蝙蝠葛碱抗离体家兔心房压增加所致机电反馈效应的研究

The effects of dauricine on electrophysiologic changes caused by increasing atrial pressure in isolated rabbit hearts

目的探讨心房压增加引起的心肌电生理变化及蝙蝠葛碱对其的影响和机制。方法采用离体Lange-ndoeff心脏模型,观察房压增加前后心肌有效不应期(ERP)、单相动作电位时程(MAPD90)和房颤阈(VFT)的变化,测定各组心房肌Na+、K+和Ca2+水平,并比较蝙蝠葛碱和维拉帕米对上述参数变化的影响。结果房压上升(20cmH2O)引起ERP和MAPD90缩短,AFT下降,蝙蝠葛碱可有效抑制上述变化,且与对照组相比,心房肌Na+、K+和Ca2+水平均有下降(P<0.01);而维拉帕米对此没有明显影响。结论蝙蝠葛碱作为牵张激活性通道阻滞剂,通过抑制非选择性阳离子通道电流而消除超负荷时机电反馈效应。

Objective To study the effects of dauricine on electrophysiological changes of the heart caused by increasing atrial pressure. Method Twenty-four models of isolated Langendoeff-perfused rabbit heart were established and were divided into 3 groups: dauricine group with dauricine added into the infusion fluid, verapamil group, with verapamil added into the infusion fluid, and control group. The caval and pulmonary veins were occluded and the intra-atrial septum was perforated to equalize the pressures of right and left atria. The atrial pressure was altered by changing the height of water column in the catheter inserted into the pulmonary artery. The changes of heart electrophysiological parameters, including effective refractory period (ERP), monophasic action potential duration (MAPD), and atrial fibrillation threshold (AFT), were measured before and after altering the atrial pressure. Results The rising of atrial pressure (+20 cm H2O) led to shortening of ERP and MAPD90, and descent of AFT (all P<0.01). After post-atrial pressure rising ,the content of Na+、K+ and Ca2 in the atrial fluid of the dauricine group didn’t increase, compared with the control group. In contrast, verapamil showed no effects on the pressure-related changes of ERP, MAPD90 and AFT. Conclusion Dauricine inhibits the mechano-electric feedback through inhibition of stretch-activated non-selected positive ion channels.