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voltage-gated Na channel

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https://www.readbyqxmd.com/read/28424991/expression-and-role-of-voltage-gated-sodium-channels-in-human-dorsal-root-ganglion-neurons-with-special-focus-on-nav1-7-species-differences-and-regulation-by-paclitaxel
#1
Wonseok Chang, Temugin Berta, Yong Ho Kim, Sanghoon Lee, Seok-Yong Lee, Ru-Rong Ji
Voltage-gated sodium channels (Navs) play an important role in human pain sensation. However, the expression and role of Nav subtypes in native human sensory neurons are unclear. To address this issue, we obtained human dorsal root ganglion (hDRG) tissues from healthy donors. PCR analysis of seven DRG-expressed Nav subtypes revealed that the hDRG has higher expression of Nav1.7 (~50% of total Nav expression) and lower expression of Nav1.8 (~12%), whereas the mouse DRG has higher expression of Nav1.8 (~45%) and lower expression of Nav1...
April 19, 2017: Neuroscience Bulletin
https://www.readbyqxmd.com/read/28423317/loss-of-nav%C3%AE-4-mediated-regulation-of-sodium-currents-in-adult-purkinje-neurons-disrupts-firing-and-impairs-motor-coordination-and-balance
#2
Joseph L Ransdell, Edward Dranoff, Brandon Lau, Wan-Lin Lo, David L Donermeyer, Paul M Allen, Jeanne M Nerbonne
The resurgent component of voltage-gated Na(+) (Nav) currents, INaR, has been suggested to provide the depolarizing drive for high-frequency firing and to be generated by voltage-dependent Nav channel block (at depolarized potentials) and unblock (at hyperpolarized potentials) by the accessory Navβ4 subunit. To test these hypotheses, we examined the effects of the targeted deletion of Scn4b (Navβ4) on INaR and on repetitive firing in cerebellar Purkinje neurons. We show here that Scn4b(-/-) animals have deficits in motor coordination and balance and that firing rates in Scn4b(-/-) Purkinje neurons are markedly attenuated...
April 18, 2017: Cell Reports
https://www.readbyqxmd.com/read/28423185/functional-identification-of-activity-regulated-high-affinity-glutamine-transport-in-hippocampal-neurons-inhibited-by-riluzole
#3
Jeffrey D Erickson
Glutamine (Gln) is considered the preferred precursor for the neurotransmitter pool of glutamate (Glu), the major excitatory transmitter in the mammalian CNS. Here, an activity-regulated, high-affinity Gln transport system is described in developing and mature neuron-enriched hippocampal cultures that is potently inhibited by riluzole (IC50 1.3 +/- 0.5μM), an anti-glutamatergic drug, and is blocked by low concentrations of 2-(methylamino)isobutyrate (MeAIB), a system A transport inhibitor. K(+) -stimulated MeAIB transport displays an affinity (Km ) for MeAIB of 37 +/- 1...
April 19, 2017: Journal of Neurochemistry
https://www.readbyqxmd.com/read/28416648/isoflurane-modulates-activation-and-inactivation-gating-of-the-prokaryotic-na-channel-nachbac
#4
Rheanna M Sand, Kevin J Gingrich, Tamar Macharadze, Karl F Herold, Hugh C Hemmings
Voltage-gated Na(+) channels (Nav) have emerged as important presynaptic targets for volatile anesthetic (VA) effects on synaptic transmission. However, the detailed biophysical mechanisms by which VAs modulate Nav function remain unclear. VAs alter macroscopic activation and inactivation of the prokaryotic Na(+) channel, NaChBac, which provides a useful structural and functional model of mammalian Nav Here, we study the effects of the common general anesthetic isoflurane on NaChBac function by analyzing macroscopic Na(+) currents (INa) in wild-type (WT) channels and mutants with impaired (G229A) or enhanced (G219A) inactivation...
April 17, 2017: Journal of General Physiology
https://www.readbyqxmd.com/read/28408211/cardiac-voltage-gated-ion-channels-in-safety-pharmacology-review-of-the-landscape-leading-to-the-cipa-initiative
#5
REVIEW
Hai Huang, Michael K Pugsley, Bernard Fermini, Michael J Curtis, John Koerner, Michael Accardi, Simon Authier
Voltage gated ion channels are central in defining the fundamental properties of the ventricular cardiac action potential (AP), and are also involved in the development of drug-induced arrhythmias. Many drugs can inhibit cardiac ion currents, including the Na(+) current (INa), L-type Ca(2+) current (Ica-L), and K(+) currents (Ito, IK1, IKs, and IKr), and thereby affect AP properties in a manner that can trigger or sustain cardiac arrhythmias. Since publication of ICH E14 and S7B over a decade ago, there has been a focus on drug effects on QT prolongation clinically, and on the rapidly activating delayed rectifier current (IKr), nonclinically, for evaluation of proarrhythmic risk...
