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https://www.readbyqxmd.com/read/28346695/contribution-of-small-conductance-k-channels-to-sinoatrial-node-pacemaker-activity-insights-from-atrial-specific-na-ca-2-exchange-knockout-mice
#1
Angelo G Torrente, Rui Zhang, Heidi Wang, Audrey Zaini, Brian Kim, Xin Yue, Kenneth D Philipson, Joshua I Goldhaber
Small conductance K(+) (SK) channels have been implicated as modulators of spontaneous depolarization and electrical conduction that may be involved in cardiac arrhythmia. However, neither their presence nor their contribution to sinoatrial node (SAN) pacemaker activity have been investigated. Using quantitative PCR (q-PCR), immunostaining and patch clamp recordings of membrane current and voltage, we identified all three SK isoforms (SK1, SK2 and SK3) in mouse SAN. Inhibition of SK channels with the specific blocker apamin prolonged action potentials (APs) in isolated SAN cells...
March 27, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28345117/inwardly-rectifying-k-currents-in-cultured-oligodendrocytes-from-rat-optic-nerve-are-insensitive-to-ph
#2
Alberto Pérez-Samartín, Edith Garay, Juan Pablo H Moctezuma, Abraham Cisneros-Mejorado, María Victoria Sánchez-Gómez, Guadalupe Martel-Gallegos, Leticia Robles-Martínez, Manuel Canedo-Antelo, Carlos Matute, Rogelio O Arellano
Inwardly rectifying K(+) (Kir) channel expression signals at an advanced stage of maturation during oligodendroglial differentiation. Knocking down their expression halts the generation of myelin and produces severe abnormalities in the central nervous system. Kir4.1 is the main subunit involved in the tetrameric structure of Kir channels in glial cells; however, the precise composition of Kir channels expressed in oligodendrocytes (OLs) remains partially unknown, as participation of other subunits has been proposed...
March 27, 2017: Neurochemical Research
https://www.readbyqxmd.com/read/28343377/protein-kinase-c-mediates-the-corticosterone-induced-sensitization-of-dorsal-root-ganglion-neurons-innervating-the-rat-stomach
#3
Meng Li, Lu Xue, Hong-Yan Zhu, Hongjun Wang, Xue Xu, Geping Wu, Guang-Yin Xu
Background/Aims: Gastric hypersensitivity contributes to abdominal pain in patients with functional dyspepsia (FD). Recent studies showed that hormones induced by stress are correlated with visceral hypersensitivity. However, the precise mechanisms underlying gastric hypersensitivity remain largely unknown. The aim of the present study was designed to investigate the roles of corticosterone (CORT) on excitability of dorsal root ganglion (DRG) neurons innervating the stomach. Methods: DRG neurons innervating the stomach were labeled by DiI injection into the stomach wall...
March 26, 2017: Journal of Neurogastroenterology and Motility
https://www.readbyqxmd.com/read/28337126/competition-between-persistent-na-and-muscarine-sensitive-k-currents-shapes-perithreshold-resonance-and-spike-tuning-in-ca1-pyramidal-neurons
#4
Jorge Vera, Julio Alcayaga, Magdalena Sanhueza
Neurons from many brain regions display intrinsic subthreshold theta-resonance, responding preferentially to theta-frequency oscillatory stimuli. Resonance may contribute to selective communication among neurons and to orchestrate brain rhythms. CA1 pyramidal neurons receive theta activity, generating place fields. In these neurons the expression of perithreshold frequency preference is controversial, particularly in the spiking regime, with evidence favoring either non-resonant (integrator-like) or resonant behavior...
