Extracellular ATP induces spikes in cytosolic free Ca but not in NADPH oxidase activity in neutrophils |
| |
Authors: | Jens Christian Brasen Lars Folke OlsenMaurice B Hallett |
| |
Institution: | a Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen N, Denmarkb CelCom, Institute of Biochemistry and Molecular Biology, University of Southern Denmark, Denmarkc Neutrophil Signalling Group, School of Medicine, Cardiff University, Heath Park, Cardiff, CF14 4XN, UK |
| |
Abstract: | 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+. |
| |
Keywords: | [Ca2+]cyt cytosolic Ca2+ concentration DAG diacyl glycerol fMLP l-methionyl-l-leucyl-l-phenylalanine" target="_blank">N-Formyl-l-methionyl-l-leucyl-l-phenylalanine HE hydroethidine HRP horseradish peroxidase PKC protein kinase C PB peripheral blood PMA phorbol-12-myristate-13-acetate |
本文献已被 ScienceDirect 等数据库收录! |
|