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

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）。Ｌ     

电刺激大鼠隔后部对血压和心率的影响及其下行通路

心血管中枢广泛分布在脊髓至大脑皮层的各级水平。其中边缘系统对心血管活动的调节作用显得更为突出。隔后部(CS)是边缘系统成员之一。缰核(Hb)是前脑边缘结构至脑干的驿站,前脑边缘结构的许多部位都有纤维会聚到Hb,CS就是其中之一。本实验室已证明     

迷走神经兴奋性对HRV的影响及其机制的初步分析

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,心电图和心率变异性频谱分析。电刺激减压神经,疑核和右侧迷走神经外周端,均引起心率和血压下降,总变异性,低频成分,高频成分,ＬＦ／ＨＦ比值和极代频成分增大。静脉注射阿托品可使上述反应显著减小,而静脉注射心得安仅可阻断ＤＮ和ＮＡ所致ＬＦ的增大。     

电刺激迷走神经对大鼠脑缺血后轴突再生及RGMa表达的影响

本研究拟探讨电刺激迷走神经对大鼠脑缺血/再灌注(I/R)损伤后轴突再生和排斥性导同因子A(RGMa)蛋白表达的影响.首先,准备成年雄性SD (Sprague-Dawley)大鼠36只,并随机分成假手术组(Sham组)、脑缺血/再灌注组(I/R组)和迷走神经电刺激组(I/R+VNS组).随后,构建大脑中动脉阻塞(MCAO...     

迷走神经刺激对记忆的影响

迷走神经刺激(vagus nerve stimulation, VNS)用于终止癫痫发作已经有二十年的历史.期间VNS也用于难治性抑郁的治疗.在治疗过程中研究者发现VNS 对癫痫、抑郁患者的学习和记忆能力有改善作用,这种改善作用在一些动物和人体实验中也得到证实.但VNS在记忆形成的哪个阶段起作用以及如何起作用的具体机制尚不十分清楚.因此,进一步了解VNS对记忆的影响及作用机制有利于探讨记忆形成的生理机制,也为临床治疗特异性记忆障碍和相关神经精神疾病提供新的思路和有益补充.本文综述了近十几年来VNS对记忆的影响及相关机制.     

迷走神经兴奋对HRV的影响及其机制的初步分析

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、心电图和心率变异性（ＨＲＶ）频谱分析。电刺激减压神经（ＤＮ）,疑核（ＮＡ）和右侧迷走神经（ＲＶ）外周端,均引起心率和血压下降（Ｐ＜０．００１）,总变异性（ＴＶ）、低频成分（ＬＦ）、高频成分（ＨＦ）、ＬＦ／ＨＦ比值（ＬＦ／ＨＦ）和极低频成分（ＶＬＦ）增大（Ｐ＜０．０５－０．００１）。静脉注射阿托品可使上述反应显著减小（Ｐ＜０．０５－０．０１）,而静脉注射心得安仅可阻断ＤＮ和ＮＡ所致ＬＦ的增大（Ｐ＜０．０５）。以上结果表明：迷走神经是ＨＲＶ的主要调节者之一;ＨＦ由迷走神经单独介导;ＬＦ受迷走神经和交感神经共同调制;迷走神经参与ＶＬＦ波的形成     

基于心率变异性引导的阿尔茨海默病磁刺激干预技术研究

目的 无创磁刺激技术已广泛应用于阿尔茨海默病 （Alzheimer’s disease, AD） 的治疗,但缺乏便捷及时的疗效评估与反馈方法,难以有效指导磁刺激方案的调整。本研究旨在探究心率变异性（heart rate variability,HRV）诊断AD并引导AD磁刺激干预技术的可能性。方法 本研究采用频率40 Hz、磁感应强度10 mT的脉冲磁场对AD模型小鼠进行为期18 d的全身暴露实验,检测暴露前后的行为学和心脑电信号,并采集每天暴露后的即时心电信号。结果 利用单因素方差分析与皮尔逊相关系数分析发现：HRV部分指标可以和行为学及脑电（electroencephalogram,EEG）一样精确识别AD模型小鼠 （P<0.05）并显著区分病症程度（P<0.05）,其中rMSSD、pNN6、LF/HF、SD1/SD2及排列熵展现出了与行为学及脑电良好的相关性及统计学意义（r>0.3,P<0.05）;磁场暴露前后这些HRV指标同行为学及脑电均得到显著调节（P<0.05）,且在连续的心电变化中更精确地观察到刺激效果的变化趋势。结论 HRV能精确反映病理生理变化和病症程度,快速评估磁刺激效果,具有用于引导曝磁模式的潜力,为研究脑疾病的个性化电磁神经调控技术提供了新思路。     

