THE VASOCONSTRICTOR ACTION OF BIG ENDOTHELIN-1 IS PHOSPHORAMIDON-SENSITIVE IN RABBIT SAPHENOUS ARTERY, BUT NOT IN SAPHENOUS-VEIN

The effects of big endothelin-1 and endothelin-1 on vascular reactivity were compared in isolated rabbit saphenous artery and vein. The contractile potency of endothelin-1 was three times higher in the vein than in the artery. In contrast, big endothelin-I was two times more effective in the artery. Phosphoramidon (100 muM), a metalloproteinase inhibitor, antagonised the contractile action of big endothelin-I in the artery but not in the vein. These data suggest that the biosynthetic pathway leading to the formation of endothelin differs in arterial and venous vessels.