L, and a fifth family member on chromosome 3R, are important for the optional expression and functionality of the Para NaV channel but appear quite distinct from auxiliary subunits in vertebrates. Here, we exploited available arthropod genomic resources to trace the origin of TipE-like genes by mapping their evolutionary histories and examining their genomic architectures. Results We identified a remarkably conserved synteny block of TipE-like orthologues with well-maintained local gene arrangements from 21 insect species. Homologues in the water flea, Daphnia pulex, suggest an ancestral pancrustacean repertoire of four TipE-like genes; a subsequent gene duplication may have generated functional redundancy allowing gene losses in the silk moth and mosquitoes. Intronic nesting of the insect TipE gene cluster probably occurred following the divergence from crustaceans, but in the flour beetle and silk moth genomes the clusters apparently escaped from nesting. Across Pancrustacea, TipE gene family members have experienced intronic nesting, escape from nesting, retrotransposition, translocation, and gene loss events while generally maintaining their local gene neighbourhoods. D. melanogaster TipE-like genes exhibit coordinated spatial and temporal regulation of expression distinct from their host gene but well-correlated with their regulatory target, the Para NaV channel, suggesting that functional constraints may preserve the TipE gene cluster. We identified homology between TipE-like NaV channel regulators and vertebrate Slo-beta auxiliary subunits of big-conductance calcium-activated potassium (BKCa channels, which suggests that ion channel regulatory partners have evolved distinct lineage

  19. Trafficking regulates the subcellular distribution of voltage-gated sodium channels in primary sensory neurons.

    Science.gov (United States)

    Bao, Lan

    2015-09-30

    Voltage-gated sodium channels (Navs) comprise at least nine pore-forming α subunits. Of these, Nav1.6, Nav1.7, Nav1.8 and Nav1.9 are the most frequently studied in primary sensory neurons located in the dorsal root ganglion and are mainly localized to the cytoplasm. A large pool of intracellular Navs raises the possibility that changes in Nav trafficking could alter channel function. The molecular mediators of Nav trafficking mainly consist of signals within the Navs themselves, interacting proteins and extracellular factors. The surface expression of Navs is achieved by escape from the endoplasmic reticulum and proteasome degradation, forward trafficking and plasma membrane anchoring, and it is also regulated by channel phosphorylation and ubiquitination in primary sensory neurons. Axonal transport and localization of Navs in afferent fibers involves the motor protein KIF5B and scaffold proteins, including contactin and PDZ domain containing 2. Localization of Nav1.6 to the nodes of Ranvier in myelinated fibers of primary sensory neurons requires node formation and the submembrane cytoskeletal protein complex. These findings inform our understanding of the molecular and cellular mechanisms underlying Nav trafficking in primary sensory neurons.

  20. Binding modes and functional surface of anti-mammalian scorpion α-toxins to sodium channels.

    Science.gov (United States)

    Chen, Rong; Chung, Shin-Ho

    2012-10-02

    Scorpion α-toxins bind to the voltage-sensing domains of voltage-gated sodium (Na(V)) channels and interfere with the inactivation mechanisms. The functional surface of α-toxins has been shown to contain an NC-domain consisting of the five-residue turn (positions 8-12) and the C-terminus (positions 56-64) and a core-domain centered on the residue 18. The NC- and core-domains are interconnected by the linker-domain (positions 8-18). Here with atomistic molecular dynamics simulations, we examine the binding modes between two α-toxins, the anti-mammalian AahII and the anti-insect LqhαIT, and the voltage-sensing domain of rat Na(V)1.2, a subtype of Na(V) channels expressed in nerve cells. Both toxins are docked to the extracellular side of the voltage-sensing domain of Na(V)1.2 using molecular dynamics simulations, with the linker-domain assumed to wedge into the binding pocket. Several salt bridges and hydrophobic clusters are observed to form between the NC- and core-domains of the toxins and Na(V)1.2 and stabilize the toxin-channel complexes. The binding modes predicted are consistent with available mutagenesis data and can readily explain the relative affinities of AahII and LqhαIT for Na(V)1.2. The dissociation constants for the two toxin-channel complexes are derived, which compare favorably with experiment. Our models demonstrate that the functional surface of anti-mammalian scorpion α-toxins is centered on the linker-domain, similar to that of β-toxins.

  1. Guanidinium Toxins and Their Interactions with Voltage-Gated Sodium Ion Channels

    Directory of Open Access Journals (Sweden)

    Lorena M. Durán-Riveroll

    2017-10-01

    Full Text Available Guanidinium toxins, such as saxitoxin (STX, tetrodotoxin (TTX and their analogs, are naturally occurring alkaloids with divergent evolutionary origins and biogeographical distribution, but which share the common chemical feature of guanidinium moieties. These guanidinium groups confer high biological activity with high affinity and ion flux blockage capacity for voltage-gated sodium channels (NaV. Members of the STX group, known collectively as paralytic shellfish toxins (PSTs, are produced among three genera of marine dinoflagellates and about a dozen genera of primarily freshwater or brackish water cyanobacteria. In contrast, toxins of the TTX group occur mainly in macrozoa, particularly among puffer fish, several species of marine invertebrates and a few terrestrial amphibians. In the case of TTX and analogs, most evidence suggests that symbiotic bacteria are the origin of the toxins, although endogenous biosynthesis independent from bacteria has not been excluded. The evolutionary origin of the biosynthetic genes for STX and analogs in dinoflagellates and cyanobacteria remains elusive. These highly potent molecules have been the subject of intensive research since the latter half of the past century; first to study the mode of action of their toxigenicity, and later as tools to characterize the role and structure of NaV channels, and finally as therapeutics. Their pharmacological activities have provided encouragement for their use as therapeutants for ion channel-related pathologies, such as pain control. The functional role in aquatic and terrestrial ecosystems for both groups of toxins is unproven, although plausible mechanisms of ion channel regulation and chemical defense are often invoked. Molecular approaches and the development of improved detection methods will yield deeper understanding of their physiological and ecological roles. This knowledge will facilitate their further biotechnological exploitation and point the way towards

  2. Proteolytic activation of the epithelial sodium channel ENaC in preeclampsia examined with urinary exosomes

    DEFF Research Database (Denmark)

    Nielsen, Maria Ravn; Rytz, Mie; Frederiksen-Møller, Britta

    2015-01-01

    OBJECTIVES: Increased activity of the epithelial sodium channel (ENaC) in the kidneys may explain the coupling between proteinuria, edema, suppressed aldosterone and hypertension in preeclampsia. Preeclamptic women excrete plasminogen-plasmin in urine. In vitro, plasmin increases the activity...... as a positive control for the presence of collecting duct membrane. RESULTS: Urine plasmin-plasminogen/creatinine ratio was increased in the preeclampsia group (p... pregnancy and preeclampsia CONCLUSIONS: It is possible to examine collecting duct transport proteins in urine exosome from pregnant women including γ-ENaC, 2) Urine exosome fraction displays a variable pattern of γ-ENaC signal with a predominance of cleaved forms in both normal and preeclamptic women...

  3. Divergent actions of the pyrethroid insecticides S-bioallethrin, tefluthrin, and deltamethrin on rat Nav1.6 sodium channels

    International Nuclear Information System (INIS)

    Tan Jianguo; Soderlund, David M.

    2010-01-01

    We expressed rat Na v 1.6 sodium channels in combination with the rat β 1 and β 2 auxiliary subunits in Xenopus laevis oocytes and evaluated the effects of the pyrethroid insecticides S-bioallethrin, deltamethrin, and tefluthrin on expressed sodium currents using the two-electrode voltage clamp technique. S-Bioallethrin, a type I structure, produced transient modification evident in the induction of rapidly decaying sodium tail currents, weak resting modification (5.7% modification at 100 μM), and no further enhancement of modification upon repetitive activation by high-frequency trains of depolarizing pulses. By contrast deltamethrin, a type II structure, produced sodium tail currents that were ∼ 9-fold more persistent than those caused by S-bioallethrin, barely detectable resting modification (2.5% modification at 100 μM), and 3.7-fold enhancement of modification upon repetitive activation. Tefluthrin, a type I structure with high mammalian toxicity, exhibited properties intermediate between S-bioallethrin and deltamethrin: intermediate tail current decay kinetics, much greater resting modification (14.1% at 100 μM), and 2.8-fold enhancement of resting modification upon repetitive activation. Comparison of concentration-effect data showed that repetitive depolarization increased the potency of tefluthrin ∼ 15-fold and that tefluthrin was ∼ 10-fold more potent than deltamethrin as a use-dependent modifier of Na v 1.6 sodium channels. Concentration-effect data from parallel experiments with the rat Na v 1.2 sodium channel coexpressed with the rat β 1 and β 2 subunits in oocytes showed that the Na v 1.6 isoform was at least 15-fold more sensitive to tefluthrin and deltamethrin than the Na v 1.2 isoform. These results implicate sodium channels containing the Na v 1.6 isoform as potential targets for the central neurotoxic effects of pyrethroids.

  4. Acid-sensing ion and epithelial sodium channels do not contribute to the mechanoreceptor component of the exercise pressor reflex

    OpenAIRE

    McCord, Jennifer L.; Hayes, Shawn G.; Kaufman, Marc P.

    2008-01-01

    Amiloride, injected into the popliteal artery, has been reported to attenuate the reflex pressor response to static contraction of the triceps surae muscles. Both mechanical and metabolic stimuli arising in contracting skeletal muscle are believed to evoke this effect, which has been named the exercise pressor reflex. Amiloride blocks both acid-sensing ion channels, as well as epithelial sodium channels. Nevertheless, amiloride is thought to block the metabolic stimulus to the reflex, because...

  5. COMMD1 regulates the delta epithelial sodium channel (δENaC) through trafficking and ubiquitination

    International Nuclear Information System (INIS)

    Chang, Tina; Ke, Ying; Ly, Kevin; McDonald, Fiona J.

    2011-01-01

    Highlights: → The COMM domain of COMMD1 mediates binding to δENaC. → COMMD1 reduces the cell surface population of δENaC. → COMMD1 increases the population of δENaC-ubiquitin. → Both endogenous and transfected δENaC localize with COMMD1 and transferrin suggesting they are located in early/recycling endosomes. -- Abstract: The delta subunit of the epithelial sodium channel (δENaC) is a member of the ENaC/degenerin family of ion channels. δENaC is distinct from the related α-, β- and γENaC subunits, known for their role in sodium homeostasis and blood pressure control, as δENaC is expressed in brain neurons and activated by external protons. COMMD1 (copper metabolism Murr1 domain 1) was previously found to associate with and downregulate δENaC activity. Here, we show that COMMD1 interacts with δENaC through its COMM domain. Co-expression of δENaC with COMMD1 significantly reduced δENaC surface expression, and led to an increase in δENaC ubiquitination. Immunocytochemical and confocal microscopy studies show that COMMD1 promoted localization of δENaC to the early/recycling endosomal pool where the two proteins were localized together. These results suggest that COMMD1 downregulates δENaC activity by reducing δENaC surface expression through promoting internalization of surface δENaC to an intracellular recycling pool, possibly via enhanced ubiquitination.

  6. COMMD1 regulates the delta epithelial sodium channel ({delta}ENaC) through trafficking and ubiquitination

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Tina; Ke, Ying; Ly, Kevin [Department of Physiology, University of Otago, P.O. Box 913, Dunedin 9054 (New Zealand); McDonald, Fiona J., E-mail: fiona.mcdonald@otago.ac.nz [Department of Physiology, University of Otago, P.O. Box 913, Dunedin 9054 (New Zealand)

    2011-08-05

    Highlights: {yields} The COMM domain of COMMD1 mediates binding to {delta}ENaC. {yields} COMMD1 reduces the cell surface population of {delta}ENaC. {yields} COMMD1 increases the population of {delta}ENaC-ubiquitin. {yields} Both endogenous and transfected {delta}ENaC localize with COMMD1 and transferrin suggesting they are located in early/recycling endosomes. -- Abstract: The delta subunit of the epithelial sodium channel ({delta}ENaC) is a member of the ENaC/degenerin family of ion channels. {delta}ENaC is distinct from the related {alpha}-, {beta}- and {gamma}ENaC subunits, known for their role in sodium homeostasis and blood pressure control, as {delta}ENaC is expressed in brain neurons and activated by external protons. COMMD1 (copper metabolism Murr1 domain 1) was previously found to associate with and downregulate {delta}ENaC activity. Here, we show that COMMD1 interacts with {delta}ENaC through its COMM domain. Co-expression of {delta}ENaC with COMMD1 significantly reduced {delta}ENaC surface expression, and led to an increase in {delta}ENaC ubiquitination. Immunocytochemical and confocal microscopy studies show that COMMD1 promoted localization of {delta}ENaC to the early/recycling endosomal pool where the two proteins were localized together. These results suggest that COMMD1 downregulates {delta}ENaC activity by reducing {delta}ENaC surface expression through promoting internalization of surface {delta}ENaC to an intracellular recycling pool, possibly via enhanced ubiquitination.

  7. Hydrogen Sulfide Prevents Advanced Glycation End-Products Induced Activation of the Epithelial Sodium Channel

    Directory of Open Access Journals (Sweden)

    Qiushi Wang

    2015-01-01

    Full Text Available Advanced glycation end-products (AGEs are complex and heterogeneous compounds implicated in diabetes. Sodium reabsorption through the epithelial sodium channel (ENaC at the distal nephron plays an important role in diabetic hypertension. Here, we report that H2S antagonizes AGEs-induced ENaC activation in A6 cells. ENaC open probability (PO in A6 cells was significantly increased by exogenous AGEs and that this AGEs-induced ENaC activity was abolished by NaHS (a donor of H2S and TEMPOL. Incubating A6 cells with the catalase inhibitor 3-aminotriazole (3-AT mimicked the effects of AGEs on ENaC activity, but did not induce any additive effect. We found that the expression levels of catalase were significantly reduced by AGEs and both AGEs and 3-AT facilitated ROS uptake in A6 cells, which were significantly inhibited by NaHS. The specific PTEN and PI3K inhibitors, BPV(pic  and LY294002, influence ENaC activity in AGEs-pretreated A6 cells. Moreover, after removal of AGEs from AGEs-pretreated A6 cells for 72 hours, ENaC PO remained at a high level, suggesting that an AGEs-related “metabolic memory” may be involved in sodium homeostasis. Our data, for the first time, show that H2S prevents AGEs-induced ENaC activation by targeting the ROS/PI3K/PTEN pathway.

  8. Modulation of the epithelial sodium channel (ENaC by bacterial metalloproteases and protease inhibitors.

    Directory of Open Access Journals (Sweden)

    Michael B Butterworth

    Full Text Available The serralysin family of metalloproteases is associated with the virulence of multiple gram-negative human pathogens, including Pseudomonas aeruginosa and Serratia marcescens. The serralysin proteases share highly conserved catalytic domains and show evolutionary similarity to the mammalian matrix metalloproteases. Our previous studies demonstrated that alkaline protease (AP from Pseudomonas aeruginosa is capable of activating the epithelial sodium channel (ENaC, leading to an increase in sodium absorption in airway epithelia. The serralysin proteases are often co-expressed with endogenous, intracellular or periplasmic inhibitors, which putatively protect the bacterium from unwanted or unregulated protease activities. To evaluate the potential use of these small protein inhibitors in regulating the serralysin induced activation of ENaC, proteases from Pseudomonas aeruginosa and Serratia marcescens were purified for characterization along with a high affinity inhibitor from Pseudomonas. Both proteases showed activity against in vitro substrates and could be blocked by near stoichiometric concentrations of the inhibitor. In addition, both proteases were capable of activating ENaC when added to the apical surfaces of multiple epithelial cells with similar slow activation kinetics. The high-affinity periplasmic inhibitor from Pseudomonas effectively blocked this activation. These data suggest that multiple metalloproteases are capable of activating ENaC. Further, the endogenous, periplasmic bacterial inhibitors may be useful for modulating the downstream effects of the serralysin virulence factors under physiological conditions.

  9. Sodium channels in axons and glial cells of the optic nerve of Necturus maculosa.

    Science.gov (United States)

    Tang, C M; Strichartz, G R; Orkand, R K

    1979-11-01

    Experiments investigating both the binding of radioactively labelled saxitoxin (STX) and the electrophysiological response to drugs that increase the sodium permeability of excitable membranes were conducted in an effort to detect sodium channels in glial cells of the optic nerve of Necturus maculosa, the mudpuppy. Glial cells in nerves from chronically enucleated animals, which lack optic nerve axons, show no saturable uptake of STX whereas a saturable uptake is clearly present in normal optic nerves. The normal nerve is depolarized by aconitine, batrachotoxin, and veratridine (10(-6)-10(-5) M), whereas the all-glial preparation is only depolarized by veratridine and at concentrations greater than 10(-3) M. Unlike the depolarization caused by veratridine in normal nerves, the response in the all-glial tissue is not blocked by tetrodotoxin nor enhanced by scorpion venom (Leiurus quinquestriatus). In glial cells of the normal nerve, where axons are also present, the addition of 10(-5) M veratridine does lead to a transient depolarization; however, it is much briefer than the axonal response to veratridine in this same tissue. This glial response to veratridine could be caused by the efflux of K+ from the drug-depolarized axons, and is similar to the glial response to extracellular K+ accumulation resulting from action potentials in the axon.

  10. Temperature fluctuation of sodium in annular flow channel heated by single-pin with blockage

    International Nuclear Information System (INIS)

    Miyazaki, Keiji; Kimura, Jiro; Ogawa, Masuro; Okada, Toshio

    1978-01-01

    Root mean square (RMS) value and power spectral density (PSD) of temperature fluctuation were measured with use of forced-circulating sodium in an annular channel (6.5 mm I.D., 20mm O.D.) with concentric disk to simulate blockage (about 80%) of sodium flow. The experimental range of the heat flux was 40 -- 150 W/cm 2 and the bulk flow velocity 0.14--0.41m/sec (Re=7.7x10 3 --2.3x10 4 ) under a temperature of 500--800 0 C. The RMS value measured at the exit of heating section (150mm downstream from the blockage) is larger by a factor of 2 -- 3 than that in the wake (10 -- 20mm downstream from the blockage), marking a few deg.C for a heat flux of 105W/cm 2 and a flow velocity of 0.27m/sec. The RMS value is proportional to the wall-to-bulk-fluid temperature difference in heat transfer, presenting the similar dependence on the heat flux and flow velocity. The fluctuations of temperature are greatly attenuated in the upper unheated section where the radial temperature gradient is absent, and consequently it is suggested that the fluctuations of temperature should be caused by the local turbulence of flow, such as a vortex street due to blockage in the present experiment, under the presence of large gradient of temperature near the heating surface. (auth.)

  11. Gating transitions in the selectivity filter region of a sodium channel are coupled to the domain IV voltage sensor.

    Science.gov (United States)

    Capes, Deborah L; Arcisio-Miranda, Manoel; Jarecki, Brian W; French, Robert J; Chanda, Baron

    2012-02-14

    Voltage-dependent ion channels are crucial for generation and propagation of electrical activity in biological systems. The primary mechanism for voltage transduction in these proteins involves the movement of a voltage-sensing domain (D), which opens a gate located on the cytoplasmic side. A distinct conformational change in the selectivity filter near the extracellular side has been implicated in slow inactivation gating, which is important for spike frequency adaptation in neural circuits. However, it remains an open question whether gating transitions in the selectivity filter region are also actuated by voltage sensors. Here, we examine conformational coupling between each of the four voltage sensors and the outer pore of a eukaryotic voltage-dependent sodium channel. The voltage sensors of these sodium channels are not structurally symmetric and exhibit functional specialization. To track the conformational rearrangements of individual voltage-sensing domains, we recorded domain-specific gating pore currents. Our data show that, of the four voltage sensors, only the domain IV voltage sensor is coupled to the conformation of the selectivity filter region of the sodium channel. Trapping the outer pore in a particular conformation with a high-affinity toxin or disulphide crossbridge impedes the return of this voltage sensor to its resting conformation. Our findings directly establish that, in addition to the canonical electromechanical coupling between voltage sensor and inner pore gates of a sodium channel, gating transitions in the selectivity filter region are also coupled to the movement of a voltage sensor. Furthermore, our results also imply that the voltage sensor of domain IV is unique in this linkage and in the ability to initiate slow inactivation in sodium channels.

  12. Constraint shapes convergence in tetrodotoxin-resistant sodium channels of snakes.

    Science.gov (United States)

    Feldman, Chris R; Brodie, Edmund D; Brodie, Edmund D; Pfrender, Michael E

    2012-03-20

    Natural selection often produces convergent changes in unrelated lineages, but the degree to which such adaptations occur via predictable genetic paths is unknown. If only a limited subset of possible mutations is fixed in independent lineages, then it is clear that constraint in the production or function of molecular variants is an important determinant of adaptation. We demonstrate remarkably constrained convergence during the evolution of resistance to the lethal poison, tetrodotoxin, in six snake species representing three distinct lineages from around the globe. Resistance-conferring amino acid substitutions in a voltage-gated sodium channel, Na(v)1.4, are clustered in only two regions of the protein, and a majority of the replacements are confined to the same three positions. The observed changes represent only a small fraction of the experimentally validated mutations known to increase Na(v)1.4 resistance to tetrodotoxin. These results suggest that constraints resulting from functional tradeoffs between ion channel function and toxin resistance led to predictable patterns of evolutionary convergence at the molecular level. Our data are consistent with theoretical predictions and recent microcosm work that suggest a predictable path is followed during an adaptive walk along a mutational landscape, and that natural selection may be frequently constrained to produce similar genetic outcomes even when operating on independent lineages.

  13. Conotoxins Targeting Neuronal Voltage-Gated Sodium Channel Subtypes: Potential Analgesics?

    Directory of Open Access Journals (Sweden)

    Jeffrey R. McArthur

    2012-11-01

    Full Text Available Voltage-gated sodium channels (VGSC are the primary mediators of electrical signal amplification and propagation in excitable cells. VGSC subtypes are diverse, with different biophysical and pharmacological properties, and varied tissue distribution. Altered VGSC expression and/or increased VGSC activity in sensory neurons is characteristic of inflammatory and neuropathic pain states. Therefore, VGSC modulators could be used in prospective analgesic compounds. VGSCs have specific binding sites for four conotoxin families: μ-, μO-, δ- and ί-conotoxins. Various studies have identified that the binding site of these peptide toxins is restricted to well-defined areas or domains. To date, only the μ- and μO-family exhibit analgesic properties in animal pain models. This review will focus on conotoxins from the μ- and μO-families that act on neuronal VGSCs. Examples of how these conotoxins target various pharmacologically important neuronal ion channels, as well as potential problems with the development of drugs from conotoxins, will be discussed.

  14. Chronic ciguatoxin treatment induces synaptic scaling through voltage gated sodium channels in cortical neurons.

    Science.gov (United States)

    Martín, Víctor; Vale, Carmen; Rubiolo, Juan A; Roel, Maria; Hirama, Masahiro; Yamashita, Shuji; Vieytes, Mercedes R; Botana, Luís M

    2015-06-15

    Ciguatoxins are sodium channels activators that cause ciguatera, one of the most widespread nonbacterial forms of food poisoning, which presents with long-term neurological alterations. In central neurons, chronic perturbations in activity induce homeostatic synaptic mechanisms that adjust the strength of excitatory synapses and modulate glutamate receptor expression in order to stabilize the overall activity. Immediate early genes, such as Arc and Egr1, are induced in response to activity changes and underlie the trafficking of glutamate receptors during neuronal homeostasis. To better understand the long lasting neurological consequences of ciguatera, it is important to establish the role that chronic changes in activity produced by ciguatoxins represent to central neurons. Here, the effect of a 30 min exposure of 10-13 days in vitro (DIV) cortical neurons to the synthetic ciguatoxin CTX 3C on Arc and Egr1 expression was evaluated using real-time polymerase chain reaction approaches. Since the toxin increased the mRNA levels of both Arc and Egr1, the effect of CTX 3C in NaV channels, membrane potential, firing activity, miniature excitatory postsynaptic currents (mEPSCs), and glutamate receptors expression in cortical neurons after a 24 h exposure was evaluated using electrophysiological and western blot approaches. The data presented here show that CTX 3C induced an upregulation of Arc and Egr1 that was prevented by previous coincubation of the neurons with the NaV channel blocker tetrodotoxin. In addition, chronic CTX 3C caused a concentration-dependent shift in the activation voltage of NaV channels to more negative potentials and produced membrane potential depolarization. Moreover, 24 h treatment of cortical neurons with 5 nM CTX 3C decreased neuronal firing and induced synaptic scaling mechanisms, as evidenced by a decrease in the amplitude of mEPSCs and downregulation in the protein level of glutamate receptors that was also prevented by tetrodotoxin

  15. Calmodulin and calcium differentially regulate the neuronal Nav1.1 voltage-dependent sodium channel

    Energy Technology Data Exchange (ETDEWEB)

    Gaudioso, Christelle; Carlier, Edmond; Youssouf, Fahamoe [INSERM U641, Institut Jean Roche, Marseille F-13344 (France); Universite de la Mediterranee, Faculte de Medecine Secteur Nord, IFR 11, Marseille F-13344 (France); Clare, Jeffrey J. [Eaton Pharma Consulting, Eaton Socon, Cambridgeshire PE19 8EF (United Kingdom); Debanne, Dominique [INSERM U641, Institut Jean Roche, Marseille F-13344 (France); Universite de la Mediterranee, Faculte de Medecine Secteur Nord, IFR 11, Marseille F-13344 (France); Alcaraz, Gisele, E-mail: gisele.alcaraz@univmed.fr [INSERM U641, Institut Jean Roche, Marseille F-13344 (France); Universite de la Mediterranee, Faculte de Medecine Secteur Nord, IFR 11, Marseille F-13344 (France)

    2011-07-29

    Highlights: {yields} Both Ca{sup ++}-Calmodulin (CaM) and Ca{sup ++}-free CaM bind to the C-terminal region of Nav1.1. {yields} Ca{sup ++} and CaM have both opposite and convergent effects on I{sub Nav1.1}. {yields} Ca{sup ++}-CaM modulates I{sub Nav1.1} amplitude. {yields} CaM hyperpolarizes the voltage-dependence of activation, and increases the inactivation rate. {yields} Ca{sup ++} alone antagonizes CaM for both effects, and depolarizes the voltage-dependence of inactivation. -- Abstract: Mutations in the neuronal Nav1.1 voltage-gated sodium channel are responsible for mild to severe epileptic syndromes. The ubiquitous calcium sensor calmodulin (CaM) bound to rat brain Nav1.1 and to the human Nav1.1 channel expressed by a stably transfected HEK-293 cell line. The C-terminal region of the channel, as a fusion protein or in the yeast two-hybrid system, interacted with CaM via a consensus C-terminal motif, the IQ domain. Patch clamp experiments on HEK1.1 cells showed that CaM overexpression increased peak current in a calcium-dependent way. CaM had no effect on the voltage-dependence of fast inactivation, and accelerated the inactivation kinetics. Elevating Ca{sup ++} depolarized the voltage-dependence of fast inactivation and slowed down the fast inactivation kinetics, and for high concentrations this effect competed with the acceleration induced by CaM alone. Similarly, the depolarizing action of calcium antagonized the hyperpolarizing shift of the voltage-dependence of activation due to CaM overexpression. Fluorescence spectroscopy measurements suggested that Ca{sup ++} could bind the Nav1.1 C-terminal region with micromolar affinity.

  16. Native pyroglutamation of huwentoxin-IV: a post-translational modification that increases the trapping ability to the sodium channel.

    Science.gov (United States)

    Rong, Mingqiang; Duan, Zhigui; Chen, Juliang; Li, Jianglin; Xiao, Yuchen; Liang, Songping

    2013-01-01

    Huwentoxin-IV (HWTX-IV), a tetrodotoxin-sensitive (TTX-s) sodium channel antagonist, is found in the venom of the Chinese spider Ornithoctonus huwena. A naturally modified HWTX-IV (mHWTX-IV), having a molecular mass 18 Da lower than HWTX-IV, has also been isolated from the venom of the same spider. By a combination of enzymatic fragmentation and MS/MS de novo sequencing, mHWTX-IV has been shown to have the same amino acid sequence as that of HWTX-IV, except that the N-terminal glutamic acid replaced by pyroglutamic acid. mHWTX-IV inhibited tetrodotoxin-sensitive voltage-gated sodium channels of dorsal root ganglion neurons with an IC50 nearly equal to native HWTX-IV. mHWTX-IV showed the same activation and inactivation kinetics seen for native HWTX-IV. In contrast with HWTX-IV, which dissociates at moderate voltage depolarization voltages (+50 mV, 180000 ms), mHWTX-IV inhibition of TTX-sensitive sodium channels is not reversed by strong depolarization voltages (+200 mV, 500 ms). Recovery of Nav1.7current was voltage-dependent and was induced by extreme depolarization in the presence of HWTX-IV, but no obvious current was elicited after application of mHWTX-IV. Our data indicate that the N-terminal modification of HWTX-IV gives the peptide toxin a greater ability to trap the voltage sensor in the sodium channel. Loss of a negative charge, caused by cyclization at the N-terminus, is a possible reason why the modified toxin binds much stronger. To our knowledge, this is the first report of a pyroglutamic acid residue in a spider toxin; this modification seems to increase the trapping ability of the voltage sensor in the sodium channel.

  17. Native pyroglutamation of huwentoxin-IV: a post-translational modification that increases the trapping ability to the sodium channel.

    Directory of Open Access Journals (Sweden)

    Mingqiang Rong

    Full Text Available Huwentoxin-IV (HWTX-IV, a tetrodotoxin-sensitive (TTX-s sodium channel antagonist, is found in the venom of the Chinese spider Ornithoctonus huwena. A naturally modified HWTX-IV (mHWTX-IV, having a molecular mass 18 Da lower than HWTX-IV, has also been isolated from the venom of the same spider. By a combination of enzymatic fragmentation and MS/MS de novo sequencing, mHWTX-IV has been shown to have the same amino acid sequence as that of HWTX-IV, except that the N-terminal glutamic acid replaced by pyroglutamic acid. mHWTX-IV inhibited tetrodotoxin-sensitive voltage-gated sodium channels of dorsal root ganglion neurons with an IC50 nearly equal to native HWTX-IV. mHWTX-IV showed the same activation and inactivation kinetics seen for native HWTX-IV. In contrast with HWTX-IV, which dissociates at moderate voltage depolarization voltages (+50 mV, 180000 ms, mHWTX-IV inhibition of TTX-sensitive sodium channels is not reversed by strong depolarization voltages (+200 mV, 500 ms. Recovery of Nav1.7current was voltage-dependent and was induced by extreme depolarization in the presence of HWTX-IV, but no obvious current was elicited after application of mHWTX-IV. Our data indicate that the N-terminal modification of HWTX-IV gives the peptide toxin a greater ability to trap the voltage sensor in the sodium channel. Loss of a negative charge, caused by cyclization at the N-terminus, is a possible reason why the modified toxin binds much stronger. To our knowledge, this is the first report of a pyroglutamic acid residue in a spider toxin; this modification seems to increase the trapping ability of the voltage sensor in the sodium channel.

  18. Identification of potential novel interaction partners of the sodium-activated potassium channels Slick and Slack in mouse brain.

    Science.gov (United States)

    Rizzi, Sandra; Schwarzer, Christoph; Kremser, Leopold; Lindner, Herbert H; Knaus, Hans-Günther

    2015-12-01

    The sodium-activated potassium channels Slick (Slo2.1, KCNT2) and Slack (Slo2.2, KCNT1) are paralogous channels of the Slo family of high-conductance potassium channels. Slick and Slack channels are widely distributed in the mammalian CNS and they play a role in slow afterhyperpolarization, generation of depolarizing afterpotentials and in setting and stabilizing the resting potential. In the present study we used a combined approach of (co)-immunoprecipitation studies, Western blot analysis, double immunofluorescence and mass spectrometric sequencing in order to investigate protein-protein interactions of the Slick and Slack channels. The data strongly suggest that Slick and Slack channels co-assemble into identical cellular complexes. Double immunofluorescence experiments revealed that Slick and Slack channels co-localize in distinct mouse brain regions. Moreover, we identified the small cytoplasmic protein beta-synuclein and the transmembrane protein 263 (TMEM 263) as novel interaction partners of both, native Slick and Slack channels. In addition, the inactive dipeptidyl-peptidase (DPP 10) and the synapse associated protein 102 (SAP 102) were identified as constituents of the native Slick and Slack channel complexes in the mouse brain. This study presents new insights into protein-protein interactions of native Slick and Slack channels in the mouse brain.

  19. An increase in [Ca2+]i activates basolateral chloride channels and inhibits apical sodium channels in frog skin epithelium

    DEFF Research Database (Denmark)

    Brodin, Birger; Rytved, K A; Nielsen, R

    1996-01-01

    The aim of this study was to investigate the mechanisms by which increases in free cytosolic calcium ([Ca2+]i) cause a decrease in macroscopic sodium absorption across principal cells of the frog skin epithelium. [Ca2+]i was measured with fura-2 in an epifluorescence microscope set-up, sodium abs...

  20. Modulation of epithelial sodium channel (ENaC expression in mouse lung infected with Pseudomonas aeruginosa

    Directory of Open Access Journals (Sweden)

    Radzioch Danuta

    2005-01-01

    Full Text Available Abstract Background The intratracheal instillation of Pseudomonas aeruginosa entrapped in agar beads in the mouse lung leads to chronic lung infection in susceptible mouse strains. As the infection generates a strong inflammatory response with some lung edema, we tested if it could modulate the expression of genes involved in lung liquid clearance, such as the α, β and γ subunits of the epithelial sodium channel (ENaC and the catalytic subunit of Na+-K+-ATPase. Methods Pseudomonas aeruginosa entrapped in agar beads were instilled in the lung of resistant (BalB/c and susceptible (DBA/2, C57BL/6 and A/J mouse strains. The mRNA expression of ENaC and Na+-K+-ATPase subunits was tested in the lung by Northern blot following a 3 hours to 14 days infection. Results The infection of the different mouse strains evoked regulation of α and β ENaC mRNA. Following Pseudomonas instillation, the expression of αENaC mRNA decreased to a median of 43% on days 3 and 7 after infection and was still decreased to a median of 45% 14 days after infection (p 1Na+-K+-ATPase mRNA, the catalytic subunit of the sodium pump, was recorded. The distinctive expression profiles of the three subunits were not different, between the susceptible and resistant mouse strains. Conclusions These results show that Pseudomonas infection, by modulating ENaC subunit expression, could influence edema formation and clearance in infected lungs.

  1. Alterations of sodium and potassium channels of RGCs in RCS rat with the development of retinal degeneration.

    Science.gov (United States)

    Chen, Zhongshan; Song, Yanping; Yao, Junping; Weng, Chuanhuang; Yin, Zheng Qin

    2013-11-01

    All know that retinitis pigmentosa (RP) is a group of hereditary retinal degenerative diseases characterized by progressive dysfunction of photoreceptors and associated with progressive cells loss; nevertheless, little is known about how rods and cones loss affects the surviving inner retinal neurons and networks. Retinal ganglion cells (RGCs) process and convey visual information from retina to visual centers in the brain. The healthy various ion channels determine the normal reception and projection of visual signals from RGCs. Previous work on the Royal College of Surgeons (RCS) rat, as a kind of classical RP animal model, indicated that, at late stages of retinal degeneration in RCS rat, RGCs were also morphologically and functionally affected. Here, retrograde labeling for RGCs with Fluorogold was performed to investigate the distribution, density, and morphological changes of RGCs during retinal degeneration. Then, patch clamp recording, western blot, and immunofluorescence staining were performed to study the channels of sodium and potassium properties of RGCs, so as to explore the molecular and proteinic basis for understanding the alterations of RGCs membrane properties and firing functions. We found that the resting membrane potential, input resistance, and capacitance of RGCs changed significantly at the late stage of retinal degeneration. Action potential could not be evoked in a part of RGCs. Inward sodium current and outward potassium current recording showed that sodium current was impaired severely but only slightly in potassium current. Expressions of sodium channel protein were impaired dramatically at the late stage of retinal degeneration. The results suggested that the density of RGCs decreased, process ramification impaired, and sodium ion channel proteins destructed, which led to the impairment of electrophysiological functions of RGCs and eventually resulted in the loss of visual function.

  2. Convergent Substitutions in a Sodium Channel Suggest Multiple Origins of Toxin Resistance in Poison Frogs.

    Science.gov (United States)

    Tarvin, Rebecca D; Santos, Juan C; O'Connell, Lauren A; Zakon, Harold H; Cannatella, David C

    2016-04-01

    Complex phenotypes typically have a correspondingly multifaceted genetic component. However, the genotype-phenotype association between chemical defense and resistance is often simple: genetic changes in the binding site of a toxin alter how it affects its target. Some toxic organisms, such as poison frogs (Anura: Dendrobatidae), have defensive alkaloids that disrupt the function of ion channels, proteins that are crucial for nerve and muscle activity. Using protein-docking models, we predict that three major classes of poison frog alkaloids (histrionicotoxins, pumiliotoxins, and batrachotoxins) bind to similar sites in the highly conserved inner pore of the muscle voltage-gated sodium channel, Nav1.4. We predict that poison frogs are somewhat resistant to these compounds because they have six types of amino acid replacements in the Nav1.4 inner pore that are absent in all other frogs except for a distantly related alkaloid-defended frog from Madagascar, Mantella aurantiaca. Protein-docking models and comparative phylogenetics support the role of these replacements in alkaloid resistance. Taking into account the four independent origins of chemical defense in Dendrobatidae, phylogenetic patterns of the amino acid replacements suggest that 1) alkaloid resistance in Nav1.4 evolved independently at least seven times in these frogs, 2) variation in resistance-conferring replacements is likely a result of differences in alkaloid exposure across species, and 3) functional constraint shapes the evolution of the Nav1.4 inner pore. Our study is the first to demonstrate the genetic basis of autoresistance in frogs with alkaloid defenses. © The Author 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  3. Essential Oils and Their Constituents Targeting the GABAergic System and Sodium Channels as Treatment of Neurological Diseases

    Directory of Open Access Journals (Sweden)

    Ze-Jun Wang

    2018-05-01

    Full Text Available Essential oils and the constituents in them exhibit different pharmacological activities, such as antinociceptive, anxiolytic-like, and anticonvulsant effects. They are widely applied as a complementary therapy for people with anxiety, insomnia, convulsion, pain, and cognitive deficit symptoms through inhalation, oral administration, and aromatherapy. Recent studies show that essential oils are emerging as a promising source for modulation of the GABAergic system and sodium ion channels. This review summarizes the recent findings regarding the pharmacological properties of essential oils and compounds from the oils and the mechanisms underlying their effects. Specifically, the review focuses on the essential oils and their constituents targeting the GABAergic system and sodium channels, and their antinociceptive, anxiolytic, and anticonvulsant properties. Some constituents target transient receptor potential (TRP channels to exert analgesic effects. Some components could interact with multiple therapeutic target proteins, for example, inhibit the function of sodium channels and, at the same time, activate GABAA receptors. The review concentrates on perspective compounds that could be better candidates for new drug development in the control of pain and anxiety syndromes.

  4. International Union of Basic and Clinical Pharmacology. C. Nomenclature and Properties of Calcium-Activated and Sodium-Activated Potassium Channels.

    Science.gov (United States)

    Kaczmarek, Leonard K; Aldrich, Richard W; Chandy, K George; Grissmer, Stephan; Wei, Aguan D; Wulff, Heike

    2017-01-01

    A subset of potassium channels is regulated primarily by changes in the cytoplasmic concentration of ions, including calcium, sodium, chloride, and protons. The eight members of this subfamily were originally all designated as calcium-activated channels. More recent studies have clarified the gating mechanisms for these channels and have documented that not all members are sensitive to calcium. This article describes the molecular relationships between these channels and provides an introduction to their functional properties. It also introduces a new nomenclature that differentiates between calcium- and sodium-activated potassium channels. Copyright © 2016 by The American Society for Pharmacology and Experimental Therapeutics.

  5. Multiple sodium channel isoforms mediate the pathological effects of Pacific ciguatoxin-1

    Science.gov (United States)

    Inserra, Marco C.; Israel, Mathilde R.; Caldwell, Ashlee; Castro, Joel; Deuis, Jennifer R.; Harrington, Andrea M.; Keramidas, Angelo; Garcia-Caraballo, Sonia; Maddern, Jessica; Erickson, Andelain; Grundy, Luke; Rychkov, Grigori Y.; Zimmermann, Katharina; Lewis, Richard J.; Brierley, Stuart M.; Vetter, Irina

    2017-01-01

    Human intoxication with the seafood poison ciguatoxin, a dinoflagellate polyether that activates voltage-gated sodium channels (NaV), causes ciguatera, a disease characterised by gastrointestinal and neurological disturbances. We assessed the activity of the most potent congener, Pacific ciguatoxin-1 (P-CTX-1), on NaV1.1–1.9 using imaging and electrophysiological approaches. Although P-CTX-1 is essentially a non-selective NaV toxin and shifted the voltage-dependence of activation to more hyperpolarising potentials at all NaV subtypes, an increase in the inactivation time constant was observed only at NaV1.8, while the slope factor of the conductance-voltage curves was significantly increased for NaV1.7 and peak current was significantly increased for NaV1.6. Accordingly, P-CTX-1-induced visceral and cutaneous pain behaviours were significantly decreased after pharmacological inhibition of NaV1.8 and the tetrodotoxin-sensitive isoforms NaV1.7 and NaV1.6, respectively. The contribution of these isoforms to excitability of peripheral C- and A-fibre sensory neurons, confirmed using murine skin and visceral single-fibre recordings, reflects the expression pattern of NaV isoforms in peripheral sensory neurons and their contribution to membrane depolarisation, action potential initiation and propagation. PMID:28225079

  6. Efficacy of sodium channel blockers in SCN2A early infantile epileptic encephalopathy.

    Science.gov (United States)

    Dilena, Robertino; Striano, Pasquale; Gennaro, Elena; Bassi, Laura; Olivotto, Sara; Tadini, Laura; Mosca, Fabio; Barbieri, Sergio; Zara, Federico; Fumagalli, Monica

    2017-04-01

    Recent clinical evidence supports a targeted therapeutic approach for genetic epileptic encephalopathies based on the molecular dysfunction. A 2-day-old male infant presented with epileptic encephalopathy characterized by burst-suppression EEG background and tonic-clonic migrating partial seizures. The condition was refractory to phenobarbital, pyridoxine, pyridoxal phosphate and levetiracetam, but a dramatic response to an intravenous loading dose of phenytoin was documented by video-EEG monitoring. Over weeks phenytoin was successfully switched to carbamazepine to prevent seizure relapses associated with difficulty in maintaining proper blood levels of phenytoin. Genetic analysis identified a novel de novo heterozygous mutation (c.[4633A>G]p.[Met1545Val]) in SCN2A. At two years and three months of age the patient is still seizure-free on carbamazepine, although a developmental delay is evident. Sodium channel blockers represent the first-line treatment for confirmed or suspected SCN2A-related epileptic encephalopathies. In severe cases with compatible electro-clinical features we propose a treatment algorithm based on a test trial with high dose intravenous phenytoin followed in case of a positive response by carbamazepine, more suitable for long-term maintenance treatment. Because of their rarity, collaborative studies are needed to delineate shared therapeutic protocols for EIEE based on the electro-clinical features and the presumed underlying genetic substrate. Copyright © 2016 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.

  7. Nanomolar bifenthrin alters synchronous Ca2+ oscillations and cortical neuron development independent of sodium channel activity.

    Science.gov (United States)

    Cao, Zhengyu; Cui, Yanjun; Nguyen, Hai M; Jenkins, David Paul; Wulff, Heike; Pessah, Isaac N

    2014-04-01

    Bifenthrin, a relatively stable type I pyrethroid that causes tremors and impairs motor activity in rodents, is broadly used. We investigated whether nanomolar bifenthrin alters synchronous Ca(2+) oscillations (SCOs) necessary for activity-dependent dendritic development. Primary mouse cortical neurons were cultured 8 or 9 days in vitro (DIV), loaded with the Ca(2+) indicator Fluo-4, and imaged using a Fluorescence Imaging Plate Reader Tetra. Acute exposure to bifenthrin rapidly increased the frequency of SCOs by 2.7-fold (EC50 = 58 nM) and decreased SCO amplitude by 36%. Changes in SCO properties were independent of modifications in voltage-gated sodium channels since 100 nM bifenthrin had no effect on the whole-cell Na(+) current, nor did it influence neuronal resting membrane potential. The L-type Ca(2+) channel blocker nifedipine failed to ameliorate bifenthrin-triggered SCO activity. By contrast, the metabotropic glutamate receptor (mGluR)5 antagonist MPEP [2-methyl-6-(phenylethynyl)pyridine] normalized bifenthrin-triggered increase in SCO frequency without altering baseline SCO activity, indicating that bifenthrin amplifies mGluR5 signaling independent of Na(+) channel modification. Competitive [AP-5; (-)-2-amino-5-phosphonopentanoic acid] and noncompetitive (dizocilpine, or MK-801 [(5S,10R)-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine maleate]) N-methyl-d-aspartate antagonists partially decreased both basal and bifenthrin-triggered SCO frequency increase. Bifenthrin-modified SCO rapidly enhanced the phosphorylation of cAMP response element-binding protein (CREB). Subacute (48 hours) exposure to bifenthrin commencing 2 DIV-enhanced neurite outgrowth and persistently increased SCO frequency and reduced SCO amplitude. Bifenthrin-stimulated neurite outgrowth and CREB phosphorylation were dependent on mGluR5 activity since MPEP normalized both responses. Collectively these data identify a new mechanism by which bifenthrin potently alters Ca(2

  8. Biophysical and Pharmacological Characterization of Nav1.9 Voltage Dependent Sodium Channels Stably Expressed in HEK-293 Cells.

    Directory of Open Access Journals (Sweden)

    Zhixin Lin

    Full Text Available The voltage dependent sodium channel Nav1.9, is expressed preferentially in peripheral sensory neurons and has been linked to human genetic pain disorders, which makes it target of interest for the development of new pain therapeutics. However, characterization of Nav1.9 pharmacology has been limited due in part to the historical difficulty of functionally expressing recombinant channels. Here we report the successful generation and characterization of human, mouse and rat Nav1.9 stably expressed in human HEK-293 cells. These cells exhibit slowly activating and inactivating inward sodium channel currents that have characteristics of native Nav1.9. Optimal functional expression was achieved by coexpression of Nav1.9 with β1/β2 subunits. While recombinantly expressed Nav1.9 was found to be sensitive to sodium channel inhibitors TC-N 1752 and tetracaine, potency was up to 100-fold less than reported for other Nav channel subtypes despite evidence to support an interaction with the canonical local anesthetic (LA binding region on Domain 4 S6. Nav1.9 Domain 2 S6 pore domain contains a unique lysine residue (K799 which is predicted to be spatially near the local anesthetic interaction site. Mutation of this residue to the consensus asparagine (K799N resulted in an increase in potency for tetracaine, but a decrease for TC-N 1752, suggesting that this residue can influence interaction of inhibitors with the Nav1.9 pore. In summary, we have shown that stable functional expression of Nav1.9 in the widely used HEK-293 cells is possible, which opens up opportunities to better understand channel properties and may potentially aid identification of novel Nav1.9 based pharmacotherapies.

  9. Distinct interactions of Na+ and Ca2+ ions with the selectivity filter of the bacterial sodium channel NaVAb

    International Nuclear Information System (INIS)

    Ke, Song; Zangerl, Eva-Maria; Stary-Weinzinger, Anna

    2013-01-01

    Highlights: ► Ca 2+ translocates slowly in the filter, due to lack of “loose” knock-on mechanism. ► Identification of a high affinity binding site in Na V Ab selectivity filter. ► Changes of EEEE locus triggered by electrostatic interactions with Ca 2+ ions. -- Abstract: Rapid and selective ion transport is essential for the generation and regulation of electrical signaling pathways in living organisms. In this study, we use molecular dynamics simulations and free energy calculations to investigate how the bacterial sodium channel Na V Ab (Arcobacter butzleri) differentiates between Na + and Ca 2+ ions. Multiple nanosecond molecular dynamics simulations revealed distinct binding patterns for these two cations in the selectivity filter and suggested a high affinity calcium binding site formed by backbone atoms of residues Leu-176 and Thr-175 (S CEN ) in the sodium channel selectivity filter

  10. The antipsychotic drug loxapine is an opener of the sodium-activated potassium channel slack (Slo2.2).

    Science.gov (United States)

    Biton, B; Sethuramanujam, S; Picchione, Kelly E; Bhattacharjee, A; Khessibi, N; Chesney, F; Lanneau, C; Curet, O; Avenet, P

    2012-03-01

    Sodium-activated potassium (K(Na)) channels have been suggested to set the resting potential, to modulate slow after-hyperpolarizations, and to control bursting behavior or spike frequency adaptation (Trends Neurosci 28:422-428, 2005). One of the genes that encodes K(Na) channels is called Slack (Kcnt1, Slo2.2). Studies found that Slack channels were highly expressed in nociceptive dorsal root ganglion neurons and modulated their firing frequency (J Neurosci 30:14165-14172, 2010). Therefore, Slack channel openers are of significant interest as putative analgesic drugs. We screened the library of pharmacologically active compounds with recombinant human Slack channels expressed in Chinese hamster ovary cells, by using rubidium efflux measurements with atomic absorption spectrometry. Riluzole at 500 μM was used as a reference agonist. The antipsychotic drug loxapine and the anthelmintic drug niclosamide were both found to activate Slack channels, which was confirmed by using manual patch-clamp analyses (EC(50) = 4.4 μM and EC(50) = 2.9 μM, respectively). Psychotropic drugs structurally related to loxapine were also evaluated in patch-clamp experiments, but none was found to be as active as loxapine. Loxapine properties were confirmed at the single-channel level with recombinant rat Slack channels. In dorsal root ganglion neurons, loxapine was found to behave as an opener of native K(Na) channels and to increase the rheobase of action potential. This study identifies new K(Na) channel pharmacological tools, which will be useful for further Slack channel investigations.

  11. sodium

    International Development Research Centre (IDRC) Digital Library (Canada)

    Les initiatives de réduction de la consommation de sel qui visent l'ensemble de la population et qui ciblent la teneur en sodium des aliments et sensibilisent les consommateurs sont susceptibles de réduire la consommation de sel dans toutes les couches de la population et d'améliorer la santé cardiovasculaire. Ce projet a ...

  12. Two novel sodium channel mutations associated with resistance to indoxacarb and metaflumizone in the diamondback moth, Plutella xylostella.

    Science.gov (United States)

    Wang, Xing-Liang; Su, Wen; Zhang, Jian-Heng; Yang, Yi-Hua; Dong, Ke; Wu, Yi-Dong

    2016-02-01

    Indoxacarb and metaflumizone belong to a relatively new class of sodium channel blocker insecticides (SCBIs). Due to intensive use of indoxacarb, field-evolved indoxacarb resistance has been reported in several lepidopteran pests, including the diamondback moth Plutella xylostella, a serious pest of cruciferous crops. In particular, the BY12 population of P. xylostella, collected from Baiyun, Guangdong Province of China in 2012, was 750-fold more resistant to indoxacarb and 70-fold more resistant to metaflumizone compared with the susceptible Roth strain. Comparison of complementary DNA sequences encoding the sodium channel genes of Roth and BY12 revealed two point mutations (F1845Y and V1848I) in the sixth segment of domain IV of the PxNav protein in the BY population. Both mutations are located within a highly conserved sequence region that is predicted to be involved in the binding sites of local anesthetics and SCBIs based on mammalian sodium channels. A significant correlation was observed among 10 field-collected populations between the mutant allele (Y1845 or I1848) frequencies (1.7% to 52.5%) and resistance levels to both indoxacarb (34- to 870-fold) and metaflumizone (1- to 70-fold). The two mutations were never found to co-exist in the same allele of PxNav , suggesting that they arose independently. This is the first time that sodium channel mutations have been associated with high levels of resistance to SCBIs. F1845Y and V1848I are molecular markers for resistance monitoring in the diamondback moth and possibly other insect pest species. © 2015 Institute of Zoology, Chinese Academy of Sciences.

  13. Predictive 3D modelling of the interactions of pyrethroids with the voltage-gated sodium channels of ticks and mites.

    Science.gov (United States)

    O'Reilly, Andrias O; Williamson, Martin S; González-Cabrera, Joel; Turberg, Andreas; Field, Linda M; Wallace, B A; Davies, T G Emyr

    2014-03-01

    The pyrethroid insecticides are a very successful group of compounds that target invertebrate voltage-gated sodium channels and are widely used in the control of insects, ticks and mites. It is well established that some pyrethroids are good insecticides whereas others are more effective as acaricides. This species specificity is advantageous for controlling particular pest(s) in the presence of another non-target invertebrate, for example controlling the Varroa mite in honeybee colonies. We applied in silico techniques to compare the voltage-gated sodium channels of insects versus ticks and mites and their interactions with a range of pyrethroids and DDT analogues. We identified a single amino acid difference within the pyrethroid binding pocket of ticks/mites that may have significant impact on the effectiveness of pyrethroids as acaricides. Other individual amino acid differences within the binding pocket in distinct tick and mite species may provide a basis for future acaricidal selectivity. Three-dimensional modelling of the pyrethroid/DDT receptor site has led to a new hypothesis to explain the preferential binding of acaricidal pyrethroids to the sodium channels of ticks/mites. This is important for understanding pyrethroid selectivity and the potential effects of mutations that can give rise to resistance to pyrethroids in commercially-important pest species. © 2013 Society of Chemical Industry.

  14. Characterization of the binding of the Ptychodiscus brevis neurotoxin T17 to sodium channels in rat brain synaptosomes

    International Nuclear Information System (INIS)

    Poli, M.A.

    1985-01-01

    The lipid-soluble polyether neurotoxins isolated from the marine dinoflagellate Ptychodiscus brevis (formerly Gymnodinium breve) have been determined to bind to a unique receptor site associated with the voltage-sensitive sodium channel in rat brain synaptosomes. Reduction of the C 42 aldehyde function of T34 to the alcohol function of T17 using NaB 3 H 4 yielded 3 H-T17 with a specific activity of 15 Ci;/mmol. Using this specific probe, binding to sodium channels was measured at 4 0 CC, 22 0 C, and 37 0 C. Rosenthal analysis of the binding data yielded a K/sub d/ of 2.9 nM and B/sub max/ of 6.8 pmoles 3 H-T17 per mg of synaptosomal protein at 4 0 C. Both K/sub d/ and B/sub max/ were found to be temperature dependent. Depolarization of the synaptosomes by osmotic lysis resulted in the loss of 34% of the available receptor sites, with no decrease in binding affinity. Unlabeled T17, T34, and synthetic T17 (reduced T34) were equipotent in their ability to displace 3 H-T17 from its specific receptor site. Competition experiments using natural toxin probes specific for sites I-IV on the voltage-sensitive sodium channel demonstrate that 3 H-T17 does not bind to any of the previously-described neurotoxin receptor sites. A fifth site is proposed

  15. Affinity purification of the voltage-sensitive sodium channel from electroplax with resins selective for sialic acid

    Energy Technology Data Exchange (ETDEWEB)

    James, W.M.; Emerick, M.C.; Agnew, W.S. (Yale Univ. School of medicine, New Haven, CT (USA))

    1989-07-11

    The voltage-sensitive sodium channel present in the eel (Electrophorus electricus) has an unusually high content of sialic acid, including {alpha}-(2{yields}8)-linked polysialic acid, not found in other electroplax membrane glycopeptides. Lectins from Limax flavus (LFA) and wheat germ (WGA) proved the most effective of 11 lectin resins tried. The most selective resin was prepared from IgM antibodies against Neisseria meningitidis {alpha}-(2{yields}8)-polysialic acid which were affinity purified and coupled to Sepharose 4B. The sodium channel was found to bind to WGA, LFA, and IgM resins and was readily eluted with the appropriate soluble carbohydrates. Experiments with LFA and IgM resins demonstrated binding and unbinding rates and displacement kinetics, which suggest highly specific binding at multiple sites on the sodium channel protein. In preparative-scale purification of protein previously fractionated by anion-exchange chromatography, without stabilizing TTX, high yields were reproducibly obtained. Further, when detergent extracts were prepared from electroplax membranes fractionated by low-speed sedimentation, a single step over the IgM resin provided a 70-fold purification, yielding specific activities of 3,200 pmol of ({sup 3}H)TTX-binding sites/mg of protein and a single polypeptide of {approximately}285,000 Da on SDS-acrylamide gels. No small peptides were observed after this 5-h isolation. The authors describe a cation-dependent stabilization with millimolar levels of monovalent and micromolar levels of divalent species.

  16. In vivo potency of different ligands on voltage-gated sodium channels.

    Science.gov (United States)

    Safrany-Fark, Arpad; Petrovszki, Zita; Kekesi, Gabriella; Liszli, Peter; Benedek, Gyorgy; Keresztes, Csilla; Horvath, Gyongyi

    2015-09-05

    The Ranvier nodes of thick myelinated nerve fibers contain almost exclusively voltage-gated sodium channels (Navs), while the unmyelinated fibers have several receptors (e.g., cannabinoid, transient receptor potential vanilloid receptor 1), too. Therefore, a nerve which contains only motor fibers can be an appropriate in vivo model for selective influence of Navs. The goals were to evaluate the potency of local anesthetic drugs on such a nerve in vivo; furthermore, to investigate the effects of ligands with different structures (arachidonic acid, anandamide, capsaicin and nisoxetine) that were proved to inhibit Navs in vitro with antinociceptive properties. The marginal mandibular branch of the facial nerve was explored in anesthetized Wistar rats; after its stimulation, the electrical activity of the vibrissae muscles was registered following the perineural injection of different drugs. Lidocaine, bupivacaine and ropivacaine evoked dose-dependent decrease in electromyographic activity, i.e., lidocaine had lower potency than bupivacaine or ropivacaine. QX-314 did not cause any effect by itself, but its co-application with lidocaine produced a prolonged inhibition. Nisoxetine had a very low potency. While anandamide and capsaicin in high doses caused about 50% decrease in the amplitude of action potential, arachidonic acid did not influence the responses. We proved that the classical local anesthetics have high potency on motor nerves, suggesting that this method might be a reliable model for selective targeting of Navs in vivo circumstances. It is proposed that the effects of these endogenous lipids and capsaicin on sensory fibers are not primarily mediated by Navs. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Characterization of the voltage-gated sodium channel of the Asian citrus psyllid, Diaphorina citri.

    Science.gov (United States)

    Liu, Bin; Coy, Monique R; Wang, Jin-Jun; Stelinski, Lukasz L

    2017-02-01

    The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), is an important insect pest of citrus. It is the vector of 'Candidatus' Liberibacter asiaticus, a phloem-limited bacterium that infects citrus, resulting in the disease Huanglongbing (HLB). Disease management relies heavily on suppression of D. citri populations with insecticides, including pyrethroids. In recent annual surveys to monitor insecticide resistance, reduced susceptibility to fenpropathrin was identified in several field populations of D. citri. The primary target of pyrethroids is the voltage-gated sodium channel (VGSC). The VGSC is prone to target-site insensitivity because of mutations that either reduce pyrethroid binding and/or alter gating kinetics. These mutations, known as knockdown resistance or kdr, have been reported in a wide diversity of arthropod species. Alternative splicing, in combination with kdr mutations, has been also associated with reduced pyrethroid efficacy. Here we report the molecular characterization of the VGSC in D. citri along with a survey of alternative splicing across developmental stages of this species. Previous studies demonstrated that D. citri has an exquisite enzymatic arsenal to detoxify insecticides resulting in reduced efficacy. The results from the current investigation demonstrate that target-site insensitivity is also a potential basis for insecticide resistance to pyrethroids in D. citri. The VGSC sequence and its molecular characterization should facilitate early elucidation of the underlying cause of an established case of resistance to pyrethroids. This is the first characterization of a VGSC from a hemipteran to this level of detail, with the majority of the previous studies on dipterans and lepidopterans. © 2015 Institute of Zoology, Chinese Academy of Sciences.

  18. Domain IV voltage-sensor movement is both sufficient and rate limiting for fast inactivation in sodium channels.

    Science.gov (United States)

    Capes, Deborah L; Goldschen-Ohm, Marcel P; Arcisio-Miranda, Manoel; Bezanilla, Francisco; Chanda, Baron

    2013-08-01

    Voltage-gated sodium channels are critical for the generation and propagation of electrical signals in most excitable cells. Activation of Na(+) channels initiates an action potential, and fast inactivation facilitates repolarization of the membrane by the outward K(+) current. Fast inactivation is also the main determinant of the refractory period between successive electrical impulses. Although the voltage sensor of domain IV (DIV) has been implicated in fast inactivation, it remains unclear whether the activation of DIV alone is sufficient for fast inactivation to occur. Here, we functionally neutralize each specific voltage sensor by mutating several critical arginines in the S4 segment to glutamines. We assess the individual role of each voltage-sensing domain in the voltage dependence and kinetics of fast inactivation upon its specific inhibition. We show that movement of the DIV voltage sensor is the rate-limiting step for both development and recovery from fast inactivation. Our data suggest that activation of the DIV voltage sensor alone is sufficient for fast inactivation to occur, and that activation of DIV before channel opening is the molecular mechanism for closed-state inactivation. We propose a kinetic model of sodium channel gating that can account for our major findings over a wide voltage range by postulating that DIV movement is both necessary and sufficient for fast inactivation.

  19. Mining the Virgin Land of Neurotoxicology: A Novel Paradigm of Neurotoxic Peptides Action on Glycosylated Voltage-Gated Sodium Channels

    Directory of Open Access Journals (Sweden)

    Zhirui Liu

    2012-01-01

    Full Text Available Voltage-gated sodium channels (VGSCs are important membrane protein carrying on the molecular basis for action potentials (AP in neuronal firings. Even though the structure-function studies were the most pursued spots, the posttranslation modification processes, such as glycosylation, phosphorylation, and alternative splicing associating with channel functions captured less eyesights. The accumulative research suggested an interaction between the sialic acids chains and ion-permeable pores, giving rise to subtle but significant impacts on channel gating. Sodium channel-specific neurotoxic toxins, a family of long-chain polypeptides originated from venomous animals, are found to potentially share the binding sites adjacent to glycosylated region on VGSCs. Thus, an interaction between toxin and glycosylated VGSC might hopefully join the campaign to approach the role of glycosylation in modulating VGSCs-involved neuronal network activity. This paper will cover the state-of-the-art advances of researches on glycosylation-mediated VGSCs function and the possible underlying mechanisms of interactions between toxin and glycosylated VGSCs, which may therefore, fulfill the knowledge in identifying the pharmacological targets and therapeutic values of VGSCs.

  20. ASIC and ENaC type sodium channels: conformational states and the structures of the ion selectivity filters.

    Science.gov (United States)

    Hanukoglu, Israel

    2017-02-01

    The acid-sensing ion channels (ASICs) and epithelial sodium channels (ENaC) are members of a superfamily of channels that play critical roles in mechanosensation, chemosensation, nociception, and regulation of blood volume and pressure. These channels look and function like a tripartite funnel that directs the flow of Na + ions into the cytoplasm via the channel pore in the membrane. The subunits that form these channels share a common structure with two transmembrane segments (TM1 and TM2) and a large extracellular part. In most vertebrates, there are five paralogous genes that code for ASICs (ASIC1-ASIC5), and four for ENaC subunits alpha, beta, gamma, and delta (α, β, γ, and δ). While ASICs can form functional channels as a homo- or heterotrimer, ENaC functions as an obligate heterotrimer composed of α-β-γ or β-γ-δ subunits. The structure of ASIC has been determined in several conformations, including desensitized and open states. This review presents a comparison of the structures of these states using easy-to-understand molecular models of the full complex, the central tunnel that includes an outer vestibule, the channel pore, and ion selectivity filter. The differences in the secondary, tertiary, and quaternary structures of the states are summarized to pinpoint the conformational changes responsible for channel opening. Results of site-directed mutagenesis studies of ENaC subunits are examined in light of ASIC1 models. Based on these comparisons, a molecular model for the selectivity filter of ENaC is built by in silico mutagenesis of an ASIC1 structure. These models suggest that Na + ions pass through the filter in a hydrated state. © 2016 Federation of European Biochemical Societies.

