Mitochondrial alterations induced by aspirin in rat hepatocytes expressing mitochondrially targeted green fluorescent protein (mtGFP)

Mitochondria in primary living hepatocytes were visualized in cells transfected with a chimeric plasmid encoding for the green fluorescent protein (GFP) of Aequorea victoria engineered to be specifically targeted to mitochondria, as described recently (Rizzuto et al. (1995) Curr. Biol. 5, 635–642). The identification of the fluorescent organelles as authentic mitochondria was confirmed by double labeling with rhodamine 123. Acetylsalicylate treatment of hepatocytes induced in mitochondria typical morphological alterations closely analogous to the swelling promoted by acetylsalicylate in isolated mitochondria. Cyclosporin A, which in isolated mitochondria prevents the changes induced by acetylsalicylate, had no protective action but induced per se specific alterations in the morphology of mitochondria. Moreover, exposure of hepatocytes to cyclosporin A followed by acetylsalicylate caused the same mitochondrial changes induced by each of the two compounds separately. The structural alterations caused by acetylsalicylate were constantly associated with a decrease in mitochondrial urea synthesis and cell viability.