The Role of Mineralocorticoid Receptors in Vascular Function

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT00759525
Recruitment Status : Completed
First Posted : September 25, 2008
Results First Posted : May 28, 2015
Last Update Posted : October 26, 2016
Information provided by (Responsible Party):
Joshua A. Beckman, MD, Brigham and Women's Hospital

Brief Summary:
The purpose of this study is to figure out how decreasing the activity of 11-beta hydroxysteroid dehydrogenase (11-beta HSD) will affect your blood vessel function. 11-beta HSD, which is found in the kidneys and blood vessels, is a natural protein that when active helps to keep your blood pressure under control.

Condition or disease Intervention/treatment Phase
Apparent Mineralocorticoid Excess (AME) Drug: Glycyrrhetic Acid Drug: Placebo Phase 2 Phase 3

Detailed Description:

This study intends to determine whether activation of mineralocorticoid receptors affects vascular function. Vascular function relies on two components of the blood vessel: the inner lining (endothelium) and the vascular smooth muscle. In specific aim 1, we seek to determine if that inhibition of the enzyme 11-beta hydroxysteroid dehydrogenase (11-beta-HSD) will impair endothelium-dependent vasodilation and/or vascular smooth muscle function.

The syndrome of apparent mineralocorticoid excess (AME) is a rare disorder identified in approximately 50 individuals characterized by low-aldosterone hypertension, associated with low renin and hypokalemia These subjects avidly retain salt and water, have suppression of both plasma renin and aldosterone levels, but clinically appear as though they have a state of mineralocorticoid excess. A detailed series of investigations has elucidated the cause of this syndrome: severe attenuation of the enzyme 11 beta-hydroxysteroid dehydrogenase (11-beta-HSD). 11-beta-HSD converts cortisol, able to activate mineralocorticoid receptors to cortisone, which cannot. This abnormality can be identified by measuring an abnormal ratio of urinary breakdown products of cortisol and cortisone. Subjects with AME have a high ratio indicative of elevated cortisol concentrations.

Although classical AME is a rare syndrome with a specific recessive inheritance, several other mutations have been identified which cause a varying severity of disease. Recent evidence has suggested mild abnormalities in this pathway may be much more common. In fact two studies have demonstrated that subjects with essential hypertension had greater levels of cortisol/cortisone urinary levels than matched controls. Thus, mild abnormalities of this enzyme may be an important contributor to a segment of patients with high blood pressure. Further, this is the pathway by which consumption of excess black licorice causes hypertension. Black licorice contains glycyrrhizic acid that selectively inhibits 11 beta-HSD. Glycyrrhizic acid is used as a dietary sweetener and sold in "health-food" stores and may also play a epidemiological role in hypertension.

Analogous to the renin-angiotensin system, 11-beta-HSD is not only found in the kidneys, but is found in both vascular endothelial (inner lining) and smooth muscle cells. Hypertension, similar to other risk factors for cardiovascular disease impairs vascular function. One of its major effects is decreasing the bioavailability of endothelium-derived nitric oxide. Nitric oxide contributes importantly to vascular homeostasis by modulating vascular tone, inhibiting both platelet aggregation and coagulation, and inhibition translocation of leukocytes into the vascular wall. Further, patients with hypertension have increased endothelin-1 production and receptor activation. Endothelin-1 antagonizes the beneficial activities of nitric oxide. Experimentally, inactivation of 11 beta-HSD in a rat model has been demonstrated to cause hypertension, increase endothelin receptor A activation and decrease bioavailability of endothelium-derived nitric oxide. Inhibition of mineralocorticoid receptors in this model prevents impairment of vascular function. Thus, in animal models, abnormalities in this pathway may not only cause hypertension, but create an environment favorable to the development and progression of atherosclerosis. Further, recent evidence suggests that activation of this pathway contributes importantly to the morbidity and mortality in patients with congestive heart failure. A large, randomized study demonstrated that a small dose of a mineralocorticoid inhibitor, spironolactone, substantially reduced morbidity and mortality in patients with severe heart failure. Experimentally, spironolactone improved vascular function in patients with congestive heart failure.

Therefore, we seek to characterize the vascular effects of this pathway in humans. This submission involves one protocol: 1) to determine if reversible inhibition of 11 beta-HSD decreases the bioavailability of endothelium-derived nitric oxide and impairs vascular smooth muscle function.

Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 15 participants
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary Purpose: Basic Science
Official Title: The Role of Mineralocorticoid Receptors in Vascular Function
Study Start Date : February 2002
Actual Primary Completion Date : September 2009
Actual Study Completion Date : September 2009

Resource links provided by the National Library of Medicine

U.S. FDA Resources

Arm Intervention/treatment
Active Comparator: 1
Glycyrrhetic Acid
Drug: Glycyrrhetic Acid
130 mg daily for fourteen days
Other Name: licorice root sweetener
Placebo Comparator: 2
Drug: Placebo
Placebo daily for fourteen days

Primary Outcome Measures :
  1. Forearm Blood Flow [ Time Frame: Outcome was measured at the end of each study period (i.e. 14 days after Baseline measurements were taken) ]
    At the end of each 14-day intervention (Glycyrrhinitic acid or Placebo), vascular endothelial function was assessed by measuring forearm blood flow and comparing to Baseline. The outcome measure depicted below reflects the change in forearm blood flow from Baseline after completing the glycyrrhinitic acid regimen as well as the change in forearm blood flow from Baseline after taking the matching placebo.

Information from the National Library of Medicine

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Ages Eligible for Study:   18 Years to 85 Years   (Adult, Senior)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

  • Healthy volunteers

Exclusion Criteria:

  • Blood pressure above 140/90
  • Abnormal physical finding
  • Blood test values for total and LDL cholesterol, CBC, sodium, potassium, creatinine, and glucose laboratories greater 1.5 times normal

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT00759525

United States, Massachusetts
Brigham and Women's Hospital
Boston, Massachusetts, United States, 02115
Sponsors and Collaborators
Brigham and Women's Hospital
Principal Investigator: Joshua A Beckman, MD Brigham and Women's Hospital

Additional Information:
Publications of Results:
Responsible Party: Joshua A. Beckman, MD, Principal Investigator, Brigham and Women's Hospital Identifier: NCT00759525     History of Changes
Other Study ID Numbers: 2001-P-001404
First Posted: September 25, 2008    Key Record Dates
Results First Posted: May 28, 2015
Last Update Posted: October 26, 2016
Last Verified: September 2016

Additional relevant MeSH terms:
Mineralocorticoid Excess Syndrome, Apparent
Adrenocortical Hyperfunction
Adrenal Gland Diseases
Endocrine System Diseases
Steroid Metabolism, Inborn Errors
Metabolism, Inborn Errors
Genetic Diseases, Inborn
Metabolic Diseases
Glycyrrhetinic Acid
Hormones, Hormone Substitutes, and Hormone Antagonists
Physiological Effects of Drugs
Anti-Inflammatory Agents