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https://www.readbyqxmd.com/read/28648120/long-qt-syndrome-associated-caveolin-3-mutations-differentially-regulate-the-hyperpolarization-activated-cyclic-nucleotide-gated-channel-4
#1
L J Motloch, R Larbig, T Darabi, S Reda, K A Motloch, B Wernly, M Lichtenauer, T Gebing, A Schwaiger, N Zagidullin, M Wolny, U C Hoppe
Background Caveolin-3 (cav-3) mutations are linked to the long-QT syndrome (LQTS) causing distinct clinical symptoms. Hyperpolarization-activated cyclic nucleotide channel 4 (HCN4) underlies the pacemaker current If. It associates with cav-3 and both form a macromolecular complex. Methods To examine the effects of human LQTS-associated cav-3 mutations on HCN4-channel function, HEK293-cells were cotransfected with HCN4 and wild-type (WT) cav-3 or a LQTS-associated cav-3 mutant (T78M, A85T, S141R, or F97C). HCN4 currents were recorded using the whole-cell patch-clamp technique...
June 26, 2017: Physiology International
https://www.readbyqxmd.com/read/28646166/atp-release-during-cell-swelling-activates-a-ca-2-dependent-cl-current-by-autocrine-mechanism-in-mouse-hippocampal-microglia
#2
E Murana, F Pagani, B Basilico, M Sundukova, L Batti, S Di Angelantonio, B Cortese, A Grimaldi, A Francioso, P Heppenstall, P Bregestovski, C Limatola, D Ragozzino
Microglia cells, resident immune cells of the brain, survey brain parenchyma by dynamically extending and retracting their processes. Cl(-) channels, activated in the cellular response to stretch/swelling, take part in several functions deeply connected with microglia physiology, including cell shape changes, proliferation, differentiation and migration. However, the molecular identity and functional properties of these Cl(-) channels are largely unknown. We investigated the properties of swelling-activated currents in microglial from acute hippocampal slices of Cx3cr1 (+/GFP) mice by whole-cell patch-clamp and imaging techniques...
June 23, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28644055/regulation-of-transient-receptor-potential-melastatin-4-channel-by-sarcoplasmic-reticulum-inositol-triphosphate-receptors-role-in-human-detrusor-smooth-muscle-function
#3
Aaron Provence, Eric S Rovner, Georgi V Petkov
We recently reported key physiological roles for Ca(2+)-activated transient receptor potential melastatin 4 (TRPM4) channels in detrusor smooth muscle (DSM). However, the Ca(2+)-signaling mechanisms governing TRPM4 channel activity in human DSM cells are unexplored. As the TRPM4 channels are activated by Ca(2+), inositol 1,4,5-trisphosphate receptor (IP3R)-mediated Ca(2+) release from the sarcoplasmic reticulum represents a potential Ca(2+) source for TRPM4 channel activation. We used clinically-characterized human DSM tissues to investigate the molecular and functional interactions of the IP3Rs and TRPM4 channels...
June 23, 2017: Channels
https://www.readbyqxmd.com/read/28642282/kappa-opioid-receptors-mediate-heterosynaptic-suppression-of-hippocampal-inputs-in-the-rat-ventral-striatum
#4
Julie Brooks, Patricio O'Donnell
Kappa opioid receptors (KOR) are highly enriched within the ventral striatum (VS) and are thought to modulate striatal neurotransmission. This includes presynaptic inhibition of local glutamatergic release from excitatory inputs to the VS. However, it is not known which inputs drive this modulation and what impact they have on the local circuit dynamics within the VS. Individual medium spiny neurons (MSNs) within the VS serve as a site of convergence for glutamatergic inputs arising from the prefrontal cortex (PFC) and limbic regions, such as the hippocampus (HP)...
