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

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

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.

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.

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