[Role of carbamoylation processes in the cytotoxic action of nitrosoalkylureas].

The treatment of an asynchronous LL cell line population, being in the log phase of growth, with isocyanate (one of the nitrosourea degradation products) results in the cell death of about 50% of the whole population. The other part of this cell population is unsensitive to this chemical, even at concentrations 100 times more than those equal the LD50 doses. The cell death is due neither to inhibition of DNA-synthesis nor to DNA (single or double strand) breaks or DNA-membrane complex degradation. It is assumed that a mechanism highly sensitive to carbomoylation may be operating in some period of the cell cycle.