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Hyperpolarization

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https://www.readbyqxmd.com/read/28213919/diuretic-sensitive-electroneutral-na-movement-and-temperature-effects-on-central-axons
#1
Meneka Kanagaratnam, Christopher Pendleton, Danilo Almeida Souza, Joseph Pettit, James Howells, Mark D Baker
Raising the temperature of optic nerve from room temperature to near physiological has effects on the threshold, refractoriness and superexcitability of the shortest latency (fast, F) nerve fibres, consistent with hyperpolarization. The temperature dependence of peak impulse latency was weakened at temperatures above 30°C suggesting a temperature sensitive process that slows impulse propagation. The amplitude of the supramaximal compound action potential gets larger on warming, whereas in the presence of bumetanide and amiloride (blockers of electroneutral Na(+) movement), the action potential amplitude consistently falls...
February 17, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28213518/deficits-in-the-activity-of-presynaptic-%C3%AE-aminobutyric-acid-type-b-receptors-contribute-to-altered-neuronal-excitability-in-fragile-x-syndrome
#2
Ji-Yong Kang, Jayashree Chadchankar, Thuy N Vien, Michelle I Mighdoll, Thomas M Hyde, Robert J Mather, Tarek Z Deeb, Menelas N Pangalos, Nicholas J Brandon, John Dunlop, Stephen J Moss
The behavioral and anatomical deficits seen in Fragile X syndrome (FXS) are widely believed to result from imbalances in the relative strengths of excitatory and inhibitory neurotransmission. While modified neuronal excitability is thought to be of significance, the contribution that alterations in GABAergic inhibition play in the pathophysiology of FXS are ill-defined. Slow sustained neuronal inhibition is mediated by γ-aminobutyric acid type B (GABAB) receptors, which are heterodimeric G-protein coupled receptors constructed from R1a and R2 or R1b and R2 subunits...
February 17, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28213444/the-dendrites-of-ca2-and-ca1-pyramidal-neurons-differentially-regulate-information-flow-in-the-cortico-hippocampal-circuit
#3
Kalyan V Srinivas, Eric W Buss, Qian Sun, Bina Santoro, Hiroto Takahashi, Daniel A Nicholson, Steven A Siegelbaum
The impact of a given neuronal pathway depends on the number of synapses it makes with its postsynaptic target, the strength of each individual synapse and the integrative properties of the postsynaptic dendrites. Here we explore the cellular and synaptic mechanisms responsible for the differential excitatory drive from the entorhinal cortical pathway onto mouse CA2 compared to CA1 pyramidal neurons (PNs). Although both types of neurons receive direct input from entorhinal cortex onto their distal dendrites, these inputs produce a 5-6 fold larger excitatory postsynaptic potential (EPSP) at the soma of CA2 compared to CA1 PNs, which is sufficient to drive action potential output from CA2 but not CA1...
February 17, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28212823/cyp-epoxygenase-derived-h2o2-is-involved-in-the-endothelium-derived-hyperpolarization-edh-and-relaxation-of-intrarenal-arteries
#4
Mercedes Muñoz, Maria Elvira López-Oliva, Estéfano Pinilla, María Pilar Martínez, Ana Sánchez, Claudia Rodríguez, Albino García-Sacristán, Medardo Hernández, Luis Rivera, Dolores Prieto
Reactive oxygen species (ROS) like hydrogen peroxide (H2O2) are involved in the in endothelium-derived hyperpolarization (EDH)-type relaxant responses of coronary and mesenteric arterioles. The role of ROS in kidney vascular function has mainly been investigated in the context of harmful ROS generation associated to kidney disease. The present study was sought to investigate whether H2O2 is involved in the endothelium-dependent relaxations of intrarenal arteries as well the possible endothelial sources of ROS generation involved in these responses...
February 14, 2017: Free Radical Biology & Medicine
https://www.readbyqxmd.com/read/28202574/action-potentials-and-ion-conductances-in-wild-type-and-calhm1-knockout-type-ii-taste-cells
#5
Zhongming Ma, Wint Thu Saung, J Kevin Foskett
Taste bud type II cells fire action potentials in response to tastants, triggering non-vesicular ATP release to gustatory neurons via voltage-gated CALHM1-associated ion channels. Whereas CALHM1 regulates mouse cortical neuron excitability, its roles in regulating type II cell excitability are unknown. Here, we compared membrane conductances and action potentials in single identified TRPM5-GFP-expressing circumvallate papillae type II cells acutely isolated from wild-type (WT) and Calhm1-knockout (KO) mice...
