Circulating levels of endothelin-1 in a homogenous Gulf Arab population with untreated essential hypertension

Abstract

Background: Racial variations are reported in the natural history of hypertension. For example, hypertension is significantly more prevalent in blacks than whites. Endothelial cells are important regulators of vas-cular tone and homeostasis, in part through secretions of vasoactive substances including endothelin-1 (ET-1), a small peptide with potentva-sopressor actions. In black hypertensives, ET-1 levels are higher than in normotensive blacks and in both hypertensive and normotensive whites. Since ET-1 might play a significant role in the development and severity of hypertension in the indigenous Arab population of the United Arab Emirates, we investigated the circulating levels of ET-1 in this homog-enous population. Patients and Methods: ET-1 levels were measured in plasma sam-ples from 60 untreated hypertensive Arabs and compared with 60 age-and sex-matched normotensive controls. Results: ET-1 levels were significantly higher in hypertensives (mean 10.1±1 pmol/L) than normotensives (mean 2.2±0.5 pmol/L). Body mass index (BMI) was slightly higher among the hypertensives. For all sub-jects these levels significantly (P< 0.001) correlated with systolic blood pressure and less significantly (P< 0.05) with diastolic blood pressure and body weight. The correlation between ET-1 and both systolic and diastolic blood pressure was persistently significant after adjusting for BMI. Conclusion: Plasma concentrations of ET-1 are significantly higher in hypertensive Gulf Arabs as compared with reported levels in white hy-pertensives and ET-1 could be a risk factor for cardiovascular diseases in this population. The endothelial system might be particularly impor-tant with respect to hypertension in this racial group and merits further study.