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Potassium current voltage clamp

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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
#1
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/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
#2
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/28443815/molecular-mechanism-of-voltage-dependent-potentiation-of-kcnh-potassium-channels
#3
Gucan Dai, William N Zagotta
EAG-like (ELK) voltage-gated potassium channels are abundantly expressed in the brain. These channels exhibit a behavior called voltage-dependent potentiation (VDP), which appears to be a specialization to dampen the hyperexitability of neurons. VDP manifests as a potentiation of current amplitude, hyperpolarizing shift in voltage sensitivity, and slowing of deactivation in response to a depolarizing prepulse. Here we show that VDP of D. rerio ELK channels involves the structural interaction between the intracellular N-terminal eag domain and C-terminal CNBHD...
April 27, 2017: ELife
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
#4
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/28429218/modification-of-calcium-activated-chloride-currents-in-cerebellar-purkinje-neurons
#5
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 2017: Bulletin of Experimental Biology and Medicine
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
#6
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
#7
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/28404730/not-flying-blind-a-comparative-study-of-photoreceptor-function-in-flying-and-non-flying-cockroaches
#8
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/28383569/gating-mechanisms-underlying-deactivation-slowing-by-two-kcnq1-atrial-fibrillation-mutations
#9
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/28374528/calcium-activated-bkca-channels-govern-dynamic-membrane-depolarizations-of-horizontal-cells-in-rodent-retina
#10
Xiaoping Sun, Arlene A Hirano, Nicholas C Brecha, Steven Barnes
Large conductance, calcium-activated potassium (BKCa ) channels have numerous roles in neurons including the regulation of membrane excitability, intracellular [Ca(2+) ] regulation, and neurotransmitter release. In the retina, they have been identified in photoreceptors, bipolar cells, amacrine cells, and ganglion cells, but have not been conclusively identified in mammalian horizontal cells. We found that outward current recorded between -30 mV and +60 mV is carried primarily in BKCa channels in isolated horizontal cells of rats and mice...
April 4, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28367595/ionic-currents-influencing-spontaneous-firing-and-pacemaker-frequency-in-dopamine-neurons-of-the-ventrolateral-periaqueductal-gray-and-dorsal-raphe-nucleus-vlpag-drn-a-voltage-clamp-and-computational-modelling-study
#11
Antonios G Dougalis, Gillian A C Matthews, Birgit Liss, Mark A Ungless
Dopamine (DA) neurons of the ventrolateral periaqueductal gray (vlPAG) and dorsal raphe nucleus (DRN) fire spontaneous action potentials (APs) at slow, regular patterns in vitro but a detailed account of their intrinsic membrane properties responsible for spontaneous firing is currently lacking. To resolve this, we performed a voltage-clamp electrophysiological study in brain slices to describe their major ionic currents and then constructed a computer model and used simulations to understand the mechanisms behind autorhythmicity in silico...
June 2017: Journal of Computational Neuroscience
https://www.readbyqxmd.com/read/28361268/resveratrol-attenuates-a%C3%AE-induced-early-hippocampal-neuron-excitability-impairment-via-recovery-of-function-of-potassium-channels
#12
Hongqiang Yin, Hui Wang, Hui Zhang, Na Gao, Tao Zhang, Zhuo Yang
Alzheimer's disease (AD) is an age-related neurodegenerative disease. Amyloid-β (Aβ) is not only the morphological hallmark but also the initiator of the pathology process of AD. As a natural compound found in grapes, resveratrol shows a protective effect on the pathophysiology of AD, but the underlying mechanism is not very clear. This study was to investigate whether resveratrol could attenuate Aβ-induced early impairment in hippocampal neuron excitability and the underlying mechanism. The excitability and voltage-gated potassium currents were examined in rat hippocampal CA1 pyramidal neurons by using whole-cell patch-clamp technique...
March 30, 2017: Neurotoxicity Research
https://www.readbyqxmd.com/read/28349975/mechanism-of-functional-interaction-between-potassium-channel-kv1-3-and-sodium-channel-navbeta1-subunit
#13
Tomoya Kubota, Ana M Correa, Francisco Bezanilla
The voltage-gated potassium channel subfamily A member 3 (Kv1.3) dominantly expresses on T cells and neurons. Recently, the interaction between Kv1.3 and NavBeta1 subunits has been explored through ionic current measurements, but the molecular mechanism has not been elucidated yet. We explored the functional interaction between Kv1.3 and NavBeta1 through gating current measurements using the Cut-open Oocyte Voltage Clamp (COVC) technique. We showed that the N-terminal 1-52 sequence of hKv1.3 disrupts the channel expression on the Xenopus oocyte membrane, suggesting a potential role as regulator of hKv1...
March 28, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28327344/direct-activation-of-ca-2-and-voltage-gated-potassium-channels-of-large-conductance-by-anandamide-in-endothelial-cells-does-not-support-the-presence-of-endothelial-atypical-cannabinoid-receptor
#14
Alexander I Bondarenko, Olga Panasiuk, Iryna Okhai, Fabrizio Montecucco, Karim J Brandt, Francois Mach
Endocannabinoid anandamide induces endothelium-dependent relaxation commonly attributed to stimulation of the G-protein coupled endothelial anandamide receptor. The study addressed the receptor-independent effect of anandamide on large conductance Ca(2+)-dependent K(+) channels expressed in endothelial cell line EA.hy926. Under resting conditions, 10µM anandamide did not significantly influence the resting membrane potential. In a Ca(2+)-free solution the cells were depolarized by ~10mV. Further administration of 10µM anandamide hyperpolarized the cells by ~8mV...
