Venous smooth muscle contains vasoconstrictor ETB-like receptors

Abstract Two endothelin (ET) receptor subtypes have been identified to date: the ET A receptor which preferentially binds ET-1 over ET-3, and the ET B receptor which is non-selective. This study characterized the ET receptor subtypes present in several vascular smooth muscle preparations using standard in vitro techniques. In all but one of the arteries tested, ET-3 was significantly less potent than ET-1. In contrast, the potency of ET-3 was very similar to that of ET-1 in all of the veins. The selective ET A receptor antagonist BQ-123 blunted the ET-1 contractions in rabbit carotid artery, but not in saphenous vein. The selective ET B receptor ligand sarafotoxin S6c contracted the rabbit saphenous vein, but not the carotid artery. These data suggest that vascular smooth muscle cells express ET A and ET B receptors. Stimulation of either receptor subtype can result in force development.