The distribution of atrial natriuretic peptide receptor B (ANPR-B) var
ies between tissues and species. The aim of this study is to determine
whether ANPR-B is present in the hamster glomeruli. In vitro C-type n
atriuretic peptide (CNP)and atrial natriuretic factor (ANF)-stimulated
cGMP accumulation studies were performed in hamster glomeruli. Elevat
ed cGMP accumulations were observed upon ANF addition. No cGMP respons
e was seen with CNP. Competitive receptor-binding experiments were per
formed with I-125-CNP and I-125-ANF against their respective cold pept
ides in hamster glomeruli. Although no CNP binding was detected, posit
ive ANF binding was found and two types of ANF receptor were demonstra
ted. The affinity (K-dl) and maximum binding capacity (B-maxl) of the
high-affinity ANF receptor were 0.014 +/- 0.001 nM and 60.4 +/- 10.2 f
mol/mg protein, respectively. Those of the low-affinity receptor (K-d2
and B-max2) were 45.7 +/- 6.2 nM and 28.3 +/- 6.3 pmol/mg protein, re
spectively. Similarly, saturation binding experiments also failed to s
how any CNP receptor binding in hamster glomeruli. This finding sugges
ts that ANPR-B is not present in hamster glomeruli and CNP is not a di
rect physiological regulator of hamster renal function.