Dhondt J L, Ardouin P, Hayte J M, Farriaux J P
Clin Chim Acta. 1981 Oct 26;116(2):143-52. doi: 10.1016/0009-8981(81)90017-6.
Large variations of pteridine elimination occur in childhood, due to the ontogenic development of the metabolism of tetrahydrobiopterin. The main feature is the slow maturation of biopterin synthesis whereas neopterin synthesis is high at birth; thus a high neopterin to biopterin ratio (4.4 +/- 2.1) occurs in the neonatal period, a ratio which then decreases to adult values (0.5 +/- 0.2). Comparing pteridine elimination of PKU patients with that of controls of the same age, a high excretion of biopterin and, to a lesser extent, of neopterin is found. In normal subjects, following an oral phenylalanine load, biopterin levels in urine and serum also increase, whereas variations of neopterin concentration are small. In rats, phenylalanine also leads to an increase of serum biopterin whereas liver biopterin decreases. This suggests that the main explanation for the biopterin increase in serum and in urine by phenylalanine is a release of the intracellular biopterin by the aminoacid.
由于四氢生物蝶呤代谢的个体发育，儿童期蝶呤消除存在很大差异。主要特征是生物蝶呤合成成熟缓慢，而新蝶呤合成在出生时较高；因此，新生儿期新蝶呤与生物蝶呤的比例较高（4.4±2.1），随后该比例降至成人水平（0.5±0.2）。将苯丙酮尿症患者的蝶呤消除情况与同龄对照组进行比较，发现生物蝶呤排泄量较高，新蝶呤排泄量在较小程度上也较高。在正常受试者中，口服苯丙氨酸负荷后，尿液和血清中的生物蝶呤水平也会升高，而新蝶呤浓度变化较小。在大鼠中，苯丙氨酸也会导致血清生物蝶呤增加，而肝脏生物蝶呤减少。这表明，苯丙氨酸导致血清和尿液中生物蝶呤增加的主要原因是氨基酸使细胞内生物蝶呤释放。
