RESUMO
The effects of zinc on the production of active oxygen species were investigated in rat neutrophils by chemiluminescence and spectrophotometric assays. The luminol-dependent chemiluminescence in unstimulated neutrophils showed a single peak. Zinc at concentrations lower than 0.1 mM augmented the intensity of chemiluminescence and showed a bimodal pattern, the first peak of which was inhibited by superoxide dismutase and catalase, while the second peak disappeared in the presence of catalase, but was unaffected by superoxide dismutase. At the same concentrations of zinc, O2- and H2O2 production increased, but secretion and activity of myeloperoxidase were not affected. Zinc at 0.1 mM enhanced the second peak of luminol-dependent chemiluminescence, and concomitantly O2- and H2O2 production of neutrophils stimulated with formyl-methionyl-leucyl-phenylalanine. Homogenized neutrophils showed a bimodal pattern on induction by zinc, the second peak of which was inhibited slightly by catalase and completely by sodium azide, but was not inhibited by superoxide dismutase. Zinc-induced O2- production was inhibited by pertussis toxin, but was not significantly inhibited by a protein kinase C inhibitor, 1-(5-isoquinolinesulfonyl)-2-methylpiperazine dihydrochloride (H-7), or a calmodulin antagonist, N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7). These results suggest that zinc can augment luminol-dependent chemiluminescence by increasing O2- production through the classical signal transduction pathway, and by increasing H2O2 not via O2-.
Assuntos
Neutrófilos/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Zinco/farmacologia , Animais , Peróxido de Hidrogênio/metabolismo , Técnicas In Vitro , Medições Luminescentes , Masculino , Neutrófilos/metabolismo , Peroxidase/efeitos dos fármacos , Ratos , Ratos Wistar , Superóxidos/metabolismoRESUMO
The effects of zinc hydroxide on the respiratory burst and phagocytosis by rat neutrophils were examined. Zinc hydroxide induced an increase in oxygen consumption and O2- production. Electronmicroscopy showed that neutrophils engulfed zinc hydroxide particles by phagocytosis. Pertussis toxin (0.25, 0.5, 1.0 micrograms/ml) and EGTA (1, 2, 5 mM) inhibited zinc hydroxide-induced O2- production in a dose-dependent manner. The inhibitors of protein kinase C, 1-(5-isoquinolinesulfonyl)-2-methyl-piperazine and N-[2-(methylamino)ethyl]-5-isoquinolinesulfonamide inhibited zinc hydroxide-induced O2- production with IC50 values ranging between 10 microM and 25 microM. The inhibitory study using an inhibitor of myosin light chain kinase, 1-(5-iodo-naphthalene-1-sulfonyl)-1H-hexahydro-1,4-diazepine, showed IC50 values ranging from 5 microM to 10 microM. These findings indicate that zinc hydroxide induces respiratory burst and phagocytosis by rat neutrophils.
Assuntos
Hidróxidos/farmacologia , Neutrófilos/efeitos dos fármacos , Explosão Respiratória/efeitos dos fármacos , Compostos de Zinco/farmacologia , Animais , Técnicas In Vitro , Microscopia Eletrônica , Neutrófilos/patologia , Consumo de Oxigênio/efeitos dos fármacos , Fagocitose/efeitos dos fármacos , Ratos , Superóxidos/análiseRESUMO
The effect of zinc hydroxide on superoxide (O2-) production by rat alveolar macrophages was determined by chemiluminescence and by cytochrome c reduction. Zinc ions had no effect on the chemiluminescence of unstimulated alveolar macrophages. By contrast, zinc hydroxide (ZnOH2), a neutralized form of zinc ions, increased the chemiluminescence level and O2- release. Increased O2- release was inhibited by pertussis toxin, isoquinoline sulfonamide and pretreatment with EGTA. These findings indicate that zinc hydroxide formation from zinc compounds can stimulate the O2- production by alveolar macrophages by receptor-mediated and Ca(2+)-dependent process.
Assuntos
Hidróxidos/farmacologia , Macrófagos Alveolares/metabolismo , Superóxidos/metabolismo , Compostos de Zinco , Zinco/farmacologia , Animais , Catalase/farmacologia , Grupo dos Citocromos c/metabolismo , Técnicas In Vitro , Cinética , Medições Luminescentes , Macrófagos Alveolares/efeitos dos fármacos , Oxirredução , Ratos , Ratos Endogâmicos , Sulfatos/farmacologia , Superóxido Dismutase/farmacologia , Sulfato de ZincoRESUMO
The immunohistochemical localization of copper, zinc-superoxide dismutase (Cu,Zn-SOD) in human gastric mucosa and gastric cancer was studied using a monoclonal antibody. In gastric mucosa, parietal cells, pyloric glandular cells and foci of intestinal metaplasia showed positive staining in the cytoplasm and/or nucleus. The wide distribution of Cu, Zn-SOD in the gastric mucosa suggests cell function may be vulnerable to active oxygen species. In gastric cancer, 34 of 70 cases showed a positive reaction for Cu, Zn-SOD. There was a relationship between the grade of Cu,Zn-SOD immunoreactivity and the histological type of gastric cancer, well-differentiated types of gastric cancer being more frequently positive. The positive cases of poorly-differentiated adenocarcinoma were characterized by a pattern of diffusely infiltrative invasion. These results suggest that some types of gastric cancer are resistant to active oxygen species.