April 10, 2017: Journal of Pharmacological and Toxicological Methods
https://www.readbyqxmd.com/read/28406893/the-chemical-basis-for-electrical-signaling
#6
REVIEW
William A Catterall, Goragot Wisedchaisri, Ning Zheng
Electrical signals generated by minute currents of ions moving across cell membranes are central to all rapid processes in biology. Initiation and propagation of electrical signals requires voltage-gated sodium (NaV) and calcium (CaV) channels. These channels contain a tetramer of membrane-bound subunits or domains comprising a voltage sensor and a pore module. Voltage-dependent activation occurs as membrane depolarization drives outward movements of positive gating changes in the voltage sensor via a sliding-helix mechanism, which leads to a conformational change in the pore module that opens its intracellular activation gate...
April 13, 2017: Nature Chemical Biology
https://www.readbyqxmd.com/read/28402882/gating-charge-calculations-by-computational-electrophysiology-simulations
#7
Jan-Philipp Machtens, Rodolfo Briones, Claudia Alleva, Bert L de Groot, Christoph Fahlke
Electrical cell signaling requires adjustment of ion channel, receptor, or transporter function in response to changes in membrane potential. For the majority of such membrane proteins, the molecular details of voltage sensing remain insufficiently understood. Here, we present a molecular dynamics simulation-based method to determine the underlying charge movement across the membrane-the gating charge-by measuring electrical capacitor properties of membrane-embedded proteins. We illustrate the approach by calculating the charge transfer upon membrane insertion of the HIV gp41 fusion peptide, and validate the method on two prototypical voltage-dependent proteins, the Kv1...
April 11, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28394849/inhibition-of-voltage-gated-na-channels-by-bupivacaine-is-enhanced-by-the-adjuvants-buprenorphine-ketamine-and-clonidine
#8
Carsten Stoetzer, Christine Martell, Jeanne de la Roche, Andreas Leffler
BACKGROUND AND OBJECTIVES: Regional anesthesia includes application of local anesthetics (LAs) into the vicinity of peripheral nerves. Prolongation or improvement of nerve blocks with LAs can be accomplished by coapplication with adjuvants, including buprenorphine, ketamine, and clonidine. While the mechanisms mediating prolonged or improved LA-induced effects by adjuvants are poorly understood, we hypothesized that they are likely to increase LA-induced block of voltage-gated Na channels...
April 7, 2017: Regional Anesthesia and Pain Medicine
https://www.readbyqxmd.com/read/28385801/mechanisms-controlling-glucose-induced-glp-1-secretion-in-human-small-intestine
#9
Emily W Sun, Dayan de Fontgalland, Philippa Rabbitt, Paul Hollington, Luigi Sposato, Steven L Due, David A Wattchow, Christopher K Rayner, Adam M Deane, Richard L Young, Damien J Keating
Intestinal glucose stimulates secretion of the incretin hormone glucagon-like peptide 1 (GLP-1). The mechanisms underlying this pathway have not been fully investigated in humans. In this study, we showed that a 30 minute intraduodenal glucose infusion activated half of all duodenal L cells in humans. This infusion was sufficient to increase plasma GLP-1. With an ex vivo model using human gut tissue specimens, we showed a dose-responsive GLP-1 secretion in ileum at 200mM glucose or above. In ex vivo tissue from duodenum and ileum, but not colon, 300mM glucose potently stimulated GLP-1 release...
April 6, 2017: Diabetes
https://www.readbyqxmd.com/read/28378799/non-photonic-sensing-of-membrane-delimited-reactive-species-with-a-na-channel-protein-containing-selenocysteine
#10
Navin K Ojha, Enrico Leipold, Roland Schönherr, Toshinori Hoshi, Stefan H Heinemann
Photonic experiments are of key importance in life sciences but light-induced side effects are serious confounding factors. Here we introduce roNaV2, an engineered voltage-gated Na(+) channel harboring a selenocysteine in its inactivation motif, as a non-photonic, sensitive, gateable, and reversible sensor for membrane-delimited reactive species. roNaV2 allows for the assessment of chemical modification induced in fluorescence microscopy settings with high sensitivity and time resolution and it demonstrates the usefulness of ion channels as highly sensitive reporters of membrane processes...
