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Effect of type 2 diabetes (T2DM) on muscle protein metabolism in older subjects
Author(s) -
Fujita Satoshi,
Rasmussen Blake B,
Cadenas Jerson G,
Bell Jill A,
Volpi Elena
Publication year - 2006
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.20.4.a556
Subject(s) - medicine , endocrinology , insulin resistance , basal (medicine) , anabolism , phenylalanine , hyperinsulinemia , insulin , skeletal muscle , protein catabolism , metabolism , type 2 diabetes , glucose uptake , diabetes mellitus , biology , amino acid , biochemistry
Skeletal muscle protein synthesis and deposition are resistant to the anabolic effect of insulin in healthy, non‐diabetic, older subjects. We have also shown that muscle protein turnover is elevated in young, poorly controlled T2DM patients. We determined if T2DM worsens the insulin resistance of muscle proteins in older subjects. Using 13 C 6 ‐phenylalanine, we measured leg muscle protein kinetics (nmol/min/100ml leg) postabsorptively (basal) and in response to local hyperinsulinemia (0.15 mU/min/100ml leg) in 7 healthy (CTRL) and 5 T2DM older subjects. Leg blood flow and phenylalanine delivery to the leg were not different between groups, and did not change with insulin. Leg phenylalanine rate of appearance, indirect measure of muscle protein breakdown, significantly declined in both groups with no differences between groups (CTRL: 59±9 and 43±8; T2DM: 53±11and 35±5; basal vs. insulin respectively; p<0.01). Phenylalanine rate of disappearance, an indirect measure of muscle protein synthesis, tended to decrease, although not significantly, in both groups with no differences between groups (CTRL: 45±8 and 39±6; T2DM 41±9 and 28±3; basal vs. insulin respectively; p=0.056). As a result, phenylalanine net balance significantly increased in both groups with no differences between groups (CTRL: −15±2 and −3±2; T2DM: −12±4 and −6±2; basal vs. insulin, respectively; p<0.01) but remained negative, indicating ongoing protein catabolism. We conclude that T2DM does not worsen the age‐related insulin resistance of muscle proteins.