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Ca2+ blinks: rapid nanoscopic store calcium signaling.
Didier X P Brochet1, Dongmei Yang, Alessandro Di Maio
1Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA.
Summary
Rapid "Ca(2+) blinks" in heart cell stores reveal localized calcium signaling dynamics. These localized events, distinct from broader calcium sparks, offer new insights into cardiac calcium regulation.
Area of Science:
- Cardiovascular Physiology
- Cellular Biology
- Calcium Signaling
Background:
- Luminal Ca(2+) in endoplasmic and sarcoplasmic reticulum (ER/SR) is crucial for cellular processes.
- Dysregulation of ER/SR Ca(2+) contributes to various pathologies.
Purpose of the Study:
- To investigate the dynamics of luminal Ca(2+) within nanometer-sized SR stores during Ca(2+) release events.
- To understand the mechanisms underlying Ca(2+) spark termination and refractoriness.
Main Methods:
- Utilized advanced imaging techniques to visualize rapid changes in luminal Ca(2+) within localized SR regions.
- Correlated changes in luminal Ca(2+) with cytoplasmic Ca(2+) sparks in heart cells.
Main Results:
- Observed rapid, localized decreases in luminal Ca(2+) ("Ca(2+) blinks") within SR junctional cisternae during Ca(2+) sparks.
- Found that luminal Ca(2+) depletion lagged behind cytoplasmic Ca(2+) spark peaks.
- Demonstrated faster refilling rates of local SR stores compared to the recovery of Ca(2+) release.
Conclusions:
- Localized Ca(2+) blinks provide a novel view of Ca(2+) signaling within cardiac SR.
- Both local store depletion and inhibitory mechanisms contribute to spark termination.
- Findings suggest potential for localized regulation of diverse ER/SR Ca(2+)-dependent functions.