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https://www.readbyqxmd.com/read/28802123/clathrodin-hymenidin-and-oroidin-and-their-synthetic-analogues-as-inhibitors-of-the-voltage-gated-potassium-channels
#1
Nace Zidar, Aleš Žula, Tihomir Tomašič, Marc Rogers, Robert W Kirby, Jan Tytgat, Steve Peigneur, Danijel Kikelj, Janez Ilaš, Lucija Peterlin Mašič
We have prepared three alkaloids from the Agelas sponges, clathrodin, hymenidin and oroidin, and a series of their synthetic analogues, and evaluated their inhibitory effect against six isoforms of the Kv1 subfamily of voltage-gated potassium channels, Kv1.1-Kv1.6, expressed in Chinese Hamster ovary (CHO) cells using automated patch clamp electrophysiology assay. The most potent inhibitor was the (E)-N-(3-(2-amino-1H-imidazol-4-yl)allyl)-4,5-dichloro-1H-pyrrole-2-carboxamide (6g) with IC50 values between 1...
August 7, 2017: European Journal of Medicinal Chemistry
https://www.readbyqxmd.com/read/28793216/smit1-modifies-kcnq-channel-function-and-pharmacology-by-physical-interaction-with-the-pore
#2
Rían W Manville, Daniel L Neverisky, Geoffrey W Abbott
Voltage-gated potassium channels of the KCNQ (Kv7) subfamily are essential for control of cellular excitability and repolarization in a wide range of cell types. Recently, we and others found that some KCNQ channels functionally and physically interact with sodium-dependent solute transporters, including myo-inositol transporters SMIT1 and SMIT2, potentially facilitating various modes of channel-transporter signal integration. In contrast to indirect effects such as channel regulation by SMIT-transported, myo-inositol-derived phosphatidylinositol 4,5-bisphosphate (PIP2), the mechanisms and functional consequences of the physical interaction of channels with transporters have been little studied...
August 8, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28738160/atrial-selective-k-channel-blockers-potential-antiarrhythmic-drugs-in-atrial-fibrillation
#3
Ursula Ravens
In the wake of demographic change in Western countries atrial fibrillation has reached an epidemiological scale, yet current strategies for drug treatment of the arrhythmia lack sufficient efficacy and safety. In search of novel medications, atrial-selective drugs that specifically target atrial over other cardiac functions have been developed. In this lecture, I will address drugs acting on potassium (K+) channels that are either predominantly expressed in atria or possess electrophysiological properties distinct in atria from ventricles...
July 24, 2017: Canadian Journal of Physiology and Pharmacology
https://www.readbyqxmd.com/read/28729840/cardiac-subtype-specific-modeling-of-kv1-5-ion-channel-deficiency-using-human-pluripotent-stem-cells
#4
Maike Marczenke, Ilaria Piccini, Isabella Mengarelli, Jakob Fell, Albrecht Röpke, Guiscard Seebohm, Arie O Verkerk, Boris Greber
The ultrarapid delayed rectifier K(+) current (IKur), mediated by Kv1.5 channels, constitutes a key component of the atrial action potential. Functional mutations in the underlying KCNA5 gene have been shown to cause hereditary forms of atrial fibrillation (AF). Here, we combine targeted genetic engineering with cardiac subtype-specific differentiation of human induced pluripotent stem cells (hiPSCs) to explore the role of Kv1.5 in atrial hiPSC-cardiomyocytes. CRISPR/Cas9-mediated mutagenesis of integration-free hiPSCs was employed to generate a functional KCNA5 knockout...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/28723914/safety-and-pharmacodynamics-of-dalazatide-a-kv1-3-channel-inhibitor-in-the-treatment-of-plaque-psoriasis-a-randomized-phase-1b-trial
#5
Eric J Tarcha, Chelsea M Olsen, Peter Probst, David Peckham, Ernesto J Muñoz-Elías, James G Kruger, Shawn P Iadonato
BACKGROUND: Dalazatide is a specific inhibitor of the Kv1.3 potassium channel. The expression and function of Kv1.3 channels are required for the function of chronically activated memory T cells, which have been shown to be key mediators of autoimmune diseases, including psoriasis. OBJECTIVE: The primary objective was to evaluate the safety of repeat doses of dalazatide in adult patients with mild-to-moderate plaque psoriasis. Secondary objectives were to evaluate clinical proof of concept and the effects of dalazatide on mediators of inflammation in the blood and on chronically activated memory T cell populations...
