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Ventricular depolarization

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https://www.readbyqxmd.com/read/29457789/a-common-variant-alters-scn5a-mir-24-interaction-and-associates-with-heart-failure-mortality
#1
Xiaoming Zhang, Jin-Young Yoon, Michael Morley, Jared M McLendon, Kranti A Mapuskar, Rebecca Gutmann, Haider Mehdi, Heather L Bloom, Samuel C Dudley, Patrick T Ellinor, Alaa A Shalaby, Raul Weiss, W H Wilson Tang, Christine S Moravec, Madhurmeet Singh, Anne L Taylor, Clyde W Yancy, Arthur M Feldman, Dennis M McNamara, Kaikobad Irani, Douglas R Spitz, Patrick Breheny, Kenneth B Margulies, Barry London, Ryan L Boudreau
SCN5A encodes the voltage-gated Na+ channel NaV1.5 that is responsible for depolarization of the cardiac action potential and rapid intercellular conduction. Mutations disrupting the SCN5A coding sequence cause inherited arrhythmias and cardiomyopathy, and single-nucleotide polymorphisms (SNPs) linked to SCN5A splicing, localization, and function associate with heart failure-related sudden cardiac death. However, the clinical relevance of SNPs that modulate SCN5A expression levels remains understudied. We recently generated a transcriptome-wide map of microRNA (miR) binding sites in human heart, evaluated their overlap with common SNPs, and identified a synonymous SNP (rs1805126) adjacent to a miR-24 site within the SCN5A coding sequence...
February 19, 2018: Journal of Clinical Investigation
https://www.readbyqxmd.com/read/29431104/reep5-receptor-accessory-protein-5-acts-as-a-sarcoplasmic-reticulum-membrane-sculptor-to-modulate-cardiac-function
#2
Lei Yao, Duanyang Xie, Li Geng, Dan Shi, Jian Huang, Yufei Wu, Fei Lv, Dandan Liang, Li Li, Yi Liu, Jun Li, Yi-Han Chen
BACKGROUND: Heart failure is a complex syndrome characterized by cardiac contractile impairment with high mortality. Defective intracellular Ca2+ homeostasis is the central cause under this scenario and tightly links to ultrastructural rearrangements of sarcolemmal transverse tubules and the sarcoplasmic reticulum (SR); however, the modulators of the SR architecture remain unknown. The SR has been thought to be a specialized endoplasmic reticulum membrane system. Receptor accessory proteins (REEPs)/DP1/Yop1p are responsible for shaping high-curvature endoplasmic reticulum tubules...
February 3, 2018: Journal of the American Heart Association
https://www.readbyqxmd.com/read/29430560/epilepsy-is-associated-with-ventricular-alterations-following-convulsive-status-epilepticus-in-children
#3
Wail Ali, Beth A Bubolz, Linh Nguyen, Danny Castro, Jorge Coss-Bu, Michael M Quach, Curtis E Kennedy, Anne E Anderson, Yi-Chen Lai
Objective: Convulsive status epilepticus can exert profound cardiovascular effects in adults including ventricular depolarization-repolarization abnormalities. Whether status epilepticus adversely affects ventricular electrical properties in children is less understood. Therefore, we sought to characterize ventricular alterations and the associated clinical factors in children following convulsive status epilepticus. Methods: We conducted a 2-year retrospective, case-control study...
December 2017: Epilepsia Open
https://www.readbyqxmd.com/read/29428145/his-bundle-pacing-is-it-ready-for-prime-time
#4
REVIEW
Fatima M Ezzeddine, Gopi Dandamudi
Long-term right ventricular apical pacing has been associated with detrimental effects, including an increased risk for heart failure, atrial fibrillation, and death. Most of these adverse effects result from ventricular dyssynchrony related to perturbed ventricular depolarization. In addition, biventricular pacing has limited benefits in patients with non-left bundle branch block and severely reduced ejection fraction. Consequently, alternative pacing strategies that mimic natural physiology are desired. Recently, permanent His bundle pacing has emerged as a true physiologic form of ventricular pacing that has been shown to be safe and feasible in clinical practice...
