CELLULAR MECHANISM OF NATRIURETIC PEPTIDES-INDUCED INHIBITION OF ENDOTHELIN-1 BIOSYNTHESIS IN RAT ENDOTHELIAL-CELLS

We studied the cellular mechanism by which natriuretic peptides inhibit the synthesis and release of endothelin-1 (ET-1) in cultured rat aortic endothelial cells (EC). Atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) showed dose-dependent and equipotent effects on displacement of [I-125]ANP binding and generation of cGMP production in rat EC, whereas C-type natriuretic peptide and biologically inactive ANP analog had lesser effects. ANP and BNP as well as 8-bromo-cGMP had potent inhibitory effects on immunoreactive ET-1 release, the transient increase in the intracellular Ca2+ concentration, and the formation of inositol 1,4,5-trisphosphate stimulated by thrombin in rat EC. A cGMP-dependent protein kinase inhibitor (KT5823), but not a cAMP-dependent protein kinase inhibitor (KT5720), completely abolished the inhibitory effect of ANP on thrombin-induced immunoreactive Et-1 release. Northern blot analysis using cDNA for rat prepro-ET-1 as a probe showed that ANP and 8-bromo-cGMP, but not C-type natriuretic peptide, inhibited thrombin-induced prepro-ET-1 mRNA expression, whose effect was abolished by KT5823. These data suggest that ANP and BNP inhibit the thrombin-induced synthesis and release of ET-1 in cultured rat aortic EC by blocking phosphoinositide breakdown, possibly via natriuretic peptides type A receptor-mediated cGMP-dependent mechanism.