2017: PloS One
https://www.readbyqxmd.com/read/28710444/ergodicity-breaking-on-the-neuronal-surface-emerges-from-random-switching-between-diffusive-states
#6
Aleksander Weron, Krzysztof Burnecki, Elizabeth J Akin, Laura Solé, Michał Balcerek, Michael M Tamkun, Diego Krapf
Stochastic motion on the surface of living cells is critical to promote molecular encounters that are necessary for multiple cellular processes. Often the complexity of the cell membranes leads to anomalous diffusion, which under certain conditions it is accompanied by non-ergodic dynamics. Here, we unravel two manifestations of ergodicity breaking in the dynamics of membrane proteins in the somatic surface of hippocampal neurons. Three different tagged molecules are studied on the surface of the soma: the voltage-gated potassium and sodium channels Kv1...
July 14, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28655649/interregional-electro-mechanical-heterogeneity-in-the-rabbit-myocardium
#7
REVIEW
Franz F Dressler, Ilona Bodi, Marius Menza, Robin Moss, Heiko Bugger, Christoph Bode, Jan C Behrends, Gunnar Seemann, Katja E Odening
BACKGROUND: Increased electrical heterogeneity has been causatively linked to arrhythmic disorders, yet the knowledge about physiological heterogeneity remains incomplete. This study investigates regional electro-mechanical heterogeneities in rabbits, one of the key animal models for arrhythmic disorders. METHODS AND FINDINGS: 7 wild-type rabbits were examined by phase-contrast magnetic resonance imaging in vivo to assess cardiac wall movement velocities. Using a novel data-processing algorithm regional contraction-like profiles were calculated...
June 24, 2017: Progress in Biophysics and Molecular Biology
https://www.readbyqxmd.com/read/28552341/methamphetamine-potentiates-hiv-1gp120-induced-microglial-neurotoxic-activity-by-enhancing-microglial-outward-k-current
#8
Jianuo Liu, Enquan Xu, Guihua Tu, Han Liu, Jiangtao Luo, Huangui Xiong
Methamphetamine (Meth) abuse not only increases the risk of human immunodeficiency virus-1 (HIV-1) infection, but exacerbates HIV-1-associated neurocognitive disorders (HAND) as well. The mechanisms underlying the co-morbid effect are not fully understood. Meth and HIV-1 each alone interacts with microglia and microglia express voltage-gated potassium (KV) channel KV1.3. To understand whether KV1.3 functions an intersecting point for Meth and HIV-1, we studied the augment effect of Meth on HIV-1 glycoprotein 120 (gp120)-induced neurotoxic activity in cultured rat microglial cells...
July 2017: Molecular and Cellular Neurosciences
https://www.readbyqxmd.com/read/28549558/the-kv1-3-channel-blocker-vm24-enhances-muscle-glucose-transporter-4-mobilization-but-does-not-reduce-body-weight-gain-in-diet-induced-obese-male-rats
#9
Lorraine Jaimes-Hoy, Georgina B Gurrola, Miguel Cisneros, Patricia Joseph-Bravo, Lourival D Possani, Jean-Louis Charli
AIMS: Voltage-gated potassium channels 1.3 (Kv1.3) can be targeted to reduce diet-induced obesity and insulin resistance in mice. Since species-specific differences in Kv1.3 expression and pharmacology have been observed, we tested the effect of Vm24, a high-affinity specific blocker of Kv1.3 channels from Vaejovis mexicanus smithi, on body weight (BW), glucose tolerance and insulin resistance in diet-induced obese rats. MATERIALS AND METHODS: Young adult male Wistar rats were switched to a high-fat/high-fructose (HFF) diet...
May 23, 2017: Life Sciences
https://www.readbyqxmd.com/read/28502629/the-inhibitory-effects-of-levo-tetrahydropalmatine-on-rat-kv1-5-channels-expressed-in-hek293-cells
#10
Kai Li, Ming-Shan Pi, Xian-Tao Li
Levo-tetrahydropalmatine (l-THP) exerts various pharmacological effects on neural and cardiac tissues and K(+) channel can be one of its multiple targets. The rapidly activating Kv1.5 channel is expressed in a variety of tissues including atrial cells and hippocampal neurons, and has an essential role in tuning the action potential and excitability in those cells. The aim of current study is to explore whether there are the possible effects of l-THP on Kv1.5 channels expressed in HEK293 cells. Superfusion of l-THP led to a dose-dependent blockage of Kv1...
