REGULATION OF FETAL AMINO-ACID-METABOLISM - SUBSTRATE OR HORMONAL-REGULATION

Insulin is regarded as the primary fetal growth-promoting hormone, bur direct in vivo experimental data supporting this conjecture are spars e. Data obtained from studies in in vivo, chronically catheterized fet al lambs under a variety of experimental circumstances demonstrate tha t glucose availability is the primary modulator of fetal protein accre tion, via its ability to diminish amino acid catabolism. The ovine fet us is shown to be resistant to insulin-induced suppression of proteoly sis, relative to the adult. Data from studies in the human premature i nfant show that the findings in the ovine fetus are similar to those i n the ex utero premature human.