The Relationship between Tryptophan Level in Serum and its Hepatic Uptake in Rats with Injured Liver by Carbon Tetrachloride

We have studied the relationship between the changes in tryptophan (free type and albumin bound type) in serum and its uptake in rat liver injured by i. p. administration of carbon tetrachloride. Total tryptophan concentration in serum remained high throughout the liver injury. Its high level was caused by elevation of free tryptophan resulting from a decrease In serum total protein, especially albumin, and a increase in free fatty acids. Hepatic uptake of tryptophan at high affininity sites (low Km) was impaired by liver injury, but that at low affinity ones (high Km) was not. A high level of tryptophan in serum should aid its hepatic uptake when the number of uptake sites on the liver cells surface is decreased because of liver injury.