Fig. 8. Ca²⁺ influx through SACs is mediated by ROS in mdx fibres and Src inhibition reduces stretch-induced muscle damage in mdx mice. (A) Single fibres from mdx mice were loaded with the fluorescent Ca²⁺ indicator Fluo-4 to measure changes in [Ca²⁺]_i. Fibres were then subjected to a series of ten stretched (eccentric) contractions without (control) or with the ROS scavenger Tiron (5 mM). (B) Changes in [Ca²⁺]_i in single muscle fibres from mdx and WT mice were measured. Following the addition of 10 µM H₂O₂ for 30 minutes, fibres were co-incubated with H₂O₂ and the SAC blocker streptomycin (200 µM) for 40 minutes, and then both drugs were washed out. (C) EDL muscle was dissected from mdx mice and a series of ten stretched contractions was performed. Recovery of the muscle force was measured at three time points after stretched contractions (0, 30 and 60 minutes). Compared with control muscles incubated with PP3, inhibition of Src kinase by PP2 protected mdx muscle from damage induced by stretched contractions. (A) n=9 for control and n=6 for Tiron; (B) n=4 for WT and n=6 for mdx; (C) n=3 per group. ^*P<0.05; ^**P<0.01; ^***P<0.001.