Clinical trial NCT01996449: The Role of Aldosterone on Augmented Exercise Pressor Reflex in Hypertension
Official title: The Role of Aldosterone on Augmented Exercise Pressor Reflex in Hypertension
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: PHASE2
Conditions: Hypertension
Keywords: Hypertension
blood pressure
Aldosterone
Eplerenone
Amlodipine
Primary aldosteronism
Exercise pressor reflex
handgrip exercise
passive arm cycling
active arm cycling
Lead sponsor: University of Texas Southwestern Medical Center
Sponsor class: OTHER
First posted: 2013-11-27
Enrollment: 14
Sex: ALL
Minimum age (years): 18
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: CROSSOVER
Primary purpose: BASIC_SCIENCE

Brief summary: Hypertensive patients often show an exaggerated rise in blood pressure during exercise through overactivity of the exercise pressor reflex. An increasing body of evidence suggests a role for aldosterone in augmenting the exercise pressor reflex in hypertensive humans. We hypothesize that this effect of aldosterone is mediated by its direct action on the central nervous system and that administration of mineralocorticoid receptor antagonists constitute an effective treatment for EPR overactivity in hypertension, independent of reductions in resting BP.

Detailed description: Hypertensive patients are known to display exaggerated rise in blood pressure (BP) during exercise but the underlying mechanisms are poorly understood.

Traditionally, muscle afferents were dichotomized as metaboreceptors, which are activated slowly and only during intense or ischemic muscle contraction, or mechanoreceptors, which respond quickly to even mild deformation of their receptive fields. The increase in sympathetic nerve activity and BP caused by activation of these receptors, known as exercise pressor reflex, is normally buffered by activation arterial baroreceptors, which are reset to operate at higher BP range but at the same level of sensitivity. Mechanisms responsible for overactive exercise pressor reflex in hypertension remain unknown, but an increasing body of evidence suggested a role for aldosterone in regulating resting central sympathetic outflow in both hypertensive rats and humans.

Experiments will be performed on 3 groups of subjects 1) stage I (140-159/90-99 mmHg) subjects with essential hypertension, 2) stage I hypertensive subjects with Primary Aldosteronism (PA), and 3) normotensive controls. All participants will attend a baseline study visit, which will include a physical examination, a medical history review, vital sign measurements, and blood and urine collection. Small electrodes will be used to measure muscle nerve activity while the subjects perform a series of exercises that include passive arm cycling, active arm cycling, rhythmic hand grip, sustained hand grip and cold pressor test. Muscle blood flow will be measured before and after hand grip exercises.

A subgroup of subjects with essential hypertension and PA will be assigned to receive Eplerenone or Amlodipine on a randomized, double-blinded design. Participants will attend two weeks visits over a period of 16 weeks. Study visits include measurement of vital signs and blood samples collection. After completing 8 weeks on each medication, muscle nerve activity will be measured while performing the same exercises described in the baseline study visit.

Eligibility criteria: Inclusion Criteria:

* Experiments will be performed on 3 groups of nondiabetic human subjects:
* 1) stage I (140-159/90-99 mmHg) subjects with essential hypertension.
* 2) stage I hypertensive subjects with primary aldosteronism
* 3) normotensive controls.

Exclusion Criteria:

* 1) Any evidence of cardiopulmonary disease, left ventricular hypertrophy or systolic dysfunction by echocardiography.
* 2) Blood pressure averaging ≥160/100 mmHg
* 3) Estimated glomerular filtration rate (eGFR) \< 90 mL/min/1.73m2
* 4) Diabetes mellitus or other systemic illness
* 5) Pregnancy
* 6) Hypersensitivity to nitroprusside, phenylephrine, amlodipine or eplerenone
* 7) Any history of substance abuse or current cigarette use
* 8) Any history of psychiatric illness
* 9) History of malignancy

Primary outcomes:
measure: Muscle Sympathetic Nerve Activity at Rest
timeFrame: 8 weeks post treatment initiation
Secondary outcomes:
measure: Muscle Sympathetic Nerve Activity During Exercise
timeFrame: 8 weeks post treatment initiation
Other outcomes:
Locations:
city: Dallas
country: United States
facility: UT Southwestern Medical Center
state: Texas
Study officials:
affiliation: UT Southwestern Medical Center
name: Wanpen Vongpatanasin, MD
role: PRINCIPAL_INVESTIGATOR
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citation: Funder JW, Carey RM, Fardella C, Gomez-Sanchez CE, Mantero F, Stowasser M, Young WF Jr, Montori VM; Endocrine Society. Case detection, diagnosis, and treatment of patients with primary aldosteronism: an endocrine society clinical practice guideline. J Clin Endocrinol Metab. 2008 Sep;93(9):3266-81. doi: 10.1210/jc.2008-0104. Epub 2008 Jun 13.