[Kinetics of macromolecular carbamoylation in normal and tumor cells after the administration of N-methyl-N-nitrosourea-14CO].

The pharmacokinetics of N-methyl-N-nitrosourea-14CO (14CO-MNU) was investigated in hepatoma 22a tumor-bearing and normal mice at various time after a single intravenous injection (80 mg/kg). The rapid clearance of 14CO-MNU from plasma of the mice was observed 5 hours following the administration of the drug. Peak levels of radioactivity in the hepatoma were noted 48 hours after the administration of 14CO-MNU, while the liver, kidney, spleen and intestinal epithelium showed an insignificant radioactivity at this time both in normal and tumor-bearing mice. The analysis of the radioactivity distribution among macromolecules (DNA, RNA, protein) and lipids indicated the highest label in lipids of all organs.