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Potassium current voltage clamp

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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
#1
Guruprasad Kuntamallappanavar, Alex M Dopico
BACKGROUND AND PURPOSE: Ethanol at concentrations obtained in 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 potassium (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
#2
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
#3
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
#4
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
#5
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
#6
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
#7
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
https://www.readbyqxmd.com/read/28843833/strain-specific-differences-in-the-development-of-neuronal-excitability-in-the-mouse-ventral-nucleus-of-the-trapezoid-body
#8
James L Sinclair, Margaret Barnes-Davies, Conny Kopp-Scheinpflug, Ian D Forsythe
This investigation compared the development of neuronal excitability in the ventral nucleus of the trapezoid body (VNTB) between two strains of mice with differing progression rates for age-related hearing loss. In contrast to CBA/Ca (CBA) mice, the C57BL/6J (C57) strain are subject to hearing loss from a younger age and are more prone to damage from sound over-exposure. Higher firing rates in the medial olivocochlear system (MOC) are associated with protection from loud sounds and these cells are located in the VNTB...
August 18, 2017: Hearing Research
https://www.readbyqxmd.com/read/28808020/kcne1-and-kcne3-modulate-kcnq1-channels-by-affecting-different-gating-transitions
#9
Rene Barro-Soria, Rosamary Ramentol, Sara I Liin, Marta E Perez, Robert S Kass, H Peter Larsson
KCNE β-subunits assemble with and modulate the properties of voltage-gated K(+) channels. In the heart, KCNE1 associates with the α-subunit KCNQ1 to generate the slowly activating, voltage-dependent potassium current (IKs) in the heart that controls the repolarization phase of cardiac action potentials. By contrast, in epithelial cells from the colon, stomach, and kidney, KCNE3 coassembles with KCNQ1 to form K(+) channels that are voltage-independent K(+) channels in the physiological voltage range and important for controlling water and salt secretion and absorption...
August 29, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28724979/impairment-of-coronary-endothelial-function-by-hypoxia-reoxygenation-involves-trpc3-inhibition-mediated-kca-channel-dysfunction-implication-in-ischemia-reperfusion-injury
#10
Xiang-Chong Wang, Wen-Tao Sun, Jie Fu, Jun-Hao Huang, Cheuk-Man Yu, Malcolm John Underwood, Guo-Wei He, Qin Yang
Despite increasing knowledge of the significance of calcium-activated potassium (KCa) and canonical transient receptor potential (TRPC) channels in endothelial physiology, no studies so far have investigated the link between these two distinct types of channels in the control of vascular tone in pathological conditions. We previously demonstrated that hypoxia-reoxygenation (H-R) inhibits endothelial KCa and TRPC3 channels in porcine coronary arteries (PCAs). The present study further investigated whether modulation of TRPC3 is involved in H-R-induced KCa channel inhibition and associated vasodilatory dysfunction using approaches of wire myography, whole-cell voltage-clamp, and coimmunoprecipitation...
July 19, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28724748/depressed-synaptic-transmission-and-reduced-vesicle-release-sites-in-huntington-s-disease-neuromuscular-junctions
#11
Ahmad Khedraki, Eric J Reed, Shannon H Romer, Qingbo Wang, William Romine, Mark M Rich, Robert J Talmadge, Andrew A Voss
Huntington's disease (HD) is a progressive and fatal degenerative disorder that results in debilitating cognitive and motor dysfunction. Most HD studies have focused on degeneration of the CNS. We previously discovered that skeletal muscle from transgenic R6/2 HD mice is hyperexcitable due to decreased chloride and potassium conductances. The progressive and early onset of these defects suggest a primary myopathy in HD. In this study, we examined the relationship between neuromuscular transmission and skeletal muscle hyperexcitability...
