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Potassium current voltage clamp

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https://www.readbyqxmd.com/read/29156097/4-aminopyridine-a-pan-kv-channel-inhibitor-that-enhances-kv7-4-currents-and-inhibits-noradrenaline-mediated-contraction-of-rat-mesenteric-small-arteries
#1
Makhala M Khammy, Sukhan Kim, Bo H Bentzen, Soojung Lee, Inyeoung Choi, Christian Aalkjaer, Thomas A Jepps
BACKGROUND AND PURPOSE: Kv7.4 and Kv7.5 channels are regulators of vascular tone. 4-aminopyridine (4-AP) is considered a broad inhibitor of voltage-gated potassium (KV ) channels, with little inhibitory effect on Kv7 family members at millimolar concentrations. However, the effect of 4-AP on Kv7 channels has not been systematically studied. The aim of this study was to investigate the pharmacological activity of 4-AP on Kv7.4 and Kv7.5 channels and characterise the effect of 4-AP on rat resistance arteries...
November 20, 2017: British Journal of Pharmacology
https://www.readbyqxmd.com/read/29133173/effects-of-norquetiapine-the-active-metabolite-of-quetiapine-on-cloned-herg-potassium-channels
#2
Hong Joon Lee, Jin-Sung Choi, Bok Hee Choi, Sang June Hahn
Quetiapine is an atypical antipsychotic drug that is widely used for the treatment of schizophrenia. It is mainly metabolized by a cytochrome P450 system in the liver. Norquetiapine is a major active metabolite in humans with a pharmacological profile that differs distinctly from that of quetiapine. We used the whole-cell patch-clamp technique to investigate the effects of norquetiapine on hERG channels that are stably expressed in HEK cells. Quetiapine and norquetiapine inhibited the hERG tail currents at -50mV in a concentration-dependent manner with IC50 values of 8...
November 11, 2017: Neuroscience Letters
https://www.readbyqxmd.com/read/29128793/phytochemicals-genistein-and-capsaicin-modulate-kv2-1-channel-gating
#3
Iván A Aréchiga-Figueroa, Rita Morán-Zendejas, Mayra Delgado-Ramírez, Aldo A Rodríguez-Menchaca
BACKGROUND: Phytochemicals are a large group of plant-derived compounds that have a broad range of pharmacological effects. Some of these effects are derived from their action on transport proteins, including ion channels. The present study investigates the effects of the phytochemicals genistein and capsaicin on voltage-gated potassium Kv2.1 channels. METHODS: The whole-cell patch clamp technique was used to explore the regulation of Kv2.1 channels expressed in HEK293 cells by genistein and capsaicin...
June 3, 2017: Pharmacological Reports: PR
https://www.readbyqxmd.com/read/29117522/the-fast-component-of-herg-gating-charge-an-interaction-between-d411-in-the-s1-and-s4-residues
#4
Ying Dou, Logan C Macdonald, Yue Wu, David Fedida
Kv11.1 (hERG) is a voltage-gated potassium channel that shows very slow ionic current activation kinetics, and an unusual underlying biphasic gating charge movement with fast and slow components that differ greatly in time course. The structural basis and role of the fast component of gating charge (Qfast) is unclear, and its relationship to the slow activation of hERG channels is not understood. In this study we have used the cut-open oocyte voltage-clamp technique to investigate the relationship of fast gating charge movement-to-residue interactions between D411 at the bottom of the S1, and lower S4 domain charged and uncharged residues...
November 7, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/29097440/desensitization-and-tolerance-of-mu-opioid-receptors-on-pontine-kolliker-fuse-neurons
#5
Erica S Levitt, John T Williams
Acute desensitization of mu opioid receptors is thought to be an initial step in the development of tolerance to opioids. Given the resistance of the respiratory system to develop tolerance, desensitization of neurons in the Kölliker-Fuse (KF), a key area in the respiratory circuit, was examined. The activation of G protein-coupled inwardly rectifying potassium (GIRK) current was measured using whole-cell voltage-clamp recordings from KF and locus coeruleus (LC) neurons contained in acute rat brain slices...
