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Table 1 Effect of clenbuterol on skeletal muscle fiber composition of EDL

From: β-arrestin 1 regulates β2-adrenergic receptor-mediated skeletal muscle hypertrophy and contractility

  WT βarr1KO P value
Vehicle Clenbuterol Vehicle Clenbuterol Drug Strain
EDL
 I (%) 0.0 ± 0.0 0.1 ± 0.1 0.3 ± 0.2 0.9 ± 0.5   
 IIa (%) 12.7 ± 1.6 11.4 ± 1.4 13.7 ± 1.3 9.6 ± 1.7 *   
 IIb (%) 59.2 ± 3.7 68.4 ± 3.3 * 65.2 ± 2.3 73.7 ± 2.8 ** *  
 IIx (%) 28.1 ± 4.9 20.1 ± 2.1 ** 20.8 ± 1.9 15.8 ± 2.2 * *  
 I + IIa (%) 12.7 ± 1.6 11.5 ± 1.2 14.0 ± 1.4 10.5 ± 1.3 *   
 IIb + IIx (%) 87.3 ± 1.6 88.5 ± 1.2 86.0 ± 1.4 89.5 ± 1.3 *   
 N 7 8 7 8   
Soleus
 I (%) 48.8 ± 1.4 44.2 ± 1.8 48.9 ± 3.6 51.0 ± 2.0   
 IIa (%) 44.6 ± 1.6 44.5 ± 1.4 42.8 ± 3.3 36.6 ± 1.7   *
 IIb (%) 0.0 ± 0.0 2.5 ± 0.8 * 1.3 ± 0.8 5.0 ± 1.2 * ** *
 IIx (%) 6.7 ± 1.1 8.8 ± 0.9 7.0 ± 1.2 7.4 ± 1.2   
 I + IIa (%) 93.3 ± 1.1 88.8 ± 1.1 * 91.8 ± 1.3 87.6 ± 1.1 * **  
 IIb + IIx (%) 6.7 ± 1.1 11.3 ± 1.1 * 8.2 ± 1.3 12.4 ± 1.1* **  
 N 6 8 7 8   
Plantaris
 I (%) 0.0 ± 0.0 0.5 ± 1.2 2.9 ± 0.6 1.2 ± 0.3   *
 IIa (%) 33.3 ± 2.2 25.8 ± 2.0 * 23.7 ± 3.3 20.2 ± 0.8 * **
 IIb (%) 48.2 ± 3.7 58.3 ± 3.2 * 52.2 ± 4.7 68.5 ± 1.3 ** *** *
 IIx (%) 18.6 ± 2.3 15.1 ± 2.6 21.2 ± 1.5 10.2 ± 1.0 ** **  
 I + IIa (%) 33.3 ± 2.4 26.2 ± 2.0 * 26.6 ± 3.5 21.4 ± 0.8 * *
 IIb + IIx (%) 66.7 ± 2.4 73.8 ± 2.0 * 73.4 ± 3.5 78.6 ± 0.8 * *
 N 7 8 7 8   
  1. Values are means ± SEM. N, the number of muscles utilized for the analysis. P value next to the numbers compared to vehicle treatment. P values for drug and strain were calculated by a two-way ANOVA with Tukey’s multiple comparison test. *P < 0.05, **P < 0.01, ***P < 0.001