February 15, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/28197549/activation-dependent-rapid-postsynaptic-clustering-of-glycine-receptors-in-mature-spinal-cord-neurons
#6
Yoshihisa Nakahata, Kei Eto, Hideji Murakoshi, Miho Watanabe, Toshihiko Kuriu, Hiromi Hirata, Andrew J Moorhouse, Hitoshi Ishibashi, Junichi Nabekura
Inhibitory synapses are established during development but continue to be generated and modulated in strength in the mature nervous system. In the spinal cord and brainstem, presynaptically released inhibitory neurotransmitter dominantly switches from GABA to glycine during normal development in vivo. While presynaptic mechanisms of the shift of inhibitory neurotransmission are well investigated, the contribution of postsynaptic neurotransmitter receptors to this shift is not fully elucidated. Synaptic clustering of glycine receptors (GlyRs) is regulated by activation-dependent depolarization in early development...
January 2017: ENeuro
https://www.readbyqxmd.com/read/28197106/inhibition-of-intermediate-conductance-calcium-activated-k-channel-kca3-1-and-fibroblast-mitogenesis-by-%C3%AE-linolenic-acid-and-alterations-of-channel-expression-in-the-lysosomal-storage-disorders-fabry-disease-and-niemann-pick-c
#7
Aida Oliván-Viguera, Javier Lozano-Gerona, Laura López de Frutos, Jorge J Cebolla, Pilar Irún, Edgar Abarca-Lachen, Ana J García-Malinis, Ángel Luis García-Otín, Yolanda Gilaberte, Pilar Giraldo, Ralf Köhler
The calcium/calmodulin-gated KCa3.1 channel regulates normal and abnormal mitogenesis by controlling K(+)-efflux, cell volume, and membrane hyperpolarization-driven calcium-entry. Recent studies suggest modulation of KCa3.1 by omega-3 fatty acids as negative modulators and impaired KCa3.1 functions in the inherited lysosomal storage disorder (LSD), Fabry disease (FD). In the first part of present study, we characterize KCa3.1 in murine and human fibroblasts and test the impact of omega-3 fatty acids on fibroblast proliferation...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/28192930/mitochondria-targeted-and-intracellular-biothiol-triggered-hyperpolarized-129-xe-magnetofluorescent-biosensor
#8
Qingbin Zeng, Qianni Guo, Yaping Yuan, Yuqi Yang, Bin Zhang, Lili Ren, Xiaoxiao Zhang, Qing Luo, Maili Liu, Louis-S Bouchard, Xin Zhou
Biothiols such as gluthathione (GSH), cysteine (Cys), homocysteine (Hcy), and thioredoxin (Trx) play vital roles in cellular metabolism. Various diseases are associated with abnormal cellular biothiol levels. Thus, the intracellular detection of biothiol levels could be a useful diagnostic tool. A number of methods have been developed to detect intracellular thiols, but sensitivity and specificity problems have limited their applications. To address these limitations, we have designed a new biosensor based on hyperpolarized xenon magnetic resonance detection, which can be used to detect biothiol levels noninvasively...
February 9, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28192127/long-term-treatment-with-nandrolone-decanoate-impairs-mesenteric-vascular-relaxation-in-both-sedentary-and-exercised-female-rats
#9
Izabela F Caliman, Cristian S Bernabe, Antônio F de Melo, Girlândia A Brasil, Andrews M do Nascimento, Ewelyne M de Lima, Suely G Figueiredo, Tadeu U de Andrade, Nazaré S Bissoli
Nandrolone Decanoate (ND) is an Anabolic Androgenic Steroid (AAS) that under abusive regimen can lead to multiple physiological adverse effects. Studies of AAS-mediated cardiovascular (CV) alterations were mostly taken from male subjects, even though women are also susceptible to the effects of AAS and gender-specific differences in susceptibility to vascular diseases exist. Here we investigate ND-induced vascular reactivity alterations in both sedentary and exercised female rats and whether these alterations depend on endothelium-derived factors...
February 9, 2017: Steroids
https://www.readbyqxmd.com/read/28191664/direct-arterial-injection-of-hyperpolarized-13-c-labeled-substrates-into-rat-tumors-for-rapid-mr-detection-of-metabolism-with-minimal-substrate-dilution
#10
Steven Reynolds, Stephen Metcalf, Edward J Cochrane, Rebecca C Collins, Simon Jones, Martyn N J Paley, Gillian M Tozer
PURPOSE: A rat model was developed to enable direct administration of hyperpolarized (13) C-labeled molecules into a tumor-supplying artery for magnetic resonance spectroscopy (MRS) studies of tumor metabolism. METHODS: Rat P22 sarcomas were implanted into the right inguinal fat pad of BDIX rats such that the developing tumors received their principle blood supply directly from the right superior epigastric artery. Hyperpolarized (13) C-molecules were either infused directly to the tumor through the epigastric artery or systemically through the contralateral femoral vein...
