EDN1 and Huntington disease: However, the maximal contractile response to ET-1 (P<0.01, Fig. 1A), U46619 (P<0.0001, Fig. 2A), Ang II (P<0.01, Fig. 2C) and vasopressin (P<0.0001, Fig. 2E) were all significantly enhanced in arteries from HD patients.