Figure 1.

Multifaceted signals underlying mitoflashes. (A–H) Mitoflashes in adult cardiomyocytes were measured by multiple reporters, including mt-cpYFP (A, F, and H), SNARF-1 (A), pHTomato (B), mitoSOX (C), DCF (D), grx1-roGFP2 (E), and TMRM (E and H), as well as autofluorescence of NADH (F) and FAD (G). Increases in SNARF-1 and pHTomato fluorescence indicate alkalinization of the mitochondrial matrix. MitoSOX was used for the detection of superoxide production, and DCF was used to report changes in the total ROS level. The DCF signal was processed by subtracting the baseline increase. An increase in grx1-roGFP2 fluorescence reflects the shift of the mitochondrial redox potential toward oxidation, and a decrease in the TMRM signal reflects mitochondrial depolarization. NADH autofluorescence (420–470 nm) was measured at 720 nm two-photon excitation. FAD autofluorescence was measured between 500 and 650 nm at 488 nm excitation. An increase of FAD autofluorescence indicates a decrease of FADH₂ content. All mitoflashes shown occurred spontaneously. To see this figure in color, go online.