TY - JOUR
T1 - Sexually dimorphic effect of aging on skeletal muscle protein synthesis
AU - Smith, Gordon I.
AU - Reeds, Dominic N.
AU - Hall, Angela M.
AU - Chambers, Kari T.
AU - Finck, Brian N.
AU - Mittendorfer, Bettina
N1 - Funding Information:
This publication was supported by NIH grants AR 49869, HD57796, DK87821, UL1 RR024992 (Washington University Clinical Translational Science Award), RR 00954 (Biomedical Mass Spectrometry Resource), and DK 56341 (Nutrition and Obesity Research Center), and a grant from the Longer Life Foundation. Kari Chambers was supported by an American Liver Foundation Liver Scholar Award and Dominic Reeds was supported by an American Society of Nutrition Physician Nutrition Support Specialist Award.
PY - 2012
Y1 - 2012
N2 - Background: Although there appear to be no differences in muscle protein turnover in young and middle aged men and women, we have reported significant differences in the rate of muscle protein synthesis between older adult men and women. This suggests that aging may affect muscle protein turnover differently in men and women. Methods: We measured the skeletal muscle protein fractional synthesis rate (FSR) by using stable isotope-labeled tracer methods during basal postabsorptive conditions and during a hyperaminoacidemic-hyperinsulinemic- euglycemic clamp in eight young men (25-45 y), ten young women (25-45 y), ten old men (65-85 y) and ten old women (65-85 y). Results: The basal muscle protein FSR was not different in young and old men (0.040±0.004 and 0.043±0.005%·h-1, respectively) and combined insulin, glucose and amino acid infusion significantly increased the muscle protein FSR both in young (to 0.063±0.006%·h-1) and old (to 0.051±0.008%·h-1) men but the increase (0.023±0.004 vs. 0.009±0.004%·h-1, respectively) was ~60% less in the old men (P= 0.03). In contrast, the basal muscle protein FSR was ~30% greater in old than young women (0.060±0.003 vs. 0.046±0.004%·h-1, respectively; P<0.05) and combined insulin, glucose and amino acid infusion significantly increased the muscle protein FSR in young (P<0.01) but not in old women (P=0.10) so that the FSR was not different between young and old women during the clamp (0.074±0.006%·h-1 vs. 0.072±0.006%·h -1, respectively). Conclusions: There is sexual dimorphism in the age-related changes in muscle protein synthesis and thus the metabolic processes responsible for the age-related decline in muscle mass.
AB - Background: Although there appear to be no differences in muscle protein turnover in young and middle aged men and women, we have reported significant differences in the rate of muscle protein synthesis between older adult men and women. This suggests that aging may affect muscle protein turnover differently in men and women. Methods: We measured the skeletal muscle protein fractional synthesis rate (FSR) by using stable isotope-labeled tracer methods during basal postabsorptive conditions and during a hyperaminoacidemic-hyperinsulinemic- euglycemic clamp in eight young men (25-45 y), ten young women (25-45 y), ten old men (65-85 y) and ten old women (65-85 y). Results: The basal muscle protein FSR was not different in young and old men (0.040±0.004 and 0.043±0.005%·h-1, respectively) and combined insulin, glucose and amino acid infusion significantly increased the muscle protein FSR both in young (to 0.063±0.006%·h-1) and old (to 0.051±0.008%·h-1) men but the increase (0.023±0.004 vs. 0.009±0.004%·h-1, respectively) was ~60% less in the old men (P= 0.03). In contrast, the basal muscle protein FSR was ~30% greater in old than young women (0.060±0.003 vs. 0.046±0.004%·h-1, respectively; P<0.05) and combined insulin, glucose and amino acid infusion significantly increased the muscle protein FSR in young (P<0.01) but not in old women (P=0.10) so that the FSR was not different between young and old women during the clamp (0.074±0.006%·h-1 vs. 0.072±0.006%·h -1, respectively). Conclusions: There is sexual dimorphism in the age-related changes in muscle protein synthesis and thus the metabolic processes responsible for the age-related decline in muscle mass.
KW - Aging
KW - Amino acid
KW - Muscle protein turnover
KW - Sarcopenia
UR - http://www.scopus.com/inward/record.url?scp=84878667473&partnerID=8YFLogxK
U2 - 10.1186/2042-6410-3-11
DO - 10.1186/2042-6410-3-11
M3 - Article
C2 - 22620287
AN - SCOPUS:84878667473
SN - 2042-6410
VL - 3
JO - Biology of Sex Differences
JF - Biology of Sex Differences
IS - 1
M1 - 11
ER -