The effects of low concentrations of extracellular ATP on cytosolic Ca2+, membrane potential, and transcription of IL-6 were studied in monocyte-derived human macrophages. During inflammation or infection many cells secrete ATP. Application of 10 µM ATP induces oscillations in cytosolic Ca2+ with a frequenzy of 12 min-1 and oscillations in membrane potential. Purinreceptors of macrophages were classified and also potassiumchannels could be identified which take part in the oscillations. The production of IL-6 is 20 times higher during the application of ATP. This findings suggest that ATP is a danger signal for innate immune system.
