Dietary Salt and Microvascular Function

Study Overview
=================
Brief Summary
-----------------
It is well accepted that high-salt (HS) intake is an essential risk factor in development and progression of hypertension. Results of some recent studies suggest that some of the deleterious effects of a HS diet are independent of elevated blood pressure (BP) and may occur in normotensive individuals and are associated with impaired endothelial function. However, the effects of acute salt loading on endothelial function and vascular reactivity in young healthy individuals are still scarce and inconsistent. The purpose of present study is to determine whether one week of HS intake affects microvascular reactivity in young healthy subjects without changes in BP. In addition, the investigators sought to evaluate if potential HS diet-induced microvascular dysfunction is associated with changes in oxidative stress level and/or with modification of immunological response in young healthy subjects.

Official Title
-----------------
Influence of High Salt Diet on Microvascular Reactivity in Young Healthy Subjects

Conditions
-----------------
Salt; Excess

Intervention / Treatment
-----------------
* Other: Low Salt (LS) diet
* Other: High Salt (HS) diet


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: - healthy volunteers Exclusion Criteria: oral contraceptives drugs that could affect the endothelium hypertension coronary artery disease diabetes hyperlipidaemia renal impairment cerebrovascular and peripheral artery disease

Ages Eligible for Study
-----------------
Minimum Age: 18 Years
Maximum Age: 25 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
Accepts Healthy Volunteers

Study Plan
=================
How is the study designed?
-----------------

Design Details

Primary Purpose: Basic Science
Allocation: Non-Randomized
Intervention Model: Crossover Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: low salt diet<br>All subjects will be instructed to maintain a low-sodium (LS) diet, with an intake of less than 2.3 g of salt per day (DASH eating plan; US Department of Health and Human Services, 2006) for 7 days (washout period). | Other: Low Salt (LS) diet<br>* Intake of less than 2.3 g of salt per day for 7 days.<br>|
| Experimental: high salt diet<br>After washout period, all subjects will be instructed to maintain a high-sodium (HS) diet, with an intake of 11.2 g of salt per day for 7 days. | Other: High Salt (HS) diet<br>* Intake of 11.2 g of salt per day for 7 days.<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| microvascular reactivity | Cutaneous microvascular blood flow will be measured by Laser Doppler Flowmetry in response to vascular occlusion (post occlusive reactive hyperemia- PORH) and in response to iontophoresis of acetylcholine (ACh) (endothelium dependent vasodilation) before and after diet protocols. | two weeks after starting the protocol | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| oxidative stress | As direct indicator of oxidative stress, byproducts of lipid peroxidation - TBARS method (Thiobarbituric Acid Reactive Substances) with malondialdehyde (MDA) as standard (µM MDA) will be measured before and after LS and HS diet protocol (spectrophotometric method). | two weeks after starting the protocol | 
| modification of immunological response by high salt diet | Activated monocytes/macrophages and neutrophils will be measured by flow cytometry, with distinction of subpopulation of monocytes/macrophages (classical/nonclassical), their activation and the expression of the integrin LFA-1 (lymphocyte function-associated antigen 1) and VLA-4 (Very Late Antigen-4) - ligands VCAM-1 (vascular cell adhesion molecule 1 ) and ICAM-1 (vascular cell adhesion molecule 1). | two weeks after starting the protocol | 
| antioxidant capacity | As an indicator of antioxidant capacity, the ferric reducing ability of plasma - the FRAP assay (Ferric reducing ability of plasma) with Trolox used as standard (mM Trolox) will be measured before and after LS and HS diet protocol (spectrophotometric method). | two weeks after starting the protocol | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
microvascular function, laser Doppler flowmetry, high salt diet