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Kir2.4

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https://www.readbyqxmd.com/read/28301408/k-cl-cotransporter-2-mediated-cl-extrusion-determines-developmental-stage-dependent-impact-of-propofol-anesthesia-on-dendritic-spines
#1
Martin Puskarjov, Hubert Fiumelli, Adrian Briner, Timea Bodogan, Kornel Demeter, Claudia-Marvine Lacoh, Martina Mavrovic, Peter Blaesse, Kai Kaila, Laszlo Vutskits
BACKGROUND: General anesthetics potentiating γ-aminobutyric acid (GABA)-mediated signaling are known to induce a persistent decrement in excitatory synapse number in the cerebral cortex when applied during early postnatal development, while an opposite action is produced at later stages. Here, the authors test the hypothesis that the effect of general anesthetics on synaptogenesis depends upon the efficacy of GABA receptor type A (GABAA)-mediated inhibition controlled by the developmental up-regulation of the potassium-chloride (K-Cl) cotransporter 2 (KCC2)...
March 16, 2017: Anesthesiology
https://www.readbyqxmd.com/read/28289282/the-schizophrenia-and-autism-associated-gene-transcription-factor-4-regulates-the-columnar-distribution-of-layer-2-3-prefrontal-pyramidal-neurons-in-an-activity-dependent-manner
#2
S C Page, G R Hamersky, R A Gallo, M D Rannals, N E Calcaterra, M N Campbell, B Mayfield, A Briley, B N Phan, A E Jaffe, B J Maher
Disruption of the laminar and columnar organization of the brain is implicated in several psychiatric disorders. Here, we show in utero gain-of-function of the psychiatric risk gene transcription factor 4 (TCF4) severely disrupts the columnar organization of medial prefrontal cortex (mPFC) in a transcription- and activity-dependent manner. This morphological phenotype was rescued by co-expression of TCF4 plus calmodulin in a calcium-dependent manner and by dampening neuronal excitability through co-expression of an inwardly rectifying potassium channel (Kir2...
March 14, 2017: Molecular Psychiatry
https://www.readbyqxmd.com/read/28284503/renal-denervation-regulates-the-atrial-arrhythmogenic-substrates-through-reverse-structural-remodeling-in-heart-failure-rabbit-model
#3
Shinya Yamada, Li-Wei Lo, Yu-Hui Chou, Wei-Lun Lin, Shih-Lin Chang, Yenn-Jiang Lin, Shih-Ann Chen
BACKGROUND: Heart failure (HF) causes atrial remodeling and increases the incidence of atrial fibrillation (AF). Renal denervation (RDN) has been shown to decrease the development of AF. This study aimed to identify the effects of RDN on the atrial arrhythmogenic substrates in HF. METHODS: Rabbits were classified into four groups: control (n=9), RDN (n=10), HF (n=6) and HF-RDN (n=9). Surgical and chemical RDN was approached through bilateral retroperitoneal flank incisions in RDN and HF-RDN...
February 24, 2017: International Journal of Cardiology
https://www.readbyqxmd.com/read/28148533/inhibition-of-vascular-smooth-muscle-inward-rectifier-k-channels-restores-myogenic-tone-in-mouse-urinary-bladder-arterioles
#4
Nathan R Tykocki, Adrian D Bonev, Thomas Andrew Longden, Thomas J Heppner, Mark T Nelson
Prolonged decreases in urinary bladder blood flow are linked to overactive and underactive bladder pathologies. However, the mechanisms regulating bladder vascular reactivity are largely unknown. To investigate these mechanisms, we examined myogenic and vasoactive properties of mouse bladder feed arterioles (BFAs). Unlike similar-sized arterioles from other vascular beds, BFAs failed to constrict in response to increases in intraluminal pressure (5-80 mmHg). Consistent with this lack of myogenic tone, arteriolar smooth muscle cell membrane potential was hyperpolarized (-72...