June 22, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28642232/a-single-amino-acid-residue-at-transmembrane-domain-4-of-the-alpha-subunit-influences-carisoprodol-direct-gating-efficacy-at-gabaa-receptors
#5
Manoj Kumar, Manish Kumar, John Freund, Glenn H Dillon
The muscle relaxant carisoprodol (CSP, trade name Soma) has recently been controlled at the federal level as a Schedule IV drug due to its high abuse potential and consequences of misuse, such as withdrawal syndrome, delusions, seizures and even death. Recent work has shown that carisoprodol can directly gate and allosterically modulate the GABAA receptor. These actions are subunit-dependent; compared to other GABAA receptors, carisoprodol has nominal direct gating effects in α3β2γ2receptors. Here, using site-directed-mutagenesis and whole cell patch clamp electrophysiology in transiently transfected HEK293 cells, we examined the role of GABAA receptor α subunit transmembrane domain 4 (TM4) amino acids in direct gating and allosteric modulatory actions of carisoprodol...
June 22, 2017: Journal of Pharmacology and Experimental Therapeutics
https://www.readbyqxmd.com/read/28641963/modulation-of-the-heart-s-electrical-properties-by-the-anticonvulsant-drug-retigabine
#6
Lena Rubi, Michael Kovar, Eva Zebedin-Brandl, Xaver Koenig, Manuel Dominguez-Rodriguez, Hannes Todt, Helmut Kubista, Stefan Boehm, Karlheinz Hilber
Retigabine, currently used as antiepileptic drug, has a wide range of potential medical uses. Administration of the drug in patients can lead to QT interval prolongation in the electrocardiogram and to cardiac arrhythmias in rare cases. This suggests that the drug may perturb the electrical properties of the heart, and the underlying mechanisms were investigated here. Effects of retigabine on currents through human cardiac ion channels, heterologously expressed in tsA-201 cells, were studied in whole-cell patch-clamp experiments...
June 19, 2017: Toxicology and Applied Pharmacology
https://www.readbyqxmd.com/read/28640864/targeting-breast-cancer-cells-by-mrs1477-a-positive-allosteric-modulator-of-trpv1-channels
#7
Mustafa Nazıroğlu, Bilal Çiğ, Walter Blum, Csaba Vizler, Andrea Buhala, Annamária Marton, Róbert Katona, Katalin Jósvay, Beat Schwaller, Zoltán Oláh, László Pecze
There is convincing epidemiological and experimental evidence that capsaicin, a potent natural transient receptor potential cation channel vanilloid member 1 (TRPV1) agonist, has anticancer activity. However, capsaicin cannot be given systemically in large doses, because of its induction of acute pain and neurological inflammation. MRS1477, a dihydropyridine derivative acts as a positive allosteric modulator of TRPV1, if added together with capsaicin, but is ineffective, if given alone. Addition of MRS1477 evoked Ca2+ signals in MCF7 breast cancer cells, but not in primary breast epithelial cells...
2017: PloS One
https://www.readbyqxmd.com/read/28640508/intraglomerular-gap-junctions-enhance-interglomerular-synchrony-in-a-sparsely-connected-olfactory-bulb-network
#8
Frederic Pouille, Thomas S McTavish, Lawrence E Hunter, Diego Restrepo, Nathan E Schoppa
A dominant feature of the olfactory bulb response to odour is fast synchronized oscillations at beta (15-40 Hz) or gamma (40-90 Hz) frequencies, thought to be involved in integration of olfactory signals. Mechanistically, the bulb presents an interesting case study for understanding how beta/gamma oscillations arise. Fast oscillatory synchrony in the activity of output mitral cells (MCs) appears to result from interactions with GABAergic granule cells (GCs), yet the incidence of MC-GC connections is very low, around 4%...
June 22, 2017: Journal of 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
#9
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
#10
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/28637949/comparative-analysis-of-allyl-isothiocyanate-aitc-induced-carbohydrate-oxidation-changes-via-trpv1-between-mice-and-chickens
#11
Fuminori Kawabata, Yuko Kawabata, Ruojun Liang, Shotaro Nishimura, Shoji Tabata
Postprandial hyperglycemia is a risk factor for cardiovascular diseases. It has been reported that intragastric administration of allyl isothiocyanate (AITC), which is one of the pungent ingredients of wasabi and horseradish but it is not included in hot chili pepper, increased carbohydrate oxidation and reduced postprandial increase of blood glucose via transient receptor potential vanilloid 1 (TRPV1)in mice. However, the action site of AITC on TRPV1 for increasing carbohydrate oxidation is unclear. Both mammalian and chicken TRPV1 (cTRPV1) are activated by heat and acid, but unlike its mammalian counterpart, cTRPV1 is only faintly activated by capsaicin...
