Studies on paraquat-induced oxidative stress in rat liver.

Oxidative injury of liver was studied 20 hr after a single oral administration of 150 mg/kg paraquat (PQ) to rats. PQ exerted no effect on cytosolic superoxide dismutase (SOD) activity but increased mitochondrial SOD activity by 14%. The level of GSH was decreased by 30%, and GSH/GSSG ratio was diminished almost twice. The correlation between the enhancement of mitochondrial SOD activity and the diminution of GSH level by PQ implicates O2- in the liver toxicity of the drug. Mitochondrial aconitase activity was slightly decreased (by 9%) while cytosolic aconitase activity was not affected. The results cast additional light on the responses of both aconitases to oxidative stress.