【摘要】： 前言 心率變異(heart rate variability,HRV)是指逐次竇性心動周期之間的時間差異性,自主神經(jīng)通過調(diào)節(jié)竇性心率導(dǎo)致心率快慢波動,從而導(dǎo)致心率變異的發(fā)生。交感神經(jīng)系統(tǒng)(sympathetic nervous system,SNS)和副交感神經(jīng)系統(tǒng)(parasympatheticnervous system,PNS)的調(diào)節(jié)作用可通過HRV的變化而表達出來。因此HRV能反映自主神經(jīng)系統(tǒng)(autonomic nervous system,ANS)的活動并可定量評估SNS和PNS張力及其平衡性,從而可以判斷心血管疾病的病情及預(yù)后,是預(yù)測心源性猝死和心律失常性事件的一個有價值的指標。 在體情況下,HRV的測量受神經(jīng)、呼吸、體位、壓力感受器、體溫調(diào)節(jié)等多種因素的影響,這使得HRV分析起來較為復(fù)雜,而對離體非生理條件下自主神經(jīng)活動對心臟HRV的影響的了解還較少。目前研究認為,HRV功率譜不能直接反映自主神經(jīng)整體活動,而是更為精確地反映自主神經(jīng)系統(tǒng)在心臟水平的調(diào)節(jié),但是目前對HRV的神經(jīng)調(diào)節(jié)機制還不十分清楚。本研究旨在去除體液、體溫等多種因素的影響,通過電刺激迷走交感干,觀察迷走神經(jīng)對HR和HRV的影響,探討迷走神經(jīng)對HRV的調(diào)節(jié)機制。 材料與方法 一、實驗動物處理 選用中華蟾蜍,體重35-50g,由中國醫(yī)科大學(xué)動物中心提供。蟾蜍人工飼養(yǎng),保持室溫24±2℃,濕度(55±5)%。在實驗中隨機分組。所有ECG數(shù)據(jù)采集均在上午9:30以后進行。 二、實驗動物分組 將蟾蜍隨機分成兩組,對照組和給藥組,具體如下: 1、對照組(Control組,n=10),離體心臟始終用任氏液灌流。 2、給藥組(Phe+Pro組,n=10),先用任氏液灌流離體心臟40min,然后用含有Phe(1.5μmol/L)和Pro(1.5μmol/L)的任氏液持續(xù)灌流。 三、心電圖采集 制作心臟-右側(cè)迷走神經(jīng)交感干標本后,離體心臟固定于四腔器官浴槽系統(tǒng)內(nèi),恒壓灌流,神經(jīng)置于刺激電極上,信號采集系統(tǒng)的記錄電極固定于浴槽周圍,另一端與計算機連接,記錄心電信號至實驗結(jié)束。 四、電刺激迷走交感干 對照組術(shù)后80min、給藥組給藥后40min進行電刺激10min,每個頻率間間歇10min,順序隨機。 五、心率變異分析 選取心臟離體30min后、給藥30min后(對照組離體70min后)、電刺激時和電刺激后完整無干擾的HR穩(wěn)定的連續(xù)5min ECG,用HRV分析軟件進行分析。 六、統(tǒng)計學(xué)處理 用SPSS軟件對實驗數(shù)據(jù)進行統(tǒng)計學(xué)處理;數(shù)據(jù)均以(?)±s表示,P＜0.05表示差異有統(tǒng)計學(xué)意義。 實驗結(jié)果 1、以不同頻率刺激迷走交感干,對照組HR明顯降低,但各頻率水平之間沒有差異。SDNN在0.4Hz時明顯升高,0.6Hz和0.8Hz時變化顯著,RMSSD在各頻率水平均顯著升高,SDNN和RMSSD各頻率之間沒有差異。LF在0.4Hz明顯降低,其他頻率顯著降低,各頻率之間沒有差異。HF在0.6Hz時明顯升高,其它頻率均顯著升高,各頻率之間沒有差異。LF/HF在刺激時各頻率均明顯降低;0.2Hz與0.8Hz之間差異顯著。刺激停止后,各指標與刺激前相比沒有差異。 2、隨著刺激頻率水平的增加,給藥組HR顯著降低,0.2Hz與0.6Hz、0.4Hz與0.8Hz之間、0.2Hz與0.8Hz之間HR差異顯著。SDNN和RMSSD在各頻率水平均顯著升高,各頻率之間沒有差異。LF和HF在0.2Hz刺激時變化顯著,0.4Hz時變化明顯,0.6Hz和0.8Hz時變化不明顯;0.2Hz與0.8Hz之間差異顯著。LF/HF在0.2Hz刺激時明顯降低,0.8Hz時與給藥后LF/HF接近;0.2Hz與0.8Hz之間差異顯著。刺激停止后,各指標與刺激前相比都有升高,但無統(tǒng)計學(xué)意義。 討論 電刺激迷走交感干時,交感迷走失衡,對照組和給藥組HR和HRV都發(fā)生了變化。對照組HR在各個頻率水平均降低,各水平之間沒有差異,而在給藥組,由于酚妥拉明和普萘洛爾阻斷了交感神經(jīng)加快心率的作用,不僅HR在各個頻率水平均降低,而且在0.2Hz與0.6Hz之間、0.4Hz與0.8Hz、0.2Hz與0.8Hz之間HR差異顯著;兩組相比,給藥組下降速度明顯快于對照組,表明在本實驗使用的頻率范圍(0.2-0.8Hz)內(nèi),電刺激頻率越大,迷走神經(jīng)對心率的作用越強,心率也就越低。 SDNN和RMSSD在對照組和給藥組電刺激時均顯著升高,但是各個刺激頻率水平之間并沒有明顯差異。推測在缺失完整的心臟自主神經(jīng)活動調(diào)控的條件下,HRV時域指標的簡單測量不能準確地定量測量迷走神經(jīng)緊張性。 對照組中,刺激迷走交感干時,HF明顯升高,但是由于交感神經(jīng)調(diào)節(jié)的存在,不同頻率水平的電刺激之間HF沒有明顯差異。給藥組HF在0.2Hz和0.4Hz時明顯升高,0.6Hz和0.8Hz時變化不明顯。相對應(yīng)的,LF/HF也是類似的變化,在0.2Hz和0.4Hz時明顯降低,0.6Hz和0.8Hz時變化不明顯。這些結(jié)果表明,交感神經(jīng)在心率變異調(diào)節(jié)中也具有重要的作用。在刺激頻率較低時,HF較高,LF/HF較低,由此推測在沒有交感神經(jīng)調(diào)節(jié)條件下的迷走神經(jīng)對心率和心率變異的調(diào)節(jié)可能存在不同的機制。 結(jié)論 迷走神經(jīng)對心率有直接調(diào)節(jié)作用,在沒有交感神經(jīng)調(diào)節(jié)條件下的迷走神經(jīng)對心率和心率變異的調(diào)節(jié)可能存在不同的機制。
[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.
【學(xué)位授予單位】：中國醫(yī)科大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2009
【分類號】：R331

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