2017: Frontiers in Cellular Neuroscience
https://www.readbyqxmd.com/read/28336549/eavk-segment-c-sequence-confers-ca-2-dependent-changes-to-the-kinetics-of-full-length-human-ano1
#5
Peter R Strege, Simon J Gibbons, Amelia Mazzone, Cheryl E Bernard, Arthur Beyder, Gianrico Farrugia
Anoctamin1 (Ano1, TMEM16A) is a calcium-activated chloride channel specifically expressed in interstitial cells of Cajal (ICC) of the gastrointestinal (GI) tract muscularis propria. Ano1 is necessary for normal electrical slow waves and ICC proliferation. The full length human Ano1 sequence includes an additional exon, exon "0," at the N-terminus. Ano1 with exon "0" (Ano1(0)) had a lower EC50 for intracellular calcium ([Ca(2+)]i) and faster chloride current (ICl) kinetics. The Ano1 alternative splice variant with segment "c" encoding exon 13 expresses on the first intracellular loop four additional amino acid residues, EAVK, which alter ICl at low [Ca(2+)]i Exon 13 is expressed in 75-100% of Ano1 transcripts in most human tissues but only 25% in human stomach...
March 23, 2017: American Journal of Physiology. Gastrointestinal and Liver Physiology
https://www.readbyqxmd.com/read/28334404/calcium-homeostasis-modulator-1-like-currents-in-rat-fungiform-taste-cells-expressing-amiloride-sensitive-sodium-currents
#6
Albertino Bigiani
Salt reception by taste cells is still the less understood transduction process occurring in taste buds, the peripheral sensory organs for the detection of food chemicals. Although there is evidence suggesting that the epithelial sodium channel (ENaC) works as sodium receptor, yet it is not clear how salt-detecting cells signal the relevant information to nerve endings. Taste cells responding to sweet, bitter, and umami substances release ATP as neurotransmitter through a nonvesicular mechanism. Three different channel proteins have been proposed as conduit for ATP secretion: pannexin channels, connexin hemichannels, and calcium homeostasis modulator 1 (CALHM1) channels...
March 10, 2017: Chemical Senses
https://www.readbyqxmd.com/read/28334229/functional-and-nonfunctional-forms-of-cquior91-an-odorant-selectivity-subunit-of-culex-quinquefasciatus
#7
David T Hughes, Julien Pelletier, Suhaila Rahman, Sisi Chen, Walter S Leal, Charles W Luetje
In Culex quinquefasciatus, CquiOR91 is the ortholog of 2 larvae-specific odorant receptors (ORs) from Anopheles gambiae (Agam\Or40, previously shown to respond to several odorant ligands including the broad-spectrum repellent N,N-diethyl-3-methylbenzamide, DEET) and Aedes aegypti (Aaeg\Or40). When we cloned full-length CquiOR91 from a Culex quinquefasciatus larval head RNA sample, we found 2 alleles of this OR, differing at 9 residues. Functional analysis using the Xenopus oocyte expression system and 2-electrode voltage clamp electrophysiology revealed one allele (CquiOR91...
March 3, 2017: Chemical Senses
https://www.readbyqxmd.com/read/28331977/role-of-plasma-membrane-associated-akaps-for-the-regulation-of-cardiac-ik1-current-by-protein-kinase-a
#8
Claudia Seyler, Daniel Scherer, Christoph Köpple, Martin Kulzer, Sevil Korkmaz, Panagiotis Xynogalos, Dierk Thomas, Ziya Kaya, Eberhard Scholz, Johannes Backs, Christoph Karle, Hugo A Katus, Edgar Zitron
The cardiac IK1 current stabilizes the resting membrane potential of cardiomyocytes. Protein kinase A (PKA) induces an inhibition of IK1 current which strongly promotes focal arrhythmogenesis. The molecular mechanisms underlying this regulation have only partially been elucidated yet. Furthermore, the role of A-kinase anchoring proteins (AKAPs) in this regulation has not been examined to date. The objective of this project was to elucidate the molecular mechanisms underlying the inhibition of IK1 by PKA and to identify novel molecular targets for antiarrhythmic therapy downstream β-adrenoreceptors...
