IN VIVO STUDIES OF 5-HYDROXYINDOLE METABOLISM IN PATIENTS WITH HEPATIC CIRRHOSIS AND IN RATS*†

Abstract

Widespread interest in 5-hydroxytryptamine (5-HTA) as a biologically active amine and the close association between this substance and malig- nant carcinoidosis have led to detailed studies of the 5-hydroxyindole pathway of tryptophan me- tabolism in man and experimental animals (1-3). Tryptophan is apparently hydroxylated to form the serotonin precursor, 5-hydroxytryptophan