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我们曾用小鼠血浆cAMP为指标,间接证明去甲乌药碱盐酸盐(dl-demethylcoclaurine HCl简称DMC)是β受体部分激动剂。本文用火鸡红细胞膜制备,测定了DMC和异丙肾上腺素(ISO)对腺苷环化酶(AC)活性的影响,並用放射配基结合测定法,研究了DMC与ISO对β受体的作用。 1.对AC的作用:火鸡红细胞膜内含有丰富的AC及β受体。本文以火鸡红细胞膜为材料,ATP作底物,将膜、ATP、DMC或ISO置于含Mg~(2+)、GG、DTT和茶碱的Tris溶液中(pH7.5),在30℃水浴内温孵15分钟,测定所生成的cAMP作为AC活性的指标。结果表明,DMC和ISO使AC活性增强,其效力随药物浓度的加大而增加。从剂量反应曲线求出DMC和ISO引起AC最大兴奋的半效浓度分别为17.3及8.2μM。当加入GTP 30μM后,DMC及ISO激活AC的作用进一步加强。β阻断剂心得安可阻断DMC和ISO对AC的激活,而α阻断剂酚妥拉明则无此作用。不同浓度的ISO和DMC(1×10~(-5)M)合用时,DMC能加强低浓度ISO激活AC的效力,减弱高浓度ISO的作用。
We have used mouse plasma cAMP as an indicator to indirectly demonstrate that demethylcocrine hydrochloride (DMC) is a beta receptor partial agonist. In this paper, the preparation of turkey erythrocyte membranes was used to determine the effect of DMC and ISO on adenosine cyclase (AC) activity. The radioligand binding assay was used to determine the effect of DMC and ISO on the β receptor effect. 1. The role of AC: turkey erythrocyte membrane is rich in AC and β receptors. In this paper, turkey erythrocyte membrane as material, ATP as a substrate, the membrane, ATP, DMC or ISO containing Mg ~ (2 +), GG, DTT and theophylline Tris solution (pH7.5), at 30 C in a water bath for 15 minutes and the resulting cAMP was measured as an indicator of AC activity. The results showed that DMC and ISO enhanced the activity of AC and its efficacy increased with the increase of drug concentration. From the dose response curve obtained DMC and ISO caused the maximum excitement AC half-effect concentrations were 17.3 and 8.2μM. The effect of DMC and ISO activated AC was further enhanced by adding 30 μM GTP. Beta blockers experience Encore block DMC and ISO on the activation of AC, and α blockers did not have this effect phentolamine. When combined with different concentrations of ISO and DMC (1 × 10 -5 M), DMC can enhance the effect of low concentration of ISO activated AC and weaken the effect of high concentration of ISO.