March 2018: Cardiac Electrophysiology Clinics
https://www.readbyqxmd.com/read/29420146/methylene-blue-counteracts-cyanide-cardiotoxicity-cellular-mechanisms
#5
Joseph Y Cheung, JuFang Wang, Xue-Qian Zhang, Jianliang Song, Dhanendra Tomar, Muniswamy Madesh, Annick Judenherc-Haouzi, Philippe Haouzi
In adult left ventricular mouse myocytes, exposure to sodium cyanide (NaCN) in the presence of glucose dose-dependently reduced contraction amplitude, with ~80% of maximal inhibitory effect attained at 100 µM. NaCN (100 µM) exposure for 10 min. significantly decreased contraction and intracellular Ca2+ concentration ([Ca2+]i)transient amplitudes, systolic but not diastolic [Ca2+]i, and maximal L-type Ca2+ current (ICa) amplitude: indicating acute alteration of [Ca2+]i homeostasis largely accounted for the observed excitation-contraction abnormalities...
February 8, 2018: Journal of Applied Physiology
https://www.readbyqxmd.com/read/29374044/inhibitory-effect-of-vascular-endothelial-growth-factor-on-the-slowly-activating-delayed-rectifier-potassium-current-in-guinea-pig-ventricular-myocytes
#6
Zhenhao Lin, Wenlu Xing, Chuanyu Gao, Xianpei Wang, Datun Qi, Guoyou Dai, Wen Zhao, Ganxin Yan
BACKGROUND: Vascular endothelial growth factor (VEGF) exerts a number of beneficial effects on ischemic myocardium via its angiogenic properties. However, little is known about whether VEGF has a direct effect on the electrical properties of cardiomyocytes. In the present study, we investigated the effects of different concentrations of VEGF on delayed rectifier potassium currents (IK) in guinea pig ventricular myocytes and their effects on action potential (AP) parameters. METHODS AND RESULTS: IK and AP were recorded by the whole-cell patch clamp method in ventricular myocytes...
January 26, 2018: Journal of the American Heart Association
https://www.readbyqxmd.com/read/29367102/effects-of-prasugrel-on-membrane-potential-and-contractile-activity-of-rat-ventricular-myocytes
#7
Murathan Kucuk, Murat Cenk Celen, Bilge Eren Yamasan, Selcuk Kucukseymen, Semir Ozdemir
BACKGROUND: Though prasugrel is one of the important P2Y12 inhibitors currently in use for antiplatelet therapy, its potential effects on contractility and electrical activity of ventricular myocytes have not yet been investigated. Hence this study was designed to study the impact of prasugrel on contractile function and membrane potential of isolated ventricular myocytes. METHODS: Freshly isolated rat ventricular myocytes were used in this study. Myocyte contraction was measured during electrical stimulation of cardiomyocytes and the action potential (AP) recordings were obtained with current clamp mode of the patch-clamp amplifier...
September 1, 2017: Pharmacological Reports: PR
https://www.readbyqxmd.com/read/29338006/a-model-for-cooperative-gating-of-l-type-ca2-channels-and-its-effects-on-cardiac-alternans-dynamics
#8
Daisuke Sato, Rose E Dixon, Luis F Santana, Manuel F Navedo
In ventricular myocytes, membrane depolarization during the action potential (AP) causes synchronous activation of multiple L-type CaV1.2 channels (LTCCs), which trigger the release of calcium (Ca2+) from the sarcoplasmic reticulum (SR). This results in an increase in intracellular Ca2+ (Cai) that initiates contraction. During pulsus alternans, cardiac contraction is unstable, going from weak to strong in successive beats despite a constant heart rate. These cardiac alternans can be caused by the instability of membrane potential (Vm) due to steep AP duration (APD) restitution (Vm-driven alternans), instability of Cai cycling (Ca2+-driven alternans), or both, and may be modulated by functional coupling between clustered CaV1...
