Atrial natriuretic peptide (ANP) receptors were characterized in rat u
terus. The binding of [I-125]ANP to uterine membranes was completely c
ompeted for by increasing concentrations of unlabeled ANP (K-d = 0.39
nM) and brain natriuretic peptide (K-d = 1.24 ans) and partially by C-
type natriuretic peptide (CNP; K-d = 80.4 nM), but not by C-ANF. Also,
[I-125]Tyr-CNP bound to uterine membranes was completely competed by
unlabeled CNP (K-d = 1.12 nM). Cross-linking of [I-125]ANP to uterine
membranes revealed the presence of one band of 130 kilodaltons, corres
ponding to the guanylyl cyclase (GC-A and/or GC-B) subtypes of natriur
etic peptide receptors. The presence of messenger RNA coding for genes
of both GC-A and GC-B receptors was shown by quantitative reverse tra
nscriptase polymerase chain reaction. Furthermore, ANP and, to a lesse
r degree, CNP stimulated the production of cGMP in rat uterus. Autorad
iographic studies localized the highest binding of [I-125]ANP in the e
ndometrium, whereas [I-125]Tyr-CNP binding was distributed in the endo
metrium as well as in the myometrium. These results demonstrate that r
at uterine ANP receptors are of the guanylyl cyclase-coupled subtypes.
The uterus is a target of natriuretic peptides where ANP induces its
biological effects through the production of cGMP.