Angiotensin II, independent of plasma renin activity, contributes to the hypertension of autonomic failure

Amy C. Arnold, Luis E. Okamoto, Alfredo Gamboa, Cyndya Shibao, Satish R. Raj, David Robertson, Italo Biaggioni

Research output: Contribution to journalArticle

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Abstract

At least half of primary autonomic failure patients exhibit supine hypertension, despite profound impairments in sympathetic activity. Although the mechanisms underlying this hypertension are unknown, plasma renin activity is often undetectable, suggesting renin-angiotensin (Ang) pathways are not involved. However, because aldosterone levels are preserved, we tested the hypothesis that Ang II is intact and contributes to the hypertension of autonomic failure. Indeed, circulating Ang II was paradoxically increased in hypertensive autonomic failure patients (52±5 pg/m3L, n=11) compared with matched healthy controls (27±4 pg/m3L, n=10; P=0.002), despite similarly low renin activity (0.19±0.06 versus 0.34±0.13 ng/m3L per hour, respectively; P=0.449). To determine the contribution of Ang II to supine hypertension in these patients, we administered the AT1 receptor blocker losartan (50 mg) at bedtime in a randomized, double-blind, placebo-controlled study (n=11). Losartan maximally reduced systolic blood pressure by 32±11 mm Hg at 6 hours after administration (P<0.05), decreased nocturnal urinary sodium excretion (P=0.0461), and did not worsen morning orthostatic tolerance. In contrast, there was no effect of captopril on supine blood pressure in a subset of these patients. These findings suggest that Ang II formation in autonomic failure is independent of plasma renin activity, and perhaps Ang-converting enzyme. Furthermore, these studies suggest that elevations in Ang II contribute to the hypertension of autonomic failure, and provide rationale for the use of AT1 receptor blockers for treatment of these patients.

Original languageEnglish (US)
Pages (from-to)701-706
Number of pages6
JournalHypertension
Volume61
Issue number3
DOIs
StatePublished - Mar 1 2013

Fingerprint

Renin
Angiotensin II
Hypertension
Losartan
Blood Pressure
Captopril
Angiotensins
Peptidyl-Dipeptidase A
Aldosterone
Sodium
Placebos
Therapeutics

All Science Journal Classification (ASJC) codes

  • Internal Medicine

Cite this

Arnold, Amy C. ; Okamoto, Luis E. ; Gamboa, Alfredo ; Shibao, Cyndya ; Raj, Satish R. ; Robertson, David ; Biaggioni, Italo. / Angiotensin II, independent of plasma renin activity, contributes to the hypertension of autonomic failure. In: Hypertension. 2013 ; Vol. 61, No. 3. pp. 701-706.
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Angiotensin II, independent of plasma renin activity, contributes to the hypertension of autonomic failure. / Arnold, Amy C.; Okamoto, Luis E.; Gamboa, Alfredo; Shibao, Cyndya; Raj, Satish R.; Robertson, David; Biaggioni, Italo.

In: Hypertension, Vol. 61, No. 3, 01.03.2013, p. 701-706.

Research output: Contribution to journalArticle

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AU - Robertson, David

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