Rapid and selective induction of erythroleukemia in female Donryu rats by continuous oral administration of 1-ethyl-1-nitrosourea.

Three groups of female Donryu rats were given continuously 1-ethyl-1-nitrosourea, 400, 200, or 100 mg/liter, in their drinking water. Leukemias developed in 94 of 104 (92%) rats surviving more than 6 experimental weeks. Of the leukemias, the erythroleukemias were induced most frequently, rapidly, and selectively. Other types of leukemias were found in a few rats of the high-dose group and, in some cases, in rats of the low-dose group. Tumors were also induced in the digestive tract, mammary glands, ear duct, and other organs, but their incidences were lower than 24%.