Elevation of Orai1-mediated SOCE activity and SR Ca²⁺ store overload in adult mdx muscles.

(A) Representative trace of Mn²⁺ quenching of Fura-2 fluorescence at 360 nm (F₃₆₀) wavelength. Lines and arrows designate perfusion of muscle fiber by 20 mM caffeine plus 5 uM ryanodine, MnCl₂ and TritonX-100. Upper panel: black trace is FDB fiber from wt mice transfected with empty vector (control WT) and grey trace is with shOrai1 (Orai1KD WT); lower panel: black trace is FDB fiber from mdx mice transfected with empty vector (Control mdx) and grey trace is with Orai1 (Orai1KD mdx). (B) Statistical summarization of the data in (A), n = 11–19, ^*P<0.05 compared to Control WT; ^#P<0.05 compared to Control mdx. (C) Statistical results of resting intracellular Ca²⁺ levels in Control WT (open bar), Orai1KD WT (black bar), Control mdx (hatched bar) and Orai1KD mdx (black bar). (D) Statistical results of caffeine-sensitive SR Ca²⁺ store in the four groups. n = 11–19, ^*P<0.05 compared to Control WT; ^#P<0.05 compared to Control mdx.