Dietary Sodium, Oxidative Stress, and Pulsatile Hemodynamics

Overview

High sodium diets impair vascular function, which may influence the work of the heart. This investigation is designed to determine if this change in vascular function results in a greater workload in the heart and if people who regularly exercise are protected from these effects.

Full Title of Study: “The Role of Oxidative Stress and Endothelial Dysfunction in High Sodium-Induced Changes in Pulsatile Hemodynamics”

Study Type

  • Study Type: Interventional
  • Study Design
    • Allocation: Randomized
    • Intervention Model: Crossover Assignment
    • Primary Purpose: Prevention
    • Masking: Double (Participant, Outcomes Assessor)
  • Study Primary Completion Date: December 31, 2021

Detailed Description

Excess dietary sodium is associated with cardiac hypertrophy independent of changes in blood pressure. Importantly, increased arterial pulsatile load predicts left ventricular hypertrophy, and thus presents a potential mechanism through which high dietary sodium augments cardiovascular disease risk.

While high sodium diets impair vascular function via an increase in oxidative stress, how high sodium influences central pulsatile hemodynamics is not known. This project aims to a) determine how impaired vascular function affects pulsatile hemodynamics and thus influences the work of the heart during periods of high sodium consumption and b) examine whether regular aerobic exercise and/or fitness protects against the deleterious effects of excess sodium.

Interventions

  • Dietary Supplement: High Sodium
    • 10 days of 3900 mg of sodium/day in excess of normal dietary intake delivered via enteric capsules filled with table salt.
  • Other: Placebo
    • 10 days of enteric capsules filled with dextrose.

Arms, Groups and Cohorts

  • Experimental: High Sodium
    • Consumption of an extra 3900 mg of dietary sodium per day.
  • Placebo Comparator: Placebo
    • Control Condition

Clinical Trial Outcome Measures

Primary Measures

  • Reflected Pulse Wave Amplitude
    • Time Frame: On the 10th day of each arm.
    • Aortic pressure-flow relations will be assessed non-invasively using echocardiography and peripheral artery applanation tonometry. Wave separation analysis will be used to calculate reflected pulse wave amplitude.
  • Conduit artery endothelium-dependent dilation
    • Time Frame: On the 10th day of each arm.
    • Brachial artery flow mediated dilation (FMD) will be assessed by duplex ultrasound as an index of conduit artery endothelial function.
  • Arterial Stiffness
    • Time Frame: On the 10th day of each arm.
    • Carotid-femoral pulse wave velocity (cf-PWV) will be assessed via applanation tonometry as an index of aortic stiffness. cf-PWV will be calculated as the difference in timing of of pulse waves at the carotid and femoral arteries divided by the distance between measurements.

Secondary Measures

  • Wave reflection timing
    • Time Frame: On the 10th day of each arm.
    • Aortic pressure-flow relations will be assessed non-invasively using echocardiography and peripheral artery applanation tonometry. Wave separation analysis will be used to calculate reflected wave transit time.
  • Forward Pulse Wave Amplitude
    • Time Frame: On the 10th day of each arm.
    • Aortic pressure-flow relations will be assessed non-invasively using echocardiography and peripheral artery applanation tonometry. Wave separation analysis will be used to the amplitude of the forward traveling pulse wave.
  • 24 Hour Blood Pressure
    • Time Frame: The morning of day 9 through the morning of day 10 for each arm.
    • 24 hour blood pressure monitoring will be performed using an ambulatory blood pressure monitor device. Average day and nighttime systolic, diastolic, and mean blood pressures will be determined.

Participating in This Clinical Trial

Inclusion Criteria

  • Healthy individuals (age 21-45) who are either sedentary (1 or less days of exercise per week during past year) or habitually active (4 or more days of aerobic exercise per week for a minimum of 1 year)

Exclusion Criteria

  • Body mass index <18 or >35
  • Systolic blood pressure ≥140 mmHg and/or diastolic blood pressure ≥90
  • Blood donation within past 8 weeks,
  • Glucose 6 phosphate dehydrogenase (G6PD) deficiency
  • A history of cancer, diabetes, or any other chronic disease
  • A history of any heart disease
  • A history of hormone therapy
  • Use of nicotine products
  • Pregnancy
  • Nursing mothers
  • Participation in regular physical activity greater than 1 day/week- but less than 4 days/week

Gender Eligibility: All

Minimum Age: 21 Years

Maximum Age: 45 Years

Are Healthy Volunteers Accepted: Accepts Healthy Volunteers

Investigator Details

  • Lead Sponsor
    • University of Delaware
  • Provider of Information About this Clinical Study
    • Sponsor
  • Overall Official(s)
    • David G Edwards, PhD, Principal Investigator, University of Delaware
  • Overall Contact(s)
    • David G Edwards, PhD, 302-831-3363, dge@udel.edu

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