The kidney is both a source of endothelin (ET) generation and an important
target organ of this peptide. The highest concentrations of ET-1 in the bod
y exist in the renal medulla, where it mediates natriuretic and diuretic ef
fects through the ETB receptor subtype. It is proposed that aberrations in
the renal ET system may lead to sodium and water retention and subsequently
to the development of hypertension.