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The basal rate of muscle protein synthesis and its response to hyperinsulinemia‐hyperaminoacidemia are the same in young men and women
Author(s) -
Smith Gordon I,
Reeds Dominic N,
Mohammed B Selma,
Jaffery Hadia,
Mittendorfer Bettina
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.23.1_supplement.991.23
Subject(s) - anabolism , endocrinology , medicine , basal (medicine) , hyperinsulinemia , protein turnover , sexual dimorphism , turnover , biology , insulin , insulin resistance , protein biosynthesis , biochemistry , management , economics
We have recently shown that there are considerable sex differences in muscle protein turnover in 65‐80 year old adults. Specifically we found that the basal rate of muscle protein synthesis (MPS) is greater in elderly women than elderly men whereas the anabolic response of MPS to feeding is greater in elderly men than elderly women (PLoS One 3:1875‐83, 2008). The purpose of this study was to determine whether similar differences in muscle protein metabolism exist in younger individuals. We therefore measured the rate of MPS during basal, postabsorptive conditions and during combined hyperinsulinemia and hyperaminoacidemia by using stable isotope‐labeled tracer techniques in 7 men and 5 women, who were matched on age (mean ± SEM: 40 ± 2 y vs 38 ± 3 y, respectively; P = 0.63) and body‐mass index (26.2 ± 1.1 kg.m 2 vs 25.8 ± 1.3 kg.m 2 , respectively; P = 0.84). The basal rate of MPS was not different in men (0.041 ± 0.006 % ·h −1 ) and women (0.040 ± 0.006 % ·h −1 ). Hyperinsulinemia‐hyperaminoacidemia resulted in a significant increase in the rate of MPS (P < 0.001) in both men (to 0.062 ± 0.007 % ·h −1 ) and women (to 0.064 ± 0.010 %·h −1 ) with no difference (P = 0.71) in the magnitude of the anabolic response. Thus, sexual dimorphism in muscle protein turnover is a phenomenon associated with old age. The underlying mechanism(s) remain to be elucidated but are probably due to sex specific hormonal changes that accompany the aging process in men and women. This research was supported by grants from the US NIH.