The rate of breakdown of methyl methanesulphonate, dimethyl sulphate and N-methyl-N-nitrosourea in the rat.

1. The rates of decomposition of methyl methanesulphonate, dimethyl sulphate and N-methyl-N-nitrosourea in the rat were measured. 2. Dimethyl sulphate is no longer detectable in the blood of the rat 3min. after an intravenous dose (75mg./kg. body wt.). Methyl methanesulphonate is only just detectable in the blood 1(1/2)hr. after an intravenous dose (100mg./kg. body wt.). N-Methyl-N-nitrosourea is no longer detectable in the blood 15min. after an intravenous dose (100mg./kg. body wt.). 3. The exhalation of (14)CO(2) after an intragastric dose of N[(14)C]-methyl-N-nitrosourea (100mg./kg. body wt.) is appreciably slower than after an intravenous dose, from which it is estimated that the lifetime in the rat is 2-3hr.