Assaying sarcoplasmic reticulum Ca2+-leak in mouse atrial myocytes
image: Separating Ca2+ signals from background noises in confocal line-scan images of atrial myocytes. A Typical normalized confocal line-scan Ca2+ images of atrial myocytes in the presence (upper) or absence (lower) of 10 μmol/L tetracaine, for which the histograms of pixel fluorescence were fitted into modified Gaussian curves in the right panel. The blue arrow indicates the difference between raw and fitting traces, which represents the signal components. B Statistics of Fsignals and Rsignals calculated from the histogram and corresponding fitting curves of line-scan Ca2+ images of atrial myocytes from the WT mice in the presence or absence of tetracaine, n = 10 atrial myocytes from three mice per group
Credit: Xu F, Li JJ, Yang E, Zhang Y, Xie WJ
Atrial fibrillation (AF) is a heart rhythm disorder with an irregular and rapid heartbeat. Research is focusing on the role of calcium leakage from the sarcoplasmic reticulum (SR) in causing AF. Accurate measurement of this leakage is essential for understanding its role in the condition and for developing new treatments. A recent study used a new imaging technique to measure total SR Ca2+ leakage in atrial myocytes (heart muscle cells).
The study’s method involved:
- Using a fluorescent calcium indicator and confocal microscopy to image atrial myocytes and capture high-speed line-scan images along their length.
- Analyzing the images to extract Ca2+ signal components by accounting for background noise with a modified Gaussian distribution.
- Calculating two new parameters, Fsignals and Rsignals, which represent total signal fluorescence and the fluorescence during the signal’s rising phase, respectively.
Key findings:
- Fsignals and Rsignals are strongly associated with traditional measures of SR Ca2+ leakage.
- These parameters can distinguish between normal and mutant atrial myocytes, suggesting increased Ca2+ leakage in the mutant group.
The work entitled “Assaying sarcoplasmic reticulum Ca2+-leak in mouse atrial myocytes” was published on Biophysics Reports (published on February, 2024).