Biotransformation and intracellular binding of arsenic in tissues of rabbits after intraperitoneal administration of 74As labelled arsenite.

The fate of arsenite was studied in rabbits injected i.p. with 1 microgram As/kg body wt as 74As labeled AsO2-. Eight tissues plus plasma and urine were analyzed for 74As content at different times. Arsenic was rapidly metabolized and poorly retained in the tissues. The main metabolite present in urine and plasma was dimethylarsinic acid. Sixty percent of the dose was excreted via urine and 6% with feces during the first day. In plasma arsenic was present mainly in a diffusible form, showing a very poor binding affinity to plasma proteins. Chromatographic separations and membrane ultrafiltrations showed that in liver and kidney cytosols, arsenic was significantly associated to proteins. The diffusible fraction disappeared within 48 h. The fraction of arsenic bound to proteins was suggested to be inorganic arsenic whereas the methylation process was closely related to the elimination and the detoxification of inorganic arsenic.