Figure 2.

Microinjection procedure for FRAP measurements in skeletal muscle fibers. To achieve locally a state of evenly distributed fluorophores, microinjections were performed at two sites along the longitudinal fiber axis (abscissa, peaks of curves refer to injection sites). In most of the experiments, the distance between the injection sites was around 400 μm. Measurements of the fluorescence intensity (ordinate) distribution were performed at different times after microinjection (after 3, 10, 15, 20, and 35 min in this example). The scans at 20 min and 35 min reveal a fiber segment 200 μm in length (horizontal bar) with almost constant fluorescence intensity.