电刺激兔大脑皮层对呼吸频率和幅度的影响

本工作用家兔３８只,麻醉并切断双侧迷走神经和三叉神经上颌支,观察连续刺激大脑皮层不同区域对呼吸的影响。结果：１．适度的电刺激：（１）对肢体运动区（Ｌ）,使吸气加强,呼吸频率（ＲＦ）和潮气量（ＴＶ）均显著增加;（２）对颜面运动区（Ｆ）,使ＲＦ显著增加,但呼气和吸气均被抑制,ＴＶ显著降低;（３）对咀嚼运动区（Ｍ）,出现间歇性吸气或呼气加强,ＲＦ和ＴＶ均明显增加;（４）对眶后区（ＰＯ）,使ＲＦ和ＴＶ均显     

不周浓度乙醇对蟾蜍血压和心率的影响

本实验采用静脉内注入乙醇的方法,观察了不同浓度乙醇对蟾蜍血压和心率的影响。结果表明：尽管乙醇浓度不同,但大多数注入乙醇后血压降低,少数升高;心率大多数变慢,少数加快或不变。随着乙醇浓度升高,这种现象仍然存在。提示动物种类和个体差异,对乙醇反应也是不同的。     

电刺激大鼠蓝斑核区对实验性急性心肌缺血性损伤的影响

本实验在大鼠尾静脉注射垂体后叶素造成急性心肌缺血性损伤,以心电图肢体导联 S-T_Ⅱ段和 T_Ⅱ以及心率为指标,观察了电刺激蓝斑核区对大鼠急性心肌缺血性损伤的影响。实验结果表明蓝斑核区电刺激组的缺血性心电图恢复时间与对照组相比显著提前,前者为18.8±8.31分,后者为67±12.74分(P<0.01)。脑非蓝斑核区电刺激组的缺血性心电图恢复时间为69.2±6.8分。蓝斑核埋藏电极组的恢复时间为44.5±9.97分,与蓝斑核区电刺激组相比,其差异均非常显著(P<0.01)。这些结果说明蓝斑核区的刺激对大鼠急性心肌缺血性模型的恢复有促进作用。     

血管紧张素Ⅱ对家兔心率变异的影响

目的:研究血管紧张Ⅱ(AngⅡ)对家兔心率变异(HRV)影响的机制。方法:分别给家兔静脉输注生理盐水,AngⅡ,溴化六烃季胺(HEXB),HEXB+AngⅡ检测安静状态下连续5 min的心电图并进行HRV的时域和频域分析。结果:血管紧张素Ⅱ组的时域指标SDNN和RMSSD较对照组明显降低,频域指标低频(LF)升高,而高频(HF)和总功率(TP)明显降低;HEXB+AngⅡ组与HEXB组相比无明显区别。结论:交感神经阻断剂HEXB不能影响AngⅡ的作用,AngⅡ主要通过抑制中枢自主神经的传出,降低迷走神经张力来降低HRV。     

糖尿病植物神经病变病人心率变异的非线性定量分析

目的：研究糖尿病人植物神经病变与心率变异的关系。对象：正常对照组和根据临床有无糖尿病神经病变（ＤＡＮ）分组的糖尿病病人,方法：应用２４小时动态心电图对正常和糖尿病人进行心率变异的线性,非线性散点图和非线性定量参数分析,结果：单纯糖尿病组ＳＤＮＮ,ＳＤＡＮＮ和ＰＮＮ５０低于正常组（Ｐ〈０．０５）;糖尿病＋ＤＡＮ组各项线性时域分析指标均低于正常和单纯糖尿病组（Ｐ〈０．０１－０．００１）,散点图分析结果     

Effects of long-term microgravity exposure in space on circadian rhythms of heart rate variability

We evaluated their circadian rhythms using data from electrocardiographic records and examined the change in circadian period related to normal RR intervals for astronauts who completed a long-term (≥6-month) mission in space. The examinees were seven astronauts, five men and two women, from 2009 to 2010. Their mean?±?SD age was 52.0?±?4.2 years (47–59?yr). Each stayed in space for more than 160 days; their average length of stay was 172.6?±?14.6 days (163–199 days). We conducted a 24-h Holter electrocardiography before launch (Pre), at one month after launch (DF1), at two months after launch (DF2), at two weeks before return (DF3), and at three months after landing (Post), comparing each index of frequency-domain analysis and 24-h biological rhythms of the NN intervals (normal RR intervals). Results show that the mean period of Normal Sinus (NN) intervals was within 24?±?4?h at each examination. Inter-individual variability differed among the stages, being significantly smaller at DF3 (Pre versus DF1 versus DF3 versus Post?=?22.36?±?2.50 versus 25.46?±?4.37 versus 22.46?±?1.75 versus 26.16?±?7.18?h, p?<?0.0001). The HF component increased in 2 of 7 astronauts, whereas it decreased in 3 of 7 astronauts and 1 was remained almost unchanged at DF1. During DF3, about 6 months after their stay in space, the HF component of 5 of 7 astronauts recovered from the decrease after launch, with prominent improvement to over 20% in 3 astronauts. Although autonomic nervous functions and circadian rhythms were disturbed until one month had passed in space, well-scheduled sleep and wake rhythms and meal times served as synchronizers.     

