DISTRIBUTION AND CHARACTERIZATION OF NATRIURETIC PEPTIDE RECEPTORS INTHE GILLS OF THE SPINY DOGFISH, SQUALUS-ACANTHIAS

The distribution and nature of natriuretic peptide receptors (NPR) in the gills of dogfish, Squalus acanthias, were examined by tissue secti on autoradiography, competition analysis, protein electrophoresis, gua nylate cyclase (GC) assays, and molecular cloning. Specific NP binding occurred on the gill filaments, but not on the interbranchial septum or gill arch. The binding was densest on the efferent edge of the gill s. Higher resolution light-microscopic examination of emulsion-coated sections showed that specific binding occurred mainly on the secondary lamellae and filament body and not on the arterial circulation. At le ast two types of NPR were revealed. One is linked to GC since NP bindi ng stimulates the production of cGMP. The GC receptor may be similar t o the NPR-B mammalian receptor since only pCNP stimulated cGMP product ion. The second receptor is not linked to GC and binds the specific li gand C-ANF [rat des(Gln(18), Ser(19), Gly(20), Leu(21), Gly(22))]. The sequence of a cDNA generated using primers based on conserved regions of vertebrate NPR-C had considerable homology with mammalian and eel NPR-C and eel NPR-D. The presence of GC-linked NPR and NPR-C/NPR-D sug gests that the gills are an important target Organ for NP action. (C) 1997 Academic Press.