Fig. 4.

Clustered “yielding” in untreated and antibody-treated myofibrils. The spatial distribution of ΔSL along a myofibril (A), the spatial pattern of “resisting” and “yielding” sarcomeres at each stretch (B), and the distribution of ΔSL pooled over 5 stretches (C), under stretch repeated 5 times are shown. ΔP was chosen to be around ΔP₅₀ for each condition; 0.075 P₀ in untreated myofibrils (left panels) and 0.15 P₀ in antibody-treated myofibrils (right panels). The loading rate was 0.02 P₀/ms. The sarcomere responses classified as either “resisting” or “yielding” are colored in gray or orange, respectively, in B and C. The stiff needle was at the left side of the sarcomere number 1. (D) The spatial correlation of ΔSL between sarcomeres is plotted for untreated (open circles, n = 4 myofibrils) or treated (filled circles, n = 6 myofibrils) preparations. The plots were mean ± SD obtained from a total of 20 and 30 stretches, respectively (5 times in each myofibril). For details, see Materials and Methods.