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Analyses of Mitochondrial Calcium Influx in Isolated Mitochondria and Cultured Cells
Published on: April 27, 2018
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Calcium movement in cardiac mitochondria.
Liron Boyman1, Aristide C Chikando1, George S B Williams2
1Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, Maryland; Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland.
Biophysical Journal
|September 18, 2014
Summary
Mitochondria do not significantly buffer cytosolic calcium in heart cells during contractions. Experiments show that altering mitochondrial function does not change calcium signals, challenging existing theories.
Area of Science:
- Cardiology
- Cell Biology
- Mitochondrial Physiology
Background:
- Mitochondria are theorized to be significant buffers of cytosolic calcium ([Ca(2+)]i) in cardiomyocytes.
- They may buffer up to one-third of calcium entering the cytosol during contractions.
Purpose of the Study:
- To quantitatively investigate the role of mitochondria in buffering cytosolic calcium signals in rat cardiomyocytes.
- To assess the influence of mitochondrial calcium uptake on subcellular and global cytosolic calcium dynamics.
Main Methods:
- Rapidly depolarized the inner mitochondrial membrane potential (ΔΨm) to inhibit mitochondrial calcium uptake.
- Measured mitochondrial calcium ([Ca(2+)]m) using a targeted probe (MityCam).
- Employed computational modeling of mitochondrial calcium cycling.
Main Results:
- Inhibition of mitochondrial function did not significantly alter cytosolic calcium signals (sparks and transients).
- Mitochondrial calcium levels were found to be near cytosolic levels under quiescent conditions.
- Computational models indicated mitochondrial calcium uptake needs to be ~100-fold higher to impact cytosolic calcium.
Conclusions:
- Mitochondria do not act as significant dynamic buffers of cytosolic calcium ([Ca(2+)]i) under physiological conditions in the heart.
- Despite buffer capacity, mitochondria do not measurably influence cytosolic calcium signaling during normal heart cell activity.
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