PLASMA ANGIOTENSINASE ACTIVITY ON ANGIOTENSIN II AND ANALOGUES

Abstract

Summary The effects of plasma angiotensinase activity on α ‐aspartyl‐angio‐ tensin II and three analogues have been studied. All the compounds exhibited biological activity with parallel dose response curves. The pressor responses to each were of similar form and duration. Cross tachyphylaxis exists between all four compounds. In spite of the similarities in biological effects, α ‐aspartyl‐angiotension was inactivated much more rapidly in vitro by plasma angiotensinase than the other three componnds, suggesting that the major enzyme present in plasma is an aminopeptidase. Studies utilising a radioactive analogue of angiotensin ([ 35 S] PTC‐angiotensin) suggest that an endopeptidase of low activity may also be present in plasma.