Natriuretic peptide receptors in the fetal rat.
Brown, J., and Z. Zuo.
Physiological Laboratory, Downing Street, Cambridge CB2 3EG
APStracts 2:0063E, 1995.
In vitro autoradiography of rat fetuses from embryonic days 12-19
(E12-E19) showed widespread, high affinity, specific binding sites
for natriuretic peptides. The sites on E16 somites avidly bound C
-type natriuretic peptide (CNP(1-22) ), as well as C-ANP, a synthetic
ligand that selects the NPR-C type of natriuretic peptide receptor.
Most somitic binding sites had high affinity for atrial natriuretic
peptide (ANP(1-28)), confirming their resemblance to NPR-C. A few had
a lower apparent affinity for ANP(1-28) , suggesting they might be
the NPR-B type of receptor. CNP(1-22) was more powerful than ANP(1
-28) as an agonist of guanosine 3,5-cyclic monophosphate (cGMP)
production in somites, and ATP augmented the action of CNP(1-22).
These observations further suggest the presence of NPR-B. However,
cross-linking of 125I-tyro-CNP(1-22) to somitic membranes, followed
by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS
-PAGE), detected only a single binding protein of 64 kDa under
reducing conditions. This is not consistent with intact, 120 kDa NPR
-B. In vitro autoradiography of the binding of natriuretic pepides to
E16 liver implied that both NPR-A and NPR-C-like receptors were
present here . Hepatic cGMP production was most powerfully stimulated
by ANP(1-28), as expected of NPR-A. SDS-PAGE also identified NPR-A
and NPR-C-like proteins in E16 hepatic membranes. Thus, different
natriuretic peptide receptors are expressed by specific fetal
tissues. This may be developmentally significant.
Received 2 November 1994; accepted in final form 23 March 1995.
APS Manuscript Number E451-4.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 19 April 1995.