HIGH PLASMA ENDOTHELIN-1 LEVELS IN HYPERTENSIVE PATIENTS WITH LOW-RENIN ESSENTIAL-HYPERTENSION

Endothelin-1 (ET-1) is a potent vasoconstrictor peptide derived from e ndothelial cells and may be important in the control of systemic blood pressure (BP) and local brood flow. Immunoreactive ET-1 plasma levels may be normal or elevated in human arterial hypertension, although th e exact pathophysiological role of ET-1 remains to be established. The aim of our study was to determine the relationship between the compon ents of the renin-angiotensin-aldosterone system and plasma ET-1 level s in patients with law, normal or high-renin essential hypertension. T he study groups included 13 patients with low-renin essential hyperten sion (average age 43.5 +/- 16.2 years), 16 patients with normal-renin essential hypertension (46.5 +/- 13.4 years), 11 patients with high-re nin essential hypertension (40.7 +/- 13.8 years) and 12 healthy subjec ts (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 p g/ml; there was not a statistical correlation between plasma renin act ivity (PRA) and the ET-1 levels of hypertensives; instead there was a statistically significant correlation between plasma ET-1 and plasma a ldosterone (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 thos e of normotensive subjects (7.7 +/- 1.7 pg/ml), patients with normal-r enin essential hypertension (8.5 +/- 2.8 pg/ml), and patients with hig h-renin essential hypertension (9.9 +/- 3.8 pg/ml), respectively. Ther e was a statistical correlation between PA and ET-1 levels in patients with low-renin essential hypertension (r = 0.619, P < 0.024). Our stu dy demonstrated that there was an increase of circulating ET-1 revels in patients with low-renin essential hypertension and ET-1 plasma leve ls correlated with PA. The results suggest that ET-1 may play an impor tant role in this particular form of human essential hypertension.