1-(对羟苄基)-N-甲基-6-甲氧基-7-羟基异喹啉对α肾上腺素受体的作用

在大鼠输精管上,BMIQ 10μmol/L和YHB 1μmol/L都能使CLN的量效曲线平行右移,最大反应不变,表明二者均能竞争性地阻断突触前α_2受体,其pA_2值分别为6.69和7.8.大鼠肛尾肌实验表明,BMIQ亦有竞争性拮抗突触后α_1受体作用,pA_2值为5.14。其α_2/α_1阻断作用之比率为35.5,说明BMIQ对α_2受体的选择性大于α_1受体.BMIQ和YHB在毁脊髓大鼠标本上,均能使B—HT920升高舒张血压的量效曲线平行右移,最大反应不变.二者的剂量比率分别为2.7和14.8,且BMIQ抗突触后膜α_2受体作用仅为YHB的1/5.5。

Effects of 1-(p-hydroxybenzyl)-N-methyl-6-methoxy-7-hydroxyisoquinoline on α-adrenoceptors

In isolated rat vas defe-rens,1-(p-hydroxy-benzyl)-N-methyl-6-methoxy-7-hydroxyisoquinoline (BMIQ)10 μmol / L and yohimbine 1μmol / L shifted clonidine cumulative dose-response curves rightward parallelly without change the maximal response.The pA2 values of BMIQ.and yohimbine were 6.69 and 7.8 respectively.In addition,BMIQ could competitively antagonize the contractive action of phenylephrine in rat anococcygeus muscles.The pA2value of BMIQ was 5.14.In pithed rat BMIQ antagonized the effect of B-HT920 in increasing diastolic pressure.It shifted the dose-response curve for B-HT920 parallelly to the right without affecting the maximal effect as yohimbine.YHB was 5.5 fold more than BMIQ in itspotency.The dose-response curves for phenylephrine was not altered by BMIQ.The above results indicate that BMIQ possesses competitive α2 and α1 blocking action and its selective ratio(α2/α1)was 35.5,indicating that BMIQ is a more selective α2-adrenoceptor antagonist.