Effect of various factors on the induction of liver tumors in animals by quinoline.

Tumorigenic effect of a diet containing quinoline on the liver of various animals and the synergistic or antagonistic effect by other chemicals on quinoline hepatocarcinogenesis in rats were examined. It was concluded that 4,4'-diaminodiphenylmethane (0.1%) and 3-methylcholanthrene (0.0067%) had a significant inhibitory effect on liver carcinogenesis due to quinoline in rats, but 1-naphthyl isothiocyanate (0.06%) and p-hydroxypropiophenone (1.0%) had no inhibitory effect in the present observations. Transmission electron-microscopic study demonstrated the fine structure of vascular tumors induced by quinoline. On the other hand, it was found that quinoline induced liver tumors in both sexes of mice and rats but not in hamsters or guinea pigs. Male rats were more susceptible than females to the tumorigenic action of quinoline, and mice showed the least susceptibility. Histological changes in the liver of rats or mice induced by quinoline were clasified as hemangioendotheliomas or hemangiosarcomas and hepatocellular carcinomas. Several rats treated with quinoline had hemangiosarcomatous metastatic foci in the lung.