Blood Pressure
Conditions
Brief summary
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.
Detailed 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.
Interventions
OTHERLow Sodium Diet
Ten days of low sodium diet
OTHERMedium Sodium Diet
Ten days of a medium sodium diet
OTHERHigh Sodium Diet
Ten days of a high sodium diet
Sponsors
University of Delaware
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
BASIC_SCIENCE
Masking
SINGLE (Investigator)
Eligibility
Sex/Gender
ALL
Age
21 Years to 75 Years
Healthy volunteers
Yes
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
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Blood Pressure Variability | Day 10 of diet (i.e., after 10 days of low, medium, and high sodium diets; crossover design) | Standard deviation of systolic blood pressure over 24 hours (mmHg) |
| Blood Pressure Reactivity - Handgrip exercise | Day 10 of diet (i.e., after 10 days of low, medium, and high sodium diets; crossover design) | Change in Blood pressure during handgrip exercise (mmHg) |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Blood Pressure Reactivity - Cold Pressor test | Day 10 of diet (i.e., after 10 days of low, medium, and high sodium diets; crossover design) | Change in Blood pressure during a cold pressor test (mmHg) |
| Sympathetic Responses - Handgrip exercise | Day 10 of diet (i.e., after 10 days of low, medium, and high sodium diets; crossover design) | Sympathetic outflow (bursts per minute) |
| Sympathetic Responses - Cold Pressor test | Day 10 of diet (i.e., after 10 days of low, medium, and high sodium diets; crossover design) | Sympathetic outflow (bursts per minute) |
Countries
United States
Outcome results
None listed