August 23, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28711494/development-of-membrane-ion-channels-during-neural-differentiation-from-human-embryonic-stem-cells
#12
Sara Mirsadeghi, Ebrahim Shahbazi, Katayoun Hemmesi, Shiva Nemati, Hossein Baharvand, Javad Mirnajafi-Zadeh, Sahar Kiani
OBJECTIVE: For human embryonic stem cells (hESCs) to differentiate into neurons, enormous changes has to occur leading to trigger action potential and neurotransmitter release. We attempt to determine the changes in expression of voltage gated channels (VGCs) and their electrophysiological properties during neural differentiation. MATERIALS AND METHODS: The relative expressions of α-subunit of voltage gated potassium, sodium and calcium channels were characterized by qRT-PCR technique...
September 9, 2017: Biochemical and Biophysical Research Communications
https://www.readbyqxmd.com/read/28701925/postsynaptic-gaba-b-receptors-contribute-to-the-termination-of-giant-depolarizing-potentials-in-ca3-neonatal-rat-hippocampus
#13
Ilgam Khalilov, Marat Minlebaev, Marat Mukhtarov, Elvira Juzekaeva, Roustem Khazipov
During development, hippocampal CA3 network generates recurrent population bursts, so-called Giant Depolarizing Potentials (GDPs). GDPs are characterized by synchronous depolarization and firing of CA3 pyramidal cells followed by afterhyperpolarization (GDP-AHP). Here, we explored the properties of GDP-AHP in CA3 pyramidal cells using gramicidin perforated patch clamp recordings from neonatal rat hippocampal slices. We found that GDP-AHP occurs independently of whether CA3 pyramidal cells fire action potentials (APs) or remain silent during GDPs...
2017: Frontiers in Cellular Neuroscience
https://www.readbyqxmd.com/read/28683073/high-throughput-electrophysiological-assays-for-voltage-gated-ion-channels-using-syncropatch-768pe
#14
Tianbo Li, Gang Lu, Eugene Y Chiang, Tania Chernov-Rogan, Jane L Grogan, Jun Chen
Ion channels regulate a variety of physiological processes and represent an important class of drug target. Among the many methods of studying ion channel function, patch clamp electrophysiology is considered the gold standard by providing the ultimate precision and flexibility. However, its utility in ion channel drug discovery is impeded by low throughput. Additionally, characterization of endogenous ion channels in primary cells remains technical challenging. In recent years, many automated patch clamp (APC) platforms have been developed to overcome these challenges, albeit with varying throughput, data quality and success rate...
2017: PloS One
https://www.readbyqxmd.com/read/28677751/effects-of-rmf-on-bkca-and-kv-channels-in-basilar-arterial-smooth%C3%A2-muscle-cells-of-shr
#15
Yan-Fei Qian, Yang Wang, Wei-Wei Tian, Sheng Wang, Lei Zhao, Li Li, Ke-Tao Ma, Jun-Qiang Si
The current study observed the effects and investigated the mechanism of remifentanil (RMF) on the isolated cerebral basilar arteries of spontaneously hypertensive rats (SHR) and Wistar‑Kyoto (WKY) rats. A pressure myograph system was used to observe and compare the effects of different concentrations of RMF (10‑10‑10‑5 mol/l) on the diameter changes of freshly isolated cerebral basilar arteries, which have been pre‑shrunk by phenylephrine (PE), an endothelium‑independent vasoconstrictor. Vascular smooth‑muscle cells of the cerebral basilar artery (BASMCs) were freshly obtained via enzymolysis...
September 2017: Molecular Medicine Reports
https://www.readbyqxmd.com/read/28673509/discovery-of-a-new-mexiletine-derived-agonist-of-the-herg-k-channel
#16
Roberta Gualdani, Maria Maddalena Cavalluzzi, Francesco Tadini-Buoninsegni, Giovanni Lentini
The human Ether-a-go-go Related Gene (hERG) potassium channel plays a central role in the rapid component (IKr) of cardiac action potential repolarization phase. A large number of structurally different compounds block hERG and cause a high risk of arrhythmias. Among the drugs that block hERG channel, a few compounds have been identified as hERG channel activators. Such compounds may be useful, at least in theory, for the treatment of long term QT syndrome. Here we describe a new activator of hERG channel, named MC450...
