Tetrodotoxin-sensitive α-subunits of voltage-gated sodium channels are relevant for inhibition of cardiac sodium currents by local anesthetics

2016 ◽  
Vol 389 (6) ◽  
pp. 625-636 ◽  
Author(s):  
C. Stoetzer ◽  
T. Doll ◽  
T. Stueber ◽  
C. Herzog ◽  
F. Echtermeyer ◽  
...  
Keyword(s):  
Sodium Channels ◽  
Local Anesthetics ◽  
Sodium Currents ◽  
Voltage Gated ◽  
Voltage Gated Sodium Channels ◽  
Α Subunits

scholarly journals Neurosteroids Allopregnanolone Sulfate and Pregnanolone Sulfate Have Diverse Effect on the α Subunit of the Neuronal Voltage-gated Sodium Channels Nav1.2, Nav1.6, Nav1.7, and Nav1.8 Expressed in Xenopus Oocytes

2014 ◽  
Vol 121 (3) ◽  
pp. 620-631 ◽  
Author(s):  
Takafumi Horishita ◽  
Nobuyuki Yanagihara ◽  
Susumu Ueno ◽  
Yuka Sudo ◽  
Yasuhito Uezono ◽  
...  
Keyword(s):  
Sodium Channels ◽  
Xenopus Oocytes ◽  
Sodium Current ◽  
Dependent Manner ◽  
Sodium Currents ◽  
Concentration Dependent Manner ◽  
Α Subunit ◽  
Voltage Gated ◽  
Voltage Gated Sodium Channels ◽  
Α Subunits

Abstract Background: The neurosteroids allopregnanolone and pregnanolone are potent positive modulators of γ-aminobutyric acid type A receptors. Antinociceptive effects of allopregnanolone have attracted much attention because recent reports have indicated the potential of allopregnanolone as a therapeutic agent for refractory pain. However, the analgesic mechanisms of allopregnanolone are still unclear. Voltage-gated sodium channels (Nav) are thought to play important roles in inflammatory and neuropathic pain, but there have been few investigations on the effects of allopregnanolone on sodium channels. Methods: Using voltage-clamp techniques, the effects of allopregnanolone sulfate (APAS) and pregnanolone sulfate (PAS) on sodium current were examined in Xenopus oocytes expressing Nav1.2, Nav1.6, Nav1.7, and Nav1.8 α subunits. Results: APAS suppressed sodium currents of Nav1.2, Nav1.6, and Nav1.7 at a holding potential causing half-maximal current in a concentration-dependent manner, whereas it markedly enhanced sodium current of Nav1.8 at a holding potential causing maximal current. Half-maximal inhibitory concentration values for Nav1.2, Nav1.6, and Nav1.7 were 12 ± 4 (n = 6), 41 ± 2 (n = 7), and 131 ± 15 (n = 5) μmol/l (mean ± SEM), respectively. The effects of PAS were lower than those of APAS. From gating analysis, two compounds increased inactivation of all α subunits, while they showed different actions on activation of each α subunit. Moreover, two compounds showed a use-dependent block on Nav1.2, Nav1.6, and Nav1.7. Conclusion: APAS and PAS have diverse effects on sodium currents in oocytes expressing four α subunits. APAS inhibited the sodium currents of Nav1.2 most strongly.

Spectral Investigations, Molecular Interactions and Electrochemical Studies of (2R)-(-)2-(2, 6-dimethylphenylaminocarbonyl)-1-methyl Piperidinium Chloride

2020 ◽  
Vol 15 (4) ◽  
pp. 358-368
Author(s):  
J. Deva Anban ◽  
J. Sharmi Kumar ◽  
C. James ◽  
Sayantan Pradhan
Keyword(s):  
Sodium Channels ◽  
Local Anesthetics ◽  
Natural Bond Orbital ◽  
Nbo Analysis ◽  
Basis Set ◽  
Voltage Gated ◽  
Peripheral Neurons ◽  
Voltage Gated Sodium Channels ◽  
Title Molecule ◽  
Inner Pore