March 22, 2017: Naunyn-Schmiedeberg's Archives of Pharmacology
https://www.readbyqxmd.com/read/28327344/direct-activation-of-ca-2-and-voltage-gated-potassium-channels-of-large-conductance-by-anandamide-in-endothelial-cells-does-not-support-the-presence-of-endothelial-atypical-cannabinoid-receptor
#9
Alexander I Bondarenko, Olga Panasiuk, Iryna Okhai, Fabrizio Montecucco, Karim J Brandt, Francois Mach
Endocannabinoid anandamide induces endothelium-dependent relaxation commonly attributed to stimulation of the G-protein coupled endothelial anandamide receptor. The study addressed the receptor-independent effect of anandamide on large conductance Ca(2+)-dependent K(+) channels expressed in endothelial cell line EA.hy926. Under resting conditions, 10µM anandamide did not significantly influence the resting membrane potential. In a Ca(2+)-free solution the cells were depolarized by ~10 mV. Further administration of 10µM anandamide hyperpolarized the cells by ~8 mV...
March 19, 2017: European Journal of Pharmacology
https://www.readbyqxmd.com/read/28325835/picomolar-selective-and-subtype-specific-small-molecule-inhibition-of-trpc1-4-5-channels
#10
Hussein N Rubaiy, Melanie J Ludlow, Matthias Henrot, Hannah J Gaunt, Katarina Miteva, Sin Yin Cheung, Yasuyuki Tanahashi, Nurasyikin Hamzah, Katie E Musialowski, Nicola M Blythe, Hollie L Appleby, Marc A Bailey, Lynn McKeown, Roger Taylor, Richard Foster, Herbert Waldmann, Peter Nussbaumer, Mathias Christmann, Robin S Bon, Katsuhiko Muraki, David J Beech
The concentration of free cytosolic Ca(2+) and the voltage across the plasma membrane are major determinants of cell function. Ca(2+)-permeable non-selective cationic channels are known to regulate these parameters but understanding of these channels remains inadequate. Here we focus on Transient Receptor Potential Canonical 4 and 5 proteins (TRPC4 and TRPC5) which assemble as homomers or heteromerize with TRPC1 to form Ca(2+)-permeable non-selective cationic channels in many mammalian cell types. Multiple roles have been suggested including in epilepsy, innate fear, pain and cardiac remodeling but limitations in tools to probe these channels have restricted progress...
March 21, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28325748/halogenated-ether-alcohol-and-alkane-anesthetics-activate-task-3-tandem-pore-potassium-channels-likely-through-a-common-mechanism
#11
Anita Luethy, James D Boghosian, Rithu Srikantha, Joseph Cotten
TASK-3 (KCNK9) tandem pore potassium channel function is activated by halogenated anesthetics through binding at a putative anesthetic binding cavity. To understand pharmacological requirements for TASK-3 activation, we studied the concentration-response of TASK-3 to several anesthetics (isoflurane, desflurane, sevoflurane, halothane, α-chloralose, 2,2,2-trichloroethanol(TCE), and chloral hydrate), to ethanol, and to a panel of halogenated methanes and alcohols. We used mutagenesis to probe the anesthetic binding cavity as observed in a TASK-3 homology model...
March 21, 2017: Molecular Pharmacology
https://www.readbyqxmd.com/read/28323403/discovery-of-potent-antiallodynic-agents-for-neuropathic-pain-targeting-p2x3-receptors
#12
Young-Hwan Jung, Yong-Chul Kim, Yeo Ok Kim, Hai Lin, Joong-Heui Cho, Jin-Hee Park, So-Deok Lee, Jinsu Bae, Koon Mook Kang, Yoon Gyoon Kim, Ae Nim Pae, Hyojin Ko, Chul-Seung Park, Myung Ha Yoon
Antagonism of the P2X3 receptor is one of the potential therapeutic strategies for the management of neuropathic pain because P2X3 receptors are predominantly localized on small to medium diameter C- and Aδ-fiber primary afferent neurons, which are related to the pain-sensing system. In this study, 5-hydroxy pyridine derivatives were designed, synthesized, and evaluated for their in vitro biological activities by two-electrode voltage clamp assay at hP2X3 receptors. Among the novel hP2X3 receptor antagonists, intrathecal treatment of compound 29 showed parallel efficacy with pregabalin (calcium channel modulator) and higher efficacy than AF353 (P2X3 receptor antagonist) in the evaluation of its antiallodynic effects in spinal nerve ligation rats...
