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("ryanodine receptor" OR "ryr" OR "ryr2") AND ("heart" OR "cardiac")

Xiao-Dong Zhang, Zana A Coulibaly, Wei Chun Chen, Hannah A Ledford, Jeong Han Lee, Padmini Sirish, Gu Dai, Zhong Jian, Frank Chuang, Ingrid Brust-Mascher, Ebenezer N Yamoah, Ye Chen-Izu, Leighton T Izu, Nipavan Chiamvimonvat
Small-conductance Ca2+ -activated K+ (SK) channels regulate the excitability of cardiomyocytes by integrating intracellular Ca2+ and membrane potentials on a beat-to-beat basis. The inextricable interplay between activation of SK channels and Ca2+ dynamics suggests the pathology of one begets another. Yet, the exact mechanistic underpinning for the activation of cardiac SK channels remains unaddressed. Here, we investigated the intracellular Ca2+ microdomains necessary for SK channel activation. SK currents coupled with Ca2+ influx via L-type Ca2+ channels (LTCCs) continued to be elicited after application of caffeine, ryanodine or thapsigargin to deplete SR Ca2+ store, suggesting that LTCCs provide the immediate Ca2+ microdomain for the activation of SK channels in cardiomyocytes...
March 16, 2018: Scientific Reports
David J Tester, Leonie C H Wong, Pritha Chanana, Amie Jaye, Jared M Evans, David R FitzPatrick, Margaret J Evans, Peter Fleming, Iona Jeffrey, Marta C Cohen, Jacob Tfelt-Hansen, Michael A Simpson, Elijah R Behr, Michael J Ackerman
BACKGROUND: Sudden infant death syndrome (SIDS) is a leading cause of postneonatal mortality. Genetic heart diseases (GHDs) underlie some cases of SIDS. OBJECTIVES: This study aimed to determine the spectrum and prevalence of GHD-associated mutations as a potential monogenic basis for SIDS. METHODS: A cohort of 419 unrelated SIDS cases (257 male; average age 2.7 ± 1.9 months) underwent whole exome sequencing and a targeted analysis of 90 GHD-susceptibility genes...
March 20, 2018: Journal of the American College of Cardiology
Uma Mahesh R Avula, Jonathan J Hernandez, Masatoshi Yamazaki, Carmen R Valdivia, Antony Chu, Alvaro Rojas-Pena, Kuljeet Kaur, Roberto Ramos-Mondragón, Justus M Anumonwo, Stanley Nattel, Héctor H Valdivia, Jérôme Kalifa
BACKGROUND: The mechanisms underlying spontaneous atrial fibrillation (AF) associated with atrial ischemia/infarction are incompletely elucidated. Here, we investigate the mechanisms underlying spontaneous AF in an ovine model of left atrial myocardial infarction (LAMI). METHODS AND RESULTS: LAMI was created by ligating the atrial branch of the left anterior descending coronary artery. ECG loop recorders were implanted to monitor AF episodes. In 7 sheep, dantrolene-a ryanodine receptor blocker-was administered in vivo during the 8-day observation period (LAMI-D, 2...
March 2018: Circulation. Arrhythmia and Electrophysiology
Alexey E Lyashkov, Joachim Beahr, Edward G Lakatta, Yael Yaniv, Victor A Maltsev
Recent data suggest that cardiac pacemaker cell function is determined by numerous time-, voltage-, and Ca-dependent interactions of cell membrane electrogenic proteins (M-clock) and intracellular Ca cycling proteins (Ca-clock), forming a coupled-clock system. Many aspects of the coupled-clock system, however, remain underexplored. The key players of the system are Ca release channels (ryanodine receptors), generating local Ca releases (LCRs) from sarcoplasmic reticulum, electrogenic Na/Ca exchanger (NCX) current, and L-type Ca current (ICaL )...
