Molecular and Cellular Biochemistry

, Volume 210, Issue 1, pp 153–158

Flufenamic acid as an inducer of mitochondrial permeability transition

  • Maria C. Jordani
  • Antonio C. Santos
  • Ieda M.R. Prado
  • Sérgio A. Uyemura
  • Carlos Curti
Article

DOI: 10.1023/A:1007185825101

Cite this article as:
Jordani, M.C., Santos, A.C., Prado, I.M. et al. Mol Cell Biochem (2000) 210: 153. doi:10.1023/A:1007185825101

Abstract

To assess the mechanism by which mitochondrial permeability transition (MPT) is induced by the nonpolar carboxylic acids, we investigated the effects of flufenamic acid (3′-trifluoromethyl diphenylamine-2-carboxylic acid, FA) on mitochondrial respiration, electrical transmembrane potential difference (ΔΨ), osmotic swelling, Ca2+ efflux, NAD(P)H oxidation and reactive oxygen species (ROS) generation. Succinate-energized isolated rat liver mitochondria incubated in the absence or presence of 10 μM Ca2+, 5 μM ruthenium red (RR) or 1 μM cyclosporin A (CsA) were used. The dose response-curves for both respiration release and ΔΨ dissipation were nearly linear, presenting an IC50 of approximately 10 μM and reaching saturation within 25-50 μM, indicating that FA causes mitochondrial uncoupling by a protonophoric mechanism. Within this same concentration range FA showed the ability to induce MPT in energized mitochondria incubated with 10 μM Ca2+, followed by ΔΨ dissipation and Ca2+ efflux, and even in deenergized mitochondria incubated with 0.5 mM Ca2+. ADP, Mg2+, trifluoperazine (TFP) and N-ethylmaleimide (NEM) reduced the extent of FA-promoted swelling in energized mitochondria by approximately one half, whereas dithiothreitol (DTT) slightly enhanced it. NAD(P)H oxidation and ROS generation (H2O2 production) by mitochondria were markedly stimulated by FA; these responses were partly prevented by CsA, suggesting that they may be implicated as both a cause and effect of FA-induced MPT. FA incubated with mitochondria under swelling assay conditions caused a decrease of approximately 40% in the content of protein thiol groups reacting with 5,5′-dithiobis(2-nitrobenzoic acid) (DTNB). The present results are consistent with a ROS-intermediated sensitization of MPT by a direct or indirect FA interaction with inner mitochondrial membrane at a site which is in equilibrium with the NAD(P)H pool, namely thiol groups of integral membrane proteins.

nonsteroidal antiinflammatory drugsnonpolar carboxylic acidsflufenamic acidliver mitochondriamitochondrial uncouplingmitochondrial permeability transitionmitochondrial Ca2+ effluxNAD(P)H oxidationreactive oxygen species

Copyright information

© Kluwer Academic Publishers 2000

Authors and Affiliations

  • Maria C. Jordani
    • 1
  • Antonio C. Santos
    • 2
  • Ieda M.R. Prado
    • 1
  • Sérgio A. Uyemura
    • 2
  • Carlos Curti
    • 1
  1. 1.Department of Physics and Chemistry, School of Pharmaceutical SciencesUniversity of São PauloRibeirão Preto, São PauloBrazil
  2. 2.Department of Clinical, Toxicological and Bromatological Analysis, School of Pharmaceutical SciencesUniversity of São PauloRibeirão Preto, São PauloBrazil