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Voltage clamp

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https://www.readbyqxmd.com/read/27919294/heantos-4-a-natural-plant-extract-used-in-the-treatment-of-drug-addiction-modulates-t-type-calcium-channels-and-thalamocortical-burst-firing
#1
Stuart M Cain, Soyon Ahn, Esperanza Garcia, Yiming Zhang, Zeina Waheed, John R Tyson, Yi Yang, Tran Van Sung, Anthony G Phillips, Terrance P Snutch
Heantos-4 is a refined combination of plant extracts currently approved to treat opiate addiction in Vietnam. In addition to its beneficial effects on withdrawal and prevention of relapse, reports of sedation during clinical treatment suggest that arousal networks in the brain may be recruited during Heantos administration. T-type calcium channels are implicated in the generation of sleep rhythms and in this study we examined whether a Heantos-4 extraction modulates T-type calcium channel currents generated by the Cav3...
December 5, 2016: Molecular Brain
https://www.readbyqxmd.com/read/27917616/effect-of-redox-modifying-agents-on-the-activity-of-channelrhodopsin-2
#2
Bao-Ming Wu, Tian-Dong Leng, Koichi Inoue, Jun Li, Zhi-Gang Xiong
BACKGROUND: The algal protein Channelrhodopsin-2 (ChR2) has been widely used in recent years in optogenetic technique to investigate the functions of complex neuronal networks through minimally invasive and temporally precise photostimulation of genetically defined neurons. However, as with any other new technique, current optogentic approaches have various limitations. In addition, how ChR2 may behave in response to complex biochemical changes associated with various physiological/pathological conditions is largely unknown...
December 4, 2016: CNS Neuroscience & Therapeutics
https://www.readbyqxmd.com/read/27914611/restoration-of-uridine-5-triphosphate-suppressed-delayed-rectifying-k-currents-by-an-no-activator-kmup-1-involves-rhoa-rho-kinase-signaling-in-pulmonary-artery-smooth-muscle-cells
#3
Zen-Kong Dai, Chang-Ling Kao, Su-Ling Hsieh, Ing-Jun Chen, Bin-Nan Wu
We have demonstrated that KMUP-1 (7-[2-[4-(2-chlorobenzene)piperazinyl]ethyl]-1,3-dimethylxanthine) blunts monocrotaline-induced pulmonary arterial hypertension by altering Ca(2+) sensitivity, K(+)-channel function, endothelial nitric oxide synthase activity, and RhoA/Rho kinase (ROCK) expression. This study further investigated whether KMUP-1 impedes uridine 5'-triphosphate (UTP)-inhibited delayed rectifying K(+) (KDR) current in rat pulmonary arteries involved the RhoA/ROCK signaling. Pulmonary artery smooth muscle cells (PASMCs) were enzymatically dissociated from rat pulmonary arteries...
December 2016: Kaohsiung Journal of Medical Sciences
https://www.readbyqxmd.com/read/27911759/neurotransmitter-release-can-be-stabilized-by-a-mechanism-that-prevents-voltage-changes-near-the-end-of-action-potentials-from-affecting-calcium-currents
#4
Stephen G Clarke, Matthew S Scarnati, Kenneth G Paradiso
: At chemical synapses, presynaptic action potentials (APs) activate voltage-gated calcium channels, allowing calcium to enter and trigger neurotransmitter release. The duration, peak amplitude, and shape of the AP falling phase alter calcium entry, which can affect neurotransmitter release significantly. In many neurons, APs do not immediately return to the resting potential, but instead exhibit a period of depolarization or hyperpolarization referred to as an afterpotential. We hypothesized that presynaptic afterpotentials should alter neurotransmitter release by affecting the electrical driving force for calcium entry and calcium channel gating...
November 9, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/27909101/changes-in-properties-of-auditory-nerve-synapses-following-conductive-hearing-loss
#5
Xiaowen Zhuang, Wei Sun, Matthew A Xu-Friedman
: Auditory activity plays an important role in the development of the auditory system. Decreased activity can result from conductive hearing loss (CHL) associated with otitis media, which may lead to long-term perceptual deficits. The effects of CHL have been mainly studied at later stages of the auditory pathway, but early stages remain less examined. However, changes in early stages could be important, because they would affect how information about sounds is conveyed to higher order areas for further processing and localization...
