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https://www.readbyqxmd.com/read/28646025/remodeling-of-repolarization-and-arrhythmia-susceptibility-in-a-myosin-binding-protein-c-knockout-mouse-model
#1
Amir Toib, Chen Zhang, Giulia Borghetti, Xiaoxiao Zhang, Markus Wallner, Yijun Yang, Constantine Troupes, Hajime Kubo, Thomas Sharp, Eric Feldsott, Remus M Berretta, Neil Zalavadia, Danielle Trappanese, Shavonn Harper, Polina Gross, Xiongwen Chen, Sadia Mohsin, Steven Houser
Hypertrophic cardiomyopathy (HCM) is one of the most common genetic cardiac diseases and amongst the leading causes of sudden cardiac death (SCD) in the young. The cellular mechanisms leading to SCD in HCM are not well known. Prolongation of the action potential duration (APD) is a common feature predisposing hypertrophied hearts to SCD. Previous studies have explored the roles of inward Na(+) and Ca(2+) in the development of HCM, but the role of repolarizing K(+) currents have not been defined. The objective of this study was to characterize the arrhythmogenic phenotype and cellular electrophysiological properties of mice with HCM, induced by Myosin Binding Protein C (MyBPC) Knockout (KO) and to test the hypothesis that remodeling of repolarizing K(+) currents cause APD prolongation in MyBPC KO myocytes...
June 23, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28639215/regulation-of-t-type-ca-2-channel-expression-by-herpes-simplex-virus-1-infection-in-sensory-like-nd7-cells
#2
Qiaojuan Zhang, Shao-Chung Hsia, Miguel Martin-Caraballo
Infection of sensory neurons by herpes simplex virus (HSV)-1 disrupts electrical excitability, altering pain sensory transmission. Because of their low threshold for activation, functional expression of T-type Ca(2+) channels regulates various cell functions, including neuronal excitability and neuronal communication. In this study, we have tested the effect of HSV-1 infection on the functional expression of T-type Ca(2+) channels in differentiated ND7-23 sensory-like neurons. Voltage-gated Ca(2+) currents were measured using whole cell patch clamp recordings in differentiated ND7-23 neurons under various culture conditions...
June 21, 2017: Journal of Neurovirology
https://www.readbyqxmd.com/read/28638923/-reconstitution-of-large-conductance-calcium-activated-potassium-channels-into-artificial-planar-lipid-bilayers
#3
Jun Cheng, Xiao-Rong Zeng, Xiao-Qiu Tan, Peng-Yun Li, Jing Wen, Liang Mao, Yan Yang
This study was aimed to establish a method to create a stable planar lipid bilayer membranes (PLBMs), in which large conductance calcium-activated potassium channels (BKCa) were reconstituted. Using spreading method, PLBMs were prepared by decane lipid fluid consisting of N2-weathered mixture of phosphatidylcholine and cholesterol at 3:1 ratio. After successful incorporation of BKCa channel into PLBMs, single channel characteristics of BKCa were studied by patch clamp method. The results showed that i) the single channel conductance of BKCa was (206...
June 25, 2017: Sheng Li Xue Bao: [Acta Physiologica Sinica]
https://www.readbyqxmd.com/read/28634442/mild-traumatic-brain-injury-evokes-pyramidal-neuron-axon-initial-segment-plasticity-and-diffuse-presynaptic-inhibitory-terminal-loss
#4
Michal Vascak, Jianli Sun, Matthew Baer, Kimberle M Jacobs, John T Povlishock
The axon initial segment (AIS) is the site of action potential (AP) initiation, thus a crucial regulator of neuronal activity. In excitatory pyramidal neurons, the high density of voltage-gated sodium channels (NaV1.6) at the distal AIS regulates AP initiation. A surrogate AIS marker, ankyrin-G (ankG) is a structural protein regulating neuronal functional via clustering voltage-gated ion channels. In neuronal circuits, changes in presynaptic input can alter postsynaptic output via AIS structural-functional plasticity...
