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The effect of aging on rates of muscle protein synthesis in the basal state and in response to insulin and amino acid infusion in men and women
Author(s) -
Smith Gordon I,
Reeds Dominic N,
Mohammed B Selma,
Mittendorfer Bettina
Publication year - 2011
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.25.1_supplement.1064.1
Subject(s) - medicine , basal (medicine) , endocrinology , insulin , turnover , basal metabolic rate , protein turnover , ageing , skeletal muscle , biology , protein biosynthesis , biochemistry , management , economics
Although there appear to be no differences in muscle protein turnover in young/middle aged men and women, we have reported significant differences in the rate of muscle protein synthesis (MPS) in older adults. This suggests that aging may affect muscle protein turnover differently in men and women. To test this hypothesis we measured rates of MPS (by using stable isotope‐labeled tracer methods) during basal postabsorptive conditions and during i.v. insulin/amino acid (AA) infusion in 25–45 y old men and women (n=8 each) and 65–80 y old men and women (n=8 each). The basal rate of MPS was not different in young and old men (0.040 ± 0.004 vs. 0.038 ± 0.004 %/h, respectively; P=0.75) with an increase in the rate of MPS during insulin and AA infusion only observed in young but not old men (to 0.063 ± 0.006 and 0.044 ± 0.007 %/h, respectively; P<0.01). In contrast, the basal rate of MPS was faster in old than young women (0.060 ± 0.004 vs. 0.043 ± 0.004 %/h, respectively; P<0.01) and the rate of MPS during insulin/AA infusion was not different in young and old women (0.075 ± 0.007 vs. 0.076 ± 0.006 %/h, respectively; P=0.70). We conclude that there is sexual dimorphism in the age‐associated changes in MPS and thus the metabolic processes responsible for the age‐related decline in muscle mass.