Evidence for stimulation of 5-HT receptors in canine saphenous arteries by ergotamine.
Changes in tension of spiral strips from dog saphenous arteries were monitored isometrically. Dose-response curves for noradrenaline, 5-HT and ergotamine were established without and after a 30 min incubation with phentolamine or pizotifen. Phentolamine was about 15 times more potent in antagonizing responses to noradrenaline (pA2 value=7.4) than those to 5-HT (pA2 value=6.2) but it was nearly equipotent in antagonizing responses to ergotamine (pA2 value=6.5) and those to 5-HT. Pizotifen was about 500 times less potent in antagonizing noradrenaline effects than 5-HT but again nearly equipotent when tested against ergotamine and 5-HT. It is suggested that in canine saphenous arteries the stimulant activity of ergotamine is mediated mainly through 5-HT receptors.
D000818:Animals; D001158:Arteries / Q000187:drug effects; D004285:Dogs; D004878:Ergotamine / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D005260:Female; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology; D010646:Phentolamine / Q000494:pharmacology; D010918:Pizotyline / Q000494:pharmacology; D011985:Receptors, Serotonin / Q000187:drug effects*; D012701:Serotonin / Q000494:pharmacology; D014666:Vasomotor System / Q000187:drug effects*
D011985:Receptors, Serotonin; D010918:Pizotyline; D012701:Serotonin; D004878:Ergotamine; D009638:Norepinephrine; D010646:Phentolamine