Static and dynamic aspects of amino acid pools in rat liver and Morris hepatomas 9618A and 7800.

Although pool sizes for a number of amino acids in the Morris hepatomas 9618A and 7800 were found to be similar to those of host liver, deviations existed in the levels of certain free amino acids that were studied. Most often the differences tended toward lower values in the tumor. A notable exception was the high level of lysine in the 96ISA hepatoma. Leucine levels were equal to those of the host liver in the case of the 9618A hepatoma and lower in the 7800 hepatoma. The decay rates of carboxyl-labeled leucine from acid-soluble pools and microsomal protein of the 7800 hepatoma were the same as those of host liver acid-soluble pools and microsomal protein. A much slower decay rate was found in the acid-soluble pool of the 9618A hepatoma when compared to the host. These experimental findings point to (a) a possible relationship between a reduced degradation of protein and the mainte nance of a sequestered pool of amino acids and (¿>) the fact that unusual decay rates of labeled constituents of a pool may not be reflected by the pool size alone.