2017: Frontiers in Cellular Neuroscience
https://www.readbyqxmd.com/read/28631948/possible-contribution-of-pannexin-1-to-capsaicin-induced-atp-release-in-rat-nasal-columnar-epithelial-cells
#5
Toyoaki Ohbuchi, Ba Hung Do, Hiroki Koizumi, Shoko Takeuchi, Yoichi Ueta, Hideaki Suzuki
Current evidence indicates that transient receptor potential (TRP) channel activity involves a relationship between opening of pannexin-1 and release of ATP into the extracellular space. We examined the effects of agonists of thermosensitive TRP channels (TRPM8, TRPA1, TRPV1, and TRPV2) on ATP release from rat nasal mucosa, and measured ciliary beat frequency (CBF) using digital high-speed video imaging. Single-cell patch clamping from dissociated rat nasal columnar epithelial cells was performed to confirm the relationship between pannexin-1 and TRP...
February 10, 2017: Channels
https://www.readbyqxmd.com/read/28630041/dysregulated-zn-2-homeostasis-impairs-cardiac-type-2-ryanodine-receptor-and-mitsugumin-23-functions-leading-to-sarcoplasmic-reticulum-ca-2-leakage
#6
Benedict Reilly-O'Donnell, Gavin B Robertson, Angela Karumbi, Connor McIntyre, Wojciech Bal, Miyuki Nishi, Hiroshi Takeshima, Alan J Stewart, Samantha J Pitt
Aberrant Zn2+-homeostasis is associated with dysregulated intracellular Ca2+ release resulting in chronic heart failure. In the failing heart, a small population of cardiac ryanodine receptors (RyR2) display sub-conductance state gating leading to Ca2+ leakage from sarcoplasmic reticulum (SR) stores, which impairs cardiac contractility. Previous evidence suggests contribution of RyR2-independent Ca2+ leakage through an uncharacterized mechanism. We sought to examine the role of Zn2+ in shaping intracellular Ca2+ release in cardiac muscle...
June 19, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28628890/interleukin-6-induced-activation-of-a-non-selective-outward-cation-conductance-in-human-cardiac-fibroblasts
#7
Vadim Mitrokhin, Viktor Kazanski, Vladimir Kalsin, Mitko Mladenov, Andre Kamkin
BACKGROUND: It has been demonstrated that cardiac fibroblasts of the human heart have several myocyte-like features, induced by inflammation. OBJECTIVES: This study analyzed the changes of the expressed currents in the basal condition and in the presence of interleukin-6 in cultured human cardiac fibroblasts. METHODS: Human cardiac fibroblasts were cultured as monolayers from earlier passages (2-4). Whole-cell voltage clamp experiments were performed on single culture human cardiac fibroblasts...
June 16, 2017: Cytokine
https://www.readbyqxmd.com/read/28626074/a-type-potassium-channels-contribute-to-prorenin-increase-of-firing-activity-in-hypothalamic-vasopressin-neurosecretory-neurons
#8
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
#9
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/28620187/discovery-and-identification-of-o-o-diethyl-o-4-5-phenyl-4-5-dihydroisoxazol-3-yl-phenyl-phosphorothioate-xp-1408-as-a-novel-mode-of-action-of-organophosphorus-insecticides
#10
Zhigang Zeng, Ying Yan, Bingfeng Wang, Niu Liu, Hanhong Xu
Organophosphorus (OP) insecticides play an important role in pest control. Many OP insecticides have been removed from the market because of their high toxicity to humans. We designed and synthesized a new OP insecticide with the goal of providing a low cost, and less toxic insecticide. The mode of action of O, O-diethyl O-(4-(5-phenyl-4, 5-dihydroisoxazol-3-yl) phenyl) phosphorothioate (XP-1408) was studied in Drosophila melanogaster. Bioassays showed that XP-1408 at a concentration of 50 mg/L delayed larval development...
June 15, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28620120/ethyl-vanillin-activates-trpa1
#11
Shaw-Wen Wu, Daniel K Fowler, Forrest J Shaffer, Jonathon E M Lindberg, James Henry Peters
The non-selective cation channel TRPA1 is expressed in neurons of dorsal root ganglia and trigeminal ganglia and also in vagal afferent neurons that innervate the lungs and gastrointestinal tract. Many TRPA1 agonists are also reactive electrophilic compounds which form covalent adducts with TRPA1. Allyl isothiocyanate (AITC), the common reference agonist used to identify TRPA1, contains a reactive electrophilic group that covalently binds with cysteine residues of TRPA1 and confers a structural change on the channel...
