BAPTA INDUCES A DECREASE OF INTRACELLULAR FREE CALCIUM AND A TRANSLOCATION AND INACTIVATION OF PROTEIN-KINASE-C IN MACROPHAGES

Addition of BAPTA/AM to liver macrophages lowered the level of [Ca2+]i and induced a translocation and inactivation of protein kinase C. The phorbol ester- and zymosan-induced release of arachidonic acid, prostaglandin E2 and superoxide, the formation of inositol phosphates upon addition of zymosan and the lipopolysaccharide-induced synthesis of TNF-alpha was inhibited by pretreatment of the cells with BAPTA/AM. Simultaneous addition of A 23187 to elevate [Ca]i could not reverse the inhibitory effect of BAPTA. Phagocytosis of zymosan and formation of prostaglandin E2 from exogenously added arachidonic acid or upon addition of A 23187 was not altered by BAPTA/AM. No protein kinase C activity could be measured in homogenates obtained from BAPTA/AM-pretreated cells. These results indicate that the action of BAPTA in eucaryotic cells is not limited to its chelating effect on calcium but that BAPTA leads to a translocation and inactivation of protein kinase C.