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Updated: Apr 20, 2026
Multi-parameter Measurement of the Permeability Transition Pore Opening in Isolated Mouse Heart Mitochondria
Published on: September 7, 2012
Photo-induction and automated quantification of reversible mitochondrial permeability transition pore opening in
Lionel Blanchet1, Sander Grefte2, Jan A M Smeitink3
1Department of Biochemistry, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands; Institute for Molecules and Materials, Analytical Chemistry/Chemometrics, Radboud University Nijmegen, Nijmegen, The Netherlands; Centre for Systems Biology and Bioenergetics, Radboud University Medical Center, Nijmegen, The Netherlands.
Abstract:
Opening of the mitochondrial permeability transition pore (mPTP) is involved in various cellular processes including apoptosis induction. Two distinct states of mPTP opening have been identified allowing the transfer of molecules with a molecular weight <1500 Da or <300 Da. The latter state is considered to be reversible and suggested to play a role in normal cell physiology. Here we present a strategy combining live-cell imaging and computer-assisted image processing allowing spatial visualization and quantitative analysis of reversible mPTP openings ("ΔΨ flickering") in primary mouse myotubes. The latter were stained with the photosensitive cation TMRM, which partitions between the cytosol and mitochondrial matrix as a function of mitochondrial membrane potential (ΔΨ). Controlled illumination of TMRM-stained primary mouse myotubes induced ΔΨ flickering in particular parts of the cell ("flickering domains"). A novel quantitative automated analysis was developed and validated to detect and quantify the frequency, size, and location of individual ΔΨ flickering events in myotubes.
Insights
Researchers visualized reversible mitochondrial permeability transition pore (mPTP) openings, termed "ΔΨ flickering," in mouse myotubes using live-cell imaging. This study quantifies these flickering events, offering insights into normal cell physiology.
Area of Science:
- Cell Biology
- Mitochondrial Physiology
- Biophysics
Background:
- Mitochondrial permeability transition pore (mPTP) opening is implicated in apoptosis.
- Two mPTP opening states exist: one for molecules <1500 Da and a reversible state for molecules <300 Da, potentially vital for cell function.
Purpose of the Study:
- To develop and validate a method for spatial visualization and quantitative analysis of reversible mPTP openings in primary mouse myotubes.
- To investigate the phenomenon of "ΔΨ flickering" in cellular physiology.
Main Methods:
- Live-cell imaging of primary mouse myotubes stained with tetramethylrhodamine methyl ester (TMRM).
- Controlled illumination to induce mitochondrial membrane potential (ΔΨ) fluctuations.
- Development and application of automated computer-assisted image processing for quantitative analysis of ΔΨ flickering events.
Main Results:
- Controlled illumination induced localized, reversible mPTP openings ("ΔΨ flickering") in TMRM-stained myotubes.
- A novel automated analysis successfully detected and quantified the frequency, size, and location of individual ΔΨ flickering events.
- The study demonstrated the feasibility of analyzing dynamic mPTP behavior in living cells.
Conclusions:
- Reversible mPTP openings ("ΔΨ flickering") can be spatially visualized and quantitatively analyzed in primary mouse myotubes.
- The developed methodology provides a powerful tool for studying the physiological roles of dynamic mPTP activity.
- This research offers new insights into the functional significance of transient mPTP states in cell biology.