  1. Prediction of sodium critical heat flux (CHF) in annular channel using grey systems theory

    International Nuclear Information System (INIS)

    Zhou Tao; Su Guanghui; Zhang Weizhong; Qiu Suizheng; Jia Dounan

    2001-01-01

    Using grey systems theory and experimental data obtained from sodium boiling test loop in China, the grey mutual analysis of some parameters influencing sodium CHF is carried out, and the CHF values are predicted by GM(1, 1) model. The GM(1, h) model is established for CHF prediction, and the predicted CHF values are good agreement with the experimental data

  2. FMRFamide-gated sodium channel and ASIC channels: a new class of ionotropic receptors for FMRFamide and related peptides.

    Science.gov (United States)

    Lingueglia, Eric; Deval, Emmanuel; Lazdunski, Michel

    2006-05-01

    FMRFamide and related peptides typically exert their action through G-protein coupled receptors. However, two ionotropic receptors for these peptides have recently been identified. They are both members of the epithelial amiloride-sensitive Na+ channel and degenerin (ENaC/DEG) family of ion channels. The invertebrate FMRFamide-gated Na+ channel (FaNaC) is a neuronal Na+-selective channel which is directly gated by micromolar concentrations of FMRFamide and related tetrapeptides. Its response is fast and partially desensitizing, and FaNaC has been proposed to participate in peptidergic neurotransmission. On the other hand, mammalian acid-sensing ion channels (ASICs) are not gated but are directly modulated by FMRFamide and related mammalian peptides like NPFF and NPSF. ASICs are activated by external protons and are therefore extracellular pH sensors. They are expressed both in the central and peripheral nervous system and appear to be involved in many physiological and pathophysiological processes such as hippocampal long-term potentiation and defects in learning and memory, acquired fear-related behavior, retinal function, brain ischemia, pain sensation in ischemia and inflammation, taste perception, hearing functions, and mechanoperception. The potentiation of ASIC activity by endogenous RFamide neuropeptides probably participates in the response to noxious acidosis in sensory and central neurons. Available data also raises the possibility of the existence of still unknown FMRFamide related endogenous peptides acting as direct agonists for ASICs.

  3. Developmental regulation of voltage-sensitive sodium channels in rat skeletal muscle

    International Nuclear Information System (INIS)

    Sherman, S.J.

    1985-01-01

    The developmental regulation of the voltage-sensitive Na + channel in rat skeletal muscle was studied in vivo and in vitro. In triceps surae muscle developing in vivo the development of TTX-sensitive Na + channel occurred primarily during the first three postnatal weeks as determined by the specific binding of [ 3 H]saxitoxin. This development proceeded in two separate phases. The first phase occurs independently of continuing motor neuron innervation and accounts for 60% of the adult density of TTX-sensitive Na + channels. The second phase, which begins about day 11, requires innervation. Muscle cells in primary culture were found to have both TTX-sensitive and insensitive Na + channels. The development of the TTX-sensitive channel, in vitro, paralleled the initial innervation-independent phase of development observed in vivo. The density of TTX-sensitive Na + channels in cultured muscle cells was regulated by electrical activity and cytosolic Ca ++ levels. Pharmacological blockade of the spontaneous electrical activity present in these cells lead to a nearly 2-fold increase in the surface density of TTX-sensitive channels. The turnover time of the TTX-sensitive Na + channel was measured by blocking the incorporation of newly synthesized channels with tunicamycin, an inhibitor of N-linked protein glycosylation. The regulation of channel density by electrical activity, cytosolic Ca ++ levels, and agents affecting cyclic neucleotide levels had no effect on the turnover time of the TTX-sensitive Na + channel, indicating that these regulatory agents instead affect the synthesis of the channel

  4. Post-translational modifications of voltage-gated sodium channels in chronic pain syndromes.

    Directory of Open Access Journals (Sweden)

    Cédric James Laedermann

    2015-11-01

    Full Text Available In the peripheral sensory nervous system the neuronal expression of voltage-gated sodium channels (Navs is a very important for the transmission of nociceptive information since they give rise to the upstroke of the action potential. Navs are composed of 9 different isoforms with distinct biophysical properties. Studying the mutations associated with the increase or absence of pain sensitivity in humans, as well as other expression studies, have highlighted Nav1.7, Nav1.8 and Nav1.9 as being the most important contributors to the control of nociceptive neuronal electrogenesis. Modulating their expression and/or function can impact the shape of the action potential and consequently modify pain transmission, a process that is observed in persistent pain conditions.Post-translational modification (PTM of Navs is a well-known process that modifies their expression and function. In chronic pain syndromes, the release of inflammatory molecules into the direct environment of dorsal root ganglia (DRG sensory neurons leads to an abnormal activation of enzymes that induce Navs PTM. The addition of small molecules, i.e. peptides, phosphoryl groups, ubiquitin moieties and/or carbohydrates, can modify the function of Navs in two different ways: via direct physical interference with the subunit of Nav gating, or via the control of Nav trafficking. Both mechanisms have a profound impact on neuronal excitability. In this review we will discuss the role of Protein Kinase A, B and C, Mitogen Activated Protein Kinases and Ca++/Calmodulin-dependent Kinase II in peripheral chronic pain syndromes. We will also discuss more recent findings that the ubiquitination of Nav1.7 by Nedd4-2 and the effect of methylglyoxal on Nav1.8 are also implicated in the development of experimental neuropathic pain. We will address the potential roles of other PTMs in chronic pain and highlight the need for further investigation of PTMs of Navs in order to develop new pharmacological

  5. RNAi-mediated knockdown of the voltage gated sodium ion channel TcNav causes mortality in Tribolium castaneum.

    Science.gov (United States)

    Abd El Halim, Hesham M; Alshukri, Baida M H; Ahmad, Munawar S; Nakasu, Erich Y T; Awwad, Mohammed H; Salama, Elham M; Gatehouse, Angharad M R; Edwards, Martin G

    2016-07-14

    The voltage-gated sodium ion channel (VGSC) belongs to the largest superfamily of ion channels. Since VGSCs play key roles in physiological processes they are major targets for effective insecticides. RNA interference (RNAi) is widely used to analyse gene function, but recently, it has shown potential to contribute to novel strategies for selectively controlling agricultural insect pests. The current study evaluates the delivery of dsRNA targeted to the sodium ion channel paralytic A (TcNav) gene in Tribolium castaneum as a viable means of controlling this insect pest. Delivery of TcNav dsRNA caused severe developmental arrest with larval mortalities up to 73% post injection of dsRNA. Injected larvae showed significant (p < 0.05) knockdown in gene expression between 30-60%. Expression was also significantly (p < 0.05) reduced in pupae following injection causing 30% and 42% knockdown for early and late pupal stages, respectively. Oral delivery of dsRNA caused dose-dependant mortalities of between 19 and 51.34%; this was accompanied by significant (p < 0.05) knockdown in gene expression following 3 days of continuous feeding. The majority of larvae injected with, or fed, dsRNA died during the final larval stage prior to pupation. This work provides evidence of a viable RNAi-based strategy for insect control.

  6. Eslicarbazepine and the enhancement of slow inactivation of voltage-gated sodium channels: a comparison with carbamazepine, oxcarbazepine and lacosamide.

    Science.gov (United States)

    Hebeisen, Simon; Pires, Nuno; Loureiro, Ana I; Bonifácio, Maria João; Palma, Nuno; Whyment, Andrew; Spanswick, David; Soares-da-Silva, Patrício

    2015-02-01

    This study aimed at evaluating the effects of eslicarbazepine, carbamazepine (CBZ), oxcarbazepine (OXC) and lacosamide (LCM) on the fast and slow inactivated states of voltage-gated sodium channels (VGSC). The anti-epileptiform activity was evaluated in mouse isolated hippocampal slices. The anticonvulsant effects were evaluated in MES and the 6-Hz psychomotor tests. The whole-cell patch-clamp technique was used to investigate the effects of eslicarbazepine, CBZ, OXC and LCM on sodium channels endogenously expressed in N1E-115 mouse neuroblastoma cells. CBZ and eslicarbazepine exhibit similar concentration dependent suppression of epileptiform activity in hippocampal slices. In N1E-115 mouse neuroblastoma cells, at a concentration of 250 μM, the voltage dependence of the fast inactivation was not influenced by eslicarbazepine, whereas LCM, CBZ and OXC shifted the V0.5 value (mV) by -4.8, -12.0 and -16.6, respectively. Eslicarbazepine- and LCM-treated fast-inactivated channels recovered similarly to control conditions, whereas CBZ- and OXC-treated channels required longer pulses to recover. CBZ, eslicarbazepine and LCM shifted the voltage dependence of the slow inactivation (V0.5, mV) by -4.6, -31.2 and -53.3, respectively. For eslicarbazepine, LCM, CBZ and OXC, the affinity to the slow inactivated state was 5.9, 10.4, 1.7 and 1.8 times higher than to the channels in the resting state, respectively. In conclusion, eslicarbazepine did not share with CBZ and OXC the ability to alter fast inactivation of VGSC. Both eslicarbazepine and LCM reduce VGSC availability through enhancement of slow inactivation, but LCM demonstrated higher interaction with VGSC in the resting state and with fast inactivation gating. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Synthetic ciguatoxins selectively activate Nav1.8-derived chimeric sodium channels expressed in HEK293 cells.

    Science.gov (United States)

    Yamaoka, Kaoru; Inoue, Masayuki; Miyazaki, Keisuke; Hirama, Masahiro; Kondo, Chie; Kinoshita, Eiji; Miyoshi, Hiroshi; Seyama, Issei

    2009-03-20

    The synthetic ciguatoxin CTX3C has been shown to activate tetrodotoxin (TTX)-sensitive sodium channels (Na(v)1.2, Na(v)1.4, and Na(v)1.5) by accelerating activation kinetics and shifting the activation curve toward hyperpolarization (Yamaoka, K., Inoue, M., Miyahara, H., Miyazaki, K., and Hirama, M. (2004) Br. J. Pharmacol. 142, 879-889). In this study, we further explored the effects of CTX3C on the TTX-resistant sodium channel Na(v)1.8. TTX-resistant channels have been shown to be involved in transducing pain and related sensations (Akopian, A. N., Sivilotti, L., and Wood, J. N. (1996) Nature 379, 257-262). Thus, we hypothesized that ciguatoxin-induced activation of the Na(v)1.8 current would account for the neurological symptoms of ciguatera poisoning. We found that 0.1 mum CTX3C preferentially affected the activation process of the Na(v)1.8 channel compared with those of the Na(v)1.2 and Na(v)1.4 channels. Importantly, without stimulation, 0.1 mum CTX3C induced a large leakage current (I (L)). The conductance of the I (L) calculated relative to the maximum conductance (G (max)) was 10 times larger than that of Na(v)1.2 or Na(v)1.4. To determine the molecular domain of Na(v)1.8 responsible for conferring higher sensitivity to CTX3C, we made two chimeric constructs from Na(v)1.4 and Na(v)1.8. Chimeras containing the N-terminal half of Na(v)1.8 exhibited a large response similar to wild-type Na(v)1.8, indicating that the region conferring high sensitivity to ciguatoxin action is located in the D1 or D2 domains.

  8. Synthetic Ciguatoxins Selectively Activate Nav1.8-derived Chimeric Sodium Channels Expressed in HEK293 Cells*

    Science.gov (United States)

    Yamaoka, Kaoru; Inoue, Masayuki; Miyazaki, Keisuke; Hirama, Masahiro; Kondo, Chie; Kinoshita, Eiji; Miyoshi, Hiroshi; Seyama, Issei

    2009-01-01

    The synthetic ciguatoxin CTX3C has been shown to activate tetrodotoxin (TTX)-sensitive sodium channels (Nav1.2, Nav1.4, and Nav1.5) by accelerating activation kinetics and shifting the activation curve toward hyperpolarization (Yamaoka, K., Inoue, M., Miyahara, H., Miyazaki, K., and Hirama, M. (2004) Br. J. Pharmacol. 142, 879–889). In this study, we further explored the effects of CTX3C on the TTX-resistant sodium channel Nav1.8. TTX-resistant channels have been shown to be involved in transducing pain and related sensations (Akopian, A. N., Sivilotti, L., and Wood, J. N. (1996) Nature 379, 257–262). Thus, we hypothesized that ciguatoxin-induced activation of the Nav1.8 current would account for the neurological symptoms of ciguatera poisoning. We found that 0.1 μm CTX3C preferentially affected the activation process of the Nav1.8 channel compared with those of the Nav1.2 and Nav1.4 channels. Importantly, without stimulation, 0.1 μm CTX3C induced a large leakage current (IL). The conductance of the IL calculated relative to the maximum conductance (Gmax) was 10 times larger than that of Nav1.2 or Nav1.4. To determine the molecular domain of Nav1.8 responsible for conferring higher sensitivity to CTX3C, we made two chimeric constructs from Nav1.4 and Nav1.8. Chimeras containing the N-terminal half of Nav1.8 exhibited a large response similar to wild-type Nav1.8, indicating that the region conferring high sensitivity to ciguatoxin action is located in the D1 or D2 domains. PMID:19164297

  9. Influence of water-soluble channeling agents on the release of diclofenac sodium from Irvingia malayana wax matrix tablets.

    Science.gov (United States)

    Yotsawimonwat, Songwut; Charumanee, Suporn; Kaewvichit, Sayam; Sirithunyalug, Jakkapan; Sirisa-Ard, Panee; Piyamongkol, Sirivipa; Siangwong, Kulthawat

    2017-05-01

    Irvingia malayana wax (IW) is majorly composed of esters of medium chain fatty acids. Its melting point is low and closed to the body temperature. This study aimed at investigating the potential of IW as a matrix-forming agent and evaluate the effect of soluble channeling agents on the release of diclofenac sodium (DS) from IW matrix tablets. The preformulation study by infrared spectroscopy and differential scanning calorimetry showed no incompatibility between IW and DS or soluble channeling agents, namely PEG 4000, PEG 6000 and lactose. IW retarded the release of DS from the matrix tablets more efficiently than carnauba wax due to its greater hydrophobicity and its ability to become partial molten wax at 37° C. Factors affecting the release of DS from IW matrix were drug concentrations, and types and concentrations of channeling agents. The release of DS significantly improved when DS concentration reached approximately 33%. The fast dissolving channeling agent, lactose, could enhance the drug release rate more effectively than PEG 4000 and PEG 6000, respectively. The linear relationship between the DS release rate and the concentration of the chosen channeling agent, PEG 6000, was found (r 2 =0.9866).

  10. Regulation of sodium channel function by bilayer elasticity: the importance of hydrophobic coupling. Effects of Micelle-forming amphiphiles and cholesterol

    DEFF Research Database (Denmark)

    Lundbæk, Jens August; Birn, Pia; Hansen, Anker J

    2004-01-01

    , Triton X-100, and reduced Triton X-100) that make lipid bilayers less "stiff", as measured using gA channels, shift the voltage dependence of sodium channel inactivation toward more hyperpolarized potentials. At low amphiphile concentration, the magnitude of the shift is linearly correlated to the change...

  11. Parallel evolution of tetrodotoxin resistance in three voltage-gated sodium channel genes in the garter snake Thamnophis sirtalis.

    Science.gov (United States)

    McGlothlin, Joel W; Chuckalovcak, John P; Janes, Daniel E; Edwards, Scott V; Feldman, Chris R; Brodie, Edmund D; Pfrender, Michael E; Brodie, Edmund D

    2014-11-01

    Members of a gene family expressed in a single species often experience common selection pressures. Consequently, the molecular basis of complex adaptations may be expected to involve parallel evolutionary changes in multiple paralogs. Here, we use bacterial artificial chromosome library scans to investigate the evolution of the voltage-gated sodium channel (Nav) family in the garter snake Thamnophis sirtalis, a predator of highly toxic Taricha newts. Newts possess tetrodotoxin (TTX), which blocks Nav's, arresting action potentials in nerves and muscle. Some Thamnophis populations have evolved resistance to extremely high levels of TTX. Previous work has identified amino acid sites in the skeletal muscle sodium channel Nav1.4 that confer resistance to TTX and vary across populations. We identify parallel evolution of TTX resistance in two additional Nav paralogs, Nav1.6 and 1.7, which are known to be expressed in the peripheral nervous system and should thus be exposed to ingested TTX. Each paralog contains at least one TTX-resistant substitution identical to a substitution previously identified in Nav1.4. These sites are fixed across populations, suggesting that the resistant peripheral nerves antedate resistant muscle. In contrast, three sodium channels expressed solely in the central nervous system (Nav1.1-1.3) showed no evidence of TTX resistance, consistent with protection from toxins by the blood-brain barrier. We also report the exon-intron structure of six Nav paralogs, the first such analysis for snake genes. Our results demonstrate that the molecular basis of adaptation may be both repeatable across members of a gene family and predictable based on functional considerations. © The Author 2014. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  12. Characterization of the binding of the Ptychodiscus brevis neurotoxin T17 to sodium channels in rat brain synaptosomes

    Energy Technology Data Exchange (ETDEWEB)

    Poli, M.A.

    1985-01-01

    The lipid-soluble polyether neurotoxins isolated from the marine dinoflagellate Ptychodiscus brevis (formerly Gymnodinium breve) have been determined to bind to a unique receptor site associated with the voltage-sensitive sodium channel in rat brain synaptosomes. Reduction of the C/sub 42/ aldehyde function of T34 to the alcohol function of T17 using NaB/sup 3/H/sub 4/ yielded /sup 3/H-T17 with a specific activity of 15 Ci;/mmol. Using this specific probe, binding to sodium channels was measured at 4/sup 0/CC, 22/sup 0/C, and 37/sup 0/C. Rosenthal analysis of the binding data yielded a K/sub d/ of 2.9 nM and B/sub max/ of 6.8 pmoles /sup 3/H-T17 per mg of synaptosomal protein at 4/sup 0/C. Both K/sub d/ and B/sub max/ were found to be temperature dependent. Depolarization of the synaptosomes by osmotic lysis resulted in the loss of 34% of the available receptor sites, with no decrease in binding affinity. Unlabeled T17, T34, and synthetic T17 (reduced T34) were equipotent in their ability to displace /sup 3/H-T17 from its specific receptor site. Competition experiments using natural toxin probes specific for sites I-IV on the voltage-sensitive sodium channel demonstrate that /sup 3/H-T17 does not bind to any of the previously-described neurotoxin receptor sites. A fifth site is proposed.

  13. A SCN9A gene-encoded dorsal root ganglia sodium channel polymorphism associated with severe fibromyalgia

    Directory of Open Access Journals (Sweden)

    Vargas-Alarcon Gilberto

    2012-02-01

    Full Text Available Abstract Background A consistent line of investigation suggests that autonomic nervous system dysfunction may explain the multi-system features of fibromyalgia (FM; and that FM is a sympathetically maintained neuropathic pain syndrome. Dorsal root ganglia (DRG are key sympathetic-nociceptive short-circuit sites. Sodium channels located in DRG (particularly Nav1.7 act as molecular gatekeepers for pain detection. Nav1.7 is encoded in gene SCN9A of chromosome 2q24.3 and is predominantly expressed in the DRG pain-sensing neurons and sympathetic ganglia neurons. Several SCN9A sodium channelopathies have been recognized as the cause of rare painful dysautonomic syndromes such as paroxysmal extreme pain disorder and primary erythromelalgia. The aim of this study was to search for an association between fibromyalgia and several SCN9A sodium channels gene polymorphisms. Methods We studied 73 Mexican women suffering from FM and 48 age-matched women who considered themselves healthy. All participants filled out the Fibromyalgia Impact Questionnaire (FIQ. Genomic DNA from whole blood containing EDTA was extracted by standard techniques. The following SCN9A single-nucleotide polymorphisms (SNP were determined by 5' exonuclease TaqMan assays: rs4371369; rs4387806; rs4453709; rs4597545; rs6746030; rs6754031; rs7607967; rs12620053; rs12994338; and rs13017637. Results The frequency of the rs6754031 polymorphism was significantly different in both groups (P = 0.036 mostly due to an absence of the GG genotype in controls. Interestingly; patients with this rs6754031 GG genotype had higher FIQ scores (median = 80; percentile 25/75 = 69/88 than patients with the GT genotype (median = 63; percentile 25/75 = 58/73; P = 0.002 and the TT genotype (median = 71; percentile 25/75 = 64/77; P = 0.001. Conclusion In this ethnic group; a disabling form of FM is associated to a particular SCN9A sodium channel gene variant. These preliminary results raise the possibility that

  14. Spontaneous and CRH-Induced Excitability and Calcium Signaling in Mice Corticotrophs Involves Sodium, Calcium, and Cation-Conducting Channels

    Czech Academy of Sciences Publication Activity Database

    Zemková, Hana; Tomič, M.; Kučka, M.; Aguilera, G.; Stojilkovic, S. S.

    2016-01-01

    Roč. 157, č. 4 (2016), s. 1576-1589 ISSN 0013-7227 R&D Projects: GA ČR(CZ) GBP304/12/G069; GA MŠk(CZ) LQ1604; GA MŠk(CZ) ED1.1.00/02.0109 Institutional support: RVO:67985823 Keywords : action potential * background sodium conductance * bursting activity * cation -conducting channels * cytosolic calcium concentration * resting membrane potential Subject RIV: FB - Endocrinology, Diabetology, Metabolism, Nutrition Impact factor: 4.286, year: 2016

  15. Cardiac sodium channel NaV1.5 distribution in myocytes via interacting proteins: the multiple pool model.

    Science.gov (United States)

    Shy, Diana; Gillet, Ludovic; Abriel, Hugues

    2013-04-01

    The cardiac sodium current (INa) is responsible for the rapid depolarization of cardiac cells, thus allowing for their contraction. It is also involved in regulating the duration of the cardiac action potential (AP) and propagation of the impulse throughout the myocardium. Cardiac INa is generated by the voltage-gated Na(+) channel, NaV1.5, a 2016-residue protein which forms the pore of the channel. Over the past years, hundreds of mutations in SCN5A, the human gene coding for NaV1.5, have been linked to many cardiac electrical disorders, including the congenital and acquired long QT syndrome, Brugada syndrome, conduction slowing, sick sinus syndrome, atrial fibrillation, and dilated cardiomyopathy. Similar to many membrane proteins, NaV1.5 has been found to be regulated by several interacting proteins. In some cases, these different proteins, which reside in distinct membrane compartments (i.e. lateral membrane vs. intercalated disks), have been shown to interact with the same regulatory domain of NaV1.5, thus suggesting that several pools of NaV1.5 channels may co-exist in cardiac cells. The aim of this review article is to summarize the recent works that demonstrate its interaction with regulatory proteins and illustrate the model that the sodium channel NaV1.5 resides in distinct and different pools in cardiac cells. This article is part of a Special Issue entitled: Cardiomyocyte Biology: Cardiac Pathways of Differentiation, Metabolism and Contraction. Copyright © 2012 Elsevier B.V. All rights reserved.

  16. Sodium channel SCN8A (Nav1.6: properties and de novo mutations in epileptic encephalopathy and intellectual disability

    Directory of Open Access Journals (Sweden)

    Janelle Elizabeth O'Brien

    2013-10-01

    Full Text Available The sodium channel Nav1.6, encoded by the gene SCN8A, is one of the major voltage-gated channels in human brain. The sequences of sodium channels have been highly conserved during evolution, and minor changes in biophysical properties can have a major impact in vivo. Insight into the role of Nav1.6 has come from analysis of spontaneous and induced mutations of mouse Scn8a during the past 18 years. Only within the past year has the role of SCN8A in human disease become apparent from whole exome and genome sequences of patients with sporadic disease. Unique features of Nav1.6 include its contribution to persistent current, resurgent current, repetitive neuronal firing, and subcellular localization at the axon initial segment and nodes of Ranvier. Loss of Nav1.6 activity results in reduced neuronal excitability, while gain-of-function mutations can increase neuronal excitability. Mouse Scn8a (med mutants exhibit movement disorders including ataxia, tremor and dystonia. Thus far, more than ten human de novo mutations have been identified in patients with two types of disorders, epileptic encephalopathy and intellectual disability. We review these human mutations as well as the unique features of Nav1.6 that contribute to its role in determining neuronal excitability in vivo. A supplemental figure illustrating the positions of amino acid residues within the 4 domains and 24 transmembrane segments of Nav1.6 is provided to facilitate the location of novel mutations within the channel protein.

  17. Structure of a prokaryotic sodium channel pore reveals essential gating elements and an outer ion binding site common to eukaryotic channels.

    Science.gov (United States)

    Shaya, David; Findeisen, Felix; Abderemane-Ali, Fayal; Arrigoni, Cristina; Wong, Stephanie; Nurva, Shailika Reddy; Loussouarn, Gildas; Minor, Daniel L

    2014-01-23

    Voltage-gated sodium channels (NaVs) are central elements of cellular excitation. Notwithstanding advances from recent bacterial NaV (BacNaV) structures, key questions about gating and ion selectivity remain. Here, we present a closed conformation of NaVAe1p, a pore-only BacNaV derived from NaVAe1, a BacNaV from the arsenite oxidizer Alkalilimnicola ehrlichei found in Mono Lake, California, that provides insight into both fundamental properties. The structure reveals a pore domain in which the pore-lining S6 helix connects to a helical cytoplasmic tail. Electrophysiological studies of full-length BacNaVs show that two elements defined by the NaVAe1p structure, an S6 activation gate position and the cytoplasmic tail "neck", are central to BacNaV gating. The structure also reveals the selectivity filter ion entry site, termed the "outer ion" site. Comparison with mammalian voltage-gated calcium channel (CaV) selectivity filters, together with functional studies, shows that this site forms a previously unknown determinant of CaV high-affinity calcium binding. Our findings underscore commonalities between BacNaVs and eukaryotic voltage-gated channels and provide a framework for understanding gating and ion permeation in this superfamily. © 2013. Published by Elsevier Ltd. All rights reserved.

  18. TWIK-1 two-pore domain potassium channels change ion selectivity and conduct inward leak sodium currents in hypokalemia.

    Science.gov (United States)

    Ma, Liqun; Zhang, Xuexin; Chen, Haijun

    2011-06-07

    Background potassium (K+) channels, which are normally selectively permeable to K+, maintain the cardiac resting membrane potential at around -80 mV. In subphysiological extracellular K+ concentrations ([K+]o), which occur in pathological hypokalemia, the resting membrane potential of human cardiomyocytes can depolarize to around -50 mV, whereas rat and mouse cardiomyocytes become hyperpolarized, consistent with the Nernst equation for K+. This paradoxical depolarization of cardiomyocytes in subphysiological [K+]o, which may contribute to cardiac arrhythmias, is thought to involve an inward leak sodium (Na+) current. Here, we show that human cardiac TWIK-1 (also known as K2P1) two-pore domain K+ channels change ion selectivity, becoming permeable to external Na+, and conduct inward leak Na+ currents in subphysiological [K+]o. A specific threonine residue (Thr118) within the pore selectivity sequence TxGYG was required for this altered ion selectivity. Mouse cardiomyocyte-derived HL-1 cells exhibited paradoxical depolarization with ectopic expression of TWIK-1 channels, whereas TWIK-1 knockdown in human spherical primary cardiac myocytes eliminated paradoxical depolarization. These findings indicate that ion selectivity of TWIK-1 K+ channels changes during pathological hypokalemia, elucidate a molecular basis for inward leak Na+ currents that could trigger or contribute to cardiac paradoxical depolarization in lowered [K+]o, and identify a mechanism for regulating cardiac excitability.

  19. Mitochondria-derived superoxide and voltage-gated sodium channels in baroreceptor neurons from chronic heart-failure rats.

    Science.gov (United States)

    Tu, Huiyin; Liu, Jinxu; Zhu, Zhen; Zhang, Libin; Pipinos, Iraklis I; Li, Yu-Long

    2012-01-01

    Our previous study has shown that chronic heart failure (CHF) reduces expression and activation of voltage-gated sodium (Na(v)) channels in baroreceptor neurons, which are involved in the blunted baroreceptor neuron excitability and contribute to the impairment of baroreflex in the CHF state. The present study examined the role of mitochondria-derived superoxide in the reduced Na(v) channel function in coronary artery ligation-induced CHF rats. CHF decreased the protein expression and activity of mitochondrial complex enzymes and manganese SOD (MnSOD) and elevated the mitochondria-derived superoxide level in the nodose neurons compared with those in sham nodose neurons. Adenoviral MnSOD (Ad.MnSOD) gene transfection (50 multiplicity of infection) into the nodose neurons normalized the MnSOD expression and reduced the elevation of mitochondrial superoxide in the nodose neurons from CHF rats. Ad.MnSOD also partially reversed the reduced protein expression and current density of the Na(v) channels and the suppressed cell excitability (the number of action potential and the current threshold for inducing action potential) in aortic baroreceptor neurons from CHF rats. Data from the present study indicate that mitochondrial dysfunction, including decreased protein expression and activity of mitochondrial complex enzymes and MnSOD and elevated mitochondria-derived superoxide, contributes to the reduced Na(v) channel activation and cell excitability in the aortic baroreceptor neurons in CHF rats.

  20. Systematic Study of Binding of μ-Conotoxins to the Sodium Channel NaV1.4

    Directory of Open Access Journals (Sweden)

    Somayeh Mahdavi

    2014-12-01

    Full Text Available Voltage-gated sodium channels (NaV are fundamental components of the nervous system. Their dysfunction is implicated in a number of neurological disorders, such as chronic pain, making them potential targets for the treatment of such disorders. The prominence of the NaV channels in the nervous system has been exploited by venomous animals for preying purposes, which have developed toxins that can block the NaV channels, thereby disabling their function. Because of their potency, such toxins could provide drug leads for the treatment of neurological disorders associated with NaV channels. However, most toxins lack selectivity for a given target NaV channel, and improving their selectivity profile among the NaV1 isoforms is essential for their development as drug leads. Computational methods will be very useful in the solution of such design problems, provided accurate models of the protein-ligand complex can be constructed. Using docking and molecular dynamics simulations, we have recently constructed a model for the NaV1.4-μ-conotoxin-GIIIA complex and validated it with the ample mutational data available for this complex. Here, we use the validated NaV1.4 model in a systematic study of binding other μ-conotoxins (PIIIA, KIIIA and BuIIIB to NaV1.4. The binding mode obtained for each complex is shown to be consistent with the available mutation data and binding constants. We compare the binding modes of PIIIA, KIIIA and BuIIIB to that of GIIIA and point out the similarities and differences among them. The detailed information about NaV1.4-μ-conotoxin interactions provided here will be useful in the design of new NaV channel blocking peptides.

  1. Molecular cloning and analysis of zebrafish voltage-gated sodium channel beta subunit genes: implications for the evolution of electrical signaling in vertebrates

    Directory of Open Access Journals (Sweden)

    Zhong Tao P

    2007-07-01

    Full Text Available Abstract Background Action potential generation in excitable cells such as myocytes and neurons critically depends on voltage-gated sodium channels. In mammals, sodium channels exist as macromolecular complexes that include a pore-forming alpha subunit and 1 or more modulatory beta subunits. Although alpha subunit genes have been cloned from diverse metazoans including flies, jellyfish, and humans, beta subunits have not previously been identified in any non-mammalian species. To gain further insight into the evolution of electrical signaling in vertebrates, we investigated beta subunit genes in the teleost Danio rerio (zebrafish. Results We identified and cloned single zebrafish gene homologs for beta1-beta3 (zbeta1-zbeta3 and duplicate genes for beta4 (zbeta4.1, zbeta4.2. Sodium channel beta subunit loci are similarly organized in fish and mammalian genomes. Unlike their mammalian counterparts, zbeta1 and zbeta2 subunit genes display extensive alternative splicing. Zebrafish beta subunit genes and their splice variants are differentially-expressed in excitable tissues, indicating tissue-specific regulation of zbeta1-4 expression and splicing. Co-expression of the genes encoding zbeta1 and the zebrafish sodium channel alpha subunit Nav1.5 in Chinese Hamster Ovary cells increased sodium current and altered channel gating, demonstrating functional interactions between zebrafish alpha and beta subunits. Analysis of the synteny and phylogeny of mammalian, teleost, amphibian, and avian beta subunit and related genes indicated that all extant vertebrate beta subunits are orthologous, that beta2/beta4 and beta1/beta3 share common ancestry, and that beta subunits are closely related to other proteins sharing the V-type immunoglobulin domain structure. Vertebrate sodium channel beta subunit genes were not identified in the genomes of invertebrate chordates and are unrelated to known subunits of the para sodium channel in Drosophila. Conclusion The

  2. Intron retention in mRNA encoding ancillary subunit of insect voltage-gated sodium channel modulates channel expression, gating regulation and drug sensitivity.

    Directory of Open Access Journals (Sweden)

    Céline M Bourdin

    Full Text Available Insect voltage-gated sodium (Nav channels are formed by a well-known pore-forming α-subunit encoded by para-like gene and ancillary subunits related to TipE from the mutation "temperature-induced-paralysis locus E." The role of these ancillary subunits in the modulation of biophysical and pharmacological properties of Na(+ currents are not enough documented. The unique neuronal ancillary subunit TipE-homologous protein 1 of Drosophila melanogaster (DmTEH1 strongly enhances the expression of insect Nav channels when heterologously expressed in Xenopus oocytes. Here we report the cloning and functional expression of two neuronal DmTEH1-homologs of the cockroach, Periplaneta americana, PaTEH1A and PaTEH1B, encoded by a single bicistronic gene. In PaTEH1B, the second exon encoding the last 11-amino-acid residues of PaTEH1A is shifted to 3'UTR by the retention of a 96-bp intron-containing coding-message, thus generating a new C-terminal end. We investigated the gating and pharmacological properties of the Drosophila Nav channel variant (DmNav1-1 co-expressed with DmTEH1, PaTEH1A, PaTEH1B or a truncated mutant PaTEH1Δ(270-280 in Xenopus oocytes. PaTEH1B caused a 2.2-fold current density decrease, concomitant with an equivalent α-subunit incorporation decrease in the plasma membrane, compared to PaTEH1A and PaTEH1Δ(270-280. PaTEH1B positively shifted the voltage-dependences of activation and slow inactivation of DmNav1-1 channels to more positive potentials compared to PaTEH1A, suggesting that the C-terminal end of both proteins may influence the function of the voltage-sensor and the pore of Nav channel. Interestingly, our findings showed that the sensitivity of DmNav1-1 channels to lidocaine and to the pyrazoline-type insecticide metabolite DCJW depends on associated TEH1-like subunits. In conclusion, our work demonstrates for the first time that density, gating and pharmacological properties of Nav channels expressed in Xenopus oocytes can be

  3. [Mechanism of action of neurotoxins acting on the inactivation of voltage-gated sodium channels].

    Science.gov (United States)

    Benoit, E

    1998-01-01

    This review focuses on the mechanism(s) of action of neurotoxins acting on the inactivation of voltage-gated Na channels. Na channels are transmembrane proteins which are fundamental for cellular communication. These proteins form pores in the plasma membrane allowing passive ionic movements to occur. Their opening and closing are controlled by gating systems which depend on both membrane potential and time. Na channels have three functional properties, mainly studied using electrophysiological and biochemical techniques, to ensure their role in the generation and propagation of action potentials: 1) a highly selectivity for Na ions, 2) a rapid opening ("activation"), responsible for the depolarizing phase of the action potential, and 3) a late closing ("inactivation") involved in the repolarizing phase of the action potential. As an essential protein for membrane excitability, the Na channel is the specific target of a number of vegetal and animal toxins which, by binding to the channel, alter its activity by affecting one or more of its properties. At least six toxin receptor sites have been identified on the neuronal Na channel on the basis of binding studies. However, only toxins interacting with four of these sites (sites 2, 3, 5 et 6) produce alterations of channel inactivation. The maximal percentage of Na channels modified by the binding of neurotoxins to sites 2 (batrachotoxin and some alkaloids), 3 (alpha-scorpion and sea anemone toxins), 5 (brevetoxins and ciguatoxins) et 6 (delta-conotoxins) is different according to the site considered. However, in all cases, these channels do not inactivate. Moreover, Na channels modified by toxins which bind to sites 2, 5 and 6 activate at membrane potentials more negative than do unmodified channels. The physiological consequences of Na channel modifications, induced by the binding of neurotoxins to sites 2, 3, 5 and 6, are (i) an inhibition of cellular excitability due to an important membrane depolarization (site

  4. Salt-Induced Hypertension in a Mouse Model of Liddle's Syndrome is Mediated by Epithelial Sodium Channels in the Brain

    Science.gov (United States)

    Van Huysse, James W.; Amin, Md. Shahrier; Yang, Baoli; Leenen, Frans H. H.

    2012-01-01

    Neural precursor cell expressed and developmentally downregulated 4-2 protein (Nedd4-2) facilitates the endocytosis of epithelial Na channels (ENaC). Both mice and humans with a loss of regulation of ENaC by Nedd4-2 have salt-induced hypertension. ENaC is also expressed in the brain, where it is critical for hypertension on high salt diet in salt-sensitive rats. In the present studies we assessed whether Nedd4-2 knockout (−/−) mice have: 1) increased brain ENaC; 2) elevated CSF sodium on high salt diet; and 3) enhanced pressor responses to CSF sodium and hypertension on high salt diet, both mediated by brain ENaC. Prominent choroid plexus and neuronal ENaC staining was present in −/− but not in wild-type (W/T) mice. In chronically instrumented mice, intracerebroventricular (icv) infusion of Na-rich aCSF increased MAP 3-fold higher in −/− than W/T. Icv infusion of the ENaC blocker benzamil abolished this enhancement. In telemetered −/− mice on high salt diet (8% NaCl), CSF [Na+], MAP and HR increased significantly, MAP by 30-35 mmHg. These MAP and HR responses were largely prevented by icv benzamil, but only to a minor extent by sc benzamil at the icv rate. We conclude that increased ENaC expression in the brain of Nedd 4-2 −/− mice mediates their hypertensive response to high salt diet, by causing increased sodium levels in the CSF as well as hyper-responsiveness to CSF sodium. These findings highlight the possible causative contribution of CNS ENaC in the etiology of salt-induced hypertension. PMID:22802227

  5. The sodium channel activator Lu AE98134 normalizes the altered firing properties of fast spiking interneurons in Dlx5/6+/- mice

    DEFF Research Database (Denmark)

    von Schoubye, Nadia Lybøl; Frederiksen, Kristen; Kristiansen, Uffe

    2018-01-01

    Mental disorders such as schizophrenia are associated with impaired firing properties of fast spiking inhibitory interneurons (FSINs) causing reduced task-evoked gamma-oscillation in prefrontal cortex. The voltage-gated sodium channel NaV1.1 is highly expressed in PV-positive interneurons, but only...... at low levels in principal cells. Positive modulators of Nav1.1 channels are for this reason considered potential candidates for the treatment of cognitive disorders. Here we examined the effect of the novel positive modulator of voltage-gated sodium channels Lu AE98134. We found that Lu AE98134...... facilitated the sodium current mediated by NaV1.1 expressed in HEK cells by shifting its activation to more negative values, decreasing its inactivation kinetics and promoting a persistent inward current. In a slice preparation from the brain of adult mice, Lu AE98134 promoted the excitability of fast spiking...

  6. Neuroplastic alteration of TTX-resistant sodium channel with visceral pain and morphine-induced hyperalgesia

    Directory of Open Access Journals (Sweden)

    Chen J

    2012-11-01

    Full Text Available Jinghong Chen,1,2,4 Ze-hui Gong,4 Hao Yan,2 Zhijun Qiao,3 Bo-yi Qin41Department of Internal Medicine, Neuroscience Program, The University of Texas Medical Branch, Galveston, TX, USA; 2The Divisions of Pharmacy, Pharmacology core lab, MD Anderson Cancer Center, Houston, TX, USA; 3University of Texas-Pan American, Edinburg, TX, USA; 4Beijing Institute of Pharmacology and Toxicology, Beijing, China Abstract: The discovery of the tetrodotoxin-resistant (TTX-R Na+ channel in nociceptive neurons has provided a special target for analgesic intervention. In a previous study we found that both morphine tolerance and persistent visceral inflammation resulted in visceral hyperalgesia. It has also been suggested that hyperexcitability of sensory neurons due to altered TTX-R Na+ channel properties and expression contributes to hyperalgesia; however, we do not know if some TTX-R Na+ channel property changes can be triggered by visceral hyperalgesia and morphine tolerance, or whether there are similar molecular or channel mechanisms in both situations. To evaluate the effects of morphine tolerance and visceral inflammation on the channel, we investigated the dorsal root ganglia (DRG neuronal change following these chronic treatments. Using whole-cell patch clamp recording, we recorded TTX-R Na+ currents in isolated adult rat lumbar and sacral (L6-S2 DRG neurons from normal and pathologic rats with colon inflammatory pain or chronic morphine treatment. We found that the amplitudes of TTX-R Na+ currents were signiflcantly increased in small-diameter DRG neurons with either morphine tolerance or visceral inflammatory pain. Meanwhile, the result also showed that those treatments altered the kinetics properties of the electrical current (ie, the activating and inactivating speed of the channel was accelerated. Our current results suggested that in both models, visceral chronic inflammatory pain and morphine tolerance causes electrophysiological changes in voltage

  7. Structure-activity relationships for the action of 11 pyrethroid insecticides on rat Nav1.8 sodium channels expressed in Xenopus oocytes

    International Nuclear Information System (INIS)

    Choi, J.-S.; Soderlund, David M.

    2006-01-01

    Pyrethroid insecticides bind to voltage-sensitive sodium channels and modify their gating kinetics, thereby disrupting nerve function. This paper describes the action of 11 structurally diverse commercial pyrethroid insecticides on the rat Na v 1.8 sodium channel isoform, the principal carrier of the tetrodotoxin-resistant, pyrethroid-sensitive sodium current of sensory neurons, expressed in Xenopus laevis oocytes. All 11 compounds produced characteristic sodium tail currents following a depolarizing pulse that ranged from rapidly-decaying monoexponential currents (allethrin, cismethrin and permethrin) to persistent biexponential currents (cyfluthrin, cyhalothrin, cypermethrin and deltamethrin). Tail currents for the remaining compounds (bifenthrin, fenpropathrin, fenvalerate and tefluthrin) were monoexponential and decayed with kinetics intermediate between these extremes. Reconstruction of currents carried solely by the pyrethroid-modified subpopulation of channels revealed two types of pyrethroid-modified currents. The first type, found with cismethrin, allethrin, permethrin and tefluthrin, activated relatively rapidly and inactivated partially during a 40-ms depolarization. The second type, found with cypermethrin, cyfluthrin, cyhalothrin, deltamethrin, fenpropathrin and fenvalerate, activated more slowly and did not detectably inactivate during a 40-ms depolarization. Only bifenthrin did not produce modified currents that fit clearly into either of these categories. In all cases, the rate of activation of modified channels was strongly correlated with the rate of tail current decay following repolarization. Modification of Na v 1.8 sodium channels by cyfluthrin, cyhalothrin, cypermethrin and deltamethrin was enhanced 2.3- to 3.4-fold by repetitive stimulation; this effect appeared to result from the accumulation of persistently open channels rather than preferential binding to open channel states. Fenpropathrin was the most effective compound against Na v 1

  8. Direct evidence that scorpion α-toxins (site-3 modulate sodium channel inactivation by hindrance of voltage-sensor movements.

    Directory of Open Access Journals (Sweden)

    Zhongming Ma

    Full Text Available The position of the voltage-sensing transmembrane segment, S4, in voltage-gated ion channels as a function of voltage remains incompletely elucidated. Site-3 toxins bind primarily to the extracellular loops connecting transmembrane helical segments S1-S2 and S3-S4 in Domain 4 (D4 and S5-S6 in Domain 1 (D1 and slow fast-inactivation of voltage-gated sodium channels. As S4 of the human skeletal muscle voltage-gated sodium channel, hNav1.4, moves in response to depolarization from the resting to the inactivated state, two D4S4 reporters (R2C and R3C, Arg1451Cys and Arg1454Cys, respectively move from internal to external positions as deduced by reactivity to internally or externally applied sulfhydryl group reagents, methane thiosulfonates (MTS. The changes in reporter reactivity, when cycling rapidly between hyperpolarized and depolarized voltages, enabled determination of the positions of the D4 voltage-sensor and of its rate of movement. Scorpion α-toxin binding impedes D4S4 segment movement during inactivation since the modification rates of R3C in hNav1.4 with methanethiosulfonate (CH3SO2SCH2CH2R, where R = -N(CH33 (+ trimethylammonium, MTSET and benzophenone-4-carboxamidocysteine methanethiosulfonate (BPMTS were slowed ~10-fold in toxin-modified channels. Based upon the different size, hydrophobicity and charge of the two reagents it is unlikely that the change in reactivity is due to direct or indirect blockage of access of this site to reagent in the presence of toxin (Tx, but rather is the result of inability of this segment to move outward to the normal extent and at the normal rate in the toxin-modified channel. Measurements of availability of R3C to internally applied reagent show decreased access (slower rates of thiol reaction providing further evidence for encumbered D4S4 movement in the presence of toxins consistent with the assignment of at least part of the toxin binding site to the region of D4S4 region of the voltage

  9. Distribution of TTX-sensitive voltage-gated sodium channels in primary sensory endings of mammalian muscle spindles.

    Science.gov (United States)

    Carrasco, Dario I; Vincent, Jacob A; Cope, Timothy C

    2017-04-01

    Knowledge of the molecular mechanisms underlying signaling of mechanical stimuli by muscle spindles remains incomplete. In particular, the ionic conductances that sustain tonic firing during static muscle stretch are unknown. We hypothesized that tonic firing by spindle afferents depends on sodium persistent inward current (INaP) and tested for the necessary presence of the appropriate voltage-gated sodium (NaV) channels in primary sensory endings. The NaV 1.6 isoform was selected for both its capacity to produce INaP and for its presence in other mechanosensors that fire tonically. The present study shows that NaV 1.6 immunoreactivity (IR) is concentrated in heminodes, presumably where tonic firing is generated, and we were surprised to find NaV 1.6 IR strongly expressed also in the sensory terminals, where mechanotransduction occurs. This spatial pattern of NaV 1.6 IR distribution was consistent for three mammalian species (rat, cat, and mouse), as was tonic firing by primary spindle afferents. These findings meet some of the conditions needed to establish participation of INaP in tonic firing by primary sensory endings. The study was extended to two additional NaV isoforms, selected for their sensitivity to TTX, excluding TTX-resistant NaV channels, which alone are insufficient to support firing by primary spindle endings. Positive immunoreactivity was found for NaV 1.1 , predominantly in sensory terminals together with NaV 1.6 and for NaV 1.7 , mainly in preterminal axons. Differential distribution in primary sensory endings suggests specialized roles for these three NaV isoforms in the process of mechanosensory signaling by muscle spindles. NEW & NOTEWORTHY The molecular mechanisms underlying mechanosensory signaling responsible for proprioceptive functions are not completely elucidated. This study provides the first evidence that voltage-gated sodium channels (NaVs) are expressed in the spindle primary sensory ending, where NaVs are found at every site

  10. Comparison and optimization of in silico algorithms for predicting the pathogenicity of sodium channel variants in epilepsy.

    Science.gov (United States)

    Holland, Katherine D; Bouley, Thomas M; Horn, Paul S

    2017-07-01

    Variants in neuronal voltage-gated sodium channel α-subunits genes SCN1A, SCN2A, and SCN8A are common in early onset epileptic encephalopathies and other autosomal dominant childhood epilepsy syndromes. However, in clinical practice, missense variants are often classified as variants of uncertain significance when missense variants are identified but heritability cannot be determined. Genetic testing reports often include results of computational tests to estimate pathogenicity and the frequency of that variant in population-based databases. The objective of this work was to enhance clinicians' understanding of results by (1) determining how effectively computational algorithms predict epileptogenicity of sodium channel (SCN) missense variants; (2) optimizing their predictive capabilities; and (3) determining if epilepsy-associated SCN variants are present in population-based databases. This will help clinicians better understand the results of indeterminate SCN test results in people with epilepsy. Pathogenic, likely pathogenic, and benign variants in SCNs were identified using databases of sodium channel variants. Benign variants were also identified from population-based databases. Eight algorithms commonly used to predict pathogenicity were compared. In addition, logistic regression was used to determine if a combination of algorithms could better predict pathogenicity. Based on American College of Medical Genetic Criteria, 440 variants were classified as pathogenic or likely pathogenic and 84 were classified as benign or likely benign. Twenty-eight variants previously associated with epilepsy were present in population-based gene databases. The output provided by most computational algorithms had a high sensitivity but low specificity with an accuracy of 0.52-0.77. Accuracy could be improved by adjusting the threshold for pathogenicity. Using this adjustment, the Mendelian Clinically Applicable Pathogenicity (M-CAP) algorithm had an accuracy of 0.90 and a

  11. Increased serum neuron specific enolase concentrations in patients with hyperglycemic cortical ischemic stroke

    NARCIS (Netherlands)

    Elting, JW; De Keyser, J; Sulter, G.

    1998-01-01

    A detrimental effect of hyperglycemia in ischemic brain has been demonstrated in laboratory experiments and it has been found that hyperglycemia in ischemic stroke is a predictor of poor outcome. We determined serum neuron specific enolase (NSE) concentrations in 41 consecutive patients with a

  12. Veratridine activates a silent sodium-channel in rat isolated aorta

    NARCIS (Netherlands)

    WERMELSKIRCHEN, D; WILFFERT, B; NEBEL, U; LEIDIG, A; WIRTH, A; Peters, Thies

    1992-01-01

    To investigate the existence of silent Na+ channels, isolated rat aorta was treated with veratridine (0.1 mM) and the resulting Ca2+ uptake was determined. After 30-min incubation the total tissue uptake of Ca2+ and Ca2+ uptake increased from 2.325 +/- 0.017 to 2.614 +/- 0.080 nmol/mg wet weight

  13. cAMP-dependent kinase does not modulate the Slack sodium-activated potassium channel.

    Science.gov (United States)

    Nuwer, Megan O; Picchione, Kelly E; Bhattacharjee, Arin

    2009-09-01

    The Slack gene encodes a Na(+)-activated K(+) channel and is expressed in many different types of neurons. Like the prokaryotic Ca(2+)-gated K(+) channel MthK, Slack contains two 'regulator of K(+) conductance' (RCK) domains within its carboxy terminal, domains likely involved in Na(+) binding and channel gating. It also contains multiple consensus protein kinase C (PKC) and protein kinase A (PKA) phosphorylation sites and although regulated by protein kinase C (PKC) phosphorylation, modulation by PKA has not been determined. To test if PKA directly regulates Slack, nystatin-perforated patch whole-cell currents were recorded from a human embryonic kidney (HEK-293) cell line stably expressing Slack. Bath application of forskolin, an adenylate cyclase activator, caused a rapid and complete inhibition of Slack currents however, the inactive homolog of forskolin, 1,9-dideoxyforskolin caused a similar effect. In contrast, bath application of 8-bromo-cAMP did not affect the amplitude nor the activation kinetics of Slack currents. In excised inside-out patch recordings, direct application of the PKA catalytic subunit to patches did not affect the open probability of Slack channels nor was open probability affected by direct application of protein phosphatase 2B. Preincubation of cells with the protein kinase A inhibitor KT5720 also did not change current density. Finally, mutating the consensus phosphorylation site located between RCK domain 1 and domain 2 from serine to glutamate did not affect current activation kinetics. We conclude that unlike PKC, phosphorylation by PKA does not acutely modulate the function and gating activation kinetics of Slack channels.

  14. Sodium Channel β2 Subunits Prevent Action Potential Propagation Failures at Axonal Branch Points.

    Science.gov (United States)

    Cho, In Ha; Panzera, Lauren C; Chin, Morven; Hoppa, Michael B

    2017-09-27

    Neurotransmitter release depends on voltage-gated Na + channels (Na v s) to propagate an action potential (AP) successfully from the axon hillock to a synaptic terminal. Unmyelinated sections of axon are very diverse structures encompassing branch points and numerous presynaptic terminals with undefined molecular partners of Na + channels. Using optical recordings of Ca 2+ and membrane voltage, we demonstrate here that Na + channel β2 subunits (Na v β2s) are required to prevent AP propagation failures across the axonal arborization of cultured rat hippocampal neurons (mixed male and female). When Na v β2 expression was reduced, we identified two specific phenotypes: (1) membrane excitability and AP-evoked Ca 2+ entry were impaired at synapses and (2) AP propagation was severely compromised with >40% of axonal branches no longer responding to AP-stimulation. We went on to show that a great deal of electrical signaling heterogeneity exists in AP waveforms across the axonal arborization independent of axon morphology. Therefore, Na v β2 is a critical regulator of axonal excitability and synaptic function in unmyelinated axons. SIGNIFICANCE STATEMENT Voltage-gated Ca 2+ channels are fulcrums of neurotransmission that convert electrical inputs into chemical outputs in the form of vesicle fusion at synaptic terminals. However, the role of the electrical signal, the presynaptic action potential (AP), in modulating synaptic transmission is less clear. What is the fidelity of a propagating AP waveform in the axon and what molecules shape it throughout the axonal arborization? Our work identifies several new features of AP propagation in unmyelinated axons: (1) branches of a single axonal arborization have variable AP waveforms independent of morphology, (2) Na + channel β2 subunits modulate AP-evoked Ca 2+ -influx, and (3) β2 subunits maintain successful AP propagation across the axonal arbor. These findings are relevant to understanding the flow of excitation in the

  15. High affinity for the rat brain sodium channel of newly discovered hydroxybenzoate saxitoxin analogues from the dinoflagellate Gymnodinium catenatum.

    Science.gov (United States)

    Llewellyn, Lyndon; Negri, Andrew; Quilliam, Michael

    2004-01-01

    The paralytic shellfish poison family has been recently extended by the discovery of several analogues possessing a hydoxybenzoate moiety instead of the carbamoyl group one finds in saxitoxin, the parent molecule of this toxin family. We have investigated the potency of these new analogues on a representative isoform of the pharmacological target of these toxins, the voltage gated sodium channel. These toxins were found to have K1's in the low nanomolar range, only slightly less potent than saxitoxin. The hydroxybenzoate group may increase the lipophilicity of these toxins and improve their ability to pass through epithelia and therefore its uptake and elimination in both intoxication victims and animals that bioaccumulate paralytic shellfish toxins.

  16. Pyrethroid resistance in Sitophilus zeamais is associated with a mutation (T929I) in the voltage-gated sodium channel.

    Science.gov (United States)

    Araújo, Rúbia A; Williamson, Martin S; Bass, Christopher; Field, Linda M; Duce, Ian R

    2011-08-01

    The maize weevil, Sitophilus zeamais, is the most important pest affecting stored grain in Brazil and its control relies heavily on the use of insecticides. The intensive use of compounds such as the pyrethroids has led to the emergence of resistance, and previous studies have suggested that resistance to both pyrethroids and 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) may result from reduced sensitivity of the insecticide target, the voltage-gated sodium channel. To identify the molecular mechanisms underlying pyrethroid resistance in S. zeamais, the domain II region of the voltage-gated sodium channel (para-orthologue) gene was amplified by PCR and sequenced from susceptible and resistant laboratory S. zeamais strains that were selected with a discriminating dose of DDT. A single point mutation, T929I, was found in the para gene of the resistant S. zeamais populations and its presence in individual weevils was strongly associated with survival after DDT exposure. This is the first identification of a target-site resistance mutation in S. zeamais and unusually it is a super-kdr type mutation occurring in the absence of the more common kdr (L1014F) substitution. A high-throughput assay based on TaqMan single nucleotide polymorphism genotyping was developed for sensitive detection of the mutation and used to screen field-collected strains of S. zeamais. This showed that the mutation is present at low frequency in field populations and is a useful tool for informing control strategies. © 2011 The Authors. Insect Molecular Biology © 2011 The Royal Entomological Society.

  17. Identification of Novel Voltage-Gated Sodium Channel Mutations in Human Head and Body Lice (Phthiraptera: Pediculidae).

    Science.gov (United States)

    Firooziyan, Samira; Sadaghianifar, Ali; Taghilou, Behrooz; Galavani, Hossein; Ghaffari, Eslam; Gholizadeh, Saber

    2017-09-01

    In recent years, the increase of head louse infestation in Iran (7.4%) and especially in West-Azerbaijan Province (248%) has raised the hypothesis of insecticide resistance development. There are different mechanisms of resistance to various groups of insecticides, and knockdown resistance (kdr) is a prominent mechanism of resistance to pyrethroids, an insecticide group which is used conventionally for pediculosis control. For detection of kdr-type well-known amino acid substitutions (M815I-T917I-L920F) and additional sodium channel mutations potentially associated with kdr resistance in head and body lice, louse populations were collected from West-Azerbaijan and Zanjan Provinces of Iran. Six novel mutations were found to be located in the IIS1-2 extracellular loop (H813P) and IIS5 (I927F, L928A, R929V, L930M, and L932M) of the α-subunit. Genotyping results showed that all specimens (100%) have at least one of these or the well-known mutations. Therefore, the presence of kdr-related and novel mutations in the sodium channel is likely to be the reason for the frequent use of pyrethroid insecticides due to treatment failure against lice. Further studies are now required to evaluate the prevalence of the kdr-like mutant allele for monitoring of insecticide resistance and the management of head and body lice in other provinces of the country. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  18. CNS sites activated by renal pelvic epithelial sodium channels (ENaCs) in response to hypertonic saline in awake rats.

    Science.gov (United States)

    Goodwill, Vanessa S; Terrill, Christopher; Hopewood, Ian; Loewy, Arthur D; Knuepfer, Mark M

    2017-05-01

    In some patients, renal nerve denervation has been reported to be an effective treatment for essential hypertension. Considerable evidence suggests that afferent renal nerves (ARN) and sodium balance play important roles in the development and maintenance of high blood pressure. ARN are sensitive to sodium concentrations in the renal pelvis. To better understand the role of ARN, we infused isotonic or hypertonic NaCl (308 or 500mOsm) into the left renal pelvis of conscious rats for two 2hours while recording arterial pressure and heart rate. Subsequently, brain tissue was analyzed for immunohistochemical detection of the protein Fos, a marker for neuronal activation. Fos-immunoreactive neurons were identified in numerous sites in the forebrain and brainstem. These areas included the nucleus tractus solitarius (NTS), the lateral parabrachial nucleus, the paraventricular nucleus of the hypothalamus (PVH) and the supraoptic nucleus (SON). The most effective stimulus was 500mOsm NaCl. Activation of these sites was attenuated or prevented by administration of benzamil (1μM) or amiloride (10μM) into the renal pelvis concomitantly with hypertonic saline. In anesthetized rats, infusion of hypertonic saline but not isotonic saline into the renal pelvis elevated ARN activity and this increase was attenuated by simultaneous infusion of benzamil or amiloride. We propose that renal pelvic epithelial sodium channels (ENaCs) play a role in activation of ARN and, via central visceral afferent circuits, this system modulates fluid volume and peripheral blood pressure. These pathways may contribute to the development of hypertension. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. THE PRESENCE OF A B SUBUNIT INCREASES SENSITIVITY OF SODIUM CHANNEL NAV1.3, BUT NOT NAV1.2, TO TYPE II PYRETHROIDS.

    Science.gov (United States)

    Voltage-sensitive sodium channels (VSSCs) are a primary target of pyrethroid insecticides. VSSCs are comprised of a pore-forming ¿ and auxillary ß subunits, and multiple isoforms of both subunit types exist. The sensitivity of different isoform combinations to pyrethroids has not...

  20. Spatiotemporal magnetic fields enhance cytosolic Ca.sup.2+./sup. levels and induce actin polymerization via activation of voltage-gated sodium channels in skeletal muscle cells

    Czech Academy of Sciences Publication Activity Database

    Rubio Ayala, M.; Syrovets, T.; Hafner, S.; Zablotskyy, Vitaliy A.; Dejneka, Alexandr; Simmet, T.

    2018-01-01

    Roč. 163, May (2018), s. 174-184 ISSN 0142-9612 Institutional support: RVO:68378271 Keywords : alternating magnetic field * skeletal muscle * cytosolic calcium * modeling * eddy current * voltage-gated sodium channels Subject RIV: BO - Biophysics OBOR OECD: Biophysics Impact factor: 8.402, year: 2016

  1. Increased renal alpha-epithelial sodium channel (ENAC) protein and increased ENAC activity in normal pregnancy.

    Science.gov (United States)

    West, Crystal; Zhang, Zheng; Ecker, Geoffrey; Masilamani, Shyama M E

    2010-11-01

    Pregnancy-mediated sodium (Na) retention is required to provide an increase in plasma volume for the growing fetus. The mechanisms responsible for this Na retention are not clear. We first used a targeted proteomics approach and found that there were no changes in the protein abundance compared with virgin rats of the β or γ ENaC, type 3 Na(+)/H(+) exchanger (NHE3), bumetanide-sensitive cotransporter (NKCC2), or NaCl cotransporter (NCC) in mid- or late pregnancy. In contrast, we observed marked increases in the abundance of the α-ENaC subunit. The plasma volume increased progressively during pregnancy with the greatest plasma volume being evident in late pregnancy. ENaC inhibition abolished the difference in plasma volume status between virgin and pregnant rats. To determine the in vivo activity of ENaC, we conducted in vivo studies of rats in late pregnancy (days 18-20) and virgin rats to measure the natriuretic response to ENaC blockade (with benzamil). The in vivo activity of ENaC (U(Na)V postbenzamil-U(Na)V postvehicle) was markedly increased in late pregnancy, and this difference was abolished by pretreatment with the mineralocorticoid receptor antagonist, eplerenone. These findings demonstrate that the increased α-ENaC subunit of pregnancy is associated with an mineralocorticoid-dependent increase in ENaC activity. Further, we show that ENaC activity is a major contributor of plasma volume status in late pregnancy. These changes are likely to contribute to the renal sodium retention and plasma volume expansion required for an optimal pregnancy.

  2. Functional suppression of Kcnq1 leads to early sodium channel remodelling and cardiac conduction system dysmorphogenesis

    Czech Academy of Sciences Publication Activity Database

    De la Rosa, A. J.; Domínguez, J. N.; Sedmera, D.; Šaňková, Barbora; Hove-Madsen, L.; Franco, D.; Aránega, A. E.

    2013-01-01

    Roč. 98, č. 3 (2013), s. 504-514 ISSN 0008-6363 R&D Projects: GA ČR(CZ) GA304/08/0615; GA ČR(CZ) GAP302/11/1308; GA ČR(CZ) GD204/09/H084; GA ČR(CZ) GA13-12412S Institutional research plan: CEZ:AV0Z50110509 Institutional support: RVO:67985823 Keywords : ion channels * Long-QT syndrome * sudden death * cardiac hypertrophy Subject RIV: FA - Cardiovascular Diseases incl. Cardiotharic Surgery Impact factor: 5.808, year: 2013

  3. Individual variation and hormonal modulation of a sodium channel beta subunit in the electric organ correlate with variation in a social signal.

    Science.gov (United States)

    Liu, He; Wu, Ming-Ming; Zakon, Harold H

    2007-09-01

    The sodium channel beta1 subunit affects sodium channel gating and surface density, but little is known about the factors that regulate beta1 expression or its participation in the fine control of cellular excitability. In this study we examined whether graded expression of the beta1 subunit contributes to the gradient in sodium current inactivation, which is tightly controlled and directly related to a social behavior, the electric organ discharge (EOD), in a weakly electric fish Sternopygus macrurus. We found the mRNA and protein levels of beta1 in the electric organ both correlate with EOD frequency. We identified a novel mRNA splice form of this gene and found the splicing preference for this novel splice form also correlates with EOD frequency. Androgen implants lowered EOD frequency and decreased the beta1 mRNA level but did not affect splicing. Coexpression of each splice form in Xenopus oocytes with either the human muscle sodium channel gene, hNav1.4, or a Sternopygus ortholog, smNav1.4b, sped the rate of inactivation of the sodium current and shifted the steady-state inactivation toward less negative membrane potentials. The translational product of the novel mRNA splice form lacks a previously identified important tyrosine residue but still functions normally. The properties of the fish alpha and coexpressed beta1 subunits in the oocyte replicate those of the electric organ's endogenous sodium current. These data highlight the role of ion channel beta subunits in regulating cellular excitability.

  4. Correlative study between neuron-specific enolase and blood sugar level in ischemic stroke patients

    OpenAIRE

    Pandey, Aparna; Saxena, Kiran; Verma, Meena; Bharosay, Anuradha

    2011-01-01

    Background: A study to investigate the level of the neurobiochemical marker, Neuron-Specific Enolase (NSE), at the time of admission and its correlation with the blood sugar level in ischemic stroke patients. Patients and Methods: We investigated 90 patients with complete stroke who were admitted to the Stroke Unit of the Department of Neurology at Sri Aurobindo Institute of Medical Sciences. NSE was measured with commercially available quantitative ′sandwich′ enzyme-linked immunosorbent assa...