May 11, 2017: European Journal of Pharmacology
https://www.readbyqxmd.com/read/28432329/affinity-biosensors-using-recombinant-native-membrane-proteins-displayed-on-exosomes-application-to-botulinum-neurotoxin-b-receptor
#11
Richard Desplantes, Christian Lévêque, Benjamin Muller, Manuela Lotierzo, Géraldine Ferracci, Michel Popoff, Michael Seagar, Robert Mamoun, Oussama El Far
The development of simple molecular assays with membrane protein receptors in a native conformation still represents a challenging task. Exosomes are extracellular vesicles which, due to their stability and small size, are suited for analysis in various assay formats. Here, we describe a novel approach to sort recombinant fully native and functional membrane proteins to exosomes using a targeting peptide. Specific binding of high affinity ligands to the potassium channel Kv1.2, the G-protein coupled receptor CXCR4, and the botulinum neurotoxin type B (BoNT/B) receptor, indicated their correct assembly and outside out orientation in exosomes...
April 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28391996/molecular-mechanisms-underlying-pimaric-acid-induced-modulation-of-voltage-gated-k-channels
#12
Kazuho Sakamoto, Yoshiaki Suzuki, Hisao Yamamura, Susumu Ohya, Katsuhiko Muraki, Yuji Imaizumi
Voltage-gated K(+) (KV) channels, which control firing and shape of action potentials in excitable cells, are supposed to be potential therapeutic targets in many types of diseases. Pimaric acid (PiMA) is a unique opener of large conductance Ca(2+)-activated K(+) channel. Here, we report that PiMA modulates recombinant rodent KV channel activity. The enhancement was significant at low potentials (<0 mV) but not at more positive potentials. Application of PiMA significantly shifted the voltage-activation relationships (V1/2) of rodent KV1...
April 2017: Journal of Pharmacological Sciences
https://www.readbyqxmd.com/read/28300672/discovery-of-three-toxin-peptides-with-kv1-3-channel-and-il-2-cytokine-inhibiting-activities-from-non-buthidae-scorpions-chaerilus-tricostatus-and-chaerilus-tryznai
#13
Li Ding, Jing Chen, Jinbo Hao, Jiahui Zhang, Xuejun Huang, Fangfang Hu, Zheng Wu, Yaru Liu, Wenxin Li, Zhijian Cao, Yingliang Wu, Jian Li, Shan Li, Hongyan Liu, Wenlong Wu, Zongyun Chen
Non-Buthidae venomous scorpions are huge natural sources of toxin peptides; however, only a few studies have been done to understand their toxin peptides. Herein, we describe three new potential immunomodulating toxin peptides, Ctri18, Ctry68 and Ctry2908, from two non-Buthidae scorpions, Chaerilus tricostatus and Chaerilus tryznai. Sequence alignment analyses showed that Ctri18, Ctry68 and Ctry2908 are three new members of the scorpion toxin α-KTx15 subfamily. Electrophysiological experiments showed that Ctri18, Ctry68 and Ctry2908 blocked the Kv1...
May 2017: Peptides
https://www.readbyqxmd.com/read/28270595/differential-responses-of-rabbit-ventricular-and-atrial-transient-outward-current-ito-to-the-ito-modulator-ns5806
#14
Hongwei Cheng, Mark B Cannell, Jules C Hancox
Transient outward potassium current (Ito) in the heart underlies phase 1 repolarization of cardiac action potentials and thereby affects excitation-contraction coupling. Small molecule activators of Ito may therefore offer novel treatments for cardiac dysfunction, including heart failure and atrial fibrillation. NS5806 has been identified as a prototypic activator of canine Ito This study investigated, for the first time, actions of NS5806 on rabbit atrial and ventricular Ito Whole cell patch-clamp recordings of Ito and action potentials were made at physiological temperature from rabbit ventricular and atrial myocytes...
March 2017: Physiological Reports
https://www.readbyqxmd.com/read/28243504/aminopyridines-for-the-treatment-of-neurologic-disorders
#15
REVIEW
Michael Strupp, Julian Teufel, Andreas Zwergal, Roman Schniepp, Kamran Khodakhah, Katharina Feil
PURPOSE OF REVIEW: To identify the different indications for the treatment of neurologic disorders with the potassium channel blockers 4-aminopyridine (4-AP) and 3,4-diaminopyridine (3,4-DAP). RECENT FINDINGS: 4-AP is an effective symptomatic treatment for downbeat nystagmus (DBN), episodic ataxia type 2 (EA2) (5-10 mg TID), and impaired gait in multiple sclerosis (MS) (10 mg BID). 3,4-DAP (5 mg/d-20 mg TID) improves symptoms in Lambert-Eaton myasthenic syndrome (LEMS) (randomized placebo-controlled trials for all 4 entities)...
