Identification of amino sugars.

1. The acute hepatotoxic action of dimethylnitrosamine was investigated with homogenates and mitochondrial preparations from the livers of rats injected with 100 mg./kg. body weight at various times between 8 and 24 hr. before killing. 2. Aerobic oxidation of pyruvate, octanoate, L-malate, citrate, L-glutamate, a-oxoglutarate and ,-hydroxybutyrate progressively decreased after the twelfth hour and was grossly reduced by the twentieth hour. Aerobic oxidation of choline was only slightly reduced. Succinoxidase activity and anaerobic glycolysis were unaffected even when necrosis was extensive. 3. Oxygen uptakes of the diphosphopyridine nucleotide-linked systems could be greatly raised by the addition of diphosphopyridine nucleotide to the mitochondrial incubation medium. No other cofactor tested was effective. 4. Dimethylnitrosamine did not show an effect in vitro on normal rat-liver homogenate. Ethylenediaminetetra-acetic acid did not reverse theinhibition of aerobic oxidation of mitochondrial preparations made 16 hr. after poisoning.