Relationship between plasma renin profile and leptinaemia in patients with essential hypertension

Both leptin and the renin-angiotensin system (RAS) can influence the activity of the sympathetic nervous system, water and electrolyte metabolism as well as vascular remodelling, which are all involved in the regulation of arterial blood pressure. Thus leptin and the RAS may act together in the pathogenesis of essential hypertension. The present study aimed to answer the following question: does an interrelationship exist between leptinaemia and the plasma renin activity (PRA) profile in normotensive and hypertensive subjects? Forty-three patients with essential hypertension (EHP) (23 females, 20 males, mean age 39.0 +/- 1.8 years, mean body mass index (BMI) 26. 8 +/- 0.6 kg/m2, mean arterial pressure (MAP) 123 +/- 2 mm Hg) and 32 healthy subjects (NTS) (18 females, 14 males, mean age 38.6 +/- 2. 2 years, mean BMI 25.4 +/- 0.5 kg/m2, MAP 95 +/- 1 mm Hg) were examined. Plasma leptin levels were estimated once after the administration of a diet containing 100-120 mmol Na/day and after overnight 8-h recumbency. PRA was estimated twice: first after the administration of a diet containing 100-120 mmol Na day and overnight 8-h recumbency (PRA I), and a second time after 3 days of sodium restriction (20 mmol Na/day), and 3 h of upright position (PRA II). Antihypertensive drugs were withdrawn 7 days before the study. In EHP plasma leptin concentration was insignificantly higher than in NTS (14.0 +/- 2.0 vs10.8 +/- 1.5 ng/ml respectively). Only females with hypertension showed a significant positive correlation between plasma leptin concentrations (expressed as the logarithmic values) and PRA I. Using the multiple regression analysis, in all studied subjects (EHP and NTS together), logarithm (log) of plasma leptin concentrations was significantly related to gender, BMI and MAP. Multiple regression analysis performed separately for EHP or NTS revealed a significant relation of log plasma leptin concentrations with gender and BMI. A significant correlation was found between log leptinaemia values and BMI, mean and systolic blood pressure respectively if the whole group of subjects (EHP+NTS) or EHP and NTS separately were analysed. Especially in hypertensive women a highly significant correlation was found between log plasma leptin concentrations and MAP. We conclude that a significant relationship between leptinaemia and PRA does exist in females with EH and that participation of both PRA and leptin in the pathogenesis of EH in females seems to be likely.