In vitro selectivity of lisuride and other ergot derivatives for alpha 1- and alpha 2-adrenoceptors.
The alpha-adrenoceptor agonist and antagonist actions of lisuride and other ergot derivatives were assessed in spleen strips (alpha 1-adrenoceptor) and transmurally stimulated ileal preparations (alpha 2-adrenoceptor) from the guinea-pig. The compounds tested were devoid of alpha-adrenoceptor agonistic activity, however many were selective alpha-adrenoceptor antagonists. Lisuride was alpha 2-selective, having a pA2 value of 9.70 in guinea-pig ileal and 7.47 in splenic preparations. Conversely, bromocriptine was alpha 1-selective with a pA2 of 7.46 in spleen strips; it had no measurable effect in the ileum.
D000818:Animals; D001971:Bromocriptine / Q000494:pharmacology; D003000:Clonidine / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004873:Ergolines / Q000494:pharmacology*; D004876:Ergot Alkaloids / Q000494:pharmacology*; D006168:Guinea Pigs; D007082:Ileum / Q000502:physiology; D066298:In Vitro Techniques; D008090:Lisuride / Q000494:pharmacology*; D009119:Muscle Contraction / Q000187:drug effects*; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects; D013154:Spleen / Q000502:physiology
D004873:Ergolines; D004876:Ergot Alkaloids; D011942:Receptors, Adrenergic, alpha; D001971:Bromocriptine; D008090:Lisuride; D003000:Clonidine