January 16, 2018: PLoS Computational Biology
https://www.readbyqxmd.com/read/29326130/inward-rectifier-potassium-channels-kir2-x-and-caveolin-3-domain-specific-interaction-implications-for-purkinje-cell-dependent-ventricular-arrhythmias
#9
Ravi Vaidyanathan, Hanora Van Ert, Kazi T Haq, Stefano Morotti, Samuel Esch, Elise C McCune, Eleonora Grandi, Lee L Eckhardt
BACKGROUND: In human cardiac ventricle, IK1 is mainly comprised Kir2.1, but Kir2.2 and Kir2.3 heterotetramers occur and modulate IK1. Long-QT syndrome-9-associated CAV3 mutations cause decreased Kir2.1 current density, but Kir2.x heterotetramers have not been studied. Here, we determine the effect of long-QT syndrome-9-CAV3 mutation F97C on Kir2.x homo- and heterotetramers and model-associated arrhythmia mechanisms. METHODS AND RESULTS: Super-resolution microscopy, co-immunoprecipitation, cellular electrophysiology, on-cell Western blotting, and simulation of Purkinje and ventricular myocyte mathematical models were used...
January 2018: Circulation. Arrhythmia and Electrophysiology
https://www.readbyqxmd.com/read/29311162/differential-expression-and-remodeling-of-transient-outward-potassium-currents-in-human-left-ventricles
#10
Eric K Johnson, Steven J Springer, Wei Wang, Edward J Dranoff, Yan Zhang, Evelyn M Kanter, Kathryn A Yamada, Jeanne M Nerbonne
BACKGROUND: Myocardial, transient, outward currents, Ito, have been shown to play pivotal roles in action potential (AP) repolarization and remodeling in animal models. The properties and contribution of Ito to left ventricular (LV) repolarization in the human heart, however, are poorly defined. METHODS AND RESULTS: Whole-cell, voltage-clamp recordings, acquired at physiological (35°C to 37°C) temperatures, from myocytes isolated from the LV of nonfailing human hearts identified 2 distinct transient currents, Ito,fast (Ito,f) and Ito,slow (Ito,s), with significantly (P<0...
January 2018: Circulation. Arrhythmia and Electrophysiology
https://www.readbyqxmd.com/read/29306474/concealed-abnormal-atrial-phenotype-in-patients-with-brugada-syndrome-and-no-history-of-atrial-fibrillation
#11
Giulio Conte, Maria Luce Caputo, Paul G A Volders, Adrian Luca, Luca Mainardi, Ulrich Schotten, Valentina D A Corino, François Regoli, Stef Zeemering, Matthias Zink, Sasan Yazdani, Lukas Kappenberger, Tiziano Moccetti, Jean-Marc Vesin, Angelo Auricchio
OBJECTIVES: The electrocardiogram (ECG) of patients with BrS in sinus rhythm might reflect intrinsic atrial electrical abnormalities independent from any previous atrial fibrillation (AF). Aim of this study is to investigate the presence of P-wave abnormalities in patients with BrS and no history of AF, and to compare them with those displayed by patients with documented paroxysmal AF and by healthy subjects. METHODS: Continuous 5-min 16-lead ECG recordings in sinus rhythm were obtained from 72 participants: 32 patients with a type 1 Brugada ECG, 20 patients with a history of paroxysmal AF and 20 age-matched healthy subjects...
