Rate of protein synthesis in skeletal muscle of normal man and patients with muscular dystrophy: A reassessment

Abstract

1. Quadriceps muscle protein synthetic rate has been determined in healthy subjects in the post-absorptive (n = 18) and fed (n = 10) states and in patients with a variety of myopathies, by analysis of the enrichment of serial muscle biopsies taken during primed continuous infusion of L-[1-13C]leucine. 2. Quadriceps protein synthetic rates in normal subjects were (mean .+-. SD) 0.046 .+-. 0.012 and 0.075 .+-. 0.014%/h in the post-absorptive and fed states respectively. These results are significantly lower than we previously reported (M.J. Rennie et al., Clinical Science, 1982, 63, 519-523 [1]) but show the same relative differences of direction and magnitude, confirming the effects of feeding previously reported. In patients with muscular dystrophy, muscle protein synthetic rate was, as previously reported [1], much lower in the fed state than in normal subjects. A new finding is that for patients with myotonic dystrophy the rate is also depressed in the postabsorptive state. 3. We suggest that the present estimates in postabsorptive and fed normal subjects be used as reference values for quadriceps mixed muscle protein synthetic rate.