The effect of a dose of dimethylnitrosamine on the toxicity of a subsequent dose and on the toxicity of carbon tetrachloride in mice.

Mice were given a first dose of dimethylnitrosamine (DMN) and the LD50 of a second dose determined at various times later. The total dose (sum of the 2 doses) tolerated under these conditions increased slowly as the interval between the 2 doses increased, to a maximum that was maintained until the 6th day. The LD50 of the second dose then returned slowly to normal by the 10th day. The data suggest that the biochemical lesion in DMN induced liver necrosis developed relatively slowly.