Effect of dimethylnitrosamine upon carbamoyl phosphate and ornithine utilization in rat liver

Newborn CFY rats were intraperitoneally treated with a single dose of dimethylnitrosamine. Changes in the activity of carbamoyl-phosphate synthase I and II, ornithine carbamoyltransferase, aspartate carbamoyltransferase and dihydroorotase, i.e. utilization of ornithine and carbamoyl-phosphate pools were followed for 300 days. One or two months after treatment the activity of enzymes which utilize ornithine and carbamoyl-phosphate was enhanced in the cytosol, whereas the activity of the intramitochondrial enzymes in urea synthesis was decreased. Changes in the utilization of ornithine and carbamoyl-phosphate pools, characteristic of proliferating tissues, appeared to be irreversible.