Metabolic Adaptations in Rat Hepatomas. Vi. Substrate-hormone Relationships in Tryptophan Pyrrolase Induction.

The failure of induction of tryptophan pyrrolase (TP) in the majority of hepatomas after the administration of substrate or hormone was shown probably to be the result of a basic defect in the tumor cell itself, and not of the lowered blood flow or the lack of portal blood supply to the tumor. Two exceptions, Hepatomas H-35 and 7793, were shown to have a significant sub strate induction in the intact but not in the adrenalectomized host. The absence of "pure" substrate induction in these heptomas was interpreted in the