Cytosolic calcium ion and arachidonic acid release and metabolism in macrophages.
The aim of the present work was to elucidate the role of cytosolic calcium ions, [Ca2+]i, in the control of arachidonic acid release and metabolism. [Ca2+]i was measured in resident peritoneal rat macrophages loaded with Fura2, and compared with the release of leukotriene B4(LTB4) and prostaglandin l2 (PGL2, assayed through its hydrolysis product 6-keto-PGF1 alpha). The calcium ionophore A 23187 stimulated both an increase in [Ca2+]i and the release of LTB4 and 6-keto-PGF1 alpha. On the contrary, zymosan and opsonized zymosan, while stimulating eicosanoid release to an extent only slightly lower than A 23187, did not affect [Ca2+]i. Lipopolysaccharide stimulated 6-keto-PGF1 alpha, but not LTB4, release, without affecting [Ca2+]i. In parallel experiments, macrophages were prelabelled with [3H]arachidonic acid and the release of total 3H-products was assayed and taken as an index of phospholipase activity. A 23187, zymosan and opsonized zymosan increased the release of 3H-products in the presence of Ca2+. When extracellular Ca2+ was removed, the ionophore-induced 3H-products release was greatly blunted, while the release induced by zymosan was actually augmented. Our data indicate that a generalized [Ca2+]i increase is not necessary for arachidonic acid release and metabolism in rat peritoneal macrophages.
Letari
O
O
Institute of Pharmacological Sciences, University of Milan, Italy.
Malgaroli
A
A
Morgan
D W
DW
Welton
A F
AF
Nicosia
S
S
D000818:Animals; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000378:metabolism*; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism*; D004537:Eicosanoic Acids / Q000378:metabolism; D011464:Epoprostenol / Q000378:metabolism; D016257:Fura-2; D066298:In Vitro Techniques; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D007975:Leukotriene B4 / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology; D008264:Macrophages / Q000378:metabolism*; D008297:Male; D008832:Microchemistry; D010587:Phagocytosis / Q000187:drug effects; D010741:Phospholipases A / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013050:Spectrometry, Fluorescence; D015054:Zymosan / Q000494:pharmacology
D001095:Arachidonic Acids; D004537:Eicosanoic Acids; D008070:Lipopolysaccharides; D007975:Leukotriene B4; D016718:Arachidonic Acid; D000001:Calcimycin; D015054:Zymosan; D011464:Epoprostenol; D007770:L-Lactate Dehydrogenase; D010741:Phospholipases A; D002118:Calcium; D016257:Fura-2