Intensity and spacing of the T1 reflection. (A and B) Intensity (A) and spacing (B) are shown. Mean ± SE. Open circles, no Dextran, n = 10 demembranated psoas fiber bundles; filled circles, 5% Dextran, n = 5; triangles, resting intact mouse EDL muscles, n = 3. Intensities are normalized by the value at 30°C in the absence of Dextran.