Fig. 2.

β-Arrestin-biased agonist carvedilol enhanced contractility of skeletal muscle. Force–frequency curves for EDL muscles from βarr1Flox mice after 2 wk of clenbuterol (1 mg/kg/day) (A and F), carvedilol (1 mg/kg/day) (B and G), metoprolol (10 mg/kg/day) (C and H), nadolol (10 mg/kg/day) (D and I), nadolol (10 mg/kg/day) combined with carvedilol (1 mg/kg/day) (E and J) compared to vehicle (10% DMSO, 300 mM ascorbic acid in saline solution) treatment. The contractile amplitudes at each frequency and for each treatment group normalized by EDL wet weight were presented (A–E). The contractile amplitudes normalized by EDL dry weight were presented (F–J). Data represent the mean ± SEM for n independent EDL muscles as marked in the figure. Vehicle-treated group was used to compare to all treatments. Statistical significance versus vehicle-treated group was performed by using a two-way ANOVA with Sidak’s multiple comparison test (*P < 0.05; **P < 0.01; ***P < 0.001).