【作者】 孙娇；

【导师】 李亘松；

【作者基本信息】 中国医科大学 ， 生理学， 2008， 硕士

【摘要】 前言在窦性心律的一定时间内,这种逐次心动周期之间的时间变异数即为心率变异性(heart rate variability,HRV)。产生心率波动的因素非常复杂,包括脑的高级神经活动、中枢神经系统的自发性节律活动、呼吸活动以及由压力、化学感受器导入的心血管反射活动等。临床医学还证明:急性心肌梗塞、心脏病患者的猝死、充血性心衰、高血压、冠心病等心血管疾病,甚至糖尿病患者的HRV都较正常人有显著的降低。由此可见,HRV的研究对心血管疾病的早期诊断、病中监护及预后评估有重要意义。岛叶是控制交感神经和副交感神经介导的心血管调节最重要的皮层区域,岛叶损伤会引起一系列心率变异性参数的变化,包括SDNN,RMSSD降低,LF/HF升高以及夜间平均心率明显增加,血清去甲肾上腺素水平升高和QT间期延长以及复杂的心律失常,甚至猝死。这些现象均说明岛叶损伤可以引起交感—迷走神经平衡失调,进而出现病理性交感神经激活。预适应现象(Preconditioning,PC)是指机体或者组织预先受到轻微的刺激或者损伤后,对后期较强的刺激或损伤产生耐受的现象。预适应原理可以使我们针对不同的应激采用合适的措施来提高自身对应激的适应性,以防范应激产生的伤害效应。本实验通过观察岛叶接受电刺激及预刺激后大鼠HRV的改变及其频谱成份的变化,来判断电刺激及预刺激在大鼠HRV调节中的作用。实验方法健康雄性Wistar大鼠40只,体重250—300g,由中国医科大学实验动物中心提供。在实验前三天将大鼠置于一避音房间,给予12h:12h光照—黑暗周期(早8:00—20:00光照),保持室温24±2℃,湿度(55±5)%。大鼠单笼饲养,自由进食、水,在实验中随机分组。测量心电图前三天让大鼠在实验室适应1—2小时。随机抽取10只大鼠,采用针形电极给予500μA电流20分钟,作为500μA组。随机抽取10只大鼠,采用针形电极给予1000μA电流20分钟,作为1000μA组。随机抽取10只大鼠,在给予1000μA电刺激前,给予50μA电流20分钟,作为预刺激组。随机抽取10只大鼠采用上述方法插入电极,但是不通电流,作为假手术对照组。然后分别测量各组ECG,用随机附带的分析软件分析HRV,得到HRV各指标的数据。数据用SPSS软件处理。实验结果500μA组同假手术组相比较HRV时域指标中SDNN(P＜0.05);RMSSD(P＞0.05)下降;频域指标中TP(P＜0.05)下降;而LF/HF升高(P＜0.01)。1000μA组同假手术组相比较HRV时域指标中SDNN(P＜0.05),RMSSD(P＞0.05)下降;频域指标中TP(P＜0.05)下降;而LF/HF升高(P＜0.01)。预刺激组SDNN(P＜0.01),RMSSD(P＜0.05),TP(P＜0.05),LF/HF(P＞0.05)均升高,且LF/HF升高幅度不及1000μA刺激组,提示预刺激可以削弱电刺激岛叶造成的交感神经活性升高。结论1、电刺激岛叶使大鼠HRV时域指标中SDNN、RMSSD下降;频域指标TP下降,但是LF/HF升高,而且这种变化是可逆的。2、电刺激岛叶可通过作用于自主神经系统,增加交感神经张力,降低迷走神经张力,使交感和迷走神经功能失调而使HRV降低。3、预刺激可以减轻电刺激对HRV的影响,并且使HRV参数值较快恢复正常。更多还原

【Abstract】 IntroductionHeart rate variability(HRV)is the time variance of sinus beat-to-beat in a period of time.Producing the heart rate undulates of the factors are very complicated, including senior nervous activity of brain,the central nervous system spontaneity rhythm,breathing activity and the activity reflecting from pressure,chemistry receptor leading-in cardiovascular system very much.Clinical medicine is testified:The impatient with myocardial infarction,sudden death of heart disease,the congestion heart failure,cardiovascular diseases such as hypertension,coronary heart disease, even the diabetes has notable lessening HRV.It can be seen from it that the HRV research appraises cardiovascular disease early phase diagnose,disease middle guardianship and prognosisThe insular is the important cortex area to control sympathetic and parasympathetic nerve mediating cardiovascular activities and its injure can change a series of HRV parameter,includeing SDNN,RMSSD lessening,LF/HF rising,average pulses increasing by obviously at night,serum noradrenaline level increasing,QT interval prolonging,complicated arrhythmia and sudden death.These phenomena explain that insular loss can arouse sympathetic-parasympathetic nerve losing balance,then appearing pathological sympathetic nerves to activate.Preconditioning is refer to organism or organ after suffering the slight stimulation or loss in advance, the stimulation or loss creats comparatively stronger bearing to later stage.Principle of preconditioning can make us activate hurting adoption to improve oneself corresponding exciting adaptability in right measure,in order to prevent the output injury effect.The experiment observes the effect of electric stimulation and prestimulation to the insular on HRV and frequency spectrum component,judging the contribution of electric stimulation and prestimulation to HRV in rat.Materials and MethodsAdult male Wistar rat(250—300)g,obtained from the Experimental Animal Center of China Medical University,were used in this study.Three days before the experiment,each rat was placed in a rat-box without restraint for 1-2h to adapt the experiment in a room without noise,light and darkness were alternated with light 8:00 to 20:00.The ambient temperature of animal room was(24±2)℃,and the humidity (55±5)%.Animals were caged individually and free access to food and water.The rats were divided randomly into four groups:control group,500μA group, 1000μA group,preconditioning group.10 rabbits randomly selected were given 500μA current,20 minutes,as 500μA group.10 rabbits randomly selected were given 1000μA current,20 minutes,as 1000μA group.10 rabbits randomly selected were given 50μA current,20 minutes,before given 1000μA current,20 minutes,as preconditioning group.10 rabbits randomly selected were inserted electrode,20 minutes,without current,as control group.Results500μA group,the SDNN(P＜0.05)and RMSSD of time domain decreased significantly,TP(P＜0.05)frequency domain decreased significantly,LF/HF increased significantly(P＜0.01),compared with the control group;1000μA group, the SDNN(P＜0.05)and RMSSD of time domain decreased significantly,TP(P＜0.05)frequency domain decreased significantly,LF/HF increased significantly (P＜0.01),compared with the control group compared with the control group; Prestimulation group,SDNN(P＜0.01),RMSSD(P＜0.05),TP(P＜0.05),LF/HF frequency domain increased significantly,compared with 1000μA group,the activity pointing out that the prestimulation can weaken the electrical stimulation of autonomic nerves that the insular brings about.Conclusion1.The electricity stimulation used in the insular of rat makes HRV time domain index SDNN,RMSSD comes down,frequency domain index TP comes down,but LF/HF rises,and this change is reversible.2.The electricity stimulation used in the insular of rat increases sympathetic nerves tension,reduces parasympathetic nerve tension,makes sympathiaparasympathetic nerve functional disturbance,and HRV lessening by the effect of autonomic nervours system.3.The prestimulation can lighten an impact of electricity stimulation over HRV in advance,and makes the HRV parameter return to normal comparatively quickly.更多还原