Effects of 7-O-demethylisothalicberine, a bisbenzylisoquinoline alkaloid of Berberis chilensis, on electrical activity of frog cardiac pacemaker cells.
作者信息
Morales M A, Gallardo L R, Martínez J L, Puebla R S, Hernández D A
机构信息
Department of Pharmacology, Faculty of Medicine, University of Chile, Santiago.
出版信息
Gen Pharmacol. 1989;20(5):621-5. doi: 10.1016/0306-3623(89)90097-9.
In spontaneously beating preparations of sinus venosus of the chilean frog Caudiverbera caudiverbera, the electrophysiological effects of 7-O-demethylisothalicberine (7-O-DI) on transitional pacemaker cells were investigated. 2. 7-O-DI in concentration 1 x 10(-4) M blocked the action potential of transitional cells. This blockade was preceded by subthreshold oscillations and depolarization of membrane potential. 3. Lower concentration of the drug to induce complete blockade (5 x 10(-5) M), allowed to observe a great depression of bioelectric cell characteristics in transitional fibres. 4. 7-O-DI induced blockade of transitional cells action potential was preceded by the appearance of a notch in their upstroke and the persistence of a fast depolarizing activity that remained unblocked. This 7-O-DI resistant fast component of the upstroke was blocked by tetrodotoxin. 5. Transitional cells completely blocked by 7-O-DI were depolarized to about 40 mV. 6. The results indicate a close similarity between 7-O-DI and verapamil effects on action potential configuration.
摘要
在智利蛙尾蟾尾静脉窦的自发搏动标本中，研究了7 - O - 去甲基异塔里贝林（7 - O - DI）对过渡性起搏细胞的电生理效应。2. 浓度为1×10⁻⁴ M的7 - O - DI阻断了过渡性细胞的动作电位。这种阻断之前有阈下振荡和膜电位去极化。3. 诱导完全阻断的较低药物浓度（5×10⁻⁵ M），可观察到过渡性纤维中生物电细胞特征的显著抑制。4. 7 - O - DI诱导过渡性细胞动作电位阻断之前，其上升支出现一个切迹，且存在未被阻断的快速去极化活动。这种7 - O - DI抗性的上升支快速成分可被河豚毒素阻断。5. 被7 - O - DI完全阻断的过渡性细胞去极化至约40 mV。6. 结果表明7 - O - DI与维拉帕米对动作电位形态的作用非常相似。
