Prostacyclin mediates antiaggregatory and hypotensive actions of endothelin in anaesthetized beagle dogs.

The effects of endothelin on blood pressure and in vivo aggregation of platelets were studied in anaesthetized beagle dogs. Intravenous administration of endothelin (0.03-0.3 nmol kg-1) resulted in a dose-dependent transient hypotension followed by a long-lasting hypertension and inhibition of platelet aggregation. These changes were accompanied by dose-dependent elevation of plasma 6-keto prostaglandin F1 alpha levels. Pretreatment of the animals with acetylsalicylic acid significantly attenuated both the vascular and antiaggregatory responses to endothelin. These data provide evidence for in vivo release of prostacyclin by endothelin in anaesthetized dogs.