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Ventricular depolarization

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https://www.readbyqxmd.com/read/29671257/glycogen-synthase-kinase-3%C3%AE-opens-mitochondrial-permeability-transition-pore-through-mitochondrial-hexokinase-ii-dissociation
#1
Takamitsu Tanaka, Masao Saotome, Hideki Katoh, Terumori Satoh, Prottoy Hasan, Hayato Ohtani, Hiroshi Satoh, Hideharu Hayashi, Yuichiro Maekawa
Accumulating evidence has revealed pivotal roles of glycogen synthase kinase-3β (GSK3β) inactivation on cardiac protection. Because the precise mechanisms of cardiac protection against ischemia/reperfusion (I/R) injury by GSK3β-inactivation remain elusive, we investigated the relationship between GSK3β-mediated mitochondrial hexokinase II (mitoHK-II; a downstream target of GSK3β) dissociation and mitochondrial permeability transition pore (mPTP) opening. In Langendorff-perfused hearts, GSK3β inactivation by SB216763 improved the left ventricular-developed pressure and retained mitoHK-II binding after I/R...
April 18, 2018: Journal of Physiological Sciences: JPS
https://www.readbyqxmd.com/read/29644942/postnatal-undernutrition-in-mice-causes-cardiac-arrhythmogenesis-which-is-exacerbated-when-pharmacologically-stressed
#2
J R Visker, D P Ferguson
Growth restriction caused by postnatal undernutrition increases risk for cardiovascular disease in adulthood with the potential to induce arrhythmogenesis. Thus, the purpose was to determine if undernutrition during development produced arrhythmias at rest and when stressed with dobutamine in adulthood. Mouse dams were fed (CON: 20% protein), or low-protein (LP: 8%) diet before mating. A cross-fostering model was used where pups nursed by dams fed LP diet in early [EUN; postnatal day (PN) 1-10], late (LUN; PN11-21) and whole (PUN; 1-21) phases of postnatal life...
April 12, 2018: Journal of Developmental Origins of Health and Disease
https://www.readbyqxmd.com/read/29622988/outflow-tract-ventricular-premature-beats-ablation-in-the-presence-or-absence-of-structural-heart-disease-technical-considerations-and-clinical-outcomes
#3
Haitham Badran, Rania Samir, Mohamed Amin
Background: Premature ventricular beats (PVBs) are early depolarization of the myocardium originating in the ventricle. In case of very frequent PVBs, patients are severely symptomatic with impaired quality of life and are at risk of pre-syncope, syncope, heart failure, and sudden cardiac death particularly in the presence of structural heart disease. Ventricular outflow tracts are the most common sites of origin of idiopathic PVBs especially in patients without structural heart disease...
December 2017: The Egyptian heart journal: (EHJ): official bulletin of the Egyptian Society of Cardiology
https://www.readbyqxmd.com/read/29603116/methylene-blue-counteracts-h-2-s-induced-cardiac-ion-channel-dysfunction-and-atp-reduction
#4
Joseph Y Cheung, JuFang Wang, Xue-Qian Zhang, Jianliang Song, John M Davidyock, Fabian Jana Prado, Santhanam Shanmughapriya, Alison M Worth, Muniswamy Madesh, Annick Judenherc-Haouzi, Philippe Haouzi
We have previously demonstrated that methylene blue (MB) counteracts the effects of hydrogen sulfide (H2 S) cardiotoxicity by improving cardiomyocyte contractility and intracellular Ca2+ homeostasis disrupted by H2 S poisoning. In vivo, MB restores cardiac contractility severely depressed by sulfide and protects against arrhythmias, ranging from bundle branch block to ventricular tachycardia or fibrillation. To dissect the cellular mechanisms by which MB reduces arrhythmogenesis and improves bioenergetics in myocytes intoxicated with H2 S, we evaluated the effects of H2 S on resting membrane potential (Em ), action potential (AP), Na+ /Ca2+ exchange current (INaCa ), depolarization-activated K+ currents and ATP levels in adult mouse cardiac myocytes and determined whether MB could counteract the toxic effects of H2 S on myocyte electrophysiology and ATP...
