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https://www.readbyqxmd.com/read/28440808/automated-and-manual-patch-clamp-data-of-human-induced-pluripotent-stem-cell-derived-dopaminergic-neurons
#1
Denise Franz, Hervør Lykke Olsen, Oliver Klink, Jan Gimsa
Human induced pluripotent stem cells can be differentiated into dopaminergic neurons (Dopa.4U). Dopa.4U neurons expressed voltage-gated NaV and KV channels and showed neuron-like spontaneous electrical activity. In automated patch clamp measurements with suspended Dopa.4U neurons, delayed rectifier K(+) current (delayed KV) and rapidly inactivating A-type K(+) current (fast KV) were identified. Examination of the fast KV current with inhibitors yielded IC50 values of 0.4 mM (4-aminopyridine) and 0.1 mM (tetraethylammonium)...
April 25, 2017: Scientific Data
https://www.readbyqxmd.com/read/28436171/sex-and-regional-differences-in-rabbit-right-ventricular-l-type-calcium-current-levels-and-mathematical-modeling-of-arrhythmia-vulnerability
#2
Zane M Kalik, Joshua L Mike, Cassandra Slipski, Moriah Wright, Jozsi Z Jalics, Mark D Womble
Previous studies have shown that adult rabbit left ventricular myocytes exhibit sex and regional differences in L-type calcium current (ICa-L ) levels that contribute to increased susceptibility to arrhythmogenic early afterdepolarizations (EADs). We used patch clamp recordings from isolated adult male and female rabbit right ventricular myocytes to determine apex-base differences in ICa-L density, and mathematical modeling to examine ICa-L contribution to EAD formation. Current density measured at 0 mV in female base myocytes was 67% higher than male base myocytes and 55% higher than female apex myocytes...
April 24, 2017: Experimental Physiology
https://www.readbyqxmd.com/read/28430892/anti-arrhythmic-potential-of-the-late-sodium-current-inhibitor-gs-458967-in-murine-scn5a-1798insd-and-human-scn5a-1795insd-ipsc-derived-cardiomyocytes
#3
Vincent Portero, Simona Casini, Maaike Hoekstra, Arie O Verkerk, Isabella Mengarelli, Luiz Belardinelli, Sridharan Rajamani, Arthur A M Wilde, Connie R Bezzina, Marieke W Veldkamp, Carol Ann Remme
AIM: Selective inhibition of cardiac late sodium current (INaL) is an emerging target in the treatment of ventricular arrhythmias. We investigated the electrophysiological effects of GS-458967 (GS967), a potent, selective inhibitor of INaL, in an overlap syndrome model of both gain and loss of sodium channel function, comprising cardiomyocytes derived from both human SCN5A-1795insD+/- induced pluripotent stem cells (hiPSC-CMs) and mice carrying the homologous mutation Scn5a-1798insD+/-...
April 18, 2017: Cardiovascular Research
https://www.readbyqxmd.com/read/28429218/modification-of-calcium-activated-chloride-currents-in-cerebellar-purkinje-neurons
#4
E A Vikhareva, V L Zamoyski, V V Grigoriev
The whole-cell voltage clamp technique was employed to record the total ionic currents in rat cerebellar Purkinje neurons. When intrapipette solution contained 120 mM KCl, replacement of the standard external physiological saline with Na-free solution resulted in appearance of inward tail current after the end of the depolarizing pulse. When intrapipette potassium ions were replaced for cesium ones, the tail currents were observed even in the presence of normal Na(+) concentration (140 mM) in the external solution...
