Figure 1.

Experimental setup and radial diffusion of endogenous cytosolic proteins into relaxing solution from skinned fiber segments of rabbit psoas muscle. (A) The experimental protocol, where each fiber is placed sequentially in either two or three drops of relaxing solution (∼10 μL each) for a specified period of time ranging from 2 s to 20 min (see text). (B) Proteins separated by SDS polyacrylamide gel electrophoresis with silver-stained gel. Proteins are identified as in Maughan et al. (3). Lanes 2–4, cytosolic protein fractions obtained by sequentially incubating the skinned fiber for 35 s (lane 2, load 5.4 μL = 51% of total volume), 80 s (lane 3, load 7.2 μL = 68% of total), and 1440 s (lane 4, load 10 μL = 90% of total) in 10 μL relaxing solution drops. Lane 1, cytomatrix fraction (residual fiber, load 5 μL = 14% of total). Fiber radius, 29.5 μm; fiber length, 6.56 mm.