  5. Molecular modelling studies of kdr mutations in voltage gated sodium channel revealed significant conformational variations contributing to insecticide resistance.

    Science.gov (United States)

    Yellapu, Nanda Kumar; Gopal, Jeyakodi; Kasinathan, Gunasekaran; Purushothaman, Jambulingam

    2018-06-01

    Voltage gated sodium channels (VGSC) of mosquito vectors are the primary targets of dichlorodiphenyltrichloroethane (DDT) and other synthetic pyrethroids used in public health programmes. The knockdown resistant (kdr) mutations in VGSC are associated with the insecticide resistance especially in Anophelines. The present study is aimed to emphasize and demarcate the impact of three kdr-mutations such as L1014S, L1014F and L1014H on insecticide resistance. The membrane model of sodium transport domain of VGSC (STD-VGSC) was constructed using de novo approach based on domain and trans-membrane predictions. The comparative molecular modelling studies of wild type and mutant models of STD-VGSC revealed that L1014F mutant was observed to be near native to the wild type model in all the respects, but, L1014S and L1014H mutations showed drastic variations in the energy levels, root mean square fluctuations (RMSF) that resulted in conformational variations. The predicted binding sites also showed variable cavity volumes and RMSF in L1014S and L1014H mutants. Further, DDT also found be bound in near native manner to wild type in L1014F mutant and with variable orientation and affinities in L1014S and L1014H mutants. The variations and fluctuations observed in mutant structures explained that each mutation has its specific impact on the conformation of VGSC and its binding with DDT. The study provides new insights into the structure-function-correlations of mutant STD-VGSC structures and demonstrates the role and effects of kdr mutations on insecticide resistance in mosquito vectors.

  6. Effects of Amiodarone and N-Desethylamiodarone on Cardiac Voltage-gated Sodium Channels

    Directory of Open Access Journals (Sweden)

    Mohammad-Reza eGhovanloo

    2016-03-01

    Full Text Available Amiodarone (AMD is a potent antiarrhythmic drug with high efficacy for treating atrial fibrillation and tachycardia. The pharmacologic profile of AMD is complex. AMD possesses biophysical characteristics of all of class I, II, III, and IV agents. Despite its adverse side effects, AMD remains the most commonly prescribed antiarrhythmic drug. AMD was described to prolong the QT interval and can lead to torsades de pointes. Our goal was to study the effects of AMD on peak and late sodium currents (INa,P and INa,L and determine whether these effects change as AMD is metabolized into N-Desethylamiodarone (DES. We hypothesized that AMD and DES block both INa,P and INa,L with similar profiles due to structural similarities. Given the inherent small amounts of INa,L in NaV1.5, we screened AMD and DES against the Long QT-3-causing mutation, ∆KPQ, to better detect any drug-mediated effect on INa,L. Our results show that AMD and DES do not affect WT or ∆KPQ activation; however, both drugs altered the apparent valence of steady-state fast-inactivation. In addition, AMD and DES preferentially block ∆KPQ peak conductance compared to WT. Both compounds significantly increase INa,L and window currents. We conclude that both compounds have pro-arrhythmic effects on NaV1.5, especially ∆KPQ; however, DES seems to have a greater pro-arrhythmic effect than AMD.

  7. Modular organization of α-toxins from scorpion venom mirrors domain structure of their targets, sodium channels.

    Science.gov (United States)

    Chugunov, Anton O; Koromyslova, Anna D; Berkut, Antonina A; Peigneur, Steve; Tytgat, Jan; Polyansky, Anton A; Pentkovsky, Vladimir M; Vassilevski, Alexander A; Grishin, Eugene V; Efremov, Roman G

    2013-06-28

    To gain success in the evolutionary "arms race," venomous animals such as scorpions produce diverse neurotoxins selected to hit targets in the nervous system of prey. Scorpion α-toxins affect insect and/or mammalian voltage-gated sodium channels (Na(v)s) and thereby modify the excitability of muscle and nerve cells. Although more than 100 α-toxins are known and a number of them have been studied into detail, the molecular mechanism of their interaction with Na(v)s is still poorly understood. Here, we employ extensive molecular dynamics simulations and spatial mapping of hydrophobic/hydrophilic properties distributed over the molecular surface of α-toxins. It is revealed that despite the small size and relatively rigid structure, these toxins possess modular organization from structural, functional, and evolutionary perspectives. The more conserved and rigid "core module" is supplemented with the "specificity module" (SM) that is comparatively flexible and variable and determines the taxon (mammal versus insect) specificity of α-toxin activity. We further show that SMs in mammal toxins are more flexible and hydrophilic than in insect toxins. Concomitant sequence-based analysis of the extracellular loops of Na(v)s suggests that α-toxins recognize the channels using both modules. We propose that the core module binds to the voltage-sensing domain IV, whereas the more versatile SM interacts with the pore domain in repeat I of Na(v)s. These findings corroborate and expand the hypothesis on different functional epitopes of toxins that has been reported previously. In effect, we propose that the modular structure in toxins evolved to match the domain architecture of Na(v)s.

  8. On the Mechanism of Human Red Blood Cell Longevity: Roles of Calcium, the Sodium Pump, PIEZO1, and Gardos Channels

    Directory of Open Access Journals (Sweden)

    Virgilio L. Lew

    2017-12-01

    Full Text Available In a healthy adult, the transport of O2 and CO2 between lungs and tissues is performed by about 2 · 1013 red blood cells, of which around 1.7 · 1011 are renewed every day, a turnover resulting from an average circulatory lifespan of about 120 days. Cellular lifespan is the result of an evolutionary balance between the energy costs of maintaining cells in a fit functional state versus cell renewal. In this Review we examine how the set of passive and active membrane transporters of the mature red blood cells interact to maximize their circulatory longevity thus minimizing costs on expensive cell turnover. Red blood cell deformability is critical for optimal rheology and gas exchange functionality during capillary flow, best fulfilled when the volume of each human red blood cell is kept at a fraction of about 0.55–0.60 of the maximal spherical volume allowed by its membrane area, the optimal-volume-ratio range. The extent to which red blood cell volumes can be preserved within or near these narrow optimal-volume-ratio margins determines the potential for circulatory longevity. We show that the low cation permeability of red blood cells allows volume stability to be achieved with extraordinary cost-efficiency, favouring cell longevity over cell turnover. We suggest a mechanism by which the interplay of a declining sodium pump and two passive membrane transporters, the mechanosensitive PIEZO1 channel, a candidate mediator of Psickle in sickle cells, and the Ca2+-sensitive, K+-selective Gardos channel, can implement red blood cell volume stability around the optimal-volume-ratio range, as required for extended circulatory longevity.

  9. The Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) voltage-gated sodium channel and mutations associated with pyrethroid resistance in field-collected adult males.

    Science.gov (United States)

    Hopkins, B W; Pietrantonio, P V

    2010-05-01

    Helicoverpa zea is one of the most costly insect pests of food and fiber crops throughout the Americas. Pyrethroid insecticides are widely applied for its control as they are effective and relatively inexpensive; however, resistance to pyrethroids threatens agricultural systems sustainability because alternative insecticides are often more expensive or less effective. Although pyrethroid resistance has been identified in this pest since 1990, the mechanisms of resistance have not yet been elucidated at the molecular level. Pyrethroids exert their toxicity by prolonging the open state of the voltage-gated sodium channel. Here we report the cDNA sequence of the H. zea sodium channel alpha-subunit homologous to the para gene from Drosophila melanogaster. In field-collected males which were resistant to cypermethrin as determined by the adult vial test, we identify known resistance-conferring mutations L1029H and V421M, along with two novel mutations at the V421 residue, V421A and V421G. An additional mutation, I951V, may be the first example of a pyrethroid resistance mutation caused by RNA editing. Identification of the sodium channel cDNA sequence will allow for testing hypotheses on target-site resistance for insecticides acting on this channel through modeling and expression studies. Understanding the mechanisms responsible for resistance will greatly improve our ability to identify and predict resistance, as well as preserve susceptibility to pyrethroid insecticides. Copyright 2010 Elsevier Ltd. All rights reserved.

  10. Voltage-gated sodium channel polymorphism and metabolic resistance in pyrethroid-resistant Aedes aegypti from Brazil.

    Science.gov (United States)

    Martins, Ademir Jesus; Lins, Rachel Mazzei Moura de Andrade; Linss, Jutta Gerlinde Birgitt; Peixoto, Alexandre Afranio; Valle, Denise

    2009-07-01

    The nature of pyrethroid resistance in Aedes aegypti Brazilian populations was investigated. Quantification of enzymes related to metabolic resistance in two distinct populations, located in the Northeast and Southeast regions, revealed increases in Glutathione-S-transferase (GST) and Esterase levels. Additionally, polymorphism was found in the IIS6 region of Ae. aegypti voltage-gated sodium channel (AaNa(V)), the pyrethroid target site. Sequences were classified in two haplotype groups, A and B, according to the size of the intron in that region. Rockefeller, a susceptible control lineage, contains only B sequences. In field populations, some A sequences present a substitution in the 1011 site (Ile/Met). When resistant and susceptible individuals were compared, the frequency of both A (with the Met mutation) and B sequences were slightly increased in resistant specimens. The involvement of the AaNa(V) polymorphism in pyrethroid resistance and the metabolic mechanisms that lead to potential cross-resistance between organophosphate and pyrethroids are discussed.

  11. Novel Mutations in the Voltage-Gated Sodium Channel of Pyrethroid-Resistant Varroa destructor Populations from the Southeastern USA.

    Science.gov (United States)

    González-Cabrera, Joel; Rodríguez-Vargas, Sonia; Davies, T G Emyr; Field, Linda M; Schmehl, Daniel; Ellis, James D; Krieger, Klemens; Williamson, Martin S

    2016-01-01

    The parasitic mite Varroa destructor has a significant worldwide impact on bee colony health. In the absence of control measures, parasitized colonies invariably collapse within 3 years. The synthetic pyrethroids tau-fluvalinate and flumethrin have proven very effective at managing this mite within apiaries, but intensive control programs based mainly on one active ingredient have led to many reports of pyrethroid resistance. In Europe, a modification of leucine to valine at position 925 (L925V) of the V. destructor voltage-gated sodium channel was correlated with resistance, the mutation being found at high frequency exclusively in hives with a recent history of pyrethroid treatment. Here, we identify two novel mutations, L925M and L925I, in tau-fluvalinate resistant V. destructor collected at seven sites across Florida and Georgia in the Southeastern region of the USA. Using a multiplexed TaqMan® allelic discrimination assay, these mutations were found to be present in 98% of the mites surviving tau-fluvalinate treatment. The mutations were also found in 45% of the non-treated mites, suggesting a high potential for resistance evolution if selection pressure is applied. The results from a more extensive monitoring programme, using the Taqman® assay described here, would clearly help beekeepers with their decision making as to when to include or exclude pyrethroid control products and thereby facilitate more effective mite management programmes.

  12. Novel Mutations in the Voltage-Gated Sodium Channel of Pyrethroid-Resistant Varroa destructor Populations from the Southeastern USA.

    Directory of Open Access Journals (Sweden)

    Joel González-Cabrera

    Full Text Available The parasitic mite Varroa destructor has a significant worldwide impact on bee colony health. In the absence of control measures, parasitized colonies invariably collapse within 3 years. The synthetic pyrethroids tau-fluvalinate and flumethrin have proven very effective at managing this mite within apiaries, but intensive control programs based mainly on one active ingredient have led to many reports of pyrethroid resistance. In Europe, a modification of leucine to valine at position 925 (L925V of the V. destructor voltage-gated sodium channel was correlated with resistance, the mutation being found at high frequency exclusively in hives with a recent history of pyrethroid treatment. Here, we identify two novel mutations, L925M and L925I, in tau-fluvalinate resistant V. destructor collected at seven sites across Florida and Georgia in the Southeastern region of the USA. Using a multiplexed TaqMan® allelic discrimination assay, these mutations were found to be present in 98% of the mites surviving tau-fluvalinate treatment. The mutations were also found in 45% of the non-treated mites, suggesting a high potential for resistance evolution if selection pressure is applied. The results from a more extensive monitoring programme, using the Taqman® assay described here, would clearly help beekeepers with their decision making as to when to include or exclude pyrethroid control products and thereby facilitate more effective mite management programmes.

  13. Novel Mutations in the Voltage-Gated Sodium Channel of Pyrethroid-Resistant Varroa destructor Populations from the Southeastern USA

    Science.gov (United States)

    González-Cabrera, Joel; Rodríguez-Vargas, Sonia; Davies, T. G. Emyr; Field, Linda M.; Schmehl, Daniel; Ellis, James D.; Krieger, Klemens; Williamson, Martin S.

    2016-01-01

    The parasitic mite Varroa destructor has a significant worldwide impact on bee colony health. In the absence of control measures, parasitized colonies invariably collapse within 3 years. The synthetic pyrethroids tau-fluvalinate and flumethrin have proven very effective at managing this mite within apiaries, but intensive control programs based mainly on one active ingredient have led to many reports of pyrethroid resistance. In Europe, a modification of leucine to valine at position 925 (L925V) of the V. destructor voltage-gated sodium channel was correlated with resistance, the mutation being found at high frequency exclusively in hives with a recent history of pyrethroid treatment. Here, we identify two novel mutations, L925M and L925I, in tau-fluvalinate resistant V. destructor collected at seven sites across Florida and Georgia in the Southeastern region of the USA. Using a multiplexed TaqMan® allelic discrimination assay, these mutations were found to be present in 98% of the mites surviving tau-fluvalinate treatment. The mutations were also found in 45% of the non-treated mites, suggesting a high potential for resistance evolution if selection pressure is applied. The results from a more extensive monitoring programme, using the Taqman® assay described here, would clearly help beekeepers with their decision making as to when to include or exclude pyrethroid control products and thereby facilitate more effective mite management programmes. PMID:27191597

  14. Transcranial Random Noise Stimulation-induced plasticity is NMDA-receptor independent but sodium-channel blocker and benzodiazepines sensitive

    Directory of Open Access Journals (Sweden)

    Leila eChaieb

    2015-04-01

    Full Text Available Background: Application of transcranial random noise stimulation (tRNS between 0.1 and 640 Hz of the primary motor cortex (M1 for 10 minutes induces a persistent excitability increase lasting for at least 60 minutes. However, the mechanism of tRNS-induced cortical excitability alterations is not yet fully understood. Objective: The main aim of this study was to get first efficacy data with regard to the possible neuronal effect of tRNS. Methods: Single-pulse transcranial magnetic stimulation (TMS was used to measure levels of cortical excitability before and after combined application of tRNS at an intensity of 1mA for 10mins stimulation duration and a pharmacological agent (or sham on 8 healthy male participants. Results: The sodium channel blocker carbamazepine showed a tendency towards inhibiting MEPs 5-60 mins poststimulation. The GABAA agonist lorazepam suppressed tRNS-induced cortical excitability increases at 0-20 and 60 min time points. The partial NMDA receptor agonist D-cycloserine, the NMDA receptor antagonist dextromethorphan and the D2/D3 receptor agonist ropinirole had no significant effects on the excitability increases seen with tRNS.Conclusions: In contrast to transcranial direct current stimulation (tDCS, aftereffects of tRNS are seem to be not NMDA receptor dependent and can be suppressed by benzodiazepines suggesting that tDCS and tRNS depend upon different mechanisms.

  15. Studies on the interaction between marine polyether toxins and the voltage sensitive sodium channel

    International Nuclear Information System (INIS)

    Tachibana, Kazuo; Konoki, Keichi; Fukuzawa, Seketsu

    2003-01-01

    An analysis was made on three-dimensional structure of membrane proteins by prolonging the activated state of membrane protein using external factors like natural toxins having a strong affinity to the activated state. In addition, this study aimed to clarify the structural basis for the activation of membrane proteins. First, functional analysis was made for the complex of potential-dependent Na channel and brevetoxin, marine polycyclic toxin. Then, its binding site was determined using photo-affinity labeling. Next, an investigation was made on intracellular target molecule of ritteragine B, a cytotoxic steroidal alkaloid isolated from Retterella tokioka Kott in 1992. This molecule was used to elucidate the mechanism of cell growth. It was suggested that the cytotoxity of ritteragine was not due to non-specific interaction with cell membrane, but due to an inhibition of some physiological activity through interaction with its target molecule. Furthermore, functional mechanism of norzoanthamine, a marine anti-osteoporosis alkaloid isolated from Zoanthus sp. was investigated using ovariectomized mouse as a postomenopausal osteoporosis model. It was demonstrated that the marine alkaloid is strongly inhibitory to lowering of bone weight and strength. To elucidate the physiological effects of zoanthamine in molecular level, construction of in vitro experimental system was made using human epithelial osteoblast, Saos-2, in which production of TGF-β has been demonstrated. When added with norzoanthamine to the model system, stimulative effects on its cell growth and adhesion were observed, indicating the expression of its target molecule. Additionally, functional analysis was made on okadaic acid binding protein, OABP-2. It has been reported that okadaic acid, a marine polyether toxin isolated from Halichondria okadai was strongly cytotoxic because of protein phosphatase activity. Since okadaic acid has been demonstrated to be also toxic to the host, sponge, it has been

  16. Coupled-channel optical calculation of electron-atom scattering: elastic scattering from sodium at 20 to 150 eV

    International Nuclear Information System (INIS)

    Bray, Igor; Konovalov, D.A.; McCarthy, I.E.

    1991-04-01

    A coupled-channel optical method for electron-atom scattering is applied to elastic electron-sodium scattering at energies of 20, 22.1, 54.4, 100, and 150 eV. It is demonstrated that the effect of all the inelastic channels on elastic scattering may be well reproduced by the 'ab initio' calculated complex non-local polarization potential. Whilst the experiments generally agree at small angles and therefore agree on the total elastic cross section, there is considerable discrepancy at intermediate and backward angles. 9 refs., 2 tabs., 1 fig

  17. Determining the Advantages, Costs, and Trade-Offs of a Novel Sodium Channel Mutation in the Copepod Acartia hudsonica to Paralytic Shellfish Toxins (PST.

    Directory of Open Access Journals (Sweden)

    Michael Finiguerra

    Full Text Available The marine copepod Acartia hudsonica was shown to be adapted to dinoflagellate prey, Alexandrium fundyense, which produce paralytic shellfish toxins (PST. Adaptation to PSTs in other organisms is caused by a mutation in the sodium channel. Recently, a mutation in the sodium channel in A. hudsonica was found. In this study, we rigorously tested for advantages, costs, and trade-offs associated with the mutant isoform of A. hudsonica under toxic and non-toxic conditions. We combined fitness with wild-type: mutant isoform ratio measurements on the same individual copepod to test our hypotheses. All A. hudsonica copepods express both the wild-type and mutant sodium channel isoforms, but in different proportions; some individuals express predominantly mutant (PMI or wild-type isoforms (PWI, while most individuals express relatively equal amounts of each (EI. There was no consistent pattern of improved performance as a function of toxin dose for egg production rate (EPR, ingestion rate (I, and gross growth efficiency (GGE for individuals in the PMI group relative to individuals in the PWI expression group. Neither was there any evidence to indicate a fitness benefit to the mutant isoform at intermediate toxin doses. No clear advantage under toxic conditions was associated with the mutation. Using a mixed-diet approach, there was also no observed relationship between individual wild-type: mutant isoform ratios and among expression groups, on both toxic and non-toxic diets, for eggs produced over three days. Lastly, expression of the mutant isoform did not mitigate the negative effects of the toxin. That is, the reductions in EPR from a toxic to non-toxic diet for copepods were independent of expression groups. Overall, the results did not support our hypotheses; the mutant sodium channel isoform does not appear to be related to adaptation to PST in A. hudsonica. Other potential mechanisms responsible for the adaptation are discussed.

  18. Evidence for Dual Binding Sites for 1,1,1-Trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) in Insect Sodium Channels.

    Science.gov (United States)

    Du, Yuzhe; Nomura, Yoshiko; Zhorov, Boris S; Dong, Ke

    2016-02-26

    1,1,1-Trichloro-2,2-bis(p-chlorophenyl)ethane (DDT), the first organochlorine insecticide, and pyrethroid insecticides are sodium channel agonists. Although the use of DDT is banned in most of the world due to its detrimental impact on the ecosystem, indoor residual spraying of DDT is still recommended for malaria control in Africa. Development of resistance to DDT and pyrethroids is a serious global obstacle for managing disease vectors. Mapping DDT binding sites is necessary for understanding mechanisms of resistance and modulation of sodium channels by structurally different ligands. The pioneering model of the housefly sodium channel visualized the first receptor for pyrethroids, PyR1, in the II/III domain interface and suggested that DDT binds within PyR1. Previously, we proposed the second pyrethroid receptor, PyR2, at the I/II domain interface. However, whether DDT binds to both pyrethroid receptor sites remains unknown. Here, using computational docking of DDT into the Kv1.2-based mosquito sodium channel model, we predict that two DDT molecules can bind simultaneously within PyR1 and PyR2. The bulky trichloromethyl group of each DDT molecule fits snugly between four helices in the bent domain interface, whereas two p-chlorophenyl rings extend into two wings of the interface. Model-driven mutagenesis and electrophysiological analysis confirmed these propositions and revealed 10 previously unknown DDT-sensing residues within PyR1 and PyR2. Our study proposes a dual DDT-receptor model and provides a structural background for rational development of new insecticides. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  19. Evidence for Dual Binding Sites for 1,1,1-Trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) in Insect Sodium Channels*

    Science.gov (United States)

    Du, Yuzhe; Nomura, Yoshiko; Zhorov, Boris S.; Dong, Ke

    2016-01-01

    1,1,1-Trichloro-2,2-bis(p-chlorophenyl)ethane (DDT), the first organochlorine insecticide, and pyrethroid insecticides are sodium channel agonists. Although the use of DDT is banned in most of the world due to its detrimental impact on the ecosystem, indoor residual spraying of DDT is still recommended for malaria control in Africa. Development of resistance to DDT and pyrethroids is a serious global obstacle for managing disease vectors. Mapping DDT binding sites is necessary for understanding mechanisms of resistance and modulation of sodium channels by structurally different ligands. The pioneering model of the housefly sodium channel visualized the first receptor for pyrethroids, PyR1, in the II/III domain interface and suggested that DDT binds within PyR1. Previously, we proposed the second pyrethroid receptor, PyR2, at the I/II domain interface. However, whether DDT binds to both pyrethroid receptor sites remains unknown. Here, using computational docking of DDT into the Kv1.2-based mosquito sodium channel model, we predict that two DDT molecules can bind simultaneously within PyR1 and PyR2. The bulky trichloromethyl group of each DDT molecule fits snugly between four helices in the bent domain interface, whereas two p-chlorophenyl rings extend into two wings of the interface. Model-driven mutagenesis and electrophysiological analysis confirmed these propositions and revealed 10 previously unknown DDT-sensing residues within PyR1 and PyR2. Our study proposes a dual DDT-receptor model and provides a structural background for rational development of new insecticides. PMID:26637352

  20. Immunoreactive neuron-specific enolase (NSE) is expressed in testicular carcinoma-in-situ

    DEFF Research Database (Denmark)

    Kang, J L; Rajpert-De Meyts, E; Skakkebaek, N E

    1996-01-01

    Neuron-specific enolase (NSE) is a well-known marker of tumours that have neuroendocrine origin. High levels of NSE have also been described in various types of testicular germ cell neoplasms, particularly in seminomas. To evaluate the presence of NSE in testicular carcinoma-in situ (CIS), a prei...... are evidence against a relationship between NSE and N-myc in testicular germ cell tumours. The high expression of NSE in CIS and overt germ cell tumours may be due to the increased gene dosage effect associated with the overrepresentation of isochromosome 12p....

  1. Molecular Surface of JZTX-V (β-Theraphotoxin-Cj2a Interacting with Voltage-Gated Sodium Channel Subtype NaV1.4

    Directory of Open Access Journals (Sweden)

    Ji Luo

    2014-07-01

    Full Text Available Voltage-gated sodium channels (VGSCs; NaV1.1–NaV1.9 have been proven to be critical in controlling the function of excitable cells, and human genetic evidence shows that aberrant function of these channels causes channelopathies, including epilepsy, arrhythmia, paralytic myotonia, and pain. The effects of peptide toxins, especially those isolated from spider venom, have shed light on the structure–function relationship of these channels. However, most of these toxins have not been analyzed in detail. In particular, the bioactive faces of these toxins have not been determined. Jingzhaotoxin (JZTX-V (also known as β-theraphotoxin-Cj2a is a 29-amino acid peptide toxin isolated from the venom of the spider Chilobrachys jingzhao. JZTX-V adopts an inhibitory cysteine knot (ICK motif and has an inhibitory effect on voltage-gated sodium and potassium channels. Previous experiments have shown that JZTX-V has an inhibitory effect on TTX-S and TTX-R sodium currents on rat DRG cells with IC50 values of 27.6 and 30.2 nM, respectively, and is able to shift the activation and inactivation curves to the depolarizing and the hyperpolarizing direction, respectively. Here, we show that JZTX-V has a much stronger inhibitory effect on NaV1.4, the isoform of voltage-gated sodium channels predominantly expressed in skeletal muscle cells, with an IC50 value of 5.12 nM, compared with IC50 values of 61.7–2700 nM for other heterologously expressed NaV1 subtypes. Furthermore, we investigated the bioactive surface of JZTX-V by alanine-scanning the effect of toxin on NaV1.4 and demonstrate that the bioactive face of JZTX-V is composed of three hydrophobic (W5, M6, and W7 and two cationic (R20 and K22 residues. Our results establish that, consistent with previous assumptions, JZTX-V is a Janus-faced toxin which may be a useful tool for the further investigation of the structure and function of sodium channels.

  2. Bromodomain-containing Protein 4 Activates Voltage-gated Sodium Channel 1.7 Transcription in Dorsal Root Ganglia Neurons to Mediate Thermal Hyperalgesia in Rats.

    Science.gov (United States)

    Hsieh, Ming-Chun; Ho, Yu-Cheng; Lai, Cheng-Yuan; Wang, Hsueh-Hsiao; Lee, An-Sheng; Cheng, Jen-Kun; Chau, Yat-Pang; Peng, Hsien-Yu

    2017-11-01

    Bromodomain-containing protein 4 binds acetylated promoter histones and promotes transcription; however, the role of bromodomain-containing protein 4 in inflammatory hyperalgesia remains unclear. Male Sprague-Dawley rats received hind paw injections of complete Freund's adjuvant to induce hyperalgesia. The dorsal root ganglia were examined to detect changes in bromodomain-containing protein 4 expression and the activation of genes involved in the expression of voltage-gated sodium channel 1.7, which is a key pain-related ion channel. The intraplantar complete Freund's adjuvant injections resulted in thermal hyperalgesia (4.0 ± 1.5 s; n = 7). The immunohistochemistry and immunoblotting results demonstrated an increase in the bromodomain-containing protein 4-expressing dorsal root ganglia neurons (3.78 ± 0.38 fold; n = 7) and bromodomain-containing protein 4 protein levels (2.62 ± 0.39 fold; n = 6). After the complete Freund's adjuvant injection, histone H3 protein acetylation was enhanced in the voltage-gated sodium channel 1.7 promoter, and cyclin-dependent kinase 9 and phosphorylation of RNA polymerase II were recruited to this area. Furthermore, the voltage-gated sodium channel 1.7-mediated currents were enhanced in neurons of the complete Freund's adjuvant rats (55 ± 11 vs. 19 ± 9 pA/pF; n = 4 to 6 neurons). Using bromodomain-containing protein 4-targeted antisense small interfering RNA to the complete Freund's adjuvant-treated rats, the authors demonstrated a reduction in the expression of bromodomain-containing protein 4 (0.68 ± 0.16 fold; n = 7), a reduction in thermal hyperalgesia (7.5 ± 1.5 s; n = 7), and a reduction in the increased voltage-gated sodium channel 1.7 currents (21 ± 4 pA/pF; n = 4 to 6 neurons). Complete Freund's adjuvant triggers enhanced bromodomain-containing protein 4 expression, ultimately leading to the enhanced excitability of nociceptive neurons and thermal hyperalgesia. This effect is

  3. Substitutions in the domain III voltage-sensing module enhance the sensitivity of an insect sodium channel to a scorpion beta-toxin.

    Science.gov (United States)

    Song, Weizhong; Du, Yuzhe; Liu, Zhiqi; Luo, Ningguang; Turkov, Michael; Gordon, Dalia; Gurevitz, Michael; Goldin, Alan L; Dong, Ke

    2011-05-06

    Scorpion β-toxins bind to the extracellular regions of the voltage-sensing module of domain II and to the pore module of domain III in voltage-gated sodium channels and enhance channel activation by trapping and stabilizing the voltage sensor of domain II in its activated state. We investigated the interaction of a highly potent insect-selective scorpion depressant β-toxin, Lqh-dprIT(3), from Leiurus quinquestriatus hebraeus with insect sodium channels from Blattella germanica (BgNa(v)). Like other scorpion β-toxins, Lqh-dprIT(3) shifts the voltage dependence of activation of BgNa(v) channels expressed in Xenopus oocytes to more negative membrane potentials but only after strong depolarizing prepulses. Notably, among 10 BgNa(v) splice variants tested for their sensitivity to the toxin, only BgNa(v)1-1 was hypersensitive due to an L1285P substitution in IIIS1 resulting from a U-to-C RNA-editing event. Furthermore, charge reversal of a negatively charged residue (E1290K) at the extracellular end of IIIS1 and the two innermost positively charged residues (R4E and R5E) in IIIS4 also increased the channel sensitivity to Lqh-dprIT(3). Besides enhancement of toxin sensitivity, the R4E substitution caused an additional 20-mV negative shift in the voltage dependence of activation of toxin-modified channels, inducing a unique toxin-modified state. Our findings provide the first direct evidence for the involvement of the domain III voltage-sensing module in the action of scorpion β-toxins. This hypersensitivity most likely reflects an increase in IIS4 trapping via allosteric mechanisms, suggesting coupling between the voltage sensors in neighboring domains during channel activation.

  4. Mutation in the Sodium Channel Gene Corresponds With Phenotypic Resistance of Rhipicephalus sanguineus sensu lato (Acari: Ixodidae) to Pyrethroids.

    Science.gov (United States)

    Klafke, G M; Miller, R J; Tidwell, J; Barreto, R; Guerrero, F D; Kaufman, P E; Pérez de León, A A

    2017-11-07

    The brown dog tick, Rhipicephalus sanguineus sensu lato (Latreille), is a cosmopolitan ectoparasite and vector of pathogens that kill humans and animals. Pyrethroids represent a class of synthetic acaricides that have been used intensely to try to control the brown dog tick and mitigate the risk of tick-borne disease transmission. However, acaricide resistance is an emerging problem in the management of the brown dog tick. Understanding the mechanism of resistance to acaricides, including pyrethroids, is important to adapt brown dog tick control strategies. The main objective of this study was to determine if target-site mutations associated with pyrethroid resistance in other pests could be associated with phenotypic resistance detected in a brown dog tick population from Florida. We amplified segment 6 of the domain III of the voltage-sensitive sodium channel protein, using cDNAs synthesized from pyrethroid-susceptible and pyrethroid-resistant tick strains. A single nucleotide point mutation (SNP) identified in a highly conserved region of domain III S6 in the resistant ticks resulted in an amino acid change from phenylalanine to leucine. This mutation is characteristic of resistance phenotypes in other tick species, and is the first report of this mutation in R. sanguineus. Molecular assays based on this knowledge could be developed to diagnose the risk for pyrethroid resistance, and to inform decisions on integrated brown dog tick management practices. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  5. Spontaneous excitation patterns computed for axons with injury-like impairments of sodium channels and Na/K pumps.

    Directory of Open Access Journals (Sweden)

    Na Yu

    Full Text Available In injured neurons, "leaky" voltage-gated sodium channels (Nav underlie dysfunctional excitability that ranges from spontaneous subthreshold oscillations (STO, to ectopic (sometimes paroxysmal excitation, to depolarizing block. In recombinant systems, mechanical injury to Nav1.6-rich membranes causes cytoplasmic Na(+-loading and "Nav-CLS", i.e., coupled left-(hyperpolarizing-shift of Nav activation and availability. Metabolic injury of hippocampal neurons (epileptic discharge results in comparable impairment: left-shifted activation and availability and hence left-shifted I(Na-window. A recent computation study revealed that CLS-based I(Na-window left-shift dissipates ion gradients and impairs excitability. Here, via dynamical analyses, we focus on sustained excitability patterns in mildly damaged nodes, in particular with more realistic Gaussian-distributed Nav-CLS to mimic "smeared" injury intensity. Since our interest is axons that might survive injury, pumps (sine qua non for live axons are included. In some simulations, pump efficacy and system volumes are varied. Impacts of current noise inputs are also characterized. The diverse modes of spontaneous rhythmic activity evident in these scenarios are studied using bifurcation analysis. For "mild CLS injury", a prominent feature is slow pump/leak-mediated E(Ion oscillations. These slow oscillations yield dynamic firing thresholds that underlie complex voltage STO and bursting behaviors. Thus, Nav-CLS, a biophysically justified mode of injury, in parallel with functioning pumps, robustly engenders an emergent slow process that triggers a plethora of pathological excitability patterns. This minimalist "device" could have physiological analogs. At first nodes of Ranvier and at nociceptors, e.g., localized lipid-tuning that modulated Nav midpoints could produce Nav-CLS, as could co-expression of appropriately differing Nav isoforms.

  6. Effect of voltage-gated sodium channels blockers on motility and viability of human sperm in vitro

    Directory of Open Access Journals (Sweden)

    Hammad Ahmad Gakhar

    2018-01-01

    Full Text Available Objective: To test the effect of voltage-gated sodium channels (VGSCs blockers on the motility and viability of human sperm in-vitro and to evaluate the tested compounds as potential contact spermicidal.Methods: Sperm samples were obtained from healthy nonsmoking volunteers of age 25-30 years who had not taken any drug 3 months before and during the course of the study. The effect of VGSCs blockers evaluated from two pharmacological classes including antiarrhythmic (amiodarone, procainamide and disopyramide and antiepileptic (carbamazepine, oxcarbazepine, phenytoin, and lamotrigine drugs. They were tested on the in-vitro motility and viability of human sperm using Computer Assisted Semen Analyzer.Results: All tested drugs except oxcarbazepine showed dose dependent inhibition of total motility with significant reduction (P<0.05 at the maximum concentration of 200 μΜ when compared with the control. The concentrations of drugs that reduced total sperm motility to 50% of control (half maximal inhibitory concentration were 2.76, 14.16 and 20.29 μΜ for phenytoin, lamotrigine and carbamazepine, respectively; and 2.53, 5.32 and 0.37 μΜ for amiodarone, procainamide and disopyramide, respectively. The anti-motility effects were reversible to various degrees. There was statistically insignificant difference in the inhibition of sperm viability among amiodarone, procainamide and disopyramide. Phenytoin demonstrated the most potent spermicidal action.Conclusions: VGSCs blockers have significant adverse effects on in-vitro motility of human spermatozoa. So in-vivo studies are required to determine their potential toxicological effects on human semen quality, which is an important factor regarding fertility. Moreover, these drugs have the potential to be developed into contact spermicidal.

  7. Electrophysiological and Pharmacological Analyses of Nav1.9 Voltage-Gated Sodium Channel by Establishing a Heterologous Expression System

    Directory of Open Access Journals (Sweden)

    Xi Zhou

    2017-11-01

    Full Text Available Nav1. 9 voltage-gated sodium channel is preferentially expressed in peripheral nociceptive neurons. Recent progresses have proved its role in pain sensation, but our understanding of Nav1.9, in general, has lagged behind because of limitations in heterologous expression in mammal cells. In this work, functional expression of human Nav1.9 (hNav1.9 was achieved by fusing GFP to the C-terminal of hNav1.9 in ND7/23 cells, which has been proved to be a reliable method to the electrophysiological and pharmacological studies of hNav1.9. By using the hNav1.9 expression system, we investigated the electrophysiological properties of four mutations of hNav1.9 (K419N, A582T, A842P, and F1689L, whose electrophysiological functions have not been determined yet. The four mutations significantly caused positive shift of the steady-state fast inactivation and therefore increased hNav1.9 activity, consistent with the phenotype of painful peripheral neuropathy. Meanwhile, the effects of inflammatory mediators on hNav1.9 were also investigated. Impressively, histamine was found for the first time to enhance hNav1.9 activity, indicating its vital role in hNav1.9 modulating inflammatory pain. Taken together, our research provided a useful platform for hNav1.9 studies and new insight into mechanism of hNav1.9 linking to pain.

  8. Knockdown resistance (kdr) of the voltage-gated sodium channel gene of Aedes aegypti population in Denpasar, Bali, Indonesia.

    Science.gov (United States)

    Hamid, Penny Humaidah; Prastowo, Joko; Widyasari, Anis; Taubert, Anja; Hermosilla, Carlos

    2017-06-05

    Aedes aegypti is the main vector of several arthropod-borne viral infections in the tropics profoundly affecting humans, such as dengue fever (DF), West Nile (WN), chikungunya and more recently Zika. Eradication of Aedes still largely depends on insecticides, which is the most cost-effective strategy, and often inefficient due to resistance development in exposed Aedes populations. We here conducted a study of Ae. aegypti resistance towards several insecticides regularly used in the city of Denpasar, Bali, Indonesia. Aedes aegypti egg samples were collected with ovitraps and thereafter hatched in the insectary of the Gadjah Mada University. The F0 generation was used for all bioassay-related experiments and knockdown resistance (kdr) assays. Results clearly showed resistance development of Ae. aegypti against tested insecticides. Mortalities of Ae. aegypti were less than 90% with highest resistance observed against 0.75% permethrin. Mosquitoes from the southern parts of Denpasar presented high level of resistance pattern in comparison to those from the western and northern parts of Denpasar. Kdr analysis of voltage-gated sodium channel (Vgsc) gene showed significant association to S989P and V1016G mutations linked to resistance phenotypes against 0.75% permethrin. Conversely, Ae. aegypti F1534C gene mutation did not result in any significant correlation to resistance development. Periodically surveillance of insecticide resistances in Ae. aegypti mosquitoes will help local public health authorities to set better goals and allow proper evaluation of on-going mosquito control strategies. Initial detection of insecticide resistance will contribute to conduct proper actions in delaying mosquito resistance development such as insecticide rotation or combination of compounds in order to prolong chemical efficacy in combating Ae. aegypti vectors in Indonesia.

  9. Correlative study between neuron-specific enolase and blood sugar level in ischemic stroke patients

    Directory of Open Access Journals (Sweden)

    Aparna Pandey

    2011-01-01

    Full Text Available Background: A study to investigate the level of the neurobiochemical marker, Neuron-Specific Enolase (NSE, at the time of admission and its correlation with the blood sugar level in ischemic stroke patients. Patients and Methods: We investigated 90 patients with complete stroke who were admitted to the Stroke Unit of the Department of Neurology at Sri Aurobindo Institute of Medical Sciences. NSE was measured with commercially available quantitative ′sandwich′ enzyme-linked immunosorbent assay kits obtained from R and D Systems. Hyperglycemia was defined as blood glucose concentration ≥ 7 mmol / L, and measured using the glucose oxidase method immediately. Results: Significantly increased NSE and lipid profile levels were found in ischemic stroke patients as compared to the control. Hyperglycemic ischemic stroke patients had increased levels of NSE, lipid profile, and National Institute of Health stroke scale scores (NIHSS score compared to normoglycemic ischemic stroke patients. In addition the serum NSE level of hyperglycemic stroke patients was also positively correlated with the blood sugar level (r = 0.734 P < 0.001. Conclusions: Hyperglycemia predicts an increased risk of poor outcome after ischemic stroke and it is reflected by a significantly increased level of Neuron-Specific Enolase.

  10. Gene expression profile of sodium channel subunits in the anterior cingulate cortex during experimental paclitaxel-induced neuropathic pain in mice

    Directory of Open Access Journals (Sweden)

    Willias Masocha

    2016-11-01

    Full Text Available Paclitaxel, a chemotherapeutic agent, causes neuropathic pain whose supraspinal pathophysiology is not fully understood. Dysregulation of sodium channel expression, studied mainly in the periphery and spinal cord level, contributes to the pathogenesis of neuropathic pain. We examined gene expression of sodium channel (Nav subunits by real time polymerase chain reaction (PCR in the anterior cingulate cortex (ACC at day 7 post first administration of paclitaxel, when mice had developed paclitaxel-induced thermal hyperalgesia. The ACC was chosen because increased activity in the ACC has been observed during neuropathic pain. In the ACC of vehicle-treated animals the threshold cycle (Ct values for Nav1.4, Nav1.5, Nav1.7, Nav1.8 and Nav1.9 were above 30 and/or not detectable in some samples. Thus, comparison in mRNA expression between untreated control, vehicle-treated and paclitaxel treated animals was done for Nav1.1, Nav1.2, Nav1.3, Nav1.6, Nax as well as Navβ1–Navβ4. There were no differences in the transcript levels of Nav1.1–Nav1.3, Nav1.6, Nax, Navβ1–Navβ3 between untreated and vehicle-treated mice, however, vehicle treatment increased Navβ4 expression. Paclitaxel treatment significantly increased the mRNA expression of Nav1.1, Nav1.2, Nav1.6 and Nax, but not Nav1.3, sodium channel alpha subunits compared to vehicle-treated animals. Treatment with paclitaxel significantly increased the expression of Navβ1 and Navβ3, but not Navβ2 and Navβ4, sodium channel beta subunits compared to vehicle-treated animals. These findings suggest that during paclitaxel-induced neuropathic pain (PINP there is differential upregulation of sodium channels in the ACC, which might contribute to the increased neuronal activity observed in the area during neuropathic pain.

  11. Grey relevant analysis of sodium critical heat flux in annular channel and the establishing of grey model

    International Nuclear Information System (INIS)

    Zhou Tao; Su Guanghui; Liao Yixiang; Zhang Weizhong; Qiu Suizheng; Jia Dounan

    1999-12-01

    Using grey systems theory and experimental data obtained from sodium boiling test loop in China, grey mutual analysis is done to some parameters influencing sodium CHF. The results of CHF are predicted by using GM (1,1) model. The GM(1,h) model is made up for creating CHF model. The results are in good agreement with the experimental data

  12. Development and validation of a thallium flux-based functional assay for the sodium channel NaV1.7 and its utility for lead discovery and compound profiling.

    Science.gov (United States)

    Du, Yu; Days, Emily; Romaine, Ian; Abney, Kris K; Kaufmann, Kristian; Sulikowski, Gary; Stauffer, Shaun; Lindsley, Craig W; Weaver, C David

    2015-06-17

    Ion channels are critical for life, and they are targets of numerous drugs. The sequencing of the human genome has revealed the existence of hundreds of different ion channel subunits capable of forming thousands of ion channels. In the face of this diversity, we only have a few selective small-molecule tools to aid in our understanding of the role specific ion channels in physiology which may in turn help illuminate their therapeutic potential. Although the advent of automated electrophysiology has increased the rate at which we can screen for and characterize ion channel modulators, the technique's high per-measurement cost and moderate throughput compared to other high-throughput screening approaches limit its utility for large-scale high-throughput screening. Therefore, lower cost, more rapid techniques are needed. While ion channel types capable of fluxing calcium are well-served by low cost, very high-throughput fluorescence-based assays, other channel types such as sodium channels remain underserved by present functional assay techniques. In order to address this shortcoming, we have developed a thallium flux-based assay for sodium channels using the NaV1.7 channel as a model target. We show that the assay is able to rapidly and cost-effectively identify NaV1.7 inhibitors thus providing a new method useful for the discovery and profiling of sodium channel modulators.

  13. Mutations in the voltage-gated sodium channel gene of anophelines and their association with resistance to pyrethroids - a review.

    Science.gov (United States)

    Silva, Ana Paula B; Santos, Joselita Maria M; Martins, Ademir J

    2014-10-07

    Constant and extensive use of chemical insecticides has created a selection pressure and favored resistance development in many insect species worldwide. One of the most important pyrethroid resistance mechanisms is classified as target site insensitivity, due to conformational changes in the target site that impair a proper binding of the insecticide molecule. The voltage-gated sodium channel (NaV) is the target of pyrethroids and DDT insecticides, used to control insects of medical, agricultural and veterinary importance, such as anophelines. It has been reported that the presence of a few non-silent point mutations in the NaV gene are associated with pyrethroid resistance, termed as 'kdr' (knockdown resistance) for preventing the knockdown effect of these insecticides. The presence of these mutations, as well as their effects, has been thoroughly studied in Anopheles mosquitoes. So far, kdr mutations have already been detected in at least 13 species (Anopheles gambiae, Anopheles arabiensis, Anopheles sinensis, Anopheles stephensi, Anopheles subpictus, Anopheles sacharovi, Anopheles culicifacies, Anopheles sundaicus, Anopheles aconitus, Anopheles vagus, Anopheles paraliae, Anopheles peditaeniatus and Anopheles albimanus) from populations of African, Asian and, more recently, American continents. Seven mutational variants (L1014F, L1014S, L1014C, L1014W, N1013S, N1575Y and V1010L) were described, with the highest prevalence of L1014F, which occurs at the 1014 site in NaV IIS6 domain. The increase of frequency and distribution of kdr mutations clearly shows the importance of this mechanism in the process of pyrethroid resistance. In this sense, several species-specific and highly sensitive methods have been designed in order to genotype individual mosquitoes for kdr in large scale, which may serve as important tolls for monitoring the dynamics of pyrethroid resistance in natural populations. We also briefly discuss investigations concerning the course of Plasmodium

  14. Larval application of sodium channel homologous dsRNA restores pyrethroid insecticide susceptibility in a resistant adult mosquito population.

    Science.gov (United States)

    Bona, Ana Caroline Dalla; Chitolina, Rodrigo Faitta; Fermino, Marise Lopes; de Castro Poncio, Lisiane; Weiss, Avital; Lima, José Bento Pereira; Paldi, Nitzan; Bernardes, Emerson Soares; Henen, Jonathan; Maori, Eyal

    2016-07-14

    Mosquitoes host and pass on to humans a variety of disease-causing pathogens such as infectious viruses and other parasitic microorganisms. The emergence and spread of insecticide resistance is threatening the effectiveness of current control measures for common mosquito vector borne diseases, such as malaria, dengue and Zika. Therefore, the emerging resistance to the widely used pyrethroid insecticides is an alarming problem for public health. Herein we demonstrated the use of RNA interference (RNAi) to increase susceptibility of adult mosquitoes to a widely used pyrethroid insecticide. Experiments were performed on a field-collected pyrethroid resistant strain of Ae. aegypti (Rio de Janeiro; RJ). Larvae from the resistant Ae. aegypti population were soaked with double-stranded RNAs (dsRNAs) that correspond either to voltage-gate sodium channel (VGSC), P-glycoprotein, or P450 detoxification genes and reared to adulthood. Adult mortality rates in the presence of various Deltamethrin pyrethroid concentrations were used to assess mosquito insecticide susceptibility. We characterized the RJ Ae. aegypti strain with regard to its level of resistance to a pyrethroid insecticide and found that it was approximately 6 times more resistant to Deltamethrin compared to the laboratory Rockefeller strain. The RJ strain displayed a higher frequency of Val1016Ile and Phe1534Cys substitutions of the VGSC gene. The resistant strain also displayed a higher basal expression level of VGSC compared to the Rockefeller strain. When dsRNA-treated mosquitoes were subjected to a standard pyrethroid contact bioassay, only dsRNA targeting VGSC increased the adult mortality of the pyrethroid resistant strain. The dsRNA treatment proved effective in increasing adult mosquito susceptibility over a range of pyrethroid concentrations and these results were associated with dsRNA-specific small interfering RNAs in treated adults, and the corresponding specific down regulation of VGSC gene expression

  15. Trans-Channel Interactions in Batrachotoxin-Modified Skeletal Muscle Sodium Channels: Voltage-Dependent Block by Cytoplasmic Amines, and the Influence of μ-Conotoxin GIIIA Derivatives and Permeant Ions

    Science.gov (United States)

    Pavlov, Evgeny; Britvina, Tatiana; McArthur, Jeff R.; Ma, Quanli; Sierralta, Iván; Zamponi, Gerald W.; French, Robert J.

    2008-01-01

    External μ-conotoxins and internal amine blockers inhibit each other's block of voltage-gated sodium channels. We explore the basis of this interaction by measuring the shifts in voltage-dependence of channel inhibition by internal amines induced by two μ-conotoxin derivatives with different charge distributions and net charges. Charge changes on the toxin were made at residue 13, which is thought to penetrate most deeply into the channel, making it likely to have the strongest individual interaction with an internal charged ligand. When an R13Q or R13E molecule was bound to the channel, the voltage dependence of diethylammonium (DEA)-block shifted toward more depolarized potentials (23 mV for R13Q, and 16 mV for R13E). An electrostatic model of the repulsion between DEA and the toxin simulated these data, with a distance between residue 13 of the μ-conotoxin and the DEA-binding site of ∼15 Å. Surprisingly, for tetrapropylammonium, the shifts were only 9 mV for R13Q, and 7 mV for R13E. The smaller shifts associated with R13E, the toxin with a smaller net charge, are generally consistent with an electrostatic interaction. However, the smaller shifts observed for tetrapropylammonium than for DEA suggest that other factors must be involved. Two observations indicate that the coupling of permeant ion occupancy of the channel to blocker binding may contribute to the overall amine-toxin interaction: 1), R13Q binding decreases the apparent affinity of sodium for the conducting pore by ∼4-fold; and 2), increasing external [Na+] decreases block by DEA at constant voltage. Thus, even though a number of studies suggest that sodium channels are occupied by no more than one ion most of the time, measurable coupling occurs between permeant ions and toxin or amine blockers. Such interactions likely determine, in part, the strength of trans-channel, amine-conotoxin interactions. PMID:18658222

  16. Trans-channel interactions in batrachotoxin-modified skeletal muscle sodium channels: voltage-dependent block by cytoplasmic amines, and the influence of mu-conotoxin GIIIA derivatives and permeant ions.

    Science.gov (United States)

    Pavlov, Evgeny; Britvina, Tatiana; McArthur, Jeff R; Ma, Quanli; Sierralta, Iván; Zamponi, Gerald W; French, Robert J

    2008-11-01

    External mu-conotoxins and internal amine blockers inhibit each other's block of voltage-gated sodium channels. We explore the basis of this interaction by measuring the shifts in voltage-dependence of channel inhibition by internal amines induced by two mu-conotoxin derivatives with different charge distributions and net charges. Charge changes on the toxin were made at residue 13, which is thought to penetrate most deeply into the channel, making it likely to have the strongest individual interaction with an internal charged ligand. When an R13Q or R13E molecule was bound to the channel, the voltage dependence of diethylammonium (DEA)-block shifted toward more depolarized potentials (23 mV for R13Q, and 16 mV for R13E). An electrostatic model of the repulsion between DEA and the toxin simulated these data, with a distance between residue 13 of the mu-conotoxin and the DEA-binding site of approximately 15 A. Surprisingly, for tetrapropylammonium, the shifts were only 9 mV for R13Q, and 7 mV for R13E. The smaller shifts associated with R13E, the toxin with a smaller net charge, are generally consistent with an electrostatic interaction. However, the smaller shifts observed for tetrapropylammonium than for DEA suggest that other factors must be involved. Two observations indicate that the coupling of permeant ion occupancy of the channel to blocker binding may contribute to the overall amine-toxin interaction: 1), R13Q binding decreases the apparent affinity of sodium for the conducting pore by approximately 4-fold; and 2), increasing external [Na(+)] decreases block by DEA at constant voltage. Thus, even though a number of studies suggest that sodium channels are occupied by no more than one ion most of the time, measurable coupling occurs between permeant ions and toxin or amine blockers. Such interactions likely determine, in part, the strength of trans-channel, amine-conotoxin interactions.

  17. TNF Lectin-Like Domain Restores Epithelial Sodium Channel Function in Frameshift Mutants Associated with Pseudohypoaldosteronism Type 1B

    Directory of Open Access Journals (Sweden)

    Anita Willam

    2017-05-01

    Full Text Available Previous in vitro studies have indicated that tumor necrosis factor (TNF activates amiloride-sensitive epithelial sodium channel (ENaC current through its lectin-like (TIP domain, since cyclic peptides mimicking the TIP domain (e.g., solnatide, showed ENaC-activating properties. In the current study, the effects of TNF and solnatide on individual ENaC subunits or ENaC carrying mutated glycosylation sites in the α-ENaC subunit were compared, revealing a similar mode of action for TNF and solnatide and corroborating the previous assumption that the lectin-like domain of TNF is the relevant molecular structure for ENaC activation. Accordingly, TNF enhanced ENaC current by increasing open probability of the glycosylated channel, position N511 in the α-ENaC subunit being identified as the most important glycosylation site. TNF significantly increased Na+ current through ENaC comprising only the pore forming subunits α or δ, was less active in ENaC comprising only β-subunits, and showed no effect on ENaC comprising γ-subunits. TNF did not increase the membrane abundance of ENaC subunits to the extent observed with solnatide. Since the α-subunit is believed to play a prominent role in the ENaC current activating effect of TNF and TIP, we investigated whether TNF and solnatide can enhance αβγ-ENaC current in α-ENaC loss-of-function frameshift mutants. The efficacy of solnatide has been already proven in pathological conditions involving ENaC in phase II clinical trials. The frameshift mutations αI68fs, αT169fs, αP197fs, αE272fs, αF435fs, αR438fs, αY447fs, αR448fs, αS452fs, and αT482fs have been reported to cause pseudohypoaldosteronism type 1B (PHA1B, a rare, life-threatening, salt-wasting disease, which hitherto has been treated only symptomatically. In a heterologous expression system, all frameshift mutants showed significantly reduced amiloride-sensitive whole-cell current compared to wild type αβγ-ENaC, whereas membrane

  18. Effects of the β1 auxiliary subunit on modification of Rat Na{sub v}1.6 sodium channels expressed in HEK293 cells by the pyrethroid insecticides tefluthrin and deltamethrin

    Energy Technology Data Exchange (ETDEWEB)

    He, Bingjun [College of Life Sciences, Nankai University, Tianjin 300071 (China); Soderlund, David M., E-mail: dms6@cornell.edu [Department of Entomology, Cornell University, Geneva, NY 14456 (United States)

    2016-01-15

    We expressed rat Na{sub v}1.6 sodium channels with or without the rat β1 subunit in human embryonic kidney (HEK293) cells and evaluated the effects of the pyrethroid insecticides tefluthrin and deltamethrin on whole-cell sodium currents. In assays with the Na{sub v}1.6 α subunit alone, both pyrethroids prolonged channel inactivation and deactivation and shifted the voltage dependence of channel activation and steady-state inactivation toward hyperpolarization. Maximal shifts in activation were ~ 18 mV for tefluthrin and ~ 24 mV for deltamethrin. These compounds also caused hyperpolarizing shifts of ~ 10–14 mV in the voltage dependence of steady-state inactivation and increased in the fraction of sodium current that was resistant to inactivation. The effects of pyrethroids on the voltage-dependent gating greatly increased the size of sodium window currents compared to unmodified channels; modified channels exhibited increased probability of spontaneous opening at membrane potentials more negative than the normal threshold for channel activation and incomplete channel inactivation. Coexpression of Na{sub v}1.6 with the β1 subunit had no effect on the kinetic behavior of pyrethroid-modified channels but had divergent effects on the voltage-dependent gating of tefluthrin- or deltamethrin-modified channels, increasing the size of tefluthrin-induced window currents but decreasing the size of corresponding deltamethrin-induced currents. Unexpectedly, the β1 subunit did not confer sensitivity to use-dependent channel modification by either tefluthrin or deltamethrin. We conclude from these results that functional reconstitution of channels in vitro requires careful attention to the subunit composition of channel complexes to ensure that channels in vitro are faithful functional and pharmacological models of channels in neurons. - Highlights: • We expressed Na{sub v}1.6 sodium channels with or without β1 subunits in HEK293 cells. • Tefluthrin and deltamethrin

  19. Substituted 4-phenyl-2-aminoimidazoles and 4-phenyl-4,5-dihydro-2-aminoimidazoles as voltage-gated sodium channel modulators.

    Science.gov (United States)

    Zidar, Nace; Jakopin, Žiga; Madge, David J; Chan, Fiona; Tytgat, Jan; Peigneur, Steve; Dolenc, Marija Sollner; Tomašić, Tihomir; Ilaš, Janez; Mašič, Lucija Peterlin; Kikelj, Danijel

    2014-03-03

    Voltage-gated sodium channels play an integral part in neurotransmission and their dysfunction is frequently a cause of various neurological disorders. On the basis of the structure of marine alkaloid clathrodin, twenty eight new analogs were designed, synthesized and tested for their ability to block human NaV1.3, NaV1.4 and NaV1.7 channels, as well as for their selectivity against human cardiac isoform NaV1.5, using automated patch clamp electrophysiological assay. Several compounds exhibited promising activities on different NaV channel isoforms in the medium micromolar range and some of the compounds showed also moderate isoform selectivities. The most promising results were obtained for the NaV1.3 channel, for which four compounds were found to possess IC₅₀ values lower than 15 μM. All of the active compounds bind to the open-inactivated states of the channels and therefore act as state-dependent modulators. The obtained results validate the approach of using natural products driven chemistry for drug discovery starting points and represent a good foundation for future design of selective NaV modulators. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

  20. Effect of mitochondrial potassium channel on the renal protection mediated by sodium thiosulfate against ethylene glycol induced nephrolithiasis in rat model

    Directory of Open Access Journals (Sweden)

    N. Baldev

    2015-12-01

    Full Text Available Purpose: Sodium thiosulfate (STS is clinically reported to be a promising drug in preventing nephrolithiasis. However, its mechanism of action remains unclear. In the present study, we investigated the role of mitochondrial KATP channel in the renal protection mediated by STS. Materials and Methods: Nephrolithiasis was induced in Wistar rats by administrating 0.4% ethylene glycol (EG along with 1% ammonium chloride for one week in drinking water followed by only 0.75% EG for two weeks. Treatment groups received STS, mitochondrial KATP channel opener and closer exclusively or in combination with STS for two weeks. Results: Animals treated with STS showed normal renal tissue architecture, supported by near normal serum creatinine, urea and ALP activity. Diazoxide (mitochondria KATP channel opening treatment to the animal also showed normal renal tissue histology and improved serum chemistry. However, an opposite result was shown by glibenclamide (mitochondria KATP channel closer treated rats. STS administered along with diazoxide negated the renal protection rendered by diazoxide alone, while it imparted protection to the glibenclamide treated rats, formulating a mitochondria modulated STS action. Conclusion: The present study confirmed that STS render renal protection not only through chelation and antioxidant effect but also by modulating the mitochondrial KATP channel for preventing urolithiasis.

  1. Sodium Channel Nav1.8 Underlies TTX-Resistant Axonal Action Potential Conduction in Somatosensory C-Fibers of Distal Cutaneous Nerves.

    Science.gov (United States)

    Klein, Amanda H; Vyshnevska, Alina; Hartke, Timothy V; De Col, Roberto; Mankowski, Joseph L; Turnquist, Brian; Bosmans, Frank; Reeh, Peter W; Schmelz, Martin; Carr, Richard W; Ringkamp, Matthias

    2017-05-17

    Voltage-gated sodium (Na V ) channels are responsible for the initiation and conduction of action potentials within primary afferents. The nine Na V channel isoforms recognized in mammals are often functionally divided into tetrodotoxin (TTX)-sensitive (TTX-s) channels (Na V 1.1-Na V 1.4, Na V 1.6-Na V 1.7) that are blocked by nanomolar concentrations and TTX-resistant (TTX-r) channels (Na V 1.8 and Na V 1.9) inhibited by millimolar concentrations, with Na V 1.5 having an intermediate toxin sensitivity. For small-diameter primary afferent neurons, it is unclear to what extent different Na V channel isoforms are distributed along the peripheral and central branches of their bifurcated axons. To determine the relative contribution of TTX-s and TTX-r channels to action potential conduction in different axonal compartments, we investigated the effects of TTX on C-fiber-mediated compound action potentials (C-CAPs) of proximal and distal peripheral nerve segments and dorsal roots from mice and pigtail monkeys ( Macaca nemestrina ). In the dorsal roots and proximal peripheral nerves of mice and nonhuman primates, TTX reduced the C-CAP amplitude to 16% of the baseline. In contrast, >30% of the C-CAP was resistant to TTX in distal peripheral branches of monkeys and WT and Na V 1.9 -/- mice. In nerves from Na V 1.8 -/- mice, TTX-r C-CAPs could not be detected. These data indicate that Na V 1.8 is the primary isoform underlying TTX-r conduction in distal axons of somatosensory C-fibers. Furthermore, there is a differential spatial distribution of Na V 1.8 within C-fiber axons, being functionally more prominent in the most distal axons and terminal regions. The enrichment of Na V 1.8 in distal axons may provide a useful target in the treatment of pain of peripheral origin. SIGNIFICANCE STATEMENT It is unclear whether individual sodium channel isoforms exert differential roles in action potential conduction along the axonal membrane of nociceptive, unmyelinated peripheral nerve

  2. Synthesis and biological evaluation of pyrrolidine derivatives as novel and potent sodium channel blockers for the treatment of ischemic stroke.

    Science.gov (United States)

    Seki, Maki; Tsuruta, Osamu; Tatsumi, Ryo; Soejima, Aki

    2013-07-15

    A novel series of pyrrolidine derivatives as Na(+) channel blockers was synthesized and evaluated for their inhibitory effects on neuronal Na(+) channels. Structure-activity relationship (SAR) studies of a pyrrolidine analogue 2 led to the discovery of 5e as a potent Na(+) channel blocker with a low inhibitory action against human ether-a-go-go-related gene (hERG) channels. Compound 5e showed remarkably neuroprotective activity in a rat transient middle cerebral artery occlusion (MCAO) model, suggesting that 5e would act as a neuroprotectant for ischemic stroke. Copyright © 2013 Elsevier Ltd. All rights reserved.

  3. Cardiac sodium channel Na(v)1.5 interacts with and is regulated by the protein tyrosine phosphatase PTPH1

    DEFF Research Database (Denmark)

    Jespersen, Thomas; Gavillet, Bruno; van Bemmelen, Miguel X

    2006-01-01

    In order to identify proteins interacting with the cardiac voltage-gated sodium channel Na(v)1.5, we used the last 66 amino acids of the C-terminus of the channel as bait to screen a human cardiac cDNA library. We identified the protein tyrosine phosphatase PTPH1 as an interacting protein. Pull......-down experiments confirmed the interaction, and indicated that it depends on the PDZ-domain binding motif of Na(v)1.5. Co-expression experiments in HEK293 cells showed that PTPH1 shifts the Na(v)1.5 availability relationship toward hyperpolarized potentials, whereas an inactive PTPH1 or the tyrosine kinase Fyn...... does the opposite. The results of this study suggest that tyrosine phosphorylation destabilizes the inactivated state of Na(v)1.5....

  4. Estradiol upregulates voltage-gated sodium channel 1.7 in trigeminal ganglion contributing to hyperalgesia of inflamed TMJ.

    Directory of Open Access Journals (Sweden)

    Rui-Yun Bi

    Full Text Available Temporomandibular disorders (TMDs have the highest prevalence in women of reproductive age. The role of estrogen in TMDs and especially in TMDs related pain is not fully elucidated. Voltage-gated sodium channel 1.7 (Nav1.7 plays a prominent role in pain perception and Nav1.7 in trigeminal ganglion (TG is involved in the hyperalgesia of inflamed Temporomandibular joint (TMJ. Whether estrogen could upregulate trigeminal ganglionic Nav1.7 expression to enhance hyperalgesia of inflamed TMJ remains to be explored.Estrous cycle and plasma levels of 17β-estradiol in female rats were evaluated with vaginal smear and enzyme linked immunosorbent assay, respectively. Female rats were ovariectomized and treated with 17β-estradiol at 0 μg, 20 μg and 80 μg, respectively, for 10 days. TMJ inflammation was induced using complete Freund's adjuvant. Head withdrawal thresholds and food intake were measured to evaluate the TMJ nociceptive responses. The expression of Nav1.7 in TG was examined using real-time PCR and western blot. The activity of Nav1.7 promoter was examined using luciferase reporter assay. The locations of estrogen receptors (ERα and ERβ, the G protein coupled estrogen receptor (GPR30, and Nav1.7 in TG were examined using immunohistofluorescence.Upregulation of Nav1.7 in TG and decrease in head withdrawal threshold were observed with the highest plasma 17β-estradiol in the proestrus of female rats. Ovariectomized rats treated with 80 μg 17β-estradiol showed upregulation of Nav1.7 in TG and decrease in head withdrawal threshold as compared with that of the control or ovariectomized rats treated with 0 μg or 20 μg. Moreover, 17β-estradiol dose-dependently potentiated TMJ inflammation-induced upregulation of Nav1.7 in TG and also enhanced TMJ inflammation-induced decrease of head withdrawal threshold in ovariectomized rats. In addition, the estrogen receptor antagonist, ICI 182,780, partially blocked the 17β-estradiol effect on Nav1

  5. Slack sodium-activated potassium channel membrane expression requires p38 mitogen-activated protein kinase phosphorylation.

