Lew M J, Angus J A
Eur J Pharmacol. 1984 Feb 10;98(1):27-34. doi: 10.1016/0014-2999(84)90105-5.
Benextramine, a covalently binding alpha-adrenoceptor blocking agent, potentiated the action of noradrenaline but not isoprenaline in guinea pig isolated right atria. This potentiation was probably caused by inhibition of neuronal uptake. When the benextramine was washed from the tissues for 60 min, no potentiation of the action of noradrenaline was observed. This easily reversed inhibition of neuronal uptake by benextramine contrasts with the effects of desipramine and phenoxybenzamine because the potentiating effect of these drugs was unaffected by 60 min of washing. The presence of benextramine also caused a small tachycardia in both rabbit and guinea pig right atria which was probably due to the release of endogenous noradrenaline. Clonidine a presynaptic alpha 2-adrenoceptor agonist, inhibited the responses to electrical field stimulation. Pretreatment with benextramine greatly diminished the effect of clonidine. This alpha 2-adrenoceptor antagonism was not reversed by washing the benextramine from the tissue for 240 min. We conclude that benextramine is a readily reversible inhibitor of neuronal uptake and an irreversible antagonist of presynaptic alpha 2-adrenoceptors.
苄非他明是一种具有共价结合作用的α-肾上腺素能受体阻断剂，它能增强去甲肾上腺素对豚鼠离体右心房的作用，但对异丙肾上腺素无此作用。这种增强作用可能是由抑制神经元摄取所致。当将苄非他明从组织中冲洗60分钟后，未观察到去甲肾上腺素作用的增强。苄非他明对神经元摄取的这种易于逆转的抑制作用，与地昔帕明和酚苄明的作用形成对比，因为这些药物的增强作用不受60分钟冲洗的影响。苄非他明的存在还会使兔和豚鼠右心房出现轻微的心动过速，这可能是由于内源性去甲肾上腺素的释放所致。可乐定是一种突触前α2-肾上腺素能受体激动剂，它能抑制对电场刺激的反应。用苄非他明预处理可大大减弱可乐定的作用。将苄非他明从组织中冲洗240分钟也不能逆转这种α2-肾上腺素能受体拮抗作用。我们得出结论，苄非他明是一种易于逆转的神经元摄取抑制剂和突触前α2-肾上腺素能受体的不可逆拮抗剂。
