电刺激迷走神经对蟾蜍心率和心率变异的影响

目的:观察不同频率迷走神经刺激对蟾蜍离体心脏的心率及心率变异的影响。方法:将蟾蜍心脏和右侧迷走交感干离体后,以不同频率电刺激神经,记录心电图曲线并作心率变异性(HRV)分析。结果:交感神经阻断后,电刺激迷走交感干,心率(HR)显著下降(P0.01),全部正常心动周期的标准差(SDNN)和相邻正常心动周期差值的均方根(RMSSD)显著升高(P0.01),不同频率刺激组之间没有明显差异;与对照组相比,各指标变化较大;给药组0.2Hz时高频(HF)显著升高(P0.01),低频/高频比值(LF/HF)明显降低(P0.05),0.8Hz时HF和LF/HF接近刺激前水平。结论:一定范围内增加刺激频率,迷走神经降低心率的作用增强;没有交感神经调节条件下的迷走神经对心率和心率变异的调节可能存在不同的机制。

Effect of vagal nerve stimulation on heart rate and heart rate variability in the toads

Objective：To observe the effect of vagal stimulation of different frequencies on heart rate and heart rate variability in the toads.Methods：The animals were prepared to be models of isolated heart with right vagosympathetic trunks,then the nerves stimulated by different frequencies.Collected the electrocardiogram of isolated hearts and analyzed the data with HRV software.Results：Since the effect of sympathetic nerve had been diminished,vagal stimulation resulted in HR being markedly attenuated（P0.01）,SDNN and RMSSD being significantly increased （P0.01）.There was no significant difference in different levels of frequency.Contrast to group control,HR、SDNN and RMSSD each changed clearly.At the frequency of 0.2 Hz,HF increased markedly（P0.01）,and LF/HF decreased obviously（P0.05）in group P＋P.While at the frequency of 0.8 Hz,HF and LF/HF were both around the level of pre-stimulation.Conclusion：These findings suggest that in the certain electrical stimulation frequency range,the effect of vagal on HR increases along with the frequency.Without the effect of sympathetic nerve,the modulation of vagal to HR and HRV may have different ways.