Pressor effects of circulating endothelin are limited by its removal in the pulmonary circulation and by the release of prostacyclin and endothelium-derived relaxing factor.

Abstract

Endothelin releases prostacyclin and thromboxane A2 from guinea pig or rat isolated lungs and endothelium-derived relaxing factor in the perfused mesentery of the rat. Endothelin is also substantially removed by the pulmonary circulation of the rat in vitro and in vivo and by guinea pig lungs in vitro. In the rat, the effects of endothelin on the blood pressure vary from pressor (in pithed rats) to purely depressor in anesthetized rats where the resting blood pressure is high. It therefore has the characteristics of a local pressor hormone, rather than a circulating one.