PROTEIN-KINASE-C INVOLVED IN ZYMOSAN-INDUCED RELEASE OF ARACHIDONIC-ACID AND SUPEROXIDE BUT NOT IN CALCIUM IONOPHORE-ELICITED ARACHIDONIC-ACID RELEASE OR FORMATION OF PROSTAGLANDIN-E2 FROM ADDED ARACHIDONATE

Zymosan and phorbol ester induced in liver macrophages the release of arachidonic acid, prostaglandin E2, and superoxide; the calcium ionophore A23187 elicited a release of arachidonic acid and prostaglandin E2 but not of superoxide, and exogenously added arachidonic acid led to the formation of prostaglandin E2 only. The zymosan- and phorbol-ester-induced release of arachidonic acid, prostaglandin E2, and superoxide was dose-dependently inhibited by staurosporine and K252a, two inhibitors of protein kinase C, and by pretreatment of the cells with phorbol ester which desensitized protein kinase C. The release of arachidonic acid or prostaglandin E2 following the addition of A23187 or arachidonic acid was not affected by these treatments. Zymosan and phorbol ester but not A23187 or arachidonic acid induced a translocation of protein kinase C from the cytosol to membranes in intact cells. These results demonstrate an involvement of protein kinase C in the zymosan- and phorbol-ester-induced release of arachidonic acid, prostaglandin E2, and superoxide; the release of arachidonic acid and prostaglandin E2 elicited by A23187 and the formation of prostaglandin E2 from exogenously added arachidonic acid, however, is independent of an activation of protein kinase C.