March 21, 2017: ACS Chemical Neuroscience
https://www.readbyqxmd.com/read/28322832/dapoxetine-induces-neuroprotective-effects-against-glutamate-induced-neuronal-cell-death-by-inhibiting-calcium-signaling-and-mitochondrial-depolarization-in-cultured-rat-hippocampal-neurons
#13
Imju Jeong, Ji Seon Yang, Yi Jae Hong, Hee Jung Kim, Sang June Hahn, Shin Hee Yoon
Selective serotonin reuptake inhibitors (SSRIs) have an inhibitory effect on various ion channels including Ca(2+) channels. We used fluorescent dye-based digital imaging, whole-cell patch clamping and cytotoxicity assays to examine whether dapoxetine, a novel rapid-acting SSRI, affect glutamate-induced calcium signaling, mitochondrial depolarization and neuronal cell death in cultured rat hippocampal neurons. Pretreatment with dapoxetine for 10min inhibited glutamate-induced intracellular free Ca(2+) concentration ([Ca(2+)]i) increases in a concentration-dependent manner (Half maximal inhibitory concentration= 4...
March 16, 2017: European Journal of Pharmacology
https://www.readbyqxmd.com/read/28322303/a-new-electro-optical-approach-for-conductance-measurement-an-assay-for-the-study-of-drugs-acting-on-ligand-gated-ion-channels
#14
A Menegon, S Pitassi, N Mazzocchi, L Redaelli, R Rizzetto, J F Rolland, C Poli, M Imberti, A Lanati, F Grohovaz
Ligand gated ion channels are involved in many pathophysiological processes and represent a relevant, although challenging, target for drug discovery. We propose an innovative electro-optical approach to their analysis able to derive membrane conductance values from the local membrane potential changes imposed by test current pulses and measured by fast voltage-sensitive fluorescent dyes. We exploited the potential of this proprietary method by developing a drug testing system called "ionChannel Optical High-content Microscope" (ionChannelΩ)...
March 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28320963/conformational-dynamics-and-role-of-the-acidic-pocket-in-asic-ph-dependent-gating
#15
Sabrina Vullo, Gaetano Bonifacio, Sophie Roy, Niklaus Johner, Simon Bernèche, Stephan Kellenberger
Acid-sensing ion channels (ASICs) are proton-activated Na(+) channels expressed in the nervous system, where they are involved in learning, fear behaviors, neurodegeneration, and pain sensation. In this work, we study the role in pH sensing of two regions of the ectodomain enriched in acidic residues: the acidic pocket, which faces the outside of the protein and is the binding site of several animal toxins, and the palm, a central channel domain. Using voltage clamp fluorometry, we find that the acidic pocket undergoes conformational changes during both activation and desensitization...
March 20, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28320373/nelumbo-nucifera-leaves-extracts-inhibit-mouse-airway-smooth-muscle-contraction
#16
Xiao Yang, Lu Xue, Qingyang Zhao, Congli Cai, Qing-Hua Liu, Jinhua Shen
BACKGROUND: Alkaloids extracted from lotus leaves (AELL) can relax vascular smooth muscle. However, whether AELL has a similar relaxant role on airway smooth muscle (ASM) remains unknown. This study aimed to explore the relaxant property of AELL on ASM and the underlying mechanism. METHODS: Alkaloids were extracted from dried lotus leaves using the high temperature rotary evaporation extraction method. The effects of AELL on mouse ASM tension were studied using force measuring and patch-clamp techniques...
