PD156707: a potent antagonist of endothelin-1 in human diseased coronary arteries and vein grafts.

We have determined the ability of the endothelin A (ETA)-selective antagonist PD156707 to block constrictor ET-1 responses in blood vessels from the diseased human heart. ET-1 potently contracted nonatherosclerotic coronary arteries from patients with cardiomyopathy (pD2 = 7.96 +/- 0.15; n = 6), atherosclerotic coronary arteries from patients with ischemic heart disease (pD2 = 8.26 +/- 0.20; n = 4), and saphenous vein grafts that had developed "atherosclerotic" disease after coronary artery bypass (pD2 = 8.41 +/- 0.09; n = 6). PD156707 (100 nM) antagonized the vasoconstrictor response to ET-1 in each of the three preparations, with estimated pA2 values of 7.91 +/- 0.20, 8.05 +/- 0.14, and 8.07 +/- 0.02, respectively. These data suggest that the upregulation of ETB receptors that has been reported in human atherosclerotic coronary arteries does not contribute significantly to the ET-1-mediated constrictor response in these vessels in vitro.