Involvement of external calcium in the release of arachidonic acid by mouse peritoneal macrophages.

The present investigation was undertaken to study the potential role of extracellular calcium on the release of arachidonic acid from mouse peritoneal macrophages. Both in phorbol ester-treated and in Ca2(+)-depleted cells, a rapid release of arachidonic acid was seen in direct response to added Ca2+. The response was directly dependent on the extracellular Ca2+ concentration, with a Ca2+ threshold of 100 nM. These results support the notion that arachidonic acid release in macrophages is functionally coupled to influx of external calcium.