March 20, 2017: BMC Complementary and Alternative Medicine
https://www.readbyqxmd.com/read/28319196/h-channels-in-embryonic-biomphalaria-glabrata-cell-membranes-putative-roles-in-snail-host-schistosome-interactions
#17
Brandon J Wright, Utibe Bickham-Wright, Timothy P Yoshino, Meyer B Jackson
The human blood fluke Schistosoma mansoni causes intestinal schistosomiasis, a widespread neglected tropical disease. Infection of freshwater snails Biomphalaria spp. is an essential step in the transmission of S. mansoni to humans, although the physiological interactions between the parasite and its obligate snail host that determine success or failure are still poorly understood. In the present study, the B. glabrata embryonic (Bge) cell line, a widely used in vitro model for hemocyte-like activity, was used to investigate membrane properties, and assess the impact of larval transformation proteins (LTP) on identified ion channels...
March 20, 2017: PLoS Neglected Tropical Diseases
https://www.readbyqxmd.com/read/28319030/ischemic-small-intestine-in-vivo-versus-ex-vivo-bioimpedance-measurements
#18
Runar James Strand-Amundsen, Henrik Reims, Christian Tronstad, Havard Kalvoy, Orjan Martinsen, Jan Hogetveit, Tom Erik Ruud, Tor Inge Tønnessen
Bioimpedance has been used to investigate changes in electrical parameters during ischemia in various tissues. The small intestine is a multi-layered structure, with several distinct tissue types, and ischemia related changes occur at different times in the different intestinal layers. When investigating how the electrical properties in the small intestine is affected by ischemia, some researchers have used ex-vivo models while others have used in-vivo models. In this study, we compare ischemic time development of electrical parameters in ischemic in-vivo versus ex-vivo small intestine...
March 20, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28315292/hypoxic-culture-promotes-dopaminergic-neuronal-differentiation-of-nasal-olfactory-mucosa-mesenchymal-stem-cells-via-up-regulation-of-hypoxia-inducible-factor-1%C3%AE
#19
Yi Zhuo, Lei Wang, Lite Ge, Xuan Li, Ping Chen, Da Duan, Xiaohua Teng, Miao Jiang, Kai Liu, Ting Yuan, Pei Wu, Hao Wang, Yujia Deng, Huali Xie, Ying Xia, Ming Lu
<p><b>Background</b> Olfactory mucosa mesenchymal stem cells (OM-MSCs) display significant clonogenicactivity and may be easily propagated for Parkinson's disease therapies. Methods of inducing OM-MSCs to differentiate into dopaminergic (DAergic) neurons using olfactory ensheathing cells (OECs) is thus an attractive topic of research.</p><p><b>Methods</b> We designed a hypoxic-induction protocol to generate DAergic neurons from OM-MSCs using a physiological oxygen (O2) level of 3% and OEC-conditioned medium (HI group)...
March 17, 2017: Cell Transplantation
https://www.readbyqxmd.com/read/28314951/relaxin-3-rxfp3-signalling-in-mouse-hypothalamus-no-effect-of-rxfp3-activation-on-corticosterone-despite-reduced-presynaptic-excitatory-input-onto-paraventricular-crh-neurons-in-vitro
#20
C Zhang, D V Baimoukhametova, C M Smith, J S Bains, Andrew L Gundlach
Relaxin-3/RXFP3 signalling is proposed to be involved in the neuromodulatory control of arousal- and stress-related neural circuits. Furthermore, previous studies in rats have led to the proposal that relaxin-3/RXFP3 signalling is associated with activation of the hypothalamic-pituitary-adrenal axis, but direct evidence for RXFP3-related actions on the activity of hypothalamic corticotropin-releasing hormone (CRH) neurons is lacking. In this study, we investigated characteristics of the relaxin-3/RXFP3 system in mouse hypothalamus...
March 17, 2017: Psychopharmacology
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