Demichel P, Roquebert J
Br J Pharmacol. 1984 Oct;83(2):505-10. doi: 10.1111/j.1476-5381.1984.tb16514.x.
The actions of raubasine, tetrahydroalstonine and akuammigine were studied on pre- and postsynaptic alpha-adrenoceptors of the rat vas deferens. These three drugs competitively antagonized the effect of noradrenaline on postsynaptic alpha-adrenoceptors, yielding pA2 values of 6.57, 4.56 and 4.68 respectively. The presynaptic alpha-adrenoceptor antagonist activity of the drugs was quantitatively determined by studying the effect of increasing concentrations on the clonidine dose-response curve in the electrically stimulated vas deferens. The inhibitory effect of clonidine could be competitively blocked by these three compounds and the pA2 values for raubasine, tetrahydroalstonine and akuammigine were 6.02, 7.71 and 5.64 respectively. These results indicate that: akuammigine is a very weak antagonist at pre- and postsynaptic sites; raubasine acts preferentially at postsynaptic sites; tetrahydroalstonine is a highly selective presynaptic alpha-adrenoceptor blocking agent. The ratio of the pre/postsynaptic potency declines in the order tetrahydroalstonine greater than akuammigine greater than raubasine.
研究了萝巴新、四氢鸭脚木碱和阿枯米京对大鼠输精管突触前和突触后α-肾上腺素能受体的作用。这三种药物竞争性拮抗去甲肾上腺素对突触后α-肾上腺素能受体的作用，其pA2值分别为6.57、4.56和4.68。通过研究电刺激输精管中不同浓度药物对可乐定剂量反应曲线的影响，定量测定了这些药物的突触前α-肾上腺素能受体拮抗活性。可乐定的抑制作用可被这三种化合物竞争性阻断，萝巴新、四氢鸭脚木碱和阿枯米京的pA2值分别为6.02、7.71和5.64。这些结果表明：阿枯米京在突触前和突触后位点均为非常弱的拮抗剂；萝巴新优先作用于突触后位点；四氢鸭脚木碱是一种高度选择性的突触前α-肾上腺素能受体阻断剂。突触前/后效力之比按四氢鸭脚木碱＞阿枯米京＞萝巴新的顺序下降。
