title: Novel snake venom ligand dendroaspis natriuretic peptide is selective for natriuretic peptide receptor-A in human heart: downregulation of natriuretic peptide receptor-A in heart failure.
abstract: The natriuretic peptides are considered to be cardioprotective; however, their receptors have not been identified in human myocardium using radiolabeled analogs. Dendroaspis natriuretic peptide (DNP) has been recently identified as a new member of this peptide family and is thought to be less susceptible to enzymatic degradation. Therefore, we have developed the novel radiolabeled analog [125I]-DNP and used this to localize high-affinity (K(D)=0.2 nmol/L), saturable, specific binding sites in adult human heart (n=6) and coronary artery (n=8). In competition binding experiments, atrial natriuretic peptide and brain type natriuretic peptide had greater affinity for [125I]-DNP binding sites than C-type natriuretic peptide and the natriuretic peptide receptor (NPR)-C ligand, cANF. This rank order of potency suggested binding of [125I]-DNP was specific to NPR-A. Messenger RNA encoding NPR-A was identified in left ventricle and coronary artery smooth muscle, and expression was confirmed by immunocytochemical studies at the protein level. In addition, fluorescence dual labeling immunocytochemistry localized NPR-A protein to cardiomyocytes, endocardial endothelial cells, and smooth muscle of intramyocardial vessels. Importantly, we demonstrated a significant downregulation in the density of NPR-A in heart and coronary artery of patients with ischemic heart disease that may explain, in part, the attenuated natriuretic peptide response reported in this patient group.
authors.affiliation: Clinical Pharmacology Unit, University of Cambridge, Level 6, Centre for Clinical Investigation, Box 110, Addenbrooke's Hospital, Cambridge CB2 2QQ, UK.
authors.forename: Gurminder
authors.initials: G
authors.lastname: Singh
authors.forename: Rhoda E
authors.initials: RE
authors.lastname: Kuc
authors.forename: Janet J
authors.initials: JJ
authors.lastname: Maguire
authors.forename: Mark
authors.initials: M
authors.lastname: Fidock
authors.forename: Anthony P
authors.initials: AP
authors.lastname: Davenport
mesh_terms: D000328:Adult; D001665:Binding Sites; D003331:Coronary Vessels / Q000737:chemistry / Q000378:metabolism; D015536:Down-Regulation / Q000235:genetics; D004546:Elapid Venoms / Q000493:pharmacokinetics*; D005260:Female; D006162:Guanylate Cyclase / Q000235:genetics / Q000378:metabolism*; D006333:Heart Failure; D006352:Heart Ventricles / Q000737:chemistry; D006801:Humans; D007150:Immunohistochemistry; D036341:Intercellular Signaling Peptides and Proteins; D007457:Iodine Radioisotopes / Q000493:pharmacokinetics; D008024:Ligands; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000378:metabolism*; D010455:Peptides / Q000493:pharmacokinetics*; D011485:Protein Binding; D012333:RNA, Messenger / Q000032:analysis; D017461:Receptors, Atrial Natriuretic Factor / Q000235:genetics / Q000378:metabolism*; D012910:Snake Venoms
chemical_list: C075597:Dendroaspis natriuretic peptide; D004546:Elapid Venoms; D036341:Intercellular Signaling Peptides and Proteins; D007457:Iodine Radioisotopes; D008024:Ligands; D010455:Peptides; D012333:RNA, Messenger; D012910:Snake Venoms; D006162:Guanylate Cyclase; D017461:Receptors, Atrial Natriuretic Factor; C091715:atrial natriuretic factor receptor A