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Sodium channels

Nicole A Hawkins, Nicole J Zachwieja, Alison R Miller, Lyndsey L Anderson, Jennifer A Kearney
A substantial number of mutations have been identified in voltage-gated sodium channel genes that result in various forms of human epilepsy. SCN1A mutations result in a spectrum of severity ranging from mild febrile seizures to Dravet syndrome, an infant-onset epileptic encephalopathy. Dravet syndrome patients experience multiple seizures types that are often refractory to treatment, developmental delays, and elevated risk for SUDEP. The same sodium channel mutation can produce epilepsy phenotypes of varying clinical severity...
October 2016: PLoS Genetics
Jinping Shao, Jing Cao, Jiannan Wang, Xiuhua Ren, Songxue Su, Ming Li, Zhihua Li, Qingzan Zhao, Weidong Zang
Voltage-gated sodium channels, which are involved in pain pathways, have emerged as major targets for therapeutic intervention in pain disorders. Nav1.7, the tetrodotoxin-sensitive voltage-gated sodium channel isoform encoded by SCN9A and predominantly expressed in pain-sensing neurons in the dorsal root ganglion, plays a crucial role in nociception. MicroRNAs are highly conserved, small non-coding RNAs. Through binding to the 3' untranslated region of their target mRNAs, microRNAs induce the cleavage and/or inhibition of protein translation...
2016: Molecular Pain
Fahima Syeda, Andrew P Holmes, Ting Y Yu, Samantha Tull, Stefan Michael Kuhlmann, Davor Pavlovic, Daniel Betney, Genna Riley, Jan P Kucera, Florian Jousset, Joris R de Groot, Stephan Rohr, Nigel A Brown, Larissa Fabritz, Paulus Kirchhof
BACKGROUND: Antiarrhythmic drugs are widely used to treat patients with atrial fibrillation (AF), but the mechanisms conveying their variable effectiveness are not known. Recent data suggested that paired like homeodomain-2 transcription factor (PITX2) might play an important role in regulating gene expression and electrical function of the adult left atrium (LA). OBJECTIVES: After determining LA PITX2 expression in AF patients requiring rhythm control therapy, the authors assessed the effects of Pitx2c on LA electrophysiology and the effect of antiarrhythmic drugs...
October 25, 2016: Journal of the American College of Cardiology
Daryl C Yang, Jennifer R Deuis, Daniel Dashevsky, James Dobson, Timothy N W Jackson, Andreas Brust, Bing Xie, Ivan Koludarov, Jordan Debono, Iwan Hendrikx, Wayne C Hodgson, Peter Josh, Amanda Nouwens, Gregory J Baillie, Timothy J C Bruxner, Paul F Alewood, Kelvin Kok Peng Lim, Nathaniel Frank, Irina Vetter, Bryan G Fry
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...
October 18, 2016: Toxins
Krishnan Mugundhan, Rajesh Shankar Iyer
Cypermethrin is a synthetic pyrethroid and pyrimethrin analogue. Cypermethrin poisoning produces neurological manifestations due to its primary target on sodium channels.1 Neuropathy following cypermethrin poisoning is common. But myelopathy is rare and not reported so far. We report a 17 year old healthy male who developed myelopathy following cypermethrin ingestion. The possible mechanism for the myelopathy in this patient is discussed.
September 2016: Journal of the Association of Physicians of India
Yong Cui, Huiming Li, Sihui Wu, Runzhen Zhao, Deyi Du, Yan Ding, Hongguang Nie, Hong-Long Ji
Unsaturated oxidative formaldehyde is a noxious aldehyde in cigarette smoke that causes edematous acute lung injury. However, the mechanistic effects of formaldehyde on lung fluid transport are still poorly understood. We examined how formaldehyde regulates human epithelial sodium channels (ENaC) in H441 and expressed in Xenopus oocytes and exposed mice in vivo. Our results showed that formaldehyde reduced mouse transalveolar fluid clearance in vivo. Formaldehyde caused a dose-dependent inhibition of amiloride-sensitive short-circuit Na(+) currents in H441 monolayers and of αβγ-ENaC channel activity in oocytes...
October 20, 2016: Scientific Reports
Anna Keppner, Sumedha Malsure, Antoine Nobile, Muriel Auberson, Olivier Bonny, Edith Hummler
BACKGROUND: Inflammatory bowel diseases (IBD) including ulcerative colitis and Crohn's disease are diseases with impaired epithelial barrier function. We aimed to investigate whether mutated prostasin and thus, reduced colonic epithelial sodium channel activity predisposes to develop an experimentally dextran sodium sulfate (DSS)-induced colitis. METHODS: Wildtype, heterozygous (fr/+), and homozygous (fr/fr) prostasin-mutant rats were treated 7 days with DSS followed by 7 days of recovery and analyzed with respect to histology, clinicopathological parameters, inflammatory marker mRNA transcript expression, and sodium transporter protein expression...
