FMLP-induced arachidonic acid release, phospholipid metabolism, and calcium mobilization in human monocytes. Regulation by cyclic AMP.
Radiolabeled human peripheral blood monocytes released [3H]arachidonic acid upon challenge with the calcium ionophore A23187 (10 microM), or f-Met-Leu-Phe (FMLP, 1 microM). Chromatographic analysis of [3H]arachidonic acid labeled phospholipids showed that stimulation by FMLP reduced the amount of labeled phosphatidylcholine exclusively. Treatment of the monocytes with 10(-3) M dibutyryl cyclic AMP (d-cAMP) or 5 X 10(-4) M isobutylmethylxanthine (IBMX) substantially inhibited [3H]arachidonic acid release (30%) and depletion from labeled phosphatidylcholine (PC) in FMLP--but not calcium ionophore--stimulated cells. Using the fluorescent probe Indo-1, the FMLP-induced cytosolic calcium increase was unaffected by 10(-3) M dibutyryl cyclic AMP. The results suggest that FMLP-stimulated phospholipase activity is regulated by cyclic AMP, but not by depressing receptor-medicated increases in cytoplasmic free calcium.
Godfrey
R W
RW
Department of Experimental Pathology, SmithKline and French Laboratories, Swedeland, Pennsylvania 19406.
Manzi
R M
RM
Jensen
B D
BD
Hoffstein
S T
ST
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000378:metabolism*; D003994:Bucladesine / Q000494:pharmacology; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D002855:Chromatography, Thin Layer; D000242:Cyclic AMP / Q000502:physiology*; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D009000:Monocytes / Q000187:drug effects* / Q000378:metabolism; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology*; D010743:Phospholipids / Q000378:metabolism*
D001095:Arachidonic Acids; D010743:Phospholipids; D016718:Arachidonic Acid; D000001:Calcimycin; D009240:N-Formylmethionine Leucyl-Phenylalanine; D003994:Bucladesine; D000242:Cyclic AMP; D002118:Calcium; D015056:1-Methyl-3-isobutylxanthine