March 30, 2018: Cardiovascular Toxicology
https://www.readbyqxmd.com/read/29593570/distinct-ecg-phenotypes-identified-in-hypertrophic-cardiomyopathy-using-machine-learning-associate-with-arrhythmic-risk-markers
#5
Aurore Lyon, Rina Ariga, Ana Mincholé, Masliza Mahmod, Elizabeth Ormondroyd, Pablo Laguna, Nando de Freitas, Stefan Neubauer, Hugh Watkins, Blanca Rodriguez
Aims: Ventricular arrhythmia triggers sudden cardiac death (SCD) in hypertrophic cardiomyopathy (HCM), yet electrophysiological biomarkers are not used for risk stratification. Our aim was to identify distinct HCM phenotypes based on ECG computational analysis, and characterize differences in clinical risk factors and anatomical differences using cardiac magnetic resonance (CMR) imaging. Methods: High-fidelity 12-lead Holter ECGs from 85 HCM patients and 38 healthy volunteers were analyzed using mathematical modeling and computational clustering to identify phenotypic subgroups...
2018: Frontiers in Physiology
https://www.readbyqxmd.com/read/29593564/dynamic-action-potential-restitution-contributes-to-mechanical-restitution-in-right-ventricular-myocytes-from-pulmonary-hypertensive-rats
#6
Matthew E L Hardy, Eleftheria Pervolaraki, Olivier Bernus, Ed White
We investigated the steepened dynamic action potential duration (APD) restitution of rats with pulmonary artery hypertension (PAH) and right ventricular (RV) failure and tested whether the observed APD restitution properties were responsible for negative mechanical restitution in these myocytes. PAH and RV failure were provoked in male Wistar rats by a single injection of monocrotaline (MCT) and compared with saline-injected animals (CON). Action potentials were recorded from isolated RV myocytes at stimulation frequencies between 1 and 9 Hz...
2018: Frontiers in Physiology
https://www.readbyqxmd.com/read/29578202/the-impact-of-the-left-ventricular-pacing-polarity-and-localization-during-cardiac-resynchronization-therapy-on-depolarization-and-repolarization-parameters
#7
Emin Evren Özcan, Ali Öztürk, Erdem Özel, Ömer Senarslan, Bela Merkely, Laszlo Geller
OBJECTIVE: Reversal of myocardial activation sequence during cardiac resynchronization therapy (CRT) may increase the transmural dispersion of repolarization (TDR), which may lead to ventricular arrhythmias. Quadripolar left ventricular (LV) leads offer 10 different pacing configurations. However, little is known about the role of pacing polarity on repolarization patterns. Our study aimed to investigate the impact of LV pacing polarity on depolarization and repolarization parameters in the same substrate in the same patient group...
March 21, 2018: Anatolian Journal of Cardiology
https://www.readbyqxmd.com/read/29576852/zp2495-protects-against-myocardial-ischemia-reperfusion-injury-in-diabetic-mice-through-improvement-of-cardiac-metabolism-and-mitochondrial-function-the-possible-involvement-of-ampk-foxo3a-signal-pathway
#8
Shuang Li, Hao Wu, Dong Han, Mingming Zhang, Na Li, Weihua Yu, Dongdong Sun, Zhongchan Sun, Sai Ma, Erhe Gao, Congye Li, Min Shen, Feng Cao
Coronary heart disease patients with type 2 diabetes were subject to higher vulnerability for cardiac ischemia-reperfusion (I/R) injury. This study was designed to evaluate the impact of ZP2495 (a glucagon-GLP-1 dual-agonist) on cardiac function and energy metabolism after myocardial I/R injury in db/db mice with a focus on mitochondrial function. C57BLKS/J-lepr+ /lepr+ (BKS) and db/db mice received 4-week treatment of glucagon, ZP131 (GLP-1 receptor agonist), or ZP2495, followed by cardiac I/R injury. The results showed that cardiac function, cardiac glucose metabolism, cardiomyocyte apoptosis, cardiac mitochondrial morphology, and energetic transition were improved or ameliorated by ZP2495 to a greater extent than that of glucagon and ZP131...
