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Sodium channel

Bernd R Gardill, Ricardo E Rivera-Acevedo, Ching-Chieh Tung, Mark Okon, Lawrence P McIntosh, Filip Van Petegem
Voltage-gated sodium channels (NaV ) are responsible for the rapid depolarization of many excitable cells. They readily inactivate, a process where currents diminish after milliseconds of channel opening. They are also targets for a multitude of disease-causing mutations, many of which have been shown to affect inactivation. A cluster of disease mutations, linked to Long-QT and Brugada syndromes, is located in a C-terminal EF-hand like domain of NaV 1.5, the predominant cardiac sodium channel isoform. Previous studies have suggested interactions with the III-IV linker, a cytosolic element directly involved in inactivation...
March 14, 2018: Scientific Reports
Ben Warren, Tom Matheson
Insect auditory receivers provide an excellent comparative resource to understand general principles of auditory transduction, but analysis of the electrophysiological properties of the auditory neurons has been hampered by their tiny size and inaccessibility. Here we pioneer patch-clamp recordings from the auditory neurons of Müller-s Organ of the desert locust Schistocerca gregaria to characterise dendritic spikes, axonal spikes and the transduction current. We demonstrate that dendritic spikes, elicited by sound stimuli, trigger axonal spikes, and that both types are sodium- and voltage-dependent and blocked by TTX...
March 14, 2018: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Jonathan V Martin, David M Liberati, Lawrence N Diebel
BACKGROUND: Hypernatremia is a common problem affecting critically ill patients, whether due to underlying pathology or the subsequent result of hypertonic fluid resuscitation. Numerous studies have been published suggesting that hypernatremia may adversely affect the vascular endothelial glycocalyx. Our study aimed to evaluate if high sodium concentration would impair the endothelial and glycocalyx barrier function and if stress conditions that simulate the shock microenvironment would exacerbate any observed adverse effects of hypernatremia...
March 12, 2018: Journal of Trauma and Acute Care Surgery
M Marin-Gracia, D Cantero-Lozano, E Garces-Anton, A Lopez-Bravo, A Garrido-Fernandez, M P Navarro-Perez, S Santos-Lasaosa, M Garces-Redondo
INTRODUCTION: Lacosamide is an antiepileptic drug whose exact mechanism of action remains unknown. It acts by increasing the slow inactivation of the voltage-dependent sodium channels of the cell membranes. It is indicated in the treatment of focal seizures with or without secondary generalisation and is occasionally used as adjunct treatment in neuropathic pain. Although the most frequent side effects are mild (dizziness, diplopia, blurred vision, headache, tremor, etc.), others such as supraventricular tachyarrhythmias, changes in repolarisation, atrioventricular blocks and even cardiac arrest or sudden death have been reported...
March 16, 2018: Revista de Neurologia
Thomas Berk, Stephen D Silberstein
BACKGROUND: Lidocaine, an amide anesthetic, has been used in the treatment of a wide variety of pain disorders for over 75 years. In addition to pain control, lidocaine is an anti-arrhythmic agent and has anti-inflammatory properties. Lidocaine's unique properties, including nonlinear pharmacokinetics, have limited its modern-day use. OBJECTIVE: The purpose of this review is to offer a better understanding of the properties of this unique treatment, which we hope will allow more practitioners to offer this to their patients...
March 14, 2018: Headache
István Z Bátai, Ádám Horváth, Erika Pintér, Zsuzsanna Helyes, Gábor Pozsgai
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)...
2018: Frontiers in Endocrinology
Martina Tetti, Silvia Monticone, Jacopo Burrello, Patrizia Matarazzo, Franco Veglio, Barbara Pasini, Xavier Jeunemaitre, Paolo Mulatero
Liddle syndrome is an inherited form of low-renin hypertension, transmitted with an autosomal dominant pattern. The molecular basis of Liddle syndrome resides in germline mutations of the SCNN1A , SCNN1B and SCNN1G genes, encoding the α, β, and γ-subunits of the epithelial Na⁺ channel (ENaC), respectively. To date, 31 different causative mutations have been reported in 72 families from four continents. The majority of the substitutions cause an increased expression of the channel at the distal nephron apical membrane, with subsequent enhanced renal sodium reabsorption...
March 11, 2018: International Journal of Molecular Sciences
Michael L Yuan, Ian J Wang
Spatial heterogeneity in the strength or agents of selection can lead to geographic variation in ecologically important phenotypes. Many dendrobatid frogs sequester alkaloid toxins from their diets and often exhibit fixed mutations at NaV1.4, a voltage-gated sodium ion channel associated with alkaloid toxin resistance. Yet previous studies have noted an absence of resistance mutations in individuals from several species known to sequester alkaloid toxins, suggesting possible intraspecific variation for alkaloid resistance in these species...
