[High circulating levels of adrenomedullin and endothelin-1 in obesity associated with arterial hypertension]

Abstract

Background: The aim of the study was to investigate the behavior of two endothelial vasoactive peptides, adrenomedullin (vasodilator) and endothelin-1 (vasoconstrictor), in human obesity with and without arterial hypertension.

Methods: The study was carried out on 30 obese subjects (body mass index > 27 kg/m2) divided into two groups: 15 normotensive obese patients (10 males, 5 females, mean age 42 +/- 12 years) and 15 hypertensive obese patients (9 males, 6 females, mean age 42 +/- 13 years). The control group consisted of 21 normal subjects (12 males, 9 females, mean age 38 +/- 12 years) and of 16 patients with essential hypertension (10 males, 6 females, mean age 41 +/- 12 years) but without organ damage. All studied subjects were taking a normocaloric (20-22 kcal/kg/day), normosodic (120-140 mEq/day) and normopotassic (50-60 mEq/day) diet. Between 8.00 and 9.00 a.m., a venous blood sample was taken for the determination (radioimmunoassay) of plasma adrenomedullin and endothelin-1 concentrations.

Results: Plasma adrenomedullin levels in normal subjects (13.7 +/- 6.1 pg/ml) were similar to those in normotensive obese patients (14.8 +/- 7.2 pg/ml), whereas in hypertensive obese patients (22.5 +/- 9.1 pg/ml) and in those with essential hypertension (22.7 +/- 8.2 pg/ml) levels were significantly higher (ANOVA = 0.000, p < 0.05) than those of normal subjects and of normotensive obese patients. Moreover, endothelin-1 plasma concentrations were found to be significantly higher (ANOVA = 0.000, p < 0.05) in hypertensive obese patients (10.3 +/- 2.7 pg/ml) compared to normal subjects (6.5 +/- 2.4 pg/ml), normotensive obese patients (8.3 +/- 1.5 pg/ml) and to those with essential hypertension (8.5 +/- 2.9 pg/ml). In patients with essential hypertension, a positive correlation (r = 0.493, p < 0.05) was found between adrenomedullin and endothelin-1 plasma levels.

Conclusions: These results revealed that in human obesity associated with arterial hypertension there is an increased production of plasma adrenomedullin and endothelin-1 that, with their opposite vasoactive properties (vasodilation/vasoconstriction), can contribute to this pathological association.