Experiments on the influence of combined application of N-methylnitrosourea and 7,12-dimethylbenzanthracene in female Sprague-Dawley rats.

In a syncarcinogenesis experiment 144 female Sprague-Dawley rats were given combinations of 0, 5, 15 of 30 mg/kg methylnitrosourea intravenously and 0, 10, 30 of 60 mg/kg 7,12-dimethylbenzanthracene perorally. Despite identical organotropism of both compounds an increased carcinogenic effect was observed in the low dose range only where as the high doses of methylnitrosourea inhibited the manifestation of tumors after 7,12-dimethylbenzanthracene.