Reactivation by cysteamine of vascular alpha adrenoceptors blocked by the tetramine disulfide benextramine and interaction of benextramine with phenoxybenzamine.
The tetramine disulfide benextramine irreversibly blocked the noradrenaline-induced contraction of the isolated rabbit aorta in a manner similar to that observed with phenoxybenzamine. Cysteamine abolished the benextramine blockade but not the phenoxybenzamine blockade. Incubation of aortic tissue with benextramine prior to phenoxybenzamine exposure and followed by cysteamine treatment led to a recovery of the noradrenaline response that depended on the dose of benextramine. Thus benextramine protected the alpha adrenoceptors against phenoxybenzamine blockade.
D000818:Animals; D001011:Aorta / Q000187:drug effects; D003538:Cystamine / Q000031:analogs & derivatives* / Q000494:pharmacology; D003543:Cysteamine / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D066298:In Vitro Techniques; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D009200:Myocardial Contraction / Q000187:drug effects; D009638:Norepinephrine / Q000037:antagonists & inhibitors; D010643:Phenoxybenzamine / Q000037:antagonists & inhibitors*; D051381:Rats; D011941:Receptors, Adrenergic / Q000187:drug effects*; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects*
D011941:Receptors, Adrenergic; D011942:Receptors, Adrenergic, alpha; D010643:Phenoxybenzamine; D003543:Cysteamine; C029998:benextramine; D003538:Cystamine; D009638:Norepinephrine