Extracellular ATP induces spikes in cytosolic free Ca2+ but not in NADH oxidase activity in neutrophils

Jens Christian Brasen, Lars Folke Olsen, Maurice B. Hallett

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In order to establish whether non-mitochondrial oxidase activity in human neutrophils is tightly related to cytosolic Ca2+ concentration, we simultaneously measured Ca2+ oscillations induced by ATP and oxidant production in single adherent neutrophils using confocal microscopy. ATP induced fast damped Ca2+ spikes with a period of 15 s and slower irregular spikes with a period greater than 50 s. Spikes in Ca2+ occurred in the absence of Ca2+ influx, but the amplitude was damped by inhibition of Ca2+ influx. Using the oxidation of hydroethidine as a cytosolic marker of oxidant production, we show that the generation of reactive oxygen species by neutrophils adherent to glass was accelerated by ATP. The step-up in NADPH oxidase activity followed the first elevation of cytosolic Ca2+ but, despite subsequent spikes in Ca2+ concentration, no oscillations in oxidase activity could be detected. ATP induced spikes in Ca2+ in a very reproducible way and we propose that the Ca2+ signal is an on-switch for oxidase activity, but the activity is apparently not directly correlated with spiking activity in cytosolic Ca2+.
TidsskriftBBA Molecular Cell Research
Udgave nummer8
Sider (fra-til)1446-1452
StatusUdgivet - 2011