Reductant substrate for glutathione peroxidase modulates oxidant inhibition of Ca2+ signaling in endothelial cells
Elliott, S.J.; Doan, T.N.; Henschke, P.N.
American Journal of Physiology 268(1 Pt 2): H278-H287
1995
ISSN/ISBN: 0002-9513 PMID: 7840273 Document Number: 449243
Oxidant stress mediated by tert-butyl hydroperoxide (t-BOOH) inhibits agonist-stimulated Ca-2+ entry and internal store Ca-2+ release in cultured endothelial cells. The role of intracellular glutathione in modulating the effects of oxidant stress on Ca-2+ signaling was determined in cells preincubated with buthionine-(S,R)-sulfoximine (BSO), an inhibitor of gamma-glutamylcysteine synthetase, or 1-chloro-2,4-dinitrobenzene (CDNB), a cosubstrate for glutathione-S-transferase. BSO and CDNB decreased endothelial cell glutathione content by 85 and 9 7%, respectively (control glutathione, 21.5 +- 2.3 nmol/mg protein). Each agent accelerated the time-dependent effects of t-BOOH on Ca-2+ signaling in fura 2-loaded cells and potentiated the inhibition of bradykinin-stimulated 45Ca-2+ efflux induced by t-BOOH. These results indicate that decreased availability of reduced glutathione, the primary cosubstrate for glutathione peroxidase, potentiates the effect of hydroperoxide oxidant stress on receptor-operated Ca-2+ entry across the plasmalemma and Ca-2+ release from internal stores. The present findings suggest that intracellular glutathione availability and/or glutathione redox cycle activity are critically important modulators of oxidant inhibition of Ca-2+-dependent signal transduction.