ArticleCirculation research2014
Hyperphosphorylation of RyRs underlies triggered activity in transgenic rabbit model of LQT2 syndrome.
Article in Circulation research, 2014. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 47 papers.
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47 citing papers in PubMed, 70 citations in OpenAlex.
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- Activation of small conductance CaThe Journal of physiology · 2023Article
- Electromechanical reciprocity and arrhythmogenesis in long-QT syndrome and beyond.European heart journal · 2022Review
- Preserved cardiac performance and adrenergic response in a rabbit model with decreased ryanodine receptor 2 expression.Journal of molecular and cellular cardiology · 2022Article
- Ero1α-Dependent ERp44 Dissociation From RyR2 Contributes to Cardiac Arrhythmia.Circulation research · 2022Article
- Cardiomyocyte NaBasic research in cardiology · 2021Article
- MCU overexpression evokes disparate dose-dependent effects on mito-ROS and spontaneous CaAmerican journal of physiology. Heart and circulatory physiology · 2021Article
- The role of calcium homeostasis remodeling in inherited cardiac arrhythmia syndromes.Pflugers Archiv : European journal of physiology · 2021Review
- Three-Week-Old Rabbit Ventricular Cardiomyocytes as a Novel System to Study Cardiac Excitation and EC Coupling.Frontiers in physiology · 2021Article
- Association Between Dynamic Change of QT Interval and Long-Term Cardiovascular Outcomes: A Prospective Cohort Study.Frontiers in cardiovascular medicine · 2021Article
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Authors and funding
14 authors at 2 institutions in 1 country.
Funding
Abstract
rationaleLoss-of-function mutations in human ether go-go (HERG) potassium channels underlie long QT syndrome type 2 (LQT2) and are associated with fatal ventricular tachyarrhythmia. Previously, most studies focused on plasma membrane-related pathways involved in arrhythmogenesis in long QT syndrome, whereas proarrhythmic changes in intracellular Ca(2+) handling remained unexplored.
objectiveWe investigated the remodeling of Ca(2+) homeostasis in ventricular cardiomyocytes derived from transgenic rabbit model of LQT2 to determine whether these changes contribute to triggered activity in the form of early after depolarizations (EADs). METHODS AND
resultsConfocal Ca(2+) imaging revealed decrease in amplitude of Ca(2+) transients and sarcoplasmic reticulum Ca(2+) content in LQT2 myocytes. Experiments using sarcoplasmic reticulum-entrapped Ca(2+) indicator demonstrated enhanced ryanodine receptor (RyR)-mediated sarcoplasmic reticulum Ca(2+) leak in LQT2 cells. Western blot analyses showed increased phosphorylation of RyR in LQT2 myocytes versus controls. Coimmunoprecipitation experiments demonstrated loss of protein phosphatases type 1 and type 2 from the RyR complex. Stimulation of LQT2 cells with β-adrenergic agonist isoproterenol resulted in prolongation of the plateau of action potentials accompanied by aberrant Ca(2+) releases and EADs, which were abolished by inhibition of Ca(2+)/calmodulin-dependent protein kinase type 2. Computer simulations showed that late aberrant Ca(2+) releases caused by RyR hyperactivity promote EADs and underlie the enhanced triggered activity through increased forward mode of Na(+)/Ca(2+) exchanger type 1.
conclusionsHyperactive, hyperphosphorylated RyRs because of reduced local phosphatase activity enhance triggered activity in LQT2 syndrome. EADs are promoted by aberrant RyR-mediated Ca(2+) releases that are present despite a reduction of sarcoplasmic reticulum content. Those releases increase forward mode Na(+)/Ca(2+) exchanger type 1, thereby slowing repolarization and enabling L-type Ca(2+) current reactivation.
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