Tissue selectivity of endothelin.

The effects of endothelin, a potent endogenous vasoconstrictor peptide, were examined in a range of vascular and non-vascular tissues. At concentrations that cause vasoconstriction in portal vein and aorta, the peptide strongly contracted rat uterus, trachea and vas deferens, but not guinea pig ileum. Nifedipine, a dihydropyridine calcium anatgonist, partially inhibited these contractions. Endothelin had no inotropic or chronotropic effect on the isolated rat heart. The peptide did not modulate secretion at the neuromuscular junction, from adrenal medullary cells or neutrophils, nor affect secretion or aggregation of platelets. The tissue responsiveness to endothelin was not the same as the tissue distribution of dihydropyridine receptors. This supports the idea that endothelin interacts with a specific receptor distinct from dihydropyridine sensitive calcium channels. The contractile effect of endothelin on non vascular smooth muscle suggests that the concept of endothelium dependent modulation of vascular smooth muscle tone may be extended to include epithelium dependent modulation of non vascular tissues.