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Measuring Fast Calcium Fluxes in Cardiomyocytes
Published on: November 29, 2011
Quarky calcium release in the heart
Didier X P Brochet1, Wenjun Xie, Dongmei Yang
1Center for Biomedical Engineering and Technology, University of Maryland, Baltimore, MD, USA. dbrochet@umaryland.edu
Circulation Research
|December 15, 2010
Summary
New "quarky" Ca(2+) release (QCR) events, smaller than sparks, were discovered in heart cells. These QCR events contribute significantly to calcium leak and spark characteristics.
Area of Science:
- Cardiology
- Cellular Physiology
- Molecular Biology
Background:
- Cardiac myocytes utilize calcium (Ca2+) sparks for Ca2+ release via ryanodine receptors (RyRs).
- Ca2+ blinks represent Ca2+ depletion signals in the sarcoplasmic reticulum.
- Substructures within local Ca2+ release events are increasingly recognized.
Purpose of the Study:
- To investigate Ca2+ release events smaller than sparks.
- To analyze the interplay between these small events and regular Ca2+ sparks.
- To enhance detection sensitivity using simultaneous spark-blink pair measurements.
Main Methods:
- Direct visualization of spontaneous Ca2+ quark-like or "quarky" Ca2+ release (QCR) events in rabbit ventricular myocytes.
- Simultaneous spark-blink pair measurements.
- Experimental evidence combined with computational modeling.
Main Results:
- Discovery of QCR events, smaller than sparks, in cardiac myocytes.
- QCR events contribute significantly to total Ca2+ leak, comparable to Ca2+ sparks.
- Spark Ca2+ release comprises a stereotypical component and a variable QCR component.
- QCR component is sensitive to Ca2+ buffering, suggesting a Ca2+-induced Ca2+ release mechanism.
- QCR events may originate from rogue or small clusters of RyR2s.
Conclusions:
- QCR events are crucial in defining elemental Ca2+ release.
- Non-spark QCR events represent a significant source of "invisible" Ca2+ leak.
- These findings have implications for understanding Ca2+ handling in cardiac health and disease.
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