Natriuretic peptides inhibit adenylyl cyclase activity in dispersed eel gill cells

The effect of natriuretic peptides on forskolin-evoked adenylyl cyclase activity was investigated in dispersed gill cells from the Australian short-finned eel (Anguilla australis). Molecular cloning techniques were employed to identify the putative G-protein-activating motif within the intracellular domain of the eel natriuretic peptide C receptor. Eel ANP, eel CNP and the NPR-C-specific C-ANF inhibited the forskolin-stimulated production of cyclic AMP. This effect was abolished by pretreatment of cells with pertussis toxin. Eel VNP was without effect on adenylyl cyclase activity. PCR and molecular cloning indicated that the intracellular domain of A. australis NPR-C has the same amino acid sequence as Anguilla japonica. Alignment of these sequences with Rattus norvegicus NPR-C indicated conservation of the putative G-protein-activating motif BB...BBXXB (B=basic, X=nonbasic residues). These data suggest that branchially-expressed NPR-C may play a physiological role additional to that of ligand clearance.