Endothelin is a potent constrictor of human intracranial arteries and veins.

Endothelin, a peptide produced in endothelial cells, was found to be a potent constrictor of human pial arteries through a direct, slow action on the smooth muscle cell, with a pD2 value of 8.54. It was less potent as a constrictor in pial veins (pD2 7.80) and in branches of the middle meningeal artery and superficial temporal artery (pD2 7.61 and 7.77). The major component of the contractile response in the arteries comprises an effect on potential-operated calcium channels, as evidenced by tests with nimodipine. Endothelin may regulate intracranial vessels tonically during physiological as well as pathophysiological conditions.