The concentration of angiotensins I and II in blood from the pulmonary artery and left ventricle of man.

The concentrations of angiotensin I (AI) and II (AII) were determined by radioimmunoassay in blood from the main pulmonary artery (MPA) and left ventricule (LV) of ten subjects with rheumatic valvular heart disease. The levels of AI were consistently higher in MPA plasma (21.8+/-2.4 pmol/1) than in LV plasma (14.7+/-2.0 pmol/1), paired t, P less than 0.001. The levels of AII were consistently lower in MPA plasma (21.8+/-4.7 pmol/1) than in LV plasma (33.8+/-7.2 pmol/1), paired t, P less than 0.001. The AII antiserum cross-reacted with three metabolites of the hormone, [des-Asp1]angiotensin II, [des-(Asp1, Arg2)angiotensin II [des-(Asp1, Arg2 Val,3]angiotensin II. To characterize the nature of circulating AII immunoreactive material, paper chromatography was used to separate AII from its immunoreactive metabolites. The results showed that 84-100% of the AII immunoreactive material from both MPA and LV plasma chromatographed with the mobility of authentic angiotensin II. The mean pulmonary conversion of endogenous AI was 33+/-4.8% and the net extraction of AII by peripheral tissues was 33+/-4.1%.