    Science.gov (United States)

    Gururaj, Sushmitha; Fleites, John; Bhattacharjee, Arin

    2016-04-01

    p38 MAPK has long been understood as an inducible kinase under conditions of cellular stress, but there is now increasing evidence to support its role in the regulation of neuronal function. Several phosphorylation targets have been identified, an appreciable number of which are ion channels, implicating the possible involvement of p38 MAPK in neuronal excitability. The KNa channel Slack is an important protein to be studied as it is highly and ubiquitously expressed in DRG neurons and is important in the maintenance of their firing accommodation. We sought to examine if the Slack channel could be a substrate of p38 MAPK activity. First, we found that the Slack C-terminus contains two putative p38 MAPK phosphorylation sites that are highly conserved across species. Second, we show via electrophysiology experiments that KNa currents and further, Slack currents, are subject to tonic modulation by p38 MAPK. Third, biochemical approaches revealed that Slack channel regulation by p38 MAPK occurs through direct phosphorylation at the two putative sites of interaction, and mutating both sites prevented surface expression of Slack channels. Based on these results, we conclude that p38 MAPK is an obligate regulator of Slack channel function via the trafficking of channels into the membrane. The present study identifies Slack KNa channels as p38 MAPK substrates. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. A mutation (L1014F) in the voltage-gated sodium channel of the grain aphid, Sitobion avenae, is associated with resistance to pyrethroid insecticides.

    Science.gov (United States)

    Foster, Stephen P; Paul, Verity L; Slater, Russell; Warren, Anne; Denholm, Ian; Field, Linda M; Williamson, Martin S

    2014-08-01

    The grain aphid, Sitobion avenae Fabricius (Hemiptera: Aphididae), is an important pest of cereal crops. Pesticides are the main method for control but carry the risk of selecting for resistance. In response to reports of reduced efficacy of pyrethroid sprays applied to S. avenae, field samples were collected and screened for mutations in the voltage-gated sodium channel, the primary target site for pyrethroids. Aphid mobility and mortality to lambda-cyhalothrin were measured in coated glass vial bioassays. A single amino acid substitution (L1014F) was identified in the domain IIS6 segment of the sodium channel from the S. avenae samples exhibiting reduced pyrethroid efficacy. Bioassays on aphids heterozygous for the kdr mutation (SR) or homozygous for the wild-type allele (SS) showed that those carrying the mutation had significantly lower susceptibility to lambda-cyhalothrin. The L1014F (kdr) mutation, known to confer pyrethroid resistance in many insect pests, has been identified for the first time in S. avenae. Clonal lines heterozygous for the mutation showed 35-40-fold resistance to lambda-cyhalothrin in laboratory bioassays, consistent with the reported effect of this mutation on pyrethroid sensitivity in other aphid species. © 2013 Society of Chemical Industry.

  7. Development and utilization of a fluorescence-based receptor-binding assay for the site 5 voltage-sensitive sodium channel ligands brevetoxin and ciguatoxin.

    Science.gov (United States)

    McCall, Jennifer R; Jacocks, Henry M; Niven, Susan C; Poli, Mark A; Baden, Daniel G; Bourdelais, Andrea J

    2014-01-01

    Brevetoxins are a family of ladder-frame polyether toxins produced during blooms of the marine dinoflagellate Karenia brevis. Consumption of fish exposed to K. brevis blooms can lead to the development of neurotoxic shellfish poisoning. The toxic effects of brevetoxins are due to activation of voltage-sensitive sodium channels (VSSCs) in cell membranes. Binding of toxins has historically been measured using a radioligand competition assay that is fraught with difficulty. In this study, we developed a novel fluorescence-based binding assay for the brevetoxin receptor. Several fluorophores were conjugated to polyether brevetoxin-2 and used as the labeled ligand. Brevetoxin analogs were able to compete for binding with the fluorescent ligands. This assay was qualified against the standard radioligand receptor assay for the brevetoxin receptor. Furthermore, the fluorescence-based assay was used to determine relative concentrations of toxins in raw extracts of K. brevis culture, and to determine ciguatoxin affinity to site 5 of VSSCs. The fluorescence-based assay was quicker, safer, and far less expensive. As such, this assay can be used to replace the current radioligand assay and will be a vital tool for future experiments examining the binding affinity of various ligands for site 5 on sodium channels.

  8. GAPDH-mediated posttranscriptional regulations of sodium channel Scn1a and Scn3a genes under seizure and ketogenic diet conditions.

    Science.gov (United States)

    Lin, Guo-Wang; Lu, Ping; Zeng, Tao; Tang, Hui-Ling; Chen, Yong-Hong; Liu, Shu-Jing; Gao, Mei-Mei; Zhao, Qi-Hua; Yi, Yong-Hong; Long, Yue-Sheng

    2017-02-01

    Abnormal expressions of sodium channel SCN1A and SCN3A genes alter neural excitability that are believed to contribute to the pathogenesis of epilepsy, a long-term risk of recurrent seizures. Ketogenic diet (KD), a high-fat and low-carbohydrate treatment for difficult-to-control (refractory) epilepsy in children, has been suggested to reverse gene expression patterns. Here, we reveal a novel role of GAPDH on the posttranscriptional regulation of mouse Scn1a and Scn3a expressions under seizure and KD conditions. We show that GAPDH binds to a conserved region in the 3' UTRs of human and mouse SCN1A and SCN3A genes, which decreases and increases genes' expressions by affecting mRNA stability through SCN1A 3' UTR and SCN3A 3' UTR, respectively. In seizure mice, the upregulation and phosphorylation of GAPDH enhance its binding to the 3' UTR, which lead to downregulation of Scn1a and upregulation of Scn3a. Furthermore, administration of KD generates β-hydroxybutyric acid which rescues the abnormal expressions of Scn1a and Scn3a by weakening the GAPDH's binding to the element. Taken together, these data suggest that GAPDH-mediated expression regulation of sodium channel genes may be associated with epilepsy and the anticonvulsant action of KD. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Neuron-specific antioxidant OXR1 extends survival of a mouse model of amyotrophic lateral sclerosis.

    Science.gov (United States)

    Liu, Kevin X; Edwards, Benjamin; Lee, Sheena; Finelli, Mattéa J; Davies, Ben; Davies, Kay E; Oliver, Peter L

    2015-05-01

    Amyotrophic lateral sclerosis is a devastating neurodegenerative disorder characterized by the progressive loss of spinal motor neurons. While the aetiological mechanisms underlying the disease remain poorly understood, oxidative stress is a central component of amyotrophic lateral sclerosis and contributes to motor neuron injury. Recently, oxidation resistance 1 (OXR1) has emerged as a critical regulator of neuronal survival in response to oxidative stress, and is upregulated in the spinal cord of patients with amyotrophic lateral sclerosis. Here, we tested the hypothesis that OXR1 is a key neuroprotective factor during amyotrophic lateral sclerosis pathogenesis by crossing a new transgenic mouse line that overexpresses OXR1 in neurons with the SOD1(G93A) mouse model of amyotrophic lateral sclerosis. Interestingly, we report that overexpression of OXR1 significantly extends survival, improves motor deficits, and delays pathology in the spinal cord and in muscles of SOD1(G93A) mice. Furthermore, we find that overexpression of OXR1 in neurons significantly delays non-cell-autonomous neuroinflammatory response, classic complement system activation, and STAT3 activation through transcriptomic analysis of spinal cords of SOD1(G93A) mice. Taken together, these data identify OXR1 as the first neuron-specific antioxidant modulator of pathogenesis and disease progression in SOD1-mediated amyotrophic lateral sclerosis, and suggest that OXR1 may serve as a novel target for future therapeutic strategies. © The Author (2015). Published by Oxford University Press on behalf of the Guarantors of Brain.

  10. Neuron specific metabolic adaptations following multi-day exposures to oxygen glucose deprivation.

    Science.gov (United States)

    Zeiger, Stephanie L H; McKenzie, Jennifer R; Stankowski, Jeannette N; Martin, Jacob A; Cliffel, David E; McLaughlin, BethAnn

    2010-11-01

    Prior exposure to sub toxic insults can induce a powerful endogenous neuroprotective program known as ischemic preconditioning. Current models typically rely on a single stress episode to induce neuroprotection whereas the clinical reality is that patients may experience multiple transient ischemic attacks (TIAs) prior to suffering a stroke. We sought to develop a neuron-enriched preconditioning model using multiple oxygen glucose deprivation (OGD) episodes to assess the endogenous protective mechanisms neurons implement at the metabolic and cellular level. We found that neurons exposed to a five minute period of glucose deprivation recovered oxygen utilization and lactate production using novel microphysiometry techniques. Using the non-toxic and energetically favorable five minute exposure, we developed a preconditioning paradigm where neurons are exposed to this brief OGD for three consecutive days. These cells experienced a 45% greater survival following an otherwise lethal event and exhibited a longer lasting window of protection in comparison to our previous in vitro preconditioning model using a single stress. As in other models, preconditioned cells exhibited mild caspase activation, an increase in oxidized proteins and a requirement for reactive oxygen species for neuroprotection. Heat shock protein 70 was upregulated during preconditioning, yet the majority of this protein was released extracellularly. We believe coupling this neuron-enriched multi-day model with microphysiometry will allow us to assess neuronal specific real-time metabolic adaptations necessary for preconditioning. Copyright © 2010 Elsevier B.V. All rights reserved.

  11. Neuron- specific enolase level in patients with metabolic syndrome and its value forecasting acute stroke

    Directory of Open Access Journals (Sweden)

    Oral Ospanov

    2018-03-01

    Full Text Available Background Patients with metabolic syndrome are at a greater risk of experiencing a cerebrovascular event. Several studies show that patients with metabolic syndrome have asymptomatic ischemic brain injury. In this case, there is a need for rapid determination of asymptomatic brain lesions and prediction of acute stroke. Aims The aim of the study was to determine the neuron-specific enolase (NSE serum level in patients with metabolic syndrome and the value of this level for forecasting acute stroke. Methods The study used the following information to determine metabolic syndrome: waist circumference, total cholesterol, triglycerides, high-density lipoprotein cholesterol, blood pressure, and blood glucose. Doppler sonography mapping of the brachiocephalic trunk was held to determine the percentage of the carotid artery stenosis. To determine asymptomatic ischemic brain injury, the NSE serum marker was measured. Statistical processing of the measurements was performed using the H test and the Mann–Whitney test. The possible link between MS and NSE were determined by logistic regression analysis. Mathematical modeling was performed using logistic regression. Results There are statistically significant differences in NSE concentrations in groups with metabolic syndrome and ischemic stroke patients. This assertion is confirmed by logistic regression analysis, which revealed the existence of a relationship between metabolic syndrome and increased concentration of NSE. Conclusion Patients with metabolic syndrome have an increased concentration of NSE. This indicates the presence of asymptomatic ischemic neuronal damage. A prognostic model for determining the probability that patients with metabolic syndrome will have an acute stroke was developed.

  12. Rab27a regulates epithelial sodium channel (ENaC) activity through synaptotagmin-like protein (SLP-5) and Munc13-4 effector mechanism

    International Nuclear Information System (INIS)

    Saxena, Sunil K.; Horiuchi, Hisanori; Fukuda, Mitsunori

    2006-01-01

    Liddle's syndrome (excessive absorption of sodium ions) and PHA-1 (pseudohypoaldosteronism type 1) with decreased sodium absorption are caused by the mutations in the amiloride-sensitive epithelial sodium channel ENaC. Rab proteins are small GTPases involved in vesicle transport, docking, and fusion. Earlier, we reported that Rab27a inhibits ENaC-mediated currents through protein-protein interaction in HT-29 cells. We hereby report that Rab27a-dependent inhibition is associated with the GTP/GDP status as constitutively active or GTPase-deficient mutant Q78L inhibits amiloride-sensitive currents whereas GDP-locked inactive mutant T23N showed no effect. In order to further explore the molecular mechanism of this regulation, we performed competitive assays with two Rab27a-binding proteins: synaptotagmin-like protein (SLP-5) and Munc13-4 (a putative priming factor for exocytosis). Both proteins eliminate negative modulation of Rab27a on ENaC function. The SLP-5 reversal of Rab27a effect was restricted to C-terminal C2A/C2B domains assigned for putative phospholipids-binding function while the Rab27a-binding SHD motif imparted higher inhibition. The ENaC-mediated currents remain unaffected by Rab27a though SLP-5 appears to strongly bind it. The immunoprecipitation experiments suggest that in the presence of excessive Munc13-4 and SLP-5 proteins, Rab27a interaction with ENaC is diminished. Munc13-4 and SLP-5 limit the Rab27a availability to ENaC, thus minimizing its effect on channel function. These observations decisively prove that Rab27a inhibits ENaC function through a complex mechanism that involves GTP/GDP status, and protein-protein interactions involving Munc13-4 and SLP-5 effector proteins

  13. The natural scorpion peptide, BmK NT1 activates voltage-gated sodium channels and produces neurotoxicity in primary cultured cerebellar granule cells.

    Science.gov (United States)

    Zou, Xiaohan; He, Yuwei; Qiao, Jinping; Zhang, Chunlei; Cao, Zhengyu

    2016-01-01

    The scorpion Buthus martensii Karsch has been used in Traditional Chinese Medicine to treat neuronal diseases such as neuropathic pain, paralysis and epilepsy for thousands of years. Studies have demonstrated that scorpion venom is the primary active component. Although scorpion venom can effectively attenuate pain in the clinic, it also produces neurotoxic response. In this study, toxicity guided purification led to identify a mammalian toxin termed BmK NT1 comprising of 65 amino acid residues and an amidated C-terminus, a mature peptide encoded by the nucleotide sequence (GenBank No. AF464898). In contract to the recombinant product of the same nucleotide sequence, BmK AGAP, which displayed analgesic and anti-tumor effect, intravenous injection (i.v.) of BmK NT1 produced acute toxicity in mice with an LD50 value of 1.36 mg/kg. In primary cultured cerebellar granule cells, BmK NT1 produced a concentration-dependent cell death with an IC50 value of 0.65 μM (0.41-1.03 μM, 95% Confidence Intervals, 95% CI) which was abolished by TTX, a voltage-gated sodium channel (VGSC) blocker. We also demonstrated that BmK NT1 produced modest sodium influx in cerebellar granule cell cultures with an EC50 value of 2.19 μM (0.76-6.40 μM, 95% CI), an effect similar to VGSC agonist, veratridine. The sodium influx response was abolished by TTX suggesting that BmK NT1-induced sodium influx is solely through activation of VGSC. Considered these data together, we demonstrated that BmK NT1 activated VGSC and produced neurotoxicity in cerebellar granule cell cultures. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Voltage-gated sodium channel expression and action potential generation in differentiated NG108-15 cells.

    Science.gov (United States)

    Liu, Jinxu; Tu, Huiyin; Zhang, Dongze; Zheng, Hong; Li, Yu-Long

    2012-10-25

    The generation of action potential is required for stimulus-evoked neurotransmitter release in most neurons. Although various voltage-gated ion channels are involved in action potential production, the initiation of the action potential is mainly mediated by voltage-gated Na+ channels. In the present study, differentiation-induced changes of mRNA and protein expression of Na+ channels, Na+ currents, and cell membrane excitability were investigated in NG108-15 cells. Whole-cell patch-clamp results showed that differentiation (9 days) didn't change cell membrane excitability, compared to undifferentiated state. But differentiation (21 days) induced the action potential generation in 45.5% of NG108-15 cells (25/55 cells). In 9-day-differentiated cells, Na+ currents were mildly increased, which was also found in 21-day differentiated cells without action potential. In 21-day differentiated cells with action potential, Na+ currents were significantly enhanced. Western blot data showed that the expression of Na+ channels was increased with differentiated-time dependent manner. Single-cell real-time PCR data demonstrated that the expression of Na+ channel mRNA was increased by 21 days of differentiation in NG108-15 cells. More importantly, the mRNA level of Na+ channels in cells with action potential was higher than that in cells without action potential. Differentiation induces expression of voltage-gated Na+ channels and action potential generation in NG108-15 cells. A high level of the Na+ channel density is required for differentiation-triggered action potential generation.

  15. Activation of sodium channels by α-scorpion toxin, BmK NT1, produced neurotoxicity in cerebellar granule cells: an association with intracellular Ca2+ overloading.

    Science.gov (United States)

    He, Yuwei; Zou, Xiaohan; Li, Xichun; Chen, Juan; Jin, Liang; Zhang, Fan; Yu, Boyang; Cao, Zhengyu

    2017-02-01

    Voltage-gated sodium channels (VGSCs) are responsible for the action potential generation in excitable cells including neurons and involved in many physiological and pathological processes. Scorpion toxins are invaluable tools to explore the structure and function of ion channels. BmK NT1, a scorpion toxin from Buthus martensii Karsch, stimulates sodium influx in cerebellar granule cells (CGCs). In this study, we characterized the mode of action of BmK NT1 on the VGSCs and explored the cellular response in CGC cultures. BmK NT1 delayed the fast inactivation of VGSCs, increased the Na + currents, and shifted the steady-state activation and inactivation to more hyperpolarized membrane potential, which was similar to the mode of action of α-scorpion toxins. BmK NT1 stimulated neuron death (EC 50  = 0.68 µM) and produced massive intracellular Ca 2+ overloading (EC 50  = 0.98 µM). TTX abrogated these responses, suggesting that both responses were subsequent to the activation of VGSCs. The Ca 2+ response of BmK NT1 was primary through extracellular Ca 2+ influx since reducing the extracellular Ca 2+ concentration suppressed the Ca 2+ response. Further pharmacological evaluation demonstrated that BmK NT1-induced Ca 2+ influx and neurotoxicity were partially blocked either by MK-801, an NMDA receptor blocker, or by KB-R7943, an inhibitor of Na + /Ca 2+ exchangers. Nifedipine, an L-type Ca 2+ channel inhibitor, slightly suppressed both Ca 2+ response and neurotoxicity. A combination of these three inhibitors abrogated both responses. Considered together, these data ambiguously demonstrated that activation of VGSCs by an α-scorpion toxin was sufficient to produce neurotoxicity which was associated with intracellular Ca 2+ overloading through both NMDA receptor- and Na + /Ca 2+ exchanger-mediated Ca 2+ influx.

  16. The human Nav1.5 F1486 deletion associated with long QT syndrome leads to impaired sodium channel inactivation and reduced lidocaine sensitivity

    Science.gov (United States)

    Song, Weihua; Xiao, Yucheng; Chen, Hanying; Ashpole, Nicole M; Piekarz, Andrew D; Ma, Peilin; Hudmon, Andy; Cummins, Theodore R; Shou, Weinian

    2012-01-01

    The deletion of phenylalanine 1486 (F1486del) in the human cardiac voltage-gated sodium channel (hNav1.5) is associated with fatal long QT (LQT) syndrome. In this study we determined how F1486del impairs the functional properties of hNav1.5 and alters action potential firing in heterologous expression systems (human embryonic kidney (HEK) 293 cells) and their native cardiomyocyte background. Cells expressing hNav1.5-F1486del exhibited a loss-of-function alteration, reflected by an 80% reduction of peak current density, and several gain-of-function alterations, including reduced channel inactivation, enlarged window current, substantial augmentation of persistent late sodium current and an increase in ramp current. We also observed substantial action potential duration (APD) prolongation and prominent early afterdepolarizations (EADs) in neonatal cardiomyocytes expressing the F1486del channels, as well as in computer simulations of myocyte activity. In addition, lidocaine sensitivity was dramatically reduced, which probably contributed to the poor therapeutic outcome observed in the patient carrying the hNav1.5-F1486del mutation. Therefore, despite the significant reduction in peak current density, the F1486del mutation also leads to substantial gain-of-function alterations that are sufficient to cause APD prolongation and EADs, the predominant characteristic of LQTs. These data demonstrate that hNav1.5 mutations can have complex functional consequences and highlight the importance of identifying the specific molecular defect when evaluating potential treatments for individuals with prolonged QT intervals. PMID:22826127

  17. Neuron-specific enolase is a useful maker of neuroendocrine origin in pheochromocytoma cell culture

    International Nuclear Information System (INIS)

    Abelin, N.; Dahia, P.L.M.; Martin, R.; Kato, S.; Toledo, S.P.A.

    1994-01-01

    Neuron-specific enolase (NSE) has been used as a marker for neuroendocrine tumors either in immunocytochemical studies or in serum measurements. In this paper NSE levels were determined in cultured pheochromocytoma cells to test whether it is also a useful marker in cell culture of tumors derived from neuroendocrine system. Cultured pheochromocytoma cells came from a primary explant and were grown in RPMI supplemented with 20% fetal calf serum, 100 μg/mL ampicillin and 100 μ/mL streptomycin. NSE was measured in culture medium and cell homogenates. Samples from different pheochromocytoma cultures were analyzed and compared to normal cultured fibroblast cells derived from human skin. NSE was measured by a commercially available radioimmunoassay kit. NSE levels were higher in cell homogenates as compared to those in culture medium, reaching levels as high as 6-fold in the former in TE cell line (26.46 ng/mL and 4.39 ng/mL, respectively). Serial measurements in culture medium from TE cell line evidenced decreasing values in subsequential subcultures (from 9.24 ng/mL during primary explant to 1.7 ng/mL in the tenth subculture). In cultured normal fibroblasts, NSE levels in cultured media were definitely lower than those obtained from pheochromocytoma cultures. These preliminary data suggest that NSE may be a useful marker of neuroendocrine derived tumors, such as pheochromocytoma, in culture. Thus, the simplicity and availability of NSE radioimmunoassay provides an alternative to catecholamine measurement to better characterize pheochromocytoma cell lines in culture, with the advantage of faster result at lower costs. (author). 18 refs, 2 tabs

  18. Serum neuron specific enolase - a novel indicator for neuropsychiatric systemic lupus erythematosus?

    Science.gov (United States)

    Hawro, T; Bogucki, A; Krupińska-Kun, M; Maurer, M; Woźniacka, A

    2015-12-01

    Neuropsychiatric (NP) lupus, a common manifestation of systemic lupus erythematosus (SLE), is still insufficiently understood, in part, because of the lack of specific biomarkers. Neuron specific enolase (NSE), an important neuronal glycolytic enzyme, shows increased serum levels following acute brain injury, and decreased serum levels in several chronic disorders of the nervous system, including multi infarct dementia, multiple sclerosis and depression. The aim of the study was to evaluate serum NSE levels in SLE patients with and without nervous system involvement, and in healthy controls, and to assess the correlation of NSE serum levels of patients with neuropsychiatric systemic lupus erythematosus (NPSLE) with clinical parameters. The study comprised 47 SLE patients and 28 controls. SLE activity was assessed using the Systemic Lupus Activity Measure (SLAM). A neurologist and a psychiatrist examined all patients. NP involvement was diagnosed according to strict NPSLE criteria proposed by Ainiala and coworkers, as modification to American College of Rheumatology (ACR) nomenclature and case definitions. NSE serum levels were determined by use of an immunoassay. Mean NSE serum concentrations in patients with NPSLE were significantly lower than in non-NPSLE patients (6.3 ± 2.6 µg/L vs. 9.7 ± 3.3 µg/L, p < 0.01) and in controls (8.8 ± 3.3 µg/L, p < 0.05). There were significant negative correlations between NSE serum levels and SLE activity (r = -0.42, p < 0.05) and the number of NPSLE manifestations diagnosed (-0.37; p = 0.001). Decreased serum concentrations of NSE may reflect chronic neuronal damage with declined metabolism of the nervous tissue in patients with NPSLE. © The Author(s) 2015.

  19. The relationship between neuron-specific enolase and prognosis of patients with acute traumatic brain injury

    Directory of Open Access Journals (Sweden)

    Yun-yang LIU

    2015-03-01

    Full Text Available Objective To investigate the relationship between neuron-specific enolase (NSE levels in serum and cerebrospinal fluid (CSF of patients with acute traumatic brain injury (TBI and the prognosis of TBI patients.  Methods A total of 89 patients with acute TBI were divided into light, medium, heavy and severe TBI groups based on admission Glasgow Coma Scale (GCS score. Serum NSE expression levels were detected in all cases and NSE levels in CSF were detected in 18 cases within 12 h after TBI. The expression levels of serum NSE in 20 normal people, except cases of lung disease and nervous system damage, were detected as a control group. Results Compared with the control group, serum NSE expression levels of patients in each TBI group were elevated (P < 0.05, for all, and the NSE levels in severe and heavy TBI groups were higher than that in medium and light groups (P < 0.05, for all. The serum NSE expression levels of patients with cerebral contusion were higher than that of patients with diffuse axonal injury (DAI, P = 0.025, subdural hematoma (P = 0.031 and epidural hematoma (P = 0.021. Serum NSE expression levels were negatively correlated with GCS score (rs = - 0.327, P = 0.024 and Glasgow Outcome Scale (GOS score (rs = - 0.252, P = 0.049. The NSE expression levels of CSF in severe and heavy TBI patients were higher than that of serum (P = 0.039, 0.031.  Conclusions NSE expression changes can be evaluated as an auxiliary indicator in reflecting the degree of acute TBI, typing diagnosis and prognostic evaluation, and NSE levels of CSF is more sensitive than that of serum. DOI: 10.3969/j.issn.1672-6731.2015.03.013

  20. Crystal Structure of the Mammalian GIRK2 K+ Channel and Gating Regulation by G-Proteins, PIP2 and Sodium

    Science.gov (United States)

    Whorton, Matthew R.; MacKinnon, Roderick

    2011-01-01

    Summary G-protein-gated K+ channels (Kir3.1–Kir3.4) control electrical excitability in many different cells. Among their functions relevant to human physiology and disease, they regulate the heart rate and govern a wide range of neuronal activities. Here we present the first crystal structures of a G-protein-gated K+ channel. By comparing the wild-type structure to that of a constitutively active mutant, we identify a global conformational change through which G-proteins could open a G-loop gate in the cytoplasmic domain. The structures of both channels in the absence and presence of PIP2 show that G-proteins open only the G-loop gate in the absence of PIP2, but in the presence of PIP2 the G-loop gate and a second inner helix gate become coupled, so that both gates open. We also identify a strategically located Na+ ion-binding site, which would allow intracellular Na+ to modulate GIRK channel activity. These data provide a mechanistic description of multi-ligand regulation of GIRK channel gating. PMID:21962516

  1. Multi-country Survey Revealed Prevalent and Novel F1534S Mutation in Voltage-Gated Sodium Channel (VGSC Gene in Aedes albopictus.

    Directory of Open Access Journals (Sweden)

    Jiabao Xu

    2016-05-01

    Full Text Available Aedes albopictus is an important dengue vector because of its aggressive biting behavior and rapid spread out of its native home range in Southeast Asia. Pyrethroids are widely used for adult mosquito control, and resistance to pyrethroids should be carefully monitored because vector control is the only effective method currently available to prevent dengue transmission. The voltage-gated sodium channel gene is the target site of pyrethroids, and mutations in this gene cause knockdown resistance (kdr. Previous studies reported various mutations in the voltage-gated sodium channel (VGSC gene, but the spatial distribution of kdr mutations in Ae. albopictus has not been systematically examined, and the association between kdr mutation and phenotypic resistance has not been established.A total of 597 Ae. albopictus individuals from 12 populations across Asia, Africa, America and Europe were examined for mutations in the voltage-gated sodium channel gene. Three domains for a total of 1,107 bp were sequenced for every individual. Two populations from southern China were examined for pyrethroid resistance using the World Health Organization standard tube bioassay, and the association between kdr mutations and phenotypic resistance was tested.A total of 29 synonymous mutations were found across domain II, III and IV of the VGSC gene. Non-synonymous mutations in two codons of the VGSC gene were detected in 5 populations from 4 countries. A novel mutation at 1532 codon (I1532T was found in Rome, Italy with a frequency of 19.7%. The second novel mutation at codon 1534 (F1534S was detected in southern China and Florida, USA with a frequency ranging from 9.5-22.6%. The WHO insecticide susceptibility bioassay found 90.1% and 96.1% mortality in the two populations from southern China, suggesting resistance and probable resistance. Positive association between kdr mutations with deltamethrin resistance was established in these two populations.Two novel kdr

  2. Multi-country Survey Revealed Prevalent and Novel F1534S Mutation in Voltage-Gated Sodium Channel (VGSC) Gene in Aedes albopictus.

    Science.gov (United States)

    Xu, Jiabao; Bonizzoni, Mariangela; Zhong, Daibin; Zhou, Guofa; Cai, Songwu; Li, Yiji; Wang, Xiaoming; Lo, Eugenia; Lee, Rebecca; Sheen, Roger; Duan, Jinhua; Yan, Guiyun; Chen, Xiao-Guang

    2016-05-01

    Aedes albopictus is an important dengue vector because of its aggressive biting behavior and rapid spread out of its native home range in Southeast Asia. Pyrethroids are widely used for adult mosquito control, and resistance to pyrethroids should be carefully monitored because vector control is the only effective method currently available to prevent dengue transmission. The voltage-gated sodium channel gene is the target site of pyrethroids, and mutations in this gene cause knockdown resistance (kdr). Previous studies reported various mutations in the voltage-gated sodium channel (VGSC) gene, but the spatial distribution of kdr mutations in Ae. albopictus has not been systematically examined, and the association between kdr mutation and phenotypic resistance has not been established. A total of 597 Ae. albopictus individuals from 12 populations across Asia, Africa, America and Europe were examined for mutations in the voltage-gated sodium channel gene. Three domains for a total of 1,107 bp were sequenced for every individual. Two populations from southern China were examined for pyrethroid resistance using the World Health Organization standard tube bioassay, and the association between kdr mutations and phenotypic resistance was tested. A total of 29 synonymous mutations were found across domain II, III and IV of the VGSC gene. Non-synonymous mutations in two codons of the VGSC gene were detected in 5 populations from 4 countries. A novel mutation at 1532 codon (I1532T) was found in Rome, Italy with a frequency of 19.7%. The second novel mutation at codon 1534 (F1534S) was detected in southern China and Florida, USA with a frequency ranging from 9.5-22.6%. The WHO insecticide susceptibility bioassay found 90.1% and 96.1% mortality in the two populations from southern China, suggesting resistance and probable resistance. Positive association between kdr mutations with deltamethrin resistance was established in these two populations. Two novel kdr mutations, I1532T

  3. DRG Voltage-Gated Sodium Channel 1.7 Is Upregulated in Paclitaxel-Induced Neuropathy in Rats and in Humans with Neuropathic Pain.

    Science.gov (United States)

    Li, Yan; North, Robert Y; Rhines, Laurence D; Tatsui, Claudio Esteves; Rao, Ganesh; Edwards, Denaya D; Cassidy, Ryan M; Harrison, Daniel S; Johansson, Caj A; Zhang, Hongmei; Dougherty, Patrick M

    2018-01-31

    Chemotherapy-induced peripheral neuropathy (CIPN) is a common adverse effect experienced by cancer patients receiving treatment with paclitaxel. The voltage-gated sodium channel 1.7 (Na v 1.7) plays an important role in multiple preclinical models of neuropathic pain and in inherited human pain phenotypes, and its gene expression is increased in dorsal root ganglia (DRGs) of paclitaxel-treated rats. Hence, the potential of change in the expression and function of Na v 1.7 protein in DRGs from male rats with paclitaxel-related CIPN and from male and female humans with cancer-related neuropathic pain was tested here. Double immunofluorescence in CIPN rats showed that Na v 1.7 was upregulated in small DRG neuron somata, especially those also expressing calcitonin gene-related peptide (CGRP), and in central processes of these cells in the superficial spinal dorsal horn. Whole-cell patch-clamp recordings in rat DRG neurons revealed that paclitaxel induced an enhancement of ProTx II (a selective Na v 1.7 channel blocker)-sensitive sodium currents. Bath-applied ProTx II suppressed spontaneous action potentials in DRG neurons occurring in rats with CIPN, while intrathecal injection of ProTx II significantly attenuated behavioral signs of CIPN. Complementarily, DRG neurons isolated from segments where patients had a history of neuropathic pain also showed electrophysiological and immunofluorescence results indicating an increased expression of Na v 1.7 associated with spontaneous activity. Na v 1.7 was also colocalized in human cells expressing transient receptor potential vanilloid 1 and CGRP. Furthermore, ProTx II decreased firing frequency in human DRGs with spontaneous action potentials. This study suggests that Na v 1.7 may provide a potential new target for the treatment of neuropathic pain, including chemotherapy (paclitaxel)-induced neuropathic pain. SIGNIFICANCE STATEMENT This work demonstrates that the expression and function of the voltage-gated sodium channel Na

  4. Molecular determinants of voltage-gated sodium channel regulation by the Nedd4/Nedd4-like proteins

    DEFF Research Database (Denmark)

    Rougier, Jean-Sébastien; van Bemmelen, Miguel X; Bruce, M Christine

    2004-01-01

    -ubiquitin ligases of the Nedd4 family. We recently reported that cardiac Na(v)1.5 is regulated by Nedd4-2. In this study, we further investigated the molecular determinants of regulation of Na(v) proteins. When expressed in HEK-293 cells and studied using whole cell voltage clamping, the neuronal Na(v)1.2 and Na...... that Nedd4-dependent ubiquitination of Na(v) channels may represent a general mechanism regulating the excitability of neurons and myocytes via modulation of channel density at the plasma membrane....

  5. Investigations of the Navβ1b sodium channel subunit in human ventricle; functional characterization of the H162P Brugada Syndrome mutant

    DEFF Research Database (Denmark)

    Yuan, Lei; Koivumaki, Jussi; Liang, Bo

    2014-01-01

    Brugada Syndrome (BrS) is a rare inherited disease which can give rise to ventricular arrhythmia and ultimately sudden cardiac death. Numerous loss-of-function mutations in the cardiac sodium channel Nav1.5 have been associated with BrS. However, few mutations in the auxiliary Navβ1-4 subunits ha...... density was reduced by 48 % (-645±151 vs - 334±71 pA/pF), V1/2 steady-state inactivation shifted by -6.7 mV (-70.3±1.5 vs. -77.0±2.8 mV), and time-dependent recovery from inactivation slowed by more than 50% as compared to co-expression with Navβ1b WT. Computer simulations revealed...

  6. A single Markov-type kinetic model accounting for the macroscopic currents of all human voltage-gated sodium channel isoforms.

    Science.gov (United States)

    Balbi, Pietro; Massobrio, Paolo; Hellgren Kotaleski, Jeanette

    2017-09-01

    Modelling ionic channels represents a fundamental step towards developing biologically detailed neuron models. Until recently, the voltage-gated ion channels have been mainly modelled according to the formalism introduced by the seminal works of Hodgkin and Huxley (HH). However, following the continuing achievements in the biophysical and molecular comprehension of these pore-forming transmembrane proteins, the HH formalism turned out to carry limitations and inconsistencies in reproducing the ion-channels electrophysiological behaviour. At the same time, Markov-type kinetic models have been increasingly proven to successfully replicate both the electrophysiological and biophysical features of different ion channels. However, in order to model even the finest non-conducting molecular conformational change, they are often equipped with a considerable number of states and related transitions, which make them computationally heavy and less suitable for implementation in conductance-based neurons and large networks of those. In this purely modelling study we develop a Markov-type kinetic model for all human voltage-gated sodium channels (VGSCs). The model framework is detailed, unifying (i.e., it accounts for all ion-channel isoforms) and computationally efficient (i.e. with a minimal set of states and transitions). The electrophysiological data to be modelled are gathered from previously published studies on whole-cell patch-clamp experiments in mammalian cell lines heterologously expressing the human VGSC subtypes (from NaV1.1 to NaV1.9). By adopting a minimum sequence of states, and using the same state diagram for all the distinct isoforms, the model ensures the lightest computational load when used in neuron models and neural networks of increasing complexity. The transitions between the states are described by original ordinary differential equations, which represent the rate of the state transitions as a function of voltage (i.e., membrane potential). The

  7. Tarantula huwentoxin-IV inhibits neuronal sodium channels by binding to receptor site 4 and trapping the domain ii voltage sensor in the closed configuration.

    Science.gov (United States)

    Xiao, Yucheng; Bingham, Jon-Paul; Zhu, Weiguo; Moczydlowski, Edward; Liang, Songping; Cummins, Theodore R

    2008-10-03

    Peptide toxins with high affinity, divergent pharmacological functions, and isoform-specific selectivity are powerful tools for investigating the structure-function relationships of voltage-gated sodium channels (VGSCs). Although a number of interesting inhibitors have been reported from tarantula venoms, little is known about the mechanism for their interaction with VGSCs. We show that huwentoxin-IV (HWTX-IV), a 35-residue peptide from tarantula Ornithoctonus huwena venom, preferentially inhibits neuronal VGSC subtypes rNav1.2, rNav1.3, and hNav1.7 compared with muscle subtypes rNav1.4 and hNav1.5. Of the five VGSCs examined, hNav1.7 was most sensitive to HWTX-IV (IC(50) approximately 26 nM). Following application of 1 microm HWTX-IV, hNav1.7 currents could only be elicited with extreme depolarizations (>+100 mV). Recovery of hNav1.7 channels from HWTX-IV inhibition could be induced by extreme depolarizations or moderate depolarizations lasting several minutes. Site-directed mutagenesis analysis indicated that the toxin docked at neurotoxin receptor site 4 located at the extracellular S3-S4 linker of domain II. Mutations E818Q and D816N in hNav1.7 decreased toxin affinity for hNav1.7 by approximately 300-fold, whereas the reverse mutations in rNav1.4 (N655D/Q657E) and the corresponding mutations in hNav1.5 (R812D/S814E) greatly increased the sensitivity of the muscle VGSCs to HWTX-IV. Our data identify a novel mechanism for sodium channel inhibition by tarantula toxins involving binding to neurotoxin receptor site 4. In contrast to scorpion beta-toxins that trap the IIS4 voltage sensor in an outward configuration, we propose that HWTX-IV traps the voltage sensor of domain II in the inward, closed configuration.

  8. Comparative study of the distribution of the alpha-subunits of voltage-gated sodium channels in normal and axotomized rat dorsal root ganglion neurons.

    Science.gov (United States)

    Fukuoka, Tetsuo; Kobayashi, Kimiko; Yamanaka, Hiroki; Obata, Koichi; Dai, Yi; Noguchi, Koichi

    2008-09-10

    We compared the distribution of the alpha-subunit mRNAs of voltage-gated sodium channels Nav1.1-1.3 and Nav1.6-1.9 and a related channel, Nax, in histochemically identified neuronal subpopulations of the rat dorsal root ganglia (DRG). In the naïve DRG, the expression of Nav1.1 and Nav1.6 was restricted to A-fiber neurons, and they were preferentially expressed by TrkC neurons, suggesting that proprioceptive neurons possess these channels. Nav1.7, -1.8, and -1.9 mRNAs were more abundant in C-fiber neurons compared with A-fiber ones. Nax was evenly expressed in both populations. Although Nav1.8 and -1.9 were preferentially expressed by TrkA neurons, other alpha-subunits were expressed independently of TrkA expression. Actually, all IB4(+) neurons expressed both Nav1.8 and -1.9, and relatively limited subpopulations of IB4(+) neurons (3% and 12%, respectively) expressed Nav1.1 and/or Nav1.6. These findings provide useful information in interpreting the electrophysiological characteristics of some neuronal subpopulations of naïve DRG. After L5 spinal nerve ligation, Nav1.3 mRNA was up-regulated mainly in A-fiber neurons in the ipsilateral L5 DRG. Although previous studies demonstrated that nerve growth factor (NGF) and glial cell-derived neurotrophic factor (GDNF) reversed this up-regulation, the Nav1.3 induction was independent of either TrkA or GFRalpha1 expression, suggesting that the induction of Nav1.3 may be one of the common responses of axotomized DRG neurons without a direct relationship to NGF/GDNF supply. (c) 2008 Wiley-Liss, Inc.

  9. Calculation of spin-dependent observables in electron-sodium scattering using the coupled-channel optical method

    International Nuclear Information System (INIS)

    Bray, Igor.

    1992-04-01

    The calculations of the 3 2 S and 3 2 P spin asymmetries and the angular momentum for singlet and triplet scattering for projectile energies of 10 and 20 eV is presented. Together these observables give a most stringent test of any electron-atom scattering theory. An excellent agreement was found between the results of the coupled-channel optical method and experiment, which for the spin asymmetries can only be obtained by a good description of the couplings between the lower-lying target states and the target continuum. 10 refs., 2 figs

  10. Sodium leak channel, non-selective contributes to the leak current in human myometrial smooth muscle cells from pregnant women.

    Science.gov (United States)

    Reinl, Erin L; Cabeza, Rafael; Gregory, Ismail A; Cahill, Alison G; England, Sarah K

    2015-10-01

    Uterine contractions are tightly regulated by the electrical activity of myometrial smooth muscle cells (MSMCs). These cells require a depolarizing current to initiate Ca(2+) influx and induce contraction. Cationic leak channels, which permit a steady flow of cations into a cell, are known to cause membrane depolarization in many tissue types. Previously, a Gd(3+)-sensitive, Na(+)-dependent leak current was identified in the rat myometrium, but the presence of such a current in human MSMCs and the specific ion channel conducting this current was unknown. Here, we report the presence of a Na(+)-dependent leak current in human myometrium and demonstrate that the Na(+)-leak channel, NALCN, contributes to this current. We performed whole-cell voltage-clamp on fresh and cultured MSMCs from uterine biopsies of term, non-laboring women and isolated the leak currents by using Ca(2+) and K(+) channel blockers in the bath solution. Ohmic leak currents were identified in freshly isolated and cultured MSMCs with normalized conductances of 14.6 pS/pF and 10.0 pS/pF, respectively. The myometrial leak current was significantly reduced (P < 0.01) by treating cells with 10 μM Gd(3+) or by superfusing the cells with a Na(+)-free extracellular solution. Reverse transcriptase PCR and immunoblot analysis of uterine biopsies from term, non-laboring women revealed NALCN messenger RNA and protein expression in the myometrium. Notably, ∼90% knockdown of NALCN protein expression with lentivirus-delivered shRNA reduced the Gd(3+)-sensitive leak current density by 42% (P < 0.05). Our results reveal that NALCN, in part, generates the leak current in MSMCs and provide the basis for future research assessing NALCN as a potential molecular target for modulating uterine excitability. © The Author 2015. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  11. Anticonvulsant mechanism of saponins fraction from adventitious roots of Ficus religiosa: possible modulation of GABAergic, calcium and sodium channel functions

    Directory of Open Access Journals (Sweden)

    Damanpreet Singh

    Full Text Available ABSTRACT In our previous studies, quantified saponins-rich fraction from adventitious root extract of Ficus religiosa L., Moraceae, showed anticonvulsant effect in acute, as well as chronic mice models of epilepsy. The present study was designed to reveal putative anticonvulsant mechanism of quantified saponins-rich fraction using target specific animal models. The anticonvulsant effect of quantified saponins-rich fraction was initially studied in maximal electroshock and pentylenetetrazol test at 1, 2 and 4 mg/kg; i.p. doses. Based on the results of initial anticonvulsant testing, different groups of mice were injected with vehicle or quantified saponins-rich fraction (4 mg/kg; i.p., 30 min prior to an injection of N-methyl-D-aspartic acid (100 mg/kg; s.c., bicuculline (5 mg/kg; i.p., strychnine hydrochloride (2 mg/kg; i.p., BAY k-8644 (37.5 µg; i.c.v., veratridine (500 µg/kg; i.p. and the convulsive episodes were studied. Treatment with the extract (1, 2 and 4 mg/kg showed significant protection in maximal electroshock and pentylenetetrazol-induced convulsion tests, in a dose-dependent manner. Moreover, quantified saponins-rich fraction at 4 mg/kg dose showed significant increase in latency to clonic convulsions, decrease in seizure severity and increase in average wave amplitude in bicuculline, BAY k-8644 and veratridine tests, respectively, as compared to vehicle control. However, SRF treatment failed to abolish N-methyl-D-aspartic acid and strychnine-induced convulsions, indicated by insignificant change in the appearance of turning behavior and onset of tonic extension, respectively, as compared to vehicle control. From the results of present study, it is concluded that quantified saponins-rich fraction suppress maximal electroshock, pentylenetetrazol, bicuculline, BAY k-8644 and veratridine-induced convulsions, indicating its GABAergic, Na+ and Ca2+ channel modulatory effects. Further it can be correlated that quantified saponins

  12. Endothelial epithelial sodium channel inhibition activates endothelial nitric oxide synthase via phosphoinositide 3-kinase/Akt in small-diameter mesenteric arteries.

    Science.gov (United States)

    Pérez, Francisco R; Venegas, Fabiola; González, Magdalena; Andrés, Sergio; Vallejos, Catalina; Riquelme, Gloria; Sierralta, Jimena; Michea, Luis

    2009-06-01

    Recent studies have shown that the epithelial sodium channel (ENaC) is expressed in vascular tissue. However, the role that ENaC may play in the responses to vasoconstrictors and NO production has yet to be addressed. In this study, the contractile responses of perfused pressurized small-diameter rat mesenteric arteries to phenylephrine and serotonin were reduced by ENaC blockade with amiloride (75.1+/-3.2% and 16.9+/-2.3% of control values, respectively; P<0.01) that was dose dependent (EC(50)=88.9+/-1.6 nmol/L). Incubation with benzamil, another ENaC blocker, had similar effects. alpha, beta, and gamma ENaC were identified in small-diameter rat mesenteric arteries using RT-PCR and Western blot with specific antibodies. In situ hybridization and immunohistochemistry localized ENaC expression to the tunica media and endothelium of small-diameter rat mesenteric arteries. Patch-clamp experiments demonstrated that primary cultures of mesenteric artery endothelial cells expressed amiloride-sensitive sodium currents. Mechanical ablation of the endothelium or inhibition of eNOS with N(omega)-nitro-L-arginine inhibited the reduction in contractility caused by ENaC blockers. ENaC inhibitors increased eNOS phosphorylation (Ser 1177) and Akt phosphorylation (Ser 473). The presence of the phosphoinositide 3-kinase inhibitor LY294002 blunted Akt phosphorylation and eNOS phosphorylation and the decrease in the response to phenylephrine caused by blockers of ENaC, indicating that the phosphoinositide 3-kinase/Akt pathway was activated after ENaC inhibition. Finally, we observed that the effects of blockers of ENaC were flow dependent and that the vasodilatory response to shear stress was enhanced by ENaC blockade. Our results identify a previously unappreciated role for ENaC as a negative modulator of eNOS and NO production in resistance arteries.

  13. Sodium-23 MRI of whole spine at 3 Tesla using a 5-channel receive-only phased-array and a whole-body transmit resonator

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    Malzacher, Matthias; Kalayciyan, Raffi; Konstandin, Simon; Schad, Lothar R. [Heidelberg Univ., Mannheim (Germany). Computer Assisted Clinical Medicine; Haneder, Stefan [Heidelberg Univ., Mannheim (Germany). Clinical Radiology and Nuclear Medicine; University Hospital of Cologne, Koeln (Germany). Dept. of Radiology

    2016-05-01

    Sodium magnetic resonance imaging ({sup 23}Na MRI) is a unique and non-invasive imaging technique which provides important information on cellular level about the tissue of the human body. Several applications for {sup 23}Na MRI were investigated with regard to the examination of the tissue viability and functionality for example in the brain, the heart or the breast. The {sup 23}Na MRI technique can also be integrated as a potential monitoring instrument after radiotherapy or chemotherapy. The main contribution in this work was the adaptation of {sup 23}Na MRI for spine imaging, which can provide essential information on the integrity of the intervertebral disks with respect to the early detection of disk degeneration. In this work, a transmit-only receive-only dual resonator system was designed and developed to cover the whole human spine using {sup 23}Na MRI and increase the receive sensitivity. The resonator system consisted of an already presented {sup 23}Na whole-body resonator and a newly developed 5-channel receive-only phased-array. The resonator system was first validated using bench top and phantom measurements. A threefold SNR improvement at the depth of the spine (∝7 cm) over the whole-body resonator was achieved using the spine array. {sup 23}Na MR measurements of the human spine using the transmit-only receive-only resonator system were performed on a healthy volunteer within an acquisition time of 10 minutes. A density adapted 3D radial sequence was chosen with 6 mm isotropic resolution, 49 ms repetition time and a short echo time of 540 μs. Furthermore, it was possible to quantify the tissue sodium concentration in the intervertebral discs in the lumbar region (120 ms repetition time) using this setup.

  14. Severe iatrogenic bradycardia related to the combined use of beta-blocking agents and sodium channel blockers

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    Kawabata M

    2015-02-01

    Full Text Available Mihoko Kawabata,1 Yasuhiro Yokoyama,1 Takeshi Sasaki,1 Susumu Tao,1 Kensuke Ihara,1 Yasuhiro Shirai,1 Tetsuo Sasano,2 Masahiko Goya,1 Tetsushi Furukawa,3 Mitsuaki Isobe,4 Kenzo Hirao1 1Heart Rhythm Center, Tokyo Medical and Dental University, Tokyo, Japan; 2Department of Biofunctional Informatics, Graduate School of Health Care Sciences, Tokyo Medical and Dental University, Tokyo, Japan; 3Department of Bio-informational Pharmacology, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan; 4Department of Cardiovascular Medicine, Tokyo Medical and Dental University, Tokyo, Japan Purpose: Drug-induced bradycardia is common during antiarrhythmic therapy; the major culprits are beta-blockers. However, whether other antiarrhythmic drugs are also a significant cause of this, alone or in combination with beta-blockers, is not well known. Methods: We retrospectively investigated the records of all patients hospitalized at our institution for drug-related bradycardia from the years 2004 to 2012. Patients with cardiac disease and electrolytic or hormonal abnormalities that could cause bradyarrhythmias were excluded. Results: Eight patients were identified (mean age, 79±5 years; range, 71–85 years; 6 women. Three patients were taking only beta-blockers (hereafter referred to as the BB group, while five patients were on both beta-blockers and Na channel blockers (hereafter referred to as the BB + Na group. Heart rates ranged from 20~49 beats/minute on arrival. The initial electrocardiogram showed sinus bradycardia (n=6 or sinus arrest with escape beats (n=2. QRS duration was 80–100 ms. The clinical presentation of the BB + Na group was considerably worse than that of the BB group, and included cardiogenic shock and heart failure. Four of the BB + Na patients had been on their medications for over 300 days. The BB group recovered solely with drug discontinuation, while 4 of the 5 patients in the BB + Na group needed additional

  15. Sustained expression of a neuron-specific isoform of the Taf1 gene in development stages and aging in mice

    International Nuclear Information System (INIS)

    Jambaldorj, Jamiyansuren; Makino, Satoshi; Munkhbat, Batmunkh; Tamiya, Gen

    2012-01-01

    Highlights: ► We identified the mouse homologue of neuron-specific TAF1 (N-Taf1). ► Taf1 mRNA was expressed in most tissues and cell lines. ► N-Taf1 mRNA was expressed in the brain and Neuroblastoma N2a cell lines. ► Taf1 and N-Taf1 showed different expression profile in development stage and aging. -- Abstract: TATA-box binding protein associated factor 1 (TAF1) protein is the largest and the essential component of the TFIID complex in the pathway of RNA polymerase II–mediated gene transcription, and it regulates transcription of a large number of genes related to cell division. The neuron-specific isoform of the TAF1 gene (N-TAF1), which we reported previously, may have an essential role in neurons through transcriptional regulation of many neuron-specific genes. In the present study, we cloned the full-length cDNA that encodes the mouse homologue of N-TAF1 (N-Taf1) protein. By carrying out of real time RT-PCR, we investigated the expression analysis of the N-Taf1 mRNA in mouse tissues and cell lines. As well as the human N-TAF1, the N-Taf1 showed limited expression in the brain and neuroblastoma, whereas Taf1 expressed elsewhere. Furthermore, in mouse embryo head or mouse brain, mRNA expression of TAF1 changes dramatically during development but N-Taf1 showed sustained expression. Our result suggests that the N-Taf1 gene has an important role in non-dividing neuronal cell rather than in cell division and proliferation during neurogenesis.

  16. Sustained expression of a neuron-specific isoform of the Taf1 gene in development stages and aging in mice

    Energy Technology Data Exchange (ETDEWEB)

    Jambaldorj, Jamiyansuren [Department of Pharmacology, Institute of Health Biosciences, Graduate School, The University of Tokushima, Tokushima 770-8503 (Japan); Advanced Molecular Epidemiology Research Institute, Yamagata University Faculty of Medicine, Yamagata 990-9585 (Japan); Central Scientific Research Laboratory, Institute of Medical Sciences, Ulaanbaatar (Mongolia); Makino, Satoshi, E-mail: smakino@genetix-h.com [Molecular Neuroscience Research Center, Shiga University of Medical Science, Otsu 520-2192 (Japan); Munkhbat, Batmunkh [Central Scientific Research Laboratory, Institute of Medical Sciences, Ulaanbaatar (Mongolia); Tamiya, Gen [Advanced Molecular Epidemiology Research Institute, Yamagata University Faculty of Medicine, Yamagata 990-9585 (Japan)

    2012-08-24

    Highlights: Black-Right-Pointing-Pointer We identified the mouse homologue of neuron-specific TAF1 (N-Taf1). Black-Right-Pointing-Pointer Taf1 mRNA was expressed in most tissues and cell lines. Black-Right-Pointing-Pointer N-Taf1 mRNA was expressed in the brain and Neuroblastoma N2a cell lines. Black-Right-Pointing-Pointer Taf1 and N-Taf1 showed different expression profile in development stage and aging. -- Abstract: TATA-box binding protein associated factor 1 (TAF1) protein is the largest and the essential component of the TFIID complex in the pathway of RNA polymerase II-mediated gene transcription, and it regulates transcription of a large number of genes related to cell division. The neuron-specific isoform of the TAF1 gene (N-TAF1), which we reported previously, may have an essential role in neurons through transcriptional regulation of many neuron-specific genes. In the present study, we cloned the full-length cDNA that encodes the mouse homologue of N-TAF1 (N-Taf1) protein. By carrying out of real time RT-PCR, we investigated the expression analysis of the N-Taf1 mRNA in mouse tissues and cell lines. As well as the human N-TAF1, the N-Taf1 showed limited expression in the brain and neuroblastoma, whereas Taf1 expressed elsewhere. Furthermore, in mouse embryo head or mouse brain, mRNA expression of TAF1 changes dramatically during development but N-Taf1 showed sustained expression. Our result suggests that the N-Taf1 gene has an important role in non-dividing neuronal cell rather than in cell division and proliferation during neurogenesis.

  17. Different role of TTX-sensitive voltage-gated sodium channel (NaV 1) subtypes in action potential initiation and conduction in vagal airway nociceptors.

    Science.gov (United States)

    Kollarik, M; Sun, H; Herbstsomer, R A; Ru, F; Kocmalova, M; Meeker, S N; Undem, B J

    2018-04-15

    The action potential initiation in the nerve terminals and its subsequent conduction along the axons of afferent nerves are not necessarily dependent on the same voltage-gated sodium channel (Na V 1) subunits. The action potential initiation in jugular C-fibres within airway tissues is not blocked by TTX; nonetheless, conduction of action potentials along the vagal axons of these nerves is often dependent on TTX-sensitive channels. This is not the case for nodose airway Aδ-fibres and C-fibres, where both action potential initiation and conduction is abolished by TTX or selective Na V 1.7 blockers. The difference between the initiation of action potentials within the airways vs. conduction along the axons should be considered when developing Na V 1 blocking drugs for topical application to the respiratory tract. The action potential (AP) initiation in the nerve terminals and its subsequent AP conduction along the axons do not necessarily depend on the same subtypes of voltage-gated sodium channels (Na V 1s). We evaluated the role of TTX-sensitive and TTX-resistant Na V 1s in vagal afferent nociceptor nerves derived from jugular and nodose ganglia innervating the respiratory system. Single cell RT-PCR was performed on vagal afferent neurons retrogradely labelled from the guinea pig trachea. Almost all of the jugular neurons expressed the TTX-sensitive channel Na V 1.7 along with TTX-resistant Na V 1.8 and Na V 1.9. Tracheal nodose neurons also expressed Na V 1.7 but, less frequently, Na V 1.8 and Na V 1.9. Na V 1.6 were expressed in ∼40% of the jugular and 25% of nodose tracheal neurons. Other Na V 1 α subunits were only rarely expressed. Single fibre recordings were made from the vagal nodose and jugular nerve fibres innervating the trachea or lung in the isolated perfused vagally-innervated preparations that allowed for selective drug delivery to the nerve terminal compartment (AP initiation) or to the desheathed vagus nerve (AP conduction). AP initiation in

  18. Therapeutic value of voltage-gated sodium channel inhibitors in breast, colorectal and prostate cancer: a systematic review

    Directory of Open Access Journals (Sweden)

    Fabiola eMartin

    2015-11-01

    Full Text Available Although survival rates of breast, colon and prostate cancers are improving, deaths from these tumors frequently occur due to metastasis. Voltage-gated Na+ channels (VGSCs are membrane proteins, which regulate membrane current and cellular migration during nervous system organogenesis. VGSCs are also expressed in fibroblasts, immune cells, glia and metastatic cancer cells. VGSCs regulate migration and invasion of breast, bowel and prostate cancer cells, suggesting that they may be novel anti-metastatic targets. We conducted a systematic review of clinical and preclinical studies testing the effects of VGSC-inhibiting drugs in cancer. 204 publications were identified, of which two human, two mouse and 20 in vitro publications were included. In the clinical studies, the effect of these drugs on survival and metastatic relapse is not clear. The 22 preclinical studies collectively suggest that several VGSC-inhibiting drugs inhibit cancer proliferation, migration and invasion. None of the human and only six of the preclinical studies directly investigated the effect of the drugs on VGSC activity. Studies were difficult to compare due to lack of standardized methodology and outcome measures. We conclude that the benefits of VGSC inhibitors require further investigation. Standardization of future studies and outcome measures should enable meaningful study comparisons.

  19. Slack channels expressed in sensory neurons control neuropathic pain in mice.

    Science.gov (United States)

    Lu, Ruirui; Bausch, Anne E; Kallenborn-Gerhardt, Wiebke; Stoetzer, Carsten; Debruin, Natasja; Ruth, Peter; Geisslinger, Gerd; Leffler, Andreas; Lukowski, Robert; Schmidtko, Achim

    2015-01-21

    Slack (Slo2.2) is a sodium-activated potassium channel that regulates neuronal firing activities and patterns. Previous studies identified Slack in sensory neurons, but its contribution to acute and chronic pain in vivo remains elusive. Here we generated global and sensory neuron-specific Slack mutant mice and analyzed their behavior in various animal models of pain. Global ablation of Slack led to increased hypersensitivity in models of neuropathic pain, whereas the behavior in models of inflammatory and acute nociceptive pain was normal. Neuropathic pain behaviors were also exaggerated after ablation of Slack selectively in sensory neurons. Notably, the Slack opener loxapine ameliorated persisting neuropathic pain behaviors. In conclusion, Slack selectively controls the sensory input in neuropathic pain states, suggesting that modulating its activity might represent a novel strategy for management of neuropathic pain. Copyright © 2015 the authors 0270-6474/15/351125-11$15.00/0.

  20. First detection of multiple knockdown resistance (kdr)-like mutations in voltage-gated sodium channel using three new genotyping methods in Anopheles sinensis from Guangxi Province, China.

    Science.gov (United States)

    Tan, Wei L; Li, Chun X; Wang, Zhong M; Liu, Mei D; Dong, Yan D; Feng, Xiang Y; Wu, Zhi M; Guo, Xiao X; Xing, Dan; Zhang, Ying M; Wang, Zhong C; Zhao, Tong Y

    2012-09-01

    To investigate knockdown resistance (kdr)-like mutations associated with pyrethroid resistance in Anopheles sinensis (Wiedemann, 1828), from Guangxi province, southwest China, a segment of a sodium channel gene was sequenced and genotyped using three new genotyping assays. Direct sequencing revealed the presence of TTG-to-TCG and TG-to-TTT mutations at allele position L1014, which led to L1014S and L1014F substitutions in a few individual and two novel substitutions of N1013S and L1014W in two DNA templates. A low frequency of the kdr allele mostly in the heterozygous state of L1014S and L1014F was observed in this mosquito population. In this study, the genotyping of An. sinensis using three polymerase chain reaction-based methods generated consistent results, which agreed with the results of DNA sequencing. In total, 52 mosquitoes were genotyped using a direct sequencing assay. The number of mosquitoes and their genotypes were as follows: L/L = 24, L/S = 19, L/F = 8, and F/W = 1. The allelic frequency of L1014, 1014S, and 1014F were 72, 18, and 9%, respectively.

  1. Soluble adenylyl cyclase in vascular endothelium: gene expression control of epithelial sodium channel-α, Na+/K+-ATPase-α/β, and mineralocorticoid receptor.

    Science.gov (United States)

    Schmitz, Boris; Nedele, Johanna; Guske, Katrin; Maase, Martina; Lenders, Malte; Schelleckes, Michael; Kusche-Vihrog, Kristina; Brand, Stefan-Martin; Brand, Eva

    2014-04-01

    The Ca(2+)- and bicarbonate-activated soluble adenylyl cyclase (sAC) has been identified recently as an important mediator of aldosterone signaling in the kidney. Nuclear sAC has been reported to stimulate cAMP response element-binding protein 1 phosphorylation via protein kinase A, suggesting an alternative cAMP pathway in the nucleus. In this study, we analyzed the sAC as a potential modulator of endothelial stiffness in the vascular endothelium. We determined the contribution of sAC to cAMP response element-mediated transcriptional activation in vascular endothelial cells and kidney collecting duct cells. Inhibition of sAC by the specific inhibitor KH7 significantly reduced cAMP response element-mediated promoter activity and affected cAMP response element-binding protein 1 phosphorylation. Furthermore, KH7 and anti-sAC small interfering RNA significantly decreased mRNA and protein levels of epithelial sodium channel-α and Na(+)/K(+)-ATPase-α. Using atomic force microscopy, a nano-technique that measures stiffness and deformability of living cells, we detected significant endothelial cell softening after sAC inhibition. Our results suggest that the sAC is a regulator of gene expression involved in aldosterone signaling and an important regulator of endothelial stiffness. Additional studies are warranted to investigate the protective action of sAC inhibitors in humans for potential clinical use.

  2. Frequency of V1016I and F1534C mutations in the voltage-gated sodium channel gene in Aedes aegypti in Venezuela.

    Science.gov (United States)

    Alvarez, Leslie C; Ponce, Gustavo; Saavedra-Rodriguez, Karla; Lopez, Beatriz; Flores, Adriana E

    2015-06-01

    The V1016I and F1534C mutations in the voltage-gated sodium channel gene have been associated with resistance to pyrethroids and DDT in Aedes aegypti mosquitoes. A study was carried out to determine the frequency of I1016 and C1534 by real-time PCR in five natural populations of Ae. aegypti in Venezuela during 2008, 2010 and 2012, as well as in a strain selected with 0.14 µg of deltamethrin for 15 generations. In natural populations, frequencies of I1016 varied between 0.01 and 0.37, and frequencies of C1534 between 0.35 and 1.0. In the Pampanito strain, the frequency of I1016 increased from 0.02 in F1 up to 0.5 in F15 and from 0.35 up to fixation for C1534 after selection with deltamethrin. The results showed that C1534 frequencies are higher than I1016 frequencies in natural populations of Ae. aegypti in Venezuela, and that deltamethrin selected the C1534 more rapidly than I1016. © 2014 Society of Chemical Industry.

  3. Species selective resistance of cardiac muscle voltage gated sodium channels: characterization of brevetoxin and ciguatoxin binding sites in rats and fish.

