AJP - Renal Physiology, Vol 259, Issue 4 605-F612, Copyright © 1990 by American Physiological Society
Renal atrial natriuretic peptide receptor subtypes in spontaneously hypertensive rats
J. Brown, S. P. Salas and J. M. Polak
Physiological Laboratory, University of Cambridge, United Kingdom.
Receptor subtypes for atrial natriuretic peptide (ANP) were characterized
in kidneys of 18-wk-old Wistar-Kyoto (WKY) and spontaneously hypertensive
rats (SHR) by in vitro autoradiography through use of des[Gln18, Ser19,
Gly20, Leu21, Gly22] ANP-(4-23) (C-ANP) and ANP-(5-25) as subtype-selective
ligands. alpha-125I-ANP (100 pM) bound reversibly but with high affinity to
glomeruli, to stripes in outer medulla, and to inner medulla of both WKY
and SHR. C-ANP (10 microM) inhibited approximately 70% of the glomerular
binding but none of the medullary binding in either strain. All
high-affinity specifically reversible binding sites for alpha-ANP that
bound C-ANP were also bound by 10 microM ANP-(5-25). However, the
specifically reversible binding of alpha-125I-ANP that was not inhibited by
10 microM C-ANP behaved differently in each strain. In WKY, this binding
was weakly inhibited by ANP-(5-25), so that even the presence of 10 microM
ANP-(5-25) did not inhibit some glomerular binding and greater than 40% of
the specifically reversible medullary binding of alpha-125I-ANP. In SHR,
this binding was inhibited by ANP-(5-25) with a significantly higher
affinity so that all specifically reversible binding of alpha-125I-ANP was
inhibited by 10 microM ANP-(5-25). SHR also showed higher affinities but
lower maximum binding capacities for alpha-ANP in their outer cortical
glomeruli and medullas. These results suggest that the preponderant
medullary ANP receptor differs between WKY and SHR. Differences in
glomerular subtypes of ANP receptor may also distinguish WKY and SHR.
