Depletion of Tissue Angiotensin-Converting Enzyme Differentially Influences the Intrarenal and Urinary Expression of Angiotensin Peptides
作者:
J. Modrall,
Javid Sadjadi,
K. Brosnihan,
Patricia Gallagher,
Chun-hua Yu,
Gerald Kramer,
Kenneth Bernstein,
Mark Chappell,
期刊:
Hypertension: Journal of The American Heart Association
(OVID Available online 2004)
卷期:
Volume 43,
issue 4
页码: 849-853
ISSN:0194-911X
年代: 2004
出版商: OVID
关键词: angiotensin II;angiotensin I;renin-angiotensin system;mice
数据来源: OVID
摘要:
Abstract—The relative contribution of circulating versus tissue renin-angiotensin systems to the tissue expression of angiotensin peptides in the kidney remains unresolved. To address this issue, intrarenal and urinary levels of the peptide products of the renin-angiotensin system were assessed in a tissue angiotensin-converting enzyme knockout (tisACE−/−) mouse model. Systolic blood pressure was significantly lower (64.6±3.6 versus 81.4±4.5 mm Hg;P<0.02) and urinary volume was increased (7.25±0.86 versus 2.86±0.48 mL/d;P<0.001) intisACE−/−mice compared with wild-type mice. Intrarenal angiotensin II was 80% lower intisACE−/−mice compared with wild-type mice (5.17±0.60 versus 25.5±2.4 fmol/mg protein;P<0.001). Intrarenal angiotensin I levels also declined by a comparable extent (73%) in thetisACE−/−mice (P<0.01). Intrarenal angiotensin-(1–7) concentrations were similar between the strains, but the ratio of intrarenal angiotensin-(1–7) to angiotensin II and angiotensin I intisACE−/−mice increased 470% and 355%, respectively, compared with wild-type mice. Urinary excretion of angiotensin II and angiotensin-(1–7) were not different, but the excretion of angiotensin I increased 270% intisACE−/−mice (P<0.01). These studies suggest 2 potential mechanisms for the reduction of intrarenal angiotensin II intisACE−/−mice: (1) an attenuated capacity to form angiotensin II by renal angiotensin-converting enzyme and (2) significant depletion of its direct precursor angiotensin I in renal tissue. Sustained intrarenal levels of angiotensin-(1–7) may contribute to chronic hypotension and polyuria intisACE−/−mice, particularly in the context of depleted angiotensin II in the kidney.
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