March 13, 2018: Biophysical Journal
Tian Li, Yafeng Shen, Li Su, Xiaoyan Fan, Fangxing Lin, Xuting Ye, Dianer Ding, Ying Tang, Yang Yongji, Changhai Lei, Shi Hu
Post-ischemic heart failure is a major cause of death worldwide. Reperfusion of infarcted heart tissue after myocardial infarction has been an important medical intervention to improve outcomes. However, disturbances in Ca2+ and redox homeostasis at the cellular level caused by ischemia/reperfusion remain major clinical challenges. In this study, we investigated the potential of adeno-associated virus (AAV)-9-mediated cardiac expression of a Type-2 ryanodine receptor (RyR2) degradation-associated gene, Presenilin 1 (PSEN1), to combat post-ischemic heart failure...
March 9, 2018: Journal of Drug Targeting
Xudong Chen, Yundi Feng, Yunlong Huo, Wenchang Tan
Ca2+ sparks and Ca2+ quarks, arising from clustered and rogue ryanodine receptors (RyRs), are significant Ca2+ release events from the junctional sarcoplasmic reticulum (JSR). Based on the anomalous subdiffusion of Ca2+ in the cytoplasm, a mathematical model was developed to investigate the effects of rogue RyRs on Ca2+ sparks in cardiac myocytes. Ca2+ quarks and sparks from the stochastic opening of rogue and clustered RyRs are numerically reproduced and agree with experimental measurements. It is found that the stochastic opening Ca2+ release units (CRUs) of clustered RyRs are regulated by free Ca2+ concentration in the JSR lumen (i...
February 2018: Royal Society Open Science
Elisa Bovo, Stefan R Mazurek, Aleksey V Zima
Defective Ca2+ regulation plays a key role in the blunted force-frequency response in heart failure (HF). Since HF is commonly associated with oxidative stress, we studied whether oxidation of ryanodine receptor (RyR2) contributes to this defect. In control ventricular myocytes, oxidative stress induced formation of disulfide bonds between RyR2 subunits: intersubunit cross-linking (XL). Western blot analysis and Ca2+ imaging revealed a strong positive correlation between RyR2 XL and sarcoplasmic reticulum (SR) Ca2+ leak...
March 2, 2018: Pflügers Archiv: European Journal of Physiology
Jozef Klučka, Tomáš Juřenčák, Petr Štourač, Pavel Vít, Vladimíra Foralová, Iva Synková
Out-of-hospital cardiac arrest in pediatric population is rare and predominantly has respiratory aetiology. Authors present the relatively unique case of out-of hospital cardiac arrest in 5-years old pediatric patient due to ventricular fibrillation (VF) as the initial rhythm during the advanced life support. The patient was resuscitated by his parents and the initial rhythm was VF. After defibrillation the patient was admitted to the pediatric intensive care were another two episodes of VF was detected and treated...
February 28, 2018: Pediatric Emergency Care
Jing Xiong, Xijun Liu, Yunyun Gong, Peng Zhang, Sujing Qiang, Qian Zhao, Rong Guo, Yunyun Qian, Lipeng Wang, Li Zhu, Ruiwu Wang, Zhiyuan Hao, Han Wen, Jingying Zhang, Kai Tang, Wang-Fu Zang, Zhiguang Yuchi, Haijun Chen, S R Wayne Chen, Wenjun Zheng, Shi-Qiang Wang, Ya-Wei Xu, Zheng Liu
Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a condition that is characterized by an abnormal heart rhythm in response to physical or emotional stress. The majority CPVT patients carry mutations in the RYR2 gene that encodes the calcium release channel/ryanodine receptor (RyR2) in cardiomyocytes. The pathogenic mechanisms that account for the clinical phenotypes of CPVT are still elusive. We have identified a de novo mutation, A165D, from a CPVT patient. We found that CPVT phenotypes are recapitulated in A165D knock-in mice...
February 22, 2018: Journal of Molecular and Cellular Cardiology
Gaetano Santulli, Daniel Lewis, Amedee des Georges, Andrew R Marks, Joachim Frank
Ryanodine receptors (RyRs) are ubiquitous intracellular calcium (Ca2+ ) release channels required for the function of many organs including heart and skeletal muscle, synaptic transmission in the brain, pancreatic beta cell function, and vascular tone. In disease, defective function of RyRs due either to stress (hyperadrenergic and/or oxidative overload) or genetic mutations can render the channels leaky to Ca2+ and promote defective disease-causing signals as observed in heat failure, muscular dystrophy, diabetes mellitus, and neurodegerative disease...
