Endothelin-induced prostacyclin production in rat aortic endothelial cells is mediated by protein kinase C

Endothelin (ET) is a vasoconstrictor peptide released from endothelial cells that is known to cause prostaglandin (PG) release. The mechanism remains unclear. To determine whether the protein kinase C (PKC) signaling pathway is stimulated by endothelin, we pretreated rat aortic endothelial cells with either PKC activator or inhibitors and measured the release of prostacyclin (PGI2) by radioimmunoassay. ET (10(-9) M) produced a 10-fold increase in PGI2 release. Pretreatment with 10(-9) M of three different PKC inhibitors: 1-(5-isoquinolinesulfonyl) piperazine (CL), staurosporine, and 1-(5-isoquinolinesulfonyl-methyl) piperazine (H7) blocked ET induced PGI2 release. ET induced prostacyclin release was also blocked by pretreatment with inhibitors of either phospholipase A2 (7,7,dimethyleicosadienoic acid or trifluoromethyl ketone analogue) (10(-9) M) or cyclooxygenase (indomethacin) (10(-9) M). We conclude that ET activates PKC which activates phospholipase A2 which liberates arachidonic acid which increases PGI2 production and release.