【作者】 周俐敏；

【导师】 高兴亚； 朱国庆；

【作者基本信息】 南京医科大学 ， 生理学， 2008， 硕士

【摘要】 高血压发病率高,药物治疗效果欠佳。我们既往的研究设计了一种芯片植入式闭环血压调控系统,已有实验结果表明该芯片系统对正常家兔、正常大鼠以及自发性高血压大鼠（SHR）均有很好的降压效果。为进一步检验芯片系统对继发性高血压的降压效果,本研究在前期研究结果的基础上将芯片系统用于两肾一夹（2K1C）肾血管性高血压大鼠上进行相关的动物实验,评价芯片系统对继发性高血压大鼠的降压效应,并对芯片系统的降压机制进行初步探讨,主要观察芯片系统对肾交感神经活动（RSNA）和压力感受性反射敏感性（BRS）的影响。另外还对芯片系统可能存在的风险或副作用进行了研究,主要包括对血浆肾素水平和血流动力学的影响。大鼠随机分为两组,一组将右肾动脉部分狭窄、左肾保持完整制成2K1C肾血管性高血压大鼠模型（2K1C组）;一组行假手术作为对照组（Sham组）。大鼠均采用腹腔注射氨基甲酸乙酯(1.2g.kg^-1)麻醉,颈静脉插管用于静脉给药,股动脉插管用于血压信号的采集。分离左侧主动脉降压神经（ADN）,将微型银制刺激电极放置于ADN上,接受来自芯片系统的电刺激进行降压。芯片系统工作时通过闭环负反馈模式实时、动态控制血压。记录RSNA作为评价交感神经活动的指标;静脉注射不同剂量的苯肾上腺素升高血压,将平均动脉压变化与相应的反射性心率变化进行直线回归分析,以直线斜率反映BRS;利用酶联免疫吸附技术（ELISA）测定大鼠血浆去甲肾上腺素水平和血浆肾素水平;经右颈总动脉逆行插管至左心室腔测定左心室舒张末期压（LVEDP）,左心室发展压（LVDP）和左心室内压变化最大速率（LVdP/dtmax）等作为观察芯片系统对心功能影响的指标;。主要的研究结果如下:1、降压效应:2K1C大鼠的血压显著高于Sham组大鼠（138.2±2.5mmHg vs.9702±4.3 mmHg,P＜0.05）;芯片系统使2K1C大鼠升高的血压恢复正常（138.2±2.5 mmHg vs.98.6±7.8 mmHg,P＜0.05）,降压幅度显著大于Sham组大鼠（-47.1±2.4 mmHg vs.-6.9±4.0 mmHg,P＜0.05）;芯片系统调控时2K1C大鼠的心率下降幅度低于Sham组大鼠（-28.8±12.7 bpm vs.-51.2±9.4bpm,P＜0.05）2、对RSNA的影响:2K1C大鼠的基础RSNA显著高于Sham组大鼠（75.4±4.7%vs.46.7±4.3%,P＜0.05）;芯片系统使2K1C大鼠和Sham组大鼠的RSNA都显著减小,但两组之间下降幅度无显著差异（-38.1±2.7%vs.-36.9±3.2%,P＞0.05）。3、对血浆去甲肾上腺水平的影响:2K1C大鼠血浆去甲肾上腺素水平显著高于sham组大鼠（1827.3±45.9pg/ml vs.760.7±28.6 pg/ml,P＜0.05）;芯片系统使2K1C大鼠增高的血浆去甲肾上腺素水平恢复正常（1827.3±45.9 pg/ml vs.922.3±124.5 pg/ml,P＜0.05）;4、对BRS的影响:2K1C大鼠的BRS基础水平比Sham组大鼠BRS基础水平显著降低(-1.53±0.24 beats·min^-1·mmHg^-1vs.-0.15±0.54 beats·min^-1·mmHg^-1,P＜0.05);芯片系统调控过程中2K1C大鼠的BRS显著提高,但仍低于Sham组大鼠的BRS(-1.94±0.30beats·min^-1·mmHg^-1vs.-3.47±0.49 beats·min^-1·mmHg^-1,P＜0.05)。5、血浆肾素水平的影响:芯片系统调控后2K1C大鼠血浆肾素水平无显著增加（4.03±0.6ng/ml vs.4.88±0.8 ng/ml,P＞0.05）6、对心功能的影响:芯片系统调控前2K1C大鼠LVDP和LVdP/dtmax值均显著高于Sham组大鼠（LVDP:172.7±9.8mmHg vs.131.5±9.9 mmHg,P＜0.05;LVdP/dtmax:5314.4±318.9mmHg/sec Vs.3979.1±219.6mm Hg/sec,P＜0.05）;芯片系统使2K1C大鼠增高的LVDP和LVdP/dtmax降至正常水平（LVDP:121.1±7.9 mmHg;LVdP/dtmax:4023.1±212.8 mmHg/sec）。本研究结果表明,芯片系统可显著降低2K1C组和sham组大鼠动脉血压,可使2K1C组大鼠的动脉血压恢复到接近正常水平;2K1C大鼠基础RSNA显著增强,芯片系统显著降低2K1C组大鼠增强的RSNA;芯片系统降低2K1C大鼠血压的程度显著大于Sham组大鼠,但对两组大鼠的RSNA的抑制作用无显著差异;芯片系统改善2K1C大鼠显著降低的BRS;芯片系统使2K1C大鼠显著增高的血浆去甲肾上腺素水平恢复正常,而对血浆肾素水平无显著影响;芯片系统使2K1C大鼠增强的心功能恢复正常,在芯片系统调控过程中,LVDP、LVEDP和LVdP/dtmax虽有所降低,但均在正常范围内。综上所述,芯片系统可有效调控肾血管性高血压大鼠的动脉血压,使肾血管性高血压大鼠增强的交感神经活动、升高的血浆去甲肾上腺素水平和心功能恢复正常,并改善肾血管性高血压大鼠显著降低的BRS。更多还原

【Abstract】 Hypertension is one of the most popular cardiovascular diseases. Medication is a therapy of non-physiologic regulation on blood pressure, and usually produces many side effects. Our previous studies showed a chip system can successfully control blood pressure in normal rabbits, rats and spontaneously hypertensive rats （SHR）. In the present study, in order to investigate the anti-hypertensive effects of the chip system in secondary hypertension, we tested the depressor effects of the chip system in anaesthetic two-kidney, one-clip （2K1C） renovascular hypertensive rats and compared with sham-operated rats. The effects of the chip system on