Docosahexaenoic acid and other fatty acids induce a decrease in pHi in Jurkat T-cells.
Fiche publication
Date publication
décembre 2003
Journal
British journal of pharmacology
Auteurs
Membres identifiés du Cancéropôle Est :
Pr KAHN Naim, Dr HICHAMI Aziz, Dr AIRES Virginie
Tous les auteurs :
Aires V, Hichami A, Moutairou K, Khan NA
Lien Pubmed
Résumé
1. Docosahexaenoic acid (DHA) induced rapid (t1/2=33 s) and dose-dependent decreases in pHi in BCECF-loaded human (Jurkat) T-cells. Addition of 5-(N,N-dimethyl)-amiloride, an inhibitor of Na+/H+ exchanger, prolonged DHA-induced acidification as a function of time, indicating that the exchanger is implicated in pHi recovery. 2. Other fatty acids like oleic acid, arachidonic acid, eicosapentaenoic acid, but not palmitic acid, also induced a fall in pHi in these cells. 3. To assess the role of calcium in the DHA-induced acidification, we conducted experiments in Ca2+-free (0% Ca2+) and Ca2+-containing (100% Ca2+) buffer. We observed that there was no difference in the degree of DHA-induced transient acidification in both the experimental conditions, though pHi recovery was faster in 0% Ca2+ medium than that in 100% Ca2+ medium. 4. In the presence of BAPTA, a calcium chelator, a rapid recovery of DHA-induced acidosis was observed. Furthermore, addition of CaCl2 into 0% Ca2+ medium curtailed DHA-evoked rapid pHi recovery. In 0% Ca2+ medium, containing BAPTA, DHA did not evoke increases in [Ca2+]i, though this fatty acid still induced a rapid acidification in these cells. These observations suggest that calcium is implicated in the long-lasting DHA-induced acidosis. 5. DHA-induced rapid acidification may be due to its deprotonation in the plasma membrane (flip-flop model), as suggested by the following observations: (1) DHA with a -COOH group induced intracellular acidification, but this fatty acid with a -COOCH3 group failed to do so, and (2) DHA, but not propionic acid, -induced acidification was completely reversed by addition of fatty acid-free bovine serum albumin in these cells. 6. These results suggest that DHA induces acidosis via deprotonation and Ca2+ mobilization in human T-cells.
Mots clés
Docosahexaenoic Acids, pharmacology, Dose-Response Relationship, Drug, Fatty Acids, Unsaturated, pharmacology, Fluoresceins, Humans, Hydrogen-Ion Concentration, drug effects, Jurkat Cells, Microscopy, Confocal
Référence
Br. J. Pharmacol.. 2003 Dec;140(7):1217-26