Specific binding of atrial natriuretic peptide to rat mesenteric artery: effect of calcium and 5-guanylylimidodiphosphate.
1. High-dissociation equilibrium constant (20 pmol/1, receptor number 17 fmol/mg) and low-dissociation equilibrium constant (10 nmol/1, receptor number 5 nmol/mg) affinity binding sites for atrial natriuretic peptide have been identified in membrane preparations from rat mesenteric artery. 2. Tracer degradation was corrected for mathematically and binding data were analysed by a non-linear computer technique. 3. Non-atrial natriuretic peptide vasoactive hormones, angiotensin II, vasopressin and bradykinin, did not compete for the high-affinity site. Related peptides with either C- or N-terminal amino acids missing still competed, while peptides without an intact disulphide bridge did not compete. 4. Neither the addition nor the removal of calcium affected the affinity or density of binding sites. Also the non-hydrolysable guanosine triphosphate analogue 5-guanylylimidodiphosphate had no effect on either affinity or number of sites. 5. These results indicate the presence of a specific high-affinity vascular receptor for atrial natriuretic peptide which could interact with the hormone under physiological conditions. The mechanism of binding is uncertain but is unlikely to involve calcium- or guanosine triphosphate-associated regulatory sites.
Lyall
F
F
MRC Blood Pressure Unit, Western Infirmary, Glasgow, Scotland, U.K.
Morton
J J
JJ
D000818:Animals; D009320:Atrial Natriuretic Factor / Q000378:metabolism*; D001665:Binding Sites; D002118:Calcium / Q000494:pharmacology*; D002412:Cations / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000031:analogs & derivatives*; D006165:Guanylyl Imidodiphosphate / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D008638:Mesenteric Arteries / Q000187:drug effects / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects; D051381:Rats; D011919:Rats, Inbred Strains; D017461:Receptors, Atrial Natriuretic Factor; D011956:Receptors, Cell Surface / Q000378:metabolism
D002412:Cations; D008565:Membrane Proteins; D011956:Receptors, Cell Surface; D006165:Guanylyl Imidodiphosphate; D009320:Atrial Natriuretic Factor; D006160:Guanosine Triphosphate; D017461:Receptors, Atrial Natriuretic Factor; D002118:Calcium