April 21, 2017: Bulletin of Experimental Biology and Medicine
https://www.readbyqxmd.com/read/28428758/modulation-of-asymmetric-flux-in-heterotypic-gap-junctions-by-pore-shape-particle-size-and-charge
#5
Abhijit Mondal, Frank B Sachse, Alonso P Moreno
Gap junction channels play a vital role in intercellular communication by connecting cytoplasm of adjoined cells through arrays of channel-pores formed at the common membrane junction. Their structure and properties vary depending on the connexin isoform(s) involved in forming the full gap junction channel. Lack of information on the molecular structure of gap junction channels has limited the development of computational tools for single channel studies. Currently, we rely on cumbersome experimental techniques that have limited capabilities...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/28428226/rapid-throughput-analysis-of-gabaa-receptor-subtype-modulators-and-blockers-using-disbac1-3-membrane-potential-red-dye
#6
Atefeh Mousavi Nik, Brandon Pressly, Vikrant Singh, Shane Antrobus, Susan Hulsizer, Michael A Rogawski, Heike Wulff, Isaac N Pessah
Fluorometric Imaging Plate Reader (FLIPR®) membrane potential dye (FMP-Red-Dye) is a proprietary tool for basic discovery and high throughput drug screening for G-protein coupled receptors and ion channels. We optimized and validated this potentiometric probe to assay functional modulators of heterologous expressed GABAA receptor (GABAAR) isoforms (synaptic α1β3γ2, extrasynaptic α4β3δ, and β3 homopentomers). High-resolution mass spectrometry identified FMP-Red-dye as DisSBAC1(3). GABAAR expressing cells equilibrated with FMP-Red-Dye exhibited depolarized equilibrium membrane (Em) potentials compared to GABAAR-null cells...
April 20, 2017: Molecular Pharmacology
https://www.readbyqxmd.com/read/28423317/loss-of-nav%C3%AE-4-mediated-regulation-of-sodium-currents-in-adult-purkinje-neurons-disrupts-firing-and-impairs-motor-coordination-and-balance
#7
Joseph L Ransdell, Edward Dranoff, Brandon Lau, Wan-Lin Lo, David L Donermeyer, Paul M Allen, Jeanne M Nerbonne
The resurgent component of voltage-gated Na(+) (Nav) currents, INaR, has been suggested to provide the depolarizing drive for high-frequency firing and to be generated by voltage-dependent Nav channel block (at depolarized potentials) and unblock (at hyperpolarized potentials) by the accessory Navβ4 subunit. To test these hypotheses, we examined the effects of the targeted deletion of Scn4b (Navβ4) on INaR and on repetitive firing in cerebellar Purkinje neurons. We show here that Scn4b(-/-) animals have deficits in motor coordination and balance and that firing rates in Scn4b(-/-) Purkinje neurons are markedly attenuated...
April 18, 2017: Cell Reports
https://www.readbyqxmd.com/read/28423316/diversity-in-excitation-inhibition-mismatch-underlies-local-functional-heterogeneity-in-the-rat-auditory-cortex
#8
Can Tao, Guangwei Zhang, Chang Zhou, Lijuan Wang, Sumei Yan, Huizhong Whit Tao, Li I Zhang, Yi Zhou, Ying Xiong
Cortical neurons are heterogeneous in their functional properties. This heterogeneity is fundamental for the processing of different features of sensory information. However, functional diversity within a local group of neurons is poorly understood. Here, we demonstrate that neighboring cortical neurons in layer 5 but not those of layer 4 of the rat anterior auditory field (AAF) exhibited a surprisingly high level of diversity in tonal receptive fields. In vivo whole-cell voltage-clamp recordings revealed that the diversity of frequency representation was due to a spectral mismatch between synaptic excitation and inhibition to varying degrees...
April 18, 2017: Cell Reports
https://www.readbyqxmd.com/read/28422818/inhibition-of-metabotropic-glutamate-receptor-subtype-1-alters-the-excitability-of-the-commissural-pyramidal-neuron-in-the-rat-anterior-cingulate-cortex-after-chronic-constriction-injury-to-the-sciatic-nerve
#9
Shi-Hao Gao, Lin-Lin Shen, Hui-Zhong Wen, Yan-Dong Zhao, Huai-Zhen Ruan
BACKGROUND: Inhibition of the metabotropic glutamate receptor subtype 1 in the anterior cingulate cortex has an analgesic effect during sustained nociceptive hypersensitivity. However, the specific changes in different subtypes of anterior cingulate cortex layer 5 pyramidal neurons, as well as the distinct effect of metabotropic glutamate receptor subtype 1 inhibition on different neuronal subtypes, have not been well studied. METHODS: Retrograde labeling combined with immunofluorescence, whole cell clamp recording, and behavioral tests combined with RNA interference were performed in a rat model of chronic constriction injury to the sciatic nerve...
