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目的:研究粉防己碱(Tet)对家犬在体心室肌单相动作电位(MAP)和有效不应期(ERP)的影响,探讨其抗心律失常的可能机制。方法:家犬14只,随机分为Tet组和维拉帕米(Ver)组,记录右室心内膜MAP及心电图Ⅱ导联,比较不同剂量的Tet和Ver对MAP振幅(MAPA)、复极化达50％和90％一点到MAP上升支的水平距离(MAPD50、MAPD90)、ERP及ERP/MAPD90。结果:Tet引起窦性心率减慢,随剂量增加(3～12 mg/kg)ERP延长、ERP/MAPD90增大,但对MAPA、MAPD50、MAPD90无明显影响;而Ver除延长ERP,增大ERP/MAPD90,还缩短MAPD50、MAPD90。结论:Tet对MAP的影响可能除钙拮抗作用外,还有别的离子基础;延长ERP、增大ERP/MAPD90可能是其抗心律失常的机制。
OBJECTIVE: To study the effects of tetrandrine (Tet) on single-phase action potential (MAP) and effective refractory period (ERP) in dogs and to explore the possible mechanisms of antiarrhythmic effects. Methods: Fourteen domestic dogs were randomly divided into Tet group and verapamil (Ver) group. Right ventricle endocardial MAP and electrocardiogram II leads were recorded. Comparison of different doses of Tet and Ver for MAP amplitude (MAPA) and recovery. Polarization reached 50% and 90% at one point to the horizontal distance of the MAP rising branch (MAPD50, MAPD90), ERP, and ERP/MAPD90. Results: Tet caused slowing of sinus rhythm, ERP prolonged and ERP/MAPD90 increased with dose (3 ~ 12 mg/kg), but had no significant effect on MAPA, MAPD50, MAPD90; Ver increased ERP with prolonged ERP. /MAPD90 also shortens MAPD50 and MAPD90. Conclusion: The effects of Tet on MAP may have other ion basis besides calcium antagonistic effect. Prolonging ERP and increasing ERP/MAPD90 may be the mechanism of antiarrhythmic effect.