title: Cyclic AMP and the regulation of prostaglandin production by macrophages.
abstract: The ionophore A23187 (6.7 microM) increased the rates of formation of prostaglandins and cyclic AMP in suspensions of thioglycollate-elicited rat peritoneal macrophages. Both effects were inhibited by the calmodulin blocker trifluoperazine (50 microM) and the calcium channel blocker verapamil (500 microM). Inhibitors of phospholipase A2 and cyclo-oxygenase also blocked both actions of A23187. The stimulated prostaglandin formation was markedly reduced when the cells were preincubated with 8-bromo-cyclic AMP (1mM), dibutyryl cyclic AMP (1mM) or cholera toxin (500ng/ml). Addition of exogenous arachidonic acid (30 microM) alleviated this inhibition. We propose that the effect of A23187 on macrophages includes a 'self-limiting' mechanism whereby newly-synthesized prostaglandins can inhibit, via cyclic AMP, a step(s) prior to the transformation of arachidonic acid and thus modulate their own production.
mesh_terms: D015124:8-Bromo Cyclic Adenosine Monophosphate; D000818:Animals; D001241:Aspirin / Q000494:pharmacology; D003994:Bucladesine / Q000494:pharmacology; D000001:Calcimycin / Q000494:pharmacology; D002772:Cholera Toxin / Q000494:pharmacology; D000242:Cyclic AMP / Q000031:analogs & derivatives / Q000378:metabolism* / Q000494:pharmacology; D007213:Indomethacin / Q000494:pharmacology; D007700:Kinetics; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism*; D011453:Prostaglandins / Q000096:biosynthesis*; D051381:Rats; D014700:Verapamil / Q000494:pharmacology
chemical_list: D011453:Prostaglandins; D015124:8-Bromo Cyclic Adenosine Monophosphate; D000001:Calcimycin; D003994:Bucladesine; D002772:Cholera Toxin; D014700:Verapamil; D000242:Cyclic AMP; D001241:Aspirin; D007213:Indomethacin