The cardiovascular and bronchoconstrictor actions of endothelin-1 (ET-1) in the anesthetized guinea pig and the cardiovascular effects and gastric ulcerogenic actions in the anesthetized rat were investigated. In the guinea pig, ET-1 (0.05-1 nmol/kg i.v.) induced a dose-related increase in pulmonary inflation pressure, which was substantially inhibited by pretreatment with indomethacin and the thromboxane receptor antagonist BM 13.177. The concurrent vasopressor effects of ET-1 were attenuated but not abolished by these agents. In the rat, ET-1 (0.1-0.4 nmol/kg i.v.) induced a biphasic effect on arterial blood pressure (BP), with a transient fall being followed by a rise, which was unaffected by indomethacin pretreatment, whereas i.v. infusion of ET-1 induced only an increase in BP. Local intra-arterial infusion of ET-1 (0.04-0.1 nmol/kg/min) induced extensive macroscopically determined gastric mucosal damage in the rat, confirmed histologically. Thus, the pharmacological profile of ET-1 encompasses bronchoconstriction, vasopressor and vasodepressor actions, as well as potent gastric ulcerogenic properties.