title: Vascular effects of ergot alkaloids: a study on human basilar arteries.
abstract: Postmortem examinations on human basilar arteries were performed in vitro by recording isometric tension from spiral strips in tissue baths at 37 degrees C. Antagonism of 5-HT by ergotamine, dihydroergotamine and methysergide was of the non-competitive type, that of noradrenaline was either absent (i.e. ergotamine) or considerably weaker. In addition each ergot alkaloid acted as a partial agonist in the following order of efficacy: ergotamine greater than dihydroergotamine greater than methysergide, producing pD2 values of 9.30, 9.60 and 7.10 respectively. Evidence is provided that the stimulant activity of ergotamine is mediated through 5-HT receptors. The present results are compared to those obtained on isolated human vein strips as well as to those on canine blood vessels.
mesh_terms: D001488:Basilar Artery / Q000187:drug effects; D003042:Cocaine / Q000494:pharmacology; D004087:Dihydroergotamine / Q000494:pharmacology; D004876:Ergot Alkaloids / Q000494:pharmacology*; D004878:Ergotamine / Q000037:antagonists & inhibitors; D006801:Humans; D066298:In Vitro Techniques; D008784:Methysergide / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D009638:Norepinephrine / Q000494:pharmacology; D012701:Serotonin / Q000494:pharmacology
chemical_list: D004876:Ergot Alkaloids; D012701:Serotonin; D004087:Dihydroergotamine; D003042:Cocaine; D004878:Ergotamine; D009638:Norepinephrine; D008784:Methysergide