[Tryptophan and its metabolite concentrations in human plasma during the perinatal period]

The concentration of tryptophan (free and protein bound) and its metabolites in the plasma of the maternal vein and in the umbilical vein, umbilical artery and neonatal vein were determined by high performance liquid chromatography. The plasma levels of tryptophan and most of its metabolites in the umbilical vein and artery were significantly higher than those in the maternal vein. Especially the 3-OHAA level in umbilical blood was approximately 50 times as high as that in maternal blood. The concentration of total tryptophan in the plasma of the neonatal vein showed a marked decrease at one day after birth in comparison with that at birth, but the total kynurenine concentration was not decreased in the plasma of the neonatal vein. In the blood, ratios of free to total tryptophan and kynurenine were kept at a constant level throughout the perinatal period. In conclusion, the present study suggests that tryptophan metabolism may play an important role in fetal development.