title: Relationships between the mitochondrial transmembrane potential, ATP concentration, and cytotoxicity in isolated rat hepatocytes.
abstract: The relationships between mitochondrial transmembrane potential, ATP concentration, and cytotoxicity were evaluated after exposure of isolated rat hepatocytes to different mitochondrial poisons. Both the neurotoxicant 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and its fully oxidized metabolite, the 1-methyl-4-phenylpyridinium (MPP+) ion, caused a concentration- and time-dependent depolarization of mitochondrial membranes which followed ATP depletion and preceded cytotoxicity. The effect of MPTP, but not that of MPP+, was prevented by deprenyl, an inhibitor of MPTP conversion to MPP+ via monoamine oxidase type B. Addition of fructose to the hepatocyte incubations treated with either MPTP or MPP+ counteracted the loss of mitochondrial transmembrane potential. Fructose was also effective in protecting against the mitochondrial membrane depolarization as well as ATP depletion and cytotoxicity induced by antimycin. A, carbonyl cyanide p-trifluoromethoxyphenyl hydrazone, and valinomycin. Data confirm the key role played by MPP(+)-induced mitochondrial damage in MPTP toxicity and indicate that (i) ATP produced via the glycolytic pathway can be utilized by hepatocytes to maintain mitochondrial electrochemical gradient, and (ii) a loss of mitochondrial membrane potential may occur only when supplies of ATP are depleted.
authors.affiliation: Department of Biomedical and Environmental Health Sciences, School of Public Health, University of California, Berkeley 94720.
authors.forename: E Y
authors.initials: EY
authors.lastname: Wu
authors.forename: M T
authors.initials: MT
authors.lastname: Smith
authors.forename: G
authors.initials: G
authors.lastname: Bellomo
authors.forename: D
authors.initials: D
authors.lastname: Di Monte
mesh_terms: D015632:1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine / Q000037:antagonists & inhibitors; D015655:1-Methyl-4-phenylpyridinium / Q000633:toxicity; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D002470:Cell Survival / Q000187:drug effects*; D005456:Fluorescent Dyes; D005632:Fructose / Q000494:pharmacology; D066298:In Vitro Techniques; D007425:Intracellular Membranes / Q000502:physiology*; D008099:Liver / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D020267:MPTP Poisoning; D008297:Male; D008564:Membrane Potentials; D008930:Mitochondria, Liver / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D020112:Rhodamine 123; D012235:Rhodamines; D012642:Selegiline / Q000494:pharmacology
chemical_list: D005456:Fluorescent Dyes; D012235:Rhodamines; D020112:Rhodamine 123; D012642:Selegiline; D005632:Fructose; D000255:Adenosine Triphosphate; D015632:1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine; D015655:1-Methyl-4-phenylpyridinium