[125I]-ET=1 Binding to Perivascular Nerves of Human Epicardial Coronary Arteries

In vitro autoradiographic studies, using sections of human epicardial coronary arteries, have demonstrated dense [125I]-endothelin-l binding to the tunica media and regions of the adventitia. Micro-autoradiography has been employed to localise binding at the cellular level and immunohistochemistry has been used to identify specific cell types on adjacent tissue sections. Adventitial [125I]-ET-1 binding is predominantly to microvessels, including those supplying the perivascular nerves. This binding is markedly reduced in the presence of unlabelled ET-1 and the ETA/ETB receptor antagonist bosentan. These results suggest that, apart from acting on vascular smooth muscle of the tunica media, the action of locally-released ET-1 may also be via adventitial microvessels, including those supplying the perivascular nerves.