HS-142-1, a novel nonpeptide atrial natriuretic peptide (ANP) antagonist, blocks ANP-induced renal responses through a specific interaction with guanylyl cyclase-linked receptors.

HS-142-1, a novel microbial product, blocked 125I-labeled rat atrial natriuretic peptide (rANP) (= ANF(99-126)) binding to bovine adrenocortical membranes, where guanylyl cyclase-containing receptors are predominantly expressed. However, HS-142-1 only slightly inhibited 125I]rANP binding to bovine lung membranes where only a small portion of binding sites are coupled to guanylyl cyclase. Further, HS-142-1 only recognized the 135 kDa ANP receptor, which is considered to be the guanylyl cyclase-containing receptor based on the results obtained in affinity cross-linking studies with bovine adrenocortical and lung membranes. Under identical conditions, Atriopeptin I selectively recognized guanylyl cyclase-free receptors both in binding and affinity cross-linking experiments. When injected intravenously (1 mg/kg) to anesthetized rats, HS-142-1 abolished ANP-induced diuresis and natriuresis. These results suggest that HS-142-1 works in vivo through a specific interaction with the ANP functional receptor, and that HS-142-1 will be a powerful tool for understanding the physiological roles of ANP in distinction from its pharmacological effects.