2018: Oxidative Medicine and Cellular Longevity
https://www.readbyqxmd.com/read/29568272/four-trpm4-cation-channel-mutations-found-in-cardiac-conduction-diseases-lead-to-altered-protein-stability
#9
Beatrice Bianchi, Lijo Cherian Ozhathil, Argelia Medeiros-Domingo, Michael H Gollob, Hugues Abriel
Transient receptor potential melastatin member 4 (TRPM4), a non-selective cation channel, mediates cell membrane depolarization in immune response, insulin secretion, neurological disorders, and cancer. Pathological variants in TRPM4 gene have been linked to several cardiac phenotypes such as complete heart block (CHB), ventricular tachycardia, and Brugada syndrome (BrS). Despite recent findings regarding the functional implications of TRPM4 in cardiac diseases, the molecular and cellular mechanisms leading to altered conduction are poorly understood...
2018: Frontiers in Physiology
https://www.readbyqxmd.com/read/29531045/complex-electrophysiological-remodeling-in-postinfarction-ischemic-heart-failure
#10
Bence Hegyi, Julie Bossuyt, Leigh G Griffiths, Rafael Shimkunas, Zana Coulibaly, Zhong Jian, Kristin N Grimsrud, Claus S Sondergaard, Kenneth S Ginsburg, Nipavan Chiamvimonvat, Luiz Belardinelli, András Varró, Julius G Papp, Piero Pollesello, Jouko Levijoki, Leighton T Izu, W Douglas Boyd, Tamás Bányász, Donald M Bers, Ye Chen-Izu
Heart failure (HF) following myocardial infarction (MI) is associated with high incidence of cardiac arrhythmias. Development of therapeutic strategy requires detailed understanding of electrophysiological remodeling. However, changes of ionic currents in ischemic HF remain incompletely understood, especially in translational large-animal models. Here, we systematically measure the major ionic currents in ventricular myocytes from the infarct border and remote zones in a porcine model of post-MI HF. We recorded eight ionic currents during the cell's action potential (AP) under physiologically relevant conditions using self AP-clamp sequential dissection...
March 27, 2018: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/29514831/cardiac-kir2-1-and-na-v-1-5-channels-traffic-together-to-the-sarcolemma-to-control-excitability
#11
Daniela Ponce-Balbuena, Guadalupe Guerrero-Serna, Carmen R Valdivia, Ricardo Caballero, F J Díez-Guerra, Eric N Jiménez-Vázquez, Rafael J Ramirez, Andre Monteiro da Rocha, Todd J Herron, Katherine F Campbell, B C Willis, Francisco J Alvarado, Manuel Zarzoso, Kuljeet Kaur, Marta Pérez-Hernández, Marcos Matamoros, Héctor H Valdivia, Eva Delpón, José Jalife
<u>Rationale:</u> In cardiomyocytes, NaV 1.5 and Kir2.1 channels interact dynamically as part of membrane bound macromolecular complexes. <u>Objective:</u> To test whether NaV 1.5 and Kir2.1 preassemble during early forward trafficking and travel together to common membrane microdomains. <u>Methods and Results:</u> In patch-clamp experiments, co-expression of trafficking deficient mutants Kir2.1Δ314-315 or Kir2.1R44A/R46A with wildtype (WT) NaV 1.5WT in heterologous cells reduced INa , compared to NaV 1...
March 7, 2018: Circulation Research
https://www.readbyqxmd.com/read/29493400/qtc-%C3%A4-nterval-is-prolonged-in-wilson-s-disease-with-neurologic-%C3%A4-nvolvement
#12
Semi Ozturk, Ahmet Seyfeddin Gurbuz, Suleyman Cagan Efe, Raim Iliaz, Mutse Banzragch, Kadir Demir
Background Neurologic and liver involvement in Wilson's disease (WD) is well-documented, however, few reports demonstrated cardiac involvement. Tpe and Tpe/QT are new measures of ventricular repolarization which were recently suggested as predictor of arrythmogenesis. We aimed to evaluate ventricular depolarization and repolarization parameters including QT, QTc, Tpe intervals, Tpe/QT, Tpe/QTc ratios, and QT dispersion (QTd) in patients with WD. Materials and methods Thirty-five patients with WD and 30 healthy controls were included in the study...
March 1, 2018: Acta Clinica Belgica
https://www.readbyqxmd.com/read/29457789/a-common-variant-alters-scn5a-mir-24-interaction-and-associates-with-heart-failure-mortality
#13
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...
March 1, 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
#14
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
#15
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
#16
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
#17
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
#18
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
#19
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...
February 2018: 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
#20
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 2018: PLoS Computational Biology
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