Carcinogenic activity of quinoline on rat liver.

The effects of prolonged p.o. administration of quinoline or 2-chloroquinoline on rat liver were examined histologically. Hepatocellular carcinomas and hemangioendotheliomas were observed in the livers of rats fed a basal diet containing 0.05, 0.10, or 0.25% quinoline for about 16 to 40 weeks. However, no neoplastic changes were seen in the livers of rats fed a basal diet containing 0.05, 0.10, or 0.25% 2-chloroquinoline for 40 weeks. In groups that received low concentrations of quinoline, the incidences of hepatocellular carcinomas were higher and the incidences of hemangioendotheliomas were lower than in the group that received a high concentretion of quinoline. The liver tumors induced by quinoline were classified histologically as hemangioendotheliomas or hemangiosarcomas and trabecular hepatocellular carcinomas. Typical nodular hyperplasias were occasionally seen in the livers of rats treated with quinoline. 2-Chloroquinoline did not induce any nodular hyperplasia or other neoplastic changes, but it caused diffuse fatty changes of parenchymal cells. Oval cell infiltration and bile duct proliferation were slight or moderate. Cirrhotic changes were rare in the livers of rats treated with either quinoline or 2-chloroquinoline. The serum levels of glutamic oxaloacetic transaminase and alkaline phosphatase were slightly changed in groups treated with quinoline, but no other remarkable changes were detected.