April 5, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28370141/increased-transient-na-conductance-and-action-potential-output-in-layer-2-3-prefrontal-cortex-neurons-of-the-fmr1-y-mouse
#11
Brandy N Routh, Rahul K Rathour, Michael E Baumgardner, Brian E Kalmbach, Daniel Johnston, Darrin H Brager
Fragile X syndrome is the most common form of inherited mental impairment and autism. The prefrontal cortex is responsible for higher order cognitive processing, and prefrontal dysfunction is believed to underlie many of the cognitive and behaviour phenotypes associated with Fragile X syndrome. We recently demonstrated that somatic and dendritic excitability of layer 5 pyramidal neurons in the prefrontal cortex of the fmr1-/y mouse is significantly altered due to changes in several voltage-gated ion channels...
March 31, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28361268/resveratrol-attenuates-a%C3%AE-induced-early-hippocampal-neuron-excitability-impairment-via-recovery-of-function-of-potassium-channels
#12
Hongqiang Yin, Hui Wang, Hui Zhang, Na Gao, Tao Zhang, Zhuo Yang
Alzheimer's disease (AD) is an age-related neurodegenerative disease. Amyloid-β (Aβ) is not only the morphological hallmark but also the initiator of the pathology process of AD. As a natural compound found in grapes, resveratrol shows a protective effect on the pathophysiology of AD, but the underlying mechanism is not very clear. This study was to investigate whether resveratrol could attenuate Aβ-induced early impairment in hippocampal neuron excitability and the underlying mechanism. The excitability and voltage-gated potassium currents were examined in rat hippocampal CA1 pyramidal neurons by using whole-cell patch-clamp technique...
March 30, 2017: Neurotoxicity Research
https://www.readbyqxmd.com/read/28359334/cytokine-cascades-induced-by-mechanical-trauma-injury-alter-voltage-gated-sodium-channel-activity-in-intact-cortical-neurons
#13
Weiqiang Chen, Jiangtao Sheng, Jingfang Guo, Guoyi Peng, Jinfang Hong, Bingbing Li, Xiaoxuan Chen, Kangsheng Li, Shousen Wang
BACKGROUND: Traumatic brain injury (TBI) triggers both immediate (primary) and long-term (secondary) tissue damages. Secondary damages can last from hours to days or even a lifetime. Secondary damages implicate several mechanisms, including influence of inflammatory mediators, mainly cytokines, on excitability of ion channels. However, studies should further explore the effects of inflammatory cytokines on voltage-gated sodium channels (VGSCs) and excitability in distal intact neurons...
March 31, 2017: Journal of Neuroinflammation
https://www.readbyqxmd.com/read/28348242/structures-of-closed-and-open-states-of-a-voltage-gated-sodium-channel
#14
Michael J Lenaeus, Tamer M Gamal El-Din, Christopher Ing, Karthik Ramanadane, Régis Pomès, Ning Zheng, William A Catterall
Bacterial voltage-gated sodium channels (BacNavs) serve as models of their vertebrate counterparts. BacNavs contain conserved voltage-sensing and pore-forming domains, but they are homotetramers of four identical subunits, rather than pseudotetramers of four homologous domains. Here, we present structures of two NaVAb mutants that capture tightly closed and open states at a resolution of 2.8-3.2 Å. Introduction of two humanizing mutations in the S6 segment (NaVAb/FY: T206F and V213Y) generates a persistently closed form of the activation gate in which the intracellular ends of the four S6 segments are drawn tightly together to block ion permeation completely...
March 27, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28330839/evolutionary-insights-into-t-type-ca-2-channel-structure-function-and-ion-selectivity-from-the-trichoplax-adhaerens-homologue
#15
Carolyn L Smith, Salsabil Abdallah, Yuen Yan Wong, Phuong Le, Alicia N Harracksingh, Liana Artinian, Arianna N Tamvacakis, Vincent Rehder, Thomas S Reese, Adriano Senatore
Four-domain voltage-gated Ca(2+) (Cav) channels play fundamental roles in the nervous system, but little is known about when or how their unique properties and cellular roles evolved. Of the three types of metazoan Cav channels, Cav1 (L-type), Cav2 (P/Q-, N- and R-type) and Cav3 (T-type), Cav3 channels are optimized for regulating cellular excitability because of their fast kinetics and low activation voltages. These same properties permit Cav3 channels to drive low-threshold exocytosis in select neurons and neurosecretory cells...
