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Late sodium current

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https://www.readbyqxmd.com/read/28436159/the-mechanism-research-of-hypoxia-induced-increased-late-sodium-current-resulting-in-intracellular-ca-2-overload-in-ventricular-myocytes
#1
Chen Fu, Jie Hao, Mengliu Zeng, Yejia Song, Wanzhen Jiang, Peihua Zhang, Antao Luo, Zhenzhen Cao, Luiz Belardinelli, Jihua Ma
Hypoxia leads to augmentation of late sodium current (INa.L ) and cellular Na(+) loading, increased reverse Na(+) -Ca(2+) exchange current (reverse INCX ) and intracellular Ca(2+) loading in rabbit ventricular myocytes. The purpose of this study was to determine the intracellular signal transduction pathways involved in the modulation of INa.L during hypoxia in ventricular myocytes. Whole-cell and cell-attached patch clamp techniques were used to record INa.L , and the whole-cell mode was also used to record reverse INCX and to study intercellular signal transduction mechanisms that mediate the increased INa...
April 24, 2017: Experimental Physiology
https://www.readbyqxmd.com/read/28430892/anti-arrhythmic-potential-of-the-late-sodium-current-inhibitor-gs-458967-in-murine-scn5a-1798insd-and-human-scn5a-1795insd-ipsc-derived-cardiomyocytes
#2
Vincent Portero, Simona Casini, Maaike Hoekstra, Arie O Verkerk, Isabella Mengarelli, Luiz Belardinelli, Sridharan Rajamani, Arthur A M Wilde, Connie R Bezzina, Marieke W Veldkamp, Carol Ann Remme
AIM: Selective inhibition of cardiac late sodium current (INaL) is an emerging target in the treatment of ventricular arrhythmias. We investigated the electrophysiological effects of GS-458967 (GS967), a potent, selective inhibitor of INaL, in an overlap syndrome model of both gain and loss of sodium channel function, comprising cardiomyocytes derived from both human SCN5A-1795insD+/- induced pluripotent stem cells (hiPSC-CMs) and mice carrying the homologous mutation Scn5a-1798insD+/-...
April 18, 2017: Cardiovascular Research
https://www.readbyqxmd.com/read/28428622/inhibition-of-late-sodium-current-suppresses-calcium-related-ventricular-arrhythmias-by-reducing-the-phosphorylation-of-camk-ii-and-sodium-channel-expressions
#3
Xiao-Hong Wei, Shan-Dong Yu, Lu Ren, Si-Hui Huang, Qiao-Mei Yang, Ping Wang, Yan-Peng Chu, Wei Yang, Yan-Sheng Ding, Yong Huo, Lin Wu
Cardiac arrhythmias associated with intracellular calcium inhomeostasis are refractory to antiarrhythmic therapy. We hypothesized that late sodium current (I Na) contributed to the calcium-related arrhythmias. Monophasic action potential duration at 90% completion of repolarization (MAPD90) was significantly increased and ventricular arrhythmias were observed in hearts with increased intracellular calcium concentration ([Ca(2+)]i) by using Bay K 8644, and the increase became greater in hearts treated with a combination of ATX-II and Bay K 8644 compared to Bay K 8644 alone...
April 20, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28413579/metabolic-recovery-of-the-failing-heart-emerging-therapeutic-options
#4
Dale J Hamilton
Heart failure has mortality rates that parallel those of breast cancer. Current management strategies include neurohormonal blockade, rate control measures, natriuretic peptide preservation, implantation of mechanical assist devices, and heart transplantation. Despite these strategies, however, the failing myocardium remains energy depleted. New strategies to promote metabolic recovery are being developed to potentially augment current treatment guidelines. For example, an unexpected finding of our own studies showed that mechanical unloading with assist devices in advanced-stage heart failure restored metabolic flux...