the mean arterial pressure （MAP）, heart rate （HR）, renal sympathetic nerve activity （RSNA）, the plasma norepinephrine concentration and plasma renin concentration, the baroreflex Sensitivity （BRS） and cardiac contractile state were determined in these rats. The rats were randomly subjected to two-kidney, one-clip （2K1C） to induce renovascular hypertension or sham operation.Each rat was anesthetized with intraperitoneal injection of urethane （1.2 g/kg）. The left aortic depressor nerve （ADN） was isolated and identified. A pair of thin silver electrodes was hooked around the nerve preparing for the electrical stimulations. The chip system receives the information of arterial pressure from transducer in the right femoral artery. The waves of arterial pressure are sampled, operated and processed in the chip system. Then, electrical signals with different frequencies are produced by the chip system to stimulate the left ADN. The plasma norepinephrine concentration and plasma renin concentration were measured by enzyme-linked immunosorbent assay （ELISA）. To determine the left ventricle （LV） pressures, the transducer was sent into LV. The left ventricle end-diastolic pressure （LVEDP）, left ventricle developing pressure （LVDP） and maximal rise rate of the left ventricle pressure （LVdP/dtmax） were determined to provide a functional index of cardiac contractile state. The baroreceptor reflex was induced by repeated bolus intravenous injections of graded doses of phenylephrine. The BRS was evaluated in each rat by regression line for the relationship between the changes in HR and the changes in MAP for each data point obtained with graded injection of phenylephrine. The slope of the line expressing the relationship (beats·min^-1·mmHg^-1) was used as an index of the BRS. The primary findings were as following:1. The MAP was much higher in 2K1C rats than in sham-operated rats （138.2±2.5 vs. 97.2±4.3 mmHg, P<0.05）. Stimulation of the ADN with the chip system normalized the MAP in 2K1C rats（138.2±2.5 mmHg vs. 98.6±7.8 mmHg, P<0.05）. The chip system regulation caused a greater fall in MAP （-47.1±2.4 mmHg vs. -6.9±4.0 mmHg, P<0.05）, but a smaller fall in HR （-28.8±12.7 bpm vs. -51.2±9.4 bpm, P<0.05） in 2K1C rats than in sham-operated rats.2. The baseline RSNA was much higher in 2K1C rats than in sham-operated rats （75.4±4.7% vs. 46.7±4.3%, P<0.05）. Stimulation with the chip system decreased the RSNA in both 2K1C rats and sham-operated rats. There was no significant difference in the percent change of the RSNA caused by the stimulation between 2K1C rats and sham-operated rats （-38.1±2.7% vs. -36.9±3.2 %, P>0.05）.3. The plasma norepinephrine concentration was much higher in 2K1C rats than in sham-operated rats （1827.3±45.9pg/ml vs. 760.7±28.6pg/ml, P<0.05 ）. The chip system regulation normalized the plasma norepinephrine concentration in 2K1C rats （1827.3±45.9 pg/ml vs. 922.3±124.5 pg/ml, P<0.05）.4. The BRS was much lower in 2K1C rats than in sham-operated rats (-1.53±0.24beats·min^-1·mmHg^-1 vs.