    Science.gov (United States)

    Dechraoui, Marie-Yasmine Bottein; Wacksman, Jeremy J; Ramsdell, John S

    2006-11-01

    Brevetoxins (PbTxs) and ciguatoxins (CTXs) are two suites of dinoflagellate derived marine polyether neurotoxins that target the voltage gated sodium channel (VGSC). PbTxs are commonly responsible for massive fish kills and unusual mortalities in marine mammals. CTXs, more often noted for human intoxication, are suspected causes of fish and marine mammal intoxication, although this has never been reported in the field. VGSCs, present in the membrane of all excitable cells including those found in skeletal muscle, nervous and heart tissues, are found as isoforms with differential expression within species and tissues. To investigate the tissue and species susceptibility to these biotoxins, we determined the relative affinity of PbTx-2 and -3 and P-CTX-1 to native VGSCs in the brain, heart, and skeletal muscle of rat and the marine teleost fish Centropristis striata by competitive binding in the presence of [(3)H]PbTx-3. No differences between rat and fish were observed in the binding of PbTxs and CTX to either brain or skeletal muscle. However, [(3)H]PbTx-3 showed substantial lower affinity to rat heart tissue while in the fish it bound with the same affinity to heart than to brain or skeletal muscle. These new insights into PbTxs and CTXs binding in fish and mammalian excitable tissues indicate a species related resistance of heart VGSC in the rat; yet, with comparable sensitivity between the species for brain and skeletal muscle.

  4. Increased cystic fibrosis transmembrane conductance regulators expression and decreased epithelial sodium channel alpha subunits expression in early abortion: findings from a mouse model and clinical cases of abortion.

    Directory of Open Access Journals (Sweden)

    Min Zhou

    Full Text Available The status of the maternal endometrium is vital in regulating humoral homeostasis and for ensuring embryo implantation. Cystic fibrosis transmembrane conductance regulators (CFTR and epithelial sodium channel alpha subunits (ENaC-α play an important role in female reproduction by maintaining humoral and cell homeostasis. However, it is not clear whether the expression levels of CFTR and ENaC-α in the decidual component during early pregnancy are related with early miscarriage. CBA×DBA/2 mouse mating has been widely accepted as a classical model of early miscarriage. The abortion rate associated with this mating was 33.33% in our study. The decidua of abortion-prone CBA female mice (DBA/2 mated had higher CFTR mRNA and protein expression and lower ENaC-α mRNA and protein expression, compared to normal pregnant CBA mice (BLAB/C mated. Furthermore, increased CFTR expression and decreased ENaC-α expression were observed in the uterine tissue from women with early miscarriage, as compared to those with successful pregnancy. In conclusion, increased CFTR expression and decreased ENaC-α expression in the decidua of early abortion may relate with failure of early pregnancy.

  5. Docking Simulation of the Binding Interactions of Saxitoxin Analogs Produced by the Marine Dinoflagellate Gymnodinium catenatum to the Voltage-Gated Sodium Channel Nav1.4

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    Lorena M. Durán-Riveroll

    2016-05-01

    Full Text Available Saxitoxin (STX and its analogs are paralytic alkaloid neurotoxins that block the voltage-gated sodium channel pore (Nav, impeding passage of Na+ ions into the intracellular space, and thereby preventing the action potential in the peripheral nervous system and skeletal muscle. The marine dinoflagellate Gymnodinium catenatum produces an array of such toxins, including the recently discovered benzoyl analogs, for which the mammalian toxicities are essentially unknown. We subjected STX and its analogs to a theoretical docking simulation based upon two alternative tri-dimensional models of the Nav1.4 to find a relationship between the binding properties and the known mammalian toxicity of selected STX analogs. We inferred hypothetical toxicities for the benzoyl analogs from the modeled values. We demonstrate that these toxins exhibit different binding modes with similar free binding energies and that these alternative binding modes are equally probable. We propose that the principal binding that governs ligand recognition is mediated by electrostatic interactions. Our simulation constitutes the first in silico modeling study on benzoyl-type paralytic toxins and provides an approach towards a better understanding of the mode of action of STX and its analogs.

  6. Docking Simulation of the Binding Interactions of Saxitoxin Analogs Produced by the Marine Dinoflagellate Gymnodinium catenatum to the Voltage-Gated Sodium Channel Nav1.4.

    Science.gov (United States)

    Durán-Riveroll, Lorena M; Cembella, Allan D; Band-Schmidt, Christine J; Bustillos-Guzmán, José J; Correa-Basurto, José

    2016-05-06

    Saxitoxin (STX) and its analogs are paralytic alkaloid neurotoxins that block the voltage-gated sodium channel pore (Nav), impeding passage of Na⁺ ions into the intracellular space, and thereby preventing the action potential in the peripheral nervous system and skeletal muscle. The marine dinoflagellate Gymnodinium catenatum produces an array of such toxins, including the recently discovered benzoyl analogs, for which the mammalian toxicities are essentially unknown. We subjected STX and its analogs to a theoretical docking simulation based upon two alternative tri-dimensional models of the Nav1.4 to find a relationship between the binding properties and the known mammalian toxicity of selected STX analogs. We inferred hypothetical toxicities for the benzoyl analogs from the modeled values. We demonstrate that these toxins exhibit different binding modes with similar free binding energies and that these alternative binding modes are equally probable. We propose that the principal binding that governs ligand recognition is mediated by electrostatic interactions. Our simulation constitutes the first in silico modeling study on benzoyl-type paralytic toxins and provides an approach towards a better understanding of the mode of action of STX and its analogs.

  7. Reduction of voltage gated sodium channel protein in DRG by vector mediated miRNA reduces pain in rats with painful diabetic neuropathy.

    Science.gov (United States)

    Chattopadhyay, Munmun; Zhou, Zhigang; Hao, Shuanglin; Mata, Marina; Fink, David J

    2012-03-22

    Painful neuropathy is a common complication of diabetes. Previous studies have identified significant increases in the amount of voltage gated sodium channel isoforms Na(V)1.7 and Na(V)1.3 protein in the dorsal root ganglia (DRG) of rats with streptozotocin (STZ)-induced diabetes. We found that gene transfer-mediated release of the inhibitory neurotransmitters enkephalin or gamma amino butyric acid (GABA) from DRG neurons in diabetic animals reduced pain-related behaviors coincident with a reduction in Na(V)1.7 protein levels in DRG in vivo. To further evaluate the role of Na(V)α subunit levels in DRG in the pathogenesis of pain in diabetic neuropathy, we constructed a non-replicating herpes simplex virus (HSV)-based vector expressing a microRNA (miRNA) against Na(V)α subunits. Subcutaneous inoculation of the miRNA-expressing HSV vector into the feet of diabetic rats to transduce DRG resulted in a reduction in Na(V)α subunit levels in DRG neurons, coincident with a reduction in cold allodynia, thermal hyperalgesia and mechanical hyperalgesia. These data support the role of increased Na(V)α protein in DRG in the pathogenesis of pain in diabetic neuropathy, and provide a proof-of-principle demonstration for the development of a novel therapy that could be used to treat intractable pain in patients with diabetic neuropathy.

  8. Effects of (−-Gallocatechin-3-Gallate on Tetrodotoxin-Resistant Voltage-Gated Sodium Channels in Rat Dorsal Root Ganglion Neurons

    Directory of Open Access Journals (Sweden)

    Jian-Min Jiang

    2013-05-01

    Full Text Available The (−-gallocatechin-3-gallate (GCG concentration in some tea beverages can account for as much as 50% of the total catechins. It has been shown that catechins have analgesic properties. Voltage-gated sodium channels (Nav mediate neuronal action potentials. Tetrodotoxin inhibits all Nav isoforms, but Nav1.8 and Nav1.9 are relatively tetrodotoxin-resistant compared to other isoforms and functionally linked to nociception. In this study, the effects of GCG on tetrodotoxin-resistant Na+ currents were investigated in rat primary cultures of dorsal root ganglion neurons via the whole-cell patch-clamp technique. We found that 1 μM GCG reduced the amplitudes of peak current density of tetrodotoxin-resistant Na+ currents significantly. Furthermore, the inhibition was accompanied by a depolarizing shift of the activation voltage and a hyperpolarizing shift of steady-state inactivation voltage. The percentage block of GCG (1 μM on tetrodotoxin-resistant Na+ current was 45.1% ± 1.1% in 10 min. In addition, GCG did not produce frequency-dependent block of tetrodotoxin-resistant Na+ currents at stimulation frequencies of 1 Hz, 2 Hz and 5 Hz. On the basis of these findings, we propose that GCG may be a potential analgesic agent.

  9. Osteoarthritis-dependent changes in antinociceptive action of Nav1.7 and Nav1.8 sodium channel blockers: An in vivo electrophysiological study in the rat.

    Science.gov (United States)

    Rahman, W; Dickenson, A H

    2015-06-04

    Voltage-gated sodium channel blockers are not traditionally recommended for osteoarthritis (OA) pain therapy, but given the large peripheral drive that follows OA development there is a rationale for their use. Using a rat model of monosodium iodoacetate (MIA)-induced OA we used in vivo electrophysiology to assess the effects of the Nav1.7- and Nav1.8-selective antagonists, ProTxII and A-803467 respectively, on the evoked activity of spinal dorsal horn neurons in response to electrical, mechanical and thermal stimuli applied to the peripheral receptive field. These studies allow examination of the roles of these channels in suprathreshold stimuli, not amenable to behavioral threshold measures. Spinal administration of ProTxII significantly reduced neuronal responses evoked by mechanical punctate (von Frey (vF) 8-60g) and noxious thermal (45 and 48°C) stimuli in MIA rats only. A-803467 significantly inhibited neuronal responses evoked by vF 8-60g and 48°C heat after spinal administration; significantly inhibited responses evoked by brush, vFs 26-60g and 40-48°C stimuli after systemic administration; significantly inhibited the electrically evoked Aδ-, C-fiber, post-discharge, Input and wind-up responses and the brush, vFs 8-60g and 45-48°C evoked neuronal responses after intra plantar injection in the MIA group. In comparison A-803467 effects in the sham group were minimal and included a reduction of the neuronal response evoked by vF 60g and 45°C heat stimulation after spinal administration, no effect after systemic administration and an inhibition of the evoked response to 45°C heat after intra plantar injection only. The observed selective inhibitory effect of ProTxII and A-803467 for the MIA-treated group suggests an increased role of Nav1.7 and 1.8 within nociceptive pathways in the arthritic condition, located at peripheral and central sites. These findings demonstrate the importance of, and add to, the mechanistic understanding of these channels in

  10. Biological Variation and Reference Change Value Data for Serum Neuron-Specific Enolase in a Turkish Population.

    Science.gov (United States)

    Matyar, Selcuk; Goruroglu Ozturk, Ozlem; Ziyanoglu Karacor, Esin; Yuzbasioglu Ariyurek, Sedefgul; Sahin, Gulhan; Kibar, Filiz; Yaman, Akgun; Inal, Tamer

    2016-11-01

    Neuron-specific enolase (NSE) is a recognized biomarker for the assessment of cerebral injury in neurological disorders. This study aims to report a definitive assessment of the biological variation (BV) components of this biomarker, including within-subject BV (CVI), between-subject BV (CVG), index of individuality (II), and reference change value (RCV), in a cohort of Turkish participants using an experimental protocol. Six blood specimens were collected from each of the 13 apparently healthy volunteers (seven women, six men; ranging in age from 23 to 36) on the same day, every 2 weeks for 2 months. Serum specimens were stored at -20°C until analysis. Neuron-specific enolase levels were evaluated in serum samples using an electrochemiluminescence (ECLIA) immunoassay kit with a Roche Cobas e 411 auto-analyser. ANOVA test was used to calculate the variations. The CVI and CVG for NSE were 21.5% and 28.8%, respectively. Analytical variation (CVA) was calculated as 10.2%. Additionally, II and RCV were calculated as 0.74 and 66% (95% confident interval, CI), respectively. As the performance index (PI) was found to be less than 2 (PI = 0.95), it is concluded that the NSE measurements have a desirable performance for analytical imprecision. Since the II was found to be less than 1 (II: 0.74), the reference values will be of little use. Thus, RCV would provide better information for deciding whether a significant change has occurred. © 2016 Wiley Periodicals, Inc.

  11. Biomarkers S100B and neuron-specific enolase predict outcome in hypothermia-treated encephalopathic newborns*.

    Science.gov (United States)

    Massaro, An N; Chang, Taeun; Baumgart, Stephen; McCarter, Robert; Nelson, Karin B; Glass, Penny

    2014-09-01

    To evaluate if serum S100B protein and neuron-specific enolase measured during therapeutic hypothermia are predictive of neurodevelopmental outcome at 15 months in children with neonatal encephalopathy. Prospective longitudinal cohort study. A level IV neonatal ICU in a freestanding children's hospital. Term newborns with moderate to severe neonatal encephalopathy referred for therapeutic hypothermia during the study period. Serum neuron-specific enolase and S100B were measured at 0, 12, 24, and 72 hours of hypothermia. Of the 83 infants enrolled, 15 (18%) died in the newborn period. Survivors were evaluated by the Bayley Scales of Infant Development-II at 15 months. Outcomes were assessed in 49 of 68 survivors (72%) at a mean age of 15.2 ± 2.7 months. Neurodevelopmental outcome was classified by Bayley Scales of Infant Development-II Mental Developmental Index and Psychomotor Developmental Index scores, reflecting cognitive and motor outcomes, respectively. Four-level outcome classifications were defined a priori: normal = Mental Developmental Index/Psychomotor Developmental Index within 1 SD (> 85), mild = Mental Developmental Index/Psychomotor Developmental Index less than 1 SD (70-85), moderate/severe = Mental Developmental Index/Psychomotor Developmental Index less than 2 SD (encephalopathy are associated with neurodevelopmental outcome at 15 months. These putative biomarkers of brain injury may help direct care during therapeutic hypothermia.

  12. Optogenetically enhanced axon regeneration: motor versus sensory neuron-specific stimulation.

    Science.gov (United States)

    Ward, Patricia J; Clanton, Scott L; English, Arthur W

    2018-02-01

    Brief neuronal activation in injured peripheral nerves is both necessary and sufficient to enhance motor axon regeneration, and this effect is specific to the activated motoneurons. It is less clear whether sensory neurons respond in a similar manner to neuronal activation following peripheral axotomy. Further, it is unknown to what extent enhancement of axon regeneration with increased neuronal activity relies on a reflexive interaction within the spinal circuitry. We used mouse genetics and optical tools to evaluate the precision and selectivity of system-specific neuronal activation to enhance axon regeneration in a mixed nerve. We evaluated sensory and motor axon regeneration in two different mouse models expressing the light-sensitive cation channel, channelrhodopsin (ChR2). We selectively activated either sensory or motor axons using light stimulation combined with transection and repair of the sciatic nerve. Regardless of genotype, the number of ChR2-positive neurons whose axons had regenerated successfully was greater following system-specific optical treatment, with no effect on the number of ChR2-negative neurons (whether motor or sensory neurons). We conclude that acute system-specific neuronal activation is sufficient to enhance both motor and sensory axon regeneration. This regeneration-enhancing effect is likely cell autonomous. © 2018 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  13. A new sodium channel {alpha}-subunit gene (Scn9a) from Schwann cells maps to the Scn1a, Scn2a, Scn3a cluster of mouse chromosome 2

    Energy Technology Data Exchange (ETDEWEB)

    Beckers, M.C.; Ernst, E.; Gros, P. [McGill Univ., Montreal (Canada)

    1996-08-15

    We have used a total of 27 AXB/BXA recombinant inbred mouse strains to determine the chromosomal location of a newly identified gene encoding an {alpha}-subunit isoform of the sodium channel from Schwann cells, Scn9a. Linkage analysis established that Scn9a mapped to the proximal segment of mouse chromosome 2. The segregation of restriction fragment length polymorphisms in 145 progeny from a Mus spretus x C57BL/6J backcross indicates that Scn9a is very tightly linked to Scn1a (gene encoding the type I sodium channel {alpha}-subunit of the brain) and forms part of a cluster of four Scna genes located on mouse chromosome 2. 17 refs., 1 fig., 3 tabs.

  14. Hydrogen sulfide prevents hydrogen peroxide-induced activation of epithelial sodium channel through a PTEN/PI(3,4,5P3 dependent pathway.

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    Jianing Zhang

    Full Text Available Sodium reabsorption through the epithelial sodium channel (ENaC at the distal segment of the kidney plays an important role in salt-sensitive hypertension. We reported previously that hydrogen peroxide (H2O2 stimulates ENaC in A6 distal nephron cells via elevation of phosphatidylinositol 3,4,5-trisphosphate (PI(3,4,5P3 in the apical membrane. Here we report that H2S can antagonize H2O2-induced activation of ENaC in A6 cells. Our cell-attached patch-clamp data show that ENaC open probability (PO was significantly increased by exogenous H2O2, which is consistent with our previous finding. The aberrant activation of ENaC induced by exogenous H2O2 was completely abolished by H2S (0.1 mM NaHS. Pre-treatment of A6 cells with H2S slightly decreased ENaC P(O; however, in these cells H2O2 failed to elevate ENaC PO . Confocal microscopy data show that application of exogenous H2O2 to A6 cells significantly increased intracellular reactive oxygen species (ROS level and induced accumulation of PI(3,4,5P3 in the apical compartment of the cell membrane. These effects of exogenous H2O2 on intracellular ROS levels and on apical PI(3,4,5P3 levels were almost completely abolished by treatment of A6 cells with H2S. In addition, H2S significantly inhibited H2O2-induced oxidative inactivation of the tumor suppressor phosphatase and tensin homolog (PTEN which is a negative regulator of PI(3,4,5P3. Moreover, BPV(pic, a specific inhibitor of PTEN, elevated PI(3,4,5P3 and ENaC activity in a manner similar to that of H2O2 in A6 cells. Our data show, for the first time, that H2S prevents H2O2-induced activation of ENaC through a PTEN-PI(3,4,5P3 dependent pathway.

  15. Identification of an alternative knockdown resistance (kdr)-like mutation, M918L, and a novel mutation, V1010A, in the Thrips tabaci voltage-gated sodium channel gene.

    Science.gov (United States)

    Wu, Meixiang; Gotoh, Hiroki; Waters, Timothy; Walsh, Douglas B; Lavine, Laura Corley

    2014-06-01

    Knockdown resistance (kdr) has been identified as a main mechanism against pyrethroid insecticides in many arthropod pests including in the onion thrips, Thrips tabaci. To characterize and identify pyrethroid-resistance in onion thrips in Washington state, we conducted insecticide bioassays and sequenced a region of the voltage gated sodium channel gene from several different T. tabaci populations. Field collected Thrips tabaci were found to have large variations in resistance to the pyrethroid insecticide lambda-cyhalothrin. We identified two single nucleotide substitutions in our analysis of a partial sequence of the T. tabaci voltage-gated sodium channel gene. One mutation resulted in the non-synonymous substitution of methionine with leucine (M918L), which is well known to be responsible for super knockdown resistance in some pest species. Another non-synonymous substitution, a valine (GTT) to alanine (GCT) replacement at amino acid 1010 (V1010A) was identified in our study and was associated with lambda-cyhalothrin resistance. We have characterized a known kdr mutation and identified a novel mutation in the voltage-gated sodium channel gene of Thrips tabaci associated with resistance to lambda-cyhalothrin. This gene region and these mutations are expected to be useful in the development of a diagnostic test to detect kdr resistance in many onion thrips populations. © 2013 Society of Chemical Industry.

  16. Differential state-dependent modification of rat Na{sub v}1.6 sodium channels expressed in human embryonic kidney (HEK293) cells by the pyrethroid insecticides tefluthrin and deltamethrin

    Energy Technology Data Exchange (ETDEWEB)

    He, Bingjun [College of Life Sciences, Nankai University, Tianjin 300071 (China); Soderlund, David M., E-mail: dms6@cornell.edu [Department of Entomology, Cornell University, New York State Agricultural Experiment Station, Geneva, NY 14456 (United States)

    2011-12-15

    We expressed rat Na{sub v}1.6 sodium channels in combination with the rat {beta}1 and {beta}2 auxiliary subunits in human embryonic kidney (HEK293) cells and evaluated the effects of the pyrethroid insecticides tefluthrin and deltamethrin on expressed sodium currents using the whole-cell patch clamp technique. Both pyrethroids produced concentration-dependent, resting modification of Na{sub v}1.6 channels, prolonging the kinetics of channel inactivation and deactivation to produce persistent 'late' currents during depolarization and tail currents following repolarization. Both pyrethroids also produced concentration dependent hyperpolarizing shifts in the voltage dependence of channel activation and steady-state inactivation. Maximal shifts in activation, determined from the voltage dependence of the pyrethroid-induced late and tail currents, were {approx} 25 mV for tefluthrin and {approx} 20 mV for deltamethrin. The highest attainable concentrations of these compounds also caused shifts of {approx} 5-10 mV in the voltage dependence of steady-state inactivation. In addition to their effects on the voltage dependence of inactivation, both compounds caused concentration-dependent increases in the fraction of sodium current that was resistant to inactivation following strong depolarizing prepulses. We assessed the use-dependent effects of tefluthrin and deltamethrin on Na{sub v}1.6 channels by determining the effect of trains of 1 to 100 5-ms depolarizing prepulses at frequencies of 20 or 66.7 Hz on the extent of channel modification. Repetitive depolarization at either frequency increased modification by deltamethrin by {approx} 2.3-fold but had no effect on modification by tefluthrin. Tefluthrin and deltamethrin were equally potent as modifiers of Na{sub v}1.6 channels in HEK293 cells using the conditions producing maximal modification as the basis for comparison. These findings show that the actions of tefluthrin and deltamethrin of Na{sub v}1.6 channels

  17. A quantitative and comparative study of the effects of a synthetic ciguatoxin CTX3C on the kinetic properties of voltage-dependent sodium channels

    Science.gov (United States)

    Yamaoka, Kaoru; Inoue, Masayuki; Miyahara, Hidemichi; Miyazaki, Keisuke; Hirama, Masahiro

    2004-01-01

    Ciguatoxins (CTXs) are known to bind to receptor site 5 of the voltage-dependent Na channel, but the toxin's physiological effects are poorly understood. In this study, we investigated the effects of a ciguatoxin congener (CTX3C) on three different Na-channel isoforms, rNav1.2, rNav1.4, and rNav1.5, which were transiently expressed in HEK293 cells. The toxin (1.0 μmol l−1) shifted the activation potential (V1/2 of activation curve) in the negative direction by 4–9 mV and increased the slope factor (k) from 8 mV to between 9 and 12 mV (indicative of decreased steepness of the activation curve), thereby resulting in a hyperpolarizing shift of the threshold potential by 30 mV for all Na channel isoforms. The toxin (1.0 μmol l−1) significantly accelerated the time-to-peak current from 0.62 to 0.52 ms in isoform rNav1.2. Higher doses of the toxin (3–10 μmol l−1) additionally decreased time-to-peak current in rNav1.4 and rNav1.5. A toxin effect on decay of INa at −20 mV was either absent or marginal even at relatively high doses of CTX3C. The toxin (1 μmol l−1) shifted the inactivation potential (V1/2 of inactivation curve) in the negative direction by 15–18 mV in all isoforms. INa maxima of the I–V curve (at −20 mV) were suppressed by application of 1.0 μmol l−1 CTX3C to a similar extent (80–85% of the control) in all the three isoforms. Higher doses of CTX3C up to 10 μmol l−1 further suppressed INa to 61–72% of the control. Recovery from slow inactivation induced by a depolarizing prepulse of intermediate duration (500 ms) was dramatically delayed in the presence of 1.0 μmol l−1 CTX3C, as time constants describing the monoexponential recovery were increased from 38±8 to 588±151 ms (n=5), 53±6 to 338±85 ms (n=4), and 23±3 to 232±117 ms (n=3) in rNav1.2, rNav1.4, and rNav1.5, respectively. CTX3C exerted multimodal effects on sodium channels, with simultaneous stimulatory and inhibitory aspects, probably due to the large

  18. Role of Transient Receptor Potential Ankyrin 1 Ion Channel and Somatostatin sst4 Receptor in the Antinociceptive and Anti-inflammatory Effects of Sodium Polysulfide and Dimethyl Trisulfide

    Directory of Open Access Journals (Sweden)

    István Z. Bátai

    2018-02-01

    Full Text Available Transient receptor potential ankyrin 1 (TRPA1 non-selective ligand-gated cation channels are mostly expressed in primary sensory neurons. Polysulfides (POLYs are Janus-faced substances interacting with numerous target proteins and associated with both protective and detrimental processes. Activation of TRPA1 in sensory neurons, consequent somatostatin (SOM liberation and action on sst4 receptors have recently emerged as mediators of the antinociceptive effect of organic trisulfide dimethyl trisulfide (DMTS. In the frame of the present study, we set out to compare the participation of this mechanism in antinociceptive and anti-inflammatory effects of inorganic sodium POLY and DMTS in carrageenan-evoked hind-paw inflammation. Inflammation of murine hind paws was induced by intraplantar injection of carrageenan (3% in 30 µL saline. Animals were treated intraperitoneally with POLY (17 µmol/kg or DMTS (250 µmol/kg or their respective vehicles 30 min prior paw challenge and six times afterward every 60 min. Mechanical pain threshold and swelling of the paws were measured by dynamic plantar aesthesiometry and plethysmometry at 2, 4, and 6 h after initiation of inflammation. Myeloperoxidase (MPO activity in the hind paws were detected 6 h after challenge by luminescent imaging. Mice genetically lacking TRPA1 ion channels, sst4 receptors and their wild-type counterparts were used to examine the participation of these proteins in POLY and DMTS effects. POLY counteracted carrageenan-evoked mechanical hyperalgesia in a TRPA1 and sst4 receptor-dependent manner. POLY did not influence paw swelling and MPO activity. DMTS ameliorated all examined inflammatory parameters. Mitigation of mechanical hyperalgesia and paw swelling by DMTS were mediated through sst4 receptors. These effects were present in TRPA1 knockout animals, too. DMTS inhibited MPO activity with no participation of the sensory neuron–SOM axis. While antinociceptive effects of

  19. Co-occurrence of point mutations in the voltage-gated sodium channel of pyrethroid-resistant Aedes aegypti populations in Myanmar.

    Science.gov (United States)

    Kawada, Hitoshi; Oo, Sai Zaw Min; Thaung, Sein; Kawashima, Emiko; Maung, Yan Naung Maung; Thu, Hlaing Myat; Thant, Kyaw Zin; Minakawa, Noboru

    2014-01-01

    Single amino acid substitutions in the voltage-gated sodium channel associated with pyrethroid resistance constitute one of the main causative factors of knockdown resistance in insects. The kdr gene has been observed in several mosquito species; however, point mutations in the para gene of Aedes aegypti populations in Myanmar have not been fully characterized. The aim of the present study was to determine the types and frequencies of mutations in the para gene of Aedes aegypti collected from used tires in Yangon City, Myanmar. We determined high pyrethroid resistance in Aedes aegypti larvae at all collection sites in Yangon City, by using a simplified knockdown bioassay. We showed that V1016G and S989P mutations were widely distributed, with high frequencies (84.4% and 78.8%, respectively). By contrast, we were unable to detect I1011M (or I1011V) or L1014F mutations. F1534C mutations were also widely distributed, but with a lower frequency than the V1016G mutation (21.2%). High percentage of co-occurrence of the homozygous V1016G/S989P mutations was detected (65.7%). Additionally, co-occurrence of homozygous V1016G/F1534C mutations (2.9%) and homozygous V1016G/F1534C/S989P mutations (0.98%) were detected in the present study. Pyrethroid insecticides were first used for malaria control in 1992, and have since been constantly used in Myanmar. This intensive use may explain the strong selection pressure toward Aedes aegypti, because this mosquito is generally a domestic and endophagic species with a preference for indoor breeding. Extensive use of DDT for malaria control before the use of this chemical was banned may also explain the development of pyrethroid resistance in Aedes aegypti.

  20. Voltage-sensitive sodium channel mutations S989P + V1016G in Aedes aegypti confer variable resistance to pyrethroids, DDT and oxadiazines.

    Science.gov (United States)

    Smith, Letícia B; Kasai, Shinji; Scott, Jeffrey G

    2018-03-01

    Aedes aegypti is a vector of several important human pathogens. Control efforts rely primarily on pyrethroid insecticides for adult mosquito control, especially during disease outbreaks. A. aegypti has developed resistance nearly everywhere it occurs and insecticides are used. An important mechanism of resistance is due to mutations in the voltage-sensitive sodium channel (Vssc) gene. Two mutations, in particular, S989P + V1016G, commonly occur together in parts of Asia. We have created a strain (KDR:ROCK) that contains the Vssc mutations S989P + V1016G as the only mechanism of pyrethroid resistance within the genetic background of Rockefeller (ROCK), a susceptible lab strain. We created KDR:ROCK by crossing the pyrethroid-resistant strain Singapore with ROCK followed by four backcrosses with ROCK and Vssc S989P + V1016G genotype selections. We determined the levels of resistance conferred to 17 structurally diverse pyrethroids, the organochloride DDT, and oxadiazines (VSSC blockers) indoxacarb (proinsecticide) and DCJW (the active metabolite of indoxacarb). Levels of resistance to the pyrethroids were variable, ranging from 21- to 107-fold, but no clear pattern between resistance and chemical structure was observed. Resistance is inherited as an incompletely recessive trait. KDR:ROCK had a > 2000-fold resistance to DDT, 37.5-fold cross-resistance to indoxacarb and 13.4-fold cross-resistance to DCJW. Etofenprox (and DDT) should be avoided in areas where Vssc mutations S989P + V1016G exist at high frequencies. We found that pyrethroid structure cannot be used to predict the level of resistance conferred by kdr. These results provide useful information for resistance management and for better understanding pyrethroid interactions with VSSC. © 2017 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. © 2017 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of

  1. A novel amino acid substitution in a voltage-gated sodium channel is associated with knockdown resistance to permethrin in Aedes aegypti.

    Science.gov (United States)

    Chang, Cheng; Shen, Wen-Kai; Wang, Tzu-Ting; Lin, Ying-Hsi; Hsu, Err-Lieh; Dai, Shu-Mei

    2009-04-01

    To identify pertinent mutations associated with knockdown resistance to permethrin, the entire coding sequence of the voltage-gated sodium channel gene Aa-para was sequenced and analyzed from a Per-R strain with 190-fold resistance to permethrin and two susceptible strains of Aedes aegypti. The longest transcript, a 6441bp open reading frame, encodes 2147 amino acid residues with an estimated molecular mass of 241kDa. A total of 33 exons were found in the Aa-para gene over 293kb of genomic DNA. Three previously unreported optional exons were identified. The first two exons, m and n, were located within the intracellular domain I/II, and the third, f', was found within the II/III linkers. The two mutually exclusive exons, d and l, were the only alternative exons in all the cDNA clones sequenced in this study. The most distinct finding was a novel amino acid substitution mutation, D1794Y, located within the extracellular linker between IVS5 and IVS6, which is concurrent with the known V1023G mutation in Aa-para of the Per-R strain. The high frequency and coexistence of the two mutations in the Per-R strain suggest that they might exert a synergistic effect to provide the knockdown resistance to permethrin. Furthermore, both cDNA and genomic DNA data from the same individual mosquitoes have demonstrated that RNA editing was not involved in amino acid substitutions of the Per-R strain.

  2. Polymorphism of intron-1 in the voltage-gated sodium channel gene of Anopheles gambiae s.s. populations from Cameroon with emphasis on insecticide knockdown resistance mutations.

    Science.gov (United States)

    Etang, Josiane; Vicente, Jose L; Nwane, Philippe; Chouaibou, Mouhamadou; Morlais, Isabelle; Do Rosario, Virgilio E; Simard, Frederic; Awono-Ambene, Parfait; Toto, Jean Claude; Pinto, Joao

    2009-07-01

    Sequence variation at the intron-1 of the voltage-gated sodium channel gene in Anopheles gambiae M- and S-forms from Cameroon was assessed to explore the number of mutational events originating knockdown resistance (kdr) alleles. Mosquitoes were sampled between December 2005 and June 2006 from three geographical areas: (i) Magba in the western region; (ii) Loum, Tiko, Douala, Kribi, and Campo along the Atlantic coast; and (iii) Bertoua, in the eastern continental plateau. Both 1014S and 1014F kdr alleles were found in the S-form with overall frequencies of 14% and 42% respectively. Only the 1014F allele was found in the M-form at lower frequency (11%). Analysis of a 455 bp region of intron-1 upstream the kdr locus revealed four independent mutation events originating kdr alleles, here named MS1 -1014F, S1-1014S and S2-1014S kdr-intron-1 haplotypes in S-form and MS3-1014F kdr-intron-1 haplotype in the M-form. Furthermore, there was evidence for mutual introgression of kdr 1014F allele between the two molecular forms, MS1 and MS3 being widely shared by them. Although no M/S hybrid was observed in analysed samples, this wide distribution of haplotypes MS1 and MS3 suggests inter-form hybridizing at significant level and emphasizes the rapid diffusion of the kdr alleles in Africa. The mosaic of genetic events found in Cameroon is representative of the situation in the West-Central African region and highlights the importance of evaluating the spatial and temporal evolution of kdr alleles for a better management of insecticide resistance.

  3. Development of a Rapid Throughput Assay for Identification of hNav1.7 Antagonist Using Unique Efficacious Sodium Channel Agonist, Antillatoxin

    Directory of Open Access Journals (Sweden)

    Fang Zhao

    2016-02-01

    Full Text Available Voltage-gated sodium channels (VGSCs are responsible for the generation of the action potential. Among nine classified VGSC subtypes (Nav1.1–Nav1.9, Nav1.7 is primarily expressed in the sensory neurons, contributing to the nociception transmission. Therefore Nav1.7 becomes a promising target for analgesic drug development. In this study, we compared the influence of an array of VGSC agonists including veratridine, BmK NT1, brevetoxin-2, deltamethrin and antillatoxin (ATX on membrane depolarization which was detected by Fluorescence Imaging Plate Reader (FLIPR membrane potential (FMP blue dye. In HEK-293 cells heterologously expressing hNav1.7 α-subunit, ATX produced a robust membrane depolarization with an EC50 value of 7.8 ± 2.9 nM whereas veratridine, BmK NT1, and deltamethrin produced marginal response. Brevetoxin-2 was without effect on membrane potential change. The ATX response was completely inhibited by tetrodotoxin suggesting that the ATX response was solely derived from hNav1.7 activation, which was consistent with the results where ATX produced a negligible response in null HEK-293 cells. Six VGSC antagonists including lidocaine, lamotrigine, phenytoin, carbamazepine, riluzole, and 2-amino-6-trifluoromethylthiobenzothiazole all concentration-dependently inhibited ATX response with IC50 values comparable to that reported from patch-clamp experiments. Considered together, we demonstrate that ATX is a unique efficacious hNav1.7 activator which offers a useful probe to develop a rapid throughput screening assay to identify hNav1.7 antagonists.

  4. Development of a Rapid Throughput Assay for Identification of hNav1.7 Antagonist Using Unique Efficacious Sodium Channel Agonist, Antillatoxin.

    Science.gov (United States)

    Zhao, Fang; Li, Xichun; Jin, Liang; Zhang, Fan; Inoue, Masayuki; Yu, Boyang; Cao, Zhengyu

    2016-02-16

    Voltage-gated sodium channels (VGSCs) are responsible for the generation of the action potential. Among nine classified VGSC subtypes (Nav1.1-Nav1.9), Nav1.7 is primarily expressed in the sensory neurons, contributing to the nociception transmission. Therefore Nav1.7 becomes a promising target for analgesic drug development. In this study, we compared the influence of an array of VGSC agonists including veratridine, BmK NT1, brevetoxin-2, deltamethrin and antillatoxin (ATX) on membrane depolarization which was detected by Fluorescence Imaging Plate Reader (FLIPR) membrane potential (FMP) blue dye. In HEK-293 cells heterologously expressing hNav1.7 α-subunit, ATX produced a robust membrane depolarization with an EC50 value of 7.8 ± 2.9 nM whereas veratridine, BmK NT1, and deltamethrin produced marginal response. Brevetoxin-2 was without effect on membrane potential change. The ATX response was completely inhibited by tetrodotoxin suggesting that the ATX response was solely derived from hNav1.7 activation, which was consistent with the results where ATX produced a negligible response in null HEK-293 cells. Six VGSC antagonists including lidocaine, lamotrigine, phenytoin, carbamazepine, riluzole, and 2-amino-6-trifluoromethylthiobenzothiazole all concentration-dependently inhibited ATX response with IC50 values comparable to that reported from patch-clamp experiments. Considered together, we demonstrate that ATX is a unique efficacious hNav1.7 activator which offers a useful probe to develop a rapid throughput screening assay to identify hNav1.7 antagonists.

  5. Co-occurrence of Point Mutations in the Voltage-Gated Sodium Channel of Pyrethroid-Resistant Aedes aegypti Populations in Myanmar

    Science.gov (United States)

    Kawada, Hitoshi; Oo, Sai Zaw Min; Thaung, Sein; Kawashima, Emiko; Maung, Yan Naung Maung; Thu, Hlaing Myat; Thant, Kyaw Zin; Minakawa, Noboru

    2014-01-01

    Background Single amino acid substitutions in the voltage-gated sodium channel associated with pyrethroid resistance constitute one of the main causative factors of knockdown resistance in insects. The kdr gene has been observed in several mosquito species; however, point mutations in the para gene of Aedes aegypti populations in Myanmar have not been fully characterized. The aim of the present study was to determine the types and frequencies of mutations in the para gene of Aedes aegypti collected from used tires in Yangon City, Myanmar. Methodology/Principal Findings We determined high pyrethroid resistance in Aedes aegypti larvae at all collection sites in Yangon City, by using a simplified knockdown bioassay. We showed that V1016G and S989P mutations were widely distributed, with high frequencies (84.4% and 78.8%, respectively). By contrast, we were unable to detect I1011M (or I1011V) or L1014F mutations. F1534C mutations were also widely distributed, but with a lower frequency than the V1016G mutation (21.2%). High percentage of co-occurrence of the homozygous V1016G/S989P mutations was detected (65.7%). Additionally, co-occurrence of homozygous V1016G/F1534C mutations (2.9%) and homozygous V1016G/F1534C/S989P mutations (0.98%) were detected in the present study. Conclusions/Significance Pyrethroid insecticides were first used for malaria control in 1992, and have since been constantly used in Myanmar. This intensive use may explain the strong selection pressure toward Aedes aegypti, because this mosquito is generally a domestic and endophagic species with a preference for indoor breeding. Extensive use of DDT for malaria control before the use of this chemical was banned may also explain the development of pyrethroid resistance in Aedes aegypti. PMID:25077956

  6. Discovery of Point Mutations in the Voltage-Gated Sodium Channel from African Aedes aegypti Populations: Potential Phylogenetic Reasons for Gene Introgression

    Science.gov (United States)

    Muranami, Yuto; Kawashima, Emiko; Osei, Joseph H. N.; Sakyi, Kojo Yirenkyi; Dadzie, Samuel; de Souza, Dziedzom K.; Appawu, Maxwell; Ohta, Nobuo; Minakawa, Noboru

    2016-01-01

    Background Yellow fever is endemic in some countries in Africa, and Aedes aegpyti is one of the most important vectors implicated in the outbreak. The mapping of the nation-wide distribution and the detection of insecticide resistance of vector mosquitoes will provide the beneficial information for forecasting of dengue and yellow fever outbreaks and effective control measures. Methodology/Principal Findings High resistance to DDT was observed in all mosquito colonies collected in Ghana. The resistance and the possible existence of resistance or tolerance to permethrin were suspected in some colonies. High frequencies of point mutations at the voltage-gated sodium channel (F1534C) and one heterozygote of the other mutation (V1016I) were detected, and this is the first detection on the African continent. The frequency of F1534C allele and the ratio of F1534C homozygotes in Ae. aegypti aegypti (Aaa) were significantly higher than those in Ae. aegypti formosus (Aaf). We could detect the two types of introns between exon 20 and 21, and the F1534C mutations were strongly linked with one type of intron, which was commonly found in South East Asian and South and Central American countries, suggesting the possibility that this mutation was introduced from other continents or convergently selected after the introgression of Aaa genes from the above area. Conclusions/Significance The worldwide eradication programs in 1940s and 1950s might have caused high selection pressure on the mosquito populations and expanded the distribution of insecticide-resistant Ae. aegypti populations. Selection of the F1534C point mutation could be hypothesized to have taken place during this period. The selection of the resistant population of Ae. aegypti with the point mutation of F1534C, and the worldwide transportation of vector mosquitoes in accordance with human activity such as trading of used tires, might result in the widespread distribution of F1534C point mutation in tropical countries

  7. Sodium Channel Voltage-Gated Beta 2 Plays a Vital Role in Brain Aging Associated with Synaptic Plasticity and Expression of COX5A and FGF-2.

    Science.gov (United States)

    XiYang, Yan-Bin; Wang, You-Cui; Zhao, Ya; Ru, Jin; Lu, Bing-Tuan; Zhang, Yue-Ning; Wang, Nai-Chao; Hu, Wei-Yan; Liu, Jia; Yang, Jin-Wei; Wang, Zhao-Jun; Hao, Chun-Guang; Feng, Zhong-Tang; Xiao, Zhi-Cheng; Dong, Wei; Quan, Xiong-Zhi; Zhang, Lian-Feng; Wang, Ting-Hua

    2016-03-01

    The role of sodium channel voltage-gated beta 2 (SCN2B) in brain aging is largely unknown. The present study was therefore designed to determine the role of SCN2B in brain aging by using the senescence-accelerated mice prone 8 (SAMP8), a brain senescence-accelerated animal model, together with the SCN2B transgenic mice. The results showed that SAMP8 exhibited impaired learning and memory functions, assessed by the Morris water maze test, as early as 8 months of age. The messenger RNA (mRNA) and protein expressions of SCN2B were also upregulated in the prefrontal cortex at this age. Treatment with traditional Chinese anti-aging medicine Xueshuangtong (Panax notoginseng saponins, PNS) significantly reversed the SCN2B expressions in the prefrontal cortex, resulting in improved learning and memory. Moreover, SCN2B knockdown transgenic mice were generated and bred to determine the roles of SCN2B in brain senescence. A reduction in the SCN2B level by 60.68% resulted in improvement in the hippocampus-dependent spatial recognition memory and long-term potential (LTP) slope of field excitatory postsynaptic potential (fEPSP), followed by an upregulation of COX5A mRNA levels and downregulation of fibroblast growth factor-2 (FGF-2) mRNA expression. Together, the present findings indicated that SCN2B could play an important role in the aging-related cognitive deterioration, which is associated with the regulations of COX5A and FGF-2. These findings could provide the potential strategy of candidate target to develop antisenescence drugs for the treatment of brain aging.

  8. High salt loading induces urinary storage dysfunction via upregulation of epithelial sodium channel alpha in the bladder epithelium in Dahl salt-sensitive rats

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    Seiji Yamamoto

    2017-11-01

    Full Text Available We aimed to investigate whether high salt intake affects bladder function via epithelial sodium channel (ENaC by using Dahl salt-resistant (DR and salt-sensitive (DS rats. Bladder weight of DR + high-salt diet (HS, 8% NaCl and DS + HS groups were significantly higher than those of DR + normal-salt diet (NS, 0.3% NaCl and DS + NS groups after one week treatment. We thereafter used only DR + HS and DS + HS group. Systolic and diastolic blood pressures were significantly higher in DS + HS group than in DR + HS group after the treatment period. Cystometrogram showed the intercontraction intervals (ICI were significantly shorter in DS + HS group than in DR + HS group during infusion of saline. Subsequent infusion of amiloride significantly prolonged ICI in DS + HS group, while no intra-group difference in ICI was observed in DR + HS group. No intra- or inter-group differences in maximum intravesical pressure were observed. Protein expression levels of ENaCα in the bladder were significantly higher in DS + HS group than in DR + HS group. ENaCα protein was localized at bladder epithelium in both groups. In conclusion, high salt intake is considered to cause urinary storage dysfunction via upregulation of ENaC in the bladder epithelium with salt-sensitive hypertension, suggesting that ENaC might be a candidate for therapeutic target for urinary storage dysfunction.

  9. Novel cytochrome P450 (CYP6D1) and voltage sensitive sodium channel (Vssc) alleles of the house fly (Musca domestica) and their roles in pyrethroid resistance.

    Science.gov (United States)

    Pan, Jing; Yang, Chan; Liu, Yan; Gao, Qi; Li, Mei; Qiu, Xinghui

    2018-04-01

    The house fly Musca domestica is an important disease vector. Point mutation-mediated target-site insensitivity of the voltage sensitive sodium channel (VSSC) and increased detoxification mediated by cytochrome P450 (CYP6D1) overexpression have been characterized as two major mechanisms of pyrethroid resistance. In this study, genetic mutations in the Vssc and CYP6D1 genes and their contribution to pyrethroid resistance were investigated. Twelve lines of house flies homozygous for four genotypes were established. House flies carrying the VSSC 1014F mutation and overexpressing CYP6D1 had higher resistance to pyrethroids than those carrying 1014F alone. The presence of the 15-bp insert in the promoter region of the CYP6D1 gene did not necessarily result in a significant increase in CYP6D1 mRNA and pyrethroid resistance levels. A novel Vssc allele carrying two mutations (G1924D and G2004S) in combination with the classic 1014F and a novel CYP6D1 allele that is very similar to CYP6D1v1 were identified in Chinese house flies. This work demonstrates the effect of genetic mutations in CYP6D1 and Vssc on the susceptibility of house flies to pyrethroids, and verifies that 15-bp insert-containing CYP6D1 alleles have a single origin. These findings offer insights into the evolution of insecticide resistance and have implications for house fly control. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  10. The Deletion of Endothelial Sodium Channel α (αENaC Impairs Endothelium-Dependent Vasodilation and Endothelial Barrier Integrity in Endotoxemia in Vivo

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    Magdalena Sternak

    2018-04-01

    Full Text Available The role of epithelial sodium channel (ENaC activity in the regulation of endothelial function is not clear. Here, we analyze the role of ENaC in the regulation of endothelium-dependent vasodilation and endothelial permeability in vivo in mice with conditional αENaC subunit gene inactivation in the endothelium (endo-αENaCKO mice using unique MRI-based analysis of acetylcholine-, flow-mediated dilation and vascular permeability. Mice were challenged or not with lipopolysaccharide (LPS, from Salmonella typhosa, 10 mg/kg, i.p.. In addition, changes in vascular permeability in ex vivo organs were analyzed by Evans Blue assay, while changes in vascular permeability in perfused mesenteric artery were determined by a FITC-dextran-based assay. In basal conditions, Ach-induced response was completely lost, flow-induced vasodilation was inhibited approximately by half but endothelial permeability was not changed in endo-αENaCKO vs. control mice. In LPS-treated mice, both Ach- and flow-induced vasodilation was more severely impaired in endo-αENaCKO vs. control mice. There was also a dramatic increase in permeability in lungs, brain and isolated vessels as evidenced by in vivo and ex vivo analysis in endotoxemic endo-αENaCKO vs. control mice. The impaired endothelial function in endotoxemia in endo-αENaCKO was associated with a decrease of lectin and CD31 endothelial staining in the lung as compared with control mice. In conclusion, the activity of endothelial ENaC in vivo contributes to endothelial-dependent vasodilation in the physiological conditions and the preservation of endothelial barrier integrity in endotoxemia.

  11. Recapitulation of spinal motor neuron-specific disease phenotypes in a human cell model of spinal muscular atrophy

    Institute of Scientific and Technical Information of China (English)

    Zhi-Bo Wang; Xiaoqing Zhang; Xue-Jun Li

    2013-01-01

    Establishing human cell models of spinal muscular atrophy (SMA) to mimic motor neuron-specific phenotypes holds the key to understanding the pathogenesis of this devastating disease.Here,we developed a closely representative cell model of SMA by knocking down the disease-determining gene,survival motor neuron (SMN),in human embryonic stem cells (hESCs).Our study with this cell model demonstrated that knocking down of SMN does not interfere with neural induction or the initial specification of spinal motor neurons.Notably,the axonal outgrowth of spinal motor neurons was significantly impaired and these disease-mimicking neurons subsequently degenerated.Furthermore,these disease phenotypes were caused by SMN-full length (SMN-FL) but not SMN-A7 (lacking exon 7)knockdown,and were specific to spinal motor neurons.Restoring the expression of SMN-FL completely ameliorated all of the disease phenotypes,including specific axonal defects and motor neuron loss.Finally,knockdown of SMNFL led to excessive mitochondrial oxidative stress in human motor neuron progenitors.The involvement of oxidative stress in the degeneration of spinal motor neurons in the SMA cell model was further confirmed by the administration of N-acetylcysteine,a potent antioxidant,which prevented disease-related apoptosis and subsequent motor neuron death.Thus,we report here the successful establishment of an hESC-based SMA model,which exhibits disease gene isoform specificity,cell type specificity,and phenotype reversibility.Our model provides a unique paradigm for studying how motor neurons specifically degenerate and highlights the potential importance of antioxidants for the treatment of SMA.

  12. Identification of mutations associated with pyrethroid resistance in the voltage-gated sodium channel of the tomato leaf miner (Tuta absoluta).

    Science.gov (United States)

    Haddi, Khalid; Berger, Madeleine; Bielza, Pablo; Cifuentes, Dina; Field, Linda M; Gorman, Kevin; Rapisarda, Carmelo; Williamson, Martin S; Bass, Chris

    2012-07-01

    The tomato leaf miner, Tuta absoluta (Lepidoptera) is a significant pest of tomatoes that has undergone a rapid expansion in its range during the past six years and is now present across Europe, North Africa and parts of Asia. One of the main means of controlling this pest is through the use of chemical insecticides. In the current study insecticide bioassays were used to determine the susceptibility of five T. absoluta strains established from field collections from Europe and Brazil to pyrethroids. High levels of resistance to λ cyhalothrin and tau fluvalinate were observed in all five strains tested. To investigate whether pyrethroid resistance was mediated by mutation of the para-type sodium channel in T. absoluta the IIS4-IIS6 region of the para gene, which contains many of the mutation sites previously shown to confer knock down (kdr)-type resistance to pyrethroids across a range of different arthropod species, was cloned and sequenced. This revealed that three kdr/super-kdr-type mutations (M918T, T929I and L1014F), were present at high frequencies within all five resistant strains at known resistance 'hot-spots'. This is the first description of these mutations together in any insect population. High-throughput DNA-based diagnostic assays were developed and used to assess the prevalence of these mutations in 27 field strains from 12 countries. Overall mutant allele frequencies were high (L1014F 0.98, M918T 0.35, T929I 0.60) and remarkably no individual was observed that did not carry kdr in combination with either M918T or T929I. The presence of these mutations at high frequency in T. absoluta populations across much of its range suggests pyrethroids are likely to be ineffective for control and supports the idea that the rapid expansion of this species over the last six years may be in part mediated by the resistance of this pest to chemical insecticides. Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.

  13. Knockdown resistance (kdr)-like mutations in the voltage-gated sodium channel of a malaria vector Anopheles stephensi and PCR assays for their detection.

    Science.gov (United States)

    Singh, Om P; Dykes, Cherry L; Lather, Manila; Agrawal, Om P; Adak, Tridibes

    2011-03-14

    Knockdown resistance (kdr) in insects, resulting from mutation(s) in the voltage-gated sodium channel (vgsc) gene is one of the mechanisms of resistance against DDT and pyrethroid-group of insecticides. The most common mutation(s) associated with knockdown resistance in insects, including anophelines, has been reported to be present at residue Leu1014 in the IIS6 transmembrane segment of the vgsc gene. This study reports the presence of two alternative kdr-like mutations, L1014S and L1014F, at this residue in a major malaria vector Anopheles stephensi and describes new PCR assays for their detection. Part of the vgsc (IIS4-S5 linker-to-IIS6 transmembrane segment) of An. stephensi collected from Alwar (Rajasthan, India) was PCR-amplified from genomic DNA, sequenced and analysed for the presence of deduced amino acid substitution(s). Analysis of DNA sequences revealed the presence of two alternative non-synonymous point mutations at L1014 residue in the IIS6 transmembrane segment of vgsc, i.e., T>C mutation on the second position and A>T mutation on the third position of the codon, leading to Leu (TTA)-to-Ser (TCA) and -Phe (TTT) amino acid substitutions, respectively. Polymerase chain reaction (PCR) assays were developed for identification of each of these two point mutations. Genotyping of An. stephensi mosquitoes from Alwar by PCR assays revealed the presence of both mutations, with a high frequency of L1014S. The PCR assays developed for detection of the kdr mutations were specific as confirmed by DNA sequencing of PCR-genotyped samples. Two alternative kdr-like mutations, L1014S and L1014F, were detected in An. stephensi with a high allelic frequency of L1014S. The occurrence of L1014S is being reported for the first time in An. stephensi. Two specific PCR assays were developed for detection of two kdr-like mutations in An. stephensi.

  14. MiR-30b Attenuates Neuropathic Pain by Regulating Voltage-Gated Sodium Channel Nav1.3 in Rats

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    Songxue Su

    2017-05-01

    Full Text Available Nav1.3 is a tetrodotoxin-sensitive isoform among voltage-gated sodium channels that are closely associated with neuropathic pain. It can be up-regulated following nerve injury, but its biological function remains uncertain. MicroRNAs (miRNAs are endogenous non-coding RNAs that can regulate post-transcriptional gene expression by binding with their target mRNAs. Using Target Scan software, we discovered that SCN3A is the major target of miR-30b, and we then determined whether miR-30b regulated the expression of Nav1.3 by transfecting miR-30b agomir through the stimulation of TNF-α or by transfecting miR-30b antagomir in primary dorsal root ganglion (DRG neurons. The spinal nerve ligation (SNL model was used to determine the contribution of miR-30b to neuropathic pain, to evaluate changes in Nav1.3 mRNA and protein expression, and to understand the sensitivity of rats to mechanical and thermal stimuli. Our results showed that miR-30b agomir transfection down-regulated Nav1.3 mRNA stimulated with TNF-α in primary DRG neurons. Moreover, miR-30b overexpression significantly attenuated neuropathic pain induced by SNL, with decreases in the expression of Nav1.3 mRNA and protein both in DRG neurons and spinal cord. Activation of Nav1.3 caused by miR-30b antagomir was identified. These data suggest that miR-30b is involved in the development of neuropathic pain, probably by regulating the expression of Nav1.3, and might be a novel therapeutic target for neuropathic pain.Perspective: This study is the first to explore the important role of miR-30b and Nav1.3 in spinal nerve ligation-induced neuropathic pain, and our evidence may provide new insight for improving therapeutic approaches to pain.

  15. Voltage-gated sodium channel expression in mouse DRG after SNI leads to re-evaluation of projections of injured fibers.

    Science.gov (United States)

    Laedermann, Cédric J; Pertin, Marie; Suter, Marc R; Decosterd, Isabelle

    2014-03-11

    Dysregulation of voltage-gated sodium channels (Na(v)s) is believed to play a major role in nerve fiber hyperexcitability associated with neuropathic pain. A complete transcriptional characterization of the different isoforms of Na(v)s under normal and pathological conditions had never been performed on mice, despite their widespread use in pain research. Na(v)s mRNA levels in mouse dorsal root ganglia (DRG) were studied in the spared nerve injury (SNI) and spinal nerve ligation (SNL) models of neuropathic pain. In the SNI model, injured and non-injured neurons were intermingled in lumbar DRG, which were pooled to increase the tissue available for experiments. A strong downregulation was observed for every Na(v)s isoform expressed except for Na(v)1.2; even Na(v)1.3, known to be upregulated in rat neuropathic pain models, was lower in the SNI mouse model. This suggests differences between these two species. In the SNL model, where the cell bodies of injured and non-injured fibers are anatomically separated between different DRG, most Na(v)s were observed to be downregulated in the L5 DRG receiving axotomized fibers. Transcription was then investigated independently in the L3, L4 and L5 DRG in the SNI model, and an important downregulation of many Na(v)s isoforms was observed in the L3 DRG, suggesting the presence of numerous injured neurons there after SNI. Consequently, the proportion of axotomized neurons in the L3, L4 and L5 DRG after SNI was characterized by studying the expression of activating transcription factor 3 (ATF3). Using this marker of nerve injury confirmed that most injured fibers find their cell bodies in the L3 and L4 DRG after SNI in C57BL/6 J mice; this contrasts with their L4 and L5 DRG localization in rats. The spared sural nerve, through which pain hypersensitivity is measured in behavioral studies, mostly projects into the L4 and L5 DRG. The complex regulation of Na(v)s, together with the anatomical rostral shift of the DRG harboring injured

  16. The N-terminal domain of Slack determines the formation and trafficking of Slick/Slack heteromeric sodium-activated potassium channels.

    Science.gov (United States)

    Chen, Haijun; Kronengold, Jack; Yan, Yangyang; Gazula, Valeswara-Rao; Brown, Maile R; Ma, Liqun; Ferreira, Gonzalo; Yang, Youshan; Bhattacharjee, Arin; Sigworth, Fred J; Salkoff, Larry; Kaczmarek, Leonard K

    2009-04-29

    Potassium channels activated by intracellular Na(+) ions (K(Na)) play several distinct roles in regulating the firing patterns of neurons, and, at the single channel level, their properties are quite diverse. Two known genes, Slick and Slack, encode K(Na) channels. We have now found that Slick and Slack subunits coassemble to form heteromeric channels that differ from the homomers in their unitary conductance, kinetic behavior, subcellular localization, and response to activation of protein kinase C. Heteromer formation requires the N-terminal domain of Slack-B, one of the alternative splice variants of the Slack channel. This cytoplasmic N-terminal domain of Slack-B also facilitates the localization of heteromeric K(Na) channels to the plasma membrane. Immunocytochemical studies indicate that Slick and Slack-B subunits are coexpressed in many central neurons. Our findings provide a molecular explanation for some of the diversity in reported properties of neuronal K(Na) channels.

  17. Caracterización del canal epitelial de sodio en sinciciotrofoblasto de placenta humana preeclamptica Characterization of the epithelial sodium channel in human pre-eclampsia syncytiotrophoblast

    Directory of Open Access Journals (Sweden)

    Silvana del Mónaco

    2006-02-01

    epithelial Na channel (ENaC in placental tissue from normal and pre-eclamptic women and in BeWo cell, a model of a human SCT. Changes in the expression of these proteins during sodium transport across the placenta may be related to the pathogeny of pre-eclampsia. The role that ENaC and Na+ transport deregulation play on human placental tissues still remains unknown although in aldosterone-responsive epithelial cells (kidney, colon, abnormalities upregulating its activity lead to increased Na+ uptake and hypertension (i.e. Liddle´s syndrome whereas a diminished channel activity can result in the pseudohypoaldosteronisn syndrome with salt loss and hypotension. Our results show that ENaC is expressed in the apical membrane of normal syncytiotrophoblast. The amplified fragment of a-ENaC was cloned and sequenced having a 100% identity with the sequence of a-ENaC obtained from GenBankTM (SCNN1A, accession number Z92981. We found that the transcription of the a-ENaC mRNA was not detectable in preeclamptic placentas and the protein was not observed with immunohistochemistry staining, probably indicating a low protein expression level. In BeWo cells ENac was found and its expression is regulated by aldosterone, vasopressin, progesterone and estradiol. With patch clamp techniques we studied the currents trough ENaC channels in Bewo cells. We observed currents that were blocked by 10 µM amiloride in cells incubated in 100 nM aldosterone for 12 hs. The amplitude of this current was 20-fold the basal current, a reversal potential of 3 mV and a conductance of 127 ± 26 pS/pF with pulses between -60 and -140 mV. These characteristics are similar to those reported in ENaC channels in several tissues. Although their roles in placenta are still poorly understood, the differences in the expression of ENaC in pre-eclamptic placentas may have consequences for ion transport and these data could lead to future studies concerning the mechanism involved in the pathophysiology of pre-eclampsia.

  18. Neuron-specific chromatin remodeling: a missing link in epigenetic mechanisms underlying synaptic plasticity, memory, and intellectual disability disorders.

    Science.gov (United States)

    Vogel-Ciernia, Annie; Wood, Marcelo A

    2014-05-01

    Long-term memory formation requires the coordinated regulation of gene expression. Until recently nucleosome remodeling, one of the major epigenetic mechanisms for controlling gene expression, had been largely unexplored in the field of neuroscience. Nucleosome remodeling is carried out by chromatin remodeling complexes (CRCs) that interact with DNA and histones to physically alter chromatin structure and ultimately regulate gene expression. Human exome sequencing and gene wide association studies have linked mutations in CRC subunits to intellectual disability disorders, autism spectrum disorder and schizophrenia. However, how mutations in CRC subunits were related to human cognitive disorders was unknown. There appears to be both developmental and adult specific roles for the neuron specific CRC nBAF (neuronal Brg1/hBrm Associated Factor). nBAF regulates gene expression required for dendritic arborization during development, and in the adult, contributes to long-term potentiation, a form of synaptic plasticity, and long-term memory. We propose that the nBAF complex is a novel epigenetic mechanism for regulating transcription required for long-lasting forms of synaptic plasticity and memory processes and that impaired nBAF function may result in human cognitive disorders. Copyright © 2013 Elsevier Ltd. All rights reserved.

  19. Label-free electrochemical immunoassay for neuron specific enolase based on 3D macroporous reduced graphene oxide/polyaniline film.

    Science.gov (United States)

    Zhang, Qi; Li, Xiaoyan; Qian, Chunhua; Dou, Li; Cui, Feng; Chen, Xiaojun

    2018-01-01

    The content of neuron specific enolase (NSE) in serum is considered to be an essential indicator of small cell lung cancer (SCLC). Here, a novel label-free electrochemical immunoassay for the detection of NSE based on the three dimensionally macroporous reduced graphene oxide/polyaniline (3DM rGO/PANI) film has been proposed. The 3DM rGO/PANI film was constructed by electrochemical co-deposition of GO and aniline into the interspaces of a sacrificial silica opal template modified Au slice. During the co-deposition, GO was successfully reduced by aniline and PANI could be deposited on the surfaces of rGO sheets. The ratio of rGO and PANI in the composite was also optimized to achieve the maximum electrochemical performance. The 3DM rGO/PANI composite provided larger specific surface area for the antibody immobilization, exhibited enhanced conductivity for electron transfer, and more important was that PANI acted as the electroactive probe for indicating the NSE concentration. Under the optimal conditions, a linear current response of PANI to NSE concentration was obtained over 0.5 pg mL -1 -10.0 ng mL -1 with a detection limit of 0.1 pg mL -1 . Moreover, the immunosensor showed excellent selectivity, good stability, satisfactory reproducibility and regeneration, and was employed to detect NSE in clinical serum specimens. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. Oligodendrocyte- and Neuron-Specific Nogo-A Restrict Dendritic Branching and Spine Density in the Adult Mouse Motor Cortex.

    Science.gov (United States)

    Zemmar, Ajmal; Chen, Chia-Chien; Weinmann, Oliver; Kast, Brigitt; Vajda, Flora; Bozeman, James; Isaad, Noel; Zuo, Yi; Schwab, Martin E

    2018-06-01

    Nogo-A has been well described as a myelin-associated inhibitor of neurite outgrowth and functional neuroregeneration after central nervous system (CNS) injury. Recently, a new role of Nogo-A has been identified as a negative regulator of synaptic plasticity in the uninjured adult CNS. Nogo-A is present in neurons and oligodendrocytes. However, it is yet unclear which of these two pools regulate synaptic plasticity. To address this question we used newly generated mouse lines in which Nogo-A is specifically knocked out in (1) oligodendrocytes (oligoNogo-A KO) or (2) neurons (neuroNogo-A KO). We show that both oligodendrocyte- and neuron-specific Nogo-A KO mice have enhanced dendritic branching and spine densities in layer 2/3 cortical pyramidal neurons. These effects are compartmentalized: neuronal Nogo-A affects proximal dendrites whereas oligodendrocytic Nogo-A affects distal regions. Finally, we used two-photon laser scanning microscopy to measure the spine turnover rate of adult mouse motor cortex layer 5 cells and find that both Nogo-A KO mouse lines show enhanced spine remodeling after 4 days. Our results suggest relevant control functions of glial as well as neuronal Nogo-A for synaptic plasticity and open new possibilities for more selective and targeted plasticity enhancing strategies.

