Question special

It appears the positive vasopressor physiologic effects of Angiotension II have been known since the 1960's, what delayed the translation to or study in further clinical trials or brought it to light as a potentially new target now? (Ref:Cohn JN, Luria MH. Studies in clinical shock and hypotension. II. Hemodynamic effects of norepinephrine and angiotensin. J Clin Invest. 1965;44:1494–504.)