Iloprost antagonizes endothelin-induced vasoconstriction in macro- and microcirculation.

In conscious Wistar rats, endothelin (ET-I) caused a dose-dependent long-lasting blood pressure increase, which was more pronounced after indomethacin pretreatment. The initial blood pressure drop was also enhanced after indomethacin. The stable prostacyclin analogue iloprost completely reversed the pressor effect of endothelin. In the hamster cheek pouch, ET-I caused a rapidly developing, long-lasting constriction of arterioles, which could be completely reversed by iloprost. The results demonstrate that prostacyclin can act as a potent functional antagonist of endothelin-induced systemic and local pressor responses.