title: Naproxen affects Ca(2+) fluxes in mitochondria, microsomes and plasma membrane vesicles.
abstract: There is substantial evidence that nonsteroidal anti-inflammatory drugs (NSAIDs) affect cellular processes regulated by Ca(2+) ions, including the metabolic responses of the liver to Ca(2+)-dependent hormones. The aim of the present study was to determine whether the effects of naproxen are mediated by a direct action on cellular Ca(2+) fluxes. The effects of naproxen on 45Ca(2+) fluxes in mitochondria, microsomes and inside-out plasma membrane vesicles were examined. Naproxen strongly impaired the mitochondrial capacity to retain 45Ca(2+) and inhibited also ATP-dependent 45Ca(2+) uptake by microsomes. Naproxen did not modify 45Ca(2+) uptake by inside-out plasma membrane vesicles, but it inhibited the hexokinase/glucose-induced Ca(2+) efflux from preloaded vesicles. Additional assays performed in isolated mitochondria revealed that naproxen causes mitochondrial uncoupling and swelling in the presence of Ca(2+) ions. These effects were prevented by EGTA, ruthenium red and cyclosporin A, indicating that naproxen acts synergistically with Ca(2+) ions by promoting the mitochondrial permeability transition. The experimental results suggest that naproxen may impair the metabolic responses to Ca(2+)-dependent hormones acting by at least two mechanisms: (1) by interfering with the supply of external Ca(2+) through a direct action on the plasma membrane Ca(2+) influx, and (2) by affecting the refilling of the agonist-sensitive internal stores, including endoplasmic reticulum and mitochondria.
authors.affiliation: Laboratory of Biological Oxidations, Department of Biochemistry, University of Maringá, Avenue Colombo 5790, 87020900 Maringá, Brazil.
authors.forename: Clairce Luzia
authors.initials: CL
authors.lastname: Salgueiro-Pagadigorria
authors.forename: Ana Maria
authors.initials: AM
authors.lastname: Kelmer-Bracht
authors.forename: Adelar
authors.initials: A
authors.lastname: Bracht
authors.forename: Emy L
authors.initials: EL
authors.lastname: Ishii-Iwamoto
mesh_terms: D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D002462:Cell Membrane / Q000187:drug effects* / Q000378:metabolism; D002614:Chelating Agents / Q000494:pharmacology; D016572:Cyclosporine / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004533:Egtazic Acid / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007700:Kinetics; D008297:Male; D008861:Microsomes / Q000187:drug effects* / Q000378:metabolism; D008930:Mitochondria, Liver / Q000187:drug effects* / Q000378:metabolism; D008933:Mitochondrial Swelling / Q000187:drug effects; D009288:Naproxen / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D012430:Ruthenium Red / Q000494:pharmacology; D014475:Uncoupling Agents / Q000494:pharmacology
chemical_list: D002614:Chelating Agents; D004791:Enzyme Inhibitors; D014475:Uncoupling Agents; D012430:Ruthenium Red; D004533:Egtazic Acid; D009288:Naproxen; D016572:Cyclosporine; D002118:Calcium