Amino acid metabolism in various fractions of rat-brain homogenates with special reference to the effect of ethanol.

1. The increase in brain gamma-aminobutyrate, glutamate and aspartate and the decrease in brain glutamine that occur when ethanol is administered to rats in vivo could be reproduced by incubating brain homogenates from rats pretreated with ethanol. 2. For the demonstration of the effects of pretreatment with ethanol on the metabolism of gamma-aminobutyrate and glutamine, the whole homogenate could be replaced by various supernatant preparations, and even by the soluble protein fraction, which was less active, however. The ;postmitochondrial' sediment could likewise mediate the effects of pretreatment with ethanol. 3. When the brain homogenates from control and ethanol-treated rats were allowed to ;age' at 2 degrees for more than 7 days, the metabolic difference at incubation could no longer be demonstrated. The capacities of the homogenate from the control rats had changed to resemble those of ethanol-treated rats. 4. Data are given on the effects of the incubation time and of the concentration of homogenate.