Effect of guanidinoethyl sulfonate on taurine concentrations and fetal growth in pregnant rats.

Guanidinoethyl sulfonate (GES), a transport antagonist of taurine, was given to pregnant rats from day 11 to 21 of gestation as a 1% solution in drinking water. On day 21 of gestation in GES-treated pregnant rats, the concentration of taurine markedly decreased in the fetal whole body (54% of the control), the fetal liver (37%), the fetal whole brain (87%), the placenta (32%), the maternal liver (33%), the maternal whole brain (32%), and the maternal plasma (46%). The wet weight of fetal whole body, liver and brain of fetus, and placenta also showed a significant drop. But there were no differences of weight gain, in the liver and brain weights of the mother of the control and GES-treated pregnant rats. The urinary excretion of taurine in pregnant rats treated with GES was much higher than that of the controls. These results suggest that the administration of GES to pregnant rats induces much urinary taurine excretion with a resulting decrease in the tissue taurine content and readily produces taurine-deficient fetal rats.