Endogenous angiotensin II and III concentrations in glomerular filtrate, proximal tubule fluid, and star vessel plasma are approximately 1,000-fold higher than in systemic plasma.
Endogenous angiotensin II and III concentrations in intrarenal fluid compartments are approximately 1,000-fold higher than in systemic plasma, suggesting local regulation of renal function independent of systemic angiotensin.
Estimación del efecto: 1,000-fold higher
Tasa de eventos absoluta: 32.8% vs 0.032%
To examine angiotensin (ANG) concentrations in fluid compartments near known intrarenal ANG receptors, we measured ANG concentrations in glomerular filtrate (GF), star vessel plasma (SVP), and luminal fluid from the early, mid, and late proximal tubule (E, M, and L PT). Samples were collected from euvolemic Munich-Wistar rats by free-flow micropuncture; ANG concentrations were measured by RIA. In one group of rats, concentrations of total immunoreactive ANG (reflecting ANG II and lesser amounts of three fragments) in GF and E, M, and L PT fluid averaged 29-40 nM compared with 32 pM in systemic plasma. In a second group, immunoreactive ANG concentrations in SVP also exceeded systemic levels by a factor of 1,000. In a final group, samples of GF and LPT fluid were purified by HPLC before RIA to measure ANG II and III concentrations specifically: their respective concentrations were 6-8 nM and 14-25 nM. We interpret these results to indicate that substantial amounts of ANG peptides are released into or generated within intrarenal fluid compartments, in which local ANG is likely to effect regulation of renal function independently of systemic ANG.
Seikaly et al. (Mon,) conducted a other in Normal physiology (n=39). Intrarenal fluid compartments (glomerular filtrate, proximal tubule, star vessel) vs. Systemic arterial plasma was evaluated on Total immunoreactive angiotensin concentration (1,000-fold higher). Endogenous angiotensin II and III concentrations in glomerular filtrate, proximal tubule fluid, and star vessel plasma are approximately 1,000-fold higher than in systemic plasma.