mercaptopurine and 6-hydroxy-2-5-7-8-tetramethylchroman-2-carboxylic-acid

To study effects of pharmacologic concentrations of azathioprine and 6-mercaptopurine (6-MP) on rat hepatocytes.. Hepatocytes cultured on matrigel were incubated with azathioprine or 6-MP; effects of putative protective agents were studied. Viability (LDH leakage), reduced (GSH) and oxidized glutathione (GSSG), mitochondrial (mt) GSH, ATP and ultrastructural changes were determined.. Azathioprine and 6-MP (0.5-5 micromol/l) reduced viability 5-34% at day 1 and 42-92% by day 4. Allopurinol (20 microM) (xanthine oxidase inhibitor) and 2 mM Trolox (vitamin E analog) together provided near complete protection. During culture with azathioprine, GSSG increased before cell death and there was a disproportionate reduction of mtGSH and ATP, together with ultrastructural abnormalities in mitochondria. All changes were prevented by allopurinol and trolox. Discontinuation of 1 micromol/l azathioprine restored ATP levels and arrested cell injury, while culture in glucose-enriched media augmented ATP levels and ameliorated cell death.. Clinically relevant concentrations of azathioprine and 6-MP are toxic to rat hepatocyte cultures by a mechanism that involves oxidative stress, mitochondrial injury and ATP depletion. This can lead to irreversible de-energization and cell death by oncosis (necrosis).

Topics: Adenosine Triphosphate; Allopurinol; Animals; Antioxidants; Azathioprine; Cell Differentiation; Cell Survival; Cells, Cultured; Chromans; Enzyme Inhibitors; Glutathione; Glutathione Disulfide; Hepatocytes; Male; Mercaptopurine; Microscopy, Electron; Mitochondria, Liver; Necrosis; Oxidative Stress; Rats; Rats, Wistar; Time Factors; Xanthine Oxidase