Regulation of arachidonic acid release in mouse peritoneal macrophages. The role of extracellular calcium and protein kinase C.
Primary cultures of [3H]arachidonic acid-prelabeled mouse peritoneal macrophages were stimulated with the physiologic agonists zymosan and Con A. The cells released a large quantity of labeled compounds into the extracellular medium. When the cells were preincubated for 10 min with PMA at concentrations from 10 to 1000 ng/ml, zymosan- and Con A-stimulated compound release was greatly enhanced. PMA also potentiated arachidonic acid release when cells were stimulated with the calcium ionophore A23187. However, under the same conditions, PMA treatment blocked agonist- and ionophore-mediated phosphoinositide hydrolysis in cells prelabeled with [3H]inositol. Thus, PMA treatment appears to have dissociated agonist-induced arachidonic acid liberation (index of phospholipase A2) from phosphoinositide hydrolysis (index of phospholipase C), suggesting that these two coupling processes can occur in a parallel and independent manner in mouse peritoneal macrophages. Furthermore, the ligand-induced arachidonic acid release from PMA-treated macrophages was shown to be directly dependent on the extracellular calcium concentration. Considering that in PMA-pretreated cells, receptor-mediated phosphoinositide breakdown and intracellular calcium mobilization were abolished, our data suggest that the extracellular calcium influx that takes place after receptor-ligand interaction may be a required event for arachidonic acid mobilization in mouse peritoneal macrophages.
Balsinde
J
J
Unidad de Biomembranas, Hospital Universitario de San Carlos, Madrid, Spain.
Fernández
B
B
Diez
E
E
D000818:Animals; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000378:metabolism*; D001202:Ascitic Fluid / Q000166:cytology; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000502:physiology*; D003208:Concanavalin A / Q000494:pharmacology; D007295:Inositol Phosphates / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism*; D051379:Mice; D011493:Protein Kinase C / Q000502:physiology*; D012636:Secretory Rate / Q000187:drug effects; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D015054:Zymosan / Q000494:pharmacology
D001095:Arachidonic Acids; D007295:Inositol Phosphates; D003208:Concanavalin A; D016718:Arachidonic Acid; D000001:Calcimycin; D015054:Zymosan; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium