Effect of chemical carcinogens on pancreatic DNA synthesis in vivo.

The effect of dimethylnitrosamine (DMN), ethionine, streptozotocin, N-methyl-N-nitrosourethan (MNUT), N-bis(2-hydroxypropyl)nitrosamine (DHPN), azaserine, and 4-hydorxyaminoquinoline 1-oxide (4-HAQO) on DNA synthesis after partial pancreatectomy was studied. Its results indicates that DNA synthesis of the residual pancreas occurred and reached the maximum value at 3 days and returned to the control value 12 days after the operation. DNA synthesis, which was inhibited 96.7% by hydroxyurea 3 days after the operation, indicated that semi-conservative DNA synthesis had occurred in the residual pancreas. DMN and ethionine, non-pancreatic carcinogens, did not inhibit while DHPN, MNUT, azaserine, and 4-HAQO, pancreatic non-endocrine carcinogens, inhibited DNA synthesis in the rat pancreas by 57.9, 76.4, 71.7, and 82.1%, respectively. The effect of streptozotocin, pancreatic endocrine carcinogen, on DNA synthesis was not clear from the present experiment. Further effect on the inhibition of DNA synthesis by these carcinogens was obtained by dose-response studies and its results indicated that there was a correlation between pancreatic carcinogens and the inhibition of DNA synthesis after partial pancreatectomy in rats.