October 2017: Biophysical Chemistry
https://www.readbyqxmd.com/read/28672906/t-lymphocyte-kv1-3-channel-activation-triggers-the-nlrp3-inflammasome-signaling-pathway-in-hypertensive-patients
#17
Jian Zhu, Yan Yang, Si-Gan Hu, Qiu-Bing Zhang, Jie Yu, Yuan-Ming Zhang
The aim of the current study was to investigate the correlation between voltage-gated potassium 1.3 (Kv1.3) channel of peripheral blood T-lymphocytes and the NLR family pyrin domain containing 3 (NLRP3) inflammasome pathway in hypertensive patients. Peripheral blood samples from the hypertensive Kazakh patients (n=30) and healthy Kazakh subjects (n=30) were collected. The T lymphocytes and serum were separated, and the state of Kv1.3 channels was detected using the patch-clamp technique. Reverse transcription-quantitative polymerase chain reaction and western blot analyses were used to detect the mRNA and protein expression levels of key molecules [NLRP3, caspase-1 and interleuking (IL)-β] in the lymphocyte NLRP3 inflammasome pathway, while serum IL-1β content was measured by ELISA assay...
July 2017: Experimental and Therapeutic Medicine
https://www.readbyqxmd.com/read/28668511/voltage-sensitive-potassium-channels-expressed-after-20-hydroxyecdysone-treatment-of-a-mosquito-cell-line
#18
Lacey J Jenson, Baonan Sun, Jeffrey R Bloomquist
The goal of this research was to express receptors and ion channels in hormone-treated insect cell lines. Treatment of Anopheles gambiae Sua1B cells with 20-hydroxyecdysone showed an inhibition of cell growth over a time course of three days, with no change in cellular morphology. The effect of 20-hydroxyecdysone was enhanced in the presence of the potassium channel blocker 4-aminopyridine, but not tetraethylammonium. Concentration-response curves of 4-aminopyridine in the presence of 42 μM (1 mg/ml) 20-hydroxyecdysone showed similar IC50 values (6-10 μM) across 3 day exposures...
August 2017: Insect Biochemistry and Molecular Biology
https://www.readbyqxmd.com/read/28666963/a-novel-kcna1-mutation-in-a-patient-with-paroxysmal-ataxia-myokymia-painful-contractures-and-metabolic-dysfunctions
#19
Paola Imbrici, Concetta Altamura, Francesca Gualandi, Giuseppe Felice Mangiatordi, Marcella Neri, Giovanni De Maria, Alessandra Ferlini, Alessandro Padovani, Maria Cristina D'Adamo, Orazio Nicolotti, Mauro Pessia, Diana Conte, Massimiliano Filosto, Jean-Francois Desaphy
Episodic ataxia type 1 (EA1) is a human dominant neurological syndrome characterized by continuous myokymia, episodic attacks of ataxic gait and spastic contractions of skeletal muscles that can be triggered by emotional stress and fatigue. This rare disease is caused by missense mutations in the KCNA1 gene coding for the neuronal voltage gated potassium channel Kv1.1, which contributes to nerve cell excitability in the cerebellum, hippocampus, cortex and peripheral nervous system. We identified a novel KCNA1 mutation, E283K, in an Italian proband presenting with paroxysmal ataxia and myokymia aggravated by painful contractures and metabolic dysfunctions...
June 28, 2017: Molecular and Cellular Neurosciences
https://www.readbyqxmd.com/read/28648645/functional-interaction-of-the-two-pore-domain-potassium-channel-task-1-and-caveolin-3
#20
Chen Kang, Victor A Hernandez, Keli Hu
The two-pore domain potassium channel TASK-1 is strongly expressed in the heart and has been shown to modulate the resting membrane potential and action potential. However, little is known about the regulation of TASK-1 channels. The present study was designed to determine whether TASK-1 is modulated by caveolin-3, a primary structural protein of cardiac caveolae. Functional studies with the whole-cell voltage clamp technique showed that the expression of caveolin-3 decreased recombinant TASK-1 currents significantly in HEK293T cells, and this effect was prevented by co-expressing the dominant negative mutant caveolin-3 P104L...
June 23, 2017: Biochimica et Biophysica Acta
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