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https://www.readbyqxmd.com/read/28646979/inhibition-of-rapid-delayed-rectifier-potassium-current-ikr-by-ischemia-reperfusion-and-its-recovery-by-vitamin-e-in-ventricular-myocytes
#1
Yaoxu Chen, Chunxia Yin, Yingying Yang, Zhuo Fan, Jinling Shang, Wen Tan
Ischemia/reperfusion (I/R) induces prolongation of QT interval and action potential duration (APD), which is a major cardiac electrical disorder in patients with arrhythmias. However, the mechanism of QT interval prolongation induced by I/R remains unclear. In the present study, we hypothesized that the rapid component of delayed rectifier potassium (IKr) channel plays an important role in I/R-induced QT interval prolongation. We observed a marked attenuation of IKr and a significant prolongation of action potential duration (APD) in a simulated I/R system with sodium dithionite (Na2S2O4) in ventricular myocytes of guinea pigs...
July 2017: Journal of Electrocardiology
https://www.readbyqxmd.com/read/28646163/aldosterone-modulates-the-association-between-ncc-and-enac
#2
Brandi M Wynne, Abinash C Mistry, Otor Al-Khalili, Rickta Mallick, Franziska Theilig, Douglas C Eaton, Robert S Hoover
Distal sodium transport is a final step in the regulation of blood pressure. As such, understanding how the two main sodium transport proteins, the thiazide-sensitive sodium chloride cotransporter (NCC) and the epithelial sodium channel (ENaC), are regulated is paramount. Both are expressed in the late distal nephron; however, no evidence has suggested that these two sodium transport proteins interact. Recently, we established that these two sodium transport proteins functionally interact in the second part of the distal nephron (DCT2)...
June 23, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28645932/a-functional-nav1-7-navab-chimera-with-a-reconstituted-high-affinity-protx-ii-binding-site
#3
Ramkumar Rajamani, Sophie Wu, Iyoncy Rodrigo, Mian Gao, Simon Low, Lisa Megson, David Wensel, Rick Pieschl, Debra Post-Munson, John Watson, David R Langley, Michael Ahlijanian, Linda Bristow, James Herrington
NaV1.7 is genetically implicated in human pain perception. Rare gain of function mutations in NaV1.7 lead to spontaneous pain in humans whereas loss of function mutations result in congenital insensitivity to pain (CIP). Hence, agents that specifically modulate the function of NaV1.7 have the potential to yield novel therapeutics to treat pain. The complexity of the channel and the challenges to generate recombinant cell lines with high NaV1.7 expression have led to a templated target strategy approach employing chimeras with the bacterial channel, NavAb...
June 23, 2017: Molecular Pharmacology
https://www.readbyqxmd.com/read/28642118/current-state-of-the-art-for-cardiac-arrhythmia-gene-therapy
#4
REVIEW
J Kevin Donahue
Cardiac arrhythmias are a leading cause of morbidity and mortality. Currently available therapeutic options lack sufficient efficacy and safety. Gene therapy has been proposed for treatment of cardiac arrhythmias. This review will discuss the current state of development for arrhythmia gene therapy. So far, all published studies are short-term, proof-of-concept animal studies. Potential replacement of cardiac pacemakers has been shown for combination gene therapy using the HCN2 gene and either the gene for adenylate cyclase, the skeletal muscle isoform of the sodium channel, or a dominant negative mutant of the potassium channel responsible for resting membrane potential...
June 19, 2017: Pharmacology & Therapeutics
https://www.readbyqxmd.com/read/28641963/modulation-of-the-heart-s-electrical-properties-by-the-anticonvulsant-drug-retigabine
#5
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/28641116/mechanisms-for-selective-single-cell-reactivation-during-offline-sharp-wave-ripples-and-their-distortion-by-fast-ripples
#6
Manuel Valero, Robert G Averkin, Ivan Fernandez-Lamo, Juan Aguilar, Diego Lopez-Pigozzi, Jorge R Brotons-Mas, Elena Cid, Gabor Tamas, Liset Menendez de la Prida
Memory traces are reactivated selectively during sharp-wave ripples. The mechanisms of selective reactivation, and how degraded reactivation affects memory, are poorly understood. We evaluated hippocampal single-cell activity during physiological and pathological sharp-wave ripples using juxtacellular and intracellular recordings in normal and epileptic rats with different memory abilities. CA1 pyramidal cells participate selectively during physiological events but fired together during epileptic fast ripples...