  1. Serial measurement of neuron specific enolase improves prognostication in cardiac arrest patients treated with hypothermia: A prospective study

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    Storm Christian

    2012-01-01

    Full Text Available Abstract Background Neuron specific enolase (NSE has repeatedly been evaluated for neurological prognostication in patients after cardiac arrest. However, it is unclear whether current guidelines for NSE cutoff levels also apply to cardiac arrest patients treated with hypothermia. Thus, we investigated the prognostic significance of absolute NSE levels and NSE kinetics in cardiac arrest patients treated with hypothermia. Methods In a prospective study of 35 patients resuscitated from cardiac arrest, NSE was measured daily for four days following admission. Outcome was assessed at ICU discharge using the CPC score. All patients received hypothermia treatment for 24 hours at 33°C with a surface cooling device according to current guidelines. Results The cutoff for absolute NSE levels in patients with unfavourable outcome (CPC 3-5 72 hours after cardiac arrest was 57 μg/l with an area under the curve (AUC of 0.82 (sensitivity 47%, specificity 100%. The cutoff level for NSE kinetics in patients with unfavourable outcome (CPC 3-5 was an absolute increase of 7.9 μg/l (AUC 0.78, sensitivity 63%, specificity 100% and a relative increase of 33.1% (AUC 0.803, sensitivity 67%, specificity 100% at 48 hours compared to admission. Conclusion In cardiac arrest patients treated with hypothermia, prognostication of unfavourable outcome by NSE kinetics between admission and 48 hours after resuscitation may be superior to prognostication by absolute NSE levels.

  2. Inflammation-induced reversible switch of the neuron-specific enolase promoter from Purkinje neurons to Bergmann glia.

    Science.gov (United States)

    Sawada, Yusuke; Konno, Ayumu; Nagaoka, Jun; Hirai, Hirokazu

    2016-06-13

    Neuron-specific enolase (NSE) is a glycolytic isoenzyme found in mature neurons and cells of neuronal origin. Injecting adeno-associated virus serotype 9 (AAV9) vectors carrying the NSE promoter into the cerebellar cortex is likely to cause the specific transduction of neuronal cells, such as Purkinje cells (PCs) and interneurons, but not Bergmann glia (BG). However, we found BG-predominant transduction without PC transduction along a traumatic needle tract for viral injection. The enhancement of neuroinflammation by the co-application of lipopolysaccharide (LPS) with AAV9 significantly expanded the BG-predominant area concurrently with the potentiated microglial activation. The BG-predominant transduction was gradually replaced by the PC-predominant transduction as the neuroinflammation dissipated. Experiments using glioma cell cultures revealed significant activation of the NSE promoter due to glucose deprivation, suggesting that intracellularly stored glycogen is metabolized through the glycolytic pathway for energy. Activation of the glycolytic enzyme promoter in BG concurrently with inactivation in PC may have pathophysiological significance for the production of lactate in activated BG and the utilization of lactate, which is provided by the BG-PC lactate shuttle, as a primary energy resource in injured PCs.

  3. Multidrug resistance in epilepsy and polymorphisms in the voltage-gated sodium channel genes SCN1A, SCN2A, and SCN3A: correlation among phenotype, genotype, and mRNA expression.

    Science.gov (United States)

    Kwan, Patrick; Poon, Wai Sang; Ng, Ho-Keung; Kang, David E; Wong, Virginia; Ng, Ping Wing; Lui, Colin H T; Sin, Ngai Chuen; Wong, Ka S; Baum, Larry

    2008-11-01

    Many antiepileptic drugs (AEDs) prevent seizures by blocking voltage-gated brain sodium channels. However, treatment is ineffective in 30% of epilepsy patients, which might, at least in part, result from polymorphisms of the sodium channel genes. We investigated the association of AED responsiveness with genetic polymorphisms and correlated any association with mRNA expression of the neuronal sodium channels. We performed genotyping of tagging and candidate single nucleotide polymorphisms (SNPs) of SCN1A, 2A, and 3A in 471 Chinese epilepsy patients (272 drug responsive and 199 drug resistant). A total of 27 SNPs were selected based on the HapMap database. Genotype distributions in drug-responsive and drug-resistant patients were compared. SCN2A mRNA was quantified by real-time PCR in 24 brain and 57 blood samples. Its level was compared between patients with different genotypes of an SCN2A SNP found to be associated with drug responsiveness. SCN2A IVS7-32A>G (rs2304016) A alleles were associated with drug resistance (odds ratio = 2.1, 95% confidence interval: 1.2-3.7, P=0.007). Haplotypes containing the IVS7-32A>G allele A were also associated with drug resistance. IVS7-32A>G is located within the putative splicing branch site for splicing exons 7 and 9. PCR of reverse-transcribed RNA from blood or brain of patients with different IVS7-32A>G genotypes using primers in exons 7 and 9 showed no skipping of exon 8, and real-time PCR showed no difference in SCN2A mRNA levels among genotypes. Results of this study suggest an association between SCN2A IVS7-32A>G and AED responsiveness, without evidence of an effect on splicing or mRNA expression.

  4. Early detection of response in small cell bronchogenic carcinoma by changes in serum concentrations of creatine kinase, neuron specific enolase, calcitonin, ACTH, serotonin and gastrin releasing peptide

    DEFF Research Database (Denmark)

    Bork, E; Hansen, M; Urdal, P

    1988-01-01

    Creatine kinase (CK-BB), neuron specific enolase (NSE), ACTH, calcitonin, serotonin and gastrin releasing peptide (GRP) were measured in serum or plasma before and immediately after initiation of treatment in patients with small cell lung cancer (SCC). Pretherapeutic elevated concentrations of CK...

  5. Inhibitory actions by ibandronate sodium, a nitrogen-containing bisphosphonate, on calcium-activated potassium channels in Madin–Darby canine kidney cells

    Directory of Open Access Journals (Sweden)

    Sheng-Nan Wu

    2015-01-01

    Full Text Available The nitrogen-containing bisphosphonates used for management of the patients with osteoporosis were reported to influence the function of renal tubular cells. However, how nitrogen-containing bisphosphates exert any effects on ion currents remains controversial. The effects of ibandronate (Iban, a nitrogen-containing bisphosphonate, on ionic channels, including two types of Ca2+-activated K+ (KCa channels, namely, large-conductance KCa (BKCa and intermediate-conductance KCa (IKCa channels, were investigated in Madin–Darby canine kidney (MDCK cells. In whole-cell current recordings, Iban suppressed the amplitude of voltage-gated K+ current elicited by long ramp pulse. Addition of Iban caused a reduction of BKCa channels accompanied by a right shift in the activation curve of BKCa channels, despite no change in single-channel conductance. Ca2+ sensitivity of these channels was modified in the presence of this compound; however, the magnitude of Iban-mediated decrease in BKCa-channel activity under membrane stretch with different negative pressure remained unchanged. Iban suppressed the probability of BKCa-channel openings linked primarily to a shortening in the slow component of mean open time in these channels. The dissociation constant needed for Iban-mediated suppression of mean open time in MDCK cells was 12.2 μM. Additionally, cell exposure to Iban suppressed the activity of IKCa channels, and DC-EBIO or 9-phenanthrol effectively reversed its suppression. Under current-clamp configuration, Iban depolarized the cells and DC-EBIO or PF573228 reversed its depolarizing effect. Taken together, the inhibitory action of Iban on KCa-channel activity may contribute to the underlying mechanism of pharmacological or toxicological actions of Iban and its structurally similar bisphosphonates on renal tubular cells occurring in vivo.

  6. Coevolution of the Ile1,016 and Cys1,534 Mutations in the Voltage Gated Sodium Channel Gene of Aedes aegypti in Mexico.

    Directory of Open Access Journals (Sweden)

    Farah Z Vera-Maloof

    2015-12-01

    Full Text Available Worldwide the mosquito Aedes aegypti (L. is the principal urban vector of dengue viruses. Currently 2.5 billion people are at risk for infection and reduction of Ae. aegypti populations is the most effective means to reduce the risk of transmission. Pyrethroids are used extensively for adult mosquito control, especially during dengue outbreaks. Pyrethroids promote activation and prolong the activation of the voltage gated sodium channel protein (VGSC by interacting with two distinct pyrethroid receptor sites [1], formed by the interfaces of the transmembrane helix subunit 6 (S6 of domains II and III. Mutations of S6 in domains II and III synergize so that double mutants have higher pyrethroid resistance than mutants in either domain alone. Computer models predict an allosteric interaction between mutations in the two domains. In Ae. aegypti, a Ile1,016 mutation in the S6 of domain II was discovered in 2006 and found to be associated with pyrethroid resistance in field populations in Mexico. In 2010 a second mutation, Cys1,534 in the S6 of domain III was discovered and also found to be associated with pyrethroid resistance and correlated with the frequency of Ile1,016.A linkage disequilibrium analysis was performed on Ile1,016 and Cys1,534 in Ae. aegypti collected in Mexico from 2000-2012 to test for statistical associations between S6 in domains II and III in natural populations. We estimated the frequency of the four dilocus haplotypes in 1,016 and 1,534: Val1,016/Phe1,534 (susceptible, Val1,016/Cys1,534, Ile1,016/Phe1,534, and Ile1,016/Cys1,534 (resistant. The susceptible Val1,016/Phe1,534 haplotype went from near fixation to extinction and the resistant Ile1,016/Cys1,534 haplotype increased in all collections from a frequency close to zero to frequencies ranging from 0.5-0.9. The Val1,016/Cys1,534 haplotype increased in all collections until 2008 after which it began to decline as Ile1,016/Cys1,534 increased. However, the Ile1,016/Phe1

  7. Neuron-specific caveolin-1 overexpression improves motor function and preserves memory in mice subjected to brain trauma.

    Science.gov (United States)

    Egawa, Junji; Schilling, Jan M; Cui, Weihua; Posadas, Edmund; Sawada, Atsushi; Alas, Basheer; Zemljic-Harpf, Alice E; Fannon-Pavlich, McKenzie J; Mandyam, Chitra D; Roth, David M; Patel, Hemal H; Patel, Piyush M; Head, Brian P

    2017-08-01

    Studies in vitro and in vivo demonstrate that membrane/lipid rafts and caveolin (Cav) organize progrowth receptors, and, when overexpressed specifically in neurons, Cav-1 augments neuronal signaling and growth and improves cognitive function in adult and aged mice; however, whether neuronal Cav-1 overexpression can preserve motor and cognitive function in the brain trauma setting is unknown. Here, we generated a neuron-targeted Cav-1-overexpressing transgenic (Tg) mouse [synapsin-driven Cav-1 (SynCav1 Tg)] and subjected it to a controlled cortical impact model of brain trauma and measured biochemical, anatomic, and behavioral changes. SynCav1 Tg mice exhibited increased hippocampal expression of Cav-1 and membrane/lipid raft localization of postsynaptic density protein 95, NMDA receptor, and tropomyosin receptor kinase B. When subjected to a controlled cortical impact, SynCav1 Tg mice demonstrated preserved hippocampus-dependent fear learning and memory, improved motor function recovery, and decreased brain lesion volume compared with wild-type controls. Neuron-targeted overexpression of Cav-1 in the adult brain prevents hippocampus-dependent learning and memory deficits, restores motor function after brain trauma, and decreases brain lesion size induced by trauma. Our findings demonstrate that neuron-targeted Cav-1 can be used as a novel therapeutic strategy to restore brain function and prevent trauma-associated maladaptive plasticity.-Egawa, J., Schilling, J. M., Cui, W., Posadas, E., Sawada, A., Alas, B., Zemljic-Harpf, A. E., Fannon-Pavlich, M. J., Mandyam, C. D., Roth, D. M., Patel, H. H., Patel, P. M., Head, B. P. Neuron-specific caveolin-1 overexpression improves motor function and preserves memory in mice subjected to brain trauma. © FASEB.

  8. The superior colliculus of the camel: a neuronal-specific nuclear protein (NeuN) and neuropeptide study

    Science.gov (United States)

    Mensah-Brown, E P K; Garey, L J

    2006-01-01

    In this study we examined the superior colliculus of the midbrain of the one-humped (dromedary) camel, Camelus dromedarius, using Nissl staining and anti-neuronal-specific nuclear protein (NeuN) immunohistochemistry for total neuronal population as well as for the enkephalins, somatostatin (SOM) and substance P (SP). It was found that, unlike in most mammals, the superior colliculus is much larger than the inferior colliculus. The superior colliculus is concerned with visual reflexes and the co-ordination of head, neck and eye movements, which are certainly of importance to this animal with large eyes, head and neck, and apparently good vision. The basic neuronal architecture and lamination of the superior colliculus are similar to that in other mammals. However, we describe for the first time an unusually large content of neurons in the superior colliculus with strong immunoreactivity for met-enkephalin, an endogenous opioid. We classified the majority of these neurons as small (perimeters of 40–50 µm), and localized diffusely throughout the superficial grey and stratum opticum. In addition, large pyramidal-like neurons with perimeters of 100 µm and above were present in the intermediate grey layer. Large unipolar cells were located immediately dorsal to the deep grey layer. By contrast, small neurons (perimeters of 40–50 µm) immunopositive to SOM and SP were located exclusively in the superficial grey layer. We propose that this system may be associated with a pain-inhibiting pathway that has been described from the periaqueductal grey matter, juxtaposing the deep layers of the superior colliculus, to the lower brainstem and spinal cord. Such pain inhibition could be important in relation to the camel's life in the harsh environment of its native deserts, often living in very high temperatures with no shade and a diet consisting largely of thorny branches. PMID:16441568

  9. Research of the serum level of neuron-specific enolase in children with various types of seizure

    Directory of Open Access Journals (Sweden)

    WANG Chun

    2012-10-01

    Full Text Available Objective To explore the relevance between the level changes of serum neuron-specific enolase (NSE and neuronal damage in various seizure types of children with epilepsy. Methods According to the classification criteria of seizure types formulated by International League Against Epilepsy (ILAE in 1981, 190 children with epilepsy were enrolled including tonic-clonic seizure group (41 cases, tonic seizure group (34 cases, clonic seizure group (22 cases, myoclonic seizure group (12 cases, atonic seizure group (17 cases, absence seizure group (22 cases, simple partial seizure group (21 cases and complex partial seizure group (21 cases, and 64 healthy children were enrolled as control group. The long-range vedio-electroencephalogram (VEEG was operated and the blood samples were collected from these cases within 72 h after their seizures. Results The serum NSE levels of epileptic children were significantly higher than control group (P = 0.000. Among these seizure groups, serum NSE in myoclonic seizure group [(32.42 ± 6.62 ng/ml] was significantly higher than the other types, except for tonic-clonic seizure group (P = 0.062. There was no significant difference among the other types (P > 0.05, for all. According to rank correlation analysis, there was positive corrlation between serum NSE levels and VEEG abnormal intensity (rs = 0.613, P = 0.000. Conclusion The serum NSE were markedly increased in children with epilepsy after seizures, suggesting that a certain degree of neuronal damage may result from seizures; the higher NSE levels were, the more serious neuronal damage caused by epileptiform discharges was. The serum NSE levels in myoclonic seizure group and tonic-clonic seizure group were significantly higher than other seizure types, indicating the two kinds of seizures may result in greater neuronal damage.

  10. Diagnostic utility of neuron specific enolase (NSE) in serum and pleural fluids from patients with lung cancer and tuberculosis

    International Nuclear Information System (INIS)

    Alam, J.M.; Baig, J.A.; Asghar, S.S.; Mahmood, S.R.; Ansari, M.A.; Jamil, S.

    2010-01-01

    Several past and recent investigations have focused on the determination of tumor markers in pleural fluids to assess their Usefulness as less invasive replacement method of diagnosis. In this regard, few studies have dealt with the determination of the tumor marker, neuron specific enolase (NSE), in pleural fluids of patients suffering from both benign and malignant diseases such as non small cell lung carcinoma( NSCLC), small cell lung carcinoma( SCLC) and tuberculosis. Therefore, the present study was undertaken to establish the diagnostic utility of NSE in malignant condition by assessing levels in serum and pleural fluids of patients with lung cancer and by comparing it with a benign pulmonary disease of tuberculosis. Pleural fluids were obtained from 22 patients with carcinomatous pleurisy due to SCLC, 11 patients with carcinomatous pleurisy due to non-small cell lung cancer, and 30 patients with tuberculosis pleurisy for comparison purpose. Determination of NSE levels was performed by ECL technology according to the manufacturer's instructions. NSE levels of pleural fluids from SCLC patients were significantly elevated( P<0.0001) when compared with pleural fluids from NSCLC and tuberculosis patients. Moreover, pleural fluids of all 30 tuberculosis patients and 11 NSCLC patients showed moderate significance ( P< O.05 and P < 0.01, respectively) when compared with each other. In addition, cumulative results of NSE levels from SCLC and NSCLC combined also showed high significance (P<0.001) as compared to pleural fluids of tuberculosis patients and moderate significance (P<0.01) when compared with serum levels of both malignant and benign groups. It is concluded that determination of NSE levels in pleural fluids of lung cancer patients noted to be an effective diagnostic tool to differentiate carcinomatous pleurisy due to SCLC from those occurring due to NSCLC and tuberculosis. Further studies with larger group of patients are under progress to further establish

  11. A survey of pyrethroid-resistant populations of Meligethes aeneus F. in Poland indicates the incidence of numerous substitutions in the pyrethroid target site of voltage-sensitive sodium channels in individual beetles.

    Science.gov (United States)

    Wrzesińska, B; Czerwoniec, A; Wieczorek, P; Węgorek, P; Zamojska, J; Obrępalska-Stęplowska, A

    2014-10-01

    The pollen beetle (Meligethes aeneus F.) is the most devastating pest of oilseed rape (Brassica napus) and is controlled by pyrethroid insecticides. However, resistance to pyrethroids in Europe is becoming widespread and predominant. Pyrethroids target the voltage-sensitive sodium channel (VSSC), and mutations in VSSC may be responsible for pyrethroid insensitivity. Here, we analysed individual beetles that were resistant to esfenvalerate, a pyrethroid, from 14 populations that were collected from oilseed rape fields in Poland. We screened the VSSC domains that were presumed to directly interact with pyrethroids. We identified 18 heterozygous nucleic acid substitutions, amongst which six caused an amino acid change: N912S, G926S, I936V, R957G, F1538L and E1553G. Our analysis of the three-dimensional structure of these domains in VSSC revealed that some of these changes may slightly influence the protein structure and hence the docking efficiency of esfenvalerate. Therefore, these mutations may impact the susceptibility of the sodium channel to the action of this insecticide. © 2014 The Royal Entomological Society.

  12. Ciguatoxins Evoke Potent CGRP Release by Activation of Voltage-Gated Sodium Channel Subtypes NaV1.9, NaV1.7 and NaV1.1

    Directory of Open Access Journals (Sweden)

    Filip Touska

    2017-08-01

    Full Text Available Ciguatoxins (CTXs are marine toxins that cause ciguatera fish poisoning, a debilitating disease dominated by sensory and neurological disturbances that include cold allodynia and various painful symptoms as well as long-lasting pruritus. Although CTXs are known as the most potent mammalian sodium channel activator toxins, the etiology of many of its neurosensory symptoms remains unresolved. We recently described that local application of 1 nM Pacific Ciguatoxin-1 (P-CTX-1 into the skin of human subjects induces a long-lasting, painful axon reflex flare and that CTXs are particularly effective in releasing calcitonin-gene related peptide (CGRP from nerve terminals. In this study, we used mouse and rat skin preparations and enzyme-linked immunosorbent assays (ELISA to study the molecular mechanism by which P-CTX-1 induces CGRP release. We show that P-CTX-1 induces CGRP release more effectively in mouse as compared to rat skin, exhibiting EC50 concentrations in the low nanomolar range. P-CTX-1-induced CGRP release from skin is dependent on extracellular calcium and sodium, but independent from the activation of various thermosensory transient receptor potential (TRP ion channels. In contrast, lidocaine and tetrodotoxin (TTX reduce CGRP release by 53–75%, with the remaining fraction involving L-type and T-type voltage-gated calcium channels (VGCC. Using transgenic mice, we revealed that the TTX-resistant voltage-gated sodium channel (VGSC NaV1.9, but not NaV1.8 or NaV1.7 alone and the combined activation of the TTX-sensitive VGSC subtypes NaV1.7 and NaV1.1 carry the largest part of the P-CTX-1-caused CGRP release of 42% and 34%, respectively. Given the contribution of CGRP to nociceptive and itch sensing pathways, our findings contribute to a better understanding of sensory symptoms of acute and chronic ciguatera that may help in the identification of potential therapeutics.

  13. Ciguatoxins Evoke Potent CGRP Release by Activation of Voltage-Gated Sodium Channel Subtypes NaV1.9, NaV1.7 and NaV1.1

    Science.gov (United States)

    Touska, Filip; Sattler, Simon; Malsch, Philipp; Lewis, Richard J.; Zimmermann, Katharina

    2017-01-01

    Ciguatoxins (CTXs) are marine toxins that cause ciguatera fish poisoning, a debilitating disease dominated by sensory and neurological disturbances that include cold allodynia and various painful symptoms as well as long-lasting pruritus. Although CTXs are known as the most potent mammalian sodium channel activator toxins, the etiology of many of its neurosensory symptoms remains unresolved. We recently described that local application of 1 nM Pacific Ciguatoxin-1 (P-CTX-1) into the skin of human subjects induces a long-lasting, painful axon reflex flare and that CTXs are particularly effective in releasing calcitonin-gene related peptide (CGRP) from nerve terminals. In this study, we used mouse and rat skin preparations and enzyme-linked immunosorbent assays (ELISA) to study the molecular mechanism by which P-CTX-1 induces CGRP release. We show that P-CTX-1 induces CGRP release more effectively in mouse as compared to rat skin, exhibiting EC50 concentrations in the low nanomolar range. P-CTX-1-induced CGRP release from skin is dependent on extracellular calcium and sodium, but independent from the activation of various thermosensory transient receptor potential (TRP) ion channels. In contrast, lidocaine and tetrodotoxin (TTX) reduce CGRP release by 53–75%, with the remaining fraction involving L-type and T-type voltage-gated calcium channels (VGCC). Using transgenic mice, we revealed that the TTX-resistant voltage-gated sodium channel (VGSC) NaV1.9, but not NaV1.8 or NaV1.7 alone and the combined activation of the TTX-sensitive VGSC subtypes NaV1.7 and NaV1.1 carry the largest part of the P-CTX-1-caused CGRP release of 42% and 34%, respectively. Given the contribution of CGRP to nociceptive and itch sensing pathways, our findings contribute to a better understanding of sensory symptoms of acute and chronic ciguatera that may help in the identification of potential therapeutics. PMID:28867800

  14. The prognostic value of serum neuron-specific enolase in traumatic brain injury: systematic review and meta-analysis.

    Directory of Open Access Journals (Sweden)

    Feng Cheng

    Full Text Available BACKGROUND: Several studies have suggested that neuron-specific enolase (NSE in serum may be a biomarker of traumatic brain injury. However, whether serum NSE levels correlate with outcomes remains unclear. The purpose of this review was to evaluate the prognostic value of serum NSE protein after traumatic brain injury. METHODS: PubMed and Embase were searched for relevant studies published up to October 2013. Full-text publications on the relationship of NSE to TBI were included if the studies concerned patients with closed head injury, NSE levels in serum after injury, and Glasgow Outcome Scale (GOS or Extended GOS (GOSE scores or mortality. Study design, inclusion criteria, assay, blood sample collection time, NSE cutoff, sensitivity and specificity of NSE for mortality prediction (if sufficient information was provided to calculate these values, and main outcomes were recorded. RESULTS: Sixteen studies were eligible for the current meta-analysis. In the six studies comparing NSE concentrations between TBI patients who died and those who survived, NSE concentrations correlated with mortality (M.D. 0.28, 95% confidence interval (CI, 0.21 to 0.34; I2 55%. In the eight studies evaluating GOS or GOSE, patients with unfavorable outcomes had significantly higher NSE concentrations than those with favorable outcomes (M.D. 0.24, 95% CI, 0.17 to 0.31; I2 64%. From the studies providing sufficient data, the pooled sensitivity and specificity for mortality were 0.79 and 0.50, and 0.72 and 0.66 for unfavorable neurological prognosis, respectively. The areas under the SROC curve (AUC of NSE concentrations were 0.73 (95% CI, 0.66-0.80 for unfavorable outcome and 0.76 (95% CI, 0.62-0.90 for mortality. CONCLUSIONS: Mortality and unfavorable outcome were significantly associated with greater NSE concentrations. In addition, NSE has moderate discriminatory ability to predict mortality and neurological outcome in TBI patients. The optimal discrimination cutoff

  15. A neuron-specific deletion of the microRNA-processing enzyme DICER induces severe but transient obesity in mice.

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    Géraldine M Mang

    Full Text Available MicroRNAs (miRNAs are small, non-coding RNA molecules that regulate gene expression post-transcriptionally. MiRNAs are implicated in various biological processes associated with obesity, including adipocyte differentiation and lipid metabolism. We used a neuronal-specific inhibition of miRNA maturation in adult mice to study the consequences of miRNA loss on obesity development. Camk2a-CreERT2 (Cre+ and floxed Dicer (Dicerlox/lox mice were crossed to generate tamoxifen-inducible conditional Dicer knockouts (cKO. Vehicle- and/or tamoxifen-injected Cre+;Dicerlox/lox and Cre+;Dicer+/+ served as controls. Four cohorts were used to a measure body composition, b follow food intake and body weight dynamics, c evaluate basal metabolism and effects of food deprivation, and d assess the brain transcriptome consequences of miRNA loss. cKO mice developed severe obesity and gained 18 g extra weight over the 5 weeks following tamoxifen injection, mainly due to increased fat mass. This phenotype was highly reproducible and observed in all 38 cKO mice recorded and in none of the controls, excluding possible effects of tamoxifen or the non-induced transgene. Development of obesity was concomitant with hyperphagia, increased food efficiency, and decreased activity. Surprisingly, after reaching maximum body weight, obese cKO mice spontaneously started losing weight as rapidly as it was gained. Weight loss was accompanied by lowered O2-consumption and respiratory-exchange ratio. Brain transcriptome analyses in obese mice identified several obesity-related pathways (e.g. leptin, somatostatin, and nemo-like kinase signaling, as well as genes involved in feeding and appetite (e.g. Pmch, Neurotensin and in metabolism (e.g. Bmp4, Bmp7, Ptger1, Cox7a1. A gene cluster with anti-correlated expression in the cerebral cortex of post-obese compared to obese mice was enriched for synaptic plasticity pathways. While other studies have identified a role for miRNAs in obesity, we

  16. Serum Neuron-Specific Enolase, Biogenic Amino-Acids and Neurobehavioral Function in Lead-Exposed Workers from Lead-Acid Battery Manufacturing Process

    OpenAIRE

    K Ravibabu; T Barman; HR Rajmohan

    2015-01-01

    Background: The interaction between serum neuron-specific enolase (NSE), biogenic amino-acids and neurobehavioral function with blood lead levels in workers exposed to lead form lead-acid battery manufacturing process was not studied. Objective: To evaluate serum NSE and biogenic amino-acids (dopamine and serotonin) levels, and neurobehavioral performance among workers exposed to lead from lead-acid storage battery plant, and its relation with blood lead levels (BLLs). Methods: In a c...

  17. State-dependent compound inhibition of Nav1.2 sodium channels using the FLIPR Vm dye: on-target and off-target effects of diverse pharmacological agents.

    Science.gov (United States)

    Benjamin, Elfrida R; Pruthi, Farhana; Olanrewaju, Shakira; Ilyin, Victor I; Crumley, Gregg; Kutlina, Elena; Valenzano, Kenneth J; Woodward, Richard M

    2006-02-01

    Voltage-gated sodium channels (NaChs) are relevant targets for pain, epilepsy, and a variety of neurological and cardiac disorders. Traditionally, it has been difficult to develop structure-activity relationships for NaCh inhibitors due to rapid channel kinetics and state-dependent compound interactions. Membrane potential (Vm) dyes in conjunction with a high-throughput fluorescence imaging plate reader (FLIPR) offer a satisfactory 1st-tier solution. Thus, the authors have developed a FLIPR Vm assay of rat Nav1.2 NaCh. Channels were opened by addition of veratridine, and Vm dye responses were measured. The IC50 values from various structural classes of compounds were compared to the resting state binding constant (Kr)and inactivated state binding constant (Ki)obtained using patch-clamp electrophysiology (EP). The FLIPR values correlated with Ki but not Kr. FLIPRIC50 values fell within 0.1-to 1.5-fold of EP Ki values, indicating that the assay generally reports use-dependent inhibition rather than resting state block. The Library of Pharmacologically Active Compounds (LOPAC, Sigma) was screened. Confirmed hits arose from diverse classes such as dopamine receptor antagonists, serotonin transport inhibitors, and kinase inhibitors. These data suggest that NaCh inhibition is inherent in a diverse set of biologically active molecules and may warrant counterscreening NaChs to avoid unwanted secondary pharmacology.

  18. Effects on the sodium channel of some new cardiotonic drugs: the 4-, 5-, and 6-pyridyl-2(1H)-quinolone derivatives

    International Nuclear Information System (INIS)

    Grima, M.; Beguin, M.F.; Millanvoye-Van Brussel, E.M.; Decker, N.; Schwartz, J.

    1988-01-01

    To study the action of some new cardiotonic drugs, the 4-, 5-, and 6-pyridyl-2(1H)-quinolone series, on the fast Na+ channel, we compared the effects of eight compounds of this series and milrinone on 22 Na uptake in rat brain synaptosomes and in rat heart muscle cells in culture. The action of tetrodotoxin, a specific Na+ channel blocker, on the positive inotropic effect of these compounds on guinea pig atria was also examined. The new positive inotropic agents enhance 22 Na uptake in synaptosomes in a dose-dependent manner. The activities, expressed as percentage of the maximum activity of protoveratrine B, a classic Na+ channel agonist, reached 70% for milrinone, 60% for compound 7, 57% for compound 6, and less than 50% for the other drugs. For compound 8, but not for milrinone, it was possible to observe a stimulatory effect of the 22 Na uptake on heart muscle cells in culture. Tetrodotoxin (1 and 100 microM) inhibited the stimulatory effects of the inotropic drugs on both preparations. The positive inotropic activities of protoveratrine B, milrinone, and compounds 5 and 8, in guinea pig atria, were inhibited by tetrodotoxin. The affinity and the activity of the other compounds were unchanged in the presence of tetrodotoxin. Our results showed that the stimulation of Na+ influx through the fast Na+ channel might represent a part of the mechanism of action of the inotropic effect of some new cardiotonic drugs

  19. Effects on the sodium channel of some new cardiotonic drugs: the 4-, 5-, and 6-pyridyl-2(1H)-quinolone derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Grima, M.; Beguin, M.F.; Millanvoye-Van Brussel, E.M.; Decker, N.; Schwartz, J.

    1988-09-01

    To study the action of some new cardiotonic drugs, the 4-, 5-, and 6-pyridyl-2(1H)-quinolone series, on the fast Na+ channel, we compared the effects of eight compounds of this series and milrinone on /sup 22/Na uptake in rat brain synaptosomes and in rat heart muscle cells in culture. The action of tetrodotoxin, a specific Na+ channel blocker, on the positive inotropic effect of these compounds on guinea pig atria was also examined. The new positive inotropic agents enhance /sup 22/Na uptake in synaptosomes in a dose-dependent manner. The activities, expressed as percentage of the maximum activity of protoveratrine B, a classic Na+ channel agonist, reached 70% for milrinone, 60% for compound 7, 57% for compound 6, and less than 50% for the other drugs. For compound 8, but not for milrinone, it was possible to observe a stimulatory effect of the /sup 22/Na uptake on heart muscle cells in culture. Tetrodotoxin (1 and 100 microM) inhibited the stimulatory effects of the inotropic drugs on both preparations. The positive inotropic activities of protoveratrine B, milrinone, and compounds 5 and 8, in guinea pig atria, were inhibited by tetrodotoxin. The affinity and the activity of the other compounds were unchanged in the presence of tetrodotoxin. Our results showed that the stimulation of Na+ influx through the fast Na+ channel might represent a part of the mechanism of action of the inotropic effect of some new cardiotonic drugs.

  20. The specificity of Av3 sea anemone toxin for arthropods is determined at linker DI/SS2-S6 in the pore module of target sodium channels.

    Science.gov (United States)

    Gur Barzilai, Maya; Kahn, Roy; Regev, Noa; Gordon, Dalia; Moran, Yehu; Gurevitz, Michael

    2014-10-15

    Av3 is a peptide neurotoxin from the sea anemone Anemonia viridis that shows specificity for arthropod voltage-gated sodium channels (Navs). Interestingly, Av3 competes with a scorpion α-toxin on binding to insect Navs and similarly inhibits the inactivation process, and thus has been classified as 'receptor site-3 toxin', although the two peptides are structurally unrelated. This raises questions as to commonalities and differences in the way both toxins interact with Navs. Recently, site-3 was partly resolved for scorpion α-toxins highlighting S1-S2 and S3-S4 external linkers at the DIV voltage-sensor module and the juxtaposed external linkers at the DI pore module. To uncover channel determinants involved in Av3 specificity for arthropods, the toxin was examined on channel chimaeras constructed with the external linkers of the mammalian brain Nav1.2a, which is insensitive to Av3, in the background of the Drosophila DmNav1. This approach highlighted the role of linker DI/SS2-S6, adjacent to the channel pore, in determining Av3 specificity. Point mutagenesis at DI/SS2-S6 accompanied by functional assays highlighted Trp404 and His405 as a putative point of Av3 interaction with DmNav1. His405 conservation in arthropod Navs compared with tyrosine in vertebrate Navs may represent an ancient substitution that explains the contemporary selectivity of Av3. Trp404 and His405 localization near the membrane surface and the hydrophobic bioactive surface of Av3 suggest that the toxin possibly binds at a cleft by DI/S6. A partial overlap in receptor site-3 of both toxins nearby DI/S6 may explain their binding competition capabilities.

  1. Urine exosomes from healthy and hypertensive pregnancies display elevated level of - α-subunit and cleaved - α- and γ-subunits of the epithelial sodium channel--ENaC

    DEFF Research Database (Denmark)

    Nielsen, Maria Ravn; Frederiksen-Møller, Britta; Langkilde, Rikke Zachar

    2017-01-01

    Preeclampsia is characterized by hypertension, proteinuria, suppression of plasma renin-angiotensin-aldosterone, and impaired urine sodium excretion. Aberrantly filtered plasmin in urine may activate proteolytically the γ-subunit of the epithelial sodium channel (ENaC) and promote Na+ reabsorption...... aldosterone was higher in pregnancy compared to non-pregnancy, and the urine Na/K ratio was lower in preeclampsia compared to healthy pregnancy. Exosome markers ALIX and AQP-2 were stably associated with exosomes across groups. Exosomal α-ENaC-subunit migrated at 75 kDa and dominantly at 50 k......Da and was significantly elevated in pregnancy. In human kidney cortex tissue and two of four pelvis catheter urine, ~90-100 kDa full-length γ-ENaC was detected while no full-length γ-ENaC but 75, 60, and 37 kDa variants dominated in voided urine exosomes. There was no difference in γ-ENaC protein abundances between...

  2. Sodium-calcium exchanger and R-type Ca2+ channels mediate spontaneous [Ca2+](i) oscillations in magnocellular neurones of the rat supraoptic nucleus

    Czech Academy of Sciences Publication Activity Database

    Kortus, Štěpán; Srinivasan, Ch.; Forostyak, O.; Zápotocký, Martin; Ueta, Y.; Syková, E.; Chvátal, A.; Verkhratsky, A.; Dayanithi, G.

    2016-01-01

    Roč. 59, č. 6 (2016), s. 289-298 ISSN 0143-4160 R&D Projects: GA ČR(CZ) GBP304/12/G069 Institutional support: RVO:67985823 Keywords : magnocellular neurosecretory cells * voltage-gated Ca2+ channels * intracellular Ca2+ stores * Ca2+ imaging * Ca2+ oscillations Subject RIV: FH - Neurology Impact factor: 3.707, year: 2016

  3. Sodium-calcium exchanger and R-type Ca2+ channels mediate spontaneous [Ca2+](i) oscillations in magnocellular neurones of the rat supraoptic nucleus

    Czech Academy of Sciences Publication Activity Database

    Kortus, Štěpán; Srinivasan, Chinnapaiyan; Forostyak, Oksana; Zápotocký, M.; Ueta, Y.; Syková, Eva; Chvátal, Alexandr; Verkhratsky, A.; Dayanithi, Govindan

    2016-01-01

    Roč. 59, č. 6 (2016), s. 289-298 ISSN 0143-4160 R&D Projects: GA ČR(CZ) GA14-34077S; GA ČR(CZ) GBP304/12/G069 Institutional support: RVO:68378041 Keywords : 1,4,5-Trisphosphate * Ca(2+) channel toxins * Ca(2+) clearance * Ca(2+) homeostasis Subject RIV: FH - Neurology Impact factor: 3.707, year: 2016

  4. Evaluating the prognosis and degree of brain injury by combined S-100 protein and neuron specific enolase determination

    Institute of Scientific and Technical Information of China (English)

    Xihua Wang; Xinding Zhang

    2006-01-01

    Background:S-100 and neuron specific enolase(NSE)possess the characteristics of specific distribution in brain and relative stable content.Some studies suggest that combined detection of the both is of very importance for evaluating the degree of brain injury.OBJECTIVE: To observe the changes of S-100 protein and NSE levels at different time points after acute brain injury,and evaluate the values of combined detection detection of the both for different injury degrees,pathological changes and prognosis.DESIGN: Case-control observation SETTING: Department of Neurosurgery,Second Affiliated Hospital,Lanzhou University.PARTICIPANTS:Thirty-four inpatients with brain injury,19 males and 15 females,aged 15 to 73 years.who received treatment between September 2005 and May 2006 in the Department of Neurosurgery. Second Affiliated Hospital,Lanzhou University,were recruited.The patients were admitted to hospital at 24 hours after brain injury.After admission,skull CT confirmed that they suffered from brain injury.Following Glasgow coma score(GCS)on admission,the patients were assigned into 3 groups:severe group(GCS 3 to 8 points,n=15).moderate group(GCS 9 to 12 points,n=8)and mild group(GCS 13 to 15 points,n=11).Following Glasgow outcome scale(GOS)at 3 months after brain injury,the patients were assigned into good outcome group (GOS 4 to 5 points,good recovery and moderate disability included,n=19)and poor outcome group(GOS 1 to 3 points,severe disability,vegetative state and death,n=15).Ten subjects who received health examination concurrently were chosen as normal control group,including 6 males and 4 females,aged(45.4±14.3)years.In our laboratory,the normal level of NSE was≤15.2 ng/L,and that of S100 was≤0.105 μg/L.METHODS:①Blood samples of control group were collected when the subjects received health examination Blood samples of patients with brain injury were collected at 24 hours,3,7 and 14 days after injury.According to the instructions of NSE and S-100 kits

  5. Skeletal Muscle Na+ Channel Disorders

    Directory of Open Access Journals (Sweden)

    Dina eSimkin

    2011-10-01

    Full Text Available Five inherited human disorders affecting skeletal muscle contraction have been traced to mutations in the gene encoding the voltage-gated sodium channel Nav1.4. The main symptoms of these disorders are myotonia or periodic paralysis caused by changes in skeletal muscle fiber excitability. Symptoms of these disorders vary from mild or latent disease to incapacitating or even death in severe cases. As new human sodium channel mutations corresponding to disease states become discovered, the importance of understanding the role of the sodium channel in skeletal muscle function and disease state grows.

  6. CELF family RNA-binding protein UNC-75 regulates two sets of mutually exclusive exons of the unc-32 gene in neuron-specific manners in Caenorhabditis elegans.

    Directory of Open Access Journals (Sweden)

    Hidehito Kuroyanagi

    Full Text Available An enormous number of alternative pre-mRNA splicing patterns in multicellular organisms are coordinately defined by a limited number of regulatory proteins and cis elements. Mutually exclusive alternative splicing should be strictly regulated and is a challenging model for elucidating regulation mechanisms. Here we provide models of the regulation of two sets of mutually exclusive exons, 4a-4c and 7a-7b, of the Caenorhabditis elegans uncoordinated (unc-32 gene, encoding the a subunit of V0 complex of vacuolar-type H(+-ATPases. We visualize selection patterns of exon 4 and exon 7 in vivo by utilizing a trio and a pair of symmetric fluorescence splicing reporter minigenes, respectively, to demonstrate that they are regulated in tissue-specific manners. Genetic analyses reveal that RBFOX family RNA-binding proteins ASD-1 and FOX-1 and a UGCAUG stretch in intron 7b are involved in the neuron-specific selection of exon 7a. Through further forward genetic screening, we identify UNC-75, a neuron-specific CELF family RNA-binding protein of unknown function, as an essential regulator for the exon 7a selection. Electrophoretic mobility shift assays specify a short fragment in intron 7a as the recognition site for UNC-75 and demonstrate that UNC-75 specifically binds via its three RNA recognition motifs to the element including a UUGUUGUGUUGU stretch. The UUGUUGUGUUGU stretch in the reporter minigenes is actually required for the selection of exon 7a in the nervous system. We compare the amounts of partially spliced RNAs in the wild-type and unc-75 mutant backgrounds and raise a model for the mutually exclusive selection of unc-32 exon 7 by the RBFOX family and UNC-75. The neuron-specific selection of unc-32 exon 4b is also regulated by UNC-75 and the unc-75 mutation suppresses the Unc phenotype of the exon-4b-specific allele of unc-32 mutants. Taken together, UNC-75 is the neuron-specific splicing factor and regulates both sets of the mutually exclusive

  7. Expression and mutagenesis of the sea anemone toxin Av2 reveals key amino acid residues important for activity on voltage-gated sodium channels.

    Science.gov (United States)

    Moran, Yehu; Cohen, Lior; Kahn, Roy; Karbat, Izhar; Gordon, Dalia; Gurevitz, Michael

    2006-07-25

    Type I sea anemone toxins are highly potent modulators of voltage-gated Na-channels (Na(v)s) and compete with the structurally dissimilar scorpion alpha-toxins on binding to receptor site-3. Although these features provide two structurally different probes for studying receptor site-3 and channel fast inactivation, the bioactive surface of sea anemone toxins has not been fully resolved. We established an efficient expression system for Av2 (known as ATX II), a highly insecticidal sea anemone toxin from Anemonia viridis (previously named A. sulcata), and mutagenized it throughout. Each toxin mutant was analyzed in toxicity and binding assays as well as by circular dichroism spectroscopy to discern the effects derived from structural perturbation from those related to bioactivity. Six residues were found to constitute the anti-insect bioactive surface of Av2 (Val-2, Leu-5, Asn-16, Leu-18, and Ile-41). Further analysis of nine Av2 mutants on the human heart channel Na(v)1.5 expressed in Xenopus oocytes indicated that the bioactive surfaces toward insects and mammals practically coincide but differ from the bioactive surface of a structurally similar sea anemone toxin, Anthopleurin B, from Anthopleura xanthogrammica. Hence, our results not only demonstrate clear differences in the bioactive surfaces of Av2 and scorpion alpha-toxins but also indicate that despite the general conservation in structure and importance of the Arg-14 loop and its flanking residues Gly-10 and Gly-20 for function, the surface of interaction between different sea anemone toxins and Na(v)s varies.

  8. Substituted N-(biphenyl-4'-yl)methyl (R)-2-acetamido-3-methoxypropionamides: potent anticonvulsants that affect frequency (use) dependence and slow inactivation of sodium channels.

    Science.gov (United States)

    Lee, Hyosung; Park, Ki Duk; Torregrosa, Robert; Yang, Xiao-Fang; Dustrude, Erik T; Wang, Yuying; Wilson, Sarah M; Barbosa, Cindy; Xiao, Yucheng; Cummins, Theodore R; Khanna, Rajesh; Kohn, Harold

    2014-07-24

    We prepared 13 derivatives of N-(biphenyl-4'-yl)methyl (R)-2-acetamido-3-methoxypropionamide that differed in type and placement of a R-substituent in the terminal aryl unit. We demonstrated that the R-substituent impacted the compound's whole animal and cellular pharmacological activities. In rodents, select compounds exhibited excellent anticonvulsant activities and protective indices (PI=TD50/ED50) that compared favorably with clinical antiseizure drugs. Compounds with a polar, aprotic R-substituent potently promoted Na+ channel slow inactivation and displayed frequency (use) inhibition of Na+ currents at low micromolar concentrations. The possible advantage of affecting these two pathways to decrease neurological hyperexcitability is discussed.

  9. The Nitric Oxide Donor SNAP-Induced Amino Acid Neurotransmitter Release in Cortical Neurons. Effects of Blockers of Voltage-Dependent Sodium and Calcium Channels

    Science.gov (United States)

    Merino, José Joaquín; Arce, Carmen; Naddaf, Ahmad; Bellver-Landete, Victor; Oset-Gasque, Maria Jesús; González, María Pilar

    2014-01-01

    Background The discovery that nitric oxide (NO) functions as a signalling molecule in the nervous system has radically changed the concept of neuronal communication. NO induces the release of amino acid neurotransmitters but the underlying mechanisms remain to be elucidated. Findings The aim of this work was to study the effect of NO on amino acid neurotransmitter release (Asp, Glu, Gly and GABA) in cortical neurons as well as the mechanism underlying the release of these neurotransmitters. Cortical neurons were stimulated with SNAP, a NO donor, and the release of different amino acid neurotransmitters was measured by HPLC. The involvement of voltage dependent Na+ and Ca2+ channels as well as cGMP in its mechanism of action was evaluated. Conclusions Our results indicate that NO induces release of aspartate, glutamate, glycine and GABA in cortical neurons and that this release is inhibited by ODQ, an inhibitor of soluble guanylate cyclase. Thus, the NO effect on amino acid neurotransmission could be mediated by cGMP formation in cortical neurons. Our data also demonstrate that the Na+ and Ca2+ voltage- dependent calcium channels are involved in the NO effects on cortical neurons. PMID:24598811

  10. The nitric oxide donor SNAP-induced amino acid neurotransmitter release in cortical neurons. Effects of blockers of voltage-dependent sodium and calcium channels.

    Science.gov (United States)

    Merino, José Joaquín; Arce, Carmen; Naddaf, Ahmad; Bellver-Landete, Victor; Oset-Gasque, Maria Jesús; González, María Pilar

    2014-01-01

    The discovery that nitric oxide (NO) functions as a signalling molecule in the nervous system has radically changed the concept of neuronal communication. NO induces the release of amino acid neurotransmitters but the underlying mechanisms remain to be elucidated. The aim of this work was to study the effect of NO on amino acid neurotransmitter release (Asp, Glu, Gly and GABA) in cortical neurons as well as the mechanism underlying the release of these neurotransmitters. Cortical neurons were stimulated with SNAP, a NO donor, and the release of different amino acid neurotransmitters was measured by HPLC. The involvement of voltage dependent Na+ and Ca2+ channels as well as cGMP in its mechanism of action was evaluated. Our results indicate that NO induces release of aspartate, glutamate, glycine and GABA in cortical neurons and that this release is inhibited by ODQ, an inhibitor of soluble guanylate cyclase. Thus, the NO effect on amino acid neurotransmission could be mediated by cGMP formation in cortical neurons. Our data also demonstrate that the Na+ and Ca2+ voltage- dependent calcium channels are involved in the NO effects on cortical neurons.

  11. The nitric oxide donor SNAP-induced amino acid neurotransmitter release in cortical neurons. Effects of blockers of voltage-dependent sodium and calcium channels.

    Directory of Open Access Journals (Sweden)

    José Joaquín Merino

    Full Text Available The discovery that nitric oxide (NO functions as a signalling molecule in the nervous system has radically changed the concept of neuronal communication. NO induces the release of amino acid neurotransmitters but the underlying mechanisms remain to be elucidated.The aim of this work was to study the effect of NO on amino acid neurotransmitter release (Asp, Glu, Gly and GABA in cortical neurons as well as the mechanism underlying the release of these neurotransmitters. Cortical neurons were stimulated with SNAP, a NO donor, and the release of different amino acid neurotransmitters was measured by HPLC. The involvement of voltage dependent Na+ and Ca2+ channels as well as cGMP in its mechanism of action was evaluated.Our results indicate that NO induces release of aspartate, glutamate, glycine and GABA in cortical neurons and that this release is inhibited by ODQ, an inhibitor of soluble guanylate cyclase. Thus, the NO effect on amino acid neurotransmission could be mediated by cGMP formation in cortical neurons. Our data also demonstrate that the Na+ and Ca2+ voltage- dependent calcium channels are involved in the NO effects on cortical neurons.

  12. Low sodium diet (image)

    Science.gov (United States)

    ... for you. Look for these words on labels: low-sodium, sodium-free, no salt added, sodium-reduced, ... for you. Look for these words on labels: low-sodium, sodium-free, no salt added, sodium-reduced, ...

  13. Neuron-specific knockdown of the Drosophila fat induces reduction of life span, deficient locomotive ability, shortening of motoneuron terminal branches and defects in axonal targeting.

    Science.gov (United States)

    Nakamura, Aya; Tanaka, Ryo; Morishita, Kazushige; Yoshida, Hideki; Higuchi, Yujiro; Takashima, Hiroshi; Yamaguchi, Masamitsu

    2017-07-01

    Mutations in FAT4 gene, one of the human FAT family genes, have been identified in Van Maldergem syndrome (VMS) and Hennekam lymphangiectasia-lymphedema syndrome (HS). The FAT4 gene encodes a large protein with extracellular cadherin repeats, EGF-like domains and Laminin G-like domains. FAT4 plays a role in tumor suppression and planar cell polarity. Drosophila contains a human FAT4 homologue, fat. Drosophila fat has been mainly studied with Drosophila eye and wing systems. Here, we specially knocked down Drosophila fat in nerve system. Neuron-specific knockdown of fat shortened the life span and induced the defect in locomotive abilities of adult flies. In consistent with these phenotypes, defects in synapse structure at neuromuscular junction were observed in neuron-specific fat-knockdown flies. In addition, aberrations in axonal targeting of photoreceptor neuron in third-instar larvae were also observed, suggesting that fat involves in axonal targeting. Taken together, the results indicate that Drosophila fat plays an essential role in formation and/or maintenance of neuron. Both VMS and HS show mental retardation and neuronal defects. We therefore consider that these two rare human diseases could possibly be caused by the defect in FAT4 function in neuronal cells. © 2017 Molecular Biology Society of Japan and John Wiley & Sons Australia, Ltd.

  14. The Snake with the Scorpion’s Sting: Novel Three-Finger Toxin Sodium Channel Activators from the Venom of the Long-Glanded Blue Coral Snake (Calliophis bivirgatus

    Directory of Open Access Journals (Sweden)

    Daryl C. Yang

    2016-10-01

    Full Text Available Millions of years of evolution have fine-tuned the ability of venom peptides to rapidly incapacitate both prey and potential predators. Toxicofera reptiles are characterized by serous-secreting mandibular or maxillary glands with heightened levels of protein expression. These glands are the core anatomical components of the toxicoferan venom system, which exists in myriad points along an evolutionary continuum. Neofunctionalisation of toxins is facilitated by positive selection at functional hotspots on the ancestral protein and venom proteins have undergone dynamic diversification in helodermatid and varanid lizards as well as advanced snakes. A spectacular point on the venom system continuum is the long-glanded blue coral snake (Calliophis bivirgatus, a specialist feeder that preys on fast moving, venomous snakes which have both a high likelihood of prey escape but also represent significant danger to the predator itself. The maxillary venom glands of C. bivirgatus extend one quarter of the snake’s body length and nestle within the rib cavity. Despite the snake’s notoriety its venom has remained largely unstudied. Here we show that the venom uniquely produces spastic paralysis, in contrast to the flaccid paralysis typically produced by neurotoxic snake venoms. The toxin responsible, which we have called calliotoxin (δ-elapitoxin-Cb1a, is a three-finger toxin (3FTx. Calliotoxin shifts the voltage-dependence of NaV1.4 activation to more hyperpolarised potentials, inhibits inactivation, and produces large ramp currents, consistent with its profound effects on contractile force in an isolated skeletal muscle preparation. Voltage-gated sodium channels (NaV are a particularly attractive pharmacological target as they are involved in almost all physiological processes including action potential generation and conduction. Accordingly, venom peptides that interfere with NaV function provide a key defensive and predatory advantage to a range of

  15. Experimentation with PEC channel prototype

    International Nuclear Information System (INIS)

    Caponetti, R.; Iacovelli, M.

    1984-01-01

    Experimentation on prototypes of PEC components is presently being carried out at Casaccia CRE. This report shows the results of the first cycle of experimentation of the central channel, concerning the aspects of sodium removal after experimentation

  16. Hidden Sodium

    Centers for Disease Control (CDC) Podcasts

    2013-03-04

    In this podcast, learn about reducing sodium intake by knowing what to eat and the main sources of sodium in the diet. It's important for a healthy lifestyle.  Created: 3/4/2013 by National Center for Chronic Disease Prevention and Health Promotion (NCCDPHP).   Date Released: 3/4/2013.

  17. Dietary sodium

    DEFF Research Database (Denmark)

    Graudal, Niels

    2015-01-01

    The 2013 Institute of Medicine (IOM) report "Sodium Intake in Populations: Assessment of Evidence" did not support the current recommendations of the IOM and the American Heart Association (AHA) to reduce daily dietary sodium intake to below 2,300 mg. The report concluded that the population...

  18. Analytical evaluation of local fault in sodium cooled small fast reactor (4S). Preliminary evaluation of partial blockage in coolant channel

    International Nuclear Information System (INIS)

    Nishimura, Satoshi; Ueda, Nobuyuki

    2007-01-01

    Local faults are fuel failures that result from heat removal imbalance within a single subassembly especially in FBRs. Although the occurrence frequency of local faults is quite low, the licensing body required local faults evaluations in previous FBR plants to confirm the potential for the occurrence of severe fuel subassembly failure and its propagation. A conceptual design of 4S (Super-Safe, Small and Simple) is a sodium cooled fast reactor, which aims at an application to dispersed energy source and long core lifetime. It has a dense arrangement of fuel pins to achieve a long lifetime. Therefore, from the viewpoint of thermal hydraulics, the 4S reactor is considered to have more potential for coolant boiling and fuel pin failure caused by formation of local blockage, comparing these potential in the conventional FBRs. The objective of the present study is to evaluate the effect of local blockage on the coolant flow pattern and temperature rise in the 4S-type fuel subassembly under the normal operation condition. A series of three-dimensional thermal-hydraulic analysis in a single subassembly with local blockage was conducted by the commercialized CFD code 'PHOENICS'. Analytical results show that the peak coolant temperature behind the blockage rises with increasing the blockage area, however, the coolant boiling does not occur under the present analytical conditions. On the other hand, it is found that the liquid phase formation caused by eutectic reactions will occur between the metallic fuel and the cladding under the local blockage condition. However, the penetration rate of liquid phase at fuel-cladding interface is quit low. Therefore, it is expected that rapid fuel pin failure and its propagation to surrounding pins due to liquid phase formation will not occur. (author)

  19. Identification of an Nav1.1 sodium channel (SCN1A) loss-of-function mutation associated with familial simple febrile seizures

    Science.gov (United States)

    Mantegazza, Massimo; Gambardella, Antonio; Rusconi, Raffaella; Schiavon, Emanuele; Annesi, Ferdinanda; Cassulini, Rita Restano; Labate, Angelo; Carrideo, Sara; Chifari, Rosanna; Canevini, Maria Paola; Canger, Raffaele; Franceschetti, Silvana; Annesi, Grazia; Wanke, Enzo; Quattrone, Aldo

    2005-01-01

    Febrile seizures (FS) affect 5–12% of infants and children up to 6 years of age. There is now epidemiological evidence that FS are associated with subsequent afebrile and unprovoked seizures in ≈7% of patients, which is 10 times more than in the general population. Extensive genetic studies have demonstrated that various loci are responsible for familial FS, and the FEB3 autosomal-dominant locus has been identified on chromosome 2q23–24, where the SCN1A gene is mapped. However, gene mutations causing simple FS have not been found yet. Here we show that the M145T mutation of a well conserved amino acid in the first transmembrane segment of domain I of the human Nav1.1 channel α-subunit cosegregates in all 12 individuals of a large Italian family affected by simple FS. Functional studies in mammalian cells demonstrate that the mutation causes a 60% reduction of current density and a 10-mV positive shift of the activation curve. Thus, M145T is a loss-of-function mutant. These results show that monogenic FS should also be considered a channelopathy. PMID:16326807

  20. Sub-chronic testosterone treatment increases the levels of epithelial sodium channel (ENaC-α, β and γ in the kidney of orchidectomized adult male Sprague–Dawley rats

    Directory of Open Access Journals (Sweden)

    Su Yi Loh

    2016-06-01

    Full Text Available Testosterone has been reported to cause blood pressure to increase. However mechanisms that underlie the effect of this hormone on this physiological parameter are currently not well understood. The aims of this study were to investigate effects of testosterone on expression of α, β and γ-epithelial sodium channel (ENaC proteins and messenger RNAs (mRNAs in kidneys, the channel known to be involved in Na+ reabsorption, which subsequently can affect the blood pressure. Methods. Adult male Sprague–Dawley (SD rats were orchidectomized fourteen days prior to receiving seven days treatment with testosterone propionate (125 µg/kg/day or 250 µg/kg/day with or without flutamide (androgen receptor blocker or finasteride (5α-reductase inhibitor. Following sacrifice, the kidneys were removed and were subjected for α, β and γ-ENaC protein and mRNA expression analyses by Western blotting and Real-time PCR (qPCR respectively. The distribution of α, β and γ-ENaC proteins in kidneys were observed by immunofluorescence. Results. The α, β and γ-ENaC proteins and mRNA levels in kidneys were enhanced in rats which received testosterone-only treatment. In these rats, α, β and γ-ENaC proteins were distributed in the distal tubules and collecting ducts of the nephrons. Co-treatment with flutamide or finasteride resulted in the levels of α, β and γ-ENaC proteins and mRNAs in kidneys to decrease. In conclusions, increases in α, β and γ-ENaC protein and mRNA levels in kidneys mainly in the distal tubules and collecting ducts under testosterone influence might lead to enhance Na+ reabsorption which subsequently might cause an increase in blood pressure.

  1. Inhibition of Inactive States of Tetrodotoxin-Sensitive Sodium Channels Reduces Spontaneous Firing of C-Fiber Nociceptors and Produces Analgesia in Formalin and Complete Freund's Adjuvant Models of Pain.

    Directory of Open Access Journals (Sweden)

    David J Matson

    Full Text Available While genetic evidence shows that the Nav1.7 voltage-gated sodium ion channel is a key regulator of pain, it is unclear exactly how Nav1.7 governs neuronal firing and what biophysical, physiological, and distribution properties of a pharmacological Nav1.7 inhibitor are required to produce analgesia. Here we characterize a series of aminotriazine inhibitors of Nav1.7 in vitro and in rodent models of pain and test the effects of the previously reported "compound 52" aminotriazine inhibitor on the spiking properties of nociceptors in vivo. Multiple aminotriazines, including some with low terminal brain to plasma concentration ratios, showed analgesic efficacy in the formalin model of pain. Effective concentrations were consistent with the in vitro potency as measured on partially-inactivated Nav1.7 but were far below concentrations required to inhibit non-inactivated Nav1.7. Compound 52 also reversed thermal hyperalgesia in the complete Freund's adjuvant (CFA model of pain. To study neuronal mechanisms, electrophysiological recordings were made in vivo from single nociceptive fibers from the rat tibial nerve one day after CFA injection. Compound 52 reduced the spontaneous firing of C-fiber nociceptors from approximately 0.7 Hz to 0.2 Hz and decreased the number of action potentials evoked by suprathreshold tactile and heat stimuli. It did not, however, appreciably alter the C-fiber thresholds for response to tactile or thermal stimuli. Surprisingly, compound 52 did not affect spontaneous activity or evoked responses of Aδ-fiber nociceptors. Results suggest that inhibition of inactivated states of TTX-S channels, mostly likely Nav1.7, in the peripheral nervous system produces analgesia by regulating the spontaneous discharge of C-fiber nociceptors.

  2. Lung disease phenotypes caused by overexpression of combinations of α-, β-, and γ-subunits of the epithelial sodium channel in mouse airways.

    Science.gov (United States)

    Livraghi-Butrico, Alessandra; Wilkinson, Kristen J; Volmer, Allison S; Gilmore, Rodney C; Rogers, Troy D; Caldwell, Ray A; Burns, Kimberlie A; Esther, Charles R; Mall, Marcus A; Boucher, Richard C; O'Neal, Wanda K; Grubb, Barbara R

    2018-02-01

    The epithelial Na + channel (ENaC) regulates airway surface hydration. In mouse airways, ENaC is composed of three subunits, α, β, and γ, which are differentially expressed (α > β > γ). Airway-targeted overexpression of the β subunit results in Na + hyperabsorption, causing airway surface dehydration, hyperconcentrated mucus with delayed clearance, lung inflammation, and perinatal mortality. Notably, mice overexpressing the α- or γ-subunit do not exhibit airway Na + hyperabsorption or lung pathology. To test whether overexpression of multiple ENaC subunits produced Na + transport and disease severity exceeding that of βENaC-Tg mice, we generated double (αβ, αγ, βγ) and triple (αβγ) transgenic mice and characterized their lung phenotypes. Double αγENaC-Tg mice were indistinguishable from WT littermates. In contrast, double βγENaC-Tg mice exhibited airway Na + absorption greater than that of βENaC-Tg mice, which was paralleled by worse survival, decreased mucociliary clearance, and more severe lung pathology. Double αβENaC-Tg mice exhibited Na + transport rates comparable to those of βENaC-Tg littermates. However, αβENaC-Tg mice had poorer survival and developed severe parenchymal consolidation. In situ hybridization (RNAscope) analysis revealed both alveolar and airway αENaC-Tg overexpression. Triple αβγENaC-Tg mice were born in Mendelian proportions but died within the first day of life, and the small sample size prevented analyses of cause(s) of death. Cumulatively, these results indicate that overexpression of βENaC is rate limiting for generation of pathological airway surface dehydration. Notably, airway co-overexpression of β- and γENaC had additive effects on Na + transport and disease severity, suggesting dose dependency of these two variables.

  3. A point mutation (L1015F) of the voltage-sensitive sodium channel gene associated with lambda-cyhalothrin resistance in Apolygus lucorum (Meyer-Dür) population from the transgenic Bt cotton field of China.

    Science.gov (United States)

    Zhen, Congai; Gao, Xiwu

    2016-02-01

    In China, the green mirid bug, Apolygus lucorum (Meyer-Dür), has caused severe economic damage to many kinds of crops, especially the cotton and jujubes. Pyrethroid insecticides have been widely used for controlling this pest in the transgenic Bt cotton field. Five populations of A. lucorum collected from cotton crops at different locations in China were evaluated for lambda-cyhalothrin resistance. The results showed that only the population collected from Shandong Province exhibited 30-fold of resistance to lambda-cyhalothrin. Neither PBO nor DEF had obvious synergism when compared the synergistic ratio between SS and RR strain which was originated from the Shandong population. Besides, there were no statistically significant differences (p>0.05) in the carboxylesterase, glutathione S-transferase, or 7-ethoxycoumarin O-deethylase activities between the Shandong population and the laboratory susceptible strain (SS). The full-length sodium channel gene named AlVSSC encoding 2028 amino acids was obtained by RT-PCR and rapid amplification of cDNA ends (RACE). One single point mutation L1015F in the AlVSSC was detected only in the Shandong population. Our results revealed that the L1015F mutation associated with pyrethroid resistance was identified in A. lucorum populations in China. These results will be useful for the rational chemical control of A. lucorum in the transgenic Bt cotton field. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. L1014F-kdr Mutation in Indian Anopheles subpictus (Diptera: Culicidae) Arising From Two Alternative Transversions in the Voltage-Gated Sodium Channel and a Single PIRA-PCR for Their Detection.

    Science.gov (United States)

    Singh, O P; Dykes, C L; Sharma, G; Das, M K

    2015-01-01

    Leucine-to-phenylalanine substitution at residue L1014 in the voltage-gated sodium channel, target site of action for dichlorodiphenyltrichloroethane (DDT) and pyrethroids, is the most common knockdown resistance (kdr) mutation reported in several insects conferring resistance against DDT and pyrethroids. Here, we report presence of two coexisting alternative transversions, A>T and A>C, on the third codon position of L1014 residue in malaria vector Anopheles subpictus Grassi (species A) from Jamshedpur (India), both leading to the same amino acid substitution of Leu-to-Phe with allelic frequencies of 19 and 67%, respectively. A single primer-introduced restriction analysis-polymerase chain reaction (PIRA-PCR) was devised for the identification of L1014F-kdr mutation in An. subpictus resulting from either type of point mutation. Genotyping of samples with PIRA-PCR revealed high frequency (82%) of L1014F-kdr mutation in the study area. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  5. Mapping the interaction site for the tarantula toxin hainantoxin-IV (β-TRTX-Hn2a) in the voltage sensor module of domain II of voltage-gated sodium channels.

