Natriuretic peptide receptors in the central vasculature of the toad, Bufomarinus

Natriuretic peptide receptors in the central vasculature of the toad, Bufo marinus, were characterized using autoradiographical, molecular, and physio logical techniques. Specific I-125-rat ANP binding sites were present in th e carotid and pulmonary arteries, the lateral aorta, the pre- and post-cava , and the jugular vein, and generally occurred in each layer of the blood v essel. The I-125-rat ANP binding was partially displaced by the specific na triuretic peptide receptor C ligand, C-ANF, which indicates the presence of two types of natriuretic peptide receptors in the blood vessels. This was confirmed by a RT-PCR study, which demonstrated that guanylyl cyclase recep tor (NPR-GC) and NPR-C mRNAs are expressed in arteries and veins. An in vit ro guanylyl cyclase assay showed that frog ANP stimulated the production of cGMP in arterial membrane fractions. Physiological recordings from isolate d segments of the carotid and pulmonary arteries and the lateral aorta, whi ch had been pre-constricted with arginine vasotocin, showed that rat ANP, f rog ANP and porcine CNP relaxed the vascular smooth muscle with relatively similar potency. Together, the data show that the central vasculature conta ins two types of natriuretic peptide receptors (NPR-C and NPR-GC) and that the vasculature is a target for ANP and CNP. (C) 2001 Elsevier Science Inc. All rights reserved.