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- Title:
Cardiomyocyte-Specific STIM1 (Stromal Interaction Molecule 1) Depletion in the Adult Heart Promotes the Development of Arrhythmogenic Discordant Alternans.
- Document type:
- Article; Journal Article
- Author(s):
- Cacheux, Marine; Strauss, Benjamin; Raad, Nour; Ilkan, Zeki; Hu, Jun; Benard, Ludovic; Feske, Stefan; Hulot, Jean-Sebastien; Akar, Fadi G
- Abstract:
- BACKGROUND: STIM1 (stromal interaction molecule 1) is a calcium (Ca2+) sensor that regulates cardiac hypertrophy by triggering store-operated Ca2+ entry. Because STIM1 binding to phospholamban increases sarcoplasmic reticulum Ca2+ load independent of store-operated Ca2+ 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 STIM1flox/flox-Cretg/- (STIM1-KD) and littermate controls for STIM1flox/flox (referred to as STIM1-Ctl) and for Cretg/- 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.
- Journal title abbreviation:
- Circ Arrhythm Electrophysiol
- Year:
- 2019
- Journal volume:
- 12
- Journal issue:
- 11
- Fulltext / DOI:
- doi:10.1161/CIRCEP.119.007382
- Pubmed ID:
- http://view.ncbi.nlm.nih.gov/pubmed/31726860
- Print-ISSN:
- 1941-3149
- TUM Institution:
- I. Medizinische Klinik und Poliklinik (Kardiologie)
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