February 12, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28188927/xanthohumol-isolated-from-humulus-lupulus-prevents-thrombosis-without-increased-bleeding-risk-by-inhibiting-platelet-activation-and-mtdna-release
#11
Guang Xin, Zeliang Wei, Chengjie Ji, Huajie Zheng, Jun Gu, Limei Ma, Wenfang Huang, Susan L Morris-Natschke, Jwu-Lai Yeh, Rui Zhang, Chaoyi Qin, Li Wen, Zhihua Xing, Yu Cao, Qing Xia, Ke Li, Hai Niu, Kuo-Hsiung Lee, Wen Huang
AIM: As the global population has reached 7 billion and the baby boom generation reaches old age, thrombosis has become the major contributor to the global disease burden. It has been reported that, in moderate doses, beer may protect against thrombosis. Xanthohumol (XN), an antioxidant, is found at high concentrations in hop cones (Humulus lupulus L.) and is a common ingredient of beer. Here, the aim of the present work was to investigate the effects of XN on antithrombotic and antiplatelet activities, and study its mechanism...
February 7, 2017: Free Radical Biology & Medicine
https://www.readbyqxmd.com/read/28186677/imaging-porcine-cardiac-substrate-selection-modulations-by-glucose-insulin-and-potassium-intervention-a-hyperpolarized-1-13-c-pyruvate-study
#12
Esben Søvsø Szocska Hansen, Rasmus Stilling Tougaard, Thomas Stokholm Nørlinger, Emmeli Mikkelsen, Per Mose Nielsen, Lotte Bonde Bertelsen, Hans Erik Bøtker, Hans Stødkilde Jørgensen, Christoffer Laustsen
Cardiac metabolism has received considerable attention in terms of both diagnostics and prognostics, as well as a novel target for treatment. As human trials involving hyperpolarized magnetic resonance in the heart are imminent, we sought to evaluate the general feasibility of detection of an imposed shift in metabolic substrate utilization during metabolic modulation with glucose-insulin-potassium (GIK) infusion, and thus the limitations associated with this strategy, in a large animal model resembling human physiology...
February 10, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28183024/high-field-hyperpolarization-exsy-experiment-for-fast-determination-of-dissociation-rates-in-sabre-complexes
#13
Niels K J Hermkens, Martin C Feiters, Floris P J T Rutjes, Sybren S Wijmenga, Marco Tessari
SABRE (Signal Amplification By Reversible Exchange) is a nuclear spin hyperpolarization technique based on the reversible concurrent binding of small molecules and para-hydrogen (p-H2) to an iridium metal complex in solution. At low magnetic field, spontaneous conversion of p-H2 spin order to enhanced longitudinal magnetization of the nuclear spins of the other ligands occurs. Subsequent complex dissociation results in hyperpolarized substrate molecules in solution. The lifetime of this complex plays a crucial role in attained SABRE NMR signal enhancements...
January 21, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/28183023/molecular-dynamics-based-selectivity-for-fast-field-cycling-relaxometry-by-overhauser-and-solid-effect-dynamic-nuclear-polarization
#14
Oliver Neudert, Carlos Mattea, Siegfried Stapf
In the last decade nuclear spin hyperpolarization methods, especially Dynamic Nuclear Polarization (DNP), have provided unprecedented possibilities for various NMR techniques by increasing the sensitivity by several orders of magnitude. Recently, in-situ DNP-enhanced Fast Field Cycling (FFC) relaxometry was shown to provide appreciable NMR signal enhancements in liquids and viscous systems. In this work, a measurement protocol for DNP-enhanced NMR studies is introduced which enables the selective detection of nuclear spin hyperpolarized by either Overhauser effect or solid effect DNP...
January 21, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/28182728/uncovering-sensory-axonal-dysfunction-in-asymptomatic-type-2-diabetic-neuropathy
#15
Jia-Ying Sung, Jowy Tani, Tsui-San Chang, Cindy Shin-Yi Lin
This study investigated sensory and motor nerve excitability properties to elucidate the development of diabetic neuropathy. A total of 109 type 2 diabetes patients were recruited, and 106 were analyzed. According to neuropathy severity, patients were categorized into G0, G1, and G2+3 groups using the total neuropathy score-reduced (TNSr). Patients in the G0 group were asymptomatic and had a TNSr score of 0. Sensory and motor nerve excitability data from diabetic patients were compared with data from 33 healthy controls...
