迷走神经和交感神经系统不同活动状态对心率变异性的影响

EFFECT OF ACTIVITIES OF VAGI AND SYMPATHETIC NERVOUS SYSTEM ON HEART RATI VARIABILITY

实验在氯醛糖加氨基甲酸乙酯麻醉的新西兰兔上进行。记录血压、心率、心电图并对心电R－R间期（RRI）作功率谱密度（PSD）分析。以单调性电刺激和低频率的波动性电刺激分别刺激减压神经、疑核和右侧迷走神经外周端，观察到低频率的波动性刺激对增加PSD中低频成分（LF）的作用比单调性电刺激更大（P＜0．05）。注射新福林仅在头一个256个心动周期时间内引起总变异性（TV）、LF、PSD中高频成分（HF）。LF／HF比值和PSD中极低频成分（VLF）增大（P＜0．05～0．01）。为观察交感神经在不同活动状态下对心率变异性（HRV）的影响，在下丘脑室旁核周围区微量注射高半胱氨酸（DLH），使交感神经系统兴奋。首次注射DLH可使TV、VLF、LF和LF／HF对增大（P＜0．05），而连续注射几次DLH，HRV无显著变化。结果表明：HRV主要反映迷走神经和交感神经冲动发放的波动，即它代表迷走神经和交感神经紧张性的变异。

Experiments were performed on rabbits anaesthetized with urethane and chloralose.The electrocardiogram(ECG), heart rate (HR), and blood pressure(BP) wererecorded and the power spectrum density (PSD) of R-R interval was analysed by acomputer. The low frequency component (LF) was higher during the respectivestimulation of the nucleus ambiguus, depressor nerve, and the peripheral end of rightvagus with a low frequency fluctuant style than with a monotonous style (P<0.05).Intravenous infusion of phenylephrine resulted in increases of total variance of RRI (TV),very low frequency components (VLF), LF, high frequency components (HF) and LF/HF during the first 256 RRI only (P<0.05~0.01). In order to observe the influence ofdifferent activities of sympathetic nerves on heart rate variability (HRV), DLhomocysteine(DLH) was microinjected into the vicinity of N. Paraventricularis ofhypothalamus. This injection caused imcreases of the TV, LF, LF/HF and VLF duringthe rising Phase Of BP and HR, but no significant change occurred at the plateau period ofhigh BP and HR. These results supest that heart rate variability mainly reflects thefluctuation of vagal and sympathetic tone.