January 2017: Methodist DeBakey Cardiovascular Journal
https://www.readbyqxmd.com/read/28412158/lidocaine-attenuation-testing-an-in-vivo-investigation-of-putative-lqt3-associated-variants-in-the-scn5a-encoded-sodium-channel
#5
M D Heather N Anderson, J Martijn Bos, Jamie D Kapplinger, Jana M Meskill, Dan Ye, Michael J Ackerman
BACKGROUND: Long QT type 3 (LQT3) accounts for 5-10% of LQTS and results from gain-of-function mutations in the SCN5A-encoded sodium channel. Nearly 2% of healthy individuals host rare SCN5A variants of uncertain significance (VUS). Distinction of true LQT3-causative mutations from background genetic noise is essential. OBJECTIVE: This study was designed to assess the utility of the lidocaine attenuation test (LAT) in evaluating patients with possible LQT3. METHODS: We reviewed LAT results and medical records for 25 patients with a possible LQT3-associated SCN5A variant...
April 12, 2017: Heart Rhythm: the Official Journal of the Heart Rhythm Society
https://www.readbyqxmd.com/read/28379373/genetic-and-phenotypic-heterogeneity-suggest-therapeutic-implications-in-scn2a-related-disorders
#6
Markus Wolff, Katrine M Johannesen, Ulrike B S Hedrich, Silvia Masnada, Guido Rubboli, Elena Gardella, Gaetan Lesca, Dorothée Ville, Mathieu Milh, Laurent Villard, Alexandra Afenjar, Sandra Chantot-Bastaraud, Cyril Mignot, Caroline Lardennois, Caroline Nava, Niklas Schwarz, Marion Gérard, Laurence Perrin, Diane Doummar, Stéphane Auvin, Maria J Miranda, Maja Hempel, Eva Brilstra, Nine Knoers, Nienke Verbeek, Marjan van Kempen, Kees P Braun, Grazia Mancini, Saskia Biskup, Konstanze Hörtnagel, Miriam Döcker, Thomas Bast, Tobias Loddenkemper, Lily Wong-Kisiel, Friedrich M Baumeister, Walid Fazeli, Pasquale Striano, Robertino Dilena, Elena Fontana, Federico Zara, Gerhard Kurlemann, Joerg Klepper, Jess G Thoene, Daniel H Arndt, Nicolas Deconinck, Thomas Schmitt-Mechelke, Oliver Maier, Hiltrud Muhle, Beverly Wical, Claudio Finetti, Reinhard Brückner, Joachim Pietz, Günther Golla, Dinesh Jillella, Karen M Linnet, Perrine Charles, Ute Moog, Eve Õiglane-Shlik, John F Mantovani, Kristen Park, Marie Deprez, Damien Lederer, Sandrine Mary, Emmanuel Scalais, Laila Selim, Rudy Van Coster, Lieven Lagae, Marina Nikanorova, Helle Hjalgrim, G Christoph Korenke, Marina Trivisano, Nicola Specchio, Berten Ceulemans, Thomas Dorn, Katherine L Helbig, Katia Hardies, Hannah Stamberger, Peter de Jonghe, Sarah Weckhuysen, Johannes R Lemke, Ingeborg Krägeloh-Mann, Ingo Helbig, Gerhard Kluger, Holger Lerche, Rikke S Møller
Mutations in SCN2A, a gene encoding the voltage-gated sodium channel Nav1.2, have been associated with a spectrum of epilepsies and neurodevelopmental disorders. Here, we report the phenotypes of 71 patients and review 130 previously reported patients. We found that (i) encephalopathies with infantile/childhood onset epilepsies (≥3 months of age) occur almost as often as those with an early infantile onset (<3 months), and are thus more frequent than previously reported; (ii) distinct phenotypes can be seen within the late onset group, including myoclonic-atonic epilepsy (two patients), Lennox-Gastaut not emerging from West syndrome (two patients), and focal epilepsies with an electrical status epilepticus during slow sleep-like EEG pattern (six patients); and (iii) West syndrome constitutes a common phenotype with a major recurring mutation (p...