October 12, 2016: Inflammatory Bowel Diseases
Francisco J Rios, Katie Y Hood, A Karvey, Karla B Neves, Panagiota Anyfanti, Ryszard Nosalski, Livia L Camargo Ll, Augusto C Montezano, Rhian M Touyz
OBJECTIVE: TRPM7 is cation channel with intrinsic kinase activity important for cellular Mg homeostasis. We recently showed that TRPM7-kinase plays a role in aldosterone-mediated vascular effects and inflammation. Here we explored the putative role of TRPM7-kinase in cardiac fibrosis and vascular function in aldosterone-induced hypertension in mice. DESIGN AND METHOD: Wild-type (WT) or heterozygote TRPM7-kinase domain (TRPM7+/-) mice were treated with infused aldosterone (600 μg/Kg/day) and NaCl 1% in drinking water (aldo/salt) for 4 weeks...
September 2016: Journal of Hypertension
Cesar Romero, Sumit Monu, Glauber Cabral, Robert Knight, Oscar Carretero
OBJECTIVE: Renal hemodynamics is critical for regulation of glomerular filtration (GFR), sodium excretion and blood pressure (BP), and it depends on myogenic response, tubuloglomerular feedback (TGF) and connecting tubule-glomerular feedback (CTGF). CTGF dilates afferent arteriole in response to high sodium in connecting tubule (CNT), counteracting and resetting TGF; and increasing the plasma flow and glomerular pressure favoring sodium excretion. CTGF is initiated by epithelial sodium channel (ENaC) activation in CNT and inhibited by ENaC blocker Benzamil...
September 2016: Journal of Hypertension
Michal Behuliak, Michal Bencze, Anna Vavrinova, Ivana Vaneckova, Josef Zicha
OBJECTIVE: Voltage-dependent calcium channels (VDCCs) play an important role in two major abnormalities observed in spontaneously hypertensive rats (SHR) - hyperactivity of sympathetic nervous system (SNS) and enhanced Ca influx to vascular smooth muscle cells (VSMC). α2δ subunit of VDCC, which promotes surface trafficking and modulates the biophysical properties of VDCC, was identified as a critical component of increased L-type VDCC calcium currents in arterial myocytes of SHR. On the other hand, N-type VDCCs control a neurotransmitter release in the peripheral sympathetic nervous system and play an important role in sympathetic hyperactivity in SHR...
September 2016: Journal of Hypertension
David John Webb
Treatment-resistant hypertension (TRH) is defined as the failure to achieve an office BP target of <140/90 mmHg (<130/80 mmHg in patients with chronic kidney disease (CKD) or diabetes) in patients with hypertension (HT), despite adherence to at least 3 antihypertensive medications at optimal tolerated doses, ideally including a diuretic (Calhoun et al., Circulation 2008). TRH identifies patients with hard-to-treat HT, who might benefit from specialist investigation and treatment. Although some studies put the prevalence of TRH as >10%, these levels may be inflated by white-coat hypertension and poor adherence...
September 2016: Journal of Hypertension
Hung X Nguyen, Robert D Kirkton, Nenad Bursac
The ability to directly enhance electrical excitability of human cells is hampered by the lack of methods to efficiently overexpress large mammalian voltage-gated sodium channels (VGSC). Here we describe the use of small prokaryotic sodium channels (BacNav) to create de novo excitable human tissues and augment impaired action potential conduction in vitro. Lentiviral co-expression of specific BacNav orthologues, an inward-rectifying potassium channel, and connexin-43 in primary human fibroblasts from the heart, skin or brain yields actively conducting cells with customizable electrophysiological phenotypes...
October 18, 2016: Nature Communications
Michela De Bellis, Roberta Carbonara, Julien Roussel, Alessandro Farinato, Ada Massari, Sabata Pierno, Marilena Muraglia, Filomena Corbo, Carlo Franchini, Maria Rosaria Carratù, Annamaria De Luca, Diana Conte Camerino, Jean-François Desaphy
Although the sodium channel blocker, mexiletine, is the first choice drug in myotonia, some myotonic patients remain unsatisfied due to contraindications, lack of tolerability, or incomplete response. More therapeutic options are thus needed for myotonic patients, which require clinical trials based on solid preclinical data. In previous structure-activity relationship studies, we identified two newly-synthesized derivatives of tocainide, To040 and To042, with greatly enhanced potency and use-dependent behavior in inhibiting sodium currents in frog skeletal muscle fibers...
October 12, 2016: Neuropharmacology
Salzitsa Anastasova, Blair Crewther, Pawel Bembnowicz, Vincenzo Curto, Henry Md Ip, Bruno Rosa, Guang-Zhong Yang
In sport, exercise and healthcare settings, there is a need for continuous, non-invasive monitoring of biomarkers to assess human performance, health and wellbeing. Here we report the development of a flexible microfluidic platform with fully integrated sensing for on-body testing of human sweat. The system can simultaneously and selectively measure metabolite (e.g. lactate) and electrolytes (e.g. pH, sodium) together with temperature sensing for internal calibration. The construction of the platform is designed such that continuous flow of sweat can pass through an array of flexible microneedle type of sensors (50µm diameter) incorporated in a microfluidic channel...
