Distribution of bound tritium from 3H-diethylnitrosamine in rat tissues

The concentration of bound ³H from diethyl-(mono-2-³H)-nitrosamine was determined in five different rat tissues as a function of time after single and repeated oral doses of the labelled carcinogen. The recorded curves can be described as two-component kinetics. Whereas the first component decreased with a half-life of about 3–6 h, the corresponding value for the second component was approximately 90 h. Two hundred and forty hours after a single ³H-DEN dose, the highest relative concentration of bound ³H was recorded in the liver (1.00), followed by kidney (0.74), spleen (0.40), small intestine (0.18), and lung (0.14). The capacity of the liver to metabolically activate DEN, as reflected by the tissue-specific accumulation of bound ³H after repeated ³H-DEN doses, was not impaired at an advanced stage of hepatocarcinogenesis by DEN.