Mitochondrial Breakage Induced by the Herbicide Paraquat in Cultured Human Lung Cells

Although the intracellular toxic sites of paraquat, a herbicide toxic to human bodies, have remained unclear for a long time, we recently demonstrated paraquat-induced mitochondrial injury in rat lung and liver in vivo</it>. In the present study, cultured human lung cells (A549 adenocarcinoma cell line) which received 0.15 mM paraquat (equivalent to 40 mg/kg i.v.) showed selective mitochondrial breakage at 6–24 hr and died at 36–48 hr. These results suggest that mitochondria are the initial toxic site of paraquat in vitro</it> as well as in vivo</it> in contrast to the previously proposed microsome theory.