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电刺激迷走交感干对蟾蜍心率及心率变异的影响

发布时间:2018-09-08 06:56
【摘要】: 前言 心率变异(heart rate variability,HRV)是指逐次窦性心动周期之间的时间差异性,自主神经通过调节窦性心率导致心率快慢波动,从而导致心率变异的发生。交感神经系统(sympathetic nervous system,SNS)和副交感神经系统(parasympatheticnervous system,PNS)的调节作用可通过HRV的变化而表达出来。因此HRV能反映自主神经系统(autonomic nervous system,ANS)的活动并可定量评估SNS和PNS张力及其平衡性,从而可以判断心血管疾病的病情及预后,是预测心源性猝死和心律失常性事件的一个有价值的指标。 在体情况下,HRV的测量受神经、呼吸、体位、压力感受器、体温调节等多种因素的影响,这使得HRV分析起来较为复杂,而对离体非生理条件下自主神经活动对心脏HRV的影响的了解还较少。目前研究认为,HRV功率谱不能直接反映自主神经整体活动,而是更为精确地反映自主神经系统在心脏水平的调节,但是目前对HRV的神经调节机制还不十分清楚。本研究旨在去除体液、体温等多种因素的影响,通过电刺激迷走交感干,观察迷走神经对HR和HRV的影响,探讨迷走神经对HRV的调节机制。 材料与方法 一、实验动物处理 选用中华蟾蜍,体重35-50g,由中国医科大学动物中心提供。蟾蜍人工饲养,保持室温24±2℃,湿度(55±5)%。在实验中随机分组。所有ECG数据采集均在上午9:30以后进行。 二、实验动物分组 将蟾蜍随机分成两组,对照组和给药组,具体如下: 1、对照组(Control组,n=10),离体心脏始终用任氏液灌流。 2、给药组(Phe+Pro组,n=10),先用任氏液灌流离体心脏40min,然后用含有Phe(1.5μmol/L)和Pro(1.5μmol/L)的任氏液持续灌流。 三、心电图采集 制作心脏-右侧迷走神经交感干标本后,离体心脏固定于四腔器官浴槽系统内,恒压灌流,神经置于刺激电极上,信号采集系统的记录电极固定于浴槽周围,另一端与计算机连接,记录心电信号至实验结束。 四、电刺激迷走交感干 对照组术后80min、给药组给药后40min进行电刺激10min,每个频率间间歇10min,顺序随机。 五、心率变异分析 选取心脏离体30min后、给药30min后(对照组离体70min后)、电刺激时和电刺激后完整无干扰的HR稳定的连续5min ECG,用HRV分析软件进行分析。 六、统计学处理 用SPSS软件对实验数据进行统计学处理;数据均以(?)±s表示,P<0.05表示差异有统计学意义。 实验结果 1、以不同频率刺激迷走交感干,对照组HR明显降低,但各频率水平之间没有差异。SDNN在0.4Hz时明显升高,0.6Hz和0.8Hz时变化显著,RMSSD在各频率水平均显著升高,SDNN和RMSSD各频率之间没有差异。LF在0.4Hz明显降低,其他频率显著降低,各频率之间没有差异。HF在0.6Hz时明显升高,其它频率均显著升高,各频率之间没有差异。LF/HF在刺激时各频率均明显降低;0.2Hz与0.8Hz之间差异显著。刺激停止后,各指标与刺激前相比没有差异。 2、随着刺激频率水平的增加,给药组HR显著降低,0.2Hz与0.6Hz、0.4Hz与0.8Hz之间、0.2Hz与0.8Hz之间HR差异显著。SDNN和RMSSD在各频率水平均显著升高,各频率之间没有差异。LF和HF在0.2Hz刺激时变化显著,0.4Hz时变化明显,0.6Hz和0.8Hz时变化不明显;0.2Hz与0.8Hz之间差异显著。LF/HF在0.2Hz刺激时明显降低,0.8Hz时与给药后LF/HF接近;0.2Hz与0.8Hz之间差异显著。刺激停止后,各指标与刺激前相比都有升高,但无统计学意义。 讨论 电刺激迷走交感干时,交感迷走失衡,对照组和给药组HR和HRV都发生了变化。对照组HR在各个频率水平均降低,各水平之间没有差异,而在给药组,由于酚妥拉明和普萘洛尔阻断了交感神经加快心率的作用,不仅HR在各个频率水平均降低,而且在0.2Hz与0.6Hz之间、0.4Hz与0.8Hz、0.2Hz与0.8Hz之间HR差异显著;两组相比,给药组下降速度明显快于对照组,表明在本实验使用的频率范围(0.2-0.8Hz)内,电刺激频率越大,迷走神经对心率的作用越强,心率也就越低。 SDNN和RMSSD在对照组和给药组电刺激时均显著升高,但是各个刺激频率水平之间并没有明显差异。推测在缺失完整的心脏自主神经活动调控的条件下,HRV时域指标的简单测量不能准确地定量测量迷走神经紧张性。 对照组中,刺激迷走交感干时,HF明显升高,但是由于交感神经调节的存在,不同频率水平的电刺激之间HF没有明显差异。给药组HF在0.2Hz和0.4Hz时明显升高,0.6Hz和0.8Hz时变化不明显。相对应的,LF/HF也是类似的变化,在0.2Hz和0.4Hz时明显降低,0.6Hz和0.8Hz时变化不明显。这些结果表明,交感神经在心率变异调节中也具有重要的作用。在刺激频率较低时,HF较高,LF/HF较低,由此推测在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。 结论 迷走神经对心率有直接调节作用,在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。
[Abstract]:Preface
Heart rate variability (HRV) refers to the time difference between successive sinus cardiac cycles. Autonomic nerves cause heart rate fluctuations by regulating sinus heart rate, resulting in heart rate variability. Sympathetic nervous system (SNS) and parasympathetic nervous system (PNS) Therefore, HRV can reflect the activity of autonomic nervous system (ANS) and quantitatively evaluate the tension and balance of SNS and PNS, thus judging the condition and prognosis of cardiovascular diseases, and is a valuable predictor of sudden cardiac death and arrhythmia events. Indicators.