2018: PloS One
Nirupa D Jayaraj, Bula J Bhattacharyya, Abdelhak A Belmadani, Dongjun Ren, Craig A Rathwell, Sandra Hackelberg, Brittany E Hopkins, Herschel R Gupta, Richard J Miller, Daniela M Menichella
Painful diabetic neuropathy (PDN) is an intractable complication of diabetes that affects 25% of patients. PDN is characterized by neuropathic pain and small-fiber degeneration, accompanied by dorsal root ganglion (DRG) nociceptor hyperexcitability and loss of their axons within the skin. The molecular mechanisms underlying DRG nociceptor hyperexcitability and small-fiber degeneration in PDN are unknown. We hypothesize that chemokine CXCL12/CXCR4 signaling is central to this mechanism, as we have shown that CXCL12/CXCR4 signaling is necessary for the development of mechanical allodynia, a pain hypersensitivity behavior common in PDN...
March 13, 2018: Journal of Clinical Investigation
Sha Yan, Pengfei Huang, Ying Wang, Xiongzhi Zeng, Yiya Zhang
Spider venoms are known to contain various toxins that are used as an effective means to capture their prey or to defend themselves against predators. An investigation of the properties of Ornithoctonus huwena (O.huwena) crude venom found that the venom can block neuromuscular transmission of isolated mouse phrenic nerve-diaphragm and sciatic nerve-sartorius preparations. However, little is known about its electrophysiological effects on cardiac myocytes. In this study, electrophysiological activities of ventricular myocytes were detected by 100 μg/mL venom of O...
March 13, 2018: Channels
Jian Payandeh, David H Hackos
The voltage-gated sodium (Nav) channel Nav1.7 has been the focus of intense investigation in recent years. Human genetics studies of individuals with gain-of-function and loss-of-function mutations in the Nav1.7 channel have implicated Nav1.7 as playing a critical role in pain. Therefore, selective inhibition of Nav1.7 represents a potentially new analgesic strategy that is expected to be devoid of the significant liabilities associated with available treatment options. Although the identification and development of selective Nav channel modulators have historically been challenging, a number of recent publications has demonstrated progression of increasingly subtype-selective small molecules and peptides toward potential use in preclinical or clinical studies...
March 13, 2018: Handbook of Experimental Pharmacology
Peng Yu, Lili Hu, Jinyan Xie, Sisi Chen, Lin Huang, Zixuan Xu, Xiao Liu, Qiongqiong Zhou, Ping Yuan, Xia Yan, Jiejin Jin, Yang Shen, Wengen Zhu, Linghua Fu, Qi Chen, Jianhua Yu, Jianxin Hu, Qing Cao, Rong Wan, Kui Hong
BACKGROUND: Cardiovascular complications are major causes of mortality and morbidity in diabetic patients. The mechanisms underlying the progression of diabetic heart (DH) to ventricular arrhythmias are unclear. O-linked GlcNAcylation (O-GlcNAc) is a reversible post-translational modification for the regulation of diverse cellular processes. The purpose of this study was to assess whether the cardiac voltage-gated sodium channel (Nav1.5) is subjected to O-linked GlcNAcylation (O-GlcNAc), which plays an essential role in DH-induced arrhythmias...
February 27, 2018: International Journal of Cardiology
Bingji Jin, Hong Jin
The epithelial sodium channel (ENaC) and mitogen-activated protein kinase (MAPK) pathway have been reported to be associated with the progression of acute lung injury (ALI). Oxymatrine (OMT) alone or combined with other drugs can ameliorate paraquat- or oleic acid-induced lung injury. However, the effect of OMT on lipopolysaccharide (LPS)-induced ALI remains unknown. The aim of the present study was to evaluate whether OMT can attenuate LPS-induced ALI through regulation of the ENaC and MAPK pathway using an ALI mouse model...
March 9, 2018: Experimental Animals
Jin-Jun Wu, Zhen-Zhen Guo, Yuan-Feng Zhu, Zhi-Jian Huang, Xia Gong, Yu-Huan Li, Wen-Jie Son, Xiao-Yan Li, Yan-Mei Lou, Li-Jun Zhu, Lin-Lin Lu, Zhong-Qiu Liu, Liang Liu
BACKGROUND: Fuzi, which is the processed lateral roots of Aconitum carmichaeli Debx. (Ranunculaceae), is a traditional herbal medicine that is well known for its excellent pharmacological effects and acute toxicity. Aconitum alkaloids are responsible for its pharmacological activity and toxicity. Although a large number of studies on Fuzi have been reported, no comprehensive review on its pharmacokinetics has yet been published. PURPOSE: This paper seeks to present a comprehensive review regarding the phytochemistry, pharmacokinetic features and toxicity of Fuzi...