Background: Local anesthetics are widely used to decrease sensitivity to pain in specific regions of the body while performing medical tasks. Many studies have probed the mechanism of action of local anesthetics but still many questions remain. (2R - (-) 2 - (2, 6-dimethylphenylaminocarbonyl) - 1 – methyl piperidinium chloride (DAMP), is an extensively used amide-type local anesthetic. Objective: This study aims at revealing the various electrophysical and chemical properties of the title compound. This study will be useful for future research by pharmacologists. Method: Density Functional Theory (DFT) computations were executed using Gaussian’09 program package and were optimized with the B3LYP /6-311+G (d, p) basis set. Natural bond orbital (NBO) analysis was carried out with version 3.1. Normal Coordinate Analysis (NCA) was used to systematically calculate the harmonic vibrational wavenumbers. Molecular docking simulations were carried out to understand the pharmacokinetic behavior of the drug. Results: The presence of strong N-H…Cl intra molecular hydrogen bonding was evidently revealed from the FT-IR spectrum due to the shifting of NH stretching wavenumber. Stability of the molecule arising from hyper conjugative interactions exhibits the bioactivity of the molecule by natural bond orbital analysis. The title molecule binds to the inner pore and blocks voltage - gated sodium channels in peripheral neurons. Conclusion: A detailed molecular picture of DAMP and its interactions were obtained by modeling analysis, IR, Raman, and UV-Vis spectroscopy. The geometrical parameters agree well with the XRD data. NBO analysis indicates the bioactivity of the molecule. The HOMO-LUMO energy gap indicates the possibility of intramolecular charge transfer of the molecule. From the ligand docking studies it is concluded that the title molecule binds to the inner pore and blocks voltage - gated sodium channels in peripheral neurons.

scholarly journals Neuropathic Pain Develops Normally in Mice Lacking both Nav1.7 and Nav1.8

2005 ◽  
Vol 1 ◽  
pp. 1744-8069-1-24 ◽  
Author(s):  
Mohammed A Nassar ◽  
Alessandra Levato ◽  
L Caroline Stirling ◽  
John N Wood
Keyword(s):  
Neuropathic Pain ◽  
Sodium Channels ◽  
Sensory Neurons ◽  
Inflammatory Pain ◽  
Pain Thresholds ◽  
Voltage Gated ◽  
Voltage Gated Sodium Channels ◽  
Pain Symptoms ◽  
Α Subunits

Two voltage gated sodium channel α-subunits, Nav1.7 and Nav1.8, are expressed at high levels in nociceptor terminals and have been implicated in the development of inflammatory pain. Mis-expression of voltage-gated sodium channels by damaged sensory neurons has also been implicated in the development of neuropathic pain, but the role of Nav1.7 and Nav1.8 is uncertain. Here we show that deleting Nav1.7 has no effect on the development of neuropathic pain. Double knockouts of both Nav1.7 and Nav1.8 also develop normal levels of neuropathic pain, despite a lack of inflammatory pain symptoms and altered mechanical and thermal acute pain thresholds. These studies demonstrate that, in contrast to the highly significant role for Nav1.7 in determining inflammatory pain thresholds, the development of neuropathic pain does not require the presence of either Nav1.7 or Nav1.8 alone or in combination.

Molecular determinants of prokaryotic voltage-gated sodium channels for recognition of local anesthetics

FEBS Journal ◽  
2016 ◽  
Vol 283 (15) ◽  
pp. 2881-2895 ◽  
Author(s):  
Takushi Shimomura ◽  
Katsumasa Irie ◽  
Yoshinori Fujiyoshi
Keyword(s):  
Sodium Channels ◽  
Local Anesthetics ◽  
Voltage Gated ◽  
Voltage Gated Sodium Channels ◽  
Molecular Determinants

scholarly journals α- And β-subunit composition of voltage-gated sodium channels investigated with μ-conotoxins and the recently discovered μO§-conotoxin GVIIJ

