No evidence for brain renin-angiotensin system activation during DOCA-salt hypertension
Publication Details
Clinical Science
January 2021
Author(s)
Estrellita Uijl1 2, Liwei Ren1 3 4, Katrina M Mirabito Colafella5, Richard van Veghel1, Ingrid M Garrelds1, Oliver Domenig6, Marko Poglitsch6, Ivan Zlatev7, Jae B Kim7, Stephen Huang7, Lauren Melton7, Ewout J Hoorn2, Don Foster7, A H Jan Danser1
Affiliations
1Division of Vascular Medicine and Pharmacology, Department of Internal Medicine, Erasmus MC, University Medical Center Rotterdam, The Netherlands; 2Division of Nephrology and Transplantation, Department of Internal Medicine, Erasmus MC, University Medical Center Rotterdam, The Netherlands; 3Translational Medicine Collaborative Innovation Center, The Second Clinical Medical College (Shenzhen People's Hospital) of Jinan University, Shenzhen, China; 4Department of Physiology, Shenzhen University Health Science Center, Shenzhen University, Shenzhen, China; 5Cardiovascular Program, Biomedicine Discovery Institute and Department of Physiology, Monash University, Melbourne, Australia; 6Attoquant Diagnostics, Vienna, Austria; 7Alnylam Pharmaceuticals, Cambridge, MA, U.S.A
Abstract
Brain renin–angiotensin system (RAS) activation is thought to mediate deoxycorticosterone acetate (DOCA)-salt hypertension, an animal model for human primary hyperaldosteronism. Here, we determined whether brainstem angiotensin II is generated from locally synthesized angiotensinogen and mediates DOCA-salt hypertension. To this end, chronic DOCA-salt-hypertensive rats were treated with liver-directed siRNA targeted to angiotensinogen, the angiotensin II type 1 receptor antagonist valsartan, or the mineralocorticoid receptor antagonist spironolactone (n = 6–8/group). We quantified circulating angiotensinogen and renin by enzyme-kinetic assay, tissue angiotensinogen by Western blotting, and angiotensin metabolites by LC-MS/MS. In rats without DOCA-salt, circulating angiotensin II was detected in all rats, whereas brainstem angiotensin II was detected in 5 out of 7 rats. DOCA-salt increased mean arterial pressure by 19 ± 1 mmHg and suppressed circulating renin and angiotensin II by >90%, while brainstem angiotensin II became undetectable in 5 out of 7 rats (<6 fmol/g). Gene silencing of liver angiotensinogen using siRNA lowered circulating angiotensinogen by 97 ± 0.3%, and made brainstem angiotensin II undetectable in all rats (P<0.05 vs. non-DOCA-salt), although brainstem angiotensinogen remained intact. As expected for this model, neither siRNA nor valsartan attenuated the hypertensive response to DOCA-salt, whereas spironolactone normalized blood pressure and restored brain angiotensin II together with circulating renin and angiotensin II. In conclusion, despite local synthesis of angiotensinogen in the brain, brain angiotensin II depended on circulating angiotensinogen. That DOCA-salt suppressed circulating and brain angiotensin II in parallel, while spironolactone simultaneously increased brain angiotensin II and lowered blood pressure, indicates that DOCA-salt hypertension is not mediated by brain RAS activation.
PMID
33404046
DOI
10.1042/CS20201239
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