February 2017: Neurology. Clinical Practice
https://www.readbyqxmd.com/read/28094801/electronegative-ldl-mediated-cardiac-electrical-remodeling-in-a-rat-model-of-chronic-kidney-disease
#16
An-Sheng Lee, Wei-Yu Chen, Hua-Chen Chan, Ching-Hu Chung, Hsien-Yu Peng, Chia-Ming Chang, Ming-Jai Su, Chu-Huang Chen, Kuan-Cheng Chang
The mechanisms underlying chronic kidney disease (CKD)-associated higher risks for life-threatening ventricular tachyarrhythmias remain poorly understood. In rats subjected to unilateral nephrectomy (UNx), we examined cardiac electrophysiological remodeling and relevant mechanisms predisposing to ventricular arrhythmias. Adult male Sprague-Dawley rats underwent UNx (n = 6) or sham (n = 6) operations. Eight weeks later, the UNx group had higher serum blood urea nitrogen and creatinine levels and a longer electrocardiographic QTc interval than did the sham group...
January 17, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28087137/decreased-expression-of-kv7-channels-in-hirchsprung-s-disease
#17
Anne-Marie O'Donnell, David Coyle, Prem Puri
PURPOSE: Voltage-dependent K(+) channels (Kv channels) participate in electrical rhythmicity and smooth muscle responses and are regulated by excitatory and inhibitory neurotransmitters. Kv channels also participate in the interstitial cell of Cajal (ICC) and smooth muscle cell (SMC) responses to neural inputs. The Kv family consists of 12 subfamilies, Kv1-Kv12, with five members of the Kv7 family identified to date: Kv7.1-Kv7.5. A recent study identified the potassium channel Kv7.5 as having a role in the excitability of ICC-IM in the mouse colon...
July 2017: Journal of Pediatric Surgery
https://www.readbyqxmd.com/read/28054303/amino-acid-properties-of-trafficking-determinants-in-the-outer-pore-forming-region-of-kv1-potassium-channels-in-cell-lines
#18
Barbara Gomez, Jing Zhu, Esperanza Recio-Pinto, William B Thornhill
Different classes of Kv1 potassium channels have different trafficking patterns despite having very similar amino acid sequences. Two amino acids responsible for these differences have been identified in the outer pore turret region of Kv1.1 and Kv1.4. Here we tested a series of substitutions at these two determinants on Kv1.4. All P506 substitutions tested resulted in a significant decrease in surface protein, total protein, and protein half-life, indicating that proline is required at 506 to stabilize protein conformation and increase trafficking to the cell surface...
March 2017: Cell Biochemistry and Biophysics
https://www.readbyqxmd.com/read/28011270/h2s-inhibits-angiotensin-ii-induced-atrial-kv1-5-upregulation-by-attenuating-nox4-mediated-ros-generation-during-atrial-fibrillation
#19
Guihua Lu, Chenggui Xu, Kaiyu Tang, Juhong Zhang, Qinglang Li, Longyun Peng, Yesong Wang, Zhibin Huang, Xiuren Gao
Our previous study demonstrated that angiotensin II (Ang II) upregulates the expression of Kv1.5, a promising target for atrial fibrillation (AF) therapy, by activating ROS-dependent P-Smad2/3 and P-ERK 1/2. A recent study showed that hydrogen sulfide (H2S) may modulate the effects of angiotensin II (Ang II) by inhibiting the NADPH oxidase 4 (Nox4)-ROS signaling in the heart. The present study aimed to determine whether H2S is involved in the regulation of atrial Kv1.5 via ROS-related mechanisms in AF. Cultured neonatal rat atrial myocytes and a beagle model of AF were used for this study...
January 29, 2017: Biochemical and Biophysical Research Communications
https://www.readbyqxmd.com/read/27958660/angiotensin-ii-reduces-the-surface-abundance-of-kv-1-5-channels-in-arterial-myocytes-to-stimulate-vasoconstriction
#20
Michael W Kidd, Simon Bulley, Jonathan H Jaggar
KEY POINTS: Several different voltage-dependent K(+) (KV ) channel isoforms are expressed in arterial smooth muscle cells (myocytes). Vasoconstrictors inhibit KV currents, but the isoform selectivity and mechanisms involved are unclear. We show that angiotensin II (Ang II), a vasoconstrictor, stimulates degradation of KV 1.5, but not KV 2.1, channels through a protein kinase C- and lysosome-dependent mechanism, reducing abundance at the surface of mesenteric artery myocytes. The Ang II-induced decrease in cell surface KV 1...
March 1, 2017: Journal of Physiology
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