Ventricular natriuretic peptide (VNP), a possibly new type of natriuretic peptide with an extended C-terminal tail, has been isolated from eel cardiac ventricles. We investigated the effects of eel VNP on the kidney and cardiovascular system and compared these results with those of mammalian peptides in dogs. Eel VNP, human (dog) ANP, human and dog BNPs were infused into the renal artery at non-hypotensive doses. All peptides produced similar diuresis and natriuresis, but cardiac output and the left and right ventricular stroke work were decreased by BNPs, but ANP and eel VNP did not change these parameters. Systemic vascular resistance was increased by BNPs, but unaffected by other peptides. These results show that eel VNP has renal effects similar to ANP and BNP, but it elicits responses in the heart different from those of BNPs in anesthetized dogs.