Relaxation of human temporal artery by endothelin ET(B) receptors

Endothelin receptors have been characterized in human temporal artery by molecular biological methods and in vitro pharmacology. Reverse transcriptase-polymerase chain reaction was used to detect mRNA encoding ET(A) and ET(B) receptors in normal and endothelium-denuded arteries. Vasomotor response experiments with a specific ET(A) antagonist (FR 139317) suggested the presence of ET(A) subtypes. Marked ET(B)-mediated relaxation was obtained with ET-3 when ET(A) activity was blocked in precontracted arteries. Relaxation was significantly reduced by bosentan, indomethacin, and a nitric oxide synthase inhibitor. It may be speculated that the relaxant activity is mediated through ET(B1) receptors. Copyright (C) 1996 Elsevier Science Inc.