Effect of pretreatment with 3-methylcholanthrene and several phenolic antioxidants on glutathione S-transferase activity in various tissues of female Sprague-Dawley rats.

1. Treatment of female Sprague-Dawley rats with 3-methylcholanthrene, butylated hydroxyanisole, ethoxyquin, propyl gallate or methylcholanthrene plus butylated hydroxyanisole was undertaken to determine the effects on glutathione S-transferase activity in liver, small intestine, lung and kidney. 2. A significant increase in hepatic transferase activity was found following all treatments, except after propyl gallate, when 1-chloro-2,4-dinitrobenzene was used as substrate. 3. When 1,2-dichloro-4-nitrobenzene was the substrate, only butylated hydroxyanisole and the combination of butylated hydroxyanisole and methylcholanthrene resulted in a significant increase. 4. In the extra-hepatic tissues using 1-chloro-2,4-dinitrobenzene as a substrate, all treatments caused an increase in transferase activity in the lung; ethoxyquin and combined methylcholanthrene plus butylated hydroxyanisole increased this activity in the kidney, whereas only the combined methylcholanthrene plus butylated hydroxyanisole increased activity in the small intestine. 5. All treatments caused a notable decrease in the composite Km and had varying effects on the composite Vmax of hepatic transferase activity.