AJP - Regulatory, Integrative and Comparative Physiology, Vol 258, Issue 4 1078-R1083, Copyright © 1990 by American Physiological Society
Distribution of atrial natriuretic peptide receptor subtypes in rat brain
J. Brown and A. Czarnecki
Physiological Laboratory, Cambridge, United Kingdom.
The presence and distribution of atrial natriuretic peptide (ANP) clearance
receptors in rat brain were investigated by use of
des[Gln18,Ser19,Gly20,Leu21,Gly22]ANP-(4-2 3) (C-ANP), a specific ligand of
this receptor, to displace bound alpha-125I-labeled ANP. alpha-125I-ANP
(200 pM) bound significantly to arachnoid mater, subfornical organ, choroid
plexus, area postrema, median preoptic nucleus, and supraoptic and
paraventricular nuclei. Binding was reversible at all sites with unlabeled
alpha-ANP. Binding dissociation constants for alpha-ANP were measured for
the first three sites and were all in the nanomolar range. C-ANP competed
with alpha-125I-ANP only for binding sites on arachnoid mater, 1 microM
C-ANP displacing radioligand from at least 60% of these sites. No
alpha-125I-ANP was displaced by completely unrelated peptides. The
reversible binding of 125I-Tyr0-ANP-(5-25), another relatively selective
ligand of the clearance receptor, was also concentrated on arachnoid mater.
Therefore, high-affinity binding sites for alpha-ANP on arachnoid mater may
be clearance receptors for ANP.
