The Influence of High and Low Salt on Exosomes in the Urine

Study Overview
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Brief Summary
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The hypothesis is that changes in the epithelial sodium channel (ENaC) in the kidney is reflected in urinary exosomes and that the amount of ENaC as well as the cleavage degree is upregulated in conditions with low salt.

Detailed Description
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Methods: Exosomes will be isolated from spot urine by ultracentrifugation and tested using western blotting. In-house developed antibodies against different parts of the ENaC gamma subunit as well as commercial antibodies will be used. A marker for exosomes will validate the presence of exosomes in the urine. Power considerations: In this cross over salt-intervention study with quantification of ENaC the investigators refer to a published study regarding the sodium-chloride co-transporter (NCC) in the kidney, were rats where given aldosterone infusion or a low salt diet. In this study n=6 was sufficient to detect a 2-3 fold change in NCC in urinary exosomes. Furthermore 5 patients with primary aldosteronism had a significant increase in NCC in urinary exosomes (N. Lubbe et al, Hypertension 2012). On the basis of this the investigators choose to test 10 persons, but are not able to make a regular power calculation.

Official Title
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The Influence of High and Low Salt on Exosomes in the Urine

Conditions
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Healthy

Intervention / Treatment
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* Dietary Supplement: High salt diet followed by low salt diet
* Dietary Supplement: Low salt diet followed by high salt diet


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Healthy men aged 20-40 Body Mass Index (BMI, weight/height^2) between 18 and 25. Exclusion Criteria: Increased blood pressure (hypertension) or in treatment for high blood pressure Diabetes Regular medical intake Smoking Expectation of lacking cooperation or lack of understanding of the experiment Clinical relevant organic or systemic disease including malign disease Decreased kidney function

Ages Eligible for Study
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Minimum Age: 20 Years
Maximum Age: 40 Years

Sexes Eligible for Study
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Male

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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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: Healthy male test subjects 1-5<br>High salt diet followed by low salt diet | Dietary Supplement: High salt diet followed by low salt diet<br>* High salt diet (250 mmol/day) in 5 days followed by low salt diet (60-70 mmol/day) in 5 days.<br>|
| Experimental: Healthy male test subjects 6-10<br>Low salt diet followed by high salt diet | Dietary Supplement: Low salt diet followed by high salt diet<br>* Low salt diet (60-70 mmol/day) in 5 days followed by high salt diet (250 mmol/day) in 5 days.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Changes in epithelial sodium channel (ENaC) appearance in urinary exosomes | Semiquantitative western blotting | After 5 days on high or low salt diet | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Plasma aldosterone | Concentration in plasma. | Before study start and after 5 days on high or low salt diet | 
| Renin | Concentration in plasma. | Before study start and after 5 days on high or low salt diet | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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ENaC, Exosomes, Urinary biomarker, Salt regulation