Tryptaminergic receptors in the bovine pulmonary vasculature: effects of ketanserin.
The vasoconstrictor actions of 5-hydroxytryptamine (5-HT) were investigated in the isolated helical strips of the pulmonary artery and vein of the adult bovine and calf. Agonist-antagonist interactions were studied by pretreating the vessels with methysergide, ketanserin and phentolamine and then establishing the dose-response curves to 5-HT or noradrenaline (NA). Methysergide significantly (p less than 0.05) inhibited 5-HT-induced contractions in the vessels. Ketanserin antagonized the vasoconstrictor actions of 5-HT but inhibition was not dose-related. NA-induced contractions of the vessels from the adult bovine were non-competitively inhibited by ketanserin. Phentolamine (PH) competitively antagonized contractions induced by 5-HT and NE in the tissues. The results suggest that 1. ketanserin is a potent, competitive antagonist of 5-HT but a weak antagonist of NE and 2. 5-HT-induced contractions in the bovine pulmonary vessels are mediated via specific tryptamine receptors (5-HT2) and alpha-adrenergic receptors.
D000818:Animals; D002417:Cattle; D004305:Dose-Response Relationship, Drug; D005260:Female; D066298:In Vitro Techniques; D007650:Ketanserin; D008297:Male; D008784:Methysergide / Q000494:pharmacology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D010646:Phentolamine / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology*; D011651:Pulmonary Artery / Q000187:drug effects; D011667:Pulmonary Veins / Q000187:drug effects; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects; D011985:Receptors, Serotonin / Q000187:drug effects*; D012702:Serotonin Antagonists / Q000494:pharmacology*
D010880:Piperidines; D011942:Receptors, Adrenergic, alpha; D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; D007650:Ketanserin; D008784:Methysergide; D010646:Phentolamine