Figure 5. RLC orientation change during active isometric contraction.

(a) Steady force at different pCa normalized by the maximum force at pCa 4.7 (267±10 kPa; mean±s.e., n=5 fibres) in the presence (triangles; mean±s.e., n=5 fibres; error bars are smaller than symbol size) and absence (circles; mean±s.e., n=5 fibres) of 25 μM Blebbistatin. Sarcomere length 2.40 μm, 25 °C, 5% Dextran. (b) <P₂> for the E-helix probe in the same experiments. (c) Force-dependence of Δ<P₂> during active contraction (filled circles, from a,b) compared with that for the end of phase 2 after force steps in the presence of 25 μM Blebbistatin (data from Fig. 4b).