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Voltage clamp

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https://www.readbyqxmd.com/read/28516122/two-electrode-voltage-clamp-recordings-in-xenopus-laevis-oocytes-reconstitution-of-abscisic-acid-activation-of-slac1-anion-channel-via-pyl9-aba-receptor
#1
Cun Wang, Jingbo Zhang, Julian I Schroeder
Two-Electrode Voltage-Clamp (TEVC) recording in Xenopus laevis oocytes provides a powerful method to investigate the functions and regulation of ion channel proteins. This approach provides a well-known tool to characterize ion channels or transporters expressed in Xenopus laevis oocytes. The plasma membrane of the oocyte is impaled by two microelectrodes, one for voltage sensing and the other one for current injection. Here we list a protocol that allows robust reconstitution of multi-component signaling pathways...
January 20, 2017: Bio-protocol
https://www.readbyqxmd.com/read/28515089/the-n-terminus-regulates-voltage-dependent-gating-of-calhm-ion-channels
#2
Jessica E Tanis, Zhongming Ma, J Kevin Foskett
CALHM1 and its C. elegans (ce) homolog, CLHM-1, belong to a new family of physiologically important ion channels that are regulated by voltage and extracellular Ca(2+) (Ca(2+)o), but lack a canonical voltage-sensing domain. Consequently, the intrinsic voltage-dependent gating mechanisms for CALHM channels are unknown. Here, we performed voltage-clamp experiments on ceCLHM-1 chimeric, deletion, insertion and point mutants to assess the role of the N-terminus (NT) in CALHM channel gating. Analyses of chimeric channels in which the ceCLHM-1 and human (h)CALHM1 N-termini were interchanged showed that the hCALHM1 NT destabilized channel-closed states, whereas the ceCLHM-1 NT had a stabilizing effect...
May 17, 2017: American Journal of Physiology. Cell Physiology
https://www.readbyqxmd.com/read/28514141/subtype-specific-agonists-for-nmda-receptor-glycine-binding-sites
#3
Alex Maolanon, Rune Risgaard, Shuang-Yan Wang, Yoran Snoep, Athanasios Papangelis, Feng Yi, David Holley, Anne F Barslund, Niels Svenstrup, Kasper B Hansen, Rasmus Prætorius Clausen
A series of analogues based on serine as lead structure were designed and their agonist activities were evaluated at recombinant NMDA receptor subtypes (GluN1/2A-D) using two-electrode voltage-clamp (TEVC) electrophysiology. Pronounced variation in subunit-selectivity, potency, and agonist efficacy was observed in a manner that was dependent on the GluN2 subunit in the NMDA receptor. In particular, compounds 15a and 16a are potent GluN2C-specific superagonists at the GluN1 subunit with agonist efficacies of 398% and 308% compared to glycine...
May 17, 2017: ACS Chemical Neuroscience
https://www.readbyqxmd.com/read/28514017/isopimaric-acid-a-multi-targeting-ion-channel-modulator-reducing-excitability-and-arrhythmicity-in-a-spontaneously-beating-mouse-atrial-cell-line
#4
Sajjad Salari, Malin Silverå Ejneby, Johan Brask, Fredrik Elinder
AIM: Atrial fibrillation is the most common persistent cardiac arrhythmia, and it is not well controlled by present drugs. Because some resin acids open voltage-gated potassium channels and reduce neuronal excitability, we explored the effects of the resin acid isopimaric acid (IPA) on action potentials and ion currents in cardiomyocytes. METHODS: Spontaneously beating mouse atrial HL-1 cells were investigated with the whole-cell patch-clamp technique. RESULTS: 1-25 μmol L(-1) IPA reduced the action potential frequency by up to 50%...
May 17, 2017: Acta Physiologica
https://www.readbyqxmd.com/read/28513836/facilitation-of-mossy-fibre-driven-spiking-in-the-cerebellar-nuclei-by-the-synchrony-of-inhibition
#5
Yeechan Wu, Indira M Raman
Large projection neurons of the cerebellar nuclei (CbN cells), whose activity generates movement, are inhibited by Purkinje cells and excited by mossy fibres. The high convergence, firing rates, and strength of Purkinje inputs predict powerful suppression of CbN cell spiking, raising the question of what activity patterns favor excitation over inhibition. Recording from CbN cells at near-physiological temperatures in cerebellar slices from weanling mice, we measured the amplitude, kinetics, voltage-dependence, and short-term plasticity of mossy fibre-mediated EPSCs...