February 15, 2018: International Journal of Cardiology
https://www.readbyqxmd.com/read/29295576/intracellular-renin-inhibits-mitochondrial-permeability-transition-pore-via-activated-mitochondrial-extracellular-signal-regulated-kinase-erk-1-2-during-ischemia-in-diabetic-hearts
#12
Terumori Satoh, Masao Saotome, Hideki Katoh, Daishi Nonaka, Prottoy Hasan, Hideharu Hayashi, Yuichiro Maekawa
Although beneficial effects of non-secreting intracellular renin (ns-renin) against ischemia have been reported, the precise mechanism remains unclear. In this study, we investigated the roles of ns-renin and mitochondrial extracellular signal-related kinase (ERK) 1/2 on mitochondrial permeability transition pore (mPTP) opening during ischemia in diabetes mellitus (DM) hearts. When isolated hearts from Wistar rats (non-DM hearts) and Goto-Kakizaki rats (DM hearts) were subjected to ischemia for 70 min by left anterior descending coronary artery ligation, DM hearts exhibited higher left ventricular (LV) developed pressure and lower LV end-diastolic pressure than non-DM hearts, suggesting ischemic resistance...
December 25, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/29277286/the-relationship-between-the-s-wave-in-lead-1-and-recurrence-of-rvot-pvc-ablation
#13
Hacı Murat Güneş, Gültekin Günhan Demir, Oğuz Karaca, Filiz Kızılırmak Yılmaz, Ersin İbişoğlu, Tayyar Gökdeniz, Mehmet Onur Omaygenç, Ekrem Güler, Gamze Babur Güler, Ümeyir Savur, Beytullah Çakal, İrfan Barutçu, Fethi Kılıçaslan
BACKGROUND: Radiofrequency catheter ablation (CA) is a common non-pharmacological treatment option for ventricular premature contractions (PVCs) originating from right ventricular outflow tract (RVOT). In this study, we aimed to investigate the relationship between recurrence after CA for RVOT-PVC and S-wave in lead 1 that was shown to be associated with RVOT depolarization. METHODOLOGY: A total of 104 patients who were referred to our clinic for CA for idiopathic RVOT-PVC between 2012 and 2015years were enrolled...
December 14, 2017: Journal of Electrocardiology
https://www.readbyqxmd.com/read/29203397/pro-arrhythmic-effects-of-low-plasma-k-in-human-ventricle-an-illustrated-review
#14
REVIEW
Beatriz Trenor, Karen Cardona, Lucia Romero, Juan F Gomez, Javier Saiz, Sridharan Rajamani, Luiz Belardinelli, Wayne Giles
Potassium levels in the plasma, [K+]o, are regulated precisely under physiological conditions. However, increases (from approx. 4.5 to 8.0mM) can occur as a consequence of, e.g., endurance exercise, ischemic insult or kidney failure. This hyperkalemic modulation of ventricular electrophysiology has been studied extensively. Hypokalemia is also common. It can occur in response to diuretic therapy, following renal dialysis, or during recovery from endurance exercise. In the human ventricle, clinical hypokalemia (e...
November 24, 2017: Trends in Cardiovascular Medicine
https://www.readbyqxmd.com/read/29173399/basic-electrophysiologic-mechanisms-of-sudden-cardiac-death-caused-by-acute-myocardial-ischemia-and-infarction
#15
REVIEW
Andrew L Wit
Sudden cardiac death caused by acute ischemia results from electrophysiologic changes in myocardium deprived of its blood supply. These changes include a reduction in resting potential and phase 0 depolarization and an increase in intercellular resistivity that slow conduction, cause conduction block, and lead to reentrant excitation and ventricular fibrillation. Reperfusion of a coronary artery after a short period of occlusion leads to similar changes.
December 2017: Cardiac Electrophysiology Clinics
https://www.readbyqxmd.com/read/29166279/influence-of-long-term-oral-application-of-quinolones-on-the-ecg-curve-in-dogs
#16
A Cepiel, A Noszczyk-Nowak, A Cekiera, J Popiel, U Pasławska
The aim of the study was to analyse the influence of enrofloxacin and pradofloxacin administered orally for 14 days on the ECG in dogs. The ECG was performed before and after a 14 day period of quinolone administration. There was an increase in the QTc and the TpTe interval in the group treated with quinolones. QTc was prolonged by 24 ms (p=0.001). The TpTe interval was shortened, on average, by 6.55 ms (p=0.048). In the group treated with enrofloxacin, QTc was prolonged by 16.27 ms (p=0.006) and the TpTe interval was shortened by 9...