2018: Sub-cellular Biochemistry
Kenji Suita, Takayuki Fujita, Wenqian Cai, Yuko Hidaka, Huiling Jin, Rajesh Prajapati, Masanari Umemura, Utako Yokoyama, Motohiko Sato, Björn C Knollmann, Satoshi Okumura, Yoshihiro Ishikawa
Sympathetic activation causes clinically important arrhythmias including atrial fibrillation (AF) and ventricular tachyarrhythmia. Although the usefulness of β-adrenergic receptor blockade therapy is widely accepted, its multiple critical side effects often prevent its initiation or continuation. The aim of this study is to determine the advantages of vidarabine, an adenylyl cyclase (AC)-targeted anti-sympathetic agent, as an alternative treatment for arrhythmia. We found that vidarabine, which we identified as a cardiac AC inhibitor, consistently shortens AF duration and reduces the incidence of sympathetic activation-induced ventricular arrhythmias...
February 16, 2018: Pflügers Archiv: European Journal of Physiology
Daniel J Flores, ThuyVy Duong, Luke O Brandenberger, Apratim Mitra, Aditya Shirali, John C Johnson, Danielle Springer, Audrey Noguchi, Zu-Xi Yu, Steven N Ebert, Andreas Ludwig, Bjorn C Knollmann, Mark D Levin, Karl Pfeifer
Cardiac calsequestrin (Casq2) associates with the Ryanodine Receptor 2 channel in the junctional sarcoplasmic reticulum to regulate Ca2+ release into the cytoplasm. Patients carrying mutations in CASQ2 display low resting heart rates under basal conditions and stress-induced polymorphic ventricular tachycardia (CPVT). In this study we generate and characterize novel conditional deletion and conditional rescue mouse models to test the influence of developmental programs on the heart rate and CPVT phenotypes...
February 14, 2018: Human Molecular Genetics
Seung Min Baek, Hyun Chung, Mi Kyoung Song, Eun Jung Bae, Gi Beom Kim, Chung Il Noh
BACKGROUND AND OBJECTIVES: Multifocal atrial tachycardia (MAT), in general, has a favorable outcome. However, there are insufficient data regarding MAT in a pediatric population. This study sought to determine the clinical course of MAT and identify potential prognostic factors. METHODS: The medical records of MAT patients from 1997-2015 were reviewed. The arrhythmia control rate and factors for unfavorable outcomes were assessed and compared to those in the literature...
February 2018: Korean Circulation Journal
Michelle L Munro, Xin Shen, Marie Ward, Peter N Ruygrok, David J Crossman, Christian Soeller
Heart failure (HF) is defined by compromised contractile function and is associated with changes in excitation-contraction (EC) coupling and cardiomyocyte organisation. Tissue level changes often include fibrosis, while changes within cardiomyocytes often affect structures critical to EC coupling, including the ryanodine receptor (RyR), the associated protein junctophilin-2 (JPH2) and the transverse tubular system architecture. Using a novel approach, we aimed to directly correlate the influence of structural alterations with force development in ventricular trabeculae from failing human hearts...
February 13, 2018: Scientific Reports
Gina Sánchez, Felipe Araneda, Juan Pedro Peña, José Pablo Finkelstein, Jaime A Riquelme, Luis Montecinos, Genaro Barrientos, Paola Llanos, Zully Pedrozo, Matilde Said, Ricardo Bull, Paulina Donoso
Ventricular arrhythmias are a common cause of sudden cardiac death, and their occurrence is higher in obese subjects. Abnormal gating of ryanodine receptors (RyR2), the calcium release channels of the sarcoplasmic reticulum, can produce ventricular arrhythmias. Since obesity promotes oxidative stress and RyR2 are redox-sensitive channels, we investigated whether the RyR2 activity was altered in obese mice. Mice fed a high fat diet (HFD) became obese after eight weeks and exhibited a significant increase in the occurrence of ventricular arrhythmias...