May 17, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28511915/altered-ionic-currents-and-amelioration-by-igf-1-and-pacap-in-motoneuron-derived-cells-modelling-sbma
#6
Aura M Jiménez Garduño, Leon J Juárez-Hernández, María J Polanco, Laura Tosatto, Daniela Michelatti, Daniele Arosio, Manuela Basso, Maria Pennuto, Carlo Musio
Spinal and bulbar muscular atrophy (SBMA), also known as Kennedy's disease, is a motor neuron disease caused by the expansion of a polymorphic CAG tandem repeat encoding a polyglutamine (polyQ) tract in the androgen receptor (AR) gene. SBMA is triggered by the binding of mutant AR to its natural ligands, testosterone and dihydrotestosterone (DHT). To investigate the neuronal alterations of motor neuron cell models of SBMA, we applied patch-clamp methods to verify how polyQ expansions in the AR alter cell ionic currents...
May 10, 2017: Biophysical Chemistry
https://www.readbyqxmd.com/read/28508747/voltage-gated-na-currents-in-human-dorsal-root-ganglion-neurons
#7
Xiulin Zhang, Birgit T Priest, Inna Belfer, Michael S Gold
Available evidence indicates voltage-gated Na(+) channels (VGSCs) in peripheral sensory neurons are essential for the pain and hypersensitivity associated with tissue injury. However, our understanding of the biophysical and pharmacological properties of the channels in sensory neurons is largely based on the study of heterologous systems or rodent tissue, despite evidence that both expression systems and species differences influence these properties. Therefore, we sought to determine the extent to which the biophysical and pharmacological properties of VGSCs were comparable in rat and human sensory neurons...
May 16, 2017: ELife
https://www.readbyqxmd.com/read/28506097/a-computational-model-of-the-ca-2-transients-and-influence-of-buffering-in-guinea-pig-urinary-bladder-smooth-muscle-cells
#8
Vijay Dave, Rohit Manchanda
Many cellular events including electrical activity and muscle contraction are regulated and coordinated by intracellular [Formula: see text] concentration ([[Formula: see text]][Formula: see text]. In detrusor smooth muscle (DSM) cells, [[Formula: see text]]i is normally maintained at very low levels and rises transiently during signalling processes as a result of (i) influx from the extracellular space (mainly via L-type and T-type [Formula: see text] channels) and (ii) [Formula: see text] release from sarcoplasmic reticulum (SR) into the cytoplasm...
April 20, 2017: Journal of Bioinformatics and Computational Biology
https://www.readbyqxmd.com/read/28499969/corticotropin-releasing-hormone-modulates-airway-vagal-preganglionic-neurons-of-sprague-dawley-rats-at-multiple-synaptic-sites-via-activation-of-its-type-1-receptors-implications-for-stress-associated-airway-vagal-excitation
#9
Yuhong Guo, Xianxia Yan, Xingxin Chen, Ding He, Ming Zeng, Yonghua Chen, Chunmei Xia, Dongying Qiu, Jijiang Wang
Corticotropin-releasing hormone release is the final common pathway of stress-associated neuroendocrine responses. This study tested how corticotropin-releasing hormone modulates airway vagal preganglionic neurons. Airway vagal preganglionic neurons in neonatal rats were retrogradely labeled with fluorescent dye and identified in medullary slices, and their responses to corticotropin-releasing hormone (200nmolL(-1)) were examined using whole-cell patch clamp. The results show that under current clamp, corticotropin-releasing hormone (200nmolL(-1)) depolarized airway vagal preganglionic neurons and significantly increased the rate of their spontaneous firing...
May 10, 2017: Neuroscience
https://www.readbyqxmd.com/read/28498898/spatial-asymmetry-and-short-term-suppression-underlie-direction-selectivity-of-synaptic-excitation-in-the-mouse-visual-cortex
#10
Ya-Tang Li, Qi Fang, Li I Zhang, Huizhong Whit Tao
Direction selectivity (DS) of neuronal responses is fundamental for motion detection. With in vivo whole-cell voltage-clamp recordings from layer (L)4 neurons in the mouse visual cortex, we observed a strong correlation between DS and spatial asymmetry in the distribution of excitatory input strengths. This raises an interesting possibility that the latter may contribute to DS. The preferred direction of excitatory input was found from the stronger to weaker side of its spatial receptive field. A simple linear summation of asymmetrically distributed excitatory responses to stationary flash stimuli however failed to predict the correct directionality: it at best resulted in weak DS with preferred direction opposite to what was observed experimentally...
