Background: Both leptin and the renin-angiotensin system (RAS) are involved in the regulation of arterial blood pressure. This study was undertaken to assess the relationship between RAS and plasma leptin concentration in hypertensive patients under conditions of normal and restricted sodium supply and upright position.
Material/Methods: In 31 patients with essential hypertension (EHP – 14 F, 17 M, age 44±14 years, BMI 29.3±6.4 kg/m2) and 8 healthy subjects (NHS - 4 F, 4 M, age 37(17 years, BMI 25.3±6.6 kg/m2) plasma leptin concentration, plasma renin activity (PRA), and 24-hour urinary sodium excretion (UNa) were evaluated twice: first on a diet containing 100–120 mmol sodium per day and after 8 hours overnight bed rest, and a second time after 3 days of dietary sodium restriction (10–20 mmol daily) and 3 hours in upright position.
Results: Dietary sodium restriction and upright position was followed by a significant increase in PRA and decrease of UNa. By contrast, plasma leptin concentration showed a moderate decrease both in EHP and NHS. No significant correlation was found between PRA and plasma leptin concentrations in either of the groups examined.
Conclusion: From the results obtained in this study we may conclude that dietary sodium restriction and upright position exerts only a moderate effect on plasma leptin concentration, in contrast to PRA, in both hypertensive and normotensive subjects.

Keywords: essential hypertension, plasma renin activity, dietary sodium, Leptin