The endotoxin stimulated immunoreactive PGI_2, PGF_(2?), PGE_2 and TXA_2 synthesis by mice resident peritoneal macrophages and bovine aorta endothelial cells. The stimulating effect depends on dose and time. The endotoxin also stimulated the release of [~3H] PGI_2 and [~3H] arachidonic acid from [~3H] araehidonic acid prelabelled endothelial cells. The endotoxin-stimulated prostaglandin production was inhibited by polymyxin B, cycloheximide and the antiinflammatory steroid, dexamethasone. Endotoxin might stimulate arachidonic acid metabolism by regulating liberation of esterified arachidonic acid from cellular lipids.

Daphnetin, isolated from Daphne koreane Nakai, has been reported to dilate blood vesse ls, inhibit thrombosis and have antiinflammatory effect. In this study, type Ⅰ and type Ⅱ protcin kinase A partially purified from rat skeletal muscle and protein kinase C from rat brain were incubated with varying concentrations of daphnetin. Type Ⅱ protein kinase A was siguificantly inhibited by daphnetin at the concentration of 0.0056?mol/L, while type Ⅰ protein kinase A and protein kinasc C were inhibitcd at the concentrations of 5.6?mol／L and 56 ?mol/L, respectively. The results indicated that daphnetin might be used as a specific inhibitor of type Ⅱ protein kinase A