April 19, 2017: Anesthesiology
https://www.readbyqxmd.com/read/28419410/selective-and-state-dependent-activation-of-tresk-background-potassium-channel-by-cloxyquin
#10
Miklós Lengyel, Alice Dobolyi, Gábor Czirják, Péter Enyedi
BACKGROUND AND PURPOSE: Cloxyquin (5-cloroquinolin-8-ol) has been previously described as an activator of TRESK (K2P 18.1, TWIK-related spinal cord K(+) channel) background potassium channel. We have examined the specificity of the drug by testing several K2P channels. We have investigated the mechanism of cloxyquin-mediated TRESK activation, focusing on the differences between the physiologically relevant regulatory states of the channel. EXPERIMENTAL APPROACH: Potassium currents were measured by two-electrode voltage clamp in Xenopus oocytes and by whole-cell patch clamp in mouse dorsal root ganglion (DRG) neurons...
April 18, 2017: British Journal of Pharmacology
https://www.readbyqxmd.com/read/28418242/slow-but-steady-wins-the-race-dissimilarities-among-new-dual-inhibitors-of-the-wild-type-and-the-v27a-mutant-m2-channels-of-influenza-a-virus
#11
Marta Barniol-Xicota, Sabrina Gazzarrini, Eva Torres, Yanmei Hu, Jun Wang, Lieve Naesens, Anna Moroni, Santiago Vázquez
New insights on the amantadine resistance mechanism of the V27A mutant were obtained through the study of novel, easily accessible 4-(1- and 2-adamantyl)piperidines, identified as dual binders of the wild-type and V27A mutant M2 channels of influenza A virus. Their antiviral activity and channel blocking ability were determined using cell-based assays and two-electrode voltage clamp (TEVC) technique on M2 channels, respectively. In addition, electrophysiology experiments revealed two interesting findings: (i) these inhibitors display a different behavior against the wild-type versus V27A mutant A/M2 channels, and (ii) the compounds display antiviral activity when they have kd equal or smaller than 10(-6) while they do not exhibit antiviral activity when kd is 10(-5) or higher although they may show blocking activity in the TEV assay...
April 24, 2017: Journal of Medicinal Chemistry
https://www.readbyqxmd.com/read/28416372/effects-of-bilobalide-ginkgolide-b-and-picrotoxinin-on-gabaa-receptor-modulation-by-structurally-diverse-positive-modulators
#12
Chiu Chin Ng, Rujee K Duke, Tina Hinton, Graham A R Johnston
Anxiolytics and anticonvulsants generally positively modulate the action of GABA, whereas many convulsants (including the chloride channel blocker picrotoxinin) negatively modulate the action of GABA on GABAA receptors. Like picrotoxinin, bilobalide and ginkgolide B, active constituents of Ginkgo biloba, have been shown to negatively modulate the action of GABA at α1β2γ2L GABAA receptors. However, unlike picrotoxinin, bilobalide and ginkgolide B are not known to cause convulsions. We have assessed the action of bilobalide, ginkgolide B and picrotoxinin on a range of GABAA modulators (etomidate, loreclezole, propofol, thiopentone sodium, diazepam, and allopregnanolone), using two-electrode voltage clamp electrophysiology at recombinant α1β2γ2L GABAA receptors expressed in Xenopus oocytes...
April 14, 2017: European Journal of Pharmacology
https://www.readbyqxmd.com/read/28411375/development-of-tetramethylenedisulfotetramine-tets-hapten-library-synthesis-electrophysiological-studies-and-immune-response-in-rabbits
#13
Bogdan Barnych, Natalia Vasylieva, Tom Joseph, Susan Hulsizer, Hai Nguyen, Tomas Cajka, Isaac Pessah, Heike Wulff, Shirley Gee, Bruce Hammock
There is a need for fast detection methods for the banned rodenticide tetramethylenedisulfotetramine (TETS), a highly potent blocker of the γ-aminobutyric acid (GABAA) receptors. General synthetic approach toward two groups of analogues was developed. Screening of the resulting library of compounds by FLIPR or whole-cell voltage-clamp revealed that despite the structural differences some of the TETS analogues retained GABAA receptor inhibition, however their potency was an order of magnitude lower. Antibodies raised in rabbits against some of the TETS analogues conjugated to protein recognized free TETS and will be used for the development of an immunoassay for TETS...