March 4, 2017: Brain: a Journal of Neurology
https://www.readbyqxmd.com/read/28361599/antianginal-therapy-for-stable-ischemic-heart-disease
#7
Santosh K Padala, Michael P Lavelle, Mandeep S Sidhu, Katherine P Cabral, Doralisa Morrone, William E Boden, Peter P Toth
Chronic angina pectoris is associated with considerable morbidity and mortality, especially if treated suboptimally. For many patients, aggressive pharmacologic intervention is necessary in order to alleviate anginal symptoms. The optimal treatment of stable ischemic heart disease (SIHD) should be the prevention of angina and ischemia, with the goal of maximizing both quality and quantity of life. In addition to effective risk factor modification with lifestyle changes, intensive pharmacologic secondary prevention is the therapeutic cornerstone in managing patients with SIHD...
January 1, 2017: Journal of Cardiovascular Pharmacology and Therapeutics
https://www.readbyqxmd.com/read/28358314/oxidative-stress-induced-afterdepolarizations-and-protein-kinase-c-signaling
#8
Yu-Dong Fei, Wei Li, Jian-Wen Hou, Kai Guo, Xiao-Meng Chen, Yi-He Chen, Qian Wang, Xiao-Lei Xu, Yue-Peng Wang, Yi-Gang Li
BACKGROUND: Hydrogen peroxide (H₂O₂)-induced oxidative stress has been demonstrated to induce afterdepolarizations and triggered activities in isolated myocytes, but the underlying mechanisms remain not fully understood. We aimed to explore whether protein kinase C (PKC) activation plays an important role in oxidative stress-induced afterdepolarizations. METHODS: Action potentials and ion currents of isolated rabbit cardiomyocytes were recorded using the patch clamp technique...
March 30, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/28352365/heart-failure-modulates-electropharmacological-characteristics-of-sinoatrial-nodes
#9
Shih-Lin Chang, Hui-Lun Chuang, Yao-Chang Chen, Yu-Hsun Kao, Yung-Kuo Lin, Yung-Hsin Yeh, Shih-Ann Chen, Yi-Jen Chen
The impact of heart failure (HF) on sinoatrial node (SAN) channel regulation and electropharmacological responses has remained elusive. The present study aimed to investigate the effects of HF on the electrical activity of SANs with and without pharmacological interventions. Action potentials (APs) were recorded in isolated SANs from normal rabbits (control) and those with HF (rapid ventricular pacing for 4 weeks) prior to and after administration of a funny current blocker (ivabradine; 0.1, 0.3, 3 or 10 µM), a calmodulin kinase II inhibitor (KN-93; 0...
February 2017: Experimental and Therapeutic Medicine
https://www.readbyqxmd.com/read/28336914/inhibition-of-serum-and-glucocorticoid-regulated-kinase-1-as-novel-therapy-for-cardiac-arrhythmia-disorders
#10
Vassilios J Bezzerides, Aifeng Zhang, Ling Xiao, Bridget Simonson, Santosh A Khedkar, Shiro Baba, Filomena Ottaviano, Stacey Lynch, Katherine Hessler, Alan C Rigby, David Milan, Saumya Das, Anthony Rosenzweig
Alterations in sodium flux (INa) play an important role in the pathogenesis of cardiac arrhythmias and may also contribute to the development of cardiomyopathies. We have recently demonstrated a critical role for the regulation of the voltage-gated sodium channel NaV1.5 in the heart by the serum and glucocorticoid regulated kinase-1 (SGK1). Activation of SGK1 in the heart causes a marked increase in both the peak and late sodium currents leading to prolongation of the action potential duration and an increased propensity to arrhythmia...
March 23, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28314848/effects-of-late-sodium-current-blockade-on-ventricular-refibrillation-in-a-rabbit-model
#11
Mohammed Ali Azam, Nima Zamiri, Stéphane Massé, Marjan Kusha, Patrick F H Lai, Govind K Nair, Nigel S Tan, Christopher Labos, Kumaraswamy Nanthakumar
BACKGROUND: After defibrillation of initial ventricular fibrillation (VF), it is crucial to prevent refibrillation to ensure successful resuscitation outcomes. Inability of the late Na(+) current to inactivate leads to intracellular Ca(2+) dysregulation and arrhythmias. Our aim was to determine the effects of ranolazine and GS-967, inhibitors of the late Na(+) current, on ventricular refibrillation. METHODS AND RESULTS: Long-duration VF was induced electrically in Langendorff-perfused rabbit hearts (n=22) and terminated with a defibrillator after 6 minutes...
