Table 2.

Rates of protein synthesis (% h⁻¹) in mixed muscle protein and myofibrillar, mitchondrial and sarcoplasmic fractions of muscle before and during infusion of mixed amino acids at four different rates

	Amino acid infusion rate (mg kg−1 h−1)
	43.5	87	162	261
Mixed muscle protein
Before infusion	0.057 ± 0.008	0.086 ± 0.009	0.076 ± 0.008	0.054 ± 0.002
During infusion	0.068 ± 0.007	0.134 ± 0.021	0.130 ± 0.029	0.1 ± 0.01
% Change	+30 ± 25	+57 ± 17	+72 ± 38	+88 ± 20
Myofibrillar
Before infusion	0.059 ± 0.014	0.083 ± 0.023	0.085 ± 0.017	0.049 ± 0.005
During infusion	0.065 ± 0.014	0.101 ± 0.018	0.174 ± 0.036	0.095 ± 0.016
% Change	+17 ± 27	+40 ± 32	+111 ± 43	+93 ± 15
Mitochondrial
Before infusion	0.053 ± 0.007	0.066 ± 0.015	0.119 ± 0.044	0.043 ± 0.006
During infusion	0.064 ± 0.006	0.113 ± 0.009	0.175 ± 0.046	0.086 ± 0.016
% Change	+33 ± 27	+90 ± 40	+88 ± 109	+112 ± 28
Sarcoplasmic
Before infusion	0.067 ± 0.009	0.072 ± 0.015	0.108 ± 0.018	0.065 ± 0.009
During infusion	0.079 ± 0.008	0.127 ± 0.016	0.161 ± 0.017	0.134 ± 0.014
% Change	+30 ± 24	+80 ± 15	+57 ± 16	+140 ± 63

Values are means ± s.e.m. for 4–6 subjects (see Rennie et al. 1982 for method of fractional synthesis rate calculation). All of the rises in protein synthesis were significant at P < 0.05 compared to basal values.