Identification of a pressor polypeptide in human amniotic fluid

Abstract It has been suggested that a new, highly active pressor polypeptide can be generated by the incubation of human amniotic fluid. The present report deals with the identification of this polypeptide through separation by gel filtration in Sephadex G-15 and by paper chromatographic techniques. Inhibition of its pressor effect when incubated with antibody against angiotensin I and II was also studied. Separation with Sephadex yielded three peaks of pressor material, while paper chromatography showed this pressor material to have an Rf different from that of angiotensin I or II. Nevertheless, it was concluded that this pressor material is angiotensin, one of its analogues, or a fragment of the polypeptide since its pressor effect was inhibited by antibody against angiotensin. Further, the pressor activity reappeared after destruction of antibody by boiling.