April 14, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28404730/not-flying-blind-a-comparative-study-of-photoreceptor-function-in-flying-and-non-flying-cockroaches
#14
Roman V Frolov, Atsuko Matsushita, Kentaro Arikawa
Flying is often associated with superior visual performance since good vision is crucial for detection and implementation of rapid visually-guided aerial movements. To understand the evolution of insect visual systems it is therefore important to compare phylogenetically related species with different investments into flight capability. Here, we describe and compare morphological and electrophysiological properties of photoreceptors from the habitually flying green cockroach Panchlora nivea, and the American cockroach Periplaneta americana, which flies only at high ambient temperatures...
April 12, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28395994/thujone-inhibits-the-function-of-%C3%AE-7-nicotinic-acetylcholine-receptors-and-impairs-nicotine-induced-memory-enhancement-in-one-trial-passive-avoidance-paradigm
#15
Ahmed Sultan, Keun-Hang Susan Yang, Dmitro Isaev, Eslam El Nebrisi, Nurulain Syed, Nadia Khan, Christopher F Howarth, Bassem Sadek, Murat Oz
Effects of thujone, a major ingredient of absinthe, wormwood oil and some herbal medicines, were tested on the function of α7 subunit of the human nicotinic acetylcholine (α7 nACh) receptor expressed in Xenopus oocytes using the two-electrode voltage-clamp technique. Thujone reversibly inhibited ACh (100μM)-induced currents with an IC50 value of 24.7μM. The effect of thujone was not dependent on the membrane potential and did not involve Ca(2+)-dependent Cl(-) channels expressed endogenously in oocytes...
April 7, 2017: Toxicology
https://www.readbyqxmd.com/read/28394849/inhibition-of-voltage-gated-na-channels-by-bupivacaine-is-enhanced-by-the-adjuvants-buprenorphine-ketamine-and-clonidine
#16
Carsten Stoetzer, Christine Martell, Jeanne de la Roche, Andreas Leffler
BACKGROUND AND OBJECTIVES: Regional anesthesia includes application of local anesthetics (LAs) into the vicinity of peripheral nerves. Prolongation or improvement of nerve blocks with LAs can be accomplished by coapplication with adjuvants, including buprenorphine, ketamine, and clonidine. While the mechanisms mediating prolonged or improved LA-induced effects by adjuvants are poorly understood, we hypothesized that they are likely to increase LA-induced block of voltage-gated Na channels...
April 7, 2017: Regional Anesthesia and Pain Medicine
https://www.readbyqxmd.com/read/28387457/dampened-activity-of-ryanodine-receptor-channels-in-mutant-skeletal-muscle-lacking-tric-a
#17
Sam El-Ajouz, Elisa Venturi, Katja Witschas, Matthew Beech, Abigail D Wilson, Chris Lindsay, David Eberhardt, Fiona O'Brien, Tsunaki Iida, Miyuki Nishi, Hiroshi Takeshima, Rebecca Sitsapesan
TRIC-A is a major component of the nuclear and sarcoplasmic reticulum (SR) membranes of cardiac and skeletal muscle, and is localised closely with RyR channels in the SR terminal cisternae. The skeletal muscle of Tric-a KO mice is characterised by Ca(2+) overloaded and swollen SR and by changes in the properties of SR Ca(2+) release. We therefore investigated if RyR1 gating behaviour is modified in the SR from Tric-a KO mice by incorporating native RyR1 into planar phospholipid bilayers under voltage-clamp conditions...
April 7, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28383569/gating-mechanisms-underlying-deactivation-slowing-by-two-kcnq1-atrial-fibrillation-mutations
#18
Gary Peng, Rene Barro-Soria, Kevin J Sampson, H Peter Larsson, Robert S Kass
KCNQ1 is a voltage-gated potassium channel that is modulated by the beta-subunit KCNE1 to generate IKs, the slow delayed rectifier current, which plays a critical role in repolarizing the cardiac action potential. Two KCNQ1 gain-of-function mutations that cause a genetic form of atrial fibrillation, S140G and V141M, drastically slow IKs deactivation. However, the underlying gating alterations remain unknown. Voltage clamp fluorometry (VCF) allows simultaneous measurement of voltage sensor movement and current through the channel pore...
