PATHOPHYSIOLOGICAL ROLE OF ENDOTHELIN REVEALED BY THE 1ST ORALLY-ACTIVE ENDOTHELIN RECEPTOR ANTAGONIST

SINCE its discovery1, endothelin-1 has attracted considerable scientif ic interest because of its extremely potent and long-lasting vaso-cons trictor effect and its binding to G-protein-coupled receptors2. Plasma concentrations of endothelin-1 are low3 and its release by endothelia l cells is polarized towards the basolateral side4,5, suggesting that it is a paracrine factor and not a hormone. Consequently, the effect o f injected endothelin-1 may not reflect the effect of endogenous endot helin-1. In contrast, blockade of the action of endogenous endothelin- 1 using receptor antagonists should be a valuable means of investigati ng its physiological and pathological effects. We report here evidence for the pathophysiological role of endothelin-1 as brought by the fir st synthetic orally active non-peptide antagonist of endothelin recept ors, Ro 46-2005.