[A study on the constitutional change of taurine and other free amino acids during the fetal development (author's transl)].

In human pregnancy, maternal and umbilical blood of the 22nd week of pregnancy and of the parturition were submitted to the analysis of total free amino acids (FAA) by amino acids analyzer. In addition, the neonatal blood was also submitted until 9 days after birth. The content of FAA in umbilical vein was higher than that of the maternal blood and it decreased at the parturition. However, the content of taurine (T) kept extremely higher level than other amino acids until term and it decreased to the normal level at 9 days after birth. In pregnant rats on day 17, 18 and 19 of gestation, the content of FAA in umbilical vein and fetal artery were 5800-7000 micrograms/dl and 5700-6250 micrograms/dl, respectively. They were two fold higher than that of maternal value. In amniotic fluid, FAA was 4100 micrograms/dl on day 18 and 8850 micrograms/dl on day 20. On the contrary, the content of T in maternal blood on day 18 was the highest value (360 micrograms /dl), and decreased to the half of the value on day 20. T in carotid artery on the same day was 1150 micrograms/dl, but it decreased to 280 micrograms/dl on day 20. In amniotic fluid, it was almost constant in the range of 380-400 micrograms/dl. When the pregnant rat was stressed by starvation, FAA was increased in both umbilical and fetal blood but it was almost constant in amniotic fluid. T was increased both in maternal and fetal blood. When the degree of starvation, T value also increased in fetal blood. From these data, we discussed on the possible mechanism of the production of T during pregnancy and after birth.