November 2, 2017: Molecular Pharmacology
https://www.readbyqxmd.com/read/29081746/the-natural-flavone-acacetin-blocks-small-conductance-ca-2-activated-k-channels-stably-expressed-in-hek-293-cells
#6
Kui-Hao Chen, Hui Liu, Hai-Ying Sun, Man-Wen Jin, Guo-Sheng Xiao, Yan Wang, Gui-Rong Li
The natural flavone acacetin inhibits several voltage-gated potassium currents in atrial myocytes, and has anti-atrial fibrillation (AF) effect in experimental AF models. The present study investigates whether acacetin inhibits the Ca(2+)-activated potassium (KCa) currents, including small conductance (SKCa1, SKCa2, and SKCa3), intermediate conductance (IKCa), and large-conductance (BKCa) channels stably expressed in HEK 293 cells. The effects of acacetin on these KCa channels were determined with a whole-cell patch voltage-clamp technique...
2017: Frontiers in Pharmacology
https://www.readbyqxmd.com/read/29078287/pip2-mediates-functional-coupling-and-pharmacology-of-neuronal-kcnq-channels
#7
Robin Y Kim, Stephan A Pless, Harley T Kurata
Retigabine (RTG) is a first-in-class antiepileptic drug that suppresses neuronal excitability through the activation of voltage-gated KCNQ2-5 potassium channels. Retigabine binds to the pore-forming domain, causing a hyperpolarizing shift in the voltage dependence of channel activation. To elucidate how the retigabine binding site is coupled to changes in voltage sensing, we used voltage-clamp fluorometry to track conformational changes of the KCNQ3 voltage-sensing domains (VSDs) in response to voltage, retigabine, and PIP2...
November 7, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/29072259/barbaloin-inhibits-ventricular-arrhythmias-in-rabbits-by-modulating-voltage-gated-ion-channels
#8
Zhen-Zhen Cao, You-Jia Tian, Jie Hao, Pei-Hua Zhang, Zhi-Pei Liu, Wan-Zhen Jiang, Meng-Liu Zeng, Pei-Pei Zhang, Ji-Hua Ma
Barbaloin (10-β-D-glucopyranosyl-1,8-dihydroxy-3-(hydroxymethyl)-9(10H)-anthracenone) is extracted from the aloe plant and has been reported to have anti-inflammatory, antitumor, antibacterial, and other biological activities. Here, we investigated the effects of barbaloin on cardiac electrophysiology, which has not been reported thus far. Cardiac action potentials (APs) and ionic currents were recorded in isolated rabbit ventricular myocytes using whole-cell patch-clamp technique. Additionally, the antiarrhythmic effect of barbaloin was examined in Langendorff-perfused rabbit hearts...
October 26, 2017: Acta Pharmacologica Sinica
https://www.readbyqxmd.com/read/29055091/functional-interaction-of-junctophilin-2-with-small-conductance-ca-2-activated-potassium-channel-subtype-2-sk2-in-mouse-cardiac-myocytes
#9
Hong K Fan, Tian X Luo, Wei D Zhao, Yong H Mu, Yang Yang, Wen J Guo, Hui Y Tu, Qian Zhang
AIM: Junctophilins (JPs), a protein family of the junctional membrane complex, maintain the close conjunction between cell surface and intracellular membranes in striate muscle cells mediating the cross talk between extracellular Ca(2+) entry and intracellular Ca(2+) release. The small conductance Ca(2+) -activated K(+) channels are activated by the intracellular calcium and play an essential role in the cardiac action potential profile. Molecular mechanisms of regulation of the SK channels are still uncertain...
October 21, 2017: Acta Physiologica
https://www.readbyqxmd.com/read/29046423/the-intrinsic-physiology-of-inhibitory-neurons-changes-over-auditory-development
#10
Briana J Carroll, Richard Bertram, Richard L Hyson
During auditory development, changes in membrane properties promote the ability of excitatory neurons in the brainstem to code aspects of sound, including the level and timing of a stimulus. Some of these changes coincide with hearing onset, suggesting that sound-driven neural activity produces developmental plasticity of ion channel expression. While it is known that the coding properties of excitatory neurons are modulated by inhibition in the mature system, it is unknown whether there are also developmental changes in the membrane properties of brainstem inhibitory neurons...
