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Ion Channels

Zhen Lei, Abdul Sami Shaikh, Wenshuai Zheng, Xiao Yu, Jingui Yu, Jingxin Li
Itch, the unpleasant sensation that evokes a desire to scratch, accompanies numerous skin and nervous system disorders. However, the molecular mechanisms of itch are unclear. Acid sensing ion channel 3 (ASIC3) is a sensor of acidic and primary inflammatory pain. The whole-cell patch-clamp technique was used to determine the effect of Chloroquine (CQ)on ASICs currents in primary sensory neurons or the Chinese hamster ovary (CHO) cells transfected with rat-ASIC1a or- ASIC3. Site-directed mutagenesis of plasmid was performed...
October 22, 2016: Journal of Neurochemistry
Kirilka Mladenova, Svetla D Petrova, Tonya D Andreeva, Veselina Moskova-Doumanova, Tanya Topouzova-Hristova, Yuri Kalvachev, Konstantin Balashev, Shomi S Bhattacharya, Christina Chakarova, Zdravko Lalchev, Jordan A Doumanov
Human bestrophin-1 (hBest1) is a transmembrane calcium-activated chloride channel protein - member of the bestrophin family of anion channels, predominantly expressed in the membrane of retinal pigment epithelium (RPE) cells. Mutations in the protein cause ocular diseases, named Bestrophinopathies. Here, we present the first Fourier transform infrared (FTIR) study of the secondary structure elements of hBest1, π/A isotherms and hysteresis, Brewster angle microscopy (BAM) and atomic force microscopy (AFM) visualization of the aggregation state of protein molecules dispersed as Langmuir and Langmuir-Blodgett films...
October 13, 2016: Colloids and Surfaces. B, Biointerfaces
Peter S Shen, Xiaoyong Yang, Paul G DeCaen, Xiaowen Liu, David Bulkley, David E Clapham, Erhu Cao
The Polycystic Kidney Disease 2 (Pkd2) gene is mutated in autosomal dominant polycystic kidney disease (ADPKD), one of the most common human monogenic disorders. Here, we present the cryo-EM structure of PKD2 in lipid bilayers at 3.0 Å resolution, which establishes PKD2 as a homotetrameric ion channel and provides insight into potential mechanisms for its activation. The PKD2 voltage-sensor domain retains two of four gating charges commonly found in those of voltage-gated ion channels. The PKD2 ion permeation pathway is constricted at the selectivity filter and near the cytoplasmic end of S6, suggesting that two gates regulate ion conduction...
October 20, 2016: Cell
Benoîte Bourdin, Emilie Segura, Marie-Philippe Tétreault, Sylvie Lesage, Lucie Parent
Inherited or de novo mutations in cation-selective channels may lead to sudden cardiac death. Alteration in the plasma membrane trafficking of these multi-spanning transmembrane proteins, with or without change in channel gating, is often postulated to contribute significantly in this process. It has thus become critical to develop a method to quantify the change of the relative cell surface expression of cardiac ion channels on a large scale. Herein, a detailed protocol is provided to determine the relative total and cell surface expression of cardiac L-type calcium channels CaV1...
September 28, 2016: Journal of Visualized Experiments: JoVE
Wenqi Yang, Wei Zhang, Xiaoxue Wang
The plant phytohormone abscisic acid (ABA) plays significant roles in integrating environmental signals with embryogenesis, germination, seedling establishment, the floral transition, and the adaptation of plants to stressful environments by modulating stomatal movement and stress-responsive gene expression. ABA signaling consists of ABA perception, signal transduction, and ABA-induced responses. ABA receptors such as members of the PYR/PYL family, group A type 2C protein phosphatases (as negative regulators), SnRK2 protein kinases (as positive regulators), bZIP transcription factors, and ion channels are key components of ABA signaling...
October 21, 2016: Plant Biotechnology Journal
Thomas Pannicke, T Ivo Chao, Miriam Reisenhofer, Mike Francke, Andreas Reichenbach
Müller cells are the dominant macroglial cells in the retina of all vertebrates. They fulfill a variety of functions important for retinal physiology, among them spatial buffering of K(+) ions and uptake of glutamate and other neurotransmitters. To this end, Müller cells express inwardly rectifying K(+) channels and electrogenic glutamate transporters. Moreover, a lot of voltage- and ligand-gated ion channels, aquaporin water channels, and electrogenic transporters are expressed in Müller cells, some of them in a species-specific manner...
