Amino acid concentrating ability of slowly growing autochthonous hepatomas and host livers.

To examine whether an increase in the intracellular concentration of amino acids always accompanies the development of a neoplasm, slowly growing autochthonous hepatomas (originating in the place where found) were induced by feeding 0.02% acetylaminofluorene followed by 0.05% phenobarbital to Buffalo strain rats. It was found that the resulting hepatomas (123 from 43 animals) concentrated less than one half the amount of non-metabolizable alpha-aminoisobutyric acid (AIB) than did the respective host and control livers when AIB was injected 24 hrs before sacrifice. While an increase in the ability to concentrate amino acids may be necessary for rapid growth, it is not a concomitant of neoplastic transformation. The narrow range of AIB concentrations found among these 123 autochthonous tumors compared to a wide spectrum of AIB concentrations found in several transplantable Morris hepatoma lines suggests that these tumors are at one of the earliest stages of their progression.