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Late sodium current

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https://www.readbyqxmd.com/read/28756335/computational-approaches-to-understand-the-adverse-drug-effect-on-potassium-sodium-and-calcium-channels-for-predicting-tdp-cardiac-arrhythmias
#1
Mohsen Sharifi
Ion channels play a crucial role in the cardiovascular system. Our understanding of cardiac ion channel function has improved since their first discoveries. The flow of potassium, sodium and calcium ions across cardiomyocytes is vital for regular cardiac rhythm. Blockage of these channels, delays cardiac repolarization or tend to shorten repolarization and may induce arrhythmia. Detection of drug risk by channel blockade is considered essential for drug regulators. Advanced computational models can be used as an early screen for torsadogenic potential in drug candidates...
July 8, 2017: Journal of Molecular Graphics & Modelling
https://www.readbyqxmd.com/read/28756098/phenotypic-variability-in-lqt3-human-induced-pluripotent-stem-cell-derived-cardiomyocytes-and-their-response-to-antiarrhythmic-pharmacologic-therapy-an-in-silico-approach
#2
Michelangelo Paci, Elisa Passini, Stefano Severi, Jari Hyttinen, Blanca Rodriguez
BACKGROUND: Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) are in vitro models with the clear advantages of their human origin and suitability for human disease investigations. However, limitations include their incomplete characterization and variability reported in different cell lines and laboratories. OBJECTIVE: The purpose of this study was to investigate in silico ionic mechanisms potentially explaining the phenotypic variability of hiPSC-CMs in long QT syndrome type 3 (LQT3) and their response to antiarrhythmic drugs...
July 27, 2017: Heart Rhythm: the Official Journal of the Heart Rhythm Society
https://www.readbyqxmd.com/read/28734073/differential-calcium-sensitivity-in-nav-1-5-mixed-syndrome-mutants
#3
Mena Abdelsayed, Alban-Elouen Baruteau, Karen Gibbs, Shubhayan Sanatani, Andrew D Krahn, Vincent Probst, Peter C Ruben
INTRODUCTION: Inherited arrhythmias may arise from mutations in the SCN5a gene, which encodes the cardiac voltage-gated sodium channel, NaV 1.5. Mutants in NaV 1.5 result in Brugada Syndrome (BrS1), Long-QT Syndrome (LQT3), or mixed syndromes (an overlap of BrS1/LQT3). Exercise is a potential arrhythmogenic trigger in mixed syndromes. We sought to determine the effects of elevated cytosolic calcium, common during exercise, in mixed syndrome NaV 1.5 mutants. METHODS: We used whole-cell patch-clamp to assess the biophysical properties of NaV 1...
July 22, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28701305/redox-and-activation-of-protein-kinase-a-dysregulates-calcium-homeostasis-in-pulmonary-vein-cardiomyocytes-of-chronic-kidney-disease
#4
Shih-Yu Huang, Yao-Chang Chen, Yu-Hsun Kao, Ming-Hsiung Hsieh, Yung-Kuo Lin, Shih-Ann Chen, Yi-Jen Chen
BACKGROUND: Chronic kidney disease (CKD) increases the occurrence of atrial fibrillation and pulmonary vein (PV) arrhythmogenesis. Calcium dysregulation and reactive oxygen species (ROS) enhance PV arrhythmogenic activity. The purposes of this study were to investigate whether CKD modulates PV electrical activity through dysregulation of calcium homeostasis and ROS. METHODS AND RESULTS: Biochemical and electrocardiographic studies were conducted in rabbits with and without CKD (induced by 150 mg/kg per day neomycin sulfate and 500 mg/kg per day cefazolin)...
