The aim of this study was to define the types of endothelin receptors present in the canine tibial vasculature. Endothelin receptor agonists and antagonists were used in two different models: isolated nutrient tibial arteries in organ bath and in vitro-perfused canine tibial bones. In isolated nutrient tibial arteries, endothelin-1 caused concentration-dependent contractions of rings with and without endothelium. BQ-123, a selective endothelin-A antagonist, induced a significant rightward shift of endothelin-1 concentration-response curves. No contractions were observed with sarafotoxin S6c, a selective endothelin-B agonist. The responses of endothelin-1 were not affected by the presence of NG-monomethyl-L-arginine acetate plus indomethacin or by removal of the endothelium. In perfused tibial bones, endothelin-1 was more potent than endothelin-3 in causing concentration-dependent contractions. Neither endothelin-1, endothelin-3, nor sarafotoxin S6c caused relaxations. Neither the inhibition of nitric oxide nor the inhibition of prostaglandins significantly altered contractions to endothelin-1. These concordant data indicate that endothelin is a vasoconstrictor in the bone vasculature, an effect that appears to be mediated only through endothelin-A receptors.
ASJC Scopus subject areas
- Orthopedics and Sports Medicine