Altered tryptophan and alanine transport in fibroblasts from boys with attention-deficit/hyperactivity disorder (ADHD): an in vitro study

Table 1 Kinetic parameters of tyrosine, tryptophan and alanine transport in fibroblasts from ADHD children

Kinetic parameter	Amino acid	Children with ADHD (n = 14)	Controls (n = 13)	p-value
V _max	Tyrosine	15.1 (11.5-25.4)	15.5 (7.8-21.5)	0.617
	Tryptophan	1.5 (1.1-3.0)	2.0 (1.3-4.7)	0.039*
	Alanine	42.8 (36.3-64.9)	32.0 (22.7-63.4)	0.031*
K _m	Tyrosine	20.0 (6.3)	18.8 (5.5)	0.645
	Tryptophan	13.6 (4.7)	21.1 (8.2)	0.010**
	Alanine	125.7 (41.2)	100.7 (30.1)	0.086

The results are presented as median (range) for V _max values and as mean (standard deviation) for K _m values. ADHD, indicates Attention Deficit/Hyperactivity Disorder, V _max , indicates maximal transport capacity (nmol/min/mg protein) and K _m , indicates affinity of binding sites for a specific amino acid (μmol/l). *Statistically significant (p ≤ 0.05) **Statistically significant (p ≤ 0.01)

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