TY - JOUR T1 - Inhibition by HS-142-1, a novel nonpeptide atrial natriuretic peptide antagonist of microbial origin, of atrial natriuretic peptide-induced relaxation of isolated rabbit aorta through the blockade of guanylyl cyclase-linked receptors. JF - Molecular Pharmacology JO - Mol Pharmacol SP - 982 LP - 990 VL - 42 IS - 6 AU - R Imura AU - T Sano AU - J Goto AU - K Yamada AU - Y Matsuda Y1 - 1992/12/01 UR - http://molpharm.aspetjournals.org/content/42/6/982.abstract N2 - HS-142-1, a specific nonpeptide antagonist for the atrial natriuretic peptide (ANP) receptor, equally blocked rat ANP (rANP)-, porcine brain natriuretic peptide-, or porcine C-type natriuretic peptide-stimulated GMP production in cultured bovine aortic smooth muscle (BASM) and bovine aortic endothelial (BAE) cells in a concentration-dependent fashion, at concentrations of 1-300 micrograms/ml. But, even at 300 micrograms/ml, HS-142-1 only weakly inhibited the specific binding of 125I-rANP to the BASM and BAE cells, where only a small portion of the binding sites are linked to guanylyl cyclase. Further, with BAE cell membranes, HS-142-1 recognized only the 135-kDa ANP receptor, which is thought from 125I-rANP affinity cross-linking studies to be the guanylyl cyclase-linked receptor. HS-142-1 also, if anything, inhibited the labeling of 135-kDa ANP receptors in the affinity cross-linking studies with BASM membranes, suggesting that a major portion of the 135-kDa ANP receptors are HS-142-1 insensitive and only a small portion of the 135-kDa ANP receptors are responsible for the blockade by HS-142-1 of GMP production in BASM cells. At a concentration of 100 micrograms/ml, HS-142-1 reversibly prevented ANP-induced relaxation of the isolated rabbit thoracic aorta induced to contract with 3 x 10(-7) M phenylephrine, but not the relaxation induced by sodium nitroprusside, isoproterenol, or papaverine. These results suggest that HS-142-1 specifically inhibits natriuretic peptide-induced vasorelaxation through the blockade of guanylyl cyclase-linked natriuretic peptide receptors. HS-142-1 thus will be a powerful tool for understanding the physiological roles, in vasculature, of natriuretic peptides, which contribute to the homeostasis of blood pressure and intravascular volume. ER -