June 21, 2017: Neuron
https://www.readbyqxmd.com/read/28637969/development-of-a-patient-derived-induced-pluripotent-stem-cell-model-for-the-investigation-of-scn5a-d1275n-related-cardiac-sodium-channelopathy
#7
Mamoru Hayano, Takeru Makiyama, Tsukasa Kamakura, Hiroshi Watanabe, Kenichi Sasaki, Shunsuke Funakoshi, Yimin Wuriyanghai, Suguru Nishiuchi, Takeshi Harita, Yuta Yamamoto, Hirohiko Kohjitani, Sayako Hirose, Fumika Yokoi, Jiarong Chen, Osamu Baba, Takahiro Horie, Kazuhisa Chonabayashi, Seiko Ohno, Futoshi Toyoda, Yoshinori Yoshida, Koh Ono, Minoru Horie, Takeshi Kimura
BACKGROUND: TheSCN5Agene encodes the α subunit of the cardiac voltage-gated sodium channel, NaV1.5. The missense mutation, D1275N, has been associated with a range of unusual phenotypes associated with reduced NaV1.5 function, including cardiac conduction disease and dilated cardiomyopathy. Curiously, the reported biophysical properties ofSCN5A-D1275N channels vary with experimental system.Methods and Results:First, using a human embryonic kidney (HEK) 293 cell-based heterologous expression system, theSCN5A-D1275N channels showed similar maximum sodium conductance but a significantly depolarizing shift of activation gate (+10 mV) compared to wild type...
June 20, 2017: Circulation Journal: Official Journal of the Japanese Circulation Society
https://www.readbyqxmd.com/read/28637420/bioinformatics-insights-on-targets-receptors-of-amiodarone-in-human-and-acanthamoeba-castellanii
#8
Abdul Baig, Zohaib Rana, H R Ahmad
BACKGROUND: Amiodarone is prescribed for certain cardiac arrhythmias in medical practice. The drug targets and inhibits voltage dependent sodium (Na+v), calcium (Ca+2v), potassium (K+v) channels, and enzymes like cytochrome P450 and oxidosqualene cyclase. Past studies have shown that amiodarone exerts anti-amoebic effects against Trypanosoma cruzi and Acanthamoeba castellanii. OBJECTIVES: The presence of aforementioned targets and the type of cell death induced by amiodarone in these pathogenic eukaryotes like Acanthamoeba castellanii remain to be verified...
June 21, 2017: Infectious Disorders Drug Targets
https://www.readbyqxmd.com/read/28635651/effects-of-tetrodotoxin-in-mouse-models-of-visceral-pain
#9
Rafael González-Cano, Miguel Ángel Tejada, Antonia Artacho-Cordón, Francisco Rafael Nieto, José Manuel Entrena, John N Wood, Cruz Miguel Cendán
Visceral pain is very common and represents a major unmet clinical need for which current pharmacological treatments are often insufficient. Tetrodotoxin (TTX) is a potent neurotoxin that exerts analgesic actions in both humans and rodents under different somatic pain conditions, but its effect has been unexplored in visceral pain. Therefore, we tested the effects of systemic TTX in viscero-specific mouse models of chemical stimulation of the colon (intracolonic instillation of capsaicin and mustard oil) and intraperitoneal cyclophosphamide-induced cystitis...
