%0 Journal Article %A R Imura %A T Sano %A J Goto %A K Yamada %A Y Matsuda %T 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. %D 1992 %J Molecular Pharmacology %P 982-990 %V 42 %N 6 %X 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. %U https://molpharm.aspetjournals.org/content/molpharm/42/6/982.full.pdf