Evidence in favour of a selective alpha 1-adrenoceptor blocking action of WB 4101 in vivo.
The alpha-adrenoceptor blocking potency of WB 4101 at alpha 1- and alpha 2-adrenoceptors has been investigated in pithed rats. WB 4101 was approximately 97 times more potent at antagonizing the vasopressor responses produced by the selective alpha 1-adrenoceptor agonist phenylephrine, than those produced by the selective alpha 2-adrenoceptor agonist M-7. A dose of WB 4101 (3 mg/kg) that caused extensive blockade of vascular alpha 1-adrenoceptors, but little or no blockade of vascular alpha 2-adrenoceptors, exerted no significant blockade of the presynaptic alpha 2-adrenoceptors in the rat heart. The results support the view that WB 4101 is a highly selective antagonist at alpha 1-adrenoceptors in vivo.
D000317:Adrenergic alpha-Antagonists; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D003000:Clonidine / Q000494:pharmacology; D004146:Dioxanes / Q000494:pharmacology*; D004147:Dioxins / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006339:Heart Rate / Q000187:drug effects; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects
D000317:Adrenergic alpha-Antagonists; D004146:Dioxanes; D004147:Dioxins; D011942:Receptors, Adrenergic, alpha; C010654:(2-(2',6'-dimethoxy)phenoxyethylamino)methylbenzo-1,4-dioxane; D003000:Clonidine