Figure 4. Whole body protein turnover in postabsorptive juvenile and adult mdx and control mice.

Whole body rates of protein breakdown, synthesis, and protein balance were estimated from rates of phenylalanine appearance and its conversion to tyrosine. At both ages, rates of synthesis and breakdown were significantly higher in mdx than control mice. Net balance was significantly more negative in mdx mice and positively correlated to phenylalanine flux (r = 0.97). In both mdx and control mice there was a decrease with age in all parameters. Values are least square means (adjusted for FFM) ±SE; n = 5 and 6/group in juvenile and adult mice, respectively.