March 1, 2018: Phytomedicine: International Journal of Phytotherapy and Phytopharmacology
Wenqin Hu, Bruce P Bean
Voltage-dependent conductances not only drive action potentials but also help regulate neuronal resting potential. We found differential regulation of resting potential in the proximal axon of layer 5 pyramidal neurons compared to the soma. Axonal resting potential was more negative than the soma, reflecting differential control by multiple voltage-dependent channels, including sodium channels, Cav3 channels, Kv7 channels, and HCN channels. Kv7 current is highly localized to the axon and HCN current to the soma and dendrite...
March 3, 2018: Neuron
Martin Loynaz Prieto, Kamyar Firouzi, Butrus T Khuri-Yakub, Merritt Maduke
Ultrasound (US) can modulate the electrical activity of the excitable tissues, but the mechanisms underlying this effect are not understood at the molecular level or in terms of the physical modality through which US exerts its effects. Here, we report an experimental system that allows for stable patch-clamp recording in the presence of US at 43 MHz, a frequency known to stimulate neural activity. We describe the effects of US on two ion channels proposed to be involved in the response of excitable cells to US: the mechanosensitive Piezo1 channel and the voltage-gated sodium channel NaV 1...
March 7, 2018: Ultrasound in Medicine & Biology
Diana João Fonseca, Manuel Joaquim Vaz da Silva
INTRODUCTION AND OBJECTIVES: The importance of sodium channels for the normal electrical activity of the heart is emphasized by the fact that mutations (inherited or de novo) in genes that encode for these channels or their associated proteins cause arrhythmogenic syndromes such as the Brugada syndrome and the long QT syndrome (LQTS). The aim of this study is to conduct a review of the literature on the mutations in the sodium channel complex responsible for heart disease and the implications of a close relationship between genetics and the clinical aspects of the main cardiac channelopathies, namely at the level of diagnosis, risk stratification, prognosis, screening of family members and treatment...
March 7, 2018: Portuguese Journal of Cardiology: An Official Journal of the Portuguese Society of Cardiology
Paul Hendrickse, Magdalena Galinska, Emma Hodson-Tole, Hans Degens
A large part of age-related muscle wasting is due to incomplete reinnervation of fibres that have become denervated following motoneuron loss. Neural cell adhesion molecule (NCAM) and sodium channel NaV1.5 are considered markers for denervation, but the time course of changes in their expression following denervation has never been systematically evaluated in young-adult and old muscle. To assess the time course of denervation-induced changes in their expression, the left gastrocnemius muscle in 15 young-adult (5-month) and 10 old (25-month) male Wistar rats was denervated for 1, 2 or 4 weeks, while the right muscle served as an internal control...
March 7, 2018: Experimental Gerontology
Ning Xu, Yingying Zheng, Xiaochen Wang, Terry A Krulwich, Yanhe Ma, Jun Liu
Corynebacterium glutamicum is generally regarded as a moderately salt-alkali-tolerant industrial organism. However, relatively little is known about the molecular mechanisms underlying these specific adaptations. Here, we found that the Mrp1 antiporter played crucial roles in conferring both environmental Na+ -resistance and alkali-tolerance, whereas the Mrp2 antiporter was necessary in coping with high KCl stress at alkaline pH. Furthermore, the Δ mrp1mrp2 double mutant showed most severe growth retardation, and failed to grow under high salt or alkaline conditions...
March 9, 2018: Applied and Environmental Microbiology
Eugen Brailoiu, Christine L Barlow, Servio H Ramirez, Mary E Abood, G Cristina Brailoiu
Platelet-activating factor (PAF) is a potent phospholipid mediator that exerts various pathophysiological effects by interacting with a G protein-coupled receptor. PAF has been reported to increase the permeability of the blood-brain barrier (BBB) via incompletely characterized mechanisms. We investigated the effect of PAF on rat brain microvascular endothelial cells (RBMVEC), a critical component of the BBB. PAF produced a dose-dependent increase in cytosolic Ca2+ concentration; the effect was prevented by the PAF receptor antagonist, WEB2086...
March 6, 2018: Neuroscience
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