Renin and Angiotensin Tachyphylaxis

Abstract

Tn the conscious dog, synthetic angioteiisin and crude hog renin produce dose-response curves which run strictly parallel if the max imum blood pressure attained is taken as the parameter. Repeated injections of small or medium closes of angioteitsiri or of small doses of renin do not l)roduce tachyphylaxis. In contrast, high closes of renin, as well as of angiotensin, diminish or abolish the pressor response to subsequent injections of the same substances. Furthermore, cros.s tachyphylaxis between renin and arigiotensin can be demon strated. infusions of renin and angiotensin in various dosages elicit characteristic blood pressure changes, which are very similar for both substances and also display tachyphy laxis at sufficiently high doses. It is concluded that so-called renin tachyphylaxis is, in fact, due to a diminished response to angiotensin. This might be takeii as an indirect proof that renin liberates aiigiotensiri not only iii vitro hut. also in the organism.