Studies on the mechanism of acetonitrile toxicity 1

Male ICR mice were given a tracer dose of 2-14C-acetonitrile intravenously (60 μ mol/kg or 684 μCi/kg, spec. act. 11.4 mCi/mmol). At various time intervals (5 min., 0.5, 1, 4, 8, 24 and 48 hr) after treatment, mice were anaesthetized and frozen by immersion in a dry ice/hexane mixture, or they were dissected for collection of organs and tissues. Frozen mice were processed for whole body autoradiography, which allows the detection of non-volatile metabolites of acetonitrile at their sites of accumulation. Covalent binding of acetonitrile metabolites in tissues was determined using trichloroacetic acid followed by ethanol/ether extraction techniques. Whole body autoradiography revealed heavy localization of acetonitrile metabolites in the gastrointestinal tissues and bile. At 5 min., the highest levels of radioactivity occurred in the liver and kidney; levels declined over time. At 24 and 48 hr, acetonitrile derived radioactivity were detected in the gastrointestine, thymus, liver and male reproductive organs. Covalent binding studies at 24 and 48 hr after treatment indicated that 40-50% of the total radioactivity present in the liver was bound to the macromolecular fractions of the tissues. The radioactivity contents of other organs were, in large part (40-50% of total), present in the lipid fraction of the tissue. Our studies suggest that the irreversible association with tissus of radioactivity derived from 2-14C-acetonitrile is due to the metabolic activation of acetonitrile and the covalent interaction of reactive metabolite(s) with lipid and macromolecular fractions of the cell. (BN)