Enhancing effect of barbital on N-2-fluorenylacetamide-induced rat liver lesions.

The enhancing effect of phenobarbital (PB) and barbital on hepatotumorigenesis were compared by quantitative analysis of the behavior of altered foci following discontinuation of N-2-fluorenylacetamide (FAA) administration. Thirty-four male ACI rats, 2 months old, were fed 0.02% FAA diet for 13 weeks and some of them were sacrificed immediately. The remaining rats were divided into three groups and given a basal diet (group I) or 0.05% PB diet (group II) or 0.05% barbital diet (group III) and sacrificed sequentially at 8 and 16 weeks after the beginning of administration of each diet. The number of altered foci detected in hematoxylin and eosin stained or iron stained specimens per cm2 of the liver space at 16 weeks in group I was much lower than that at termination of FAA feeding. However, the numbers in groups II and III were well maintained at 8 and 16 weeks and those at 16 weeks in both groups were significantly higher than that in group I (P less than 0.001). These data show that barbital could be an enhancer of hepatotumorigenesis like PB.