Table 3.

Concentrations of amino acids in plasma of WT and PKU mice fed diets containing casein, GMP, or amino acids

	WT Mice			PKU Mice			ANOVA P Value
Amino Acid	Casein	Amino Acid	GMP	Casein	Amino Acid	GMP	Genotype	Diet	Sex	Genotype × Diet
N	15	13	13	14	15	14
Alanine	754 ± 62	1,021 ± 97	874 ± 110	755 ± 67	952 ± 112	716 ± 63		0.0364
Arginine	95 ± 4	93 ± 12	83 ± 6	73 ± 5	87 ± 3	79 ± 4	0.0087		0.0063
Aspartate	14 ± 2	11 ± 1	13 ± 2	10 ± 1	7 ± 1	8 ± 1	0.0033
Citrulline	76 ± 5	68 ± 6	75 ± 6	78 ± 5	70 ± 3	64 ± 5			0.0350
Cysteine	17 ± 5	6 ± 3	5 ± 3	9 ± 4	5 ± 3	2 ± 2		0.0244
Glutamate	29 ± 2	32 ± 5	41 ± 8	28 ± 2	27 ± 2	40 ± 3		0.0009	0.0333
Glutamine	474 ± 16	533 ± 42	661 ± 82	434 ± 27	475 ± 26	541 ± 25	0.0337	<0.0001
Glycine	214 ± 10	886 ± 126	188 ± 8	179 ± 7	785 ± 127	183 ± 8	0.0119	<0.0001
Histidine	73 ± 3	67 ± 4	81 ± 14	82 ± 4	69 ± 5	76 ± 2
Isoleucine	110 ± 8c,d	83 ± 9d	243 ± 30a	134 ± 12c	95 ± 7c,d	185 ± 24b		<0.0001		0.0355
Leucine	162 ± 12	113 ± 11	148 ± 11	186 ± 20	134 ± 10	127 ± 5		0.0003
Lysine	437 ± 25	447 ± 51	372 ± 28	415 ± 35	470 ± 39	339 ± 24		0.0187	0.0032
Methionine	77 ± 6	114 ± 16	148 ± 46	75 ± 7	89 ± 12	88 ± 13
Ornithine	61 ± 4	75 ± 9	65 ± 9	67 ± 5	59 ± 4	55 ± 4
Phenylalanine	51 ± 2c	36 ± 4d	41 ± 4d	2,103 ± 92a	722 ± 26b	766 ± 18b	<0.0001	<0.0001		0.0397
Proline	157 ± 20	90 ± 12	242 ± 53	203 ± 32	81 ± 12	167 ± 28		<0.0001
Serine	165 ± 10	271 ± 24	205 ± 35	180 ± 11	252 ± 13	157 ± 12		<0.0001
Taurine	500 ± 30	589 ± 69	561 ± 40	417 ± 24	488 ± 36	489 ± 35	0.0097		0.0245
Threonine	317 ± 23	409 ± 53	971 ± 125	305 ± 24	384 ± 37	807 ± 98		<0.0001
Tryptophan	61 ± 4	75 ± 10	72 ± 7	64 ± 25	52 ± 4	65 ± 4	0.0033	0.0040
Tyrosine	102 ± 11	57 ± 12	71 ± 17	50 ± 7	22 ± 3	19 ± 3	<0.0001	<0.0001
Valine	315 ± 23	219 ± 17	401 ± 42	352 ± 28	227 ± 14	333 ± 31		<0.0001
BCAA	587 ± 42	415 ± 32	792 ± 80	672 ± 60	456 ± 28	644 ± 55		<0.0001

Values are means ± SE in μmol/l; n, no. of mice. WT, wild type; PKU, phenylketonuria; BCAA, branched chain amino acid. There was a significant genotype effect where WT mice had higher plasma concentrations of arginine, aspartate, glutamine, glycine, taurine, tryptophan, and tyrosine compared with homozygous mice. The amino acid diet resulted in higher values for alanine, glycine, and serine compared with casein and GMP. Both amino acid and casein diets had higher values for lysine compared with GMP. The casein diet resulted in higher plasma cysteine than GMP, but not amino acid diet. GMP had higher plasma tryptophan than casein, but not amino acid diet. Casein resulted in higher plasma leucine and tyrosine than both GMP and amino acid diets. Both casein and GMP diets resulted in higher plasma proline, valine, and BCAA than the amino acid diet. The GMP diet resulted in higher plasma glutamate, glutamine, and threonine compared with both the casein and amino acid diets. Females have higher plasma levels of arginine, citrulline, lysine, and taurine, and males have higher plasma glutamate. There was a significant genotype by diet interaction for isoleucine and phenylalanine. ^a,b,c,dMeans in a row with superscripted letters without a common letter differ, P < 0.05. BCAA, sum of isoleucine, leucine, and valine. P values not listed are nonsignificant.