July 12, 2017: Journal of the American Heart Association
https://www.readbyqxmd.com/read/28692548/comparison-of-vernakalant-and-ranolazine-in-atrial-fibrillation
#5
Gerrit Frommeyer, Magdalena Sterneberg, Dirk G Dechering, Simon Kochhäuser, Nils Bögeholz, Michael Fehr, Lars Eckardt
BACKGROUND: Current guidelines recommend vernakalant for pharmacologic cardioversion of recent-onset atrial fibrillation. However, this drug is not established as chronic therapy. METHODS AND RESULTS: In total, 15 rabbit hearts were Langendorff-perfused. A burst pacing protocol-induced atrial fibrillation in 7 of 15 hearts at baseline (10 episodes). Subsequently, a combination of acetylcholine and isoproterenol (ACH/ISO) has been administered to increase occurrence of atrial fibrillation resulting in a reduction of atrial action potential duration (-25 ms, P < 0...
September 2017: Journal of Cardiovascular Medicine
https://www.readbyqxmd.com/read/28654510/late-ina-inhibition-as-an-antiarrhythmic-strategy
#6
Alexander Burashnikov
Late sodium channel current (late INa) is considered to be an anti-arrhythmic target. The prime anti-arrhythmic mechanisms of late INa inhibition have been suggested to be 1) suppression of intracellular calcium [Cai]-mediated rhythmic activity (via reduction of Cai secondary to the decrease of intracellular sodium [Nai]) and 2) normalization of repolarization. Endogenous late INa is a small current and acceleration of heart rate decreases late INa density. Late INa influx may significantly contribute to Nai loading, but it appears to largely occur in the combined conditions of augmented late INa density, bradycardia, and prolonged repolarization...
June 22, 2017: Journal of Cardiovascular Pharmacology
https://www.readbyqxmd.com/read/28554967/basal-late-sodium-current-is-a-significant-contributor-to-the-duration-of-action-potential-of-guinea-pig-ventricular-myocytes
#7
Yejia Song, Luiz Belardinelli
In cardiac myocytes, an enhancement of late sodium current (INaL) under pathological conditions is known to cause prolongation of action potential duration (APD). This study investigated the contribution of INaL under basal, physiological conditions to the APD Whole-cell INaL and the APD of ventricular myocytes isolated from healthy adult guinea pigs were measured at 36°C. The INaL inhibitor GS967 or TTX was applied to block INaL The amplitude of basal INaL and the APD at 50% repolarization in myocytes stimulated at a frequency of 0...
May 2017: Physiological Reports
https://www.readbyqxmd.com/read/28552050/readthrough-of-scn5a-nonsense-mutations-r1623x-and-s1812x-question-gene-therapy-in-brugada-syndrome
#8
Siyong Teng, Jian Huang, Zhan Gao, Jie Hao, Yuejin Yang, Shu Zhang, Jielin Pu, Rutai Hui, Yongjian Wu, Zheng Fan
PURPOSE: Readthrough of nonsense mutation are used as gene-specific treatment in some genetic disease. Response to readthrough treatment is determined by readthrough efficiency of various nonsense mutations. In this manuscript, we aimed to explore the harmful effect of nonsense mutation suppressions. METHODS: HEK293 cells were transfected with two SCN5A (encode cardiac Na+ channel) nonsense mutations, p.R1623X and p.S1812X. We applied two readthrough-enhancing methods (either aminoglycosides or by a siRNA targeting eukaryotic release factor eRF3a (a GTPase that binds eRF1)) to suppress these SCN5A nonsense mutations...
May 28, 2017: Current Gene Therapy
https://www.readbyqxmd.com/read/28530796/what-do-laser-induced-transient-techniques-reveal-for-batteries-na-and-k-intercalation-from-aqueous-electrolytes-as-an-example
#9
Daniel Scieszka, Jeongsik Yun, Aliaksandr S Bandarenka
Technological advancement has been revolutionized by rechargeable batteries, without which the use of various modern devices would not be possible. Aqueous Na ion batteries have lately garnered much attention, being recognized as a promising alternative to the commonly used Li ion batteries for the large-scale energy storage systems. However, further improvement and optimization of such systems require a more detailed understanding of intercalation mechanisms. In this work, we for the first time demonstrate the implementation of the laser-induced current transient (LICT) technique for in situ characterization of battery systems and investigate the interface between Na2Ni[Fe(CN)6] model battery electrodes and aqueous electrolytes in contact with aqueous electrolytes...
