Effects of N-methyl-N-nitrosourethane on DNA synthesis in the guinea pig pancreas.

The effects of N-methyl-N-nitrosourethane (NMUT) on pancreatic DNA synthesis were investigated at sequential intervals following gavage of Hartley guinea pigs with a single dose of 30 mg/kg. There was a highly significant stimulation of DNA synthesis, as evidenced by increased incorporation of [3H] methyl-thymidine ([3H]TdR), throughout the whole pancreas and particularly in the duodenal segment, at 4 h following NMUT administration, thereafter, DNA synthesis declined sharply up to 24 h, and then recovered gradually to control levels from 24--96 h. DNA synthesis stimulated by NMUT was suppressed by hydroxyurea (HU), and hence is likely to represent replicative, rather than repair, synthesis.