1. 2,4-Dinitrophenol (0.1mm) increases by 100–160% the rate of ethanol metabolism by rat liver slices incubated in a medium saturated with a gas mixture containing O2+CO2+N2 (18:5:77). Similar effects are produced by relatively low concentrations of arsenate (10mm). At higher concentrations (37.5 and 50mm) arsenate inhibits the rate of ethanol metabolism. 2. When liver slices are incubated under an atmosphere containing O2+CO2 (95:5) the metabolism of ethanol increases by about 100% over that obtained with O2+CO2+N2 (18:5:77). However, under these conditions the activating effect of dinitrophenol is no longer observed. 3. Chronic administration of ethanol to rats for 3–4 weeks, in doses from 3 to 8g/kg per day, increases by 70–90% the ability of the liver to metabolize ethanol. In the liver slices of these rats, although an O2+CO2+N2 (18:5:77) mixture was used, dinitrophenol does not further increase the metabolism of ethanol. If the chronic administration of ethanol is discontinued for two weeks, the rate of ethanol metabolism is lowered to control values and the activating effect of dinitrophenol is recovered. 4. No change in alcohol dehydrogenase activity was found in the liver of the rats in which the metabolism of ethanol had been increased as a result of the chronic ethanol treatment; a 40% increase in the activity of succinate dehydrogenase was observed.