October 18, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/28987626/no-involvement-in-the-inhibition-of-ghrelin-on-voltage-dependent-potassium-currents-in-rat-hippocampal-cells
#11
Yong Lu, Shaokang Dang, Xu Wang, Junli Zhang, Lin Zhang, Qian Su, Huiping Zhang, Tianwei Lin, Xiaoxiao Zhang, Yurong Zhang, Hongli Sun, Zhongliang Zhu, Hui Li
Ghrelin is a peptide hormone that plays an important role in promoting appetite, regulating distribution and rate of use of energy, cognition, and mood disorders, but the relevant neural mechanisms of these function are still not clear. In this study, we examined the effect of ghrelin on voltage-dependent potassium (K(+)) currents in hippocampal cells of 1-3 days SD rats by whole-cell patch-clamp technique, and discussed whether NO was involved in this process. The results showed that ghrelin significantly inhibited the voltage-dependent K(+) currents in hippocampal cells, and the inhibitory effect was more significant when L-arginine was co-administered...
October 4, 2017: Brain Research
https://www.readbyqxmd.com/read/28982705/sk-channels-regulate-resting-properties-and-signaling-reliability-of-a-developing-fast-spiking-neuron
#12
Yihui Zhang, Hai Huang
Reliable and precise signal transmission is essential in circuits of the auditory brainstem to encode timing with submillisecond accuracy. Globular bushy cells reliably and faithfully transfer spike signals to the principal neurons of the medial nucleus of the trapezoid body (MNTB) through the giant glutamatergic synapse, the calyx of Held. Thus, the MNTB works as a relay nucleus that preserves the temporal pattern of firing at high frequency. Using whole-cell patch-clamp recordings, we observed a K(+) conductance mediated by small-conductance calcium-activated potassium (SK) channels in the MNTB neurons from rats of either sex...
November 1, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28964116/revealing-kinetics-and-state-dependent-binding-properties-of-ikur-targeting-drugs-that-maximize-atrial-fibrillation-selectivity
#13
Nicholas Ellinwood, Dobromir Dobrev, Stefano Morotti, Eleonora Grandi
The KV1.5 potassium channel, which underlies the ultra-rapid delayed-rectifier current (IKur) and is predominantly expressed in atria vs. ventricles, has emerged as a promising target to treat atrial fibrillation (AF). However, while numerous KV1.5-selective compounds have been screened, characterized, and tested in various animal models of AF, evidence of antiarrhythmic efficacy in humans is still lacking. Moreover, current guidelines for pre-clinical assessment of candidate drugs heavily rely on steady-state concentration-response curves or IC50 values, which can overlook adverse cardiotoxic effects...
September 2017: Chaos
https://www.readbyqxmd.com/read/28940182/bk-%C3%AE-1-subunit-dependent-facilitation-of-ethanol-inhibition-of-bk-current-and-cerebral-artery-constriction-is-mediated-by-the-%C3%AE-1-transmembrane-domain-2
#14
Guruprasad Kuntamallappanavar, Alex M Dopico
BACKGROUND AND PURPOSE: Ethanol at concentrations obtained in the circulation during moderate-heavy episodic drinking (30-60 mM) causes cerebral artery constriction in several species, including humans. In rodents, ethanol-induced cerebral artery constriction results from ethanol inhibition of large conductance voltage/Ca(2+)i -gated K(+) (BK) channels in cerebral artery myocytes. Moreover, the smooth muscle-abundant BK β1 accessory subunit is required for ethanol to inhibit cerebral artery myocyte BK channels under physiological Ca(2+)i and voltages and thus constrict cerebral arteries...
