Release of the Membrane-Calcium and Its Relation to the Superoxide Formation by Polymorphonuclear Leukocytes

Abstract

Polymorphonuclear leukocytes produce active oxygens such as superoxide anions and hydrogen peroxide during phagocytosis or by treatment with reagents for example cytochalasin D(Nakagawara et al., 1976), digitonin(Cohen and Chovaniec, 1978) and a calcium ionophore A23187(Romeo et al., 1975). The role of calcium in the activation of the oxidative metabolism has been discussed, based on the observations that the enhancement of the oxygen consumption was induced by the calcium ionophore(Romeo et al. 1975) and the superoxide release by digitonin was inhibited by EGTA(Cohen and Chovaniec, 1978). Supposing that cytoplasmic calcium ions function as a second messenger to regulate the metabolism, we should consider the possibility of an intracellular translocation of the ions between an intracellular storage pool and cytosol as well as the flux of calcium ions through plasma membrane. We show in this report the intracellular mobilization of calcium ions from storage pool and its relation to the oxidative metabolism of leukocytes by using an intracellular calcium antagonist, 8-(N,N-diethylamino)-octyl-3,4,5-trimethoxybenzoate(TMB-8) and a fluorescent probe for divalent cations, chlortetracycline(CTC).