Plasma concentrations of angiotensin metabolites in young male normotensive and mild hypertensive subjects

The plasma concentrations of angiotensin(Ang) I, Ang II, and their metaboli tes(Ang (3-8), (4-8), (5-8), and (3-4)) following in vitro ACE inhibitory a ctivity were examined in young male normotensive (NT) (n = 7), and mild hyp ertensive (HT) volunteers (n = 6). There were no differences in supine plas ma levels of Ang I, Ang II, and Ang (5-8) between the NT and HT groups: Ang I, 304 +/- 43 fmol/ml vs. 293 +/- 15 fmol/ml; Ang II, 32 +/- 6 fmol/ml vs. 43 +/- 10 fmol/ml; Ang (5-8), 176 +/- 22 fmol/ml vs. 133 +/- 32 fmol/ml. I n addition, there were no significant differences between groups in any of these Ang levels when measured after standing for 60 min. However, the HT g roup showed significantly reduced supine and upright plasma Ang (3-8) and A ng (3-4) levels as compared to the NT group. In particular, the supine plas ma level of Ang (3-4) (71 +/- 13 fmol/ml-plasma) in the HT group was signif icantly (1/3-fold) lower than that in the NT group (197 +/- 35 fmol/ml-plas ma). An inverse correlation between the plasma level of Ang (3-4) and the u pright systolic blood pressure (r = -0.627, p < 0.02, n = 13) was observed, indicating that the metabolism of Ang (3-4) might have been associated wit h the change in blood pressure.