May 31, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28527083/shared-mechanisms-of-epilepsy-migraine-and-affective-disorders
#10
Davide Zarcone, Simona Corbetta
Since the nineteenth century several clinical features have been observed in common between migraine and epilepsy (such as episodic attacks, triggering factors, presence of aura, frequent familiarity), but only in recent years researchers have really engaged in finding a common pathogenic mechanism. From studies of disease incidence, we understand how either migraine among patients with epilepsy or epilepsy among migraine patients are more frequent than in the general population. This association may result from a direct causality, by the same environmental risk factors and/or by a common genetic susceptibility...
May 2017: Neurological Sciences
https://www.readbyqxmd.com/read/28481659/ion-channel-mechanisms-underlying-frequency-firing-patterns-of-the-avian-nucleus-magnocellularis-a-computational-model
#11
Ting Lu, Kirstie Wade, Hui Hong, Jason Tait Sanchez
We have previously shown that late-developing avian nucleus magnocellularis (NM) neurons (embryonic [E] days 19-21) fire action potentials (APs) that resembles a band-pass filter in response to sinusoidal current injections of varying frequencies. NM neurons located in the mid- to high-frequency regions of the nucleus fire preferentially at 75 Hz, but only fire a single onset AP to frequency inputs greater than 200 Hz. Surprisingly, NM neurons do not fire APs to sinusoidal inputs less than 20 Hz regardless of the strength of the current injection...
May 8, 2017: Channels
https://www.readbyqxmd.com/read/28455610/inhibition-of-late-sodium-current-as-an-innovative-antiarrhythmic-strategy
#12
REVIEW
Philipp Bengel, Shakil Ahmad, Samuel Sossalla
PURPOSE OF REVIEW: Over the last years, evidence is accumulating that enhanced late sodium current (INaL) in cardiac pathologies has fundamental consequences for cellular electrophysiology. This review discusses the underlying mechanisms of INaL-induced arrhythmias and the significance of INaL-inhibition as a possible therapeutic approach. RECENT FINDINGS: Inhibition of enhanced INaL, e.g., by ranolazine, was shown to reverse these effects in different myocardial diseases including heart failure...
June 2017: Current Heart Failure Reports
https://www.readbyqxmd.com/read/28436159/modulation-of-late-sodium-current-by-ca-2-calmodulin-dependent-protein-kinase-ii-protein-kinase-c-and-ca-2-during-hypoxia-in-rabbit-ventricular-myocytes
#13
Chen Fu, Jie Hao, Mengliu Zeng, Yejia Song, Wanzhen Jiang, Peihua Zhang, Antao Luo, Zhenzhen Cao, Luiz Belardinelli, Jihua Ma
What is the central question of this study? Hypoxia-induced increase in late sodium current (INa,L ) is associated with conditions causing cellular Ca(2+) overload and contributes to arrhythmogenesis in the ventricular myocardium. The INa,L is an important drug target. We investigated intracellular signal transduction pathways involved in modulation of INa,L during hypoxia. What is the main finding and its importance? Hypoxia caused increases in INa,L , reverse Na(+) -Ca(2+) exchange current and diastolic [Ca(2+) ], which were attenuated by inhibitors of Ca(2+) -calmodulin-dependent protein kinase II (CaMKII) and protein kinase C and by a Ca(2+) chelator...
July 1, 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
#14
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
Aims: 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+/-...
June 1, 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
#15
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
#16
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%C3%A2-vivo-investigation-of-putative-lqt3-associated-variants-in-the-scn5a-encoded-sodium-channel
#17
Heather N Anderson, J Martijn Bos, Jamie D Kapplinger, Jana M Meskill, Dan Ye, Michael J Ackerman
BACKGROUND: Long QT syndrome type 3 (LQT3) accounts for 5%-10% of long QT syndrome and results from gain-of-function mutations in the SCN5A-encoded sodium channel. Approximately 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: The purpose of this study was to assess the use of the lidocaine attenuation test (LAT) in evaluating patients with possible LQT3...
April 13, 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
#18
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
#19
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
#20
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
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