Fig. 2

The distributions of β-ADR and β2-ADR were decreased in aged SCs. A, B WB analysis showed low expression of β1-ADR, high expression of β2-ADR, and almost no expression of β3-ADR (n = 5) (F = 18.95, P < 0.001). C, D The β2-ADR expression in the SCs of aged mice was significantly lower than that in the SCs of young mice (n = 5) (t = 6.321, P < 0.001). E, F Immunofluorescence staining showed that the expression of β2-ADR in the TA muscles of aged mice was lower than that in the TA muscles of young mice (n = 8) (t = 1.31, P = 0.014). G–J Immunofluorescence staining showed that the expression of PAX7 was not significantly decreased in the SCs of aged mice in vitro (n = 8) (t = 0.18, P = 0.25) but that the number of PAX7⁻ SCs (white arrow) in the proliferative phase was decreased significantly (n = 8) (t = 2.08, P = 0.007). The expression of β2-ADR was lower in aged mice than that in young mice (n = 8) (t = 1.67, P = 0.011). K The tissue concentration of NE was higher in young mice than in aged mice in both the noninjury and injury states (t = 3.07 and 2.97, P = 0.009 and 0.012). Independent samples t tests and one-way ANOVA with Tukey’s test, ns, not significant, *P < 0.05; **P < 0.001