Peptide antagonists of angiotensin-induced adrenal catecholamine release

摘要: Abstract The effect of analogs angiotensin (modified with an Ile-substituted for Phe) was studied in the isolated, retrogradely perfused adrenal cat. Continuous differential analysis norepinephrine and epinephrine output quantified automated trihydroxyindole procedure. [Ile8]-angiotensin I [Ile7]-angiotensin III exhibited negligible secretory activity, contrast to stimulatory effects II (10–20% activity relative II). blocked II-induced catecholamine secretion a pA2 value 8.50 obtained. especially potent antagonist 10.4 calculated this heptapeptide analog. II, partial agonist medulla 9.33. These three were equally effective against induced by corresponding unsubstituted homologs (Ang Ang III). data suggest that all these peptides interact common receptor. had no on medullary responses KCl, nicotine bradykinin. structural are pure competitive antagonists cat chromaffin cell.