大鼠心率变异性频谱中高频成分的中枢机理分析

本文探讨心率变异性（ＨＲＶ）频谱中高频成分的中枢机理。对正常ＳＤ大量给予不同频率的人工通气并电刺激延髓疑核,观察ＨＲＶ频谱的改变,记录与呼吸节律同步的延髓头端腹外侧区（ｒＶＬＭ）及其周围区神经元细胞外单位放电,对ＨＲＶ和放电变异性进行相干函数分析。结果显示：（１）ＨＲＶ的高频成分的中心频率随着人工通气频率的增加而增加,呈高度线性相关,（ｒ＝０．８３,Ｐ〈０．０００１）;（２）对ｒＶＬＭ及其周围区与     

Determination of heart rate and heart rate variability in the equine fetus by fetomaternal electrocardiography

Heart rate is an important parameter of fetal well-being. We have analyzed fetal heart rate (HR) and heart rate variability (HRV) by fetomaternal electrocardiography (ECG) in the horse (Equus caballus) from midpregnancy to foaling. It was the aim of the study to detect changes in the regulation of fetal cardiac activity over time and to establish normal values in undisturbed pregnancies. A total of 22 mares were available for the study. Fetomaternal electrocardiography was a reliable technique to detect cardiac signals in fetuses between Day 173 of gestation and foaling. Fetal HR decreased from 115 ± 4 beats/min (Days 170 to 240 of gestation) to 83 ± 3 beats/min (Day 320) to 79 ± 1 beats/min (1 d before foaling; P < 0.001). Mean beat to beat (RR) interval and standard deviation of the RR interval (SDRR) increased (P < 0.001). Gestational age thus affects RR interval and HR in the equine fetus. From Days 270 to 340 of gestation, SDRR increased from 11.4 ± 1.3 msec on Day 270 to 27.8 ± 3.6 msec on Day 340 (P < 0.05), and the root mean square of successive RR differences (RMSSD) tended to increase (P = 0.07), indicating maturation of the fetal autonomous nervous system. For the last 10 d before foaling, fetal HR and HRV remained constant and did not allow predicting the onset of parturition in the horse. Only during the last 30 min before the foal was born, in 4 of 5 fetuses, HR decreased and RR interval increased. Accelerations and decelerations in HR were detectable at all times, but neither their number nor duration changed over time.     

Normative references of heart rate variability and salivary alpha-amylase in a healthy young male population

Background

This study aimed to present normative reference values of heart rate variability and salivary alpha-amylase in a healthy young male population with a particular focus on their distribution and reproducibility.

Methods

The short-term heart rate variability of 417 young healthy Japanese men was studied. Furthermore, salivary alpha-amylase was measured in 430 men. The average age of the subjects were 21.9 years with standard deviation of 1.6 years. Interindividual variations in heart rate variability indices and salivary alpha-amylase levels were plotted as histograms. Data are presented as the mean, median, standard deviation, coefficient of variation, skewness, kurtosis, and fifth and 95th percentiles of each physiological index.

Results

Mean recorded values were heart period 945.85 ms, log-transformed high frequency component 9.84 ln-ms², log-transformed low frequency component 10.42 ln-ms², log-transformed low frequency to high frequency ratio 0.58 ln-ratio, standard deviation of beat-to-beat interval 27.17 ms and root mean square of successive difference 37.49 ms. The mean value of raw salivary alpha-amylase was 17.48 U/mL, square root salivary alpha-amylase 3.96 sqrt[U/mL] and log-transformed salivary alpha-amylase 2.65 ln[U/mL]. Log-transformed heart rate variability indices exhibited almost symmetrical distributions; however, time-domain indices of heart rate variability (standard deviation of beat-to-beat interval and root mean square of successive difference) exhibited right-skewed (positive skewness) distributions. A considerable right-skewed distribution was observed for raw salivary alpha-amylase. Logarithmic transformation improved the distribution of salivary alpha-amylase, although square root transformation was insufficient. The day-to-day reproducibility of these indices was assessed using intraclass correlation coefficients. Intraclass correlation coefficients of most heart rate variability and salivary indices were approximately 0.5 to 0.6. Intraclass correlation coefficients of raw salivary markers were approximately 0.6, which was similar to those of heart rate variability; however, log transformation of the salivary markers did not considerably improve their reproducibility. Correlations between sympathetic indicators of heart rate variability and salivary alpha-amylase were not observed.

Conclusion

Because the sample population examined in this study involved limited age and gender variations, the present results were independent of these factors and were indicative of pure interindividual variation.     

