[125I]-Endothelin-1 Binding to Vasa Vasorum and Regions of Neovascularization in Human and Porcine Blood Vessels: A Possible Role for Endothelin in Intimal Hyperplasia and Atherosclerosis

The distribution of [I]-endothelin-1 (ET-1) binding sites on human and porcine vessels was studied with in vitro receptor autoradiography. Binding to normal human saphenous veins was compared to atheromatous veins used as coronary artery bypass grafts. Binding to porcine vessels, from an experimental model of intimal hyperplasia, was also studied. There was dense binding of [I]-ET-1 to smooth muscle of all vessels examined, as well as to the vasa vasorum and regions of neovascularization of diseased vessels. Binding to microvasculature (vasa vasorum and regions of neovascularization) is of particular interest, because ET-1 has been shown to have mitogenic activity on vascular smooth-muscle cells in culture and microvessels are extremely sensitive to the constrictor effect of ET-1. Binding of [I]-ET-1 to vasa vasorum of normal blood vessels and to regions of neovascularization of atheromatous vessels suggests that ET-1 plays a pathophysiologic role in atherosclerosis.