September 23, 2017: British Journal of Pharmacology
https://www.readbyqxmd.com/read/28919864/%C3%AE-subunits-control-the-effects-of-human-kv4-3-potassium-channel-phosphorylation
#15
Geoffrey W Abbott
The transient outward K(+) current, Ito, activates early in the cardiac myocyte action potential, to begin repolarization. Human Ito is generated primarily by two Kv4.3 potassium channel α subunit splice variants (Kv4.3L and Kv4.3S) that diverge only by a C-terminal, membrane-proximal, 19-residue stretch unique to Kv4.3L. Protein kinase C (PKC) phosphorylation of threonine 504 within the Kv4.3L-specific 19-residues mediates α-adrenergic inhibition of Ito in human heart. Kv4.3 is regulated in human heart by various β subunits, including cytosolic KChIP2b and transmembrane KCNEs, yet their impact on the functional effects of human Kv4...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/28902151/apetx4-a-novel-sea-anemone-toxin-and-a-modulator-of-the-cancer-relevant-potassium-channel-kv10-1
#16
Lien Moreels, Steve Peigneur, Diogo T Galan, Edwin De Pauw, Lászlo Béress, Etienne Waelkens, Luis A Pardo, Loïc Quinton, Jan Tytgat
The human ether-à-go-go channel (hEag1 or KV10.1) is a cancer-relevant voltage-gated potassium channel that is overexpressed in a majority of human tumors. Peptides that are able to selectively inhibit this channel can be lead compounds in the search for new anticancer drugs. Here, we report the activity-guided purification and electrophysiological characterization of a novel KV10.1 inhibitor from the sea anemone Anthopleura elegantissima. Purified sea anemone fractions were screened for inhibitory activity on KV10...
September 13, 2017: Marine Drugs
https://www.readbyqxmd.com/read/28901191/hypoxic-culture-promotes-dopaminergic-neuronal-differentiation-of-nasal-olfactory-mucosa-mesenchymal-stem-cells-via-upregulation-of-hypoxia-inducible-factor-1%C3%AE
#17
Yi Zhuo, Lei Wang, Lite Ge, Xuan Li, Da Duan, Xiaohua Teng, Miao Jiang, Kai Liu, Ting Yuan, Pei Wu, Hao Wang, Yujia Deng, Huali Xie, Ping Chen, Ying Xia, Ming Lu
Olfactory mucosa mesenchymal stem cells (OM-MSCs) display significant clonogenic activity 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) are thus an attractive topic of research. 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 (OCM; HI group). The normal induction (NI) group was cultured in O2 at ambient air level (21%)...
August 2017: Cell Transplantation
https://www.readbyqxmd.com/read/28888063/sumo-co-expression-modifies-kv-11-1-channel-activity
#18
Annette Buur Steffensen, Martin Nybo Andersen, Nancy Mutsaers, Amer Mujezinovic, Nicole Schmitt
AIM: The voltage-gated potassium channel KV 11.1 is the molecular basis for the IKr current which plays an important role in cardiac physiology. Its malfunction is associated with both inherited and acquired cardiac arrhythmias. Native currents differ from those in experimental models, suggesting additional regulatory mechanisms. We hypothesised that the post-translational modification sumoylation finetunes channel activity. METHODS: The functional effects of sumoylation on KV 11...
September 9, 2017: Acta Physiologica
https://www.readbyqxmd.com/read/28878623/mechanisms-of-spontaneous-climbing-fiber-discharge-evoked-pauses-and-output-modulation-of-cerebellar-purkinje-cell-in-mice
#19
Xian-Hua Jin, Hong-Wei Wang, Xin-Yuan Zhang, Chun-Ping Chu, Yuan-Zhe Jin, Song-Biao Cui, De-Lai Qiu
Climbing fiber (CF) afferents modulate the frequency and patterns of cerebellar Purkinje cell (PC) simple spike (SS) activity, but its mechanism is unclear. In the present study, we investigated the mechanisms of spontaneous CF discharge-evoked pauses and the output modulation of cerebellar PCs in urethane-anesthetized mice using in vivo whole-cell recording techniques and pharmacological methods. Under voltage-clamp recording conditions, spontaneous CF discharge evoked strong inward currents followed by small conductance calcium-activated potassium (SK) channels that mediated outward currents...
2017: Frontiers in Cellular Neuroscience
https://www.readbyqxmd.com/read/28863155/electrophysiological-characteristics-of-pressure-overload-induced-cardiac-hypertrophy-and-its-influence-on-ventricular-arrhythmias
#20
Xiaowei Chen, Mu Qin, Weifeng Jiang, Yu Zhang, Xu Liu
OBJECTIVE: To explore the cardiac electrophysiological characteristics of cardiac hypertrophy and its influence on the occurrence of ventricular tachyarrhythmias. METHODS: Adult C57BL6 mice were randomly divided into a surgery group and a control group. Thoracic aortic constriction was performed on mice in the surgery group, and cardiac anatomical and ultrasonic evaluations were performed to confirm the success of the cardiac hypertrophy model 4 weeks after the operation...
2017: PloS One
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