June 21, 2017: Marine Drugs
https://www.readbyqxmd.com/read/28634443/the-narrow-abdomen-ion-channel-complex-is-highly-stable-and-persists-from-development-into-adult-stages-to-promote-behavioral-rhythmicity
#10
Devon L Moose, Stephanie J Haase, Benjamin T Aldrich, Bridget C Lear
The sodium leak channel NARROW ABDOMEN (NA)/ NALCN is an important component of circadian pacemaker neuronal output. In Drosophila, rhythmic expression of the NA channel regulator Nlf-1 in a subset of adult pacemaker neurons has been proposed to contribute to circadian regulation of channel localization or activity. Here we have restricted expression of Drosophila NA channel subunits or the Nlf-1 regulator to either development or adulthood using the temperature-inducible tubulin-GAL80(ts) system. Surprisingly, we find that developmental expression of endogenous channel subunits and Nlf-1 is sufficient to promote robust rhythmic behavior in adults...
2017: Frontiers in Cellular Neuroscience
https://www.readbyqxmd.com/read/28634442/mild-traumatic-brain-injury-evokes-pyramidal-neuron-axon-initial-segment-plasticity-and-diffuse-presynaptic-inhibitory-terminal-loss
#11
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/28633068/multi-electrode-system-for-measurement-of-transmembrane-ion-fluxes-through-living-epithelial-cells
#12
Mirosław Zając, Andrzej Lewenstam, Krzysztof Dolowy
Cystic Fibrosis (CF) is the most common fatal human genetic disease. It is caused by the defect in a single anion channel protein which affects ion and water transport across the epithelial tissue. A flat multi-electrode platform of diameter 12mm, allowing for measurement of four ions: sodium, potassium, hydrogen and chloride by exchangeable/replaceable ion-selective electrodes is described. The measurement is possible owing to the architecture of the platform which accommodates all the electrodes and inlets/outlets...
June 13, 2017: Bioelectrochemistry
https://www.readbyqxmd.com/read/28630432/down-regulation-of-kca2-3-channels-causes-erectile-dysfunction-in-mice
#13
Simon Comerma-Steffensen, Attila Kun, Elise R Hedegaard, Susie Mogensen, Christian Aalkjaer, Ralf Köhler, Birgitte Mønster Christensen, Ulf Simonsen
Modulation of endothelial calcium-activated K(+) channels has been proposed as an approach to restore arterial endothelial cell function in disease. We hypothesized that small-conductance calcium-activated K(+) channels (KCa2.3 or SK3) contributes to erectile function. The research was performed in transgenic mice with overexpression (KCa2.3 (T/T(-Dox))) or down-regulation (KCa2.3 (T/T(+Dox))) of the KCa2.3 channels and wild-type C57BL/6-mice (WT). QPCR revealed that KCa2.3 and KCa1.1 channels were the most abundant in mouse corpus cavernosum...
June 19, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28630169/patient-specific-drug-screening-using-a-human-induced-pluripotent-stem-cell-model-of-catecholaminergic-polymorphic-ventricular-tachycardia-type-2
#14
Leonid Maizels, Irit Huber, Gil Arbel, Anke J Tijsen, Amira Gepstein, Asaad Khoury, Lior Gepstein
BACKGROUND: Catecholaminergic polymorphic ventricular tachycardia type 2 (CPVT2) results from autosomal recessive CASQ2 mutations, causing abnormal Ca(2+)-handling and malignant ventricular arrhythmias. We aimed to establish a patient-specific human induced pluripotent stem cell (hiPSC) model of CPVT2 and to use the generated hiPSC-derived cardiomyocytes to gain insights into patient-specific disease mechanism and pharmacotherapy. METHODS AND RESULTS: hiPSC cardiomyocytes were derived from a CPVT2 patient (D307H-CASQ2 mutation) and from healthy controls...
