diethyl-maleate and 2-thiomalic-acid

The role of H(2)O(2) and protein thiol oxidation in oxidative stress-induced epithelial paracellular permeability was investigated in Caco-2 cell monolayers. Treatment with a H(2)O(2) generating system (xanthine oxidase + xanthine) or H(2)O(2) (20 microM) increased the paracellular permeability. Xanthine oxidase-induced permeability was potentiated by superoxide dismutase and prevented by catalase. H(2)O(2)-induced permeability was prevented by ferrous sulfate and potentiated by deferoxamine and 1,10-phenanthroline. GSH, N-acetyl-L-cysteine, dithiothreitol, mercaptosuccinate, and diethylmaleate inhibited H(2)O(2)-induced permeability, but it was potentiated by 1,3-bis(2-chloroethyl)-1-nitrosourea. H(2)O(2) reduced cellular GSH and protein thiols and increased GSSG. H(2)O(2)-mediated reduction of GSH-to-GSSG ratio was prevented by ferrous sulfate, GSH, N-acetyl-L-cysteine, diethylmaleate, and mercaptosuccinate and potentiated by 1,10-phenanthroline and 1, 3-bis(2-chloroethyl)-1-nitrosourea. Incubation of soluble fraction of cells with GSSG reduced protein tyrosine phosphatase (PTPase) activity, which was prevented by coincubation with GSH. PTPase activity was also lower in H(2)O(2)-treated cells. This study indicates that H(2)O(2), but not O(2)(-). or.OH, increases paracellular permeability of Caco-2 cell monolayer by a mechanism that involves oxidation of GSH and inhibition of PTPases.

Topics: Acetylcysteine; Antineoplastic Agents, Alkylating; Caco-2 Cells; Carmustine; Catalase; Cell Membrane Permeability; Chelating Agents; Deferoxamine; Free Radical Scavengers; Glutathione; Humans; Hydrogen Peroxide; Intestinal Mucosa; Intestines; Iron; Maleates; Oxidants; Oxidation-Reduction; Phenanthrolines; Protein Tyrosine Phosphatases; Protein-Tyrosine Kinases; Signal Transduction; Sulfhydryl Compounds; Superoxide Dismutase; Thiomalates; Tight Junctions; Vitamin A; Vitamin E

The relative levels of reduced glutathione (GSH) have been measured fluorimetrically in individual eggs and early embryos from two mouse strains, one of which shows developmental arrest in vitro. GSH levels fell by approximately 20-25% at fertilization and by approximately 45% by the late 2-cell and early 4-cell stages. No differences were observed between strains or between embryos cultured in vitro or in vivo. Addition of exogenous H2O2 or diethylmaleate depleted GSH. GSH levels were not affected significantly after inhibition of GSH-peroxidase by mercaptosuccinate nor of catalase by aminotriazole. Mercaptosuccinate did not inhibit development but catalase inhibition caused arrest at the 2-cell stage. Addition of exogenous GSH or thioredoxin did not promote development of 'blocking' embryos through the 2-cell block. It is concluded that early embryos lack a mercaptosuccinate sensitive peroxidase activity for removing H2O2, which may be removed by catalase or the glutathione-S-transferase system. It is suggested that GSH may have a role in detoxifying peroxidated lipids. The results are consistent with a role for reactive oxygen species in the 2-cell block.

Topics: Amitrole; Animals; Blastocyst; Catalase; Dose-Response Relationship, Drug; Fertilization in Vitro; Fluorometry; Glutathione; Glutathione Peroxidase; Hydrogen Peroxide; In Vitro Techniques; Lipid Peroxidation; Maleates; Mice; Thiomalates; Thioredoxins; Time Factors