February 1, 2017: American Journal of Physiology. Renal Physiology
https://www.readbyqxmd.com/read/28112313/soluble-epoxide-hydrolase-inhibitors-might-prevent-ischemic-arrhythmias-via-microrna-1-repression-in-primary-neonatal-mouse-ventricular-myocytes
#5
Qiong Liu, Xuan Zhao, Ran Peng, Mi Wang, Wang Zhao, Ya-Jun Gui, Cai-Xiu Liao, Dan-Yan Xu
Ischemic arrhythmias are the main causes of sudden cardiac death. It has been reported that soluble epoxide hydrolase inhibitors (sEHis) could prevent arrhythmias; however, the underlying molecular mechanisms remain unclear. In recent years, the proarrhythmic role of microRNA-1 (miR-1) has been investigated. This study aimed to elucidate whether sEHis prevented ischemic arrhythmias by suppressing miR-1. The primary neonatal mouse ventricular myocyte model of miR-1 overexpression was established by incubating with agonist microONTM mmu-miR-1a-3p agomir (DAEDstain(TM) Dye) (agomiR-1)...
January 23, 2017: Molecular BioSystems
https://www.readbyqxmd.com/read/28007664/effects-of-seasonal-acclimatization-on-action-potentials-and-sarcolemmal-k-currents-in-roach-rutilus-rutilus-cardiac-myocytes
#6
Ahmed Badr, Minna Hassinen, Mohamed F El-Sayed, Matti Vornanen
Temperature sensitivity of electrical excitability is a potential limiting factor for high temperature tolerance of ectotherms. The present study examines whether heat resistance of electrical excitability of cardiac myocytes is modified by seasonal thermal acclimatization in roach (Rutilus rutilus), a eurythermal teleost species. To this end, temperature dependencies of ventricular action potentials (APs), and atrial and ventricular K(+) currents were measured from winter-acclimatized (WiR) and summer-acclimatized (SuR) roach...
March 2017: Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology
https://www.readbyqxmd.com/read/27882143/expression-of-connexin-43-ion-channels-and-ca-2-handling-proteins-in-rat-pulmonary-vein-cardiomyocytes
#7
Yaqiong Xiao, Xue Cai, Andrew Atkinson, Sunil Jit Logantha, Mark Boyett, Halina Dobrzynski
Atrial fibrillation (AF) is the most common cardiac arrhythmia. AF is thought to be triggered by ectopic beats, originating primarily in the myocardial sleeves surrounding the pulmonary veins (PVs). The mechanisms underlying these cardiac arrhythmias remain unclear. To investigate this, frozen sections of heart and lung tissue from adult rats without arrhythmia were obtained in different planes, stained with Masson's trichrome, and immunolabeled for connexin 43 (Cx43), caveolin-3 (Cav3), hyperpolarization-activated cyclic nucleotide-gated channel 4 (HCN4), Nav1...
November 2016: Experimental and Therapeutic Medicine
https://www.readbyqxmd.com/read/27872214/effects-of-prolonged-anoxia-on-electrical-activity-of-the-heart-in-crucian-carp-carassius-carassius
#8
Elisa Tikkanen, Jaakko Haverinen, Stuart Egginton, Minna Hassinen, Matti Vornanen
The effects of sustained anoxia on cardiac electrical excitability were examined in the anoxia-tolerant crucian carp (Carassius carassius). The electrocardiogram (ECG) and expression of excitation-contraction coupling genes were studied in fish acclimatised to normoxia in summer (+18°C) or winter (+2°C), and in winter fish after 1, 3 and 6 weeks of anoxia. Anoxia induced a sustained bradycardia from a heart rate of 10.3±0.77 beats min(-1) to 4.1±0.29 beats min(-1) (P<0.05) after 5 weeks, and heart rate slowly recovered to control levels when oxygen was restored...