March 2017: Circulation. Arrhythmia and Electrophysiology
https://www.readbyqxmd.com/read/28265756/sodium-channel-biophysics-late-sodium-current-and-genetic-arrhythmic-syndromes
#12
REVIEW
Karan R Chadda, Kamalan Jeevaratnam, Ming Lei, Christopher L-H Huang
Arrhythmias arise from breakdown of orderly action potential (AP) activation, propagation and recovery driven by interactive opening and closing of successive voltage-gated ion channels, in which one or more Na(+) current components play critical parts. Early peak, Na(+) currents (I Na) reflecting channel activation drive the AP upstroke central to cellular activation and its propagation. Sustained late Na(+) currents (I Na-L) include contributions from a component with a delayed inactivation timecourse influencing AP duration (APD) and refractoriness, potentially causing pro-arrhythmic phenotypes...
March 6, 2017: Pflügers Archiv: European Journal of Physiology
https://www.readbyqxmd.com/read/28243733/biophysical-and-molecular-comparison-of-sodium-current-in-cells-isolated-from-canine-atria-and-pulmonary-vein
#13
Hector Barajas-Martinez, Robert J Goodrow, Dan Hu, Payal Patel, Mayurika Desai, Brian K Panama, Jacqueline A Treat, Gary L Aistrup, Jonathan M Cordeiro
The collar of the pulmonary vein (PV) is the focal point for the initiation of atrial arrhythmias, but the mechanisms underlying how PV cells differ from neighboring left atrial tissue are unclear. We examined the biophysical and molecular properties of INa in cells isolated from the canine pulmonary sleeve and compared the properties to left atrial tissue. PV and left atrial myocytes were isolated and patch clamp techniques were used to record INa. Action potential recordings from either tissue type were made using high-resistance electrodes...
February 27, 2017: Pflügers Archiv: European Journal of Physiology
https://www.readbyqxmd.com/read/28213505/revealing-the-concealed-nature-of-long-qt-type-3-syndrome
#14
Amara Greer-Short, Sharon A George, Steven Poelzing, Seth H Weinberg
BACKGROUND: Gain-of-function mutations in the voltage-gated sodium channel (Nav1.5) are associated with the long-QT-3 (LQT3) syndrome. Nav1.5 is densely expressed at the intercalated disk, and narrow intercellular separation can modulate cell-to-cell coupling via extracellular electric fields and depletion of local sodium ion nanodomains. Models predict that significantly decreasing intercellular cleft widths slows conduction because of reduced sodium current driving force, termed "self-attenuation...
February 2017: Circulation. Arrhythmia and Electrophysiology
https://www.readbyqxmd.com/read/28202629/improving-the-in-silico-assessment-of-proarrhythmia-risk-by-combining-herg-human-ether-%C3%A3-go-go-related-gene-channel-drug-binding-kinetics-and-multichannel-pharmacology
#15
Zhihua Li, Sara Dutta, Jiansong Sheng, Phu N Tran, Wendy Wu, Kelly Chang, Thembi Mdluli, David G Strauss, Thomas Colatsky
BACKGROUND: The current proarrhythmia safety testing paradigm, although highly efficient in preventing new torsadogenic drugs from entering the market, has important limitations that can restrict the development and use of valuable new therapeutics. The CiPA (Comprehensive in vitro Proarrhythmia Assay) proposes to overcome these limitations by evaluating drug effects on multiple cardiac ion channels in vitro and using these data in a predictive in silico model of the adult human ventricular myocyte...
February 2017: Circulation. Arrhythmia and Electrophysiology
https://www.readbyqxmd.com/read/28185917/increment-of-late-sodium-currents-in-the-left-atrial-myocytes-and-its-potential-contribution-to-increased-susceptibility-of-atrial-fibrillation-in-castrated-male-mice
#16
Yang Zhang, Hui-Min Wang, Ying-Zhe Wang, Yi-Yuan Zhang, Xue-Xin Jin, Yue Zhao, Jin Wang, Yi-Lin Sun, Gen-Long Xue, Peng-Hui Li, Qi-He Huang, Bao-Feng Yang, Zhen-Wei Pan
BACKGROUND: The incidence of atrial fibrillation (AF) is correlated with decreased levels of testosterone in elderly men. Late sodium current may exert a role in AF pathogenesis. OBJECTIVE: The purpose of this study was to explore the effect of testosterone deficiency on AF susceptibility and the therapeutic effect of late sodium current inhibitors in mice. METHODS: Male ICR mice (5 weeks old) were castrated to establish a testosterone deficiency model...