April 3, 2017: Journal of General Physiology
https://www.readbyqxmd.com/read/28328149/comparative-genomic-analyses-of-transport-proteins-encoded-within-the-red-algae-chondrus-crispus-galdieria-sulphuraria-and-cyanidioschyzon-merolae
#16
Justin Lee, Shounak Ghosh, Milton H Saier
Galdieria sulphuraria and Cyanidioschyzon merolae are thermo-acidophilic unicellular red algal cousins capable of living in volcanic environments, although the former can additionally thrive in the presence of toxic heavy metals. Bioinformatic analyses of transport systems were carried out on their genomes, as well as that of the mesophilic multicellular red alga Chondrus crispus (Irish moss). We identified transport proteins related to the metabolic capabilities, physiological properties, and environmental adaptations of these organisms...
March 22, 2017: Journal of Phycology
https://www.readbyqxmd.com/read/28320963/conformational-dynamics-and-role-of-the-acidic-pocket-in-asic-ph-dependent-gating
#17
Sabrina Vullo, Gaetano Bonifacio, Sophie Roy, Niklaus Johner, Simon Bernèche, Stephan Kellenberger
Acid-sensing ion channels (ASICs) are proton-activated Na(+) channels expressed in the nervous system, where they are involved in learning, fear behaviors, neurodegeneration, and pain sensation. In this work, we study the role in pH sensing of two regions of the ectodomain enriched in acidic residues: the acidic pocket, which faces the outside of the protein and is the binding site of several animal toxins, and the palm, a central channel domain. Using voltage clamp fluorometry, we find that the acidic pocket undergoes conformational changes during both activation and desensitization...
April 4, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28293175/two-photon-na-imaging-reports-somatically-evoked-action-potentials-in-rat-olfactory-bulb-mitral-and-granule-cell-neurites
#18
Tiffany Ona-Jodar, Niklas J Gerkau, S Sara Aghvami, Christine R Rose, Veronica Egger
Dendrodendritic synaptic interactions are a hallmark of neuronal processing in the vertebrate olfactory bulb. Many classes of olfactory bulb neurons including the principal mitral cells (MCs) and the axonless granule cells (GCs) dispose of highly efficient propagation of action potentials (AP) within their dendrites, from where they can release transmitter onto each other. So far, backpropagation in GC dendrites has been investigated indirectly via Ca(2+) imaging. Here, we used two-photon Na(+) imaging to directly report opening of voltage-gated sodium channels due to AP propagation in both cell types...
2017: Frontiers in Cellular Neuroscience
https://www.readbyqxmd.com/read/28265756/sodium-channel-biophysics-late-sodium-current-and-genetic-arrhythmic-syndromes
#19
REVIEW
Karan R Chadda, Kamalan Jeevaratnam, Ming Lei, Christopher L-H Huang
Arrhythmias arise from breakdown of orderly action potential (AP) activation, propagation and recovery driven by interactive opening and closing of successive voltage-gated ion channels, in which one or more Na(+) current components play critical parts. Early peak, Na(+) currents (I Na) reflecting channel activation drive the AP upstroke central to cellular activation and its propagation. Sustained late Na(+) currents (I Na-L) include contributions from a component with a delayed inactivation timecourse influencing AP duration (APD) and refractoriness, potentially causing pro-arrhythmic phenotypes...
March 6, 2017: Pflügers Archiv: European Journal of Physiology
https://www.readbyqxmd.com/read/28257815/gadolinium-released-by-the-linear-gadolinium-based-contrast-agent-gd-dtpa-decreases-the-activity-of-human-epithelial-na-channels-enacs
#20
Fenja Knoepp, Joerg Bettmer, Martin Fronius
BACKGROUND: Gadolinium-based-contrast-agents (GBCAs) are used for magnetic-resonance-imaging and associated with renal and cardiovascular adverse reactions caused by released Gd(3+) ions. Gd(3+) is also a modulator of mechano-gated ion channels, including the epithelial Na(+) channel (ENaC) that is expressed in kidney epithelium and the vasculature. ENaC is important for salt-/water homeostasis and blood pressure regulation and a likely target of released Gd(3+) from GBCAs causing the above-mentioned adverse reactions...
May 2017: Biochimica et Biophysica Acta
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