Effects of Zinc on Production of Active Oxygen Species by Rat Neutrophils

Abstract

Abstract: The effects of zinc on the production of active oxygen species were investigated in rat neutrophils by chemilumi‐nescence 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, O 2 − and H 2 O 2 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 O 2 − and H 2 O 2 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 O 2 − 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 O 2 − production through the classical signal transduction pathway, and by increasing H 2 O 2 not via O 2 − .