Superoxide flashes in mouse skeletal muscle are produced by discrete arrays of active mitochondria operating coherently.

Pouvreau S(1).

Author information:
(1)Physiologie Intégrative, Cellulaire et Moléculaire, Université Lyon 1, UMR
CNRS 5123, Villeurbanne, France.

Reactive Oxygen Species (ROS) constitute important intracellular signaling
molecules. Mitochondria are admitted sources of ROS, especially of superoxide
anions through the electron transport chain. Here the mitochondria-targeted
ratiometric pericam (RPmt) was used as a superoxide biosensor, by appropriate
choice of the excitation wavelength. RPmt was transfected in vivo into mouse
muscles. Confocal imaging of isolated muscle fibers reveals spontaneous flashes
of RPmt fluorescence. Flashes correspond to increases in superoxide production,
as shown by simultaneous recordings of the fluorescence from MitoSox, a
mitochondrial superoxide probe. Flashes occur in all subcellular populations of
mitochondria. Spatial analysis of the flashes pattern over time revealed that
arrays of mitochondria work as well-defined superoxide-production-units.
Increase of superoxide production at the muscle fiber level involves recruitment
of supplemental units with no increase in per-unit production. Altogether, these
results demonstrate that superoxide flashes in muscle fibers correspond to
physiological signals linked to mitochondrial metabolism. They also suggest that
superoxide, or one of its derivatives, modulates its own production at the
mitochondrial level.

DOI: 10.1371/journal.pone.0013035
PMCID: PMC2946926
PMID: 20927399 [Indexed for MEDLINE]

Conflict of interest statement: Competing Interests: The author has declared
that no competing interests exist.

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