2015 ◽  
Vol 113 (7) ◽  
pp. 2289-2301 ◽  
Author(s):  
Michael J. Wilson ◽  
Min-Min Zhang ◽  
Joanna Gajewiak ◽  
Layla Azam ◽  
Jean E. Rivier ◽  
...  
Keyword(s):  
Sciatic Nerve ◽  
Sodium Channels ◽  
Action Potentials ◽  
Xenopus Laevis Oocytes ◽  
Sodium Currents ◽  
Voltage Gated ◽  
Voltage Gated Sodium Channels ◽  
Compound Action Potentials ◽  
Sciatic Nerves ◽  
Synthetic Derivatives

We investigated the identities of the isoforms of the α (NaV1)- and β (NaVβ)-subunits of voltage-gated sodium channels, including those responsible for action potentials in rodent sciatic nerves. To examine α-subunits, we used seven μ-conotoxins, which target site 1 of the channel. With the use of exogenously expressed channels, we show that two of the μ-conotoxins, μ-BuIIIB and μ-SxIIIA, are 50-fold more potent in blocking NaV1.6 from mouse than that from rat. Furthermore, we observed that μ-BuIIIB and μ-SxIIIA are potent blockers of large, myelinated A-fiber compound action potentials (A-CAPs) [but not small, unmyelinated C-fiber CAPs (C-CAPs)] in the sciatic nerve of the mouse (unlike A-CAPs of the rat, previously shown to be insensitive to these toxins). To investigate β-subunits, we used two synthetic derivatives of the recently discovered μO§-conotoxin GVIIJ that define site 8 of the channel, as previously characterized with cloned rat NaV1- and NaVβ-subunits expressed in Xenopus laevis oocytes, where it was shown that μO§-GVIIJ is a potent inhibitor of several NaV1-isoforms and that coexpression of NaVβ2 or -β4 (but not NaVβ1 or -β3) totally protects against block by μO§-GVIIJ. We report here the effects of μO§-GVIIJ on 1) sodium currents of mouse NaV1.6 coexpressed with various combinations of NaVβ-subunits in oocytes; 2) A- and C-CAPs of mouse and rat sciatic nerves; and 3) sodium currents of small and large neurons dissociated from rat dorsal root ganglia. Our overall results lead us to conclude that action potentials in A-fibers of the rodent sciatic nerve are mediated primarily by NaV1.6 associated with NaVβ2 or NaVβ4.

Cloning of a putative voltage-gated sodium channel from the turbellarian flatworm Bdelloura candida

Parasitology ◽  
1997 ◽  
Vol 115 (3) ◽  
pp. 289-296 ◽  
Author(s):  
M. C. JEZIORSKI ◽  
R. M. GREENBERG ◽  
P. A. V. ANDERSON
Keyword(s):  
Sodium Channels ◽  
Northern Blot Analysis ◽  
Amino Acid Identity ◽  
Structure Characteristic ◽  
Sodium Currents ◽  
Voltage Gated ◽  
Transmembrane Segments ◽  
Voltage Gated Sodium Channels ◽  
Multidomain Structure ◽  
Insight Into

The neuromuscular sodium currents of early invertebrates such as platyhelminths display distinctive kinetic and pharmacological properties. We have cloned a cDNA from the horseshoe crab flatworm Bdelloura candida that encodes a protein homologous to the primary subunit of voltage-gated sodium channels. The B. candida protein, named BdNa1, exhibits amino acid identity of 40–47% to sodium channels of vertebrates and higher invertebrates. BdNa1 has the multidomain structure characteristic of sodium channels, and is most highly conserved in the hydrophobic transmembrane segments and the regions that form the pore of the channel. Northern blot analysis confirms the presence of a 5·4 kb BdNa1 transcript in B. candida tissue. The information provided by analysis of the BdNa1 sequence offers insight into the physiology of platyhelminth sodium currents.

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