December 1, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/27908040/modeling-and-design-of-two-dimensional-membrane-type-active-acoustic-metamaterials-with-tunable-anisotropic-density
#6
Ahmed Allam, Adel Elsabbagh, Wael Akl
A two-dimensional active acoustic metamaterial with controllable anisotropic density is introduced. The material consists of composite lead-lead zirconate titanate plates clamped to an aluminum structure with air as the background fluid. The effective anisotropic density of the material is controlled, independently for two orthogonal directions, by means of an external static electric voltage signal. The material is used in the construction of a reconfigurable waveguide capable of controlling the direction of the acoustic waves propagating through it...
November 2016: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/27906053/attenuated-ca-2-release-in-a-mouse-model-of-limb-girdle-muscular-dystrophy-2a
#7
Marino DiFranco, Irina Kramerova, Julio L Vergara, Melissa Jan Spencer
BACKGROUND: Mutations in CAPN3 cause limb girdle muscular dystrophy type 2A (LGMD2A), a progressive muscle wasting disease. CAPN3 is a non-lysosomal, Ca-dependent, muscle-specific proteinase. Ablation of CAPN3 (calpain-3 knockout (C3KO) mice) leads to reduced ryanodine receptor (RyR1) expression and abnormal Ca2+/calmodulin-dependent protein kinase II (Ca-CaMKII)-mediated signaling. We previously reported that Ca(2+) release measured by fura2-FF imaging in response to single action potential stimulation was reduced in old C3KO mice; however, the use of field stimulation prevented investigation of the mechanisms underlying this impairment...
February 24, 2016: Skeletal Muscle
https://www.readbyqxmd.com/read/27901080/block-of-nicotinic-acetylcholine-receptors-by-philanthotoxins-is-strongly-dependent-on-their-subunit-composition
#8
Hamid S Kachel, Rohit N Patel, Henrik Franzyk, Ian R Mellor
Philanthotoxin-433 (PhTX-433) is an active component of the venom from the Egyptian digger wasp, Philanthus triangulum. PhTX-433 inhibits several excitatory ligand-gated ion channels, and to improve selectivity two synthetic analogues, PhTX-343 and PhTX-12, were developed. Previous work showed a 22-fold selectivity of PhTX-12 over PhTX-343 for embryonic muscle-type nicotinic acetylcholine receptors (nAChRs) in TE671 cells. We investigated their inhibition of different neuronal nAChR subunit combinations as well as of embryonic muscle receptors expressed in Xenopus oocytes...
November 30, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27898416/sgk3-sensitivity-of-large-conductance-ca2-activated-k-channel
#9
Musaab Ahmed, Myriam Fezai, Florian Lang
BACKGROUND/AIMS: Large conductance Ca2+-activated K+ channels (maxi K+ channels or BK channels) are rapidly activated by increase of cytosolic Ca2+ activity. The channels participate in the regulation of diverse functions including neuronal excitation and cell volume. The BK channels may be modified by kinases. Channel regulating kinases include the serum & glucocorticoid inducible kinase 3 (SGK3). The present study explored whether SGK3 modifies the activity of BK channels. METHODS: cRNA encoding the Ca2+ insensitive BK channel mutant BKM513I+Δ899-903 was injected into Xenopus laevis oocytes without or with additional injection of cRNA encoding wild-type SGK3, constitutively active S419DSGK3, or catalytically inactive K191NSGK3...
November 30, 2016: Neuro-Signals
https://www.readbyqxmd.com/read/27889432/decrease-of-high-voltage-ca-2-currents-in-the-dentate-gyrus-granule-cells-by-entorhinal-amyloidopathy-is-reversed-by-calcium-channel-blockade
#10
Hamid Gholami Pourbadie, Nima Naderi, Hadi Mirzapour Delavar, Mahshid Hosseinzadeh, Nasrin Mehranfard, Fariba Khodagholi, Mahyar Janahmadi, Fereshteh Motamedi
In the Alzheimer's disease (AD), entorhinal-hippocampal circuit is one of the earliest affected networks. There are some evidences indicating abnormal neuronal excitability and impaired synaptic plasticity in the dentate gyrus (DG) of AD animal model. However, the underlying mechanism leading to DG dysfunction particularly in the early phase of AD is not known. Since calcium dyshomeostasis has a critical role in the etiology of AD, it is possible that this phenomenon precedes electrophysiological alteration in the DG...
