. 2010 Aug 19;59(11):2764–2771. doi: 10.2337/db10-0415

TABLE 3.

Leg free phenylalanine concentrations, enrichments, and kinetics in two groups of healthy older subjects at baseline and during local insulin infusion in one leg with (SNP) or without (Control) concomitant infusion of the vasodilator sodium nitroprusside

	Control		SNP
	Basal	Insulin	Basal	Insulin
Phenylalanine concentration (μmol/l)
Femoral artery	63 ± 3	61 ± 4	62 ± 3	63 ± 3
Femoral vein	70 ± 3	62 ± 4^*	68 ± 4	59 ± 4^*
Muscle	80 ± 10	65 ± 10^*	79 ± 4	67 ± 4^*
Phenylalanine enrichment (tracer/tracee, %)
Femoral artery	8.9 ± 0.5	9.9 ± 0.2^*	9.1 ± 0.4	10.0 ± 0.1^*
Femoral vein	6.6 ± 0.4	7.7 ± 0.2^*	6.9 ± 0.3	8.4 ± 0.2^*
Muscle	5.6 ± 0.2	6.9 ± 0.5^*	5.8 ± 0.3	7.2 ± 0.6^*
Phenylalanine kinetics (nmol · min⁻¹ · 100 ml leg⁻¹)
Net balance	−17 ± 3	−2 ± 3	−15 ± 3	26 ± 12^*^,^†
Delivery to the leg	162 ± 31	196 ± 28	151 ± 31	346 ± 39^*^,^†
Output from the leg	179 ± 32	198 ± 27	166 ± 34	321 ± 33^*^,^†
Leg rate of appearance	53 ± 10	54 ± 7	47 ± 9	69 ± 13
Leg rate of disappearance	36 ± 9	52 ± 9	32 ± 6	94 ± 23^*^,^†
Transport into the muscle	115 ± 28	168 ± 37	103 ± 23	225 ± 46^*
Transport out of the muscle	132 ± 28	170 ± 35	118 ± 26	200 ± 38^*
Release from proteolysis	58 ± 12	60 ± 8	53 ± 9	81 ± 12^*
Utilization for protein synthesis	42 ± 10	58 ± 10	38 ± 6	107 ± 23^*^,^†
Intracellular availability	173 ± 36	227 ± 40	156 ± 31	307 ± 58^*
Recycling	6 ± 2	6 ± 5	6 ± 2	13 ± 2^*

Data are mean ± SE.

*P < 0.05 vs. basal;

† indicates group × time effect (P < 0.05).