    Science.gov (United States)

    Cai, Tianfu; Luo, Ji; Meng, Er; Ding, Jiuping; Liang, Songping; Wang, Sheng; Liu, Zhonghua

    2015-06-01

    Peptide toxins often have pharmacological applications and are powerful tools for investigating the structure-function relationships of voltage-gated sodium channels (VGSCs). Although a group of potential VGSC inhibitors have been reported from tarantula venoms, little is known about the mechanism of their interaction with VGSCs. In this study, we showed that hainantoxin-IV (β-TRTX-Hn2a, HNTX-IV in brief), a 35-residue peptide from Ornithoctonus hainana venom, preferentially inhibited rNav1.2, rNav1.3 and hNav1.7 compared with rNav1.4 and hNav1.5. hNav1.7 was the most sensitive to HNTX-IV (IC50∼21nM). In contrast to many other tarantula toxins that affect VGSCs, HNTX-IV at subsaturating concentrations did not alter activation and inactivation kinetics in the physiological range of voltages, while very large depolarization above +70mV could partially activate toxin-bound hNav1.7 channel, indicating that HNTX-IV acts as a gating modifier rather than a pore blocker. Site-directed mutagenesis indicated that the toxin bound to site 4, which was located on the extracellular S3-S4 linker of hNav1.7 domain II. Mutants E753Q, D816N and E818Q of hNav1.7 decreased toxin affinity for hNav1.7 by 2.0-, 3.3- and 130-fold, respectively. In silico docking indicated that a three-toed claw substructure formed by residues with close contacts in the interface between HNTX-IV and hNav1.7 domain II stabilized the toxin-channel complex, impeding movement of the domain II voltage sensor and inhibiting hNav1.7 activation. Our data provide structural details for structure-based drug design and a useful template for the design of highly selective inhibitors of a specific subtype of VGSCs. Copyright © 2014 Elsevier Inc. All rights reserved.

  6. Neuron-Specific Enolase Is Correlated to Compromised Cerebral Metabolism in Patients Suffering from Acute Bacterial Meningitis; An Observational Cohort Study

    DEFF Research Database (Denmark)

    Bartek, Jiri; Thelin, Eric Peter; Ghatan, Per Hamid

    2016-01-01

    between day 1 (0-24 h) and day 3 (48-72 h) after admission to the NICU (p = 0.0001). No correlation between MD parameters or biomarkers and outcome was found. CONCLUSION: In this observational cohort study, we were able to show that cerebral metabolism is frequently affected in patients with ABM...... in combination with serum samples of biomarkers indicating brain tissue injury, S100B and Neuron Specific Enolase (NSE), additional information might be provided. The aim of this study was to evaluate biomarkers in serum and MD parameters in patients with ABM. METHODS: From a prior study on patients (n = 52......) with a confirmed ABM and impaired consciousness (GCS ≤ 9, or GCS = 10 combined with lumbar spinal opening pressure > 400 mmH2O), a subgroup of patients (n = 21) monitored with intracerebral MD and biomarkers was included in the present study. All patients were treated in the NICU with intracranial pressure (ICP...

  7. Early detection of response in small cell bronchogenic carcinoma by changes in serum concentrations of creatine kinase, neuron specific enolase, calcitonin, ACTH, serotonin and gastrin releasing peptide

    DEFF Research Database (Denmark)

    Bork, E; Hansen, M; Urdal, P

    1988-01-01

    Creatine kinase (CK-BB), neuron specific enolase (NSE), ACTH, calcitonin, serotonin and gastrin releasing peptide (GRP) were measured in serum or plasma before and immediately after initiation of treatment in patients with small cell lung cancer (SCC). Pretherapeutic elevated concentrations of CK...... stage patients and 71% in limited stage patients. Frequent initial monitoring of the substances showed an increase in the concentrations of pretherapeutic elevated CK-BB and NSE on day 1 or 2 followed by a sharp decrease within 1 week. These changes were correlated to objective clinical response...... determined within 4-8 weeks. The results indicate that serum CK-BB and NSE are potential markers for SCC at the time of diagnosis and that changes in the concentrations during the first course of cytostatic therapy are promising as biochemical tests for early detection of response to chemotherapy....

  8. Sodium Oxybate

    Science.gov (United States)

    ... or give your sodium oxybate to anyone else; selling or sharing it is against the law. Store ... dehydrogenase deficiency (an inherited condition in which certain substances build up in the body and cause retardation ...

  9. Sodium Azide

    Science.gov (United States)

    ... Exposure to a large amount of sodium azide by any route may cause these other health effects as well: Convulsions Low blood pressure Loss of consciousness Lung injury Respiratory failure leading to death Slow heart rate ...

  10. The level of neuron-specific enolase and S-100 protein in the cerebrospinal fluid of patients with acute bacterial meningitis

    Directory of Open Access Journals (Sweden)

    A. V. Sokhan

    2016-08-01

    Full Text Available Aim. To evaluate the diagnostic and prognostic role of neuron-specific enolase (NSE and S-100 protein levels in cerebrospinal fluid (CSF of patients with acute bacterial meningitis in the course of the disease. Materials and Methods. 54 cases of acute bacterial meningitis were analyzed, among them – 26 with pneumococcal and 28 with meningococcal etiology. Patients were divided into groups depending on the severity and etiology of disease. In addition to routine laboratory methods, we analyzed the CSF levels of S-100 protein and NSE at admission and after 10 – 12 days of treatment. 12 patients with acute respiratory infections and meningism were examined as a comparison group. Results. In all patients with acute bacterial meningitis CSF NSE and protein S-100 levels were significantly higher than in the control group (P <0,05. CSF neuro specific proteins level was in direct dependence on severity of the disease, and in patients with severe disease was significantly higher than in patients with moderate severity and in the control group (P <0,01. After 10 – 12 days of treatment, the level of the NSE and S-100 protein decreased, but in severe cases was still higher than in the control group (P <0,05. Conclusions. Increased cerebrospinal fluid NSE and S – 100 protein levels shows the presence and value of neurons and glial cells damage in patients with acute bacterial meningitis. CSF S-100 protein and neuron-specific enolase levels help to determine the severity of neurons destruction and glial cells in patients with acute bacterial meningitis. Level of neurospecific protein is in direct proportion to the severity of the disease and is the highest in patients with severe cases (P<0,05. It confirms the diagnostic and prognostic value of CSF neurospecific protein determination in patients with bacterial meningitis.

  11. Direct effect of methylprednisolone on renal sodium and water transport via the principal cells in the kidney

    DEFF Research Database (Denmark)

    Lauridsen, Thomas G; Vase, Henrik; Bech, Jesper N

    2010-01-01

    Glucocorticoids influence renal concentrating and diluting ability. We tested the hypothesis that methylprednisolone treatment increased renal water and sodium absorption by increased absorption via the aquaporin-2 (AQP2) water channels and the epithelial sodium channels (ENaCs) respectively....

  12. Sodium voiding analysis in Kalimer

    International Nuclear Information System (INIS)

    Chang, Won-Pyo; Jeong, Kwan-Seong; Hahn, Dohee

    2001-01-01

    A sodium boiling model has been developed for calculations of the void reactivity feedback as well as the fuel and cladding temperatures in the KALIMER core after onset of sodium boiling. The sodium boiling in liquid metal reactors using sodium as coolant should be modeled because of phenomenon difference observed from that in light water reactor systems. The developed model is a multiple -bubble slug ejection model. It allows a finite number of bubbles in a channel at any time. Voiding is assumed to result from formation of bubbles that fill the whole cross section of the coolant channel except for liquid film left on the cladding surface. The vapor pressure, currently, is assumed to be uniform within a bubble. The present study is focused on not only demonstration of the sodium voiding behavior predicted by the developed model, but also confirmation on qualitative acceptance for the model. In results, the model catches important phenomena for sodium boiling, while further effort should be made for the complete analysis. (author)

  13. Retracted: Addition of a single methyl group to a small molecule sodium channel inhibitor introduces a new mode of gating modulation, by L Wang, SG Zellmer, DM Printzenhoff and NA Castle. British Journal of Pharmacology, volume 172(20): 4905-4918, published in October 2015; DOI 10.1111/bph.13259.

    Science.gov (United States)

    2018-07-01

    The above article, published by the British Journal of Pharmacology in October 2015 (https://bpspubs.onlinelibrary.wiley.com/doi/full/10.1111/bph.13259), has been retracted by agreement between the authors, the journal Editor in Chief and John Wiley & Sons Limited. The retraction has been agreed owing to the discovery of errors in the chemical structure of the synthetic compounds generated. The corrected structure is now available in the article PF-06526290 can both enhance and inhibit conduction through voltage gated sodium channels by L Wang, SG Zellmer, DM Printzenhoff and NA Castle, 2018, https://bpspubs.onlinelibrary.wiley.com/doi/full/10.1111/bph.14338. Reference Wang L, Zellmer SG, Printzenhoff DM, Castle NA (2015). Addition of a single methyl group to a small molecule sodium channel inhibitor introduces a new mode of gating modulation. Br J Pharmacol 172: 4905-4918. https://doi.org/10.1111/bph.13259. © 2018 The British Pharmacological Society.

  14. Anestésicos locais: interação com membranas biológicas e com o canal de sódio voltagem-dependente Local anesthetics: interaction with biological membranes and with the voltage-gated sodium channel

    Directory of Open Access Journals (Sweden)

    Daniele Ribeiro de Araujo

    2008-01-01

    Full Text Available Many theories about the mechanism of action of local anesthetics (LA are described in the literature. Two types of theories can be distinguished: those that focus on the direct effects of LA on their target protein in the axon membranes, i.e. the voltage-gated sodium channel and the ones that take into account the interaction of anesthetic molecules with the lipid membrane phase for the reversible nerve blockage. Since there is a direct correlation between LA hydrophobicity and potency, it is crucial to take this physico-chemical property into account to understand the mechanism of action of LA, be it on the sodium channel protein, lipid(s, or on the whole membrane phase.

  15. Combustion suppressing device for leaked sodium

    International Nuclear Information System (INIS)

    Ooto, Akihiro.

    1985-01-01

    Purpose: To suppress the atmospheric temperature to secure the building safety and shorten the recovery time after the leakage in a chamber for containing sodium leaked from coolant circuit equipments or pipeways of LMFBR type rector by suppressing the combustion of sodium contained in the chamber. Constitution: To the inner wall of a chamber for containing sodium handling equipments, are vertically disposed a panel having a coolant supply port at the upper portion and a coolant discharge port at the lower portion thereof and defined with a coolant flowing channel and a panel for sucking the coolant discharged from the abovementioned panel and exhausting the same externally. Further, a corrugated combustion suppressing plate having apertures for draining the condensated leaked sodium is disposed near the sodium handling equipments. If ruptures are resulted to the sodium handling equipments or pipeway, leaked sodium is passed through the drain apertures in the suppressing plate and stored at the bottom of the containing chamber. (Horiuchi, T.)

  16. Association between Three Mutations, F1565C, V1023G and S996P, in the Voltage-Sensitive Sodium Channel Gene and Knockdown Resistance in Aedes aegypti from Yogyakarta, Indonesia.

    Science.gov (United States)

    Wuliandari, Juli Rochmijati; Lee, Siu Fai; White, Vanessa Linley; Tantowijoyo, Warsito; Hoffmann, Ary Anthony; Endersby-Harshman, Nancy Margaret

    2015-07-23

    Mutations in the voltage-sensitive sodium channel gene (Vssc) have been identified in Aedes aegypti and some have been associated with pyrethroid insecticide resistance. Whether these mutations cause resistance, alone or in combination with other alleles, remains unclear, but must be understood if mutations are to become markers for resistance monitoring. We describe High Resolution Melt (HRM) genotyping assays for assessing mutations found in Ae. aegypti in Indonesia (F1565C, V1023G, S996P) and use them to test for associations with pyrethroid resistance in mosquitoes from Yogyakarta, a city where insecticide use is widespread. Such knowledge is important because Yogyakarta is a target area for releases of Wolbachia-infected mosquitoes with virus-blocking traits for dengue suppression. We identify three alleles across Yogyakarta putatively linked to resistance in previous research. By comparing resistant and susceptible mosquitoes from bioassays, we show that the 1023G allele is associated with resistance to type I and type II pyrethroids. In contrast, F1565C homozygotes were rare and there was only a weak association between individuals heterozygous for the mutation and resistance to a type I pyrethroid. As the heterozygote is expected to be incompletely recessive, it is likely that this association was due to a different resistance mechanism being present. A resistance advantage conferred to V1023G homozygotes through addition of the S996P allele in the homozygous form was suggested for the Type II pyrethroid, deltamethrin. Screening of V1023G and S996P should assist resistance monitoring in Ae. aegypti from Yogyakarta, and these mutations should be maintained in Wolbachia strains destined for release in this city to ensure that these virus-blocking strains of mosquitoes are not disadvantaged, relative to resident populations.

  17. Upregulation of the sodium channel NaVβ4 subunit and its contributions to mechanical hypersensitivity and neuronal hyperexcitability in a rat model of radicular pain induced by local DRG inflammation

    Science.gov (United States)

    Xie, Wenrui; Tan, Zhi-Yong; Barbosa, Cindy; Strong, Judith A.; Cummins, Theodore R.; Zhang, Jun-Ming

    2016-01-01

    High frequency spontaneous firing in myelinated sensory neurons plays a key role in initiating pain behaviors in several different models, including the radicular pain model in which the rat lumbar dorsal root ganglia (DRG) are locally inflamed. The sodium channel isoform NaV1.6 contributes to pain behaviors and spontaneous activity in this model. Among all the isoforms in adult DRG, NaV1.6 is the main carrier of TTX-sensitive resurgent Na currents that allow high-frequency firing. Resurgent currents flow after a depolarization or action potential, as a blocking particle exits the pore. In most neurons the regulatory β4 subunit is potentially the endogenous blocker. We used in vivo siRNA mediated knockdown of NaVβ4 to examine its role in the DRG inflammation model. NaVβ4 but not control siRNA almost completely blocked mechanical hypersensitivity induced by DRG inflammation. Microelectrode recordings in isolated whole DRGs showed that NaVβ4 siRNA blocked the inflammation-induced increase in spontaneous activity of Aβ neurons, and reduced repetitive firing and other measures of excitability. NaVβ4 was preferentially expressed in larger diameter cells; DRG inflammation increased its expression and this was reversed by NaVβ4 siRNA, based on immunohistochemistry and Western blotting. NaVβ4 siRNA also reduced immunohistochemical NaV1.6 expression. Patch clamp recordings of TTX-sensitive Na currents in acutely cultured medium diameter DRG neurons showed that DRG inflammation increased transient and especially resurgent current; effects blocked by NaVβ4 siRNA. NaVβ4 may represent a more specific target for pain conditions that depend on myelinated neurons expressing NaV1.6. PMID:26785322

  18. Neuronal Sodium Channels in Neurodegeneration and Neuroprotection

    Science.gov (United States)

    2002-06-01

    12 A ppendices ...seizures (i.e., phenytoin and epileptic seizures have indicated an acute rise in glucose carbamezapine) but to date the prophylactic use of anticon...rats given acute subcutaneous injections using high-resolution 10-electrode topographic mapping in of RS100642 up to 600 mg/kg also provided no evidence

  19. Immunohistochemical localization of gastrin-releasing peptide, neuronal nitric oxide synthase and neurone-specific enolase in the uterus of the North American opossum, Didelphis virginiana.

    Science.gov (United States)

    Kumano, A; Sasaki, M; Budipitojo, T; Kitamura, N; Krause, W J; Yamada, J

    2005-08-01

    The present study has demonstrated the immunohistochemical localization of gastrin-releasing peptide (GRP), neuronal nitric oxide synthase (nNOS) and neurone-specific enolase (NSE) in the uterus of the North American opossum. Although the presence of GRP, nNOS and NSE has been reported recently in the uterus of eutherian species this is the first description of these peptides in a metatherian species. Metatherian mammals are of interest because in these species it is the prolonged lactation phase of development that is the period of primary reproductive investment rather than intrauterine development as is true of eutherian mammals. The opossum, like other marsupial species, has a very abbreviated gestation period which in Didelphis lasts only 12.5 days. GRP was localized in the cytoplasm of cells forming the surface lining epithelium and the glandular epithelium of the opossum endometrium late in pregnancy, at 11.5 days of gestation. Likewise, immunoreactivities of nNOS and NSE were found primarily within the epithelial cells of the endometrium at 11.5 days of gestation. As these peptides and enzymes appear primarily at the time of establishment of the yolk sac placenta (between day 10 and day 12.5 gestation), the present results strongly suggest that these factors may play a fundamental role in the placentation of the opossum.

  20. The biomarkers neuron-specific enolase and S100b measured the day following admission for severe accidental hypothermia have high predictive values for poor outcome

    DEFF Research Database (Denmark)

    Wiberg, Sebastian; Kjaergaard, Jesper; Kjærgaard, Benedict

    2017-01-01

    was analyzed for NSE and S100b. Follow-up was conducted after 30days and poor neurologic outcome was defined as a Cerebral Performance Category (CPC) score of 3-5. The predictive value of NSE and S100b was assessed as the area under the receiver-operating characteristics curve (AUC). RESULTS: A total of 34......AIM: The aim of the present study was to assess the ability of the biomarkers neuron-specific enolase (NSE) and S100 calcium-binding protein b (S100b) to predict mortality and poor neurologic outcome after 30days in patients admitted with severe accidental hypothermia. METHODS: Consecutive patients...... in 30 unconscious and/or sedated patients. NSE and S100b achieved AUCs of 0.93 and 0.88, respectively, for prediction of 30day mortality and AUCs of 0.88 and 0.87, respectively, for prediction of poor neurologic outcome. CONCLUSIONS: In patients remaining unconscious the day following admission...

  1. Serum neuron-specific enolase, biogenic amino-acids and neurobehavioral function in lead-exposed workers from lead-acid battery manufacturing process.

    Science.gov (United States)

    Ravibabu, K; Barman, T; Rajmohan, H R

    2015-01-01

    The interaction between serum neuron-specific enolase (NSE), biogenic amino-acids and neurobehavioral function with blood lead levels in workers exposed to lead form lead-acid battery manufacturing process was not studied. To evaluate serum NSE and biogenic amino-acids (dopamine and serotonin) levels, and neurobehavioral performance among workers exposed to lead from lead-acid storage battery plant, and its relation with blood lead levels (BLLs). In a cross-sectional study, we performed biochemical and neurobehavioral function tests on 146 workers exposed to lead from lead-acid battery manufacturing process. BLLs were assessed by an atomic absorption spectrophotometer. Serum NSE, dopamine and serotonin were measured by ELISA. Neurobehavioral functions were assessed by CDC-recommended tests---simple reaction time (SRT), symbol digit substitution test (SDST), and serial digit learning test (SDLT). There was a significant correlation (r 0.199, pSDLT and SRT had also a significant positive correlation (r 0.238, p<0.01). NSE had a negative correlation (r -0.194, p<0.05) with serotonin level. Multiple linear regression analysis revealed that both SRT and SDST had positive significant associations with BLL. SRT also had a positive significant association with age. Serum NSE cannot be used as a marker for BLL. The only domain of neurobehavioral function tests that is affected by increased BLL in workers of lead-acid battery manufacturing process is that of the "attention and perception" (SDST).

  2. Neuron-specific feeding RNAi in C. elegans and its use in a screen for essential genes required for GABA neuron function.

    Science.gov (United States)

    Firnhaber, Christopher; Hammarlund, Marc

    2013-11-01

    Forward genetic screens are important tools for exploring the genetic requirements for neuronal function. However, conventional forward screens often have difficulty identifying genes whose relevant functions are masked by pleiotropy. In particular, if loss of gene function results in sterility, lethality, or other severe pleiotropy, neuronal-specific functions cannot be readily analyzed. Here we describe a method in C. elegans for generating cell-specific knockdown in neurons using feeding RNAi and its application in a screen for the role of essential genes in GABAergic neurons. We combine manipulations that increase the sensitivity of select neurons to RNAi with manipulations that block RNAi in other cells. We produce animal strains in which feeding RNAi results in restricted gene knockdown in either GABA-, acetylcholine-, dopamine-, or glutamate-releasing neurons. In these strains, we observe neuron cell-type specific behavioral changes when we knock down genes required for these neurons to function, including genes encoding the basal neurotransmission machinery. These reagents enable high-throughput, cell-specific knockdown in the nervous system, facilitating rapid dissection of the site of gene action and screening for neuronal functions of essential genes. Using the GABA-specific RNAi strain, we screened 1,320 RNAi clones targeting essential genes on chromosomes I, II, and III for their effect on GABA neuron function. We identified 48 genes whose GABA cell-specific knockdown resulted in reduced GABA motor output. This screen extends our understanding of the genetic requirements for continued neuronal function in a mature organism.

  3. Determination of serum neuron specific enolase and glutathion S transferases levels in patients with acute cerebral infarction and its clinical significance

    International Nuclear Information System (INIS)

    Guo Jianyi; Lu Tianhe; Bao Yanmei

    2002-01-01

    Objective: To evaluate the variation of serum neuron specific enolase (NSE) and glutathion S transferases (GST) levels in patients with cerebral infarction and its clinical significance. Methods: The serum levels of NSE in cerebral infarction patients were determined with immunoradiometric assay (IRMA), and the serum level of GST were determined by enzyme immuno sandwich assay (ELISA). Results: Serum NSE levels linked in patients were significantly higher (p<0.01) and GST serum levels were significantly lower (p < 0.01) within 3 days after onset of disease than those at two weeks and those in the controls. There was a positive correlation between serum NSE levels and neurological deficit scores (p < 0.001) and a negative correlation with serum GST levels (p < 0.05). There was also a close relationship between the serum NSE levels and the volume of infarction (p < 0.001). Conclusion: There was a close relationship between the Serum levels of NSE, GST and clinical features of Patients in the early stage of cerebral infarction

  4. Test Your Sodium Smarts

    Science.gov (United States)

    ... You may be surprised to learn how much sodium is in many foods. Sodium, including sodium chloride ... foods with little or no salt. Test your sodium smarts by answering these 10 questions about which ...

  5. Estrogen, progesterone, and genistein differentially regulate levels of expression of α-, β-, and γ-epithelial sodium channel (ENaC) and α-sodium potassium pump (Na⁺/K⁺-ATPase) in the uteri of sex steroid-deficient rats.

    Science.gov (United States)

    Chinigarzadeh, Asma; Muniandy, Sekaran; Salleh, Naguib

    2015-10-01

    Estrogen, progesterone, and genistein could induce changes in uterine fluid volume and Na(+) concentration. Progesterone upregulates expression of epithelial sodium channel (ENaC) and Na(+)/K(+)-ATPase which contributed toward these changes. However, effects of estrogen and genistein were unknown. This study therefore investigated changes in expression of these proteins in the uterus under estrogen, progesterone, and genistein influences to further understand mechanisms underlying sex steroids and phytoestrogen effects on uterine fluid Na(+) regulation. In this study, uteri of ovariectomized female rats receiving 7-day treatment with genistein (25, 50, and 100 mg/kg/day), estrogen (0.8 × 10(-4) mg/kg/day), or progesterone (4 mg/kg/day) were harvested, and expression levels of α-, β-, and γ-ENaC proteins and messenger RNAs (mRNAs) and α-Na(+)/K(+)-ATPase protein were determined by Western blotting (proteins) and real-time polymerase chain reaction (mRNA). Meanwhile, distribution of α-, β-, and γ-ENaC and α-Na(+)/K(+)-ATPase proteins in the uterus was identified by immunohistochemistry. Our findings indicated that expression of α-, β-, and γ-ENaC proteins and mRNAs and α-Na(+)/K(+)-ATPase protein were enhanced under progesterone influence. Lower expressions were noted under estrogen and genistein influences compared to progesterone. Under estrogen, progesterone, and genistein influences, α- and β-ENaC were distributed at apical membrane and γ-ENaC was distributed at apical and basolateral membranes of uterine luminal epithelia. Under progesterone influence, α-Na(+)/K(+)-ATPase was highly expressed at basolateral membrane. In conclusion, high expression of α-, β-, and γ-ENaC and α-Na(+)/K(+)-ATPase under progesterone influence would contribute toward increased uterine fluid Na(+) reabsorption, whereas lesser expression of these proteins under estrogen and genistein influences would contribute toward lower reabsorption of uterine fluid Na

  6. Detection of the V1016G mutation in the voltage-gated sodium channel gene of Aedes aegypti (Diptera: Culicidae) by allele-specific PCR assay, and its distribution and effect on deltamethrin resistance in Thailand.

    Science.gov (United States)

    Stenhouse, Steven A; Plernsub, Suriya; Yanola, Jintana; Lumjuan, Nongkran; Dantrakool, Anchalee; Choochote, Wej; Somboon, Pradya

    2013-08-30

    Resistance to pyrethroid insecticides is widespread among populations of Aedes aegypti, the main vector for the dengue virus. Several different point mutations within the voltage-gated sodium channel (VGSC) gene contribute to such resistance. A mutation at position 1016 in domain II, segment 6 of the VGSC gene in Ae. aegypti leads to a valine to glycine substitution (V1016G) that confers resistance to deltamethrin. This study developed and utilized an allele-specific PCR (AS-PCR) assay that could be used to detect the V1016G mutation. The assay was validated against a number of sequenced DNA samples of known genotype and was determined to be in complete agreement. Larvae and pupae were collected from various localities throughout Thailand. Samples were reared to adulthood and their resistance status against deltamethrin was determined by standard WHO susceptibility bioassays. Deltamethrin-resistant and susceptible insects were then genotyped for the V1016G mutation. Additionally, some samples were genotyped for a second mutation at position 1534 in domain III (F1534C) which is also known to confer pyrethroid resistance. The bioassay results revealed an overall mortality of 77.6%. Homozygous 1016G individuals survived at higher rates than either heterozygous or wild-type (1016 V) mosquitoes. The 1016G mutation was significantly and positively associated with deltamethrin resistance and was widely distributed throughout Thailand. Interestingly, wild-type 1016 V mosquitoes tested were homozygous for the 1534C mutation, and all heterozygous mosquitoes were also heterozygous for 1534C. Mutant homozygous (G/G) mosquitoes expressed the wild-type (F/F) at position 1534. However, the presence of the 1534C mutation was not associated with deltamethrin resistance. Our bioassay results indicate that all populations sampled display some degree of resistance to deltamethrin. Homozygous 1016G mosquitoes were far likelier to survive such exposure. However, resistance in some

  7. Effectiveness of Chlorinated Water, Sodium Hypochlorite, Sodium ...

    African Journals Online (AJOL)

    This study evaluated the efficacy of chlorinated water, sodium hypochlorite solution, sodium chloride solution and sterile distilled water in eliminating pathogenic bacteria on the surfaces of raw vegetables. Lettuce vegetables were dipped in different concentrations of chlorinated water, sodium hypochlorite solution, sodium ...

  8. Associations between the neuron-specific glucocorticoid receptor (NR3C1) Bcl-1 polymorphisms and suicide in cancer patients within the first year of diagnosis.

    Science.gov (United States)

    Park, Subin; Hong, Jin Pyo; Lee, Jong-Keuk; Park, Young-Mi; Park, Yangsoon; Jeon, Juri; Ahn, Myeong Hee; Yoon, Se Chang

    2016-07-11

    Cancer diagnosis is associated with an increased suicide risk, particularly within the first 1 year after diagnosis of cancer. Abnormal function of the hypothalamic-pituitary-adrenal axis has been implicated in the pathophysiology of depression and suicide. We examined genetic associations of the functional Bcl-1 polymorphism of (rs41423247) neuron-specific glucocorticoid receptor (NR3C1) gene, with death by suicide in cancer patients. Suicides occurring within a year of cancer diagnosis ('early suicide') were considered separately from those suicides during the second or subsequent year ('late suicide') after cancer diagnosis. The subjects consisted of 343 cancer patients admitted to a general hospital in Seoul, South Korea from 1996 to 2009, of which 182 had died by suicide and 161 were alive on December 31, 2009. Genomic DNA was extracted from formalin-fixed paraffin-embedded tissue sample of patients with cancer. We conducted a case-control association analysis of Bcl-1 polymorphism of NR3C1 gene. Subjects carrying the GG genotype of Bcl-1 polymorphism were at increased risk of early suicide when compared to those carrying the CC genotype (OR 3.80, 95 % CI 1.02-14.16, p = .047). Similarly, those individuals carrying the GG genotype (recessive mode) had an increased risk of early suicide relative to the CC or CG genotype (OR 3.71, 95 % CI 1.03-13.43, p = .045). However, there were no differences in the genotype distributions of the NR3C1 Bcl-1 polymorphism between late suicide cases and controls. Our findings suggest that the NR3C1 Bcl-1 polymorphisms may be involved in the susceptibility to suicide within the first year after cancer diagnosis among cancer patients in Korean population.

  9. Metabolic syndrome and its components with neuron-specific enolase: a cross-sectional study in large health check-up population in China.

    Science.gov (United States)

    Wang, Shu-Yi; Zha, Xiao-Juan; Zhu, Xin-Ying; Li, Wen-Bo; Ma, Jun; Wu, Ze-Wei; Wu, Huan; Jiang, Ming-Fei; Wen, Yu-Feng

    2018-04-10

    This study was aimed at investigating the relationship between neuron-specific enolase (NSE) and components of metabolic syndrome (MS). Cross-sectional study. Chinese health check-up population. 40 684 health check-up people were enrolled in this study from year 2014 to 2016. OR and coefficient for MS. The percentage of abnormal NSE and MS was 26.85% and 8.85%, respectively. There were significant differences in sex, body mass index, drinking habit, triglycerides (TGs), high-density lipoprotein cholesterol (HDL-C), blood pressure and MS between low-NSE and high-NSE groups. In logistic regression analysis, elevated NSE was present in MS, higher body mass index, hypertriglyceridaemia, hypertension and low-HDL groups. Stepwise linear analysis showed a negative correlation between NSE and fasting blood glucose (FBG) (<6.0 mmol/L), and a positive correlation between NSE and TGs (<20 mmol/L), systolic blood pressure (75-200 mm Hg), HDL-C (0.75-2.50 mmol/L), diastolic blood pressure (<70 mm Hg) and FBG (6.00-20.00 mmol/L). Furthermore, MS was positively correlated with NSE within the range of 2.00-7.50 ng/mL, but had a negative correlation with NSE within the range of 7.50-23.00 ng/mL. There are associations between NSE with MS and its components. The result suggests that NSE may be a potential predictor of MS. Further research could be conducted in discussing the potential mechanism involved. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  10. Obesity development in neuron-specific lipoprotein lipase deficient mice is not responsive to increased dietary fat content or change in fat composition.

    Science.gov (United States)

    Wang, Hong; Taussig, Matthew D; DiPatrizio, Nicholas V; Bruce, Kimberley; Piomelli, Daniele; Eckel, Robert H

    2016-07-01

    We have previously reported that mice with neuron-specific LPL deficiency (NEXLPL-/-) become obese by 16weeks of age on chow. Moreover, these mice had reduced uptake of triglyceride (TG)-rich lipoprotein-derived fatty acids and lower levels of n-3 long chain polyunsaturated fatty acids (n-3 PUFAs) in the hypothalamus. Here, we asked whether increased dietary fat content or altered dietary composition could modulate obesity development in NEXLPL-/- mice. Male NEXLPL-/- mice and littermate controls (WT) were randomly assigned one of three synthetic diets; a high carbohydrate diet (HC, 10% fat), a high-fat diet (HF, 45% fat), or a HC diet supplemented with n-3 PUFAs (HCn-3, 10% fat, Lovaza, GSK®). After 42weeks of HC feeding, body weight and fat mass were increased in the NEXLPL-/- mice compared to WT. WT mice fed a HF diet displayed typical diet-induced obesity, but weight gain was only marginal in HF-fed NEXLPL-/- mice, with no significant difference in body composition. Dietary n-3 PUFA supplementation did not prevent obesity in NEXLPL-/- mice, but was associated with differential modifications in hypothalamic gene expression and PUFA concentration compared to WT mice. Our findings suggest that neuronal LPL is involved in the regulation of body weight and composition in response to either the change in quantity (HF feeding) or quality (n-3 PUFA-enriched) of dietary fat. The precise role of LPL in lipid sensing in the brain requires further investigation. Copyright © 2016 Elsevier Inc. All rights reserved.

  11. Neuron-specific specificity protein 4 bigenomically regulates the transcription of all mitochondria- and nucleus-encoded cytochrome c oxidase subunit genes in neurons.

    Science.gov (United States)

    Johar, Kaid; Priya, Anusha; Dhar, Shilpa; Liu, Qiuli; Wong-Riley, Margaret T T

    2013-11-01

    Neurons are highly dependent on oxidative metabolism for their energy supply, and cytochrome c oxidase (COX) is a key energy-generating enzyme in the mitochondria. A unique feature of COX is that it is one of only four proteins in mammalian cells that are bigenomically regulated. Of its thirteen subunits, three are encoded in the mitochondrial genome and ten are nuclear-encoded on nine different chromosomes. The mechanism of regulating this multisubunit, bigenomic enzyme poses a distinct challenge. In recent years, we found that nuclear respiratory factors 1 and 2 (NRF-1 and NRF-2) mediate such bigenomic coordination. The latest candidate is the specificity factor (Sp) family of proteins. In N2a cells, we found that Sp1 regulates all 13 COX subunits. However, we discovered recently that in primary neurons, it is Sp4 and not Sp1 that regulates some of the key glutamatergic receptor subunit genes. The question naturally arises as to the role of Sp4 in regulating COX in primary neurons. The present study utilized multiple approaches, including chromatin immunoprecipitation, promoter mutational analysis, knockdown and over-expression of Sp4, as well as functional assays to document that Sp4 indeed functionally regulate all 13 subunits of COX as well as mitochondrial transcription factors A and B. The present study discovered that among the specificity family of transcription factors, it is the less known neuron-specific Sp4 that regulates the expression of all 13 subunits of mitochondrial cytochrome c oxidase (COX) enzyme in primary neurons. Sp4 also regulates the three mitochondrial transcription factors (TFAM, TFB1M, and TFB2M) and a COX assembly protein SURF-1 in primary neurons. © 2013 International Society for Neurochemistry.

  12. Serum Neuron-Specific Enolase, Biogenic Amino-Acids and Neurobehavioral Function in Lead-Exposed Workers from Lead-Acid Battery Manufacturing Process

    Directory of Open Access Journals (Sweden)

    K Ravibabu

    2015-01-01

    Full Text Available Background: The interaction between serum neuron-specific enolase (NSE, biogenic amino-acids and neurobehavioral function with blood lead levels in workers exposed to lead form lead-acid battery manufacturing process was not studied. Objective: To evaluate serum NSE and biogenic amino-acids (dopamine and serotonin levels, and neurobehavioral performance among workers exposed to lead from lead-acid storage battery plant, and its relation with blood lead levels (BLLs. Methods: In a cross-sectional study, we performed biochemical and neurobehavioral function tests on 146 workers exposed to lead from lead-acid battery manufacturing process. BLLs were assessed by an atomic absorption spectrophotometer. Serum NSE, dopamine and serotonin were measured by ELISA. Neurobehavioral functions were assessed by CDC-recommended tests—simple reaction time (SRT, symbol digit substitution test (SDST, and serial digit learning test (SDLT. Results: There was a significant correlation (r 0.199, p<0.05 between SDST and BLL. SDLT and SRT had also a significant positive correlation (r 0.238, p<0.01. NSE had a negative correlation (r –0.194, p<0.05 with serotonin level. Multiple linear regression analysis revealed that both SRT and SDST had positive significant associations with BLL. SRT also had a positive significant association with age. Conclusion: Serum NSE cannot be used as a marker for BLL. The only domain of neurobehavioral function tests that is affected by increased BLL in workers of lead-acid battery manufacturing process is that of the “attention and perception” (SDST.

  13. Effect of Memantine on Serum Levels of Neuron-Specific Enolase and on the Glasgow Coma Scale in Patients With Moderate Traumatic Brain Injury.

    Science.gov (United States)

    Mokhtari, Majid; Nayeb-Aghaei, Hossein; Kouchek, Mehran; Miri, Mir Mohammad; Goharani, Reza; Amoozandeh, Arash; Akhavan Salamat, Sina; Sistanizad, Mohammad

    2018-01-01

    Traumatic brain injury (TBI) is a major cause of disability and death globally. Despite significant progress in neuromonitoring and neuroprotection, pharmacological interventions have failed to generate favorable results. We examined the effect of memantine on serum levels of neuron-specific enolase (NSE), a marker of neuronal damage, and the Glasgow Coma Scale (GCS) in patients with moderate TBI. Patients were randomly assigned to the control group (who received standard TBI management) and the treatment group (who, alongside their standard management, received enteral memantine 30 mg twice daily for 7 days). Patients' clinical data, GCS, findings of head computed tomography, and serum NSE levels were collected during the study. Forty-one patients were randomized into the control and treatment groups, 19 and 22 patients respectively. Baseline characteristics and serum NSE levels were not significantly different between the 2 groups. The mean serum NSE levels for the memantine and the control groups on day 3 were 7.95 ± 2.86 and 12.33 ± 7.09 ng/mL, respectively (P = .05), and on day 7 were 5.03 ± 3.25 and 10.04 ± 5.72 ng/mL, respectively (P = .003). The mean GCS on day 3 was 12.3 ± 2.0 and 10.9 ± 1.9 in the memantine and control groups, respectively (P = .03). Serum NSE levels and GCS changes were negatively correlated (r = -0.368, P = .02). Patients with moderate TBI who received memantine had significantly reduced serum NSE levels by day 7 and marked improvement in their GCS scores on day 3 of the study. © 2017, The American College of Clinical Pharmacology.

  14. Ion channels in glioblastoma.

    Science.gov (United States)

    Molenaar, Remco J

    2011-01-01

    Glioblastoma is the most common primary brain tumor with the most dismal prognosis. It is characterized by extensive invasion, migration, and angiogenesis. Median survival is only 15 months due to this behavior, rendering focal surgical resection ineffective and adequate radiotherapy impossible. At this moment, several ion channels have been implicated in glioblastoma proliferation, migration, and invasion. This paper summarizes studies on potassium, sodium, chloride, and calcium channels of glioblastoma. It provides an up-to-date overview of the literature that could ultimately lead to new therapeutic targets.

  15. Sodium in diet

    Science.gov (United States)

    Diet - sodium (salt); Hyponatremia - sodium in diet; Hypernatremia - sodium in diet; Heart failure - sodium in diet ... Too much sodium in the diet may lead to: High blood pressure in some people A serious buildup of fluid in people with heart failure , cirrhosis of ...

  16. Unusual Voltage-Gated Sodium Currents as Targets for Pain.

    Science.gov (United States)

    Barbosa, C; Cummins, T R

    2016-01-01

    Pain is a serious health problem that impacts the lives of many individuals. Hyperexcitability of peripheral sensory neurons contributes to both acute and chronic pain syndromes. Because voltage-gated sodium currents are crucial to the transmission of electrical signals in peripheral sensory neurons, the channels that underlie these currents are attractive targets for pain therapeutics. Sodium currents and channels in peripheral sensory neurons are complex. Multiple-channel isoforms contribute to the macroscopic currents in nociceptive sensory neurons. These different isoforms exhibit substantial variations in their kinetics and pharmacology. Furthermore, sodium current complexity is enhanced by an array of interacting proteins that can substantially modify the properties of voltage-gated sodium channels. Resurgent sodium currents, atypical currents that can enhance recovery from inactivation and neuronal firing, are increasingly being recognized as playing potentially important roles in sensory neuron hyperexcitability and pain sensations. Here we discuss unusual sodium channels and currents that have been identified in nociceptive sensory neurons, describe what is known about the molecular determinants of the complex sodium currents in these neurons. Finally, we provide an overview of therapeutic strategies to target voltage-gated sodium currents in nociceptive neurons. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. Neuron-Specific Enolase Is Correlated to Compromised Cerebral Metabolism in Patients Suffering from Acute Bacterial Meningitis; An Observational Cohort Study.

    Directory of Open Access Journals (Sweden)

    Jiri Bartek

    Full Text Available Patients suffering from acute bacterial meningitis (ABM with a decreased level of consciousness have been shown to have an improved clinical outcome if treated with an intracranial pressure (ICP guided therapy. By using intracranial microdialysis (MD to monitor cerebral metabolism in combination with serum samples of biomarkers indicating brain tissue injury, S100B and Neuron Specific Enolase (NSE, additional information might be provided. The aim of this study was to evaluate biomarkers in serum and MD parameters in patients with ABM.From a prior study on patients (n = 52 with a confirmed ABM and impaired consciousness (GCS ≤ 9, or GCS = 10 combined with lumbar spinal opening pressure > 400 mmH2O, a subgroup of patients (n = 21 monitored with intracerebral MD and biomarkers was included in the present study. All patients were treated in the NICU with intracranial pressure (ICP guided therapy. Serum biomarkers were obtained at admission and every 12 hours. The MD parameters glucose, lactate, pyruvate and glycerol were analyzed. Outcome was assessed at 12-55 months after discharge from hospital. Mann-Whitney U-Test and Wilcoxon matched-pairs signed rank test were applied.The included patients had a mean GCS of 8 (range, 3-10 on admission and increased ICP (>20 mmHg was observed in 62% (n = 13/21 of the patients. Patients with a lactate:pyruvate ratio (LPR >40 (n = 9/21, 43% had significantly higher peak levels of serum NSE (p = 0.03, with similar, although non-significant observations made in patients with high levels of glycerol (>500 μmol/L, p = 0.11 and those with a metabolic crisis (Glucose 25, p = 0.09. No associations between serum S100B and MD parameters were found. Furthermore, median MD glucose levels decreased significantly between day 1 (0-24 h and day 3 (48-72 h after admission to the NICU (p = 0.0001. No correlation between MD parameters or biomarkers and outcome was found.In this observational cohort study, we were able to show

  18. BAF53b, a Neuron-Specific Nucleosome Remodeling Factor, Is Induced after Learning and Facilitates Long-Term Memory Consolidation.

    Science.gov (United States)

    Yoo, Miran; Choi, Kwang-Yeon; Kim, Jieun; Kim, Mujun; Shim, Jaehoon; Choi, Jun-Hyeok; Cho, Hye-Yeon; Oh, Jung-Pyo; Kim, Hyung-Su; Kaang, Bong-Kiun; Han, Jin-Hee

    2017-03-29

    Although epigenetic mechanisms of gene expression regulation have recently been implicated in memory consolidation and persistence, the role of nucleosome-remodeling is largely unexplored. Recent studies show that the functional loss of BAF53b, a postmitotic neuron-specific subunit of the BAF nucleosome-remodeling complex, results in the deficit of consolidation of hippocampus-dependent memory and cocaine-associated memory in the rodent brain. However, it is unclear whether BAF53b expression is regulated during memory formation and how BAF53b regulates fear memory in the amygdala, a key brain site for fear memory encoding and storage. To address these questions, we used viral vector approaches to either decrease or increase BAF53b function specifically in the lateral amygdala of adult mice in auditory fear conditioning paradigm. Knockdown of Baf53b before training disrupted long-term memory formation with no effect on short-term memory, basal synaptic transmission, and spine structures. We observed in our qPCR analysis that BAF53b was induced in the lateral amygdala neurons at the late consolidation phase after fear conditioning. Moreover, transient BAF53b overexpression led to persistently enhanced memory formation, which was accompanied by increase in thin-type spine density. Together, our results provide the evidence that BAF53b is induced after learning, and show that such increase of BAF53b level facilitates memory consolidation likely by regulating learning-related spine structural plasticity. SIGNIFICANCE STATEMENT Recent works in the rodent brain begin to link nucleosome remodeling-dependent epigenetic mechanism to memory consolidation. Here we show that BAF53b, an epigenetic factor involved in nucleosome remodeling, is induced in the lateral amygdala neurons at the late phase of consolidation after fear conditioning. Using specific gene knockdown or overexpression approaches, we identify the critical role of BAF53b in the lateral amygdala neurons for

  19. Some problems of leaks in sodium-water steam generator

    International Nuclear Information System (INIS)

    Kozlov, F.A.; Sergeev, G.V.; Sednev, A.R.; Makarov, V.M.

    1976-01-01

    The paper contains data on wastage of steam generator structural materials and high-nickel alloys in the zone of water leakage into sodium as well as investigation results for self-enlargement of water leaks into sodium through defects in these materials. It is shown that the rate of material damage in the zone of sodium-water reaction and in the channel with water leaking-out decreases with increasing nickel content in steels and strongly depends on sodium temperature. The paper presents experimentally obtained dependences of leakage self-enlargement rates on sodium temperature and leakage size

  20. Sodium technology handbook

    International Nuclear Information System (INIS)

    2005-09-01

    This document was published as a textbook for the education and training of personnel working for operations and maintenances of sodium facilities including FBR plants and those engaged in R and D activities related to sodium technology. This handbook covers the following technical areas. Properties of sodium. Compatibilities of sodium with materials. Thermalhydraulics and structural integrity. Sodium systems and components. Sodium instrumentations. Sodium handling technology. Sodium related accident evaluation and countermeasures for FBRs. Operation, maintenance and repair technology of sodium facilities. Safety measures related to sodium. Laws, regulations and internal rules related to sodium. The plannings and discussions of the handbook were made in the Sodium Technology Education Committee organized in O-arai Engineering Center consisting of the representatives of the related departments including Tsuruga headquarters. Experts in various departments participated in writing individual technical subjects. (author)

  1. The sodium coolant

    International Nuclear Information System (INIS)

    Rodriguez, G.

    2004-01-01

    The sodium is the best appropriate coolant for the fast neutrons reactors technology. Thus the fast neutrons reactors development is intimately bound to the sodium technology. This document presents the sodium as a coolant point of view: atomic structure and characteristics, sodium impacts on the fast neutron reactors technology, chemical properties of the sodium and the consequences, quality control in a nuclear reactor, sodium treatment. (A.L.B.)

  2. A novel Ile1455Thr variant in the skeletal muscle sodium channel alpha-subunit in a patient with a severe adult-onset proximal myopathy with electrical myotonia and a patient with mild paramyotonia phenotype

    NARCIS (Netherlands)

    Bednarz, M.; Stunnenberg, B.C.; Kusters, B.; Kamsteeg, E.J.; Saris, C.G.J.; Groome, J.; Winston, V.; Meola, G.; Jurkat-Rott, K.; Voermans, N.C.

    2017-01-01

    In sodium channelopathies, a severe fixed myopathy caused by a dominant mutation is rare. We describe two unrelated patients with a novel variant, p.Ile1455Thr, with phenotypes of paramyotonia in one case and fixed proximal myopathy with latent myotonia in another. In-vitro whole cell patch-clamp

  3. Behaviour of carbon-bearing impurity suspensions in sodium loops

    Energy Technology Data Exchange (ETDEWEB)

    Kozlov, F A; Zagorulko, Yu I; Alexseev, V V [Institute of Physics and Power Engineering, Obninsk (USSR)

    1980-05-01

    The experimental estimation results of the carbon-bearing impurity particle sizes in sodium by the sedimentometric analysis methods are presented. The techniques and results of the mass transfer calculations between the sodium flows contained the carbon-bearing impurity disperse phase, and the channel walls, the carbon particles solution kinetics and the soluble carbon near-wall concentration in channel with allowance for the flow-wall mass transfer processes, are given. (author)

  4. Behaviour of carbon-bearing impurity suspensions in sodium loops

    International Nuclear Information System (INIS)

    Kozlov, F.A.; Zagorulko, Yu.I.; Alexseev, V.V.

    1980-01-01

    The experimental estimation results of the carbon-bearing impurity particle sizes in sodium by the sedimentometric analysis methods are presented. The techniques and results of the mass transfer calculations between the sodium flows contained the carbon-bearing impurity disperse phase, and the channel walls, the carbon particles solution kinetics and the soluble carbon near-wall concentration in channel with allowance for the flow-wall mass transfer processes, are given. (author)

  5. PG BN 1600 sodium fire protection system

    International Nuclear Information System (INIS)

    Bar, J.; Urbancik, L.

    1978-12-01

    A design was developed of a fire protection system for steam generator of a 1600 MW sodium cooled fast reactor (BN-1600). Chemical reactions are described of liquid sodium with atmospheric components and solid materials coming into contact with sodium in its release from the steam generator, and in safeguarding protection against sodium fires. The requirements for the purity of nitrogen as an atmosphere inert to liquid sodium are given. Characteristics and basic parameters are shown of level and spray fires, elementary terms are explained concerning the properties of aerosols formed during fires, the methods and means of release signalling and fire alarm are described as are fire precautions using fire-fighting equipment, modifying the support tank and the cell bottom and building sewage pits. The design of the system comprises an alarm system for liquid sodium using point and line electric contact sensors and flame photometer based aerosol sensors as well as a fire-fighting system based on the system of channelling liquid sodium into emergency discharge tanks filled with an inert gas, a set of fire extinguishers and other fire fighting material, and measures for the elimination of sodium fire consequences. (J.B.)

  6. Detection Test for Leakage of CO2 into Sodium Loop

    International Nuclear Information System (INIS)

    Park, Sun Hee; Wi, Myung-Hwan; Min, Jae Hong

    2015-01-01

    This report is about the facility for the detection test for leakage of CO 2 into sodium loop. The facility for the detection test for leakage of CO 2 into sodium loop was introduced. The test will be carried out. Our experimental results are going to be expected to be used for approach methods to detect CO 2 leaking into sodium in heat exchangers. A sodium-and-carbon dioxide (Na-CO 2 ) heat exchanger is one of the key components for the supercritical CO 2 Brayton cycle power conversion system of sodium-cooled fast reactors (SFRs). A printed circuit heat exchanger (PCHE) is considered for the Na-CO 2 heat exchanger, which is known to have potential for reducing the volume occupied by the exchangers compared to traditional shell-and-tube heat exchangers. Among various issues about the Na- CO 2 exchanger, detection of CO 2 leaking into sodium in the heat exchanger is most important thing for its safe operation. It is known that reaction products from sodium and CO 2 such as sodium carbonate (Na 2 CO 3 ) and amorphous carbon are hardly soluble in sodium, which cause plug sodium channels. Detection technique for Na 2 CO 3 in sodium loop has not been developed yet. Therefore, detection of CO 2 and CO from reaction of sodium and CO 2 are proper to detect CO 2 leakage into sodium loop

  7. Liquid sodium pool fires

    Energy Technology Data Exchange (ETDEWEB)

    Casselman, C [DSN/SESTR, Centre de Cadarache, Saint-Paul-lez-Durance (France)

    1979-03-01

    Experimental sodium pool combustion results have led to a definition of the combustion kinetics, and have revealed the hazards of sodium-concrete contact reactions and the possible ignition of organic matter (paint) by hydration of sodium peroxide aerosols. Analysis of these test results shows that the controlling mechanism is sodium evaporation diffusion. (author)

  8. Liquid sodium pool fires

    International Nuclear Information System (INIS)

    Casselman, C.

    1979-01-01

    Experimental sodium pool combustion results have led to a definition of the combustion kinetics, and have revealed the hazards of sodium-concrete contact reactions and the possible ignition of organic matter (paint) by hydration of sodium peroxide aerosols. Analysis of these test results shows that the controlling mechanism is sodium evaporation diffusion. (author)

  9. Small liquid sodium leaks

    International Nuclear Information System (INIS)

    Dufresne, J.; Rochedereux, Y.; Antonakas, D.; Casselman, C.; Malet, J.C.

    1986-05-01

    Usually, pessimistic considerations inassessing the safety of secondary sodium loops in LMFBR reactor lead to assume guillotine rupture releasing a large amount of sodium estimate the consequences of large sodium fires. In order to reduce these consequences, one has to detect the smallest leak as soon as possible and to evaluate the future of an initial small leak. Analysis of the relationship between crack size and sodium outflow rate; Analysis of a sodium pipe with a small open crack

  10. Effects of channel noise on firing coherence of small-world Hodgkin-Huxley neuronal networks

    Science.gov (United States)

    Sun, X. J.; Lei, J. Z.; Perc, M.; Lu, Q. S.; Lv, S. J.

    2011-01-01

    We investigate the effects of channel noise on firing coherence of Watts-Strogatz small-world networks consisting of biophysically realistic HH neurons having a fraction of blocked voltage-gated sodium and potassium ion channels embedded in their neuronal membranes. The intensity of channel noise is determined by the number of non-blocked ion channels, which depends on the fraction of working ion channels and the membrane patch size with the assumption of homogeneous ion channel density. We find that firing coherence of the neuronal network can be either enhanced or reduced depending on the source of channel noise. As shown in this paper, sodium channel noise reduces firing coherence of neuronal networks; in contrast, potassium channel noise enhances it. Furthermore, compared with potassium channel noise, sodium channel noise plays a dominant role in affecting firing coherence of the neuronal network. Moreover, we declare that the observed phenomena are independent of the rewiring probability.

  11. Under sodium ultrasonic imaging system for PFBR

    International Nuclear Information System (INIS)

    Patankar, V.H.; Lalwani, S.K.; Agashe, A.A.

    2014-01-01

    Under Sodium UltraSonic Scanner (USUSS) has been developed to detect the growth and protrusion of fuel sub-assemblies of PFBR, submerged in liquid sodium by using the ultrasonic imaging technique during reactor shut-down when liquid sodium is at 180 ℃. The imaging is carried out prior to every Fuel handling operation. Electronics Division, BARC has designed and developed an 8-Channel Ultrasonic Imaging System (UIS) which consists of 4 downward viewing and 4 side viewing ultrasonic transducers alongwith pulser-receiver, signal processing electronics hardware and software. An automated mechanical scanner developed by IGCAR houses sodium immersible transducers to image the fuel sub assemblies. The system has been successfully tested with dummy protruding and grown FSAs, submerged under liquid sodium. Such ultrasonic imaging systems are not available to India from international market. The USUSS developed indigenously has all the features available in similar systems developed by other countries. After every imaging campaign, the mechanical scanner containing ultrasonic transducers is stored in the Argon filled storage-pit. Before every campaign of USUSS, it is necessary to check the healthiness of the sodium immersible and contaminated ultrasonic transducers, as the under-sodium scanner is decontaminated once in five years. For this purpose, a novel Non Contact Ultrasonic Inspection System (NCUIS) has been designed and developed by Electronics Division, BARC to check the functionality of the high-temperature and contaminated transducers of USUSS, using air-coupled ultrasonic technique. (author)

  12. Ciguatoxins Evoke Potent CGRP Release by Activation of Voltage-Gated Sodium Channel Subtypes Na(V)1.9, Na(V)1.7 and Na(V)1.1

    Czech Academy of Sciences Publication Activity Database

    Touška, Filip; Sattler, S.; Malsch, P.; Lewis, R. J.; Reeh, P. W.; Zimmermann, K.

    2017-01-01

    Roč. 15, č. 9 (2017), č. článku 269. ISSN 1660-3397 Institutional support: RVO:67985823 Keywords : voltage-gated calcium channels * calcitonin-gene related peptide * tetrodotoxin * TTX * P-CTX-1 * TRPA1 * TRPC5 * neuropathic pain * neurogenic inflammation Subject RIV: FH - Neurology OBOR OECD: Neurosciences (including psychophysiology Impact factor: 3.503, year: 2016

  13. Sodium Ferric Gluconate Injection

    Science.gov (United States)

    Sodium ferric gluconate injection is used to treat iron-deficiency anemia (a lower than normal number of ... are also receiving the medication epoetin (Epogen, Procrit). Sodium ferric gluconate injection is in a class of ...

  14. Naproxen sodium overdose

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/002507.htm Naproxen sodium overdose To use the sharing features on this page, please enable JavaScript. Naproxen sodium is a nonsteroidal anti-inflammatory drug (NSAID) used ...

  15. Sodium hydroxide poisoning

    Science.gov (United States)

    Sodium hydroxide is a very strong chemical. It is also known as lye and caustic soda. This ... poisoning from touching, breathing in (inhaling), or swallowing sodium hydroxide. This article is for information only. Do ...

  16. Sodium pumping: pump problems

    International Nuclear Information System (INIS)

    Guer, M.; Guiton, P.

    Information on sodium pumps for LMFBR type reactors is presented concerning ring pump design, pool reactor pump design, secondary pumps, sodium bearings, swivel joints of the oscillating annulus, and thermal shock loads

  17. Docusate Sodium and Pregnancy

    Science.gov (United States)

    ... a risk of miscarriage. Can use of docusate sodium during pregnancy cause birth defects? Few studies have been done to look at the possible risks of docusate sodium during pregnancy. However, the available studies show that when used ...

  18. Sodium carbonate poisoning

    Science.gov (United States)

    Sodium carbonate (known as washing soda or soda ash) is a chemical found in many household and industrial products. This article focuses on poisoning due to sodium carbonate. This article is for information only. Do NOT ...

  19. ELTA: Citatrademark: Sodium measurement

    International Nuclear Information System (INIS)

    Mauvais, O.

    2002-01-01

    ELTA is pleased to present its last model of Sodium analyzers: CITA 2340: Automatically controlled sodium meter, integrating more automation and performances results respecting costs and wastes reduction. (authors)

  20. Liquid sodium technology research

    International Nuclear Information System (INIS)

    Kim, W.C.; Lee, Y.W.; Nam, H.Y.; Chun, S.Y.; Kim, J.; Won, S.Y.

    1982-01-01

    This report describes the technology of impurity control and measurement of liquid sodium, problems associated with material degradation and change of heat transfer characteristics in liquid sodium, and the conceptual design of multipurpose sodium test loop. Discussion and the subsequent analysis are also made with regard to the test results for the sodium-H 2 0 reaction and its effects on the system. (author)

  1. Sodium sieving in children

    NARCIS (Netherlands)

    Rusthoven, Esther; Krediet, Raymond T.; Willems, Hans L.; Monnens, Leo A.; Schröder, Cornelis H.

    2005-01-01

    Sodium sieving is a consequence of dissociation between the amount of water and sodium transported over the peritoneal membrane. This dissociation occurs in the presence of aquaporin-mediated water transport. Sieving of sodium can be used as a rough measure for aquaporin-mediated water transport.

  2. ASIC3 channels in multimodal sensory perception.

    Science.gov (United States)

    Li, Wei-Guang; Xu, Tian-Le

    2011-01-19

    Acid-sensing ion channels (ASICs), which are members of the sodium-selective cation channels belonging to the epithelial sodium channel/degenerin (ENaC/DEG) family, act as membrane-bound receptors for extracellular protons as well as nonproton ligands. At least five ASIC subunits have been identified in mammalian neurons, which form both homotrimeric and heterotrimeric channels. The highly proton sensitive ASIC3 channels are predominantly distributed in peripheral sensory neurons, correlating with their roles in multimodal sensory perception, including nociception, mechanosensation, and chemosensation. Different from other ASIC subunit composing ion channels, ASIC3 channels can mediate a sustained window current in response to mild extracellular acidosis (pH 7.3-6.7), which often occurs accompanied by many sensory stimuli. Furthermore, recent evidence indicates that the sustained component of ASIC3 currents can be enhanced by nonproton ligands including the endogenous metabolite agmatine. In this review, we first summarize the growing body of evidence for the involvement of ASIC3 channels in multimodal sensory perception and then discuss the potential mechanisms underlying ASIC3 activation and mediation of sensory perception, with a special emphasis on its role in nociception. We conclude that ASIC3 activation and modulation by diverse sensory stimuli represent a new avenue for understanding the role of ASIC3 channels in sensory perception. Furthermore, the emerging implications of ASIC3 channels in multiple sensory dysfunctions including nociception allow the development of new pharmacotherapy.

  3. CFD Modeling of Sodium-Oxide Deposition in Sodium-Cooled Fast Reactor Compact Heat Exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Tatli, Emre; Ferroni, Paolo; Mazzoccoli, Jason

    2015-09-02

    The possible use of compact heat exchangers (HXs) in sodium-cooled fast reactors (SFR) employing a Brayton cycle is promising due to their high power density and resulting small volume in comparison with conventional shell-and-tube HXs. However, the small diameter of their channels makes them more susceptible to plugging due to Na2O deposition during accident conditions. Although cold traps are designed to reduce oxygen impurity levels in the sodium coolant, their failure, in conjunction with accidental air ingress into the sodium boundary, could result in coolant oxygen levels that are above the saturation limit in the cooler parts of the HX channels. This can result in Na2O crystallization and the formation of solid deposits on cooled channel surfaces, limiting or even blocking coolant flow. The development of analysis tools capable of modeling the formation of these deposits in the presence of sodium flow will allow designers of SFRs to properly size the HX channels so that, in the scenario mentioned above, the reactor operator has sufficient time to detect and react to the affected HX. Until now, analytical methodologies to predict the formation of these deposits have been developed, but never implemented in a high-fidelity computational tool suited to modern reactor design techniques. This paper summarizes the challenges and the current status in the development of a Computational Fluid Dynamics (CFD) methodology to predict deposit formation, with particular emphasis on sensitivity studies on some parameters affecting deposition.

  4. Proteinuric diseases with sodium retention: Is plasmin the link?

    DEFF Research Database (Denmark)

    Svenningsen, Per; Skøtt, Ole; Jensen, Boye L

    2012-01-01

    1. Sodium retention in disease states characterized by proteinuria, such as nephrotic syndrome, preeclampsia, and diabetic nephropathy, occurs through poorly understood mechanism(s). 2. In the nephrotic syndrome, data from experimental and clinical studies indicate that the sodium retention...... originates in the renal cortical collecting duct and involves hyper-activity of the epithelial sodium channel (ENaC). 3. The stimulus for the increased ENaC activity does not appear to involve any of the classical sodium retaining mechanisms, such as the renin-angiotensin-aldosterone system, arginine...... and diabetic nephropathy, which are also characterized by proteinuria and sodium retention. 7. In this review, we will examine the evidence for a role of urinary serine protease activity in the development of sodium and water retention in diseases characterised by proteinuria with a focus on the nephrotic...

  5. Major Channels Involved In Neuropsychiatric Disorders And Therapeutic Perspectives

    Directory of Open Access Journals (Sweden)

    Paola eImbrici

    2013-05-01

    Full Text Available Voltage-gated ion channels are important mediators of physiological functions in the central nervous system. The cyclic activation of these channels influences neurotransmitter release, neuron excitability, gene transcription and plasticity, providing distinct brain areas with unique physiological and pharmacological response. A growing body of data has implicated ion channels in the susceptibility or pathogenesis of psychiatric diseases. Indeed, population studies support the association of polymorphisms in calcium and potassium channels with the genetic risk for bipolar disorders or schizophrenia. Moreover, point mutations in calcium, sodium and potassium channel genes have been identified in some childhood developmental disorders. Finally, antibodies against potassium channel complexes occur in a series of autoimmune psychiatric diseases. Here we report recent studies assessing the role of calcium, sodium and potassium channels in bipolar disorder, schizophrenia and autism spectrum disorders, and briefly summarize promising pharmacological strategies targeted on ion channels for the therapy of mental illness and related genetic tests.

  6. Ion channeling

    International Nuclear Information System (INIS)

    Erramli, H.; Blondiaux, G.

