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Blood Pressure Response to Sodium in the Diet

This study is currently recruiting participants.
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Verified October 2016 by Robert M. Carey, MD, University of Virginia
National Heart, Lung, and Blood Institute (NHLBI)
Information provided by (Responsible Party):
Robert M. Carey, MD, University of Virginia Identifier:
First received: January 22, 2013
Last updated: October 14, 2016
Last verified: October 2016

Previous studies have demonstrated that single nucleotide polymorphisms (SNPs) of the sodium-bicarbonate co-transporter gene (SLC4A5) are associated with hypertension. We tested the hypothesis that SNPs in SLC4A5 are associated with salt sensitivity of blood pressure in 185 whites consuming an isocaloric constant diet with a randomized order of 7 days of low sodium (Na+) and 7 days of high Na+ intake. Salt sensitivity was defined as a ≥7-mm Hg increase in mean arterial pressure during a randomized transition between low and high Na+ diet.

A total of 35 polymorphisms in 17 candidate genes were assayed, 25 of which were tested for association. Association analyses with salt sensitivity revealed 3 variants that associated with salt sensitivity. Of these, 2 SNPs in SLC4A5 (rs7571842 and rs10177833) demonstrated highly significant results and large effects sizes, using logistic regression. These 2 SNPs had P values of 1.0×10−4 and 3.1×10−4 with odds ratios of 0.221 and 0.221 in unadjusted regression models, respectively, with the G allele at both sites conferring protection. These SNPs remained significant after adjusting for body mass index and age (P=8.9×10−5 and 2.6×10−4 and odds ratios 0.210 and 0.286, respectively). Furthermore, the association of these SNPs with salt sensitivity was replicated in a second hypertensive population. Meta-analysis demonstrated significant associations of both SNPs with salt sensitivity (rs7571842 [P=1.2×10−5]; rs1017783 [P=1.1×10−4]).

In conclusion, SLC4A5 variants are strongly associated with salt sensitivity of blood pressure in 2 separate white populations.

Condition Intervention
Hypertension Other: High sodium diet and low sodium diet

Study Type: Interventional
Study Design: Intervention Model: Single Group Assignment
Masking: None (Open Label)
Primary Purpose: Diagnostic
Official Title: D1 and AT1 Receptor Interaction in Human Hypertension: Sodium Sensitivity of Blood Pressure

Further study details as provided by Robert M. Carey, MD, University of Virginia:

Primary Outcome Measures:
  • Blood pressure; Change in Mean Arterial Pressure from low salt diet to high salt diet [ Time Frame: Study subjects will be observed 5 times during the 2 week intervention ]
    The mean arterial pressure that will determine salt sensitivity will be assessed during the last day of the diet week. The study will be stopped for any individual during any visit if there is an average blood pressure of >180/114 mmHg.

Secondary Outcome Measures:
  • Urine sodium [ Time Frame: Urine chemistry analysis will be assessed from a 24-hour urine collection on the last day of each diet week. ]
  • Genetic analysis for specified genes associated with hypertension [ Time Frame: During the screening visit ]

Estimated Enrollment: 400
Study Start Date: January 2005
Estimated Study Completion Date: August 2021
Estimated Primary Completion Date: August 2021 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Experimental: High sodium diet and low sodium diet
Each subject experiences both a high sodium and a low sodium diet.
Other: High sodium diet and low sodium diet
Isocaloric diet with 60 mEq of potassium and 1gm protein/kg body weight with high sodium 300mEq; low sodium 10 mEq.

Detailed Description:
Subjects are placed on an isocaloric diet, one week with high sodium(300mEq) and one week with low sodium(10mEq), in randomized order. Twenty-four hour urine sodium and urine creatinine levels verify diet compliance. Blood pressure measurements are recorded during each diet week by automated blood pressure monitoring system. Each blood pressure is taken in the right arm 3 times while the subject is sitting quietly for 45 minutes .

Ages Eligible for Study:   18 Years to 70 Years   (Adult, Senior)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

  • Ages 18-70 (inclusive)
  • Sex Male and female
  • Race Caucasian and African-American/black
  • BMI 18.-0-29.9
  • BP Normal

Exclusion Criteria:

  • hypertension
  • blood pressure > 140/90 mmHg
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its identifier: NCT01899495

United States, Virginia
University of Virginia Recruiting
Charlottesville, Virginia, United States, 22903
Contact: Mahabuba Akhter, M.B.B.S, MS    434-924-8757   
Principal Investigator: Robert M Carey, MD         
Sponsors and Collaborators
University of Virginia
National Heart, Lung, and Blood Institute (NHLBI)
Principal Investigator: Robert M Carey, MD University of Virginia
  More Information


Responsible Party: Robert M. Carey, MD, Professor of Medicine; Dean, Emeritus; University Professor Division of Endocrinology and Metabolism, University of Virginia Identifier: NCT01899495     History of Changes
Other Study ID Numbers: 11494
P01HL074940 ( U.S. NIH Grant/Contract )
Study First Received: January 22, 2013
Last Updated: October 14, 2016
Individual Participant Data (IPD) Sharing Statement:
Plan to Share IPD: Undecided

Keywords provided by Robert M. Carey, MD, University of Virginia:
blood pressure
salt sensitivity

Additional relevant MeSH terms:
Vascular Diseases
Cardiovascular Diseases processed this record on September 21, 2017