Different Effects of Endothelin-1 on cAMP-and cGMP-Mediated Vascular Relaxation in Human Arteries and Veins

Endothelin-1 (ET-1) is a new cardiovascular hormone produced by endothelial cells. The vascular effects of the peptide and its interaction with cAMP-and cGMP-dependent relaxation were investigated in human arteries and veins. Internal mammary arteries and veins and saphenous veins were obtained intraoperatively and suspended in organ chambers; isometric tension was recorded. The blood vessels were contracted with ET-1 or norepinephrine and relaxations to prostacyclin or sodium nitroprusside were studied. Mammary veins exhibited an enhanced sensitivity to ET-1 (10–1 to 3 $$ 10–7M) as compared to the artery and saphenous vein (log shift at ED50: 32-and 79-fold, respectively; p