Fig. 3

Twitch sarcomere length kinetics and Ca²⁺ transient signals of dystrophin-deficient flexor digitorum brevis (FDB) fibers from mdx mice treated with vehicle (1 mouse, 10 fibers) and P188 (3 mice each; 15 μM, 48 fibers; 150 μM, 33 fibers). A–C Representative ensemble average of sarcomere length shortening patterns from mdx FDB treated with vehicle and P188 (15 μM, 150 μM). Sarcomere length on the Y-axis is inverted. Each tick on the Y-axis is 0.05 μm. Electric field stimulation was applied at 0.2-s point. D Peak sarcomere length shortening during twitch contraction. E Time to peak sarcomere length shortening during twitch contraction. F Time from peak to 75% of baseline of sarcomere length during twitch contraction. G–I Ensemble average of Ca²⁺ transient patterns measured by Fura-2AM fluorescence from mdx FDB fibers treated with vehicle and P188 (15 μM, 150 μM). Each tick on the Y-axis is 0.1. J Peak Ca²⁺ transient during twitch contraction. K Time to peak Ca²⁺ transient during twitch contraction. L Time from peak to 75% of baseline of Ca²⁺ transient during twitch contraction. Dotted lines represent the average values from BL10 FDB (D–F, J–L). *P < 0.05, **P < 0.001 by one-way ANOVA with Holm-Sidak’s post hoc test