Blood pressure and heart rate variability are linked with hyperphosphatemia in chronic kidney disease patients

ABSTRACT

Hyperphosphatemia is a common complication of chronic kidney disease (CKD) and is associated with cardiovascular disease (CVD), which has contributed to an increase in mortality of CKD patients. The onset of CVD often varies by time-of-day. Acute myocardial infarction or ventricular arrhythmia occurs most frequently during early morning. Blood pressure (BP) and heart rate circadian rhythms account for the diurnal variations in CVD. Preservation of normal circadian time structure from the cardiomyocyte level to the whole organ system is essential for cardiovascular health and CVD prevention. Independent risk factors, such as reduced heart rate variability (HRV) and increased BP variability (BPV), are particularly prevalent in patients with CKD. Analysis of HRV is an important clinical tool for characterizing cardiac autonomic status, and reduced HRV has prognostic significance for various types of CVD. Circadian BP rhythms are classified as extreme dipper, dipper, non-dipper or riser. It has been reported that nocturnal riser BP pattern contributes to cardiovascular threats. Previous studies have indicated that the circadian rhythm of serum phosphate in CKD patients is consistent with the general population, with the highest diurnal value observed in the early morning hours, followed by a progressive decrease to the lowest value of the day, which occurs around 11:00 am. Rhythm abnormalities have become the main therapeutic target for treating CVD in CKD patients. It has been reported that high levels of serum phosphate are associated with reduced HRV and increased BPV in CKD patients. However, the mechanisms related to interactions between hyperphosphatemia, HRV and BPV have not been fully elucidated. This review focuses on the evidence and discusses the potential mechanisms related to the effects of hyperphosphatemia on HRV and BPV.     

Changes in cortisol release and heart rate and heart rate variability during the initial training of 3-year-old sport horses

Based on cortisol release, a variety of situations to which domestic horses are exposed have been classified as stressors but studies on the stress during equestrian training are limited. In the present study, Warmblood stallions (n = 9) and mares (n = 7) were followed through a 9 respective 12-week initial training program in order to determine potentially stressful training steps. Salivary cortisol concentrations, beat-to-beat (RR) interval and heart rate variability (HRV) were determined. The HRV variables standard deviation of the RR interval (SDRR), RMSSD (root mean square of successive RR differences) and the geometric means standard deviation 1 (SD1) and 2 (SD2) were calculated. Nearly each training unit was associated with an increase in salivary cortisol concentrations (p < 0.01). Cortisol release varied between training units and occasionally was more pronounced in mares than in stallions (p < 0.05). The RR interval decreased slightly in response to lunging before mounting of the rider. A pronounced decrease occurred when the rider was mounting, but before the horse showed physical activity (p < 0.001). The HRV variables SDRR, RMSSD and SD1 decreased in response to training and lowest values were reached during mounting of a rider (p < 0.001). Thereafter RR interval and HRV variables increased again. In contrast, SD2 increased with the beginning of lunging (p < 0.05) and no changes in response to mounting were detectable. In conclusion, initial training is a stressor for horses. The most pronounced reaction occurred in response to mounting by a rider, a situation resembling a potentially lethal threat under natural conditions.     

Cortisol release and heart rate variability in horses during road transport

Based on plasma cortisol concentrations it is widely accepted that transport is stressful to horses. So far, cortisol release during transport has not been evaluated in depth by non-invasive techniques such as analysis of salivary cortisol and faecal cortisol metabolites. Transport also causes changes in heart rate and heart rate variability (HRV). In this study, salivary cortisol, faecal cortisol metabolites, heart rate and HRV in horses transported by road for short (one and 3.5 h) and medium duration (8 h) were determined. With the onset of transport, salivary cortisol increased immediately but highest concentrations were measured towards the end of transport (4.1 ± 1.6, 4.5 ± 2.6, 6.5 ± 1.8 ng/ml in horses transported for one, 3.5 and 8 h, respectively). Faecal cortisol metabolite concentrations did not change during transport, but 1 day after transport for 3.5 and 8 h had increased significantly (p < 0.01), reflecting intestinal passage time. Compared to salivary cortisol, changes in faecal cortisol metabolites were less pronounced. Heart rate increased and beat-to-beat (RR) interval decreased (p < 0.05) with the onset of transport. Standard deviation of heart rate increased while root mean square of successive RR differences (RMSSD) decreased in horses transported for 3.5 (from 74 ± 5 to 45 ± 6 ms) and 8 h (from 89.7 ± 7 to 59 ± 7 ms), indicating a reduction in vagal tone. In conclusion, transport of horses over short and medium distances leads to increased cortisol release and changes in heart rate and HRV indicative of stress. The degree of these changes is related to the duration of transport. Salivary cortisol is a sensitive parameter to detect transient changes in cortisol release.