Phenobarbital as a promoter in the initiation/selection process of experimental rat hepatocarcinogenesis

Supplementary introduction of a phenobarbital (PB) promotionstep after the Solt and Farber procedure dramatically increasesthe number of phenotypically-altered hepatocytes. These hepatocytesoccupy {small tilde}40% of the liver volume after one week ofPB treatment. These areas constitute a relatively uniform cellularpopulation with altered histological pheno-type and with distincthistochemicai markers used by other authors for the detectionof premalignancy. This procedure leads to the appearance ofnumerous hepatocellular carcinomas at approximately the 36 weeksstage. It was suggested that the early hepatocellular alterationsafter the initiation/selection procedure followed by PB mightcorrespond to the hyperplasia of phenotypically-altered epidermalcells at the conversion step of mouse skin tumor promotion.