November 24, 2016: European Journal of Pharmacology
https://www.readbyqxmd.com/read/27888095/modulation-of-voltage-gated-conductances-of-retinal-horizontal-cells-by-uv-excited-tio2-nanoparticles
#11
Xenia Meshik, Min Choi, Adam Baker, R Paul Malchow, Leigha Covnot, Samuel Doan, Souvik Mukherjee, Sidra Farid, Mitra Dutta, Michael A Stroscio
This study examines the ability of optically-excited titanium dioxide nanoparticles to influence voltage-gated ion channels in retinal horizontal cells. Voltage clamp recordings were obtained in the presence and absence of TiO2 and ultraviolet laser excitation. Significant current changes were observed in response to UV light, particularly in the -40 mV to +40 mV region where voltage-gated Na(+) and K(+) channels have the highest conductance. Cells in proximity to UV-excited TiO2 exhibited a left-shift in the current-voltage relation of around 10 mV in the activation of Na(+) currents...
November 22, 2016: Nanomedicine: Nanotechnology, Biology, and Medicine
https://www.readbyqxmd.com/read/27881847/epigenetic-regulation-of-l-type-voltage-gated-ca-2-channels-in-mesenteric-arteries-of-aging-hypertensive-rats
#12
Jingwen Liao, Yanyan Zhang, Fang Ye, Lin Zhang, Yu Chen, Fanxing Zeng, Lijun Shi
Accumulating evidence has shown that epigenetic regulation is involved in hypertension and aging. L-type voltage-gated Ca(2+) channels (LTCCs), the dominant channels in vascular myocytes, greatly contribute to arteriole contraction and blood pressure (BP) control. We investigated the dynamic changes and epigenetic regulation of LTCC in the mesenteric arteries of aging hypertensive rats. LTCC function was evaluated by using microvascular rings and whole-cell patch-clamp in the mesenteric arteries of male Wistar-Kyoto rats and spontaneously hypertensive rats at established hypertension (3 month old) and an aging stage (16 month old), respectively...
November 24, 2016: Hypertension Research: Official Journal of the Japanese Society of Hypertension
https://www.readbyqxmd.com/read/27881784/low-somatic-sodium-conductance-enhances-action-potential-precision-in-time-coding-auditory-neurons
#13
Yang Yang, Bina Ramamurthy, Andreas Neef, Matthew A Xu-Friedman
: Auditory nerve fibers encode sounds in the precise timing of action potentials (APs), which is used for such computations as sound localization. Timing information is relayed through several cell types in the auditory brainstem that share an unusual property: their APs are not overshooting, suggesting that the cells have very low somatic sodium conductance (gNa). However, it is not clear how gNa influences temporal precision. We addressed this by comparing bushy cells (BCs) in the mouse cochlear nucleus with T-stellate cells (SCs), which do have normal overshooting APs...
November 23, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/27877113/the-effects-of-realistic-synaptic-distribution-and-3d-geometry-on-signal-integration-and-extracellular-field-generation-of-hippocampal-pyramidal-cells-and-inhibitory-neurons
#14
Attila I Gulyás, Tamás F Freund, Szabolcs Káli
In vivo and in vitro multichannel field and somatic intracellular recordings are frequently used to study mechanisms of network pattern generation. When interpreting these data, neurons are often implicitly considered as electrotonically compact cylinders with a homogeneous distribution of excitatory and inhibitory inputs. However, the actual distributions of dendritic length, diameter, and the densities of excitatory and inhibitory input are non-uniform and cell type-specific. We first review quantitative data on the dendritic structure and synaptic input and output distribution of pyramidal cells (PCs) and interneurons in the hippocampal CA1 area...
2016: Frontiers in Neural Circuits
https://www.readbyqxmd.com/read/27872281/interactions-of-divalent-cations-with-calcium-binding-sites-of-bk-channels-reveal-independent-motions-within-the-gating-ring
#15
Pablo Miranda, Teresa Giraldez, Miguel Holmgren
Large-conductance voltage- and calcium-activated K(+) (BK) channels are key physiological players in muscle, nerve, and endocrine function by integrating intracellular Ca(2+) and membrane voltage signals. The open probability of BK channels is regulated by the intracellular concentration of divalent cations sensed by a large structure in the BK channel called the "gating ring," which is formed by four tandems of regulator of conductance for K(+) (RCK1 and RCK2) domains. In contrast to Ca(2+) that binds to both RCK domains, Mg(2+), Cd(2+), or Ba(2+) interact preferentially with either one or the other...
