AJP - Endocrinology and Metabolism, Vol 257, Issue 5 E675-E680, Copyright © 1989 by American Physiological Society
Atrial natriuretic peptide stimulates submandibular gland synthesis and secretion of cGMP
L. Jeandel, E. Morrier and S. Heisler
Unite de Bioregulation Cellulaire, Le Centre Hospitalier de l'Universite Laval, Sainte-Foy, Quebec, Canada.
Binding of atrial natriuretic peptide (ANP) to rat submandibular gland and
its effect on guanosine 3',5'-cyclic monophosphate (cGMP) formation and
salivary secretion were investigated. Membranes rapidly and specifically
bound 125I-ANP. Binding was inhibited by unlabeled ANP (IC50 approximately
1.6 nM), but not by atriopeptin I, other COOH- and NH2-terminal deleted ANP
fragments, or agents such as pilocarpine or substance P. Scatchard analysis
revealed a single class of high-affinity sites (dissociation constant 0.74
+/- 0.25 nM; maximal binding capacity 20.5 +/- 6.3 pmol/mg protein).
Intravenous infusion of ANP with pilocarpine caused a significant
dose-dependent increase in the levels of cGMP detected in plasma and
saliva. Because salivary cGMP may have originated in plasma, the effect of
ANP on cGMP formation was evaluated in dispersed cells. ANP evoked a
concentration-dependent increase in both cGMP synthesis and secretion (EC50
approximately 1.7 x 10(-8) M). The atrial peptide did affect basal or
l-isoproterenol-stimulated adenosine 3',5'-cyclic monophosphate synthesis
in dispersed cells. When infused by itself and/or with pilocarpine, ANP did
not alter the rate of spontaneous or pilocarpine-induced salivary flow,
secretion of chloride, or protein release. The data demonstrate the
presence of guanylate cyclase-coupled ANP receptors in submandibular gland;
the atrial peptide, however, does not exert an effect of the secretory
function of the gland.
