Species variations in the sensitivity of the endoplasmic reticulum to the herbicide 1.1.1. trifluoro-N-(2-methyl-4-phenyl sulfonyl phenyl) methane sulfonamide.

1. The effects of the herbicide 1.1.1. trifluoro-N-(2-methyl-4-phenyl sulfonyl phenyl) methane sulfonamide on the drug metabolising enzyme activities in livers of rat, mouse and guinea pig have been compared. 2. In all three animal models, the herbicide increased the activities of both aniline hydroxylase and p-aminopyrine demethylase. The greatest inductive effect was seen in the rat, while the least effect was evident in the guinea pig. 3. In mouse and guinea pig, 1.1.1. trifluoro-N-(2-methyl-4-phenyl sulfonyl phenyl) methane sulfonamide had no effect on the soluble or microsomal epoxide hydratases or the glutathione S-transferases. In the rat, however, the herbicide significantly decreased the microsomal epoxide hydratase activity, as well as the soluble and microsomal glutathione S-transferase activities. 4. These results are discussed in relation to factors responsible for species differences in the response to foreign compounds.