Conventional Vasopressor and Vasopressor-Sparing Strategies to Counteract the Blood Pressure-Lowering Effect of Small Interfering RNA Targeting Angiotensinogen

Estrellita Uijl, Dien Ye, Liwei Ren, Katrina M. Mirabito Colafella, Richard van Veghel, Ingrid M. Garrelds, Hong S. Lu, Alan Daugherty, Ewout J. Hoorn, Paul Nioi, Don Foster, A. H.Jan Danser*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

11 Citations (Scopus)
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Background A single dose of small interfering RNA (siRNA) targeting liver angiotensinogen eliminates hepatic angiotensinogen and lowers blood pressure. Angiotensinogen elimination raises concerns for clinical application because an angiotensin rise is needed to maintain perfusion pressure during hypovolemia. Here, we investigated whether conventional vasopressors can raise arterial pressure after angiotensinogen depletion. Methods and Results Spontaneously hypertensive rats on a low-salt diet were treated with siRNA (10 mg/kg fortnightly) for 4 weeks, supplemented during the final 2 weeks with fludrocortisone (6 mg/kg per day), the α-adrenergic agonist midodrine (4 mg/kg per day), or a high-salt diet (all groups n=6-7). Pressor responsiveness to angiotensin II and norepinephrine was assessed before and after siRNA administration. Blood pressure was measured via radiotelemetry. Depletion of liver angiotensinogen by siRNA lowered plasma angiotensinogen concentrations by 99.2±0.1% and mean arterial pressure by 19 mm Hg. siRNA-mediated blood pressure lowering was rapidly reversed by intravenous angiotensin II or norepinephrine, or gradually reversed by fludrocortisone or high salt intake. Midodrine had no effect. Unexpectedly, fludrocortisone partially restored plasma angiotensinogen concentrations in siRNA-treated rats, and nearly abolished plasma renin concentrations. To investigate whether this angiotensinogen originated from nonhepatic sources, fludrocortisone was administered to mice lacking hepatic angiotensinogen. Fludrocortisone did not increase angiotensinogen in these mice, implying that the rise in angiotensinogen in the siRNA-treated rats must have depended on the liver, most likely reflecting diminished cleavage by renin. Conclusions Intact pressor responsiveness to conventional vasopressors provides pharmacological means to regulate the blood pressure-lowering effect of angiotensinogen siRNA and may support future therapeutic implementation of siRNA.

Original languageEnglish
Article numbere026426
JournalJournal of the American Heart Association
Issue number15
Publication statusPublished - 2 Aug 2022

Bibliographical note

Funding Information:
Drs Nioi and Foster are employees of Alnylam Pharmaceuticals. Dr Danser received a grant from Alnylam Pharmaceuticals, which has partially supported this work. The other authors report no conflicts.

Funding Information:
This work was partially supported by Alnylam Pharmaceuticals. Dr Mirabito Colafella was supported by a National Health and Medical Research Council of Australia CJ Martin Fellowship (number 1112125). Dr Ren was supported by a National Natural Science Foundation of China (grant number 81900668).

Publisher Copyright:
© 2022 The Authors.


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