February 10, 2018: International Journal of Molecular Sciences
Kazuaki Miyata, Seiko Ohno, Hideki Itoh, Minoru Horie
Background Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a lethal inherited disease characterized by ventricular arrhythmias induced by physical exercise or emotional stress. The major cause of CPVT is mutations in RYR2, which encodes the cardiac ryanodine receptor channel. Recent advances in sequencing technology have yielded incidental findings of RYR2 variants in other cardiac diseases. Analyzing the characteristics of RYR2 variants related to CPVT will be useful for differentiation from those related to other cardiac diseases...
February 9, 2018: Internal Medicine
Shigehiko Nishimura, Takeshi Yamamoto, Yoshihide Nakamura, Michiaki Kohno, Yoriomi Hamada, Yoko Sufu, Go Fukui, Takuma Nanno, Hironori Ishiguchi, Takayoshi Kato, Xiaojuan Xu, Makoto Ono, Tetsuro Oda, Shinichi Okuda, Shigeki Kobayashi, Masafumi Yano
BACKGROUND: Ryanodine receptor (RyR2) is known to be a causal gene of catecholaminergic polymorphic ventricular tachycardia (CPVT) as an important inherited disease. Some of the human CPVT-associated mutations were found in a domain (4026-4172), which has EF hand motifs; so-called calmodulin (CaM)-like domain (CaMLD). OBJECTIVE: To investigate the underlying mechanism by which CPVT is induced with mutation at CaMLD. METHODS: We newly generated N4103K/+ knock-in (KI) mice model...
February 7, 2018: Heart Rhythm: the Official Journal of the Heart Rhythm Society
Shinichi Okuda, Yoko Sufu-Shimizu, Takayoshi Kato, Masakazu Fukuda, Shigehiko Nishimura, Tetsuro Oda, Shigeki Kobayashi, Takeshi Yamamoto, Sachio Morimoto, Masafumi Yano
AIMS: Cardiac Troponin T (TnT) mutation-linked familial hypertrophic cardiomyopathy (FHC) is known to cause sudden cardiac death at a young age. Here, we investigated the role of the Ca2+ release channel of the cardiac sarcoplasmic reticulum (SR), ryanodine receptor (RyR2), in the pathogenic mechanism of lethal arrhythmia in FHC-related TnT-mutated transgenic mice (TG; TnT-delta160E). METHODS AND RESULTS: In TG cardiomyocytes, the Ca2+ spark frequency (SpF) was much higher than that in non-TG cardiomyocytes...
January 31, 2018: Biochemical and Biophysical Research Communications
Alexander Kondrashov, Minh Duc Hoang, James Smith, Jamie Bhagwan, Gary Duncan, Diogo Mosqueira, Maria Munoz, Nguyen T N Vo, Chris Denning
Modelling disease with hPSCs is hindered because the impact on cell phenotype from genetic variability between individuals can be greater than from the pathogenic mutation. While 'footprint-free' Cas9/CRISPR editing solves this issue, existing approaches are inefficient or lengthy. Here, a simplified PiggyBac strategy shortened hPSC editing by 2 weeks and required one round of clonal expansion and genotyping rather than two, with similar efficiencies to the longer conventional process. Success was shown across 4 cardiac-associated loci (ADRB2, GRK5, RYR2, ACTC1) by genomic cleavage and editing efficiencies of 8-93% and 8-67%, respectively, including mono- and/or bi-allelic events...
February 5, 2018: Stem Cells and Development
Vilmos Zsolnay, Michael Fill, Dirk Gillespie
In muscle, Ca2+ release from the sarcoplasmic reticulum (SR) into the cytosol is mediated through the ryanodine receptors (RyRs) and sustained by countercurrents that keep the SR membrane potential near 0 mV. Likewise, Ca2+ reuptake by the sarco/endoplasmic reticulum Ca2+ ATPase pump requires countercurrent. Although evidence has suggested that TRIC K+ channels and/or RyR K+ influx provide these countercurrents, the exact sources have not yet been determined. We used an equivalent circuit compartment model of a cardiac SR, the surrounding cytosol, and the dyadic cleft to probe the sources of countercurrent during a complete cardiac cycle...
January 23, 2018: Biophysical Journal
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