Effects of Gramoxone and cooling on the antioxidant enzymes of frog (Rana esculenta).

The effects of paraquat, the active ingredient of Gramoxone, were studied on frogs (Rana esculenta) kept at 4 degrees C or 20 degrees C, to establish its effects on the survival, the antioxidant enzyme system and the lipid peroxidation of the tissues (liver and lung). The lower temperature was found to increase the survival. The activities of the antioxidant enzymes were decreased or not influenced by the LD50 of paraquat at the lower temperature, whereas the LD100 often resulted in a significant enzymatic activity increase. It was an important finding that the lipid peroxidation of the lipid decreased in response to paraquat at 4 degrees C, but increased at 20 degrees C. The lipid peroxidation of the lung increased at both temperatures.