September 26, 2017: Polish Journal of Veterinary Sciences
https://www.readbyqxmd.com/read/29163179/in-silico-assessment-of-efficacy-and-safety-of-ikur-inhibitors-in-chronic-atrial-fibrillation-role-of-kinetics-and-state-dependence-of-drug-binding
#17
Nicholas Ellinwood, Dobromir Dobrev, Stefano Morotti, Eleonora Grandi
Current pharmacological therapy against atrial fibrillation (AF), the most common cardiac arrhythmia, is limited by moderate efficacy and adverse side effects including ventricular proarrhythmia and organ toxicity. One way to circumvent the former is to target ion channels that are predominantly expressed in atria vs. ventricles, such as KV1.5, carrying the ultra-rapid delayed-rectifier K+ current (IKur). Recently, we used an in silico strategy to define optimal KV1.5-targeting drug characteristics, including kinetics and state-dependent binding, that maximize AF-selectivity in human atrial cardiomyocytes in normal sinus rhythm (nSR)...
2017: Frontiers in Pharmacology
https://www.readbyqxmd.com/read/29135530/should-percussion-pacing-have-a-role-in-perioperative-advanced-cardiac-life-support-a-case-report
#18
Chris Giordano, Jordan Miller, Ilan Keidan
Percussion pacing involves using one's fist to repeatedly strike a patient's left sternal border in a rhythmic manner. The resulting increase in ventricular pressure can trigger myocardial depolarization and subsequent contraction. We describe the successful treatment of acute preoperative symptomatic sinus bradycardia with percussion pacing in a 63-year-old patient scheduled for placement of a gastric feeding tube after trauma involving spinal cord injury. Although no longer included in current advanced cardiovascular life support guidelines, percussion pacing may be a suitable alternative to chest compressions in multitrauma cases where the force of compressions could cause further complications...
November 9, 2017: A & A Case Reports
https://www.readbyqxmd.com/read/29128504/biophysical-comparison-of-sodium-currents-in-native-cardiac-myocytes-and-human-induced-pluripotent-stem-cell-derived-cardiomyocytes
#19
Robert J Goodrow, Suveer Desai, Jacqueline A Treat, Brian K Panama, Mayurika Desai, Vladislav V Nesterenko, Jonathan M Cordeiro
INTRODUCTION: Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) are used for safety pharmacology and to investigate genetic diseases affecting cardiac ion channels. It is unclear whether adult myocytes or hiPSC-CMs are the better platform for cardiac safety pharmacology. We examined the biophysical and molecular properties of INa in adult myocytes and hiPSC-CMs. METHODS: hiPSC-CMs were plated at low density. Atrial and ventricular cells were obtained from dog hearts...
November 8, 2017: Journal of Pharmacological and Toxicological Methods
https://www.readbyqxmd.com/read/29107282/the-autonomic-nervous-system-and-cardiac-glp-1-receptors-control-heart-rate-in-mice
#20
Laurie L Baggio, John R Ussher, Brent A McLean, Xiemin Cao, M Golam Kabir, Erin E Mulvihill, Alexandra S Mighiu, Hangjun Zhang, Andreas Ludwig, Randy J Seeley, Scott P Heximer, Daniel J Drucker
OBJECTIVES: Glucagon-like peptide-1 (GLP-1) is secreted from enteroendocrine cells and exerts a broad number of metabolic actions through activation of a single GLP-1 receptor (GLP-1R). The cardiovascular actions of GLP-1 have garnered increasing attention as GLP-1R agonists are used to treat human subjects with diabetes and obesity that may be at increased risk for development of heart disease. Here we studied mechanisms linking GLP-1R activation to control of heart rate (HR) in mice...
November 2017: Molecular Metabolism
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