Two functional endothelin receptors in guinea-pig pulmonary arteries.
The contractile effects of endothelins (ET-1, ET-2, ET-3) were investigated in pulmonary vessels and trachea from the guinea-pig using a sensitive in vitro method. ET-1 and ET-2 were potent agonists that concentration-dependently contracted pulmonary vessels. ET-3 was also an agonist but was less potent. In contrast, ET-1, ET-2 and ET-3 showed equal potencies in inducing contractions of tracheal segments. Using a pharmacological desensitization technique, evidence was provided for two types of functional endothelin receptors. Putatively, ET-1 and ET-2 act on the same functional receptor in the pulmonary artery whereas ET-3 acts on another receptor. Intraregional differences of the responses to endothelins were noticed when small intrapulmonar resistance arteries were compared to large proximal arteries. These differences are probably due to variations in the distribution of endothelin receptors rather than to receptor heterogeneity.
Cardell
L O
LO
Department of Otorhinolaryngology, Malmö General Hospital, Malmö, Sweden.
Uddman
R
R
Edvinsson
L
L