June 2017: Circulation. Arrhythmia and Electrophysiology
https://www.readbyqxmd.com/read/28629594/the-discovery-of-benzoxazine-sulfonamide-inhibitors-of-nav1-7-tools-that-bridge-efficacy-and-target-engagement
#15
Daniel S La, Emily A Peterson, Christiane Bode, Alessandro A Boezio, Howard Bregman, Margaret Y Chu-Moyer, James Coats, Erin F DiMauro, Thomas A Dineen, Bingfan Du, Hua Gao, Russell Graceffa, Hakan Gunaydin, Angel Guzman-Perez, Robert Fremeau, Xin Huang, Christopher Ilch, Thomas J Kornecook, Charles Kreiman, Joseph Ligutti, Min-Hwa Jasmine Lin, Jeff S McDermott, Isaac Marx, David J Matson, Stefan I McDonough, Bryan D Moyer, Hanh Nho Nguyen, Kristin Taborn, Violeta Yu, Matthew M Weiss
The voltage-gated sodium channel NaV1.7 has received much attention from the scientific community due to compelling human genetic data linking gain- and loss-of-function mutations to pain phenotypes. Despite this genetic validation of NaV1.7 as a target for pain, high quality pharmacological tools facilitate further understanding of target biology, establishment of target coverage requirements and subsequent progression into the clinic. Within the sulfonamide class of inhibitors, reduced potency on rat NaV1...
June 1, 2017: Bioorganic & Medicinal Chemistry Letters
https://www.readbyqxmd.com/read/28621020/conservation-of-alternative-splicing-in-sodium-channels-reveals-evolutionary-focus-on-release-from-inactivation-and-structural-insights-into-gating
#16
A Liavas, G Lignani, S Schorge
Voltage-gated sodium channels are critical for neuronal activity, and highly intolerant to variation. Even mutations that cause subtle changes in the activity these channels are sufficient to cause devastating inherited neurological diseases, such as epilepsy and pain. However, these channels do vary in healthy tissue. Alternative splicing modifies sodium channels, but the functional relevance and adaptive significance of this splicing remain poorly understood. Here we use a conserved alternate exon encoding part of the first domain of sodium channels to compare how splicing modifies different channels, and to ask whether the functional consequences of this splicing have been preserved in different genes...
June 15, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28620319/vascular-endothelial-growth-factor-b-induces-a-distinct-electrophysiological-phenotype-in-mouse-heart
#17
Nikolay Naumenko, Jenni Huusko, Tomi Tuomainen, Jussi T Koivumäki, Mari Merentie, Erika Gurzeler, Kari Alitalo, Riikka Kivelä, Seppo Ylä-Herttuala, Pasi Tavi
Vascular endothelial growth factor B (VEGF-B) is a potent mediator of vascular, metabolic, growth, and stress responses in the heart, but the effects on cardiac muscle and cardiomyocyte function are not known. The purpose of this study was to assess the effects of VEGF-B on the energy metabolism, contractile, and electrophysiological properties of mouse cardiac muscle and cardiac muscle cells. In vivo and ex vivo analysis of cardiac-specific VEGF-B TG mice indicated that the contractile function of the TG hearts was normal...
2017: Frontiers in Physiology
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
#18
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/28617689/paracellular-transport-and-energy-utilization-in-the-renal-tubule
#19
Alan S L Yu
PURPOSE OF REVIEW: Paracellular transport across the tight junction is a general mechanism for transepithelial transport of solutes in epithelia, including the renal tubule. However, why paracellular transport evolved, given the existence of a highly versatile system for transcellular transport, is unknown. RECENT FINDINGS: Recent studies have identified the paracellular channel, claudin-2, that is responsible for paracellular reabsorption of sodium in the proximal renal tubule...
June 14, 2017: Current Opinion in Nephrology and Hypertension
https://www.readbyqxmd.com/read/28615892/molecular-genetics-of-epilepsy-a-clinician-s-perspective
#20
REVIEW
Vikas Dhiman
Epilepsy is a common neurological problem, and there is a genetic basis in almost 50% of people with epilepsy. The diagnosis of genetic epilepsies makes the patient assured of the reasons of his/her seizures and avoids unnecessary, expensive, and invasive investigations. Last decade has shown tremendous growth in gene sequencing technologies, which have made genetic tests available at the bedside. Whole exome sequencing is now being routinely used in the clinical setting for making a genetic diagnosis. Genetic testing not only makes the diagnosis but also has an effect on the management of the patients, for example, the role of sodium channels blockers in SCN1A+ Dravet syndrome patients and usefulness of ketogenic diet therapy in SLC2A1+ generalized epilepsy patients...
April 2017: Annals of Indian Academy of Neurology
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