The natriuretic peptide (ovCNP-39) from platypus (Ornithorhynchus anatinus) venom relaxes the isolated rat uterus and promotes oedema and mast cell histamine release.

In this study we characterise the ability of a C-type natriuretic peptide from platypus (Ornithorhynchus anatinus) venom (ovCNP-39) to relax the rat uterus in vitro and we investigate the possibility that ovCNP-39 contributes to the acute effects of envenomation, which include oedema, pain and erythema. We have found that both ovCNP-39 and the endogenous C-type natriuretic peptide, CNP-22, produce oedema in the rat paw and release histamine from rat peritoneal mast cells. Two synthetic peptides, ovCNP-39(1-17) and ovCNP-39(18-39), corresponding to the N- and C-termini, respectively, are equipotent histamine releasers, suggesting that ovCNP-39 and other natriuretic peptides do not act through conventional natriuretic peptide receptors on mast cells.