2017: PloS One
https://www.readbyqxmd.com/read/28181007/regulation-of-hcn-ion-channels-by-non-canonical-cyclic-nucleotides
#16
Bryan VanSchouwen, Giuseppe Melacini
The hyperpolarization-activated cyclic-nucleotide-modulated (HCN) proteins are cAMP-regulated ion channels that play a key role in nerve impulse transmission and heart rate modulation in neuronal and cardiac cells, respectively. Although they are regulated primarily by cAMP, other cyclic nucleotides such as cGMP, cCMP, and cUMP serve as partial agonists for the HCN2 and HCN4 isoforms. By competing with cAMP for binding, these non-canonical ligands alter ion channel gating, and in turn, modulate the cAMP-dependent activation profiles...
February 9, 2017: Handbook of Experimental Pharmacology
https://www.readbyqxmd.com/read/28179572/spectrin-%C3%AE-v-adaptive-mutations-and-changes-in-subcellular-location-correlate-with-emergence-of-hair-cell-electromotility-in-mammalians
#17
Matteo Cortese, Samantha Papal, Francisco Pisciottano, Ana Belén Elgoyhen, Jean-Pierre Hardelin, Christine Petit, Lucia Florencia Franchini, Aziz El-Amraoui
The remarkable hearing capacities of mammals arise from various evolutionary innovations. These include the cochlear outer hair cells and their singular feature, somatic electromotility, i.e., the ability of their cylindrical cell body to shorten and elongate upon cell depolarization and hyperpolarization, respectively. To shed light on the processes underlying the emergence of electromotility, we focused on the βV giant spectrin, a major component of the outer hair cells' cortical cytoskeleton. We identified strong signatures of adaptive evolution at multiple sites along the spectrin-βV amino acid sequence in the lineage leading to mammals, together with substantial differences in the subcellular location of this protein between the frog and the mouse inner ear hair cells...
February 8, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28178613/lasalocid-induces-cytotoxic-apoptosis-and-cytoprotective-autophagy-through-reactive-oxygen-species-in-human-prostate-cancer-pc-3-cells
#18
Kwang-Youn Kim, Sang-Hun Kim, Sun-Nyoung Yu, Sul-Gi Park, Young-Wook Kim, Hyo-Won Nam, Hyun-Hee An, Hak-Sun Yu, Young Woo Kim, Jae-Hoon Ji, Young-Kyo Seo, Soon-Cheol Ahn
Lasalocid is an antibiotic from the group of carboxylic ionophores, produced by Streptomyces lasaliensis. But there was limited information of lasalocid on human prostate cancer cells. In the present studies, to better understand its effect in human prostate cancer cells, apoptosis and autophagy associated with possible signal pathways in vitro was examined. Our study showed that lasalocid mediated cell cycle arrest in G0/G1 phase by reducing G1 phase dependent proteins, indicating entering into apoptotic cell death pathway...
February 5, 2017: Biomedicine & Pharmacotherapy, Biomédecine & Pharmacothérapie
https://www.readbyqxmd.com/read/28174302/free-energy-landscape-remodeling-of-the-cardiac-pacemaker-channel-explains-the-molecular-basis-of-familial-sinus-bradycardia
#19
Stephen Boulton, Madoka Akimoto, Sam Akbarizadeh, Giuseppe Melacini
The hyperpolarization-activated and cyclic-nucleotide modulated ion channel (HCN) drives the pacemaker activity in the heart, and its malfunction can result in heart disorders. One such disorder, familial sinus bradycardia, is caused by the S672R mutation in HCN, whose electrophysiological phenotypes include a negative shift in the channel activation voltage and an accelerated HCN deactivation. The outcomes of these changes are abnormally low resting heart rates. However, the molecular mechanism underlying these electrophysiological changes is currently not fully understood...
February 7, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28167233/taste-and-smell-gpcrs-in-the-lung-evidence-for-a-previously-unrecognized-widespread-chemosensory-system
#20
REVIEW
Steven S An, Stephen B Liggett
Taste and smell receptor expression has been traditionally limited to the tongue and nose. We have identified bitter taste receptors (TAS2Rs) and olfactory receptors (ORs) on human airway smooth muscle (HASM) cells. TAS2Rs signal to PLCβ evoking an increase in [Ca(2+)]i causing membrane hyperpolarization and marked HASM relaxation ascertained by single cell, ex vivo, and in vivo methods. The presence of TAS2Rs in the lung was unexpected, as was the bronchodilatory function which has been shown to be due to signaling within specific microdomains of the cell...
February 4, 2017: Cellular Signalling
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