Activation and inactivation of the volume-sensitive taurine leak pathway in NIH3T3 fibroblasts and Ehrlich Lettre ascites cells.

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Abstract

Hypotonic exposure provokes the mobilization of arachidonic acid, production of ROS, and a transient increase in taurine release in Ehrlich Lettre cells. The taurine release is potentiated by H(2)O(2) and the tyrosine phosphatase inhibitor vanadate and reduced by the phospholipase A(2) (PLA(2)) inhibitors bromoenol lactone (BEL) and manoalide, the 5-lipoxygenase (5-LO) inhibitor ETH-615139, the NADPH oxidase inhibitor diphenyl iodonium (DPI), and antioxidants. Thus, swelling-induced taurine efflux in Ehrlich Lettre cells involves Ca(2+)-independent (iPLA(2))/secretory PLA(2) (sPLA(2)) plus 5-LO activity and modulation by ROS. Vanadate and H(2)O(2) stimulate arachidonic acid mobilization and vanadate potentiates ROS production in Ehrlich Lettre cells and NIH3T3 fibroblasts under hypotonic conditions. However, vanadate-induced potentiation of the volume-sensitive taurine efflux is, in both cell types, impaired in the presence of BEL and DPI and following restoration of the cell volume. Thus, potentiation of the volume-sensitive taurine efflux pathway following inhibition of tyrosine phosphatase activity reflects increased arachidonic acid mobilization and ROS production for downstream signaling. Vanadate delays the inactivation of volume-sensitive taurine efflux in NIH3T3 cells, and this delay is impaired in the presence of DPI. Vanadate has no effect on the inactivation of swelling-induced taurine efflux in Ehrlich Lettre cells. It is suggested that increased tyrosine phosphorylation of regulatory components of NADPH oxidase leads to increased ROS production and a subsequent delay in inactivation of the volume-sensitive taurine efflux pathway and that NADPH oxidase or antioxidative capacity differ between NIH3T3 and Ehrlich Lettre cells.
Original languageEnglish
JournalAmerican Journal of Physiology: Cell Physiology
Volume293
Issue number1
Pages (from-to)C390-400
ISSN0363-6143
DOIs
Publication statusPublished - 2007

Bibliographical note

Keywords: Animals; Antioxidants; Arachidonate 5-Lipoxygenase; Arachidonic Acid; Carcinoma, Ehrlich Tumor; Cell Line, Tumor; Cell Size; Dose-Response Relationship, Drug; Enzyme Inhibitors; Fibroblasts; Hydrogen Peroxide; Hypotonic Solutions; Lipoxygenase Inhibitors; Mice; NADPH Oxidase; NIH 3T3 Cells; Naphthalenes; Onium Compounds; Phospholipases A; Protein Tyrosine Phosphatases; Pyrones; Reactive Oxygen Species; Signal Transduction; Sodium Chloride; Taurine; Terpenes; Time Factors; Vanadates

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