Renal Salt Handling in Postural Tachycardia Syndrome Following Dietary Dopa Administration

NCT ID: NCT01064739

Last Updated: 2016-05-26

Basic Information

• Recruitment Status: COMPLETED
• Clinical Phase: EARLY_PHASE1
• Total Enrollment: 14 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2007-01-31
• Study Completion Date: 2012-12-31

Brief Summary

The purpose of this study is to learn how plants can play a role in gain/loss of sodium in the urine and in the regulation of blood pressure. Dopamine is a chemical mostly present in the brain and kidneys which assists in regulation of the body's salts (sodium and potassium). Fava beans contain a lot of the chemical that increases the production of dopamine by the kidneys.

The purpose of these studies is to characterize the diuretic effects of dietary catecholamine sources in healthy individuals. Specific aims are:

1. To determine the effect of dietary dopa sources on plasma and urinary catecholamines.

2. To investigate the capacity of botanical dopaminergic agents (fava beans) to induce natriuresis in a short term study.

3. To provide preliminary data on the effects of dietary dopa on heart rate and blood pressure.

In these studies, we will test the null hypothesis (Ho) that urinary sodium excretion will not differ in healthy volunteers after consumption of a fixed-sodium study diet and the study diet plus fava beans.

Detailed Description

Fava beans are a broad bean, with potential clinical relevance in Parkinson's patients since they contain high levels of the dopamine precursor, dihydroxyphenylalanine (dopa).In addition to the central nervous system functions of dopamine that are compromised in Parkinson's disease, renal dopamine has vasodilatory and natriuretic activity. Elevated urinary dopamine, however, does not consistently correlate with increased urinary sodium excretion, and there are conflicting opinions over the conditions under which renal dopamine might regulate sodium balance.The goal of our study was to clarify the natriuretic effect of fava beans, obtained from a source that serves patients with Parkinson's disease. Catechol and sodium data were compared in healthy volunteers using a longitudinal design in which all participants consumed a fixed sodium study diet on day 1 and the fixed sodium diet plus fava beans on day 2. Blood was sampled at 1, 2, 4 and 6 hours after breakfast, and three consecutive 4-hr urine samples were collected.

Postural tachycardia syndrome (POTS) is the most common form of orthostatic intolerance, affecting an estimated 500,000 Americans, principally young women. POTS refers to an excessive increase in heart rate (>30 beats per minute) on standing in the absence of orthostatic hypotension. Previous findings by the Robertson/Garland research group suggest that mechanisms involved in orthostatic and absolute volume regulation contribute to POTS pathophysiology. A follow-up study might compare the influences of diet in patients with POTS and healthy volunteers.

Conditions

Healthy Participants

Study Design

• Allocation Method: NA
• Intervention Model: SINGLE_GROUP
• Blinding Strategy: NONE

Study Groups

Study Diet +/- fava beans

Participants underwent testing while on a methylxanthine-free diet providing 150 mEq sodium and 75 mEq potassium per day. The study involved a longitudinal design where the participants served as their own controls. Subjects consumed the standard fixed sodium diet on study day one. On study day two, participants ate 100 g of puréed fava beans and pods with study diet at breakfast (0800hr) and lunch (1200hr).

Group Type: EXPERIMENTAL

Fava beans

Intervention Type: DIETARY_SUPPLEMENT

Participants will receive 100g of fresh fava beans for breakfast and lunch on one study day and prior to this study day will be restricted to a fixed sodium low monoamine diet

Fixed Sodium Diet

Intervention Type: OTHER

Fixed sodium low monoamine diet

Interventions

Fava beans

Participants will receive 100g of fresh fava beans for breakfast and lunch on one study day and prior to this study day will be restricted to a fixed sodium low monoamine diet

Intervention Type: DIETARY_SUPPLEMENT

Fixed Sodium Diet

Fixed sodium low monoamine diet

Intervention Type: OTHER

Eligibility Criteria

Inclusion Criteria

• Non-smoking
• Free of medications with the potential to influence BP
• Age between 18-60 years
• Male and female subjects are eligible
• Able and willing to provide informed consent

Exclusion Criteria

• Significant cardiovascular, pulmonary, hepatic, or hematological disease by history or screening results
• Positive urine b-hcg pregnancy test
• Evidence of cardiac structural disease (by clinical examination or prior echocardiogram)
• Hypertension defined as a BP>145/95 (off medications) or need for antihypertensive medications
• Evidence of significant conduction system delay (QRS duration >120 ms) on electrocardiogram
• Inability to give, or withdraw, informed consent
• Other factors which in the investigator's opinion would prevent the subject from completing the protocol Food allergies to favas or other dietary dopa sources selected
• Parkinson's Disease
• Diagnosis of Glucose-6-Phosphate Dehydrogenase (G6P) Deficiency or Individuals from the Mediterranean with family history of G6PD.
• Prolonged QT interval on ECG> 480 13. Familial history of sudden cardiac death

• Minimum Eligible Age: 18 Years
• Maximum Eligible Age: 60 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: Yes

Sponsors

Vanderbilt University

OTHER

Sponsor Role: lead

Responsible Party

Emily M. Garland

Research Associate Professor

Responsibility Role: PRINCIPAL_INVESTIGATOR

Principal Investigators

Emily M Garland, PhD

Role: PRINCIPAL_INVESTIGATOR

Vanderbilt University Medical Center

Locations

Vanderbilt University Clinical Research Center

Nashville, Tennessee, United States

Countries

United States

References

Garland EM, Cesar TS, Lonce S, Ferguson MC, Robertson D. An increase in renal dopamine does not stimulate natriuresis after fava bean ingestion. Am J Clin Nutr. 2013 May;97(5):1144-50. doi: 10.3945/ajcn.112.048470. Epub 2013 Apr 3.

Reference Type: DERIVED

PMID: 23553159 (View on PubMed)

Other Identifiers

PN 1767

Identifier Type: -

Identifier Source: org_study_id