Fig. 4.

BaCl₂ disrupts myofiber plasma membranes. a, b Representative images of nuclear staining in EDL muscles after 1 h in standard PSS (control) and in 1.2% BaCl₂ added to standard PSS. Propidium iodide (PI, red) identifies nuclei of cells with disrupted plasma membranes and Hoechst 33342 (blue) is membrane permeant and identifies all cell nuclei. Removal of extracellular Ca²⁺ (0 [Ca²⁺]_o)ameliorated myonuclear staining with PI as in a. c Summary data for percentage of PI-labeled nuclei, calculated as (# red nuclei/# blue nuclei) × 100. Each region of interest contained ~ 150 myonuclei. Summary data are means ± SEM for n = 4–5 muscles per group. ^#P ≤ 0.05 vs. control, *P ≤ 0.05 vs. 1.2% BaCl₂ in standard PSS with 2 mM [Ca²⁺]_o. Scale bars, 100 μm