Visit 2 (day 2) is a next study assessment: 24-h blood pressure monitor is removed, after the overnight fast oral saline load is going to be given in a form of a standardized meal (soup) in a amount of 12 g of NaCl (average daily intake of salt in Croatia). The soup is going to be consumed in 30 minutes. Volunteers are going to be instructed to drink afterwards 1/2 L of water during next 1 h. Placebo in a form iv infusion of hypertonic saline is going to be given at a rate of 0.06 ml/kg/in and infused during 3 hours from beginning of oral sodium load. During 6 hours (from oral sodium load) urine is gong to be collected. Finally, blood samples are going to be drawn for glucose, insulin, sodium, potassium, serum osmolality, serum creatinine, renin activity, and aldosterone, BNP, ADH and GLP1 level after 3 and 6 hours. Sodium, chloride and calcium excretion, osmolality and creatinine are going to be measured in the urine after 3 hours. Patients are instructed to come again after 7 days fasting.