RETRACTED: AN ENDOTHELIN-B RECEPTOR-SELECTIVE ANTAGONIST - IRL-1038, [CYS(11)-CYS(15)]-ENDOTHELIN-1(11-21) (RETRACTED ARTICLE. SEE VOL 342, PG 103, 1994)

In the inhibition of specific binding of [I-125]endothelins (ETs) to membranes from various tissues of rats, guinea pigs, pigs and humans, [Cys11-Cys15]-Et-1(11-21), IRL 1038, has a much higher affinity for ET(B) receptors (K(i) = 6-11 nM) than for ET(A) receptors (K(i) = 0.4-0.7 muM). In contraction assays, with ET-3 as a stimulant, 3 muM IRL 1038 antagonized the ET(B) receptor-mediated contraction of guinea pig ileal and tracheal smooth muscle without any significant agonistic activity, but did not effect the ET(A) receptor-mediated contraction of rat aortic smooth muscle. IRL 1038 is, therefore, considered to be the first antagonist selective to the ET(B) receptor.