November 21, 2016: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/27866274/ryanodine-receptor-type-3-does-not-contribute-to-contractions-in-the-mouse-myometrium-regardless-of-pregnancy
#16
Katsuhito Matsuki, Masashi Takemoto, Yoshiaki Suzuki, Hisao Yamamura, Susumu Ohya, Hiroshi Takeshima, Yuji Imaizumi
Ryanodine receptor type 3 (RyR3) is expressed in myometrial smooth muscle cells (MSMCs). The short isoform of RyR3 is a dominant negative variant (DN-RyR3) and negatively regulates the functions of RyR2 and full-length (FL)-RyR3. DN-RyR3 has been suggested to function as a major RyR3 isoform in non-pregnant (NP) mouse MSMCs, and FL-RyR3 may also be upregulated during pregnancy (P). This increase in the FL-RyR3/DN-RyR3 ratio may contribute to the strong contractions by MSMCs for parturition. In the present study, spontaneous contractions by the myometrium in NP and P mice were highly susceptible to nifedipine but were not affected by ryanodine...
November 20, 2016: Pflügers Archiv: European Journal of Physiology
https://www.readbyqxmd.com/read/27864845/activity-of-the-anticonvulsant-lacosamide-in-experimental-and-human-epilepsy-via-selective-effects-on-slow-na-channel-inactivation
#17
Dominik Holtkamp, Thoralf Opitz, Isabelle Niespodziany, Christian Wolff, Heinz Beck
OBJECTIVE: In human epilepsy, pharmacoresistance to antiepileptic drug therapy is a major problem affecting ~30% of patients with epilepsy. Many classical antiepileptic drugs target voltage-gated sodium channels, and their potent activity in inhibiting high-frequency firing has been attributed to their strong use-dependent blocking action. In chronic epilepsy, a loss of use-dependent block has emerged as a potential cellular mechanism of pharmacoresistance for anticonvulsants acting on voltage-gated sodium channels...
November 19, 2016: Epilepsia
https://www.readbyqxmd.com/read/27863381/probucol-prevents-atrial-ion-channel-remodeling-in-an-alloxan-induced-diabetes-rabbit-model
#18
Huaying Fu, Guangping Li, Changle Liu, Jian Li, Lijun Cheng, Wansong Yang, Gary Tse, Jichao Zhao, Tong Liu
Diabetes mellitus (DM) increases the risk of developing atrial fibrillation (AF), but the molecular mechanisms of diabetes-induced atrial remodeling processes have not been fully characterized. The aim of this study was to examine the mechanisms underlying atrial ion channel remodeling in alloxan-induced diabetes model in rabbits. A total of 40 Japanese rabbits were randomly assigned to a control group (C), alloxan-induced diabetic group (DM), probucol-treated control group (Control-P), and probucol-treated diabetic group (DM-P)...
November 14, 2016: Oncotarget
https://www.readbyqxmd.com/read/27861889/margatoxin-bound-quantum-dots-as-a-novel-inhibitor-of-the-voltage-gated-ion-channel-kv1-3
#19
Austin B Schwartz, Anshika Kapur, Wentao Wang, Zhenbo Huang, Erminia Fardone, Goutam Palui, Hedi Mattoussi, Debra Ann Fadool
Venom-derived ion channel inhibitors have strong channel selectivity, potency, and stability; however, tracking delivery to their target can be challenging. Herein, we utilized luminescent quantum dots (QDs) conjugated to margatoxin (MgTx) as a traceable vehicle to target a voltage-dependent potassium channel, Kv1.3, which has a select distribution and well characterized role in immunity, glucose metabolism, and sensory ability. We screened both unconjugated (MgTx) and conjugated MgTx (QD-MgTx) for their ability to inhibit Shaker channels Kv1...
November 8, 2016: Journal of Neurochemistry
https://www.readbyqxmd.com/read/27861438/cardiotoxic-antiemetics-metoclopramide-and-domperidone-block-cardiac-voltage-gated-na-channels
#20
Carsten Stoetzer, Marc Voelker, Thorben Doll, Joerg Heineke, Florian Wegner, Andreas Leffler
BACKGROUND: Metoclopramide and domperidone are prokinetic and antiemetic substances often used in clinical practice. Although domperidone has a more favorable side effect profile and is considered the first-line agent, severe cardiac side effects were reported during the administration of both substances. Cardiac Na channels are common targets of therapeutics inducing cardiotoxicity. Therefore, the aim of this study was to investigate whether the differential cardiotoxicities of metoclopramide and domperidone correlate with the block of Na channels...
November 17, 2016: Anesthesia and Analgesia
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