June 15, 2017: Journal of Pharmacology and Experimental Therapeutics
https://www.readbyqxmd.com/read/28619748/pore-polarity-and-charge-determine-differential-block-of-kir1-1-and-kir7-1-potassium-channels-by-the-small-molecule-inhibitor-vu590
#12
Sujay Kharade, Jonathan Sheehan, Eric Figueroa, Jens Meiler, Jerod Denton
VU590 was the first publicly disclosed, sub-micromolar-affinity (IC50=0.2 µM), small-molecule inhibitor of the inward rectifier potassium (Kir) channel, Kir1.1, an emerging diuretic target for the treatment of hypertension. VU590 also inhibits Kir7.1, albeit with 40-fold lower potency (IC50~8 µM), and has been used as a Kir7.1 tool compound to uncover new roles of the channel in regulation of myometrial contractility and melanocortin signaling in the brain. Here, we employed molecular modeling, site-directed mutagenesis, and patch clamp electrophysiology to elucidate the molecular mechanisms underlying inhibition of Kir1...
June 15, 2017: Molecular Pharmacology
https://www.readbyqxmd.com/read/28617952/systolic-ca-2-i-regulates-diastolic-levels-in-rat-ventricular-myocytes
#13
R Sankaranarayanan, K Kistamas, D J Greensmith, L A Venetucci, D A Eisner
[Ca(2+) ]i must be low enough in diastole so that the ventricle is relaxed and can refill with blood. Interference with this will impair relaxation. The factors responsible for regulation of diastolic [Ca(2+) ]i , in particular the relative roles of the sarcoplasmic reticulum (SR) and surface membrane are unclear. We investigated the effects on diastolic [Ca(2+) ]i that result from the changes of Ca cycling known to occur in heart failure. Experiments were performed using Fluo-3 in voltage-clamped rat ventricular myocytes...
June 15, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28616863/contrasting-effects-of-phosphatidylinositol-4-5-bisphosphate-pip2-on-cloned-tmem16a-and-tmem16b-channels
#14
Chau M Ta, Kathryn E Acheson, Nils J G Rorsman, Remco C Jongkind, Paolo Tammaro
BACKGROUND AND PURPOSE: Ca(2+) -activated Cl(-) channels (CaCCs) are gated open by a rise in intracellular Ca(2+) concentration ([Ca(2+) ]i ), typically provoked by Gq -protein coupled receptor activation (Gq PCR). Gq PCR activation initiates depletion of plasmalemmal phosphatidylinositol 4,5-bisphosphate (PIP2 ). Here we ask whether PIP2 acts as a signalling lipid for CaCCs coded by the TMEM16A and TMEM16B genes. EXPERIMENTAL APPROACH: Patch-clamp electrophysiology, in conjunction with genetically-encoded systems to control cellular PIP2 content, was used to define the mechanism of action of PIP2 on TMEM16A and TMEM16B channels...
June 14, 2017: British Journal of Pharmacology
https://www.readbyqxmd.com/read/28616862/loops-d-e-and-g-in-the-drosophila-d%C3%AE-1-subunit-contribute-to-high-neonicotinoid-sensitivity-of-d%C3%AE-1-chicken-%C3%AE-2-nicotinic-acetylcholine-receptor
#15
Makoto Ihara, Mai Hikida, Hiroyuki Matsushita, Kyosuke Yamanaka, Yuya Kishimoto, Kazuki Kubo, Shun Watanabe, Mifumi Sakamoto, Koutaro Matsui, Akihiro Yamaguchi, Daiki Okuhara, Shogo Furutani, David B Sattelle, Kazuhiko Matsuda
BACKGROUND AND PURPOSE: Neonicotinoid insecticides interact with the orthosteric site formed at subunit interfaces of insect nicotinic acetylcholine receptors (insect nACh receptors). However, their interactions with the orthosteric sites at α-non α and α-α subunit interfaces remain poorly understood. The aim of this study was to elucidate the mechanism of neonicotinoid actions using the Drosophila Dα1-chicken β2 hybrid nACh receptor. EXPERIMENTAL APPROACH: Computer models of the (Dα1)3 (β2)2 nACh receptor in complex with imidacloprid and thiacloprid were generated...
