Reductant substrate for glutathione peroxidase modulates oxidant inhibition of Ca2+ signaling in endothelial cells.
Oxidant stress mediated by tert-butyl hydroperoxide (t-BOOH) inhibits agonist-stimulated Ca2+ entry and internal store Ca2+ release in cultured endothelial cells. The role of intracellular glutathione in modulating the effects of oxidant stress on Ca2+ 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 97%, respectively (control glutathione, 21.5 +/- 2.3 nmol/mg protein). Each agent accelerated the time-dependent effects of t-BOOH on Ca2+ signaling in fura 2-loaded cells and potentiated the inhibition of bradykinin-stimulated 45Ca2+ 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 Ca2+ entry across the plasmalemma and Ca2+ 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.
Department of Pediatrics, Baylor College of Medicine, Houston, Texas 77030.
S J
SJ
Elliott
T N
TN
Doan
P N
PN
Henschke
D000818:Animals; D001920:Bradykinin / Q000494:pharmacology; D019328:Buthionine Sulfoximine; D002118:Calcium / Q000502:physiology*; D002417:Cattle; D002478:Cells, Cultured; D004137:Dinitrochlorobenzene / Q000494:pharmacology; D004228:Dithionitrobenzoic Acid / Q000494:pharmacology; D004533:Egtazic Acid / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000187:drug effects / Q000201:enzymology / Q000502:physiology*; D005978:Glutathione / Q000378:metabolism; D005979:Glutathione Peroxidase / Q000378:metabolism*; D005982:Glutathione Transferase / Q000378:metabolism; D007700:Kinetics; D008717:Methionine Sulfoximine / Q000031:analogs & derivatives / Q000494:pharmacology; D016877:Oxidants / Q000494:pharmacology*; D010545:Peroxides / Q000494:pharmacology; D011651:Pulmonary Artery; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D013997:Time Factors; D020122:tert-Butylhydroperoxide
D004137:Dinitrochlorobenzene; D016877:Oxidants; D010545:Peroxides; D008717:Methionine Sulfoximine; D019328:Buthionine Sulfoximine; D004533:Egtazic Acid; D020122:tert-Butylhydroperoxide; D004228:Dithionitrobenzoic Acid; D005979:Glutathione Peroxidase; D005982:Glutathione Transferase; D005978:Glutathione; D001920:Bradykinin; D002118:Calcium