Transient elevations of cytosolic free calcium retard subsequent apoptosis in neutrophils in vitro

Abstract

Elevation of cytosolic calcium ([Ca2+]i) has been reported to induce apoptosis in a number of cell types. However, in the neutrophil, which undergoes apoptosis constitutively during aging in vitro, activation by inflammatory mediators elevates [Ca2+]i and prolongs lifespan via inhibition of apoptosis. To examine this paradox, we investigated the effects of modulation of [Ca2+]i upon apoptosis of neutrophils in vitro. Calcium ionophores (A23187, ionomycin) retarded apoptosis in neutrophil populations after 20 h (P < 0.001). Conversely, intracellular Ca2+-chelation, using bis-(ο-aminophenoxy)-N,N,N′,N′-tetraacetic acid (BAPTA) acetoxymethyl ester (AM) promoted apoptosis (P < 0.02). W-7 (an inh..