June 14, 2017: British Journal of Pharmacology
https://www.readbyqxmd.com/read/28612144/fast-calcium-transients-translate-the-distribution-and-conduction-of-neural-activity-in-different-regions-of-a-single-sensory-neuron
#16
Nuhan Purali
In the present study, cytosolic calcium concentration changes were recorded in response to various forms of excitations, using the fluorescent calcium indicator dye OG-BAPTA1 together with the current or voltage clamp methods in stretch receptor neurons of crayfish. A single action potential evoked a rise in the resting calcium level in the axon and axonal hillock, whereas an impulse train or a large saturating current injection would be required to evoke an equivalent response in the dendrite region. Under voltage clamp conditions, amplitude differences between axon and dendrite responses vanished completely...
September 2017: Invertebrate Neuroscience: IN
https://www.readbyqxmd.com/read/28611679/icariin-a-novel-blocker-of-sodium-and-calcium-channels-eliminates-early-and-delayed-afterdepolarizations-as-well-as-triggered-activity-in-rabbit-cardiomyocytes
#17
Wanzhen Jiang, Mengliu Zeng, Zhenzhen Cao, Zhipei Liu, Jie Hao, Peipei Zhang, Youjia Tian, Peihua Zhang, Jihua Ma
Icariin, a flavonoid monomer from Herba Epimedii, has confirmed pharmacological and biological effects. However, its effects on arrhythmias and cardiac electrophysiology remain unclear. Here we investigate the effects of icariin on ion currents and action potentials (APs) in the rabbit myocardium. Furthermore, the effects of icariin on aconitine-induced arrhythmias were assessed in whole rabbits. Ion currents and APs were recorded in voltage-clamp and current-clamp mode in rabbit left ventricular myocytes (LVMs) and left atrial myocytes (LAMs), respectively...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/28608537/inhibition-of-human-n-and-t-type-calcium-channels-by-an-ortho-phenoxyanilide-derivative-moniro-1
#18
Jeffrey R McArthur, Leonid Motin, Ellen C Gleeson, Sandro Spiller, Richard J Lewis, Peter J Duggan, Kellie L Tuck, David J Adams
BACKGROUND AND PURPOSE: Voltage-gated calcium channels are involved in peripheral and central nervous system nociception. N-type (Cav 2.2) and T-type (Cav 3.1, Cav 3.2 and Cav 3.3) voltage-gated calcium channels are particularly important in studying and treating pain and epilepsy. EXPERIMENTAL APPROACH: In this study, whole-cell patch clamp electrophysiology was used to assess the potency and mechanism of action of a novel ortho-phenoxylanilide derivative, MONIRO-1, against a panel of voltage-gated calcium channels including Cav 1...
June 13, 2017: British Journal of Pharmacology
https://www.readbyqxmd.com/read/28605379/voltage-clamp-fluorometry-in-xenopus-oocytes-using-fluorescent-unnatural-amino-acids
#19
Tanja Kalstrup, Rikard Blunck
Voltage-Clamp Fluorometry (VCF) has been the technique of choice to investigate the structure and function of electrogenic membrane proteins where real-time measurements of fluorescence and currents simultaneously report on local rearrangements and global function, respectively(1). While high-resolution structural techniques such as cryo-electron microscopy or X-ray crystallography provide static images of the proteins of interest, VCF provides dynamic structural data that allows us to link the structural rearrangements (fluorescence) to dynamic functional data (electrophysiology)...
May 27, 2017: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/28603015/activation-of-a-ca-2-dependent-cation-conductance-with-properties-of-trpm2-by-reactive-oxygen-species-in-lens-epithelial-cells
#20
Susanne Keckeis, Laura Wernecke, Daniel J Salchow, Nadine Reichhart, Olaf Strauß
Ion channels are crucial for maintenance of ion homeostasis and transparency of the lens. The lens epithelium is the metabolically and electrophysiologically active cell type providing nutrients, ions and water to the lens fiber cells. Ca(2+)-dependent non-selective ion channels seem to play an important role for ion homeostasis. The aim of the study was to identify and characterize Ca(2+)- and reactive oxygen species (ROS)-dependent non-selective cation channels in human lens epithelial cells. RT-PCR revealed gene expression of the Ca(2+)-activated non-selective cation channels TRPC3, TRPM2, TRPM4 and Ano6 in both primary lens epithelial cells and the cell line HLE-B3, whereas TRPM5 mRNA was only found in HLE-B3 cells...
June 8, 2017: Experimental Eye Research
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