title: Heterogeneous binding sites for alpha-atrial natriuretic peptide in human umbilical cord and placenta.
abstract: The distributions of atrial natriuretic peptide (ANP) clearance receptors in human umbilical cord and placenta were investigated by using des[Gln18,Ser19,Gly20,Leu21,Gly22]ANP-(4-2 3) (C-ANP) as a specific ligand of this receptor to displace bound alpha-125I-labeled ANP. alpha-125I-ANP bound reversibly to umbilical venous and arterial intima and to fetal placental and maternal decidual tissues, with dissociation constants of 1.24 +/- 0.51, 0.58 +/- 0.19, 1.86 +/- 0.51, and 1.07 +/- 0.25 mM, respectively. Binding was reversed by 1 microM unlabeled alpha-ANP but not by unrelated peptides such as gastrin. The 1 microM C-ANP displaced bound alpha-125I-ANP from the intima of umbilical artery but not that of the vein. The specific reversible binding of alpha-125I-ANP to placental decidua but not to fetal placenta was also displaced by 1 microM C-ANP. Therefore high-affinity binding sites for alpha-ANP on the intima of the umbilical artery and on placental decidua differ from those on the umbilical vein and on fetal placental tissue; the binding sites of the intima of the umbilical artery and of the decidua in humans are consistent with clearance receptors for alpha-ANP.
authors.affiliation: Royal Postgraduate Medical School, London, United Kingdom.
authors.forename: S P
authors.initials: SP
authors.lastname: Salas
authors.forename: R F
authors.initials: RF
authors.lastname: Power
authors.forename: A
authors.initials: A
authors.lastname: Singleton
authors.forename: J
authors.initials: J
authors.lastname: Wharton
authors.forename: J M
authors.initials: JM
authors.lastname: Polak
authors.forename: J
authors.initials: J
authors.lastname: Brown
mesh_terms: D000328:Adult; D009320:Atrial Natriuretic Factor / Q000378:metabolism*; D001345:Autoradiography; D001667:Binding, Competitive; D003656:Decidua / Q000378:metabolism; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes; D007700:Kinetics; D010920:Placenta / Q000166:cytology / Q000378:metabolism*; D011247:Pregnancy; D011869:Radioligand Assay; D017461:Receptors, Atrial Natriuretic Factor; D011956:Receptors, Cell Surface / Q000378:metabolism*; D014469:Umbilical Arteries / Q000166:cytology / Q000378:metabolism*; D014470:Umbilical Cord / Q000166:cytology / Q000378:metabolism*; D014471:Umbilical Veins / Q000166:cytology / Q000378:metabolism*
chemical_list: D007457:Iodine Radioisotopes; D011956:Receptors, Cell Surface; D009320:Atrial Natriuretic Factor; D017461:Receptors, Atrial Natriuretic Factor