October 21, 2016: Glia
Derek Garden, Arianna Rinaldi, Matthew F Nolan
The inferior olive plays a critical role in motor coordination and learning by integrating diverse afferent signals to generate climbing fibre inputs to the cerebellar cortex. While it is well established that climbing fibre signals are important for motor coordination, the mechanisms by which neurones in the inferior olive integrate synaptic inputs and the roles of particular ion channels are unclear. Here, we test the hypothesis that neurones in the inferior olive actively integrate glutamatergic synaptic inputs...
October 21, 2016: Journal of Physiology
Jiyu Hu, Feng Qian, Guosheng Song, Wenyao Li, Linlin Wang
Large-area ultrafine MnO2 nanowire arrays (NWA) directly grew on a carbon fiber (CF, used as a substrate) by a simple electrochemical method, forming three-dimensional (3D) hierarchical heterostructures of a CF@MnO2 NWA composite. As an electrode for supercapacitors, the CF@MnO2 NWA composite exhibits excellent electrochemical performances including high specific capacitance (321.3 F g(-1) at 1000 mA g(-1)) and good rate capability. Further, the overall capacitance retention is ~99.7 % capacitance after 3000 cycles...
December 2016: Nanoscale Research Letters
Cosmo Godino, Antonio Colombo, Alberto Margonato
Heart rate is an established prognostic marker for longevity and is an important contributor in the pathophysiology of various cardiovascular diseases, including ischemic heart disease and heart failure. Most ischemic episodes are triggered by an increase in heart rate, which causes an imbalance between myocardial oxygen delivery and consumption. In addition, increased heart rate is a modifiable risk factor for chronic heart failure. Ivabradine, an inhibitor of If ion channels, is an approved second-line anti-ischemic drug for the treatment of angina...
October 21, 2016: Clinical Drug Investigation
Lois Choy, Jie Ming Yeo, Vivian Tse, Shing Po Chan, Gary Tse
The mouse is the second mammalian species, after the human, in which substantial amount of the genomic information has been analyzed. With advances in transgenic technology, mutagenesis is now much easier to carry out in mice. Consequently, an increasing number of transgenic mouse systems have been generated for the study of cardiac arrhythmias in ion channelopathies and cardiomyopathies. Mouse hearts are also amenable to physical manipulation such as coronary artery ligation and transverse aortic constriction to induce heart failure, radiofrequency ablation of the AV node to model complete AV block and even implantation of a miniature pacemaker to induce cardiac dyssynchrony...
September 2016: IJC Heart & Vasculature
Jing Zhang, You Wang, Kai-Ming Sun, Kuan Fang, Xuexi Tang
Polybrominated diphenyl ethers (PBDEs) are widely dispersed persistent organic pollutants in the marine ecosystem. However, their toxic mechanisms in marine organisms, especially invertebrates, remain poorly understood. Two common congeners of PBDEs, tetrabrominated diphenyl ether-47 (BDE-47) and decabrominated diphenyl ether-209 (BDE-209), were investigated. Their toxic mechanisms, with a focus on oxidative stress, were examined in rotifer Brachionus plicatilis. Overproduction of reactive oxygen species (ROS) was induced by two PBDEs...
October 17, 2016: Marine Pollution Bulletin
Tao Hou, Weiwei Liu, Wen Shi, Zhili Ma, Hui He
The structure of the desalted duck egg white peptides-calcium chelate was characterized by fluorescence spectroscopy, fourier transform infrared spectroscopy, and dynamic light scattering. Characterization results showed structural folding and aggregation of amino acids or oligopeptides during the chelation process. Desalted duck egg white peptides enhanced the calcium uptake in the presence of oxalate, phosphate and zinc ions in Caco-2 monolayers. Animal model indicated that desalted duck egg white peptides effectively enhanced the mineral absorption and counteracted the deleterious effects of phytic acid...
March 15, 2017: Food Chemistry
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
Sergio Valbuena, Juan Lerma
Neurotransmitter receptors are responsible for the transfer of information across the synapse. While ionotropic receptors form ion channels and mediate rapid membrane depolarization, so-called metabotropic receptors exert their action though slower, less direct intracellular signaling pathways. Glutamate, GABA, and acetylcholine can activate both ionotropic and metabotropic receptors, yet the distinction between these "canonical" signaling systems has become less clear since ionotropic receptors were proposed to also activate second messenger systems, defining a "non-canonical" signaling pathway...
