Human saphenous vein contains both endothelin ET A and ET B contractile receptors

Abstract

We have investigated the endothelin receptor subtypes mediating contraction in isolated preparations of human saphenous vein. Endothelin-1 (EC 50: 17.8 nM), endothelin-3 (EC 50: 82.3 nM) and the endothelin ET B receptor-selective agonists, [Ala 1,3,11,15]endothelin-1 (EC 50: 63 nM) and sarafotoxin S6c (EC 50: 0.75 nM) all produced concentration-dependent contractions of human saphenous vein, although [Ala 1,3,11,15]endothelin-1 and sarafotoxin S6c only produced a contraction in ∼50% of the preparations tested. The endothelin ET A receptor antagonist, BQ123 ( D-Val,Leu, D-Trp, D-Asp,Pro; 10 μM), antagonized endothelin-1-induced contractions with an estimated potency (p K B ∼ 6.0) which was an order of magnitude lower than reported previously for non-human isolated vascular tissues from other species (pA 2 values ∼ 7.0). These data suggest that both endothelin ET A and endothelin ET B receptors can mediate vascular smooth muscle contraction in human saphenous vein.