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.
Study Type
INTERVENTIONAL
Allocation
NON_RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
10
High salt diet (250 mmol/day) in 5 days followed by low salt diet (60-70 mmol/day) in 5 days.
Low salt diet (60-70 mmol/day) in 5 days followed by high salt diet (250 mmol/day) in 5 days.
University of Southern Denmark
Odense, Denmark
Changes in epithelial sodium channel (ENaC) appearance in urinary exosomes
Semiquantitative western blotting
Time frame: After 5 days on high or low salt diet
Plasma aldosterone
Concentration in plasma.
Time frame: Before study start and after 5 days on high or low salt diet
Renin
Concentration in plasma.
Time frame: Before study start and after 5 days on high or low salt diet
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