-3.15±0.54 beats·min^-1·mmHg^-1, P<0.05). Stimulation of the ADN with the chip system significantly increased the BRS in 2K1C rats, but not in sham-operated rats. However, the BRS was still much lower in 2K1C rats than in sham-operated rats during the stimulation of the chip system (-1.94±0.30 beats·min^-1·mmHg^-1 vs. -3.47±0.49 beats·min^-1·mmHg^-1, P<0.05).5. There was no significant change in plasma renin concentration in 2K1C rats during the stimulation of the chip system （4.03±0.6ng/ml vs. 4.88±0.8 ng/ml, P>0.05）.6. The LVDP and LVdP/dtmax were significantly higher in 2K1C rats than in sham-operated rats （LVDP: 172.7±9.8 mmHg vs. 131.5±9.9 mmHg, P<0.05, LVdP/dtmax: 5314.4±318.9 mmHg/sec vs. 3979.1±219.6 mm Hg/sec, P<0.05）. Stimulation with the chip system normalized the LVDP （121.1±7.9 mmHg） and LVdP/dtmax （4023.1±212.8 mmHg/sec） in 2K1C rats. The stimulation did not cause any significant effect on LVEDP in either 2K1C or sham-operated rats.The present study showed that the closed-loop chip system achieved a good anti-hypertensive effect in the acute experiment of 2K1C rats. The chip system caused a greater fall in MAP, but a smaller fall in HR in 2K1C rats than in sham-operated rats, suggesting that the depressor effect induced by the chip system was less dependent on its bradycardia effect in 2K1C rats than in sham-operated rats. The stimulation with the chip system decreased the enhanced sympathetic outflow in 2K1C rats. The plasma norepinephrine concentration was much higher in 2K1C rats than in sham-operated rats, the chip system regulation normalized the plasma norepinephrine concentration in 2K1C rats; The BRS was improved during the chip resetting in 2K1C rats, which might be explained that the chip system strengthened the baroreflex by establishing a closed-loop control system and there was no significant difference in the BRS before and after the chip resetting, which indicated the activation of baroreflex didn’t affect the baroreflex function in 2K1C rats in the acute experiment. There was no significant change in plasma renin concentration in 2K1C rats during the stimulation of the chip system. The stimulation of ADN with the chip system normalized the LVDP and LVdP/dt in 2K1C rats, indicating that the stimulation with the chip system decreased the cardiac contractility. During the stimulation, the LVDP, LVEDP and LVdP/dt in either 2K1C rats or sham-operated rats were in normal range, suggesting that the application of the chip system did not cause obvious hemodynamic abnormalities.In conclusion, the chip system could effectively control blood pressure in2K1C rats in the acute experiment. It improves the baroreflex sensitivity,normalizes the enhanced sympathetic activity and the plasmanorepinephrine concentration as well as the cardiac contractile state in2K1C rats.更多还原