IN-VITRO PRODUCTION OF ANGIOTENSIN-II BY ISOLATED GLOMERULI

The glomerulus has several components of the renin-angiotensin system (RAS). The purpose of this study was to evaluate the ability of glomer uli isolated from adult Wistar-Kyoto rats to produce angiotensin II (A NG II). When isolated glomeruli were incubated in Krebs buffer, the pe ak concentration of immunoreactive angiotensin (ANG) in the incubation medium, representing simultaneous production and degradation, occurre d after 15 min of incubation (3.98 +/- 0.34 pg.mg protein(-1).15 min(- 1)), of which 18% was ANG II. When I-125-labeled ANG II was incubated with isolated glomeruli, the half-life of ANG II was 6.06 min. Hence, we estimated ANG II production at 3.77 +/- 0.21 pg.mg protein(-1).15 m in(-1). When angiotensinogen-rich serum was added to the incubation me dium, ANG concentration at 15 min increased by 500-fold (1,978 +/- 44 pg.mg protein(-1).15 min(-1), P < 0.001). ANG concentration in the glo merular incubate responded to perturbations known to alter systemic RA S. Enalaprilat, chymostatin, propranolol, and renin antiserum decrease d ANG concentration in glomerular incubate, whereas salt depletion inc reased this (P < 0.05). We conclude that the rat glomerulus can genera te ANG II independent of neural, hormonal, or vascular control.