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Potassium current voltage clamp

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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
#1
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
#2
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 central nervous system. 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...
July 19, 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
#3
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...
July 12, 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
#4
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
#5
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
#6
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...
June 29, 2017: Molecular Medicine Reports
https://www.readbyqxmd.com/read/28673509/discovery-of-a-new-mexiletine-derived-agonist-of-the-herg-k-channel
#7
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...
June 19, 2017: Biophysical Chemistry
https://www.readbyqxmd.com/read/28672906/t-lymphocyte-kv1-3-channel-activation-triggers-the-nlrp3-inflammasome-signaling-pathway-in-hypertensive-patients
#8
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
#9
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...
June 28, 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
#10
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
#11
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
https://www.readbyqxmd.com/read/28626074/a-type-potassium-channels-contribute-to-prorenin-increase-of-firing-activity-in-hypothalamic-vasopressin-neurosecretory-neurons
#12
Soledad Pitra, Javier E Stern
Recent studies support an important contribution of prorenin (PR) and its receptor (PRR) to the regulation of hypothalamic sympathetic and neurosecretory outflows to the cardiovascular system, including systemic release of vasopressin (VP), both under physiological and cardiovascular disease conditions. Still, the identification of precise cellular mechanisms and neuronal/molecular targets remain unknown. We recently showed that PRR is expressed in VP neurons, and that their activation increases neuronal activity...
June 16, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28623618/endothelin-1-decreases-excitability-of-the-dorsal-root-ganglion-neurons-via-etb-receptor
#13
Nandkishor K Mule, Jitendra N Singh, Kunal U Shah, Anil Gulati, Shyam S Sharma
Endothelin-1 (ET-1) has been demonstrated to be a pro-nociceptive as well as an anti-nociceptive agent. However, underlying molecular mechanisms for these pain modulatory actions remain unclear. In the present study, we evaluated the ability of ET-1 to alter the nociceptor excitability using a patch clamp technique in acutely dissociated rat dorsal root ganglion (DRG) neurons. ET-1 produced an increase in threshold current to evoke an action potential (I threshold) and hyperpolarization of resting membrane potential (RMP) indicating decreased excitability of DRG neurons...
June 16, 2017: Molecular Neurobiology
https://www.readbyqxmd.com/read/28594440/calcium-signalling-in-medial-intercalated-cell-dendrites-and-spines
#14
Cornelia Strobel, Robert K P Sullivan, Peter Stratton, Pankaj Sah
KEY POINTS: Dendritic and spine calcium imaging in combination with electrophysiology in acute slices revealed that in medial intercalated cells of the amygdala: Action potentials back-propagate into the dendritic tree, but due to the presence of voltage-dependent potassium channels, probably Kv4.2 channels, attenuate over distance. A mixed population of AMPA receptors with rectifying and linear I-V relations are present at individual spines of a single neuron. Decay kinetics and pharmacology suggest tri-heteromeric NMDA receptors at basolateral-intercalated cell synapses...
June 8, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28550095/small-conductance-calcium-activated-potassium-current-in-normal-rabbit-cardiac-purkinje-cells
#15
Thomas A Reher, Zhuo Wang, Chia-Hsiang Hsueh, Po-Cheng Chang, Zhenwei Pan, Mohineesh Kumar, Jheel Patel, Jian Tan, Changyu Shen, Zhenhui Chen, Michael C Fishbein, Michael Rubart, Penelope Boyden, Peng-Sheng Chen
BACKGROUND: Purkinje cells (PCs) are important in cardiac arrhythmogenesis. Whether small-conductance calcium-activated potassium (SK) channels are present in PCs remains unclear. We tested the hypotheses that subtype 2 SK (SK2) channel proteins and apamin-sensitive SK currents are abundantly present in PCs. METHODS AND RESULTS: We studied 25 normal rabbit ventricles, including 13 patch-clamp studies, 4 for Western blotting, and 8 for immunohistochemical staining...
May 26, 2017: Journal of the American Heart Association
https://www.readbyqxmd.com/read/28539398/a-balance-of-outward-and-linear-inward-ionic-currents-is-required-for-the-generation-of-slow-wave-oscillations
#16
Jorge Golowasch, Amitabha Bose, Yinzheng Guan, Dalia Salloum, Andrea Roeser, Farzan Nadim
Regenerative inward currents help produce slow oscillations through a negative-slope conductance region of their current-voltage relationship that is well approximated by a linear negative conductance. We used dynamic clamp injections of a linear current with such conductance, INL, to explore why some neurons can generate intrinsic slow oscillations whereas others cannot. We addressed this question, in synaptically isolated neurons of the crab Cancer borealis, after blocking action potentials. The pyloric network consists of a distinct pacemaker and follower neurons, all of which express the same complement of ionic currents...
May 24, 2017: Journal of Neurophysiology
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
#17
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
#18
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...
August 2017: Naunyn-Schmiedeberg's Archives of Pharmacology
https://www.readbyqxmd.com/read/28443815/molecular-mechanism-of-voltage-dependent-potentiation-of-kcnh-potassium-channels
#19
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-modelling-of-arrhythmia-vulnerability
#20
Zane M Kalik, Joshua L Mike, Cassandra Slipski, Moriah Wright, Jozsi Z Jalics, Mark D Womble
What is the central question of this study? Regional variations of ventricular L-type calcium current (ICa-L ) amplitude may underlie the increased arrhythmia risk in adult females. Current amplitude variations have been described for the left ventricle but not for the right ventricle. What is the main finding and its importance? Adult female rabbit right ventricular base myocytes exhibit elevated ICa-L compared with female apex or male myocytes. Oestrogen upregulated ICa-L in cultured female myocytes. Mathematical simulations modelling long QT syndrome type 2 demonstrated that elevated ICa-L prolonged action potentials and induced early after-depolarizations...
April 24, 2017: Experimental Physiology
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