October 19, 2016: Neuron
Jacopo Celli, Gudrun Rappold, Beate Niesler
Serotonin type 3 (5-HT3 ) receptors are ligand-gated ion channels formed by five subunits (5-HT3 A-E), which are encoded by the HTR3A, HTR3B, HTR3C, HTR3D and HTR3E genes. Functional receptors are pentameric complexes of diverse composition. Different receptor subtypes confer a predisposition to nausea and vomiting during chemotherapy, pregnancy, and following surgery. In addition, different subtypes contribute to neurogastroenterologic disorders such irritable bowel syndrome (IBS) and eating disorders as well as comorbid psychiatric conditions...
October 20, 2016: Human Mutation
Mordjane Boukhet, Fabien Piguet, Hadjer Ouldali, Manuela Pastoriza-Gallego, Juan Pelta, Abdelghani Oukhaled
The transport of macromolecules through nanopores is involved in many biological functions and is today at the basis of promising technological applications. Nevertheless the interpretation of the dynamics of the macromolecule/nanopore interaction is still misunderstood and under debate. At the nanoscale, inside biomimetic channels under an external applied voltage, electrophoresis, which is the electric force acting on electrically charged molecules, and electroosmotic flow (EOF), which is the fluid transport associated with ions, contribute to the direction and magnitude of the molecular transport...
October 20, 2016: Nanoscale
Samuel A Neymotin, Benjamin A Suter, Salvador Dura-Bernal, Gordon M G Shepherd, Michele Migliore, William W Lytton
Corticospinal neurons (SPI), thick-tufted pyramidal neurons in motor cortex layer 5B that project caudally via the medullary pyramids, display distinct class-specific electrophysiological properties in vitro: strong sag with hyperpolarization, lack of adaptation, and a nearly linear frequency-current (FI) relationship. We used our electrophysiological data to produce a pair of large archives of SPI neuron computer models in two model classes: 1. Detailed models with full reconstruction; 2. Simplified models with 6 compartments...
October 19, 2016: Journal of Neurophysiology
Haitao Yu, Rishi R Dhingra, Thomas E Dick, Roberto Fernandez Galan
Neural activity generally displays irregular firing patterns even in circuits with apparently regular outputs, such as motor pattern generators, in which the output frequency fluctuates randomly around a mean value. This "circuit noise" is inherited from the random firing of single neurons, which emerges from stochastic ion-channel gating (channel noise), spontaneous neurotransmitter release, and its diffusion and binding to synaptic receptors. Here, we demonstrate how to expand conductance-based network models that are originally deterministic to include realistic, physiological noise, focusing on stochastic ion-channel gating...
October 19, 2016: Journal of Neurophysiology
Maksim Storozhuk, Elena Kondratskaya, Lyudmila Nikolaenko, Oleg Krishtal
Rapid acidification occurring during synaptic vesicle release can activate acid-sensing ion channels (ASICs) both on pre- and postsynaptic neurons. In the latter case, a fraction of postsynaptic current would be mediated by cation-selective acid-sensing ion channels. Additionally, in both cases, activation of acid-sensing ion channels could modulate synaptic strength by affecting transmitter release and/or sensitivity of postsynaptic receptors. To address potential involvement of acid-sensing ion channels in mediation/modulation of synaptic transmission at hippocampal GABAergic synapses, we studied effects of three structurally different blockers of acid-sensing ion channels on evoked postsynaptic currents using the patch-clamp technique...
October 19, 2016: Molecular Brain
Fredrik Elinder, Michael Madeja, Hugo Zeberg, Peter Århem
The transmembrane voltage needed to open different voltage-gated K (Kv) channels differs by up to 50 mV from each other. In this study we test the hypothesis that the channels' voltage dependences to a large extent are set by charged amino-acid residues of the extracellular linkers of the Kv channels, which electrostatically affect the charged amino-acid residues of the voltage sensor S4. Extracellular cations shift the conductance-versus-voltage curve, G(V), by interfering with these extracellular charges...
October 18, 2016: Biophysical Journal
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