February 6, 2017: Heart Rhythm: the Official Journal of the Heart Rhythm Society
https://www.readbyqxmd.com/read/28151960/d-amino-acids-reduce-enterococcus-faecalis-biofilms-in-vitro-and-in-the-presence-of-antimicrobials-used-for-root-canal-treatment
#17
Peter S Zilm, Victor Butnejski, Giampiero Rossi-Fedele, Stephen P Kidd, Suzanne Edwards, Krasimir Vasilev
Enterococcus faecalis is the most frequent species present in post-treatment disease and plays a significant role in persistent periapical infections following root canal treatment. Its ability to persist in stressful environments is inter alia, due to its ability to form biofilms. The presence of certain D-amino acids (DAAs) has previously been shown to reduce formation of Bacillus subtilis biofilms. The aims of this investigation were to determine if DAAs disrupt biofilms in early and late growth stages for clinical E...
2017: PloS One
https://www.readbyqxmd.com/read/28148645/nonlinear-effects-of-hyperpolarizing-shifts-in-activation-of-mutant-nav1-7-channels-on-resting-membrane-potential
#18
Mark Estacion, Stephen G Waxman
The Nav1.7 sodium channel is preferentially expressed within dorsal root ganglion (DRG) and sympathetic ganglion neurons. Gain-of-function mutations that cause the painful disorder inherited erythromelalgia (IEM) shift channel activation in a hyperpolarizing direction. When expressed within DRG neurons, these mutations produce a depolarization of resting membrane potential (RMP). The biophysical basis for the depolarized RMP has to date not been established. To explore the effect on RMP of the shift in activation associated with a prototypical IEM mutation (L858H), we used dynamic-clamp models that represent graded shifts that fractionate the effect of the mutation on activation voltage dependence...
April 1, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/28125029/excavatolide-b-modulates-the-electrophysiological-characteristics-and-calcium-homeostasis-of-atrial-myocytes
#19
Hwong-Ru Hwang, Buh-Yuan Tai, Pao-Yun Cheng, Ping-Nan Chen, Ping-Jyun Sung, Zhi-Hong Wen, Chih-Hsueng Hsu
Severe bacterial infections caused by sepsis always result in profound physiological changes, including fever, hypotension, arrhythmia, necrosis of tissue, systemic multi-organ dysfunction, and finally death. The lipopolysaccharide (LPS) provokes an inflammatory response under sepsis, which may increase propensity to arrhythmogenesis. Excavatolide B (EXCB) possesses potent anti-inflammatory effects. However, it is not clear whether EXCB could modulate the electrophysiological characteristics and calcium homeostasis of atrial myocytes...
January 24, 2017: Marine Drugs
https://www.readbyqxmd.com/read/28117139/epigallocatechin-3-gallate-modulates-arrhythmogenic-activity-and-calcium-homeostasis-of-left-atrium
#20
Jun-Hei Chang, Shih-Lin Chang, Po-Da Hong, Ping-Nan Chen, Chih-Hsueng Hsu, Yen-Yu Lu, Yao-Chang Chen
BACKGROUND: Atrial fibrillation (AF) is the commonest sustained arrhythmia, and increases the risk of stroke, heart failure, and mortality. Calcium (Ca(2+)) overload and oxidative stress are thought to participate in the pathogenesis of AF. Epigallocatechin-3-gallate (EGCG) has an antioxidative effect and been shown to be beneficial in promoting cardiovascular health. However, it is not clear if EGCG directly modulates the electrophysiological characteristics and Ca(2+) homeostasis of the left atrium (LA)...
January 14, 2017: International Journal of Cardiology
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