Autoradiographic visualization of the natriuretic peptide receptor-B in rat tissues.
Natriuretic peptide receptor-B (NPRB) was visualized in rat tissues by in vitro autoradiography, using its putative physiological agonist C-type natriuretic peptide (CNP). In initial studies, we determined that atrial natriuretic peptide (ANP) is not a suitable ligand for labeling the NPRB: in tissues reported to contain NPRB transcripts, CNP did not inhibit [125I]ANP binding except to NPRC sites. Therefore, to visualize the NPRB we used 125I[Tyr(o)]-CNP as a radioligand with an excess of NPRC-blocking peptide: C-ANP. With this approach we detected the highest number of NPRB-like sites in the pars intermedia of the pituitary gland. A large number of these sites were present in pituitary neural and anterior lobes, area postrema, adrenal medulla and cortex. A moderate NPRB population was observed in the subfornical organ, plexiform layer of the olfactory bulb and kidney. Low concentrations of NPRB were noted in the cerebellum and cerebrum but not in the choroid plexus and pia-arachnoid. Saturation experiments performed on cerebellum sections revealed a very low concentration (Bmax 4.8 fmol/mg protein) of high affinity (Kd 1.2 nM) NPRB-like sites. This study is the first demonstration of 125I[Tyr(o)]-CNP binding sites with characteristics of the NPRB in intact tissues.
Laboratory of Pathobiology, Clinical Research Institute of Montreal, Canada.
E M
EM
Konrad
G
G
Thibault
E L
EL
Schiffrin
D000311:Adrenal Glands / Q000378:metabolism; D000818:Animals; D009320:Atrial Natriuretic Factor / Q000378:metabolism; D001345:Autoradiography; D001667:Binding, Competitive; D001921:Brain / Q000378:metabolism; D006162:Guanylate Cyclase / Q000378:metabolism*; D007668:Kidney / Q000378:metabolism; D007700:Kinetics; D020097:Natriuretic Peptide, Brain; D020098:Natriuretic Peptide, C-Type; D009419:Nerve Tissue Proteins / Q000378:metabolism; D010902:Pituitary Gland / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D017461:Receptors, Atrial Natriuretic Factor / Q000378:metabolism*; D014018:Tissue Distribution
D009419:Nerve Tissue Proteins; D020097:Natriuretic Peptide, Brain; D020098:Natriuretic Peptide, C-Type; D009320:Atrial Natriuretic Factor; D006162:Guanylate Cyclase; D017461:Receptors, Atrial Natriuretic Factor; C073616:atrial natriuretic factor receptor C