High plasma endothelin-1 levels in hypertensive patients with low-renin essential hypertension

Abstract

Endothelin-1 (ET-1) is a potent vasoconstrictor peptide derived from endothelial cells and may be important in the control of systemic blood pressure (BP) and local blood flow. Immunoreactive ET-1 plasma levels may be normal or elevated in human arterial hypertension, although the exact pathophysiological role of ET-1 remains to be established.The aim of our study was to determine the relationship between the components of the renin-angiotensin-aldosterone system and plasma ET-1 levels in patients with low, normal or high-renin essential hypertension.The study groups included 13 patients with low-renin essential hypertension (average age 43.5 ± 16.2 years), 16 patients with normal-renin essential hypertension (46.5 ± 13.4 years), 11 patients with high-renin essential hypertension (40.7 ± 13.8 years) and 12 healthy subjects (43.1 ± 11.4 years).Our results demonstrated that the mean ET-1 values of all patients with essential hypertension were 10.4 ± 3.4 pg/ml; there was not a statistical correlation between plasma renin activity (PRA) and the ET-1 levels of hypertensives; instead there was a statistically significant correlation between plasma ET-1 and plasma aldosterone (PA) (r = 0.393; P < 0.026). in particular mean plasma et-1 values in patients with low-renin essential hypertension (12.6 ± 2.1 pg/ml) were significantly higher (anova = 0.000, P < 0.05) than those of normotensive subjects (7.7 ± 1.7 pg/ml), patients with normal-renin essential hypertension (8.5 ± 2.8 pg/ml), and patients with high-renin essential hypertension (9.9 ± 3.8 pg/ml), respectively. there was a statistical correlation between pa and et-1 levels in patients with low-renin essential hypertension (r = 0.619, P < 0.024).Our study demonstrated that there was an increase of circulating ET-1 levels in patients with low-renin essential hypertension and ET-1 plasma levels correlated with PA. The results suggest that ET-1 may play an important role in this particular form of human essential hypertension.