title: The critical role of mitochondrial energetic impairment in the toxicity of nimesulide to hepatocytes.
abstract: We described the effects of nimesulide (N-[4-nitro-2-phenoxyphenyl]-methanesulfonamide) and its reduced metabolite in isolated rat hepatocytes. Nimesulide stimulated the succinate-supported state 4 respiration of mitochondria, indicating an uncoupling effect of the drug. Incubation of hepatocytes with nimesulide (0.1-1 mM) elicited a concentration- and time-dependent decrease in cell viability as assessed by lactate dehydrogenase leakage, a decrease of mitochondrial membrane potential as assessed by rhodamine 123 retention, and cell ATP depression. Nimesulide also decreased the levels of NAD(P)H and glutathione in hepatocytes, but the extent of the effects was less pronounced in relation to the energetic parameters; in addition, these effects did not imply the peroxidation of membrane lipids. The decrease in the viability of hepatocytes was prevented by fructose and, to a larger extent, by fructose plus oligomycin; it was stimulated by proadifen, a cytochrome P450 inhibitor. In contrast, the reduced metabolite of nimesulide did not present any of the effects observed for the parent drug. These results indicate that: 1) nimesulide causes injury to the isolated rat liver cells, 2) this effect is mainly mediated by impairment of ATP production by mitochondria due to uncoupling, and 3) on account of the activity of its nitro group, the parent drug by itself is the main factor responsible for its toxicity to the hepatocytes.
authors.affiliation: Departamento de Física e Química, Toxicológicas e Bromatológicas, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, Av. Café s/n, 14040-903 Ribeirão Preto, São Paulo, Brazil.
authors.forename: Fábio E
authors.initials: FE
authors.lastname: Mingatto
authors.forename: Tiago
authors.initials: T
authors.lastname: Rodrigues
authors.forename: Acácio A
authors.initials: AA
authors.lastname: Pigoso
authors.forename: Sérgio A
authors.initials: SA
authors.lastname: Uyemura
authors.forename: Carlos
authors.initials: C
authors.lastname: Curti
authors.forename: Antonio C
authors.initials: AC
authors.lastname: Santos
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000633:toxicity*; D000975:Antioxidants / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D004734:Energy Metabolism / Q000187:drug effects*; D005456:Fluorescent Dyes; D005632:Fructose / Q000494:pharmacology; D005978:Glutathione / Q000378:metabolism; D066298:In Vitro Techniques; D007770:L-Lactate Dehydrogenase / Q000037:antagonists & inhibitors; D015227:Lipid Peroxidation / Q000187:drug effects; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D008930:Mitochondria, Liver / Q000187:drug effects / Q000378:metabolism*; D009249:NADP / Q000378:metabolism; D009840:Oligomycins / Q000494:pharmacology; D010101:Oxygen Consumption / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D013449:Sulfonamides / Q000633:toxicity*
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D000975:Antioxidants; D005456:Fluorescent Dyes; D009840:Oligomycins; D013449:Sulfonamides; D005632:Fructose; D009249:NADP; D000255:Adenosine Triphosphate; D007770:L-Lactate Dehydrogenase; D005978:Glutathione; C012655:nimesulide