In vivo, the measurement of HRV is influenced by many factors, such as nerve, respiration, posture, baroreceptor, temperature regulation and so on. This makes the analysis of HRV more complicated. However, the influence of autonomic nerve activity on heart HRV under non-physiological conditions in vitro is still poorly understood. The purpose of this study was to investigate the effects of vagus nerve on HRV and HRV by stimulating vagal sympathetic trunk to observe the effect of vagus nerve on HR and HRV and to explore the regulation of vagus nerve on HRV. Mechanism.
Materials and methods
Laboratory animal treatment
Bufo gargarizans, weighing 35-50g, were reared in captivity at room temperature of 24 2 C and humidity of 55 (5)%. All ECG data were collected after 9:30 a.m.
Two, experimental animals grouping
The toads were randomly divided into two groups, the control group and the drug delivery group.
1, in the control group (group Control, n=10), the isolated heart was perfused with Ren's fluid.
2. In the Phe+Pro group (n=10), the isolated heart was perfused with Ren's solution for 40 minutes, and then perfused with Ren's solution containing Phe (1.5 micromol/L) and Pro (1.5 micromol/L).
Three, ECG acquisition.
The isolated heart was fixed in the four-chamber organ bath system, perfused under constant pressure, and the nerve was placed on the stimulating electrode. The recording electrode of the signal acquisition system was fixed around the bath, and the other end was connected with the computer to record the ECG signal until the end of the experiment.
Four, electrical stimulation of vagal sympathetic trunk.
The control group was given electric stimulation for 10 minutes at 40 minutes after the operation, with an interval of 10 minutes at each frequency.
Five, heart rate variability analysis
After 30 minutes of isolated heart, 30 minutes after administration (70 minutes in control group), the intact and non-disturbing HR-stable ECG was selected and analyzed by HRV analysis software.
Six, statistical processing
The experimental data were statistically processed by SPSS software, and the data were all expressed as (?) + s, P < 0.05, showing significant difference.
experimental result
1. Stimulating the vagal sympathetic trunk with different frequencies, the HR of the control group decreased significantly, but there was no difference among the frequencies. SDNN increased significantly at 0.4 Hz, RMSSD increased significantly at 0.6 Hz and 0.8 Hz, and there was no difference between the frequencies of SDNN and RMSSD. There was no difference. HF increased significantly at 0.6 Hz, other frequencies increased significantly, and there was no difference between the frequencies. LF / HF decreased significantly at stimulation, and there was a significant difference between 0.2 Hz and 0.8 Hz. After stimulation stopped, there was no difference between the indexes before and after stimulation.
2. With the increase of stimulation frequency, HR of the treatment group decreased significantly, and there was a significant difference between 0.2Hz and 0.6Hz, 0.4Hz and 0.8Hz, 0.2Hz and 0.8Hz. SDNN and RMSSD increased significantly at all frequencies, but there was no difference between them. LF/HF decreased significantly at 0.2 Hz stimulation, approached LF/HF at 0.8 Hz and was significantly different between 0.2 Hz and 0.8 Hz.
discuss
HR and HRV in the control group decreased at all frequencies, but there was no difference between them. In the treatment group, phentolamine and propranolol blocked the effect of sympathetic nerve on heart rate, and HR decreased at all frequencies. The HR difference between 0.4Hz and 0.8Hz, 0.2Hz and 0.8Hz was significant between 0.2Hz and 0.6Hz. Compared with the control group, the decrease rate of HR in the treatment group was faster than that in the control group, indicating that the greater the frequency of electrical stimulation used in this experiment (0.2-0.8Hz), the stronger the effect of vagus nerve on heart rate, the lower the heart rate.
Simple measurements of HRV time domain indices could not accurately quantify vagal nerve tension without complete regulation of cardiac autonomic nervous activity.
In the control group, HF increased significantly when stimulating the vagal sympathetic trunk, but there was no significant difference in HF between different frequency levels due to the existence of sympathetic nerve regulation. These results suggest that sympathetic nerves also play an important role in the regulation of heart rate variability. At low stimulation frequencies, HF is higher and LF/HF is lower. It is speculated that there may be different mechanisms for the regulation of heart rate and heart rate variability by vagus nerves without sympathetic nerve regulation.
conclusion
Vagus nerve can directly regulate heart rate, and there may be different mechanisms for regulating heart rate and heart rate variability without sympathetic regulation.
【学位授予单位】:中国医科大学
【学位级别】:硕士
【学位授予年份】:2009
【分类号】:R331

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