Ethylene dibromide as a mitogen for liver.

Intubation of ethylene dibromide (7.5 to 10 mg. per 100 gm. of body weight) into the stomach of nonfasted Wistar rats induces DNA synthesis and cell division in the liver. The peak of DNA synthesis, as measured by 3H-methyl thymidine incorporation, was attained at or shortly after 24 hours. The mitotic waves measured with the aid of colchicine occurred at 24 to 30 hours and 48 to 54 hours after ethylene dibromide treatment. Approximately 16 per cent of liver cells entered mitosis. The increase in DNA synthesis was confirmed by autoradiography. The stimulation of liver cell mitosis occurs in nonfasted animals without apparent cell necrosis. Thus, ethylene dibromide appears to be an effective mitogen for liver under some experimental conditions. The possible relationship between the mitogenic effect at a low dosage range and necrosis at a higher range is discussed.