February 1, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/27696527/differential-kv1-3-kca3-1-and-kir2-1-expression-in-classically-and-alternatively-activated-microglia
#9
Hai M Nguyen, Eva M Grössinger, Makoto Horiuchi, Kyle W Davis, Lee-Way Jin, Izumi Maezawa, Heike Wulff
Microglia are highly plastic cells that can assume different phenotypes in response to microenvironmental signals. Lipopolysaccharide (LPS) and interferon-γ (IFN-γ) promote differentiation into classically activated M1-like microglia, which produce high levels of pro-inflammatory cytokines and nitric oxide and are thought to contribute to neurological damage in ischemic stroke and Alzheimer's disease. IL-4 in contrast induces a phenotype associated with anti-inflammatory effects and tissue repair. We here investigated whether these microglia subsets vary in their K(+) channel expression by differentiating neonatal mouse microglia into M(LPS) and M(IL-4) microglia and studying their K(+) channel expression by whole-cell patch-clamp, quantitative PCR and immunohistochemistry...
January 2017: Glia
https://www.readbyqxmd.com/read/27527100/structural-basis-of-control-of-inward-rectifier-kir2-channel-gating-by-bulk-anionic-phospholipids
#10
Sun-Joo Lee, Feifei Ren, Eva-Maria Zangerl-Plessl, Sarah Heyman, Anna Stary-Weinzinger, Peng Yuan, Colin G Nichols
Inward rectifier potassium (Kir) channel activity is controlled by plasma membrane lipids. Phosphatidylinositol-4,5-bisphosphate (PIP2) binding to a primary site is required for opening of classic inward rectifier Kir2.1 and Kir2.2 channels, but interaction of bulk anionic phospholipid (PL(-)) with a distinct second site is required for high PIP2 sensitivity. Here we show that introduction of a lipid-partitioning tryptophan at the second site (K62W) generates high PIP2 sensitivity, even in the absence of PL(-) Furthermore, high-resolution x-ray crystal structures of Kir2...
September 2016: Journal of General Physiology
https://www.readbyqxmd.com/read/27511995/effect-of-ethanol-and-acetaldehyde-at-clinically-relevant-concentrations-on-atrial-inward-rectifier-potassium-current-ik1-separate-and-combined-effect
#11
Z Horakova, P Matejovic, M Pasek, J Hosek, M Simurdova, J Simurda, M Bebarova
Atrial fibrillation is the most common arrhythmia at alcohol consumption. Its pathogenesis is complex, at least partly related to changes of cardiac inward rectifier potassium currents including IK1. Both ethanol and acetaldehyde have been demonstrated to considerably modify IK1 in rat ventricular myocytes. However, analogical data on the atrial IK1 are lacking. The present study aimed to analyse IK1 changes induced by ethanol and acetyldehyde in atrial myocytes. The experiments were performed by the whole cell patch-clamp technique at 23 ± 1°C on enzymatically isolated rat and guinea-pig atrial myocytes as well as on expressed human Kir2...
June 2016: Journal of Physiology and Pharmacology: An Official Journal of the Polish Physiological Society
https://www.readbyqxmd.com/read/27235552/hypoxic-stress-up-regulates-kir2-1-expression-and-facilitates-cell-proliferation-in-brain-capillary-endothelial-cells
#12
Hideto Yamamura, Yoshiaki Suzuki, Hisao Yamamura, Kiyofumi Asai, Yuji Imaizumi
The blood-brain barrier (BBB) is mainly composed of brain capillary endothelial cells (BCECs), astrocytes and pericytes. Brain ischemia causes hypoxic encephalopathy and damages BBB. However, it remains still unclear how hypoxia affects BCECs. In the present study, t-BBEC117 cells, an immortalized bovine brain endothelial cell line, were cultured under hypoxic conditions at 4-5% oxygen for 72 h. This hypoxic stress caused hyperpolarization of resting membrane potential. Patch-clamp recordings revealed a marked increase in Ba(2+)-sensitive inward rectifier K(+) current in t-BBEC117 cells after hypoxic culture...
