Fig. 4.

ECG recordings in young mdx mice. ECGs were recorded as described in SI Materials and Methods. (A) Typical ECGs acquired by telemetry in 35-day-old vigil mice over 24 h and analyzed specifically during the 12-h overnight period in WT (Top; n = 5), mdx (Middle; n = 5), and S107-mdx treated (Bottom; n = 5) mice in normal condition (Left) and after i.p. injection of isoproterenol (2.5 mg · kg^-1) (Right). (B–F) ECG analysis provides various functional parameters, including cardiac frequency given by the RR interval (B), heart rate variability expressed as SDNN (C), PVCs (D), QRS duration (E), and QT interval (F). (G) The QT interval also was measured after isoproterenol challenge. (H) Typical spontaneous sustained VT recorded in mdx mice after isoproterenol challenge. Note that VT was never triggered by isoproterenol treatment in either WT or S107-treated mice. *P < 0.05 control vs. mdx; #P < 0.05 mdx vs. S107-treated mdx.