AJP - Renal Physiology, Vol 250, Issue 3 573-F578, Copyright © 1986 by American Physiological Society
Localization of atrial natriuretic peptide binding sites within the rat kidney
D. P. Healy and D. D. Fanestil
Although synthetic atrial natriuretic peptides (ANP) have potent
natriuretic/diuretic properties, the renal mechanisms underlying these
effects are not yet clearly defined. To determine the possible sites of
action for ANP within the kidney, we have localized 125I-ANP binding sites
by in vitro autoradiography. Slices of rat kidney were incubated with 150
pM 125I-ANP [alpha-rat ANP (alpha-rANP), 28 amino acids] alone or in the
presence of 10 nM or 1 microM unlabeled ANP. Autoradiography was performed
using LKB Ultrofilm or emulsion-coated cover slips together with
histochemical/immunohistochemical staining of specific tubular segments.
High-affinity 125I-ANP binding sites were concentrated over glomeruli and
to a lesser extent over the arterial vasculature. Lower-affinity binding
sites were seen over proximal tubules and inner medullary collecting ducts.
The remainder of the nephron was unlabeled. The localization of
high-affinity 125I-ANP binding sites in rat kidney is consistent with a
glomerular filtration/hemodynamic mechanism as the principal means by which
ANP promotes natriuresis/diuresis.
