Placental transfer of phenylalanine in Macaca mulatta and Macaca fascicularis.

We investigated placental transport mechanisms of phenylalanine in Macaca mulatta and Macaca fascicularis. In the beginning of the third trimester we administered i.v. phenylalanine and p-chlorophenylalanine to pregnant animals. Initial higher phenylalanine concentrations were observed followed by a rapid decrease in both rhesus mothers and fetuses when compared with phenylalanine levels in fascicularis mothers and fetuses. In general, however, placental transfer mechanisms of phenylalanine did not differ significantly between the two species.