苄基四氢巴马汀对α和β等受体的影响

苄基四氢巴马汀(BTHP)使苯福林对大鼠肛尾肌和兔主动脉条作用的累积量效曲线平行右移,最大反应不压低,pA₂值分别为5.86和5.8,但对甲氧明和B-HT920升高DP作用的量效曲线无明显影响。BTHP可使异丙肾上腺素和组胺正性频率作用的量效曲线非平行右移,最大反应压低。BTHP还能明显缩短大鼠再灌流所致心律失常的持续时间。结果提示,BTHP对α₁受体的阻断及对β和H₂受体的非竞争性拮抗作用可能与该药抗心律失常作用有部分关系但并非其主要机理。

Effects of benzyltetrahydropalmatine on alpha, beta and other receptors

Benzyltetrahydropalmatine (BTHP) produced parallel shift of the cumulative dose-response curves for phenylephrine in rabbit aortic strips and rat anococcygeus muscles to the right. Their PA₂ values were found to be 5.8 and 5.86 respectively. In pithed rats, the dose-response curves of methoxamine and B-HT 920 were not altered by BTHP 5～10 mg/kg which could increase the diastolic pressure. However, the rise in DP was not blocked by yohimbine 1～2 mg/kg. In isolated spontaneously beating guinea pig atria, the positive chronotropic action of both Iso and His can be antagonized by BTHP in a non-competitive manner. The pD₂' value for Iso was shown to be 4. In addition, the arrhythmia induced by reperfusion in rats was also antagonized by BTHP 5mg/kg.These results suggest that the blocking action of BTHP on α₁-and β-adrenoceptors and H₂-receptor are probably partially associated with its antiarrhythmic.