August 5, 2016: Biochemical and Biophysical Research Communications
https://www.readbyqxmd.com/read/27117805/pharmacological-inhibition-of-ik1-by-pa-6-in-isolated-rat-hearts-affects-ventricular-repolarization-and-refractoriness
#13
Mark A Skarsfeldt, Helena Carstensen, Lasse Skibsbye, Chuyi Tang, Rikke Buhl, Bo H Bentzen, Thomas Jespersen
The inwardly rectifying potassium current (IK 1) conducted through Kir2.X channels contribute to repolarization of the cardiac action potential and to stabilization of the resting membrane potential in cardiomyocytes. Our aim was to investigate the effect of the recently discovered IK 1 inhibitor PA-6 on action potential repolarization and refractoriness in isolated rat hearts. Transiently transfected HEK-293 cells expressing IK 1 were voltage-clamped with ramp protocols. Langendorff-perfused heart experiments were performed on male Sprague-Dawley rats, effective refractory period, Wenckebach cycle length, and ventricular effective refractory period were determined following 200 nmol/L PA-6 perfusion...
April 2016: Physiological Reports
https://www.readbyqxmd.com/read/27078635/optical-control-of-a-neuronal-protein-using-a-genetically-encoded-unnatural-amino-acid-in-neurons
#14
Ji-Yong Kang, Daichi Kawaguchi, Lei Wang
Photostimulation is a noninvasive way to control biological events with excellent spatial and temporal resolution. New methods are desired to photo-regulate endogenous proteins expressed in their native environment. Here, we present an approach to optically control the function of a neuronal protein directly in neurons using a genetically encoded unnatural amino acid (Uaa). By using an orthogonal tRNA/aminoacyl-tRNA synthetase pair to suppress the amber codon, a photo-reactive Uaa 4,5-dimethoxy-2-nitrobenzyl-cysteine (Cmn) is site-specifically incorporated in the pore of a neuronal protein Kir2...
March 28, 2016: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/27009332/complex-molecular-and-functional-outcomes-of-single-versus-sequential-cytokine-stimulation-of-rat-microglia
#15
Tamjeed A Siddiqui, Starlee Lively, Lyanne C Schlichter
BACKGROUND: Microglia are the "professional" phagocytes of the CNS. Phagocytosis is crucial for normal CNS development and maintenance, but it can be either beneficial or detrimental after injury or disease. For instance, white matter damage releases myelin debris that must be cleared by microglia in order for re-myelination to occur. However, phagocytosis can also produce damaging reactive oxygen species (ROS). Furthermore, microglia can acquire pro-inflammatory (M1) or anti-inflammatory (M2) activation states that affect cell functions...
March 24, 2016: Journal of Neuroinflammation
https://www.readbyqxmd.com/read/27008341/whole-genome-and-exome-sequencing-realignment-supports-the-assignment-of-kcnj12-kcnj17-and-kcnj18-paralogous-genes-in-thyrotoxic-periodic-paralysis-locus-functional-characterization-of-two-polymorphic-kir2-6-isoforms
#16
Rolf M Paninka, Diego R Mazzotti, Marina M L Kizys, Angela C Vidi, Hélio Rodrigues, Silas P Silva, Ilda S Kunii, Gilberto K Furuzawa, Manoel Arcisio-Miranda, Magnus R Dias-da-Silva
Next-generation sequencing (NGS) has enriched the understanding of the human genome. However, homologous or repetitive sequences shared among genes frequently produce dubious alignments and can puzzle NGS mutation analysis, especially for paralogous potassium channels. Potassium inward rectifier (Kir) channels are important to establish the resting membrane potential and regulating the muscle excitability. Mutations in Kir channels cause disorders affecting the heart and skeletal muscle, such as arrhythmia and periodic paralysis...
