We have demonstrated that there is a dose-related increase in the excretion of 7-[methyl-14C]methylguanine ( [14C]m7Gua) following p.o. administration of di[methyl-14C]methylnitrosamine to rats. Urine was collected for 24 hr after di[methyl-14C]methylnitrosamine administration, and the purines were precipitated from an aliquot of the urine with silver nitrate. Purines were released from the pre...

An alkaline elution assay previously used to detect single-strand breaks in DMA of cultured mammalian cells has been modified to allow the analysis of DMA damage in various organs of rats following exposure to chemical carcinogens. Prior to exposure, the DMA of neonatal animals was labeled with [3H]thymidine. DNA damage was assessed in liver, lung, thymus, brain, kidney, stomach, duodenum, colo...

After severe hepatic injury induced by dimethylnitrosamine, approximately a 4-fold increase in hepatic prolyl 4-hydroxylase activity occurred within 4 days, whereas the increases in total immunoreactive prolyl 4-hydroxylase protein and in prolyl 3-hydroxylase activity were only about 1.4-fold. The different magnitudes of the increases in the prolyl 4-hydroxylase and 3-hydroxylase activities wer...

The effect of age at treatment on the incidence and type of kidney tumor induced by dimethylnitrosamine was investigated in an established model of experimental renal carcinogenesis. Groups of Potion albino Wistar rats were dosed with carcino gen at 24 hr; at 3 weeks; and at i , i .5, 2, 3, 4, and 5 months of age. In all groups except the neonates, the animals were preconditioned by feeding a n...