RAINBOW-TROUT VENTRICULAR NATRIURETIC PEPTIDE - ISOLATION, SEQUENCING, AND DETERMINATION OF BIOLOGICAL-ACTIVITY

Ventricular natriuretic peptide (VNP) is a new type of cardiac natriur etic peptide initially isolated from the eel ventricle. VNP has been i solated from cardiac ventricles of the rainbow trout, Oncorhynchus myk iss, and found to consist of 35 amino acid residues carrying a C-termi nal tail sequence with 14 amino acid residues. Thus, the long C-termin al sequence characteristic of VNP was also conserved in the trout VNP. A VNP with 4 amino acid residues truncated from the C-terminus was al so isolated from trout ventricles and sequenced. Sequence identity of trout VNP to eel VNP was 77%, while it was 56% to eel A-type natriuret ic peptide (ANP). Trout VNP caused characteristic biphasic vasopressor /depressor effects in the trout similar to those produced by rat and e el ANP. Trout VNP and human ANP were almost equipotent in their vasopr essor and depressor activity in trout. Unlike eel VNP, therefore, homo logous VNP did not exhibit greater activity in the trout. In the rat, however, trout VNP was more potent than eel peptide and was almost equ ipotent to human ANP for both vasodepressor and natriuretic effects. T he high potency of trout VNP appears to be due in part to its longer-l asting effect compared to human ANP. (C) 1994 Academic Press, Inc.