Effects of culture duration, cytochrome P-450 inhibition and glutathione depletion on toxicity of diverse xenobiotics.

The toxicity of six compounds was investigated in rat hepatocyte cultures: 3-hr cultures were exposed to toxin between 3 and 24 hr after plating and 24-hr cultures between 24 and 48 hr after plating. The toxicities of sodium dodecyl sulfate (SDS), allyl alcohol and 8-methoxypsoralen (8-MOP) were similar in 3- and 24-hr cultures, whereas precocene II, 1,3-dichloro-2-propanol (DC2P) and coumarin were all less toxic in 24-hr cultures than in 3-hr cultures. Pretreatment of cultures with the cytochrome P-450 inhibitor 1-aminobenzotriazole abolished the toxicities of coumarin and DC2P and decreased the toxicity of precocene II in both 3- and 24-hr cultures. In addition, the toxicity of precocene II appeared to correlate with the activity of the high-affinity form of 7-methoxycoumarin O-demethylase. Pretreatment of cultures with diethyl maleate (DEM) or buthionine sulfoximine (BSO) increased the toxicity of allyl alcohol, precocene II and DC2P, but not SDS. DEM enhanced the toxicity of 8-MOP in 3-hr cultures and BSO enhanced the toxicity of coumarin in 24-hr cultures. It was also demonstrated that the onset of DC2P toxicity was observed earlier in BSO-treated cultures than in DEM-treated cultures. For the compounds tested, culture age seems less important in determining toxicity than choice of glutathione-depleting agent.