August 2016: Molecular Genetics and Genomics: MGG
https://www.readbyqxmd.com/read/26960267/estrogen-ameliorates-microglial-activation-by-inhibiting-the-kir2-1-inward-rectifier-k-channel
#17
Shih-Ying Wu, Yun-Wen Chen, Sheng-Feng Tsai, Sheng-Nan Wu, Yao-Hsiang Shih, Ya-Fen Jiang-Shieh, Ting-Ting Yang, Yu-Min Kuo
Microglial activation is implicated in the pathogenesis of Parkinson's disease (PD). Although the etiology of PD remains unclear, age and male gender are known PD risk factors. By comparing microglia and dopaminergic (DA) neurons in the substantia nigra (SN) of male and female mice of different ages, we found that the degrees of microglial activation and DA neuron loss increased with age in both genders, but were more pronounced in males, as were peripheral lipopolysaccharide (LPS)-induced microglial activation and DA neuron loss...
2016: Scientific Reports
https://www.readbyqxmd.com/read/26934796/the-beneficial-effects-of-electro-acupuncture-at-pc6-neiguan-point-of-gene-and-protein-expressions-of-classical-inward-rectifier-potassium-channels-in-myocardial-ischemic-rats
#18
Ying Wang, Xiao-Lu Zhang, Wei Wang, Di Li, Jian-Yu Dai, Chun-Ri Li, Ji-Quan Li, Yi-Guo Chen, Pei-Jing Rong
This study is aim to investigate the effect of electro-acupuncture at PC6 (Neiguan-point) on the gene and protein expressions of classical inward-rectifier potassium channels (Kir) in myocardial ischemia (MI) rats induced by isoproterenol (ISO). With ten for each one, 50 rats were divided into 5 groups which were control group, MI group, PC6 group, LU7 (Lieque-point) group and non-acupoint group. The control group was injected normal saline solution (85 mg/kg), the other groups were injected ISO (85 mg/kg)...
2015: Acupuncture & Electro-therapeutics Research
https://www.readbyqxmd.com/read/26840527/inward-rectifier-potassium-kir2-1-channels-as-end-stage-boosters-of-endothelium-dependent-vasodilators
#19
Swapnil K Sonkusare, Thomas Dalsgaard, Adrian D Bonev, Mark T Nelson
KEY POINTS: Increase in endothelial cell (EC) calcium activates calcium-sensitive intermediate and small conductance potassium (IK and SK) channels, thereby causing hyperpolarization and endothelium-dependent vasodilatation. Endothelial cells express inward rectifier potassium (Kir) channels, but their role in endothelium-dependent vasodilatation is not clear. In the mesenteric arteries, only ECs, but not smooth muscle cells, displayed Kir currents that were predominantly mediated by the Kir2...
June 15, 2016: Journal of Physiology
https://www.readbyqxmd.com/read/26702021/automated-patch-clamp-meets-high-throughput-screening-384-cells-recorded-in-parallel-on-a-planar-patch-clamp-module
#20
Alison Obergrussberger, Andrea Brüggemann, Tom A Goetze, Markus Rapedius, Claudia Haarmann, Ilka Rinke, Nadine Becker, Takayuki Oka, Atsushi Ohtsuki, Timo Stengel, Marius Vogel, Juergen Steindl, Max Mueller, Johannes Stiehler, Michael George, Niels Fertig
We have developed an automated patch clamp module for high-throughput ion channel screening, recording from 384 cells simultaneously. The module is incorporated into a laboratory pipetting robot and uses a 384-channel pipettor head for application of cells and compounds. The module contains 384 amplifier channels for fully parallel recordings using a digital amplifier. Success rates for completed experiments (1- to 4-point concentration-response curves for cells satisfying defined quality control parameters) of greater than 85% have been routinely achieved with, for example, HEK, CHO, and RBL cell lines expressing hNaV1...
December 2016: Journal of Laboratory Automation
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