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Updated: May 13, 2026
Isolation and Cryopreservation of Neonatal Rat Cardiomyocytes
Published on: April 9, 2015
Stroma cell-derived factor-1α signaling enhances calcium transients and beating frequency in rat neonatal
Ielham Hadad1, Alex Veithen, Jean-Yves Springael
1Department of Physiopathology, Faculty of Medicine, Université Libre de Bruxelles, Brussels, Belgium. ielham.hadad@ulb.ac.be
Insights
Stroma cell-derived factor-1α (SDF-1α) signaling enhances heart cell calcium release and beating frequency via CXCR4. This mechanism contributes to SDF-1α
Area of Science:
- Cardiology
- Molecular Biology
- Cell Physiology
Background:
- Stroma cell-derived factor-1α (SDF-1α) is a cardioprotective chemokine acting via CXCR4.
- SDF-1α improves systolic function post-myocardial infarction, but mechanisms beyond anti-apoptosis and angiogenesis are unclear.
Purpose of the Study:
- To investigate the direct effects of SDF-1α signaling on cardiomyocyte calcium transients and beating frequency.
- To elucidate the specific ion channels and signaling pathways involved in SDF-1α-mediated cardiac effects.
Main Methods:
- Primary rat neonatal cardiomyocytes were cultured and analyzed for protein expression (troponin I, CXCR4).
- Calcium sparks and transients were measured using fluorescence microscopy with Fluo-4 AM.
- Effects of SDF-1α, anti-CXCR4 antibodies, and IP3R/RyR blockers were assessed.
- Cardiomyocyte beating frequency and in vivo cardiac function (dP/dtmax) were evaluated.
Main Results:
- SDF-1α increased cytoplasmic calcium release in cardiomyocytes.
- This calcium response was dependent on CXCR4 and partially mediated by inositol triphosphate receptors (IP3R), not ryanodine receptors (RyR).
- SDF-1α and forskolin additively increased beating frequency, and SDF-1α improved in vivo cardiac function.
Conclusions:
- SDF-1α/CXCR4 signaling directly enhances cardiomyocyte calcium transients through an IP3-gated mechanism.
- This signaling pathway mediates positive chronotropic and inotropic effects, contributing to SDF-1α's cardioprotective role.
- Findings suggest novel therapeutic targets for myocardial infarction treatment.
Abstract:
Stroma cell-derived factor-1α (SDF-1α) is a cardioprotective chemokine, acting through its G-protein coupled receptor CXCR4. In experimental acute myocardial infarction, administration of SDF-1α induces an early improvement of systolic function which is difficult to explain solely by an anti-apoptotic and angiogenic effect. We wondered whether SDF-1α signaling might have direct effects on calcium transients and beating frequency.Primary rat neonatal cardiomyocytes were culture-expanded and characterized by immunofluorescence staining. Calcium sparks were studied by fluorescence microscopy after calcium loading with the Fluo-4 acetoxymethyl ester sensor. The cardiomyocyte enriched cellular suspension expressed troponin I and CXCR4 but was vimentin negative. Addition of SDF-1α in the medium increased cytoplasmic calcium release. The calcium response was completely abolished by using a neutralizing anti-CXCR4 antibody and partially suppressed and delayed by preincubation with an inositol triphosphate receptor (IP3R) blocker, but not with a ryanodine receptor (RyR) antagonist. Calcium fluxes induced by caffeine, a RyR agonist, were decreased by an IP3R blocker. Treatment with forskolin or SDF-1α increased cardiomyocyte beating frequency and their effects were additive. In vivo, treatment with SDF-1α increased left ventricular dP/dtmax.These results suggest that in rat neonatal cardiomyocytes, the SDF-1α/CXCR4 signaling increases calcium transients in an IP3-gated fashion leading to a positive chronotropic and inotropic effect.