2017: Biomedical Research
https://www.readbyqxmd.com/read/28637815/the-pro-inflammatory-cytokine-tumor-necrosis-factor-alpha-excites-subfornical-organ-neurons
#12
Nick James Simpson, Alastair V Ferguson
Tumor necrosis factor alpha (TNFα) is a pro-inflammatory cytokine implicated in cardiovascular and autonomic regulation via actions in the central nervous system. TNFα(-/-) mice do not develop angiotensin II (ANG II)-induced hypertension, and administration of TNFα into the bloodstream of rats increases blood pressure and sympathetic tone. Recent studies have shown that lesion of the subfornical organ (SFO) attenuates the hypertensive and autonomic effects of TNFα, while direct administration of TNFα into the SFO increases blood pressure, suggesting the SFO to be a key site for the actions of TNFα...
June 21, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/28637786/the-role-of-capsaicin-sensitive-c-fiber-afferent-pathways-in-the-control-of-micturition-in-spinal-intact-and-spinal-cord-injured-mice
#13
Katsumi Kadekawa, Tsuyoshi Majima, Takahiro Shimizu, Naoki Wada, William C de Groat, Anthony J Kanai, Momokazu Goto, Mitsuharu Yoshiyama, Kimio Sugaya, Naoki Yoshimura
We examined bladder and urethral sphincter activity in mice with or without spinal cord injury (SCI) after C-fiber afferent desensitization induced by capsaicin pretreatment and changes in electrophysiological properties of mouse bladder afferent neurons 4 weeks after SCI. Female C57BL/6N mice were divided into 4 groups; (1) spinal intact (SI)-control, (2) SI-capsaicin pretreatment (Cap), (3) SCI-control and (4) SCI-Cap groups. Continuous cystometry and external urethral sphincter (EUS)-electromyogram (EMG) were conducted under an awake condition...
June 21, 2017: American Journal of Physiology. Renal Physiology
https://www.readbyqxmd.com/read/28637782/the-brugada-syndrome-susceptibility-gene-hey2-modulates-cardiac-transmural-ion-channel-patterning-and-electrical-heterogeneity
#14
Christiaan C Veerman, Svitlana Podliesna, Rafik Tadros, Elisabeth M Lodder, Isabella Mengarelli, Berend de Jonge, Leander Beekman, Julien Barc, Ronald Wilders, Arthur A Wilde, Bastiaan J Boukens, Ruben Coronel, Arie Verkerk, Carol Ann Remme, Connie R Bezzina
Rationale: Genome-wide association studies previously identified an association of rs9388451 at chromosome 6q22.3 (near HEY2) with Brugada syndrome (BrS). The causal gene and underlying mechanism remain unresolved. Objective: We used an integrative approach entailing transcriptomic studies in human hearts and electrophysiological studies in Hey2 heterozygous knockout mice (Hey2(+/-) ) to dissect the underpinnings of the 6q22.31 association with BrS. Methods and Results: We queried expression quantitative trait locus (eQTL) data acquired in 190 human left ventricular (LV) samples from the Genotype-Tissue Expression (GTEx) consortium for cis-eQTL effects of rs9388451 which revealed an association between BrS risk allele dosage and HEY2 expression (β=+0...
