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

Endothelin (ET) is a vasoconstrictor peptide released from endothelial cell s 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 wit h either PKC activator or inhibitors and measured the release of prostacycl in (PGI(2)) by radioimmunoassay. ET (10(-9) M) produced a 10-fold increase in PGI(2) release. Pretreatment with 10(-9) M of three different PKC inhibi tors: 1-(5-isoquinolinesulfonyl) piperazine (CL), staurosporine, and 1-(5-i soquinolinesulfonyl-methyl) piperazine (H7) blocked ET induced PGI(2) relea se. ET induced prostacyclin release was also blocked by pretreatment with i nhibitors of either phospholipase A(2) (7,7,dimethyleicosadienoic acid or t rifluoromethyl ketone analogue) (10-9 M) or cyclooxygenase (indomethacin) ( 10(-9)M). We conclude that ET activates PKC which activates phospholipase A (2) which liberates arachidonic acid which increases PGI, production and re lease.