THE EFFECTS OF TUMOR-GROWTH ON CIRCULATING AMINO-ACIDS IN THE LATE PREGNANT RAT

The implantation of a rapidly-growing tumour - the AH-130 Yoshida asci tes hepatoma - to late pregnant rats resulted in important changes in both the maternal and fetal amino acid concentrations. Increased conce ntrations of most amino acids - glycine, alanine, threonine, serine, p roline, glutamate + glutamine, valine, leucine, isoleucine, phenylalan ine, tyrosine and lysine - are found in the fetal circulation, the con centration of total and essential amino acids being clearly higher tha n in the non-tumour bearing controls. In the maternal circulation, the presence of the tumour also caused increases in the concentration of glycine, lysine, glutamate + glutamine and arginine. Conversely, tumou r-bearing rats had lower concentrations of threonine, serine, aspartat e + asparagine, valine, leucine, phenylalanine and histidine. These re sults support the described increased fetal availability of amino acid s during tumour growth (Carbo, N., Lopez-Soriano, F.J. and Argiles, J. M. (1994) In the late pregnant rat, tumour growth results in an increa sed availabilty of fetal amino acids. Biochem. J., in press) and allow us to suggest that important changes in placental amino acid transpor t systems must be induced by tumour burden.