Table 2.

Leg muscle phenylalanine kinetics

Parameters	Adult	Children	P
Delivery to the leg	1,007 ± 720	1,379 ± 942	0.12
Release from the leg	1,051 ± 763	1,370 ± 948	0.18
Transport into the muscle	196 ± 168	308 ± 275	0.10
Transport from the muscle	239 ± 197	299 ± 283	0.39
A-V shunting	811 ± 595	1,071 ± 776	0.18
Muscle protein breakdown rate	179 ± 115	184 ± 124	0.82
Muscle protein synthesis rate	134 ± 96	192 ± 128	0.07
Net balance	−43 ± 61	8 ± 68	<0.05
Muscle protein FSR (%/h)	0.11 ± 0.05	0.16 ± 0.10	0.02

Data are presented as mean ± SD. Units for measurements calculated using the three-pool model are presented in nanomoles of phenylalanine per minute per 100 ml of leg volume (nmol Phe/min/100 ml leg volume); FSR data are presented in percent per hour (%/h)

A-V arteriovenous, FSR fractional synthesis rate