Adverse Neurogenic Actions of Dietary Salt

University of Delaware

Status: Completed

Conditions: Blood Pressure

Treatments: Other: Medium Sodium Diet; Other: High Sodium Diet; Other: Low Sodium Diet

Study type: Interventional

Funder types: Other

Identifiers

NCT02881515

819183

Details and patient eligibility

About

Excess dietary salt increases the risk for cardiovascular events, even in people that are not hypertensive. There is some evidence that excess dietary salt exaggerates blood pressure and sympathetic nervous system responses to various perturbations and increases blood pressure variability. This proposal will examine the effects of low, medium, and high salt diets on cardiovascular reactivity and blood pressure variability.

Full description

Excess dietary salt causes target organ damage and increases the risk for adverse cardiovascular (CV) events independent of blood pressure (BP). Recent data in salt-resistant, normotensive rodents suggest that high dietary salt enhances the excitability or gain of sympathetic circuits, exaggerates sympathetic and CV responses to various stimuli, and increases BP variability (BPV). There are limited data regarding the impact of dietary salt intake on sympathetic nerve activity (SNA) and CV function in salt-resistant humans as well as the underlying mechanisms contributing to these adverse effects. The long-term goal is to determine how dietary salt adversely affects BP regulation and CV health. The objective of this proposal is to comprehensively evaluate the impact of dietary salt intake on SNA and CV reactivity and BPV in normotensive humans. The investigators have 2 specific aims: 1) Aim 1 will test the hypothesis that high dietary salt increases SNA and CV reactivity in normotensive adults, 2) Aim 2 will test the hypothesis that high dietary salt increases BPV in normotensive adults. The expected outcome is to demonstrate that dietary salt loading increases CV reactivity and BPV through a sympathetic nervous system mechanism that originates in the brain. The proposed research is significant, as these studies will provide empirical evidence that dietary salt intake impacts neurohumoral control of the circulation in salt-resistant humans. The proposed research is innovative because it will identify a novel neurogenic action of dietary salt in human CV regulation.

Enrollment: 77 patients

Sex: All

Ages: 21 to 75 years old

Volunteers: Accepts Healthy Volunteers

Inclusion criteria

• normal blood pressure
• men, Women, minorities
• ECG within normal limits
• screening blood panel within normal limits

Exclusion criteria

• high blood pressure (>140/90 mmHg)
• history of cardiovascular disease
• history of cancer
• history of diabetes
• history of kidney disease
• obesity (BMI > 30 kg/m2)
• smoking or tobacco use
• current pregnancy
• nursing mothers
• communication barriers

Trial design

Primary purpose: Basic Science

Allocation: Randomized

Interventional model: Crossover Assignment

Masking: Single Blind

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77 participants in 2 patient groups

Blood Pressure Reactivity

Experimental group

Description:

Blood Pressure Responses to a cold pressor test and acute exercise will be assessed. This will be performed while subjects are on a low sodium diet (1000 mg/daily), medium sodium diet (2300 mg/daily), and high sodium diet (7000 mg/daily).

Treatment:

Other: High Sodium Diet

Other: Medium Sodium Diet

Other: Low Sodium Diet

Blood Pressure Variability

Experimental group

Description:

Twenty four hour blood pressure variability will be assessed. This will be performed while subjects are on a low sodium diet (1000 mg/daily), medium sodium diet (2300 mg/daily), and high sodium diet (7000 mg/daily).

Treatment:

Other: High Sodium Diet

Other: Medium Sodium Diet

Other: Low Sodium Diet