Metabolic Behavior of Angiotensins in Upright Postures NormotensiyeHuman Plasma in the Supine

The etfect of activating the renin-angietensin system on the metabolism of angiotensins (ANGs) in normotesusiye human plasma was inyestigated. In normotensiye supine human plasma, four peptides with in vitro angietensin I-conyerting enzyme (ACE) inhibitory activity which correspond to the sequence of ANG (3-8), ANG (4-8), ANG (S-8), and ANG (3--4) existed at a concentration of >39 frnellml of p]asma. When actfivating the renin activgty by keeping upright in posture for 60min, ANG II and the four peptides significantly increased as compared with the levels in the supine posture, except for ANG L In particular, Vall-Tyr correspending to ANG (3-4) in the upright posture was about 4-fo)d more than the yalue in the supine posture, and -'as predominantly present (447finolfml of plasma) as well as ANG I. As a result of in vitro degradation tests en ANGs, ANG (3-4) was produced from ANG I, and not from ANG II, III or