Hypertension in black patients - An emerging role of the endothelin systemin salt-sensitive hypertension

The prevalence of essential hypertension in blacks is much higher than that in whites. In addition, the pathogenesis of hypertension appears to be dif ferent in black patients. For example, black patients present with a salt-s ensitive hypertension characterized by low renin levels. Racial differences in renal physiology and socioeconomic factors have been suggested as possi ble causes of this difference, but reasons for this difference remain uncle ar. Endothelial cells an important in the regulation of vascular tonus and homeostasis, in part through the secretion of vasoactive substances. One of these factors, endothelin-1 (ET-1), is a 21 amino acid residue peptide wit h potent vasopressor actions. In addition to its contractile effects, it ha s been shown to stimulate mitogenesis in a number of cell types. Moreover, ET-1 displays modulatory effects on the endocrine system, including stimula tion of an angiotensin II and aldosterone production and inhibition of anti diuretic hormone in the kidney. Recent data from several laboratories indic ate that ET-1 is overexpressed in the vasculature in several salt-sensitive models of experimental hypertension. Moreover, circulating plasma ET-1 lev els are significantly increased in black hypertensives compared with white hypertensives. Thus, the ET system might be particularly important in the d evelopment or maintenance of hypertension in this population.