April 6, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28381558/gain-of-function-mutation-of-a-voltage-gated-sodium-channel-nav1-7-associated-with-peripheral-pain-and-impaired-limb-development
#19
Brian S Tanaka, Phuong T Nguyen, Eray Yihui Zhou, Yong Yang, Vladimir Yarov-Yarovoy, Sulayman D Dib-Hajj, Stephen G Waxman
Dominant mutations in voltage-gated sodium channel NaV1.7 cause inherited erythromelalgia (IEM), a debilitating pain disorder characterized by severe burning pain and redness of the distal extremities. NaV1.7 is preferentially expressed within peripheral sensory and sympathetic neurons. Here, we describe a novel NaV1.7 mutation in an 11-year old male with under-development of the limbs, recurrent attacks of burning pain with erythema and swelling in his feet and hands. Frequency and duration of the episodes gradually increased with age and relief by cooling became less effective...
April 5, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28379373/genetic-and-phenotypic-heterogeneity-suggest-therapeutic-implications-in-scn2a-related-disorders
#20
Markus Wolff, Katrine M Johannesen, Ulrike B S Hedrich, Silvia Masnada, Guido Rubboli, Elena Gardella, Gaetan Lesca, Dorothée Ville, Mathieu Milh, Laurent Villard, Alexandra Afenjar, Sandra Chantot-Bastaraud, Cyril Mignot, Caroline Lardennois, Caroline Nava, Niklas Schwarz, Marion Gérard, Laurence Perrin, Diane Doummar, Stéphane Auvin, Maria J Miranda, Maja Hempel, Eva Brilstra, Nine Knoers, Nienke Verbeek, Marjan van Kempen, Kees P Braun, Grazia Mancini, Saskia Biskup, Konstanze Hörtnagel, Miriam Döcker, Thomas Bast, Tobias Loddenkemper, Lily Wong-Kisiel, Friedrich M Baumeister, Walid Fazeli, Pasquale Striano, Robertino Dilena, Elena Fontana, Federico Zara, Gerhard Kurlemann, Joerg Klepper, Jess G Thoene, Daniel H Arndt, Nicolas Deconinck, Thomas Schmitt-Mechelke, Oliver Maier, Hiltrud Muhle, Beverly Wical, Claudio Finetti, Reinhard Brückner, Joachim Pietz, Günther Golla, Dinesh Jillella, Karen M Linnet, Perrine Charles, Ute Moog, Eve Õiglane-Shlik, John F Mantovani, Kristen Park, Marie Deprez, Damien Lederer, Sandrine Mary, Emmanuel Scalais, Laila Selim, Rudy Van Coster, Lieven Lagae, Marina Nikanorova, Helle Hjalgrim, G Christoph Korenke, Marina Trivisano, Nicola Specchio, Berten Ceulemans, Thomas Dorn, Katherine L Helbig, Katia Hardies, Hannah Stamberger, Peter de Jonghe, Sarah Weckhuysen, Johannes R Lemke, Ingeborg Krägeloh-Mann, Ingo Helbig, Gerhard Kluger, Holger Lerche, Rikke S Møller
Mutations in SCN2A, a gene encoding the voltage-gated sodium channel Nav1.2, have been associated with a spectrum of epilepsies and neurodevelopmental disorders. Here, we report the phenotypes of 71 patients and review 130 previously reported patients. We found that (i) encephalopathies with infantile/childhood onset epilepsies (≥3 months of age) occur almost as often as those with an early infantile onset (<3 months), and are thus more frequent than previously reported; (ii) distinct phenotypes can be seen within the late onset group, including myoclonic-atonic epilepsy (two patients), Lennox-Gastaut not emerging from West syndrome (two patients), and focal epilepsies with an electrical status epilepticus during slow sleep-like EEG pattern (six patients); and (iii) West syndrome constitutes a common phenotype with a major recurring mutation (p...
March 4, 2017: Brain: a Journal of Neurology
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