八厘麻毒素对兔心脏电生理参数的影响

Effects of rhomotoxin on electrophysiologic parameters in rabbit heart

目的研究八厘麻毒素(Rh)对在体和离体兔心脏电生理参数的影响。方法使用在体兔心脏模型和Langendorff离体兔心脏灌流模型 ,观察并记录分别用Rh12.5μg·kg-1和25μg·kg-1(iv)或用含Rh浓度为0.34μmol·L-1 和0.68μmol·L-1 的K_H灌注液灌注兔心脏时 ,对在体或离体兔心脏电生理参数的影响。结果在Rh12.5μg·kg-1(iv)后20、40、60和80min,心室舒张阈值 (VDT),有效不应期 (ERP)和相对不应期 (RRP)均无显著变化;而Rh25μg·kg-1(iv)在用药后的同样时间内可见ERP和RRP显著延长(P<0.05)。另用含Rh浓度为0.34μmol·L -1的K_H灌注液行Langendorff灌注 ,心房相对不应期(ARRP)和心房有效不应期(AERP)显著延长 (P<0.05～0.01) ;转用含Rh浓度为0.68μmol·L-1 的K_H灌注液行Lan gendorff灌注 ,心房舒张阈值(ADT)、VDT均明显升高 (P<0.05～0.01) ,且ARRP ,AERP ,心室相对不应期(VRRP)和心室有效不应期(VERP)均显著延长 (P<0.05～0.01)。结论Rh能直接作用于心肌 ,升高心房、心室舒张期阈值和延长心房。

Aim To study effects of rhomotoxin (Rh) on electrophysiologic parameters in rabbit heart. Methods The rabbit hearts in vivo were injected with Rh 12.5 μg·kg-1 , 25 μg·kg-1 or saline iv respectively and the isolated rabbit hearts were perfused by Krebs-Henseleit(K-H) perfusion liquid containing Rh 0.34 μmol·L-1 or 0.68 μmol·L-1. The electrophysiologic parameters were observed before and after drug adminitration.Results At 20,40,60 and 80 min after injection of Rh 12.5 μg·kg-1 iv,the VDT,ERP and RRP had no significant changes; but at 20,40,60 and 80 min after injection of Rh 25 μg·kg-1 iv a significant prolongation of ERP and (or) RRP was found (P<0.05). Perfusing isolated heart with Rh 0.34 μmol·L-1 prolonged ARRP and AERP (P<0.05,P<0.01); while perfusing isolated heart with Rh 0.68 μmol·L-1 increased ADT and VDT (P<0.05,P<0.01) and prolonged ARRP, AERP,VRRP and VERP (P<0.05,P<0.01). Conclusion Rh might have an effect of increasing atrial and ventricular diastolic threshold, which prolongates atrial and ventricular refractory period by direct action on rabbits myocardial muscle.