September 21, 2016: Biosensors & Bioelectronics
Letícia B Smith, Shinji Kasai, Jeffrey G Scott
Aedes aegypti and A. albopictus mosquitoes are vectors of important human disease viruses, including dengue, yellow fever, chikungunya and Zika. Pyrethroid insecticides are widely used to control adult Aedes mosquitoes, especially during disease outbreaks. Herein, we review the status of pyrethroid resistance in A. aegypti and A. albopictus, mechanisms of resistance, fitness costs associated with resistance alleles and provide suggestions for future research. The widespread use of pyrethroids has given rise to many populations with varying levels of resistance worldwide, albeit with substantial geographical variation...
October 2016: Pesticide Biochemistry and Physiology
Ehud Chorin, Dan Hu, Charles Antzelevitch, Aviram Hochstadt, Luiz Belardinelli, David Zeltser, Hector Barajas-Martinez, Uri Rozovski, Raphael Rosso, Arnon Adler, Jesaia Benhorin, Sami Viskin
BACKGROUND: The basic defect in long-QT syndrome type III (LQT3) is an excessive inflow of sodium current during phase 3 of the action potential caused by mutations in the SCN5A gene. Most sodium channel blockers reduce the early (peak) and late components of the sodium current (INa and INaL), but ranolazine preferentially reduces INaL. We, therefore, evaluated the effects of ranolazine in LQT3 caused by the D1790G mutation in SCN5A. METHODS AND RESULTS: We performed an experimental study of ranolazine in TSA201 cells expressing the D1790G mutation...
October 2016: Circulation. Arrhythmia and Electrophysiology
Mei Wang, Youyang Hu, Yifei Fan, Yan Guo, Fanglin Chen, Shuo Chen, Qinglin Li, Zhiwu Chen
BACKGROUND/AIM: H2S is a novel vasoactivator. To verify the hypothesis that H2S may act as an endothelium-derived hyperpolarizing factor (EDHF) in the rat cerebrovasculature, the role of H2S in endothelium-derived relaxing factor (EDRF)-mediated responses was investigated. METHODS: Cystathionine-γ-lyase (CSE) was knocked down with an siRNA technique. Artery diameter, hyperpolarization and Ca2+-activated K+ (KCa) current were measured. RESULTS: CSE knockdown was indicated by a decrease in protein and mRNA expression in the rat middle cerebral artery (MCA) and cerebral basilar artery (CBA)...
October 13, 2016: Journal of Vascular Research
Anne-Marie Malfait, Richard J Miller
Worldwide, osteoarthritis (OA) is one of the leading causes of chronic pain, for which adequate relief is not available. Ongoing peripheral input from the affected joint is a major factor in OA-associated pain. Therefore, this review focuses predominantly on peripheral targets emerging in the preclinical and clinical arena. Nerve growth factor is the most advanced of these targets, and its blockade has shown tremendous promise in clinical trials in knee OA. A number of different types of ion channels, including voltage-gated sodium channels and calcium channels, transient receptor potential channels, and acid-sensing ion channels, are important for neuronal excitability and play a role in pain genesis...
October 12, 2016: Current Osteoporosis Reports
Benjamin D Menze, Jacob M Riveron, Sulaiman S Ibrahim, Helen Irving, Christophe Antonio-Nkondjio, Parfait H Awono-Ambene, Charles S Wondji
BACKGROUND: Despite the recent progress in establishing the patterns of insecticide resistance in the major malaria vector Anopheles funestus, Central African populations of this species remain largely uncharacterised. To bridge this important gap and facilitate the implementation of suitable control strategies against this vector, we characterised the resistance patterns of An. funestus population from northern Cameroon. METHODS AND FINDINGS: Collection of indoor-resting female mosquitoes in Gounougou (northern Cameroon) in 2012 and 2015 revealed a predominance of An...
2016: PloS One
S A Coavoy-Sánchez, L Rodrigues, S A Teixeira, A G Soares, R Torregrossa, M E Wood, M Whiteman, S K P Costa, M N Muscará
Hydrogen sulfide (H2S) has been highlighted as an endogenous signaling molecule and we have previously found that it can inhibit histamine-mediated itching. Pruritus is the most common symptom of cutaneous diseases and anti-histamines are the usual treatment; however, anti-histamine-resistant pruritus is common in some clinical settings. In this way, the involvement of mediators other than histamine in the context of pruritus requires new therapeutic targets. Considering that the activation of proteinase-activated receptor 2 (PAR-2) is involved in pruritus both in rodents and humans, in this study we investigated the effect of H2S donors on the acute scratching behavior mediated by PAR-2 activation in mice, as well as some of the possible pharmacological mechanisms involved...
October 6, 2016: Pharmacological Research: the Official Journal of the Italian Pharmacological Society
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