May 11, 2017: Cerebral Cortex
https://www.readbyqxmd.com/read/28495885/proteolytic-cleavage-of-the-hydrophobic-domain-in-the-cav%C3%AE-2%C3%AE-1-subunit-improves-assembly-and-activity-of-cardiac-cav1-2-channels
#11
Emilie Segura, Benoîte Bourdin, Marie-Philippe Tétreault, Julie Briot, Bruce G Allen, Gaétan Mayer, Lucie Parent
Voltage-gated L-type CaV1.2 channels in cardiomyocytes exist as heteromeric complexes with the pore-forming CaVα1, CaVβ, and CaVα2δ1 subunits. The full complement of subunits is required to reconstitute the native-like properties of L-type Ca(2+) currents but the molecular determinants responsible for the formation of the heteromeric complex are still being studied. Enzymatic treatment with PI-PLC, a phospholipase C specific for the cleavage of glycosyl-phosphatidylinositol (GPI)-anchored proteins, disrupted plasma membrane localization of the cardiac CaVα2δ1 prompting us to investigate deletions of its hydrophobic transmembrane domain...
May 11, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28489932/camkii%C3%AE-may-modulate-fentanyl-induced-hyperalgesia-via-a-celc-pag-rvm-spinal-cord-descending-facilitative-pain-pathway-in-rats
#12
Zhen Li, Pingping Yin, Jian Chen, Shenglan Jin, Jieqiong Liu, Fang Luo
Each of the lateral capsular division of central nucleus of amygdala(CeLC), periaqueductal gray (PAG), rostral ventromedial medulla(RVM) and spinal cord has been proved to contribute to the development of opioid-induced hyperalgesia(OIH). Especially, Ca2+/calmodulin-dependent protein kinase IIα (CaMKIIα) in CeLC and spinal cord seems to play a key role in OIH modulation. However, the pain pathway through which CaMKIIα modulates OIH is not clear. The pathway from CeLC to spinal cord for this modulation was explored in the present study...
2017: PloS One
https://www.readbyqxmd.com/read/28489663/use-dependent-inhibition-of-glycine-activated-chloride-current-in-rat-neurons-by-%C3%AE-amyloid-peptide-pretreated-with-hexafluoroisopropanol
#13
Elena I Solntseva, Julia V Bukanova
Hexafluoroisopropanol (HFIP) is a nonpolar organic solvent that is often used to prepare β-amyloid peptide (Aβ) samples. In this work, we compare the effects of two different species derived from synthetic Aβ1-42 and prepared without HFIP (Aβ) or using HFIP (Aβ/HFIP) on the glycine-activated chloride current (IGly). The experiments were conducted on the pyramidal neurons isolated from CA3 region of rat hippocampus. Transmembrane currents were recorded using a conventional patch-clamp technique in the whole-cell configuration...
May 5, 2017: Neuroreport
https://www.readbyqxmd.com/read/28488367/chemosensitive-phox2b-expressing-neurons-are-crucial-for-hypercapnic-ventilatory-response-in-the-nucleus-tractus-solitarius
#14
Congrui Fu, Jinyu Xue, Ri Wang, Jinting Chen, Lan Ma, Yixian Liu, Xuejiao Wang, Fang Guo, Yi Zhang, Xiangjian Zhang, Sheng Wang
The nucleus tractus solitarius (NTS) neurons have been thought to function as central respiratory chemoreceptors. However, it remains unknown regarding the common molecular marker defined for these neurons. Here we ask whether paired-like homeobox 2b (Phox2b)-expressing NTS neurons are recruited in hypercapnic ventilatory response (HCVR) and whether these neurons exhibit intrinsic chemosensitivity. HCVR was assessed using whole body plethysmography and neuronal chemosensitivity was examined by patch clamp recordings in brainstem slices or dissociated neurons from Phox2b-EGFP transgenic mice...
May 10, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28483800/xe991-and-linopirdine-are-state-dependent-inhibitors-for-kv7-kcnq-channels-that-favor-activated-single-subunits
#15
Derek L Greene, Seungwoo Kang, Naoto Hoshi
M-channel inhibitors, especially XE991, are increasingly being used in animal experiments. However, insufficient characterization of XE991 at times confounds the interpretation of results when using this compound. Here, we demonstrate that XE991 and linopirdine are state-dependent inhibitors that favor the activated-subunit of neuronal Kv7/KCNQ channels. We performed patch clamp experiments on homomeric Kv7.2 or heteromeric Kv7.2/3 channels expressed in Chinese hamster ovary cells in order to characterize XE991 and linopirdine...
May 8, 2017: Journal of Pharmacology and Experimental Therapeutics
https://www.readbyqxmd.com/read/28477386/persistent-activation-of-%C3%AE-7-nachrs-associated-with-stable-induction-of-different-desensitized-states
#16
Roger L Papke, Clare Stokes, M Imad Damaj, Ganesh A Thakur, Khan Manther, Millet Treinin, Deniz Bagdas, Abhijit R Kulkarni, Nicole A Horenstein
BACKGROUND AND PURPOSE: GAT107 is a positive allosteric modulator and agonist (ago-PAM) of α7 nicotinic acetylcholine receptors that can cause a prolonged period of primed potentiation of acetylcholine responses after drug washout. NS6740 is a silent agonist of α7 that has little or no efficacy for activating the ion channel but induces stable desensitization states, some of which can be converted into channel-active states by PAMs. Although GAT107 and NS6740 appear to stably induce different non-conducting states, interestingly, both agents have been shown to be effective treatment for inflammation and inflammatory pain models...
