Inhibition of prostanoid-mediated contraction to endothelin-1 after hypoxia in rat aorta

The role of the thromboxane A(2)/prostaglandin H, receptor in endothelin-1 contraction was investigated in aortic rings from rats exposed to normoxia (21% O-2) or hypoxia (10% O-2) for 12 h. Indomethacin (10 muM) and SQ 29,54 8 (0.1 muM, thromboxane A(2)/prostaglandin H-2 receptor antagonist) reduced maximum tension and increased EC50 in endothelium-intact and -denuded ring s from normoxic animals. Neither inhibitor had any effect on rings from hyp oxic rats. Thromboxane A(2) and/or prostaglandin Hz contribute to the respo nse to endothelin-l in aortas from normoxic rats but not from rats exposed to hypoxia. Loss of prostanoid-enhancement of endothelin-1 contraction cont ributes to impair vascular reactivity after hypoxia. (C) 2001 Elsevier Scie nce B.V. All rights reserved.