    1994-01-01

    Channeling phenomenon was predicted, many years ago, by stark. The first channeling experiments were performed in 1963 by Davies and his coworkers. Parallely Robinson and Oen have investigated this process by simulating trajectories of ions in monocrystals. This technique has been combined with many methods like Rutherford Backscattering Spectrometry (R.B.S.), Particles Induced X-rays Emission (P.I.X.E) and online Nuclear Reaction (N.R.A.) to localize trace elements in the crystal or to determine crystalline quality. To use channeling for material characterization we need data about the stopping power of the incident particle in the channeled direction. The ratios of channeled to random stopping powers of silicon for irradiation in the direction have been investigated and compared to the available theoretical results. We describe few applications of ion channeling in the field of materials characterization. Special attention is given to ion channeling combined with Charged Particle Activation Analysis (C.P.A.A.) for studying the behaviour of oxygen atoms in Czochralski silicon lattices under the influence of internal gettering and in different gaseous atmospheres. Association between ion channeling and C.P.A.A was also utilised for studying the influence of the growing conditions on concentration and position of carbon atoms at trace levels in the MOVPE Ga sub (1-x) Al sub x lattice. 6 figs., 1 tab., 32 refs. (author)

  7. Report of sodium cavitation

    International Nuclear Information System (INIS)

    Murai, Hitoshi; Shima, Akira; Oba, Toshisaburo; Kobayashi, Ryoji; Hashimoto, Hiroyuki

    1975-01-01

    The damage of components for LMFBRs due to sodium cavitation is serious problem. This report summarizes the following items, (1) mechanism of the incipience of sodium cavitation, (2) damage due to sodium cavitation, (3) detection method for sodium cavitation, and (4) estimation method for sodium cavitation by the comparison with water cavitation. Materials were collected from the reports on liquid metal cavitation, sodium cavitation and water cavitation published from 1965 to now. The mechanism of the incipience of sodium cavitation cavitation parameters (mean location, distributed amount or occurrence aspect and stability), experiment of causing cavitation with Venturi tube, and growth of bubbles within superheated sodium. The sodium cavitation damage was caused by magnetostriction vibration method and with Venturi tube. The state of damage was investigated with the cavitation performance of a sodium pump, and the damage was examined in view of the safety of LMFBR plants. Sodium cavitation was detected with acoustic method, radiation method, and electric method. The effect of physical property of liquid on incipient cavitation was studied. These are thermodynamic effect based on quasistatic thermal equilibrium condition and the effect of the physical property of liquid based on bubble dynamics. (Iwase, T.)

  8. Sodium safety manual

    International Nuclear Information System (INIS)

    Hayes, D.J.; Gardiner, R.L.

    1980-09-01

    The sodium safety manual is based upon more than a decade of experience with liquid sodium at Berkeley Nuclear Laboratories (BNL). It draws particularly from the expertise and experience developed in the course of research work into sodium fires and sodium water reactions. It draws also on information obtained from the UKAEA and other sodium users. Many of the broad principles will apply to other Establishments but much of the detail is specific to BNL and as a consequence its application at other sites may well be limited. Accidents with sodium are at best unpleasant and at worst lethal in an extremely painful way. The object of this manual is to help prevent sodium accidents. It is not intended to give detailed advice on specific precautions for particular situations, but rather to set out the overall strategy which will ensure that sodium activities will be pursued safely. More detail is generally conveyed to staff by the use of local instructions known as Sodium Working Procedures (SWP's) which are not reproduced in this manual although a list of current SWP's is included. Much attention is properly given to the safe design and operation of larger facilities; nevertheless evidence suggests that sodium accidents most frequently occur in small-scale work particularly in operations associated with sodium cleaning and special care is needed in all such cases. (U.K.)

  9. Channel box

    International Nuclear Information System (INIS)

    Tanabe, Akira.

    1993-01-01

    In a channel box of a BWR type reactor, protruding pads are disposed in axial position on the lateral side of a channel box opposing to a control rod and facing the outer side portion of the control rod in a reactor core loaded state. In the initial loading stage of fuel assemblies, channel fasteners and spacer pads are abutted against each other in the upper portion between the channel boxes sandwiching the control rod therebetween. Further, in the lower portion, a gap as a channel for the movement of the control rod is ensured by the support of fuel support metals. If the channel box is bent toward the control rod along with reactor operation, the pads are abutted against each other to always ensure the gap through which the control rod can move easily. Further, when the pads are brought into contact with each other, the bending deformation of the channel box is corrected by urging to each other. Thus, the control rod can always be moved smoothly to attain reactor safety operation. (N.H.)

  10. Dialysate sodium and sodium gradient in maintenance hemodialysis: a neglected sodium restriction approach?

    OpenAIRE

    Munoz Mendoza, Jair; Sun, Sumi; Chertow, Glenn M.; Moran, John; Doss, Sheila; Schiller, Brigitte

    2011-01-01

    Background. A higher sodium gradient (dialysate sodium minus pre-dialysis plasma sodium) during hemodialysis (HD) has been associated with sodium loading; however, its role is not well studied. We hypothesized that a sodium dialysate prescription resulting in a higher sodium gradient is associated with increases in interdialytic weight gain (IDWG), blood pressure (BP) and thirst.

  11. Single versus Serial Measurements of Neuron-Specific Enolase and Prediction of Poor Neurological Outcome in Persistently Unconscious Patients after Out-Of-Hospital Cardiac Arrest - A TTM-Trial Substudy

    DEFF Research Database (Denmark)

    Wiberg, Sebastian; Hassager, Christian; Stammet, Pascal

    2017-01-01

    were included from sites participating in the TTM-trial biobank sub study. NSE was measured at 24, 48 and 72 hours after ROSC and follow-up was concluded after 180 days. The primary end point was poor neurological function or death defined by a cerebral performance category score (CPC-score) of 3 to 5...... of the biomarker neuron-specific enolase (NSE) in combination with other predictors of outcome in patients admitted after out-of-hospital cardiac arrest (OHCA). This study sought to investigate the ability of NSE to predict poor outcome in patients remaining unconscious at day three after OHCA. In addition....... RESULTS: A total of 685 (73%) patients participated in the study. At day three after OHCA 63 (9%) patients had died and 473 (69%) patients were not awake. In these patients, a single NSE measurement at 48 hours predicted poor outcome with an area under the receiver operating characteristics curve (AUC...

  12. Surface channeling

    International Nuclear Information System (INIS)

    Sizmann, R.; Varelas, C.

    1976-01-01

    There is experimental evidence that swift light ions incident at small angles towards single crystalline surfaces can lose an appreciable fraction of their kinetic energy during reflection. It is shown that these projectiles penetrate into the bulk surface region of the crystal. They can travel as channeled particles along long paths through the solid (surface channeling). The angular distribution and the depth history of the re-emerged projectiles are investigated by computer simulations. A considerable fraction of the penetrating projectiles re-emerges from the crystal with constant transverse energy if the angle of incidence is smaller than the critical angle for axial channeling. Analytical formulae are derived based on a diffusion model for surface channeling. A comparison with experimental data exhibits the relevance of the analytical solutions. (Auth.)

  13. Spark Channels

    Energy Technology Data Exchange (ETDEWEB)

    Haydon, S. C. [Department of Physics, University of New England, Armidale, NSW (Australia)

    1968-04-15

    A brief summary is given of the principal methods used for initiating spark channels and the various highly time-resolved techniques developed recently for studies with nanosecond resolution. The importance of the percentage overvoltage in determining the early history and subsequent development of the various phases of the growth of the spark channel is discussed. An account is then given of the recent photographic, oscillographic and spectroscopic investigations of spark channels initiated by co-axial cable discharges of spark gaps at low [{approx} 1%] overvoltages. The phenomena observed in the development of the immediate post-breakdown phase, the diffuse glow structure, the growth of the luminous filament and the final formation of the spark channel in hydrogen are described. A brief account is also given of the salient features emerging from corresponding studies of highly overvolted spark gaps in which the spark channel develops from single avalanche conditions. The essential differences between the two types of channel formation are summarized and possible explanations of the general features are indicated. (author)

  14. Solubilities of sodium nitrate, sodium nitrite, and sodium aluminate in simulated nuclear waste

    International Nuclear Information System (INIS)

    Reynolds, D.A.; Herting, D.L.

    1984-09-01

    Solubilities were determined for sodium nitrate, sodium nitrite, and sodium aluminate in synthetic nuclear waste liquor. Solubilities were determined as a function of temperature and solution composition (concentrations of sodium hydroxide, sodium nitrate, sodium nitrite, and sodium aluminate). Temperature had the greatest effect on the solubilities of sodium nitrate and sodium nitrite and a somewhat lesser effect on sodium aluminate solubility. Hydroxide had a great effect on the solubilities of all three salts. Other solution components had minor effects. 2 references, 8 figures, 11 tables

  15. Sodium aerosol recovering device

    International Nuclear Information System (INIS)

    Fujimori, Koji; Ueda, Mitsuo; Tanaka, Kazuhisa.

    1997-01-01

    A main body of a recovering device is disposed in a sodium cooled reactor or a sodium cooled test device. Air containing sodium aerosol is sucked into the main body of the recovering device by a recycling fan and introduced to a multi-staged metal mesh filter portion. The air about against each of the metal mesh filters, and the sodium aerosol in the air is collected. The air having a reduced sodium aerosol concentration circulates passing through a recycling fan and pipelines to form a circulation air streams. Sodium aerosol deposited on each of the metal mesh filters is scraped off periodically by a scraper driving device to prevent clogging of each of the metal filters. (I.N.)

  16. [Sodium intake during pregnancy].

    Science.gov (United States)

    Delemarre, F M; Franx, A; Knuist, M; Steegers, E A

    1999-10-23

    International studies have yielded contradictory results on efficacy of a sodium-restricted diet during pregnancy in preventing and curing hypertension of pregnancy. In the Netherlands three studies have been performed to investigate the value of dietary sodium restriction in pregnancy; they concerned epidemiology, prevention and treatment. Midwives often prescribed this dietary intervention. Urinary sodium excretion was not related to blood pressure changes in pregnancy. Dietary sodium restriction from the third month of pregnancy onwards did not reduce the incidence of pregnancy-induced hypertension. Maternal side effects were a decreased intake of nutrients, decreased maternal weight gain, lowered plasma volume and stimulation of the renin-angiotensin-aldosterone system. A dietary sodium restriction in women with early symptoms of pregnancy-induced hypertension showed no therapeutic effect on blood pressure. There is no place for dietary sodium restriction in the prevention or treatment of hypertension in pregnancy.

  17. Sodium fire protection

    International Nuclear Information System (INIS)

    Raju, C.; Kale, R.D.

    1979-01-01

    Results of experiments carried out with sodium fires to develop extinguishment techniques are presented. Characteristics, ignition temperature, heat evolution and other aspects of sodium fires are described. Out of the powders tested for extinguishment of 10 Kg sodium fires, sodium bi-carbonate based dry chemical powder has been found to be the best extinguisher followed by large sized vermiculite and then calcium carbonate powders distributed by spray nozzles. Powders, however, do not extinguish large fires effectively due to sodium-concrete reaction. To control large scale fires in a LMFBR, collection trays with protective cover have been found to cause oxygen starvation better than flooding with inert gas. This system has an added advantage in that there is no damage to the sodium facilities as has been in the case of powders which often contain chlorine compounds and cause stress corrosion cracking. (M.G.B.)

  18. Electron scattering from sodium at intermediate energies

    International Nuclear Information System (INIS)

    Mitroy, J.; McCarthy, I.E.

    1986-10-01

    A comprehensive comparison is made between theoretical calculations and experimental data for intermediate energy (≥ 10 eV) electron scattering from sodium vapour. The theoretical predictions of coupled-channels calculations (including one, two or four channels) do not agree with experimental values of the differential cross sections for elastic scattering or the resonant 3s to 3p excitation. Increasingly-more-sophisticated calculations, incorporating electron correlations in the target states, and also including core-excited states in the close-coupling expansion, are done at a few selected energies in an attempt to isolate the cause of the discrepancies between theory and experiment. It is found that these more-sophisticated calculations give essentially the same results as the two- and four-channel calculations using Hartree-Fock wavefunctions. Comparison of the sodium high-energy elastic differential cross sections with those of neon suggests that the sodium differential cross section experiments may suffer from systematic errors. There is also disagreement, at the higher energies, between theoretical values for the scattering parameters and those that are derived from laser-excited superelastic scattering and electron photon coincidence experiments. When allowance is made for the finite acceptance angle of the electron spectrometers used in the experiments by convoluting the theory with a function representing the distribution of electrons entering the electron spectrometer it is found that the magnitudes of the differences between theory and experiment are reduced

  19. Sodium fire suppression

    Energy Technology Data Exchange (ETDEWEB)

    Malet, J C [DSN/SESTR, Centre de Cadarache, Saint-Paul-lez-Durance (France)

    1979-03-01

    Ignition and combustion studies have provided valuable data and guidelines for sodium fire suppression research. The primary necessity is to isolate the oxidant from the fuel, rather than to attempt to cool the sodium below its ignition temperature. Work along these lines has led to the development of smothering tank systems and a dry extinguishing powder. Based on the results obtained, the implementation of these techniques is discussed with regard to sodium fire suppression in the Super-Phenix reactor. (author)

  20. Sodium fire suppression

    International Nuclear Information System (INIS)

    Malet, J.C.

    1979-01-01

    Ignition and combustion studies have provided valuable data and guidelines for sodium fire suppression research. The primary necessity is to isolate the oxidant from the fuel, rather than to attempt to cool the sodium below its ignition temperature. Work along these lines has led to the development of smothering tank systems and a dry extinguishing powder. Based on the results obtained, the implementation of these techniques is discussed with regard to sodium fire suppression in the Super-Phenix reactor. (author)

  1. Sodium fill of FFTF

    International Nuclear Information System (INIS)

    Waldo, J.B.; Greenwell, R.K.; Keasling, T.A.; Collins, J.R.; Klos, D.B.

    1980-02-01

    With construction of the Fast Flux Test Facility (FFTF) completed, the first major objective in the startup program was to fill the sodium systems. A sodium fill sequence was developed to match construction completion, and as systems became available, they were inerted, preheated, and filled with sodium. The secondary sodium systems were filled first while dry refueling system testing was in progress in the reactor vessel. The reactor vessel and the primary loops were filled last. This paper describes the methods used and some of the key results achieved for this major FFTF objective

  2. Fires of sodium installations

    International Nuclear Information System (INIS)

    Hajek, L.; Tlalka, R.

    1984-01-01

    A survey is presented of the literature dealing with fires of sodium installations between 1974 and 1981. Also described are three experimental fires of ca 50 kg of sodium in an open area, monitored by UJV Rez. The experimental conditions of the experiments are described and a phenomenological description is presented of the course of the fires. The experiments showed a relationship between wind velocity in the area surrounding the fire and surface temperature of the sodium flame. Systems analysis methods were applied to sodium area, spray and tube fires. (author)

  3. Modeling and Validation of Sodium Plugging for Heat Exchangers in Sodium-cooled Fast Reactor Systems

    Energy Technology Data Exchange (ETDEWEB)

    Ferroni, Paolo [Westinghouse Electric Company LLC, Cranberry Township, PA (United States). Global Technology Development; Tatli, Emre [Westinghouse Electric Company LLC, Cranberry Township, PA (United States); Czerniak, Luke [Westinghouse Electric Company LLC, Cranberry Township, PA (United States); Sienicki, James J. [Argonne National Lab. (ANL), Argonne, IL (United States); Chien, Hual-Te [Argonne National Lab. (ANL), Argonne, IL (United States); Yoichi, Momozaki [Argonne National Lab. (ANL), Argonne, IL (United States); Bakhtiari, Sasan [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-06-29

    The project “Modeling and Validation of Sodium Plugging for Heat Exchangers in Sodium-cooled Fast Reactor Systems” was conducted jointly by Westinghouse Electric Company (Westinghouse) and Argonne National Laboratory (ANL), over the period October 1, 2013- March 31, 2016. The project’s motivation was the need to provide designers of Sodium Fast Reactors (SFRs) with a validated, state-of-the-art computational tool for the prediction of sodium oxide (Na2O) deposition in small-diameter sodium heat exchanger (HX) channels, such as those in the diffusion bonded HXs proposed for SFRs coupled with a supercritical CO2 (sCO2) Brayton cycle power conversion system. In SFRs, Na2O deposition can potentially occur following accidental air ingress in the intermediate heat transport system (IHTS) sodium and simultaneous failure of the IHTS sodium cold trap. In this scenario, oxygen can travel through the IHTS loop and reach the coldest regions, represented by the cold end of the sodium channels of the HXs, where Na2O precipitation may initiate and continue. In addition to deteriorating HX heat transfer and pressure drop performance, Na2O deposition can lead to channel plugging especially when the size of the sodium channels is small, which is the case for diffusion bonded HXs whose sodium channel hydraulic diameter is generally below 5 mm. Sodium oxide melts at a high temperature well above the sodium melting temperature such that removal of a solid plug such as through dissolution by pure sodium could take a lengthy time. The Sodium Plugging Phenomena Loop (SPPL) was developed at ANL, prior to this project, for investigating Na2O deposition phenomena within sodium channels that are prototypical of the diffusion bonded HX channels envisioned for SFR-sCO2 systems. In this project, a Computational Fluid Dynamic (CFD) model capable of simulating the thermal-hydraulics of the SPPL test

  4. A selectivity filter at the intracellular end of the acid-sensing ion channel pore

    DEFF Research Database (Denmark)

    Lynagh, Timothy; Flood, Emelie; Boiteux, Céline

    2017-01-01

    Increased extracellular proton concentrations during neurotransmission are converted to excitatory sodium influx by acid-sensing ion channels (ASICs). 10-fold sodium/potassium selectivity in ASICs has long been attributed to a central constriction in the channel pore, but experimental verificatio...... at the "GAS belt" in the central constriction. Instead, we identified a band of glutamate and aspartate side chains at the lower end of the pore that enables preferential sodium conduction....

  5. Theoretical Study of Sodium-Water Surface Reaction Mechanism

    Science.gov (United States)

    Kikuchi, Shin; Kurihara, Akikazu; Ohshima, Hiroyuki; Hashimoto, Kenro

    Computational study of the sodium-water reaction at the gas (water) - liquid (sodium) interface has been carried out using the ab initio (first-principle) method. A possible reaction channel has been identified for the stepwise OH bond dissociations of a single water molecule. The energetics including the binding energy of a water molecule on the sodium surface, the activation energies of the bond cleavages, and the reaction energies, have been evaluated, and the rate constants of the first and second OH bond-breakings have been compared. It was found that the estimated rate constant of the former was much larger than the latter. The results are the basis for constructing the chemical reaction model used in a multi-dimensional sodium-water reaction code, SERAPHIM, being developed by Japan Atomic Energy Agency (JAEA) toward the safety assessment of the steam generator (SG) in a sodium-cooled fast reactor (SFR).

  6. Theoretical study of sodium-water surface reaction mechanism

    International Nuclear Information System (INIS)

    Kikuchi, Shin; Kurihara, Akikazu; Ohshima, Hiroyuki; Hashimoto, Kenro

    2012-01-01

    Computational study of the sodium-water reaction at the gas (water) - liquid (sodium) interface has been carried out using the ab initio (first-principle) method. A possible reaction channel has been identified for the stepwise OH bond dissociations of a single water molecule. The energetics including the binding energy of a water molecule on the sodium surface, the activation energies of the bond cleavages, and the reaction energies, have been evaluated, and the rate constants of the first and second OH bond-breakings have been compared. It was found that the estimated rate constant of the former was much larger than the latter. The results are the basis for constructing the chemical reaction model used in a multi-dimensional sodium-water reaction code, SERAPHIM, being developed by Japan Atomic Energy Agency (JAEA) toward the safety assessment of the steam generator (SG) in a sodium-cooled fast reactor (SFR). (author)

  7. Visibility in sodium fume

    International Nuclear Information System (INIS)

    Hughes, G.W.; Anderson, N.R.

    1971-01-01

    The appearance of sodium fume of unknown concentration and the effects of short term exposure on unprotected workers is described. The molecular extinction coefficient of sodium fume is calculated from which light transmission data, and a rapid method for the estimation of the fume concentration is proposed. (author)

  8. Sodium outleakage detection

    International Nuclear Information System (INIS)

    Casselman, C.

    1979-01-01

    Effective detection of outleakage from sodium facilities permits timely intervention capable of limiting the consequences of such leakage. Two types of detection systems are described: local and overall detection. The use of two independent systems in sodium facilities is recommended. (author)

  9. Annular sodium flowsensor

    International Nuclear Information System (INIS)

    Kaiser, W.C.; Brewer, J.; Forster, G.A.

    1983-01-01

    This paper describes a unique eddy-current type liquid sodium flowsensor, designed as a joint effort between Argonne National Laboratory and Kaman Instrumentation Corp. Test results are included for operation of the flowsensor mounted on a sodium test loop whose configuration simulates the actual operating conditions, except for the magnetic field of the ALIP

  10. MARKETING CHANNELS

    Directory of Open Access Journals (Sweden)

    Ljiljana Stošić Mihajlović

    2014-07-01

    Full Text Available Marketing channel is a set of entities and institutions, completion of distribution and marketing activities, attend the efficient and effective networking of producers and consumers. Marketing channels include the total flows of goods, money and information taking place between the institutions in the system of marketing, establishing a connection between them. The functions of the exchange, the physical supply and service activities, inherent in the system of marketing and trade. They represent paths which products and services are moving after the production, which will ultimately end up buying and eating by the user.

  11. Total-body sodium and sodium excess

    International Nuclear Information System (INIS)

    Aloia, J.F.; Cohn, S.H.; Abesamis, C.; Babu, T.; Zanzi, I.; Ellis, K.

    1980-01-01

    Total-body levels of sodium (TBNa), chlorine (TBCI), calcium (TBCa), and potassium (TBK) were measured by neutron activation and analysis of results by whole body counting in 66 postmenopausal women. The relationship between TBNa, and TBCl, TBK, and TBCa on the one hand, and height and weight on the other, were found to compare with those previously reported. The hypothesis that TBNa and TBCl are distributed normally could not be rejected. The sodium excess (Na/sub es/) is defined as the sodium that is present in excess of that associated with the extracellular fluid (chlorine) space; the Na/sub es/ approximates nonexchangeable bone sodium. In these 66 postmenopausal women, and in patients with different endocrinopathies previously described, the values on Na/sub es/ did not differ from the normal values except in the thyrotoxicosis patients, where they were decreased. A close relationship between Na/sub es/ and TBCa was maintained in the endocrinopathies studied. This relationship was found in conditions accompanied by either an increment or a loss of skeletal mass. It appears that the NA/sub es/ value is primarily dependent upon the calcium content of bone

  12. Sodium Carbonate is Saltier Than Sodium Chloride to Sodium-Depleted Rats.

    Science.gov (United States)

    St John, Steven J; McBrayer, Anya M; Krauskopf, Erin E

    2017-10-01

    In a series of behavioral experiments in the 1960s, G.R. Morrison identified several unique features of the taste of Na2CO3 to rats; namely, it is 1) considerably more intense than NaCl at isomolar concentrations, 2) avoided at 10 times lower concentrations than NaCl to thirsty rats, 3) preferred at 10 times lower concentrations than NaCl in sodium-depleted rats. He also demonstrated its qualitatively similarity to NaCl. In Experiment 1, we confirmed and extended many of Morrison's observations. Rats were injected with furosemide on 3 occasions to stimulate a sodium appetite. After each depletion, rats were given a brief-access taste test in a lickometer presenting, in random order, water and 7 concentrations of salt. One test used NaCl (0.028-0.89 M, quarter log steps), another used Na2CO3, and the third used Na2CO3, but at a tenfold lower concentration range (0.0028-0.089 M). Rats licked NaCl in an inverted-U shaped concentration-response function peaking at 0.158-0.281 M. As Morrison's results predicted, rats licked Na2CO3 in nearly identical fashion, but at a tenfold lower concentration range (peak at 0.0158-0.028 M). In a second experiment, furosemide-treated rats were repeatedly tested with the lower Na2CO3 range but mixed in the epithelial sodium channel blocker amiloride at various concentrations (3-300 μM, half log steps). Amiloride reduced licking for Na2CO3 and shifted the peak response rightward up to about half a log unit. Thus, this "super-saltiness" of Na2CO3 to rats is at least partly amiloride-dependent. © The Author 2017. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  13. Influence of Pyrethroid Insecticides on Sodium and Calcium Influx in Neocortical Neurons

    Science.gov (United States)

    Pyrethroid insecticides bind to voltage-gated sodium channels and modify their gating kinetics, thereby disrupting neuronal function. Using murine neocortical neurons in primary culture, we have compared the ability of 11 structurally diverse pyrethroid insecticides to evoke Na+ ...

  14. Additivity of Pyrethroid Actions on Sodium Influx in Cortical Neurons in Cerebrocortical Neurons in Primary Culture

    Science.gov (United States)

    BACKGROUND: Pyrethroid insecticides bind to voltage-gated sodium channels and modify their gating kinetics, thereby disrupting neuronal function. Although previous work has tested the additivity of pyrethroids in vivo, this has not been assessed directly at the primary molecular ...

  15. El litio y su relación con la acuaporina-2 y el canal de sodio ENaC Lithium and its relation with the epithelial sodium channel and aquaporin-2

    Directory of Open Access Journals (Sweden)

    Luciano Galizia

    2012-04-01

    the collecting duct's principal cells through the epithelial Na channel (ENaC located on the apical side of the cells. Polyuria, renal tubular acidosis and chronic renal failure are the most frequent adverse effects of lithium after 10-20 years of treatment and these alterations can reach to a vasopressin nonresponding form of diabetes insipidus entity called nephrogenic diabetes insipidus. It is believed that the molecular mechanisms of these renal changes are related to a reduction in the number of aquaporin-2 inserted in the apical membrane of the cells. The causes of this are complex. Lithium is a powerful inhibitor of the enzyme glycogen synthase kinase 3β and this is associated with a lower activity of adenylate cyclase with a reduction in the cAMP levels inside of the cells. The latter may interfere with the synthesis of aquaporin-2 and also with the traffic of these molecules from the subapical site to membrane promoting the impairment of water reabsorption in the distal part of the kidney.

  16. Mechanosensitive Piezo Channels in the Gastrointestinal Tract.

    Science.gov (United States)

    Alcaino, C; Farrugia, G; Beyder, A

    2017-01-01

    Sensation of mechanical forces is critical for normal function of the gastrointestinal (GI) tract and abnormalities in mechanosensation are linked to GI pathologies. In the GI tract there are several mechanosensitive cell types-epithelial enterochromaffin cells, intrinsic and extrinsic enteric neurons, smooth muscle cells and interstitial cells of Cajal. These cells use mechanosensitive ion channels that respond to mechanical forces by altering transmembrane ionic currents in a process called mechanoelectrical coupling. Several mechanosensitive ionic conductances have been identified in the mechanosensory GI cells, ranging from mechanosensitive voltage-gated sodium and calcium channels to the mechanogated ion channels, such as the two-pore domain potassium channels K2P (TREK-1) and nonselective cation channels from the transient receptor potential family. The recently discovered Piezo channels are increasingly recognized as significant contributors to cellular mechanosensitivity. Piezo1 and Piezo2 are nonselective cationic ion channels that are directly activated by mechanical forces and have well-defined biophysical and pharmacologic properties. The role of Piezo channels in the GI epithelium is currently under investigation and their role in the smooth muscle syncytium and enteric neurons is still not known. In this review, we outline the current state of knowledge on mechanosensitive ion channels in the GI tract, with a focus on the known and potential functions of the Piezo channels. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Channel Power in Multi-Channel Environments

    NARCIS (Netherlands)

    M.G. Dekimpe (Marnik); B. Skiera (Bernd)

    2004-01-01

    textabstractIn the literature, little attention has been paid to instances where companies add an Internet channel to their direct channel portfolio. However, actively managing multiple sales channels requires knowing the customers’ channel preferences and the resulting channel power. Two key

  18. [Channels: a new way to revisit pathology].

    Science.gov (United States)

    Fournier, Emmanuel

    2014-02-01

    Many "essential" diseases that manifest themselves in the form of crises or fits (epilepsies, episodic ataxia, periodic paralyses, myotonia, heart rhythm disorders, etc.) are due to ionic channel dysfunction and are thus referred to as "channelopathies". Some of these disorders are congenital, due to mutations of genes encoding channel subunits, while others result from toxic, immune or hormonal disturbances affecting channelfunction. Channelopathies take on a wide variety of clinical forms, depending on the type of channel (sodium, potassium, calcium, chloride...) and the type of dysfunction (loss or gain of function). Some apparently unrelated diseases affecting distinct organs are due to a similar dysfunction of the same channel, revealing unsuspected relationships between organs and between medical specialties. In addition, a given syndrome can be caused by distinct channel dysfunctions. This provides new opportunities for diferential diagnosis and specific correction of the causal defects, although some treatments find applications across multiple medical specialties.

  19. Methodology for Extraction of Remaining Sodium of Used Sodium Containers

    International Nuclear Information System (INIS)

    Jung, Minhwan; Kim, Jongman; Cho, Youngil; Jeong, Jiyoung

    2014-01-01

    Sodium used as a coolant in the SFR (Sodium-cooled Fast Reactor) reacts easily with most elements due to its high reactivity. If sodium at high temperature leaks outside of a system boundary and makes contact with oxygen, it starts to burn and toxic aerosols are produced. In addition, it generates flammable hydrogen gas through a reaction with water. Hydrogen gas can be explosive within the range of 4.75 vol%. Therefore, the sodium should be handled carefully in accordance with standard procedures even though there is a small amount of target sodium remainings inside the containers and drums used for experiment. After the experiment, all sodium experimental apparatuses should be dismantled carefully through a series of draining, residual sodium extraction, and cleaning if they are no longer reused. In this work, a system for the extraction of the remaining sodium of used sodium drums has been developed and an operation procedure for the system has been established. In this work, a methodology for the extraction of remaining sodium out of the used sodium container has been developed as one of the sodium facility maintenance works. The sodium extraction system for remaining sodium of the used drums was designed and tested successfully. This work will contribute to an establishment of sodium handling technology for PGSFR. (Prototype Gen-IV Sodium-cooled Fast Reactor)

  20. Clinical significance of combined determination of serum neuron-specific enolase (NSE), tumor necrosis factor-α (TNF-α) and lipid-associated sialic acid (LSA) in patients with lung cancer

    International Nuclear Information System (INIS)

    Wu Wei; Yao Dengfu; Qiu Liwei; Wu Xinghua

    2003-01-01

    Objective: To explore the expression and the diagnostic value of determining serum neuron-specific enolase (NSE), tumor necrosis factor-α (TNF-α) and lipid-associated sialic acid (LSA) in patients with lung cancer. Methods: The concentrations of NSE, TNF-α and LSA were measured in 78 patients with lung cancer and 32 patients with benign lung diseases as well as 109 controls by enzymelinked immunosorbent assay (ELISA) and chemical assay respectively. Results: The levels of NSE (19.78 ± 12.10 ng/ml), TNF-α (135.64 ± 49.01 pg/ml) and LSA (106 ± 0.31 ng/ml) were significantly higher in patients with lung cancer than those in patients with benign lung diseases (NSE 7.56 ± 3.41 ng/ml, TNF-α 84.70 ± 24.89 pg/ml, LSA 0.78 ± 0.18 mg/ml) and controls (NSE 8.01 ± 2.81 ng/ml, TNF-α 71.25 ± 13.50 pg/ml, LSA 0.70 ± 0.13 ng/ml) (all p < 0.01). Conclusion: The present data suggest that the syntheses of NSE, TNF-α and LSA increase in patients with lung cancer and combined determination of NSE, TNF-α and LSA be helpful to diagnosis of lung cancer

  1. Sodium oxide aerosol filtration

    Energy Technology Data Exchange (ETDEWEB)

    Duverger de Cuy, G [DSN/SESTR, Centre de Cadarache, Saint-Paul-lez-Durance (France)

    1979-03-01

    In the scope of the sodium aerosol trapping research effort by the CEA/DSN, the retention capacity and yield were measured for very high efficiency fiberglass filters and several types of prefilters (cyclone agglomerator, fabric prefilters, water scrubbers). (author)

  2. Sodium oxide aerosol filtration

    International Nuclear Information System (INIS)

    Duverger de Cuy, G.

    1979-01-01

    In the scope of the sodium aerosol trapping research effort by the CEA/DSN, the retention capacity and yield were measured for very high efficiency fiberglass filters and several types of prefilters (cyclone agglomerator, fabric prefilters, water scrubbers). (author)

  3. Sodium distiller II

    International Nuclear Information System (INIS)

    Goncalves, A.C.; Castro, P.M. e; Torres, A.R.; Correa, S.M.

    1990-01-01

    A sodium distiller allows the evaluation of the sodium purity, contained in plants and circuits of Fast Reactors. The sodium distillers of the IEN Reactor's Department was developed initially as a prototype, for the testing of the distillation process and in a second step, as a equipment dedicated to attendance the operation of these circuits. This last one was build in stainless steel, with external heat, rotating crucible of nickel for four samples, purge system for pipe cleaning and a sight glass that permits the observation of the distillation during all the operation. The major advantage of this equipment is the short time to do a distillation operation, which permits its routine utilization. As a consequence of the development of the distillers and its auxiliary systems an important amount of new information was gathered concerning components and systems behaviour under high temperature, vacuum and sodium. (author)

  4. Sodium hypochlorite poisoning

    Science.gov (United States)

    ... that can cause choking and serious breathing problems. Symptoms of sodium hypochlorite poisoning may include: Burning, red eyes Chest pain Coma Coughing (from the fumes) Delirium Gagging sensation Low blood pressure Pain in the ...

  5. Liquid sodium oxygenmeter

    International Nuclear Information System (INIS)

    Jakes, D.; Fresl, M.; Svoboda, V.

    1979-02-01

    The results of test runs of two design varieties of liquid sodium oxygenmeter in sodium loops are described. The accuracy and sensitivity are discussed reached using this instrument within 1 and 10 p.p.m. of oxygen concentration. A change in the used reference system is proposed based on practical experiences and thermochemical calculations. Ceramic electrolyte corrosion is analysed and the possible interpretation of the corrosion effect on the galvanic cell electromotive force is suggested. (author)

  6. Too Much Sodium

    Centers for Disease Control (CDC) Podcasts

    This podcast is based on the February 2012 CDC Vital Signs report. Ninety percent of Americans age two and older eat too much sodium which can increase your risk for high blood pressure and often leads to heart disease and stroke, two leading causes of death in the US. Learn several small steps you can take to reduce the amount of sodium in your diet.

  7. Sodium fires and its extinguishment

    International Nuclear Information System (INIS)

    Mikhedov, V.G.

    1979-01-01

    The fire safety problems of NPP with sodium coolants in USSR are presented. The design of sodium reactors is made with premises with sodium coolants being hermetic and filled with nitrogen. Some engineering solutions of fire safety including design, elaboration and choice of construction and protection materials are presented. Some theoretical aspects of sodium burning are presented as well as methods of sodium fire extinguishing methods including the use of powder

  8. Renal tubular NHE3 is required in the maintenance of water and sodium chloride homeostasis.

    Science.gov (United States)

    Fenton, Robert A; Poulsen, Søren B; de la Mora Chavez, Samantha; Soleimani, Manoocher; Dominguez Rieg, Jessica A; Rieg, Timo

    2017-08-01

    The sodium/proton exchanger isoform 3 (NHE3) is expressed in the intestine and the kidney, where it facilitates sodium (re)absorption and proton secretion. The importance of NHE3 in the kidney for sodium chloride homeostasis, relative to the intestine, is unknown. Constitutive tubule-specific NHE3 knockout mice (NHE3 loxloxCre) did not show significant differences compared to control mice in body weight, blood pH or bicarbonate and plasma sodium, potassium, or aldosterone levels. Fluid intake, urinary flow rate, urinary sodium/creatinine, and pH were significantly elevated in NHE3 loxloxCre mice, while urine osmolality and GFR were significantly lower. Water deprivation revealed a small urinary concentrating defect in NHE3 loxloxCre mice on a control diet, exaggerated on low sodium chloride. Ten days of low or high sodium chloride diet did not affect plasma sodium in control mice; however, NHE3 loxloxCre mice were susceptible to low sodium chloride (about -4 mM) or high sodium chloride intake (about +2 mM) versus baseline, effects without differences in plasma aldosterone between groups. Blood pressure was significantly lower in NHE3 loxloxCre mice and was sodium chloride sensitive. In control mice, the expression of the sodium/phosphate co-transporter Npt2c was sodium chloride sensitive. However, lack of tubular NHE3 blunted Npt2c expression. Alterations in the abundances of sodium/chloride cotransporter and its phosphorylation at threonine 58 as well as the abundances of the α-subunit of the epithelial sodium channel, and its cleaved form, were also apparent in NHE3 loxloxCre mice. Thus, renal NHE3 is required to maintain blood pressure and steady-state plasma sodium levels when dietary sodium chloride intake is modified. Copyright © 2017 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.

  9. Development of sodium technology

    International Nuclear Information System (INIS)

    Hwang, Sung Tai; Nam, H. Y.; Choi, Y. D.

    2000-05-01

    The objective of present study is to produce the experimental data for development and verification of computer codes for development of LMR and to develop the preliminary technologies for the future large scale verification experiments. A MHD experimental test loop has been constructed for the quantitative analysis of the effect of magnetic field on the sodium flow and experiments are carried out for three EM pumps. The previous pressure drop correlations are evaluated using the experimental data obtained from the pressure drop experiment in a 19-pin fuel assembly with wire spacer. An dimensionless variable is proposed to describe the amplitude and frequency of the fluctuation of free surface using the experimental data obtained from free surface experimental apparatus and an empirical correlation is developed using this dimensionless variable. An experimental test loop is constructed to measure the flow characteristics in IHX shell side and the local pressure drop in fuel assembly, and to test the vibration behaviour of fuel pins due to flow induced vibration. The sodium two-phase flow measuring technique using the electromagnetic flowmeter is developed and the sodium differential pressure drop measuring technique using the method of direct contact of sodium and oil is established. The work on the analysis of sodium fire characteristics and produce data for vlidation of computer code is performed. Perfect reopen time of self plugged leak path was observed to be about 130 minutes after water leak initiation. Reopen shape of a specimen appeared to be double layer of circular type, and reopen size of this specimen surface was about 2mm diameter on sodium side. In small water leakage experiments, the following correlation equation about the reopen time between sodium temperature and initial leak rate was obtained, τ c = δ·g -0.83 ·10 (3570/T Na -3.34) , in 400-500 deg C of liquid sodium atmosphere. The characteristics of pressure propagation and gas flow, and

  10. Development of sodium technology

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Sung Tai; Nam, H Y; Choi, Y D [and others

    2000-05-01

    The objective of present study is to produce the experimental data for development and verification of computer codes for development of LMR and to develop the preliminary technologies for the future large scale verification experiments. A MHD experimental test loop has been constructed for the quantitative analysis of the effect of magnetic field on the sodium flow and experiments are carried out for three EM pumps. The previous pressure drop correlations are evaluated using the experimental data obtained from the pressure drop experiment in a 19-pin fuel assembly with wire spacer. An dimensionless variable is proposed to describe the amplitude and frequency of the fluctuation of free surface using the experimental data obtained from free surface experimental apparatus and an empirical correlation is developed using this dimensionless variable. An experimental test loop is constructed to measure the flow characteristics in IHX shell side and the local pressure drop in fuel assembly, and to test the vibration behaviour of fuel pins due to flow induced vibration. The sodium two-phase flow measuring technique using the electromagnetic flowmeter is developed and the sodium differential pressure drop measuring technique using the method of direct contact of sodium and oil is established. The work on the analysis of sodium fire characteristics and produce data for vlidation of computer code is performed. Perfect reopen time of self plugged leak path was observed to be about 130 minutes after water leak initiation. Reopen shape of a specimen appeared to be double layer of circular type, and reopen size of this specimen surface was about 2mm diameter on sodium side. In small water leakage experiments, the following correlation equation about the reopen time between sodium temperature and initial leak rate was obtained, {tau}{sub c} = {delta}{center_dot}g{sup -0.83}{center_dot}10{sup (3570/T{sub Na}-3.34)}, in 400-500 deg C of liquid sodium atmosphere. The characteristics

  11. Regulation of Na(+)/K(+)-ATPase by neuron-specific transcription factor Sp4: implication in the tight coupling of energy production, neuronal activity and energy consumption in neurons.

    Science.gov (United States)

    Johar, Kaid; Priya, Anusha; Wong-Riley, Margaret T T

    2014-02-01

    A major source of energy demand in neurons is the Na(+)/K(+)-ATPase pump that restores the ionic gradient across the plasma membrane subsequent to depolarizing neuronal activity. The energy comes primarily from mitochondrial oxidative metabolism, of which cytochrome c oxidase (COX) is a key enzyme. Recently, we found that all 13 subunits of COX are regulated by specificity (Sp) factors, and that the neuron-specific Sp4, but not Sp1 or Sp3, regulates the expression of key glutamatergic receptor subunits as well. The present study sought to test our hypothesis that Sp4 also regulates Na(+)/K(+)-ATPase subunit genes in neurons. By means of multiple approaches, including in silico analysis, electrophoretic mobility shift and supershift assays, chromatin immunoprecipitation, promoter mutational analysis, over-expression, and RNA interference studies, we found that Sp4, with minor contributions from Sp1 and Sp3, functionally regulate the Atp1a1, Atp1a3, and Atp1b1 subunit genes of Na(+)/K(+)-ATPase in neurons. Transcripts of all three genes were up-regulated by depolarizing KCl stimulation and down-regulated by the impulse blocker tetrodotoxin (TTX), indicating that their expression was activity-dependent. Silencing of Sp4 blocked the up-regulation of these genes induced by KCl, whereas over-expression of Sp4 rescued them from TTX-induced suppression. The effect of silencing or over-expressing Sp4 on primary neurons was much greater than those of Sp1 or Sp3. The binding sites of Sp factors on these genes are conserved among mice, rats and humans. Thus, Sp4 plays an important role in the transcriptional coupling of energy generation and energy consumption in neurons. © 2013 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  12. Channelling and electromagnetic radiation of channelling particles

    International Nuclear Information System (INIS)

    Kalashnikov, N.

    1983-01-01

    A brief description is presented of the channelling of charged particles between atoms in the crystal lattice. The specificities are discussed of the transverse motion of channelling particles as are the origin and properties of quasi-characteristic radiation of channelling particles which accompany transfers from one band of permissible energies of the transverse motion of channelling particles to the other. (B.S.)

  13. Sodium fire tests for investigating the sodium leak in Monju

    International Nuclear Information System (INIS)

    Seino, Hiroshi; Miyahara, Shinya; Miyake, Osamu; Tanabe, Hiromi

    1996-01-01

    As a part of the work for investigating the sodium leak accident which occurred in Monju on December 8, 1995, three tests, (1) sodium leak test, (2) sodium fire test-I, and (3) sodium fire test-II, were carried out at OEC/PNC. Main objectives of these tests are to confirm leak and burning behavior of sodium from the damaged thermometer, and effects of the sodium fire on integrity of the surrounding structure, etc. The main conclusions obtained from the tests are shown as below. 1) Average sodium leak rate obtained from the sodium leak test was about 50 g/sec. This was equivalent to the value estimated from level change in the sodium overflow tank in the Monju accident. 2) Observation from video cameras in the sodium fire tests revealed that in early stages of sodium leak, sodium dropped down out of the flexible tube of thermometer in drips. This dripping and burning were expanded in range as sodium splashed on the duct. 3) Though, in the sodium fire test-I, there was a decrease of about 1 mm at a thickness of the burning pan in the vicinity in just under in the leak point, there were completely no crack and failure. In the meantime, in the sodium fire test-II the six open holes were found in the floor liner. By this liner failure, the reaction between sodium and concrete might take place. At present, while the detailed evaluation on the sodium fire test-II has been mainly carried out, the investigation for clarifying the cause of the liner failure has been also carried out. (author)

  14. Channel Modeling

    Science.gov (United States)

    Schmitz, Arne; Schinnenburg, Marc; Gross, James; Aguiar, Ana

    For any communication system the Signal-to-Interference-plus-Noise-Ratio of the link is a fundamental metric. Recall (cf. Chapter 9) that the SINR is defined as the ratio between the received power of the signal of interest and the sum of all "disturbing" power sources (i.e. interference and noise). From information theory it is known that a higher SINR increases the maximum possible error-free transmission rate (referred to as Shannon capacity [417] of any communication system and vice versa). Conversely, the higher the SINR, the lower will be the bit error rate in practical systems. While one aspect of the SINR is the sum of all distracting power sources, another issue is the received power. This depends on the transmitted power, the used antennas, possibly on signal processing techniques and ultimately on the channel gain between transmitter and receiver.

  15. Channeling experiment

    International Nuclear Information System (INIS)

    Abelin, H.; Birgersson, L.; Widen, H.; Aagren, T.; Moreno, L.; Neretnieks, I.

    1990-07-01

    Channeling of water flow and tracer transport in real fractures in a granite body at Stripa have been investigated experimentally. The experimental site was located 360 m below the ground level. Two kinds of experiments were performed. In the single hole experiments, 20 cm diameter holes were drilled about 2.5 m into the rock in the plane of the fracture. Specially designed packers were used to inject water into the fracture in 5 cm intervals all along the fracture trace in the hole. The variation of the injection flowrates along the fracture were used to determine the transmissivity variations in the fracture plane. Detailed photographs were taken from inside the hole and the visual fracture aperture was compared with the injection flowrates in the same locations. Geostatistical methods were used to evaluate the results. Five holes were measured in great detail. In addition 7 holes were drilled and scanned by simpler packer systems. A double hole experiment was performed where two parallel holes were drilled in the same fracture plane at nearly 2 m distance. Pressure pulse tests were made between the holes in both directions. Tracers were injected in 5 locations in one hole and monitored for in many locations in the other hole. The single hole experiment and the double hole experiment show that most of the fracture planes are tight but that there are open sections which form connected channels over distances of at least 2 meters. It was also found in the double hole experiment that the investigated fracture was intersected by at least one fracture between the two holes which diverted a large amount of the injected tracers to several distant locations at the tunnel wall. (authours)

  16. The combustion of sodium

    International Nuclear Information System (INIS)

    Newman, R.N.

    1978-01-01

    The burning rates of sodium in the form of vapour jets, droplets, sprays and unconfined and confined pools have been reviewed. Attention has been paid to assessing the value of models in the various combustion modes. Additional models have been constructed for the descriptions of laminar and turbulent vapour jets, stationary droplets, forced convection over ambient pool fires together with correlations for peak pressures in confined pool environments. Where appropriate experiments with sodium have not been conducted, the likely behaviour is predicted by comparison with the burning of other fuels, particularly in the field of large free ambient fires. Some areas where further knowledge is required are highlighted. (author)

  17. Sodium cooled fast reactor

    Energy Technology Data Exchange (ETDEWEB)

    Hokkyo, N; Inoue, K; Maeda, H

    1968-11-21

    In a sodium cooled fast neutron reactor, an ultrasonic generator is installed at a fuel assembly hold-down mechanism positioned above a blanket or fission gas reservoir located above the core. During operation of the reactor an ultrsonic wave of frequency 10/sup 3/ - 10/sup 4/ Hz is constantly transmitted to the core to resonantly inject the primary bubble with ultrasonic energy to thereby facilitate its growth. Hence, small bubbles grow gradually to prevent the sudden boiling of sodium if an accident occurs in the cooling system during operation of the reactor.

  18. Too Much Sodium

    Centers for Disease Control (CDC) Podcasts

    2012-02-07

    This podcast is based on the February 2012 CDC Vital Signs report. Ninety percent of Americans age two and older eat too much sodium which can increase your risk for high blood pressure and often leads to heart disease and stroke, two leading causes of death in the US. Learn several small steps you can take to reduce the amount of sodium in your diet.  Created: 2/7/2012 by Centers for Disease Control and Prevention (CDC).   Date Released: 2/7/2012.

  19. Sodium fluxes in sweet pepper exposed to varying sodium concentrations

    NARCIS (Netherlands)

    Blom-Zandstra, M.; Vogelzang, S.A.; Veen, B.W.

    1998-01-01

    The sodium transport and distribution of sweet pepper (Capsicum annuum L.) under saline conditions were studied after transferring the plants to a sodium-free nutrient solution. Sodium stress up to 60 mM did not affect the growth of sweet pepper, as it appears able to counteract the unfavourable

  20. Sodium hydride precipitation in sodium cold traps

    International Nuclear Information System (INIS)

    McPheeters, C.C.; Raue, D.J.

    1979-10-01

    A series of experiments have been performed to test a calculational model for precipitation of NaH in sodium cold traps. The calculational model, called ACTMODEL, is a computer simulation that uses the system geometry and operating conditions as input to calculate a mass transfer coefficient and the distribution of NaH in a cold trap. The ACTMODEL was tested using an analytical cold trap (ACT) that is simple and essentially one-dimensional. The ACT flow and temperature profile may be controlled at any desired condition. The ACT was analyzed destructively after each test to measure the actual NaH distribution. Excellent agreement was obtained between the ACTMODEL simulations and the experiments

  1. Sodium hydride precipitation in sodium cold traps

    International Nuclear Information System (INIS)

    McPheeters, C.C.; Raue, D.J.

    1980-06-01

    A series of experiments have been performed to test a calculational model for precipitation of NaH in sodium cold traps. The calculational model, called ACTMODEL, is a computer simulation that uses the system geometry and operating conditions as input to calculate a mass-transfer coefficient and the distribution of NaH in a cold trap. The ACTMODEL was tested using an analytical cold trap (ACT) that is simple and essentially one-dimensional. The ACT flow and temperature profile can be controlled at any desired condition. The ACT was analyzed destructively after each test to measure the actual NaH distribution. Excellent agreement was obtained between the ACTMODEL simulations and the experiments. Mass-transfer coefficients ranging upward from 6 x 10 -5 m/s were measured in both packless and packed traps. As much as a fourfold increase in precipitation surface area was observed with increasing amount of NaH deposited. 11 figures, 2 tables

  2. Thermophysical properties of sodium

    International Nuclear Information System (INIS)

    Harant, M.

    1978-01-01

    Substitution, inverse and substitution inverse relations in form of regression polynomials were used in calculating saturation pressure and density for thermodynamic and transport properties determination of sodium. Program UNISOAUT/A3 was used in calculating regression polynomials coefficients. (J.P.)

  3. Extinction of sodium fires

    International Nuclear Information System (INIS)

    Malet, J.C.; Spagna, F.

    1989-01-01

    This paper presents how, starting from a knowledge of sodium ignition and burning, principles for extinction (smothering catch trays, leak recuperation systems, powders) can be developed. These techniques applied in Superphenix 1 and PEC reactors have been tested in the ESMERALDA experimental program which is a joint French/Italian project. (author)

  4. Decomposition of Sodium Tetraphenylborate

    International Nuclear Information System (INIS)

    Barnes, M.J.

    1998-01-01

    The chemical decomposition of aqueous alkaline solutions of sodium tetraphenylborate (NaTPB) has been investigated. The focus of the investigation is on the determination of additives and/or variables which influence NaTBP decomposition. This document describes work aimed at providing better understanding into the relationship of copper (II), solution temperature, and solution pH to NaTPB stability

  5. Sodium purification in Rapsodie

    International Nuclear Information System (INIS)

    Giraud, B.

    1968-01-01

    This report is one of a series of publications presenting the main results of tests carried out during the start-up of the first french fast neutron reactor: Rapsodie. The article presents the sodium purification techniques used in the reactor cooling circuits both from the constructional point of view and with respect to results obtained during the first years working. (author) [fr

  6. The medical sodium chloride

    International Nuclear Information System (INIS)

    Mirsaidov, U.M.

    2002-01-01

    In the institute was investigated the chemical composition of rock salt of some deposits of Tajikistan and was show the presence in it admixture of ions of Ca 2 + , Mg 2 + a nd SO 2 - a nd absence of heavy metals, ammonium salts, iron, potassium and arsenic. Was elaborated the fundamental instrument-technologic scheme of sodium chloride receiving

  7. Creep in sodium

    International Nuclear Information System (INIS)

    Charnock, W.; Cordwell, J.E.

    1978-03-01

    Available information on the creep of austenitic, ferritic and Alloy-800 type steels in liquid sodium is critically reviewed. Creep properties of stainless steels can be affected by element transfer and corrosion. At reactor structural component temperatures environmental effects are likely to be less important than changes due to thermal ageing. At high clad temperatures (700 0 C) decarburisation may cause the loss of strength and ductility in unstabilised steels while cavity formation may cause embrittlement in stabilised steels. The properties of Alloy 800 are, in some experiments, found to deteriorate while in others they are enhanced. This may be a consequence of the metallurgical complexity of the material or arise from the nature of the various techniques employed. Low alloy ferritic steels tend to decarburise in sodium at temperatures greater than 500 0 C and this leads to loss of strength and an increase in ductility. High alloy ferritics are immune to this effect and appear to be able to tolerate a degree of carburisation. Although intergranular cracking may be enhanced in liquid sodium the mechanical consequences are not significant and evidence for the existence of an embrittlement effect not associated with element transfer or corrosion is weak. Stress and strain may enhance element transfer at crack tips. However in real cracks the gettering or supply action of the crack faces conditions the chemistry of the cracks in sodium and protects the crack tip from element transfer. Thus creep crack extension rates should be independent of changes in bulk coolant chemistry. (author)

  8. Technology for sodium purity control

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Ji Young; Kim, B. H.; Kim, T. J. [Korea Atomic Energy Research Institute, Taejon (Korea)

    1999-10-01

    When sodium is used as heat transfer fluid, the plugging in coolant flow, the corrosion of structure material and the transfer of radioactive material caused by the impurities in sodium are worth considerable. Accordingly, these impurities must be monitored and controlled continuously by sodium purification devices in the heat transfer system which sodium is used as coolant. Sodium purification loop was constructed for the purpose of accumulating the technology for purity control of the coolant, developing and verifying further efficient instruments for sodium purification. The plugging meter and the cold trap is used as the implement for measuring and controlling the oxygen and the hydrogen, the main impurities in sodium coolant. They are capable of excellent performance as the implements which could detect and monitor the impurities to the concentration limit required for nuclear reactor. Sodium purification loop could be used variably according to the experimental purpose. 18 refs., 34 figs., 8 tabs. (Author)

  9. Slicing sodium from bakery products

    NARCIS (Netherlands)

    Noort, M.

    2012-01-01

    The need for sodium reduction in our diet is clear to consumers, dieticians and food manufacturers. As sodium concentration has a strengthening effect on gluten, sodium reduction decreases dough mixing tolerance, dough resistance and induces dough stickiness. In particular, the latter may cause

  10. Safety measuring for sodium handling

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Ji Young; Jeong, K C; Kim, T J; Kim, B H; Choi, J H

    2001-09-01

    This is the report for the safety measures of sodium handling. These contents are prerequisites for the development of sodium technology and thus the workers participate in sodium handling and experiments have to know them perfectly. As an appendix, the relating parts of the laws are presented.

  11. Functional modifications of acid-sensing ion channels by ligand-gated chloride channels.

    Directory of Open Access Journals (Sweden)

    Xuanmao Chen

    Full Text Available Together, acid-sensing ion channels (ASICs and epithelial sodium channels (ENaC constitute the majority of voltage-independent sodium channels in mammals. ENaC is regulated by a chloride channel, the cystic fibrosis transmembrane conductance regulator (CFTR. Here we show that ASICs were reversibly inhibited by activation of GABA(A receptors in murine hippocampal neurons. This inhibition of ASICs required opening of the chloride channels but occurred with both outward and inward GABA(A receptor-mediated currents. Moreover, activation of the GABA(A receptors modified the pharmacological features and kinetic properties of the ASIC currents, including the time course of activation, desensitization and deactivation. Modification of ASICs by open GABA(A receptors was also observed in both nucleated patches and outside-out patches excised from hippocampal neurons. Interestingly, ASICs and GABA(A receptors interacted to regulate synaptic plasticity in CA1 hippocampal slices. The activation of glycine receptors, which are similar to GABA(A receptors, also modified ASICs in spinal neurons. We conclude that GABA(A receptors and glycine receptors modify ASICs in neurons through mechanisms that require the opening of chloride channels.

  12. Sodium selectivity of Reissner's membrane epithelial cells

    Directory of Open Access Journals (Sweden)

    Kim Kyunghee X

    2011-02-01

    Full Text Available Abstract Background Sodium absorption by Reissner's membrane is thought to contribute to the homeostasis of the volume of cochlear endolymph. It was previously shown that the absorptive transepithelial current was blocked by amiloride and benzamil. The most commonly-observed target of these drugs is the epithelial sodium channel (ENaC, which is composed of the three subunits α-,β- and γ-ENaC. However, other less-selective cation channels have also been observed to be sensitive to benzamil and amiloride. The aim of this study was to determine whether Reissner's membrane epithelial cells could support parasensory K+ absorption via amiloride- and benzamil-sensitive electrogenic pathways. Results We determined the molecular and functional expression of candidate cation channels with gene array (GEO GSE6196, RT-PCR, and whole-cell patch clamp. Transcript expression analysis of Reissner's membrane detected no amiloride-sensitive acid-sensing ion channels (ASIC1a, ASIC2a, ASIC2b nor amiloride-sensitive cyclic-nucleotide gated channels (CNGA1, CNGA2, CNGA4, CNGB3. By contrast, α-,β- and γ-ENaC were all previously reported as present in Reissner's membrane. The selectivity of the benzamil-sensitive cation currents was observed in whole-cell patch clamp recordings under Cl--free conditions where cations were the only permeant species. The currents were carried by Na+ but not K+, and the permeability of Li+ was greater than that of Na+ in Reissner's membrane. Complete replacement of bath Na+ with the inpermeable cation NMDG+ led to the same inward current as with benzamil in a Na+ bath. Conclusions These results are consistent with the amiloride/benzamil-sensitive absorptive flux of Reissner's membrane mediated by a highly Na+-selective channel that has several key characteristics in common with αβγ-ENaC. The amiloride-sensitive pathway therefore absorbs only Na+ in this epithelium and does not provide a parasensory K+ efflux route from scala

  13. Specialists' meeting on sodium fires

    Energy Technology Data Exchange (ETDEWEB)

    Kozlov, F A; Kuznetsova, R I [eds.

    1989-07-01

    The four sessions of the meeting covered the following topics: 1. general approach to fast reactor safety, standards of fire safety, maximum design basis accidents for sodium leaks and fires, status of sodium fires in different countries; 2. physical and chemical processes during combustion of sodium and its interaction with structural and technological materials and methods for structural protection; 3. methods of sodium fires extinguishing and measures for localizing aerosol combustion products, organization of fire fighting procedures, instruction and training of fire personnel; 4. elimination of the consequences of sodium fires.

  14. Specialists' meeting on sodium fires

    International Nuclear Information System (INIS)

    Kozlov, F.A.; Kuznetsova, R.I.

    1989-01-01

    The four sessions of the meeting covered the following topics: 1. general approach to fast reactor safety, standards of fire safety, maximum design basis accidents for sodium leaks and fires, status of sodium fires in different countries; 2. physical and chemical processes during combustion of sodium and its interaction with structural and technological materials and methods for structural protection; 3. methods of sodium fires extinguishing and measures for localizing aerosol combustion products, organization of fire fighting procedures, instruction and training of fire personnel; 4. elimination of the consequences of sodium fires

  15. Development of Sodium Technology

    International Nuclear Information System (INIS)

    Choi, Jong Hyun; Nam, H. Y.; Kim, T. J.; Jeong, K. C.; Park, J. H.; Kim, B. H.; Jeong, J. Y.; Kim, J. M.; Choi, B. H.; Kim, B. S.

    2003-02-01

    The basic P and ID and fabrication method for IHTS simplification experiment were prepared for the experimental apparatus. In order to investigate the later phase of a SWR event, an experimental apparatus was designed and manufactured. The 620 data set have been obtained in the experiment of free surface fluctuation and an experimental correlation for the critical gas entertainment condition is additionally developed. For development of water into sodium leak detection technology, the properties from leak noises were extracted, and the tools for analyzing acoustic noises were constructed. The state-of-the-art on the flow and differential pressure measuring techniques in the piping system is investigated to develop new techniques which are applicable to high temperature sodium flow environment. The plan for the minimization of errors in temperature measurement was drawn up by analysing the error factors in temperature measurement. And the countermeasures for the minimization of errors in temperature measurement due to complex heat transfer were prepared

  16. Sodium conducting polymer electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Skaarup, S.; West, K. (eds.)

    1989-04-01

    This section deals with the aspects of ionic conduction in general as well as specific experimental results obtained for sodium systems. The conductivity as a function of temperature and oxygen/metal ratio are given for the systems NaI, NaCF/sub 3/SO/sub 3/ and NaClO/sub 4/ plus polyethylene oxide. Attempts have been made to produce mixed phase solid electrolytes analogous to the lithium systems that have worked well. These consist of mixtures of polymer and a solid electrolyte. The addition of both nasicon and sodium beta alumina unexpectedly decreases the ionic conductivity in contrast to the lithium systems. Addition of the nonconducting silica AEROSIL in order to increase the internal surface area has the effect of retarding the phase transition at 60 deg. C, but does not enhance the conductivity. (author) 23 refs.

  17. Modeling removal of accumulated potassium from T-tubules by inward rectifier potassium channels

    NARCIS (Netherlands)

    Wallinga, W.; Vliek, M.; Wienk, E.D.; Alberink, M.J.; Ypey, D.L.; Ypey, D.L.

    1996-01-01

    The membrane models of Cannon et al. (1993) and Alberink et al. (1995) for mammalian skeletal muscle fibers are based upon Hodgkin-Huxley descriptions of sodium, potassium delayed rectifier and leak conductances and the capacitive current taking into account fast inactivation of sodium channels. Now

  18. Heteromeric Kv7.2/7.3 channels differentially regulate action potential initiation and conduction in neocortical myelinated axons

    NARCIS (Netherlands)

    Battefeld, A.; Tran, B.T.; Gavrilis, J.; Cooper, E.C.; Kole, Maarten|info:eu-repo/dai/nl/256257574

    2014-01-01

    Rapid energy-efficient signaling along vertebrate axons is achieved through intricate subcellular arrangements of voltage-gated ion channels and myelination. One recently appreciated example is the tight colocalization of Kv7 potassium channels and voltage-gated sodium (Nav ) channels in the axonal

  19. Heteromeric Kv7.2/7.3 channels differentially regulate action potential initiation and conduction in neocortical myelinated axons

    NARCIS (Netherlands)

    Battefeld, A.; Tran, Baouyen T; Gavrilis, Jason; Cooper, Edward C; Kole, Maarten H P

    2014-01-01

    Rapid energy-efficient signaling along vertebrate axons is achieved through intricate subcellular arrangements of voltage-gated ion channels and myelination. One recently appreciated example is the tight colocalization of K(v)7 potassium channels and voltage-gated sodium (Na(v)) channels in the

  20. Enolasa específica de neurona en dos recién nacidos con depresión ligera al nacer Neuron- specific Enolase in two newborns presenting with moderate depression at birth

    Directory of Open Access Journals (Sweden)

    Raisa Bu-Coifiu Fanego

    2009-03-01

    Full Text Available INTRODUCCIÓN. La enolasa específica de neurona es una isoenzima que se vierte al torrente sanguíneo después de un episodio de daño neuronal. En los procesos de hipoxia neonatal estos valores enzimáticos en suero suelen estar alterados. El objetivo del presente artículo fue estudiar la enolasa específica de neurona en suero de 2 recién nacidos con Apgar bajo y determinar si, en el seguimiento durante un año, dichos pacientes presentaban trastornos del desarrollo psicomotor. MÉTODOS. Se tomaron muestras de suero al momento del nacimiento y a las 72 h siguientes. Se determinaron los niveles de enolasa específica de neurona por un método inmunoenzimático de tipo ELISA. Cada muestra fue evaluada por el método de reacción en cadena de la polimerasa para citomegalovirus, en el Instituto de Inmunología de Wuersburg (Alemania. También se cuantificaron anticuerpos contra citomegalovirus de clase IgM e IgG, en el Laboratorio de Neuroquímica de la Universidad Georg August de Goettingen (Alemania. Se recogieron los datos clínicos de interés de cada recién nacido y al año se citaron a estos pacientes y se les realizó un examen físico para evaluar su neurodesarrollo. RESULTADOS. Las cifras de enolasa estuvieron incrementadas tanto al nacimiento como a las 72 h, con anticuerpos anticitomegalovirus de clase IgG que fueron transferidos de la madre a través de la placenta. No se encontró presencia de este virus en el momento del nacimiento. En el examen físico y neurológico realizado al año se constató que los niños evolucionaban satisfactoriamente hasta esa fecha. CONCLUSIONES. Se recomienda extender el estudio hasta los 3 años de vida y aumentar el número de pacientes estudiados, con énfasis en aquellos casos cuyo Apgar es menor de 5 a los 5 min del nacimiento.INTRODUCTION: Neuron-specific Enolase of is an isoenzyme present in blood stream after a neuronal damage episode. In processes of neonatal hypoxia, these enzymatic values

  1. A study on sodium-concrete reaction

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Jae Heum; Min, Byong Hun [Suwon University, Suwon (Korea, Republic of)

    1997-07-01

    A small sodium-concrete reaction facility was designed, manufactured and installed. this facility has been operated under inert gas(N{sub 2}) with different experimental variables such as sodium