Figure 4.

Confocal laser-scanning micrographs showing the autofluorescence of flavoproteins (a, b, a′, b′) and the fluorescence signal of the mitochondrial marker DASPMI (c, d, c′, d′) within three different saponin-permeabilized mouse quadriceps muscle fibers. One single confocal plane across these fibers is illustrated in (a–d); one cross-section, reconstructed from a stack of 130 different confocal planes (z-stack), is shown in (a′–d′). The arrowheads in a indicate the site of the reconstructed cross-section. a and a′, oxidized state; b and b′, addition of 10 mM glutamate and 5 mM malate; c and c′, addition of 5 μM DASPMI; d and d′, addition of 5 μM TTFB. To visualize the DASPMI signal (c and c′, d and d′) the laser excitation energy was reduced to 30%. Bar, 50 μm.