The Effect of High and Low Sodium Intake on Urinary Aquaporin-2 in Healthy Humans.

Inclusion Criteria: * Caucasic men and women * Age 18-65 years * Body mass index less or equal to 30 Kg/m2 Exclusion Criteria: * Arterial hypertension * History or clinical signs of heart, brain, lung, kidney, malignant or endocrine organ disease. * Abnormal biochemical screening of the blood regarding: red and white cell count, B-hemoglobin, P-sodium, P-potassium, P-creatinine, P-albumine, P- bilirubin, P-alanine aminotransferase, P- alkaline phosphatase, p-cholesterol and B-glucose. * Abnormal screening of the urine regarding: blood, albumine and glucose. * Alcohol or drug abuse * Drug use except oral contraceptives * Smoking * Abnormal electrocardiogram * Blood donation within one month of the first examination day * Pregnancy * Unwillingness to participate