The stimulatory effects of carbon tetrachloride on peroxidative reactions in rat liver fractions in vitro. Inhibitory effects of free-radical scavengers and other agents.

1. The effects of a number of free-radical scavengers and other agents on the stimulation of malonaldehyde production due to low concentrations of carbon tetrachloride have been studied in rat liver microsome suspensions. 2. Promethazine, propyl gallate and NN'-diphenyl-p-phenylenediamine were extremely active in inhibiting the stimulation of malonaldehyde production due to carbon tetrachloride; inhibitory effects were demonstrable with these agents at 0.1mum. 3. Low concentrations (1-100nm) of vitamin E-polyethylene glycol 1000-succinate increased the stimulation of malonaldehyde production due to carbon tetrachloride, but higher concentrations of the vitamin E preparation decreased both the stimulation due to carbon tetrachloride and the endogenous peroxidation that occurs in the absence of carbon tetrachloride. 4. Other agents tested that were effective in the range 1-20mum in decreasing the stimulation of malonaldehyde production due to carbon tetrachloride were inosine, desferrioxamine and EDTA. Agents tested that were not effective, except at very high concentrations (100mum or greater), were Nupercaine, Cetab and sodium phenobarbitone. 5. The results are discussed in terms of the mechanisms responsible for the observed inhibitions of malonaldehyde production, and of the relevance of the in vitro system to the liver damage produced by carbon tetrachloride in vivo.