麻黄果多糖对家兔心室乳头肌电活动的影响

Effect of Ephedra vulgans Fruit Polysaccharide(EVFP) on Electric Potential of Ventricular Papillary Muscle in Rabbits

目的观察麻黄果多糖对家兔离体心室乳头肌动作电位的影响,并探讨其作用机制。方法采用玻璃微电极细胞内纪录方法,描记麻黄果多糖对心室乳头肌静息电位(RP),动作电位幅值(APA),0相最大除极速度(Vmax)、复极至50%和90%(APD50,APD90)的时间的影响,并利用M受体阻断剂和β受体阻断剂,探讨其作用靶点。结果麻黄过多糖灌流5 min时,APD,APD50,APD90均明显延长,后逐渐缩短;10 min时,该3项指标与对照组相比显著缩短。应用M受体阻断剂后,该效应消失;应用β受体阻断剂时,先延长后缩短的效应仍存在。结论麻黄果多糖作用于心室乳头肌M受体,对K+通道有先抑制后易化的双向效应。

Objective To observe the effects and the mechanism of EVFP on electric potential of ventricular papillary muscle in rabbits. Methods The electric potentials of isolated ventrieular papillary muscle were intracellularly recorded. Electrophysiological parameters were： resting potential （RP）, amplitude of action potential （APA）, maximal rate of depolarization of phase 0 （ Vmax）, duration of action potential （ APD）, duration of 50% and 90% depolarization （ APD50 and APD90 ）. The effects and mechanisms of action EVFP on the electric potentials were observed. Results When 120 μmol EVFP had been reperfused for 5 min, the APD, APDs0, and APD90 were prolonged, and then they were shorten gradually. Compared with the controt group, the three indexes were obviously shortened when EVFP reperfused for 10 min. These effects disappeared when block agent of M - receptor was used before EVFP reperfusion. But these effects existed when block agent of β - receptor was used before EVFP reperfusion. Conclusion APD, APDsoand APD90 of ventricular papillary muscle were prolonged by EVFP. The effect may be related to M - receptor.