Title
Quantitative analysis of spontaneous mitochondrial depolarizations
UMMS Affiliation
Department of Physiology and Biomedical Imaging Group
Publication Date
10-29-2003
Document Type
Article
Subjects
Animals; Bufo marinus; Cells, Cultured; Image Interpretation, Computer-Assisted; Imaging, Three-Dimensional; Membrane Potentials; Microscopy, Fluorescence; Mitochondria; Myocytes, Smooth Muscle; *Organometallic Compounds
Disciplines
Life Sciences | Medicine and Health Sciences
Abstract
Spontaneous transient depolarizations in mitochondrial membrane potential (DeltaPsi(m)), mitochondrial flickers, have been observed in isolated mitochondria and intact cells using the fluorescent probe, tetramethylrhodamine ethyl ester (TMRE). In theory, the ratio of [TMRE] in cytosol and mitochondrion allows DeltaPsi(m) to be calculated with the Nernst equation, but this has proven difficult in practice due to fluorescence quenching and binding of dye to mitochondrial membranes. We developed a new method to determine the amplitude of flickers in terms of millivolts of depolarization. TMRE fluorescence was monitored using high-speed, high-sensitivity three-dimensional imaging to track individual mitochondria in freshly dissociated smooth muscle cells. Resting mitochondrial fluorescence, an exponential function of resting DeltaPsi(m), varied among mitochondria and was approximately normally distributed. Spontaneous changes in mitochondrial fluorescence, indicating depolarizations and repolarizations in DeltaPsi(m), were observed. The depolarizations were reversible and did not result in permanent depolarization of the mitochondria. The magnitude of the flickers ranged from <10 mV to>100 mV with a mean of 17.6 +/- 1.0 mV (n = 360) and a distribution skewed to smaller values. Nearly all mitochondria flickered, and they did so independently of one another, indicating that mitochondria function as independent units in the myocytes employed here.
DOI of Published Version
10.1016/S0006-3495(03)74754-7
Source
Biophys J. 2003 Nov;85(5):3350-7.
Journal/Book/Conference Title
Biophysical journal
Related Resources
PubMed ID
14581236
Repository Citation
O'Reilly, Catherine M.; Fogarty, Kevin E.; Drummond, Robert M.; Tuft, Richard A.; and Walsh, John V., "Quantitative analysis of spontaneous mitochondrial depolarizations" (2003). Open Access Articles. 266.
https://escholarship.umassmed.edu/oapubs/266