EFFECT OF PHENOBARBITAL ON INDUCTION OF LIVER AND LUNG-TUMORS BY DIMETHYLNITROSAMINE IN NEWBORN MICE

Abstract

The effect of phenobarbital on simultaneous induction of liver and lung tumors was examined in inbred DDD mice. Group 1 of newborn mice received a single i.p. injection of dimethylnitrosamine (DMN) and after weaning were given 0.05% phenobarbital solution to drink. Group 2 mice received an injection of DMN like group 1 but were then given normal water. Group 3 mice were injected i.p. with 0.9% NaCl solution and then given phenobarbital solution to drink as in group 1. Group 4 mice were injected with 0.9% NaCl solution like group 3 and then given tap water to drink. The animals were examined 16 wk after birth. In group 1, 27 of 35 mice (77%) had liver tumor and 15 (43%) had lung tumor. In group 2, 8 of 24 mice (33%) had liver tumor and 16 (67%) had lung tumor. Animals in groups 3 and 4 did not develop tumors. The difference in the incidences of liver tumor, but not lung tumor, in groups 1 and 2 was statistically significant (P < 0.01); that is, a promoting effect of phenobarbital was observed in induction of liver tumor, but not lung tumor.