Cardiomyocyte-Specific STIM1 (Stromal Interaction Molecule 1) Depletion in the Adult Heart Promotes the Development of Arrhythmogenic Discordant Alternans - Université Paris Cité Accéder directement au contenu
Article Dans Une Revue Circulation. Arrhythmia and electrophysiology Année : 2019

Cardiomyocyte-Specific STIM1 (Stromal Interaction Molecule 1) Depletion in the Adult Heart Promotes the Development of Arrhythmogenic Discordant Alternans

Résumé

Background: STIM1 (stromal interaction molecule 1) is a calcium (Ca 2+ ) sensor that regulates cardiac hypertrophy by triggering store-operated Ca 2+ entry. Because STIM1 binding to phospholamban increases sarcoplasmic reticulum Ca 2+ load independent of store-operated Ca 2+ entry, we hypothesized that it controls electrophysiological function and arrhythmias in the adult heart. Methods: Inducible myocyte-restricted STIM1-KD (STIM1 knockdown) was achieved in adult mice using an αMHC (α-myosin heavy chain)-MerCreMer system. Mechanical and electrophysiological properties were examined using echocardiography in vivo and optical action potential (AP) mapping ex vivo in tamoxifen-induced STIM1 flox/flox -Cre tg /− (STIM1-KD) and littermate controls for STIM1 flox/flox (referred to as STIM1-Ctl) and for Cre tg/− without STIM deletion (referred to as Cre-Ctl). Results: STIM1-KD mice (N=23) exhibited poor survival compared with STIM1-Ctl (N=22) and Cre-Ctl (N=11) with >50% mortality after only 8-days of cardiomyocyte-restricted STIM1-KD. STIM1-KD but not STIM1-Ctl or Cre-Ctl hearts exhibited a proclivity for arrhythmic behavior, ranging from frequent ectopy to pacing-induced ventricular tachycardia/ventricular fibrillation (VT/VF). Examination of the electrophysiological substrate revealed decreased conduction velocity and increased AP duration (APD) heterogeneity in STIM1-KD. These features, however, were comparable in VT/VF(+) and VT/VF(−) hearts. We also uncovered a marked increase in the magnitude of APD alternans during rapid pacing, and the emergence of a spatially discordant alternans profile in STIM1-KD hearts. Unlike conduction velocity slowing and APD heterogeneity, the magnitude of APD alternans was greater (by 80%, P <0.05) in VT/VF(+) versus VT/VF(−) STIM1-KD hearts. Detailed phase mapping during the initial beats of VT/VF identified one or more rotors that were localized along the nodal line separating out-of-phase alternans regions. Conclusions: In an adult murine model with inducible and myocyte-specific STIM1 depletion, we demonstrate for the first time the regulation of spatially discordant alternans by STIM1. Early mortality in STIM1-KD mice is likely related to enhanced susceptibility to VT/VF secondary to discordant APD alternans.
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Dates et versions

hal-04050705 , version 1 (29-03-2023)

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Marine Cacheux, Benjamin Strauss, Nour Raad, Zeki Ilkan, Jun Hu, et al.. Cardiomyocyte-Specific STIM1 (Stromal Interaction Molecule 1) Depletion in the Adult Heart Promotes the Development of Arrhythmogenic Discordant Alternans. Circulation. Arrhythmia and electrophysiology, 2019, 12 (11), ⟨10.1161/CIRCEP.119.007382⟩. ⟨hal-04050705⟩
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