H. Sidransky et E. Verney, EFFECT OF AMINO-ACID IMBALANCES ON THE STIMULATORY EFFECT OF L-TRYPTOPHAN ON HEPATIC PROTEIN-SYNTHESIS, Amino acids, 12(3-4), 1997, pp. 205-212
Earlier it was reported that mice or rats tube-fed a single feeding of
L-tryptophan (TRP) demonstrated a stimulation of hepatic protein synt
hesis. The present study was concerned with whether dietary imbalances
induced by tube-feeding different ratios of L-alanine (ALA) or L-leuc
ine (LEU) in relation to TRP would affect TRP's stimulatory effect on
hepatic protein synthesis. Male Swiss mice, food-deprived overnight, w
ere tube-fed one feeding of solution keeping TRP constant and varing r
atios of ALA/TRP of 0.4, 2.1, or 4 or ratios of LEU/TRP of 4.8, 7.2, o
r 9.6. After 1 h, mice were killed and protein synthesis (C-14-leucine
incorporation into proteins in vitro using microsomes of livers) was
measured. TRP alone stimulated hepatic protein synthesis by 83% while
ALA/TRP ratios of 2.1 or 4 but not of 0.4 and LEU/TRP ratios of 9.6 bu
t not of 4.8 or 7.2 caused significant decreases in the stimulation of
hepatic protein synthesis. Measurements of serum and hepatic free TRP
concentrations in the experimental groups were similar in all groups
tube-fed TRP alone or in combinations.