Release of the membrane-calcium and its relation to the superoxide formation by polymorphonuclear leukocytes

Abstract

The relationship between the intracellular translocation of calcium from the storage pool and the oxidative metabolism was studied. An intracellular calcium-antagonist, TMB-8, inhibited the release of superoxide induced by a calcium ionophore A23187 and the inhibition was relieved by the addition of calcium ions. The release induced by cytochalasin D or by the ingestion of bacteria was similarly inhibited by TMB-8. The mobilization of intracellular divalent cations of leukocytes was monitored by a fluorescent probe, CTC. When the CTC-loaded cells were stimulated with cytochalasin D or E. coli, a fluorescence change ascribable to the release of calcium from the intracellular hydrophobic environment was observed. The dose-response curve of the fluorescence change and that of the superoxide release of th cells were very similar. TMB-8 inhibited both metabolic and fluorescence changes in parallel. The results support the hypothesis that an intracellular translocation of calcium is stimulated the oxidative metabolism of leukocytes.