Fig. 1

β-arrestin 1 is required for clenbuterol-mediated enhanced contractility of skeletal muscle. a Tissue lysates from muscle, heart, spleen of WT and βarr1KO mice subjected to measure β-arrestin 1 expression by immunoblotting using anti-β-arrestin 1 antibody (A1ct). Equal amounts of tissue lysates loaded were probed by immunoblotting using anti-GAPDH antibody. b, c Force-frequency curves for EDL muscles after 2 weeks of vehicle or clenbuterol (1 mg/kg/day) treatment from WT (b) and βarr1KO (c). Data represent the mean ± SEM from six to eight independent experiments. Statistical comparison of the curves was performed by using a two-way ANOVA with Tukey’s multiple comparison test (*, P < 0.05; **, P < 0.01; ***, P < 0.001)