March 19, 2017: European Journal of Pharmacology
https://www.readbyqxmd.com/read/28325748/halogenated-ether-alcohol-and-alkane-anesthetics-activate-task-3-tandem-pore-potassium-channels-likely-through-a-common-mechanism
#15
Anita Luethy, James D Boghosian, Rithu Srikantha, Joseph F Cotten
TASK-3 (KCNK9) tandem pore potassium channel function is activated by halogenated anesthetics through binding at a putative anesthetic binding cavity. To understand pharmacological requirements for TASK-3 activation, we studied the concentration-response of TASK-3 to several anesthetics (isoflurane, desflurane, sevoflurane, halothane, α-chloralose, 2,2,2-trichloroethanol(TCE), and chloral hydrate), to ethanol, and to a panel of halogenated methanes and alcohols. We used mutagenesis to probe the anesthetic binding cavity as observed in a TASK-3 homology model...
March 21, 2017: Molecular Pharmacology
https://www.readbyqxmd.com/read/28315292/hypoxic-culture-promotes-dopaminergic-neuronal-differentiation-of-nasal-olfactory-mucosa-mesenchymal-stem-cells-via-up-regulation-of-hypoxia-inducible-factor-1%C3%AE
#16
Yi Zhuo, Lei Wang, Lite Ge, Xuan Li, Ping Chen, Da Duan, Xiaohua Teng, Miao Jiang, Kai Liu, Ting Yuan, Pei Wu, Hao Wang, Yujia Deng, Huali Xie, Ying Xia, Ming Lu
<p><b>Background</b> Olfactory mucosa mesenchymal stem cells (OM-MSCs) display significant clonogenicactivity 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) is thus an attractive topic of research.</p><p><b>Methods</b> 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 (HI group)...
March 17, 2017: Cell Transplantation
https://www.readbyqxmd.com/read/28306530/ascorbic-acid-does-not-modulate-potassium-currents-in-cultured-human-lymphocytes
#17
Saravanakumar Snekalatha, Praghalathan Kanthakumar
BACKGROUND: Ascorbic acid (AA) is known to modulate lymphocyte function, but the mechanism of action is not clearly understood. As voltage-gated potassium currents play an important role in lymphocyte function, the effect of AA on voltage-gated potassium currents was studied. METHODS: Peripheral blood mononuclear cells were cultured in the presence of increasing concentrations of AA (0, 0.125, 0.25, 0.5, and 1 mM). Potassium currents in resting lymphocytes were studied by whole cell patch clamp technique using a depolarizing protocol...
March 17, 2017: Journal of Basic and Clinical Physiology and Pharmacology
https://www.readbyqxmd.com/read/28288868/inhibition-of-kir4-1-potassium-channels-by-quinacrine
#18
Leticia G Marmolejo-Murillo, Iván A Aréchiga-Figueroa, Meng Cui, Eloy G Moreno-Galindo, Ricardo A Navarro-Polanco, José A Sánchez-Chapula, Tania Ferrer, Aldo A Rodríguez-Menchaca
Inwardly rectifying potassium (Kir) channels are expressed in many cell types and contribute to a wide range of physiological processes. Particularly, Kir4.1 channels are involved in the astroglial spatial potassium buffering. In this work, we examined the effects of the cationic amphiphilic drug quinacrine on Kir4.1 channels heterologously expressed in HEK293 cells, employing the patch clamp technique. Quinacrine inhibited the currents of Kir4.1 channels in a concentration and voltage dependent manner. In inside-out patches, quinacrine inhibited Kir4...
May 15, 2017: Brain Research
https://www.readbyqxmd.com/read/28282785/peimine-inhibits-herg-potassium-channels-through-the-channel-inactivation-states
#19
Liandi Kan, Wei Zhao, Lanying Pan, Jianwei Xu, Qingmao Chen, Kai Xu, Liping Xiao, Yuan Chen
BACKGROUND AND OBJECTIVE: Fritillaria is a Chinese traditional herb. It has a long history and many medicinal usages including antitussive, anti-inflammatory and pain relieving actions. It is also used as food. However, its cardiac safety has not been tested. Peimine is one of the main active compounds of Fritillaria. To be listed as an herb in the Chinese Pharmacopoeia, a special minimal percentage of Peimine in the dry sample of Fritillaria is required. The main concern for cardiac safety determination is the possible inhibition of hERG ion channels...
May 2017: Biomedicine & Pharmacotherapy, Biomédecine & Pharmacothérapie
https://www.readbyqxmd.com/read/28265686/inhibition-of-cloned-herg-potassium-channels-by-risperidone-and-paliperidone
#20
Hong Joon Lee, Jin-Sung Choi, Bok Hee Choi, Sang June Hahn
Risperidone and one of its active metabolites, paliperidone, are widely used for the treatment of schizophrenia. We used a patch-clamp study to investigate the effects of paliperidone on hERG potassium channels expressed in HEK cells. Western blot analyses were used to study the effects of risperidone and paliperidone on hERG and hERG 3.1 isoform channel trafficking. Risperidone and paliperidone inhibited the hERG tail currents in a concentration-dependent manner with IC50 values of 0.16 and 0.57 μM, respectively...
March 6, 2017: Naunyn-Schmiedeberg's Archives of Pharmacology
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