Relation between the incorporation of 5-fluorouracil into liver carcinoma and normal tissue RNA at hepatic arterial administration in the rat is altered by overnight starvation.

The cytotoxicity of 5-FUra has been related to its incorporation into RNA. In a model of secondary liver cancer in the rat, the incorporation of 5-FUra into the acid-soluble fraction, RNA and DNA of several normal tissues and an adenocarcinoma of the colon transplanted to the liver was determined. A therapeutic labelled dose of the drug was infused via the hepatic artery for 2 hr and the rats killed 1 hr later. Half of the rats were starved overnight before treatment. The incorporation of 5-FUra into liver and intestinal RNA increased at starvation. It was unchanged in kidney and bone marrow. The incorporation into tumor RNA decreased insignificantly. The incorporation into tumor RNA was significantly higher than in hepatic, intestinal, and renal RNA at ad libitum feeding. This difference disappeared at overnight starvation.