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Table 4 Plasma phenylalanine concentrations and enrichments and muscle free and protein-bound phenylalanine enrichments during basal, postabsorptive conditions and during the hyperinsulinemic-hyperaminoacidemic clamp in young and old women

From: Sexually dimorphic effect of aging on skeletal muscle protein synthesis

Time (min) Concentration Enrichment
  (μM) Muscle protein bound TTR Muscle free TTR Plasma TTR
  Young Old Young Old Young Old Young Old
Basal conditions       
60 63 ± 3 60 ± 3 0.000057 ± 0.000015 0.000062 ± 0.000017 0.0602 ± 0.0032 0.0622 ± 0.0052 0.0906 ± 0.0038 0.0862 ± 0.0027
90 64 ± 6 61 ± 2 --- --- --- --- 0.0986 ± 0.0048 0.0893 ± 0.0039
120 56 ± 3 54 ± 2 --- --- --- --- 0.1009 ± 0.0015 0.0952 ± 0.0040
150 56 ± 5 64 ± 3 --- --- --- --- 0.0998 ± 0.0031 0.0967 ± 0.0043
180 59 ± 2 60 ± 4 --- --- --- --- 0.1038 ± 0.0034 0.1013 ± 0.0038
210 63 ± 3 62 ± 4 --- --- --- --- 0.1041 ± 0.0029 0.1020 ± 0.0043
240 66 ± 2 65 ± 4 0.000147 ± 0.000015 0.000176 ± 0.000020 0.0722 ± 0.0040 0.0673 ± 0.0045 0.1023 ± 0.0024 0.1026 ± 0.0039
Δ (240 – 60 min) 0.000090 ± 0.000014 0.000114 ± 0.000012     
Mean 61 ± 3 61 ± 3    0.0662 ± 0.0035 0.0648 ± 0.0044 0.1000 ± 0.0027 0.0962 ± 0.0035
Hyperinsulinemic-hyperaminoacidemic clamp      
270 111 ± 10 92 ± 4 --- --- --- --- 0.1027 ± 0.0045 0.1013 ± 0.0086
300 108 ± 8 111 ± 7 --- --- --- --- 0.0950 ± 0.0024 0.1026 ± 0.0065
330 122 ± 16 106 ± 7 --- --- --- --- 0.0926 ± 0.0020 0.0894 ± 0.0069
360 124 ± 14 122 ± 9 --- --- --- --- 0.0944 ± 0.0032 0.0922 ± 0.0035
390 128 ± 11 109 ± 5 --- --- --- --- 0.0970 ± 0.0029 0.0838 ± 0.0063
420 120 ± 5 114 ± 3 0.000305 ± 0.000020 0.000348 ± 0.000027 0.0752 ± 0.0019 0.0782 ± 0.0033 0.0971 ± 0.0026 0.0929 ± 0.0038
Δ (420 – 240 min) 0.000157 ± 0.000016 0.000171 ± 0.000017     
Mean 119 ± 10 109 ± 4    0.0737 ± 0.0028 0.0727 ± 0.0034 0.0965 ± 0.0024 0.0937 ± 0.0046
  1. Values are means ± SEM.