FIG. 2.

Endogenous GM130 is localized in vesicle-like structures in resting muscle fibers and is not reduced by muscle contractions. A: Image of GM130 immunostaining; shown are GM130-positive structures (arrows) in resting TA muscle fiber. Bar = 20 μm. B: Image of GM130 immunostaining in TA muscle fibers subjected to 45 min of in situ muscle contractions. Similar observations were made in fibers from 6 mice. Inserts are magnified parts of the images. Bars = 20 μm. C–E: Quantification of immunostained GM130 vesicle number (C), average vesicle light intensity (D), and average vesicle size (E) from basal and contraction-stimulated muscle fibers. No significant reduction in number, intensity, or area of GM130-positive vesicles was detected after 45 min of in situ contractions. Values are mean ± SE, n = 6.