HS-142-1, A NOVEL POLYSACCHARIDE OF MICROBIAL ORIGIN, SPECIFICALLY RECOGNIZES GUANYLYL CYCLASE-LINKED ANP RECEPTOR IN RAT GLOMERULI

HS-142-1, a novel polysaccharide, of microbial origin had been characterized as a specific antagonist of guanylyl cyclase-linked atrial natriuretic peptide (ANP) receptors (ANP-GC receptor) in bovine adrenal cortex. The effect of HS-142-1 on ANP receptors of rat glomeruli were examined. HS-142-1 blocked rat ANP (r-ANP)-stimulated cGMP production in a concentration-dependent manner, although it caused only slight inhibition in the specific binding of [I-125]-rANP to the glomeruli where only a small portion of the binding sites are coupled to guanylyl cyclase. HS-142-1 recognized the 135K ANP receptor which is thought to be ANP-GC receptors but did not recognized 60K receptor, guanylyl cyclase-free type from affinity cross-linking studies with glomerular membranes. These results indicate that HS-142-1 is a specific antagonist for the ANP-GC receptor in rat glomeruli, and that it will be a powerful tool for understanding the physiological roles of ANP in renal responses.