May 6, 2017: British Journal of Pharmacology
https://www.readbyqxmd.com/read/28477086/effects-of-salvianolic-acid-b-on-l-type-calcium-channels-and-myocardial-contractility-in-isolated-rat-ventricular-myocytes-and-herg-k-channels-expressed-in-hek293-cells
#17
Qiongtao Song, Xue Han, Yuchong Xue, Tao Song, Xi Chu, Xuan Zhang, Yuanyuan Zhang, Ying Zhang, Jianping Zhang, Li Chu
Salvianolic acid B (Sal B), one of the chief water-soluble constituents in Radix Salviae Milthiorrhizae, has often been reported to possess considerable cardiovascular regulatory effects. However, the underlying biochemical and cellular mechanisms of its cardioprotection remain unclear. This study was designed to evaluate the role of Sal B regulation in L-type Ca(2+) channel currents (ICa,L) and cell contractility in rat cardiomyocytes and hERG K(+) channels expressed in HEK293 cells with the patch-clamp and Ca(2+) imaging techniques to clarify its underlying cardioprotective mechanisms...
May 5, 2017: Naunyn-Schmiedeberg's Archives of Pharmacology
https://www.readbyqxmd.com/read/28476922/sarcolemmal-distribution-of-ica-and-incx-and-ca-autoregulation-in-mouse-ventricular-myocytes
#18
Hanne C Gadeberg, Cherrie H T Kong, Simon M Bryant, Andrew F James, Clive H Orchard
The balance of Ca influx and efflux regulates the Ca load of cardiac myocytes, a process known as autoregulation. Previous work has shown that Ca influx, via L-type Ca current (ICa), and efflux, via Na-Ca exchange (NCX), occur predominantly at t-tubules; however the role of t-tubules in autoregulation is unknown. We therefore investigated the sarcolemmal distribution of ICa and INCX, and autoregulation, in mouse ventricular myocytes using whole cell voltage-clamp and simultaneous Ca measurement in intact and detubulated (DT) cells...
May 5, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28475556/high-concentrations-of-tranexamic-acid-inhibit-ionotropic-glutamate-receptors
#19
Irene Lecker, Dian-Shi Wang, Kirusanthy Kaneshwaran, C David Mazer, Beverley A Orser
BACKGROUND: The antifibrinolytic drug tranexamic acid is structurally similar to the amino acid glycine and may cause seizures and myoclonus by acting as a competitive antagonist of glycine receptors. Glycine is an obligatory co-agonist of the N-methyl-D-aspartate (NMDA) subtype of glutamate receptors. Thus, it is plausible that tranexamic acid inhibits NMDA receptors by acting as a competitive antagonist at the glycine binding site. The aim of this study was to determine whether tranexamic acid inhibits NMDA receptors, as well as α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid and kainate subtypes of ionotropic glutamate receptors...
May 5, 2017: Anesthesiology
https://www.readbyqxmd.com/read/28473457/pharmacologic-characterization-of-amg8379-a-potent-and-selective-small-molecule-sulfonamide-antagonist-of-the-voltage-gated-sodium-channel-nav1-7
#20
Thomas J Kornecook, Ruoyuan Yin, Stephen Altmann, Xuhai Be, Virginia Berry, Christopher P Ilch, Michael Jarosh, Danielle Johnson, Josie H Lee, Sonya G Lehto, Joseph Ligutti, Dong Liu, Jason Luther, David Matson, Danny Ortuno, John Roberts, Kristin Taborn, Jinti Wang, Matthew M Weiss, Violeta Yu, Dawn X D Zhu, Robert T Fremeau, Bryan D Moyer
Potent and selective antagonists of the voltage-gated sodium channel NaV1.7 represent a promising avenue for the development of new chronic pain therapies. We generated a small molecule atropisomer quinolone sulfonamide antagonist AMG8379 and a less active enantiomer AMG8380. Here we show that AMG8379 potently blocks human NaV1.7 channels with an IC50 of 8.5 nM and endogenous tetrodotoxin (TTX)-sensitive sodium channels in dorsal root ganglia (DRG) neurons with an IC50 of 3.1 nM in whole cell patch clamp electrophysiology assays using a voltage protocol that interrogates channels in a partially inactivated state...
May 4, 2017: Journal of Pharmacology and Experimental Therapeutics
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