June 21, 2017: Circulation Research
https://www.readbyqxmd.com/read/28635080/neuroadaptations-of-presynaptic-and-postsynaptic-gabab-receptor-function-in-the-paraventricular-nucleus-in-response-to-chronic-unpredictable-stress
#15
Yonggang Gao, Jing-Jing Zhou, Yun Zhu, Li Wang, Therese A Kosten, Xiangjian Zhang, De-Pei Li
BACKGROUND: Chronic stress induces an impaired GABAA (γ-aminobutyric acid type A) receptor-mediated inhibition in the hypothalamic paraventricular nucleus (PVN). It is not clear whether GABAB receptor function is altered in chronic stress. We hypothesize that chronic stress alters GABAB receptor function in PVN corticotrophin-releasing hormone (CRH) neurons to control hypothalamus-pituitary-adrenal (HPA) axis activity. EXPERIMENTAL APPROACH: Whole cell patch-clamp recording was performed on PVN-CRH neurons expressing eGFP driven by CRH promoter in brain slices from unstressed rats and rats that had been subjected to chronic unpredictable mild stress (CUMS)...
June 20, 2017: British Journal of Pharmacology
https://www.readbyqxmd.com/read/28634442/mild-traumatic-brain-injury-evokes-pyramidal-neuron-axon-initial-segment-plasticity-and-diffuse-presynaptic-inhibitory-terminal-loss
#16
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/28632132/antagonistic-modulation-of-npy-agrp-and-pomc-neurons-in-the-arcuate-nucleus-by-noradrenalin
#17
Lars Paeger, Ismene Karakasilioti, Janine Altmüller, Peter Frommolt, Jens Brüning, Peter Kloppenburg
In the arcuate nucleus of the hypothalamus (ARH) satiety signaling (anorexigenic) pro-opiomelanocortin (POMC)-expressing and hunger signaling (orexigenic) agouti-related peptide (AgRP)-expressing neurons are key components of the neuronal circuits that control food intake and energy homeostasis. Here, we assessed whether the catecholamine noradrenalin directly modulates the activity of these neurons in mice. Perforated patch clamp recordings showed that noradrenalin changes the activity of these functionally antagonistic neurons in opposite ways, increasing the activity of the orexigenic NPY/AgRP neurons and decreasing the activity of the anorexigenic POMC neurons...
June 20, 2017: ELife
https://www.readbyqxmd.com/read/28631948/possible-contribution-of-pannexin-1-to-capsaicin-induced-atp-release-in-rat-nasal-columnar-epithelial-cells
#18
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/28631579/opening-of-katp-channel-regulates-tonic-currents-from-pyramidal-neurons-in-rat-brain
#19
Zhongxia Li, Jiangping Wang, Huimin Yu, Kewen Jiang
BACKGROUND: ATP-sensitive K+ (KATP) channels couple metabolic state to cellular excitability. Activation of neuronal and astrocytic mitochondrial KATP (mitoKATP) channels regulates a variety of neuronal functions. However, less is known about the impact of mitoKATP on tonic γ-aminobutyric acid (GABA) inhibition. Tonic GABA inhibition is mediated by the binding of ambient GABA on extrasynaptic GABA A-type receptors (GABAARs) and is involved in regulating neuronal excitability. METHODS: We determined the impact of activation of KATP channels with diazoxide (DIZ) on tonic inhibition and recorded tonic current from rat cortical layer 5 pyramidal cells by patch-clamp recordings...
June 20, 2017: Canadian Journal of Neurological Sciences. le Journal Canadien des Sciences Neurologiques
https://www.readbyqxmd.com/read/28628228/epigenetic-mechanisms-underlying-nmda-receptor-hypofunction-in-the-prefrontal-cortex-of-juvenile-animals-in-the-mam-model-for-schizophrenia
#20
Yelena Gulchina, Song-Jun Xu, Melissa A Snyder, Felice Elefant, Wen-Jun Gao
Schizophrenia (SCZ) is characterized not only by psychosis, but also by working memory and executive functioning deficiencies, processes that rely on the prefrontal cortex (PFC). Because these cognitive impairments emerge prior to psychosis onset, we investigated synaptic function during development in the neurodevelopmental methylazoxymethanol acetate (MAM) model for SCZ. Specifically, we hypothesize that NMDAR hypofunction is attributable to reductions in the NR2B subunit through aberrant epigenetic regulation of gene expression, resulting in deficient synaptic physiology and PFC-dependent cognitive dysfunction, a hallmark of SCZ...
June 19, 2017: Journal of Neurochemistry
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