Fig. 4.

Increased ribosome content during hypertrophy is blunted in aged animals. Total RNA content, of which >85% is ribosomal RNA, increased in response to synergist ablation (SA), indicating increased ribosome biogenesis. Conversely, skeletal muscle of old animals demonstrated a compromised ability to increase total RNA content in response to synergist ablation. Old animals demonstrated a delayed increase in RNA content, not occurring until at SA10 and SA14. Furthermore, at SA5 through SA14, RNA content was significantly lower in the old animals relative to the young animals. *Significant age-effect at that time-point; †significant increase from sham (P < 0.05).