最后区注射腺苷对大鼠血压、心率和肾交感神经放电的影响

在 5 3只麻醉Sprague Dawley大鼠观察了最后区内微量注射腺苷 (1ng/ 6 0nl)对平均动脉压 (MAP)、心率(HR)和肾交感神经放电 (RSNA)的影响。实验结果如下 :(1)最后区内微量注射Ado后 ,MAP、HR和RSNA分别由13 76± 0 46kPa、35 6 2 8± 4 2 5bpm和 10 0± 0 %下降至 11 2 3± 0 49kPa (P <0 0 0 1)、336 91± 5 2 3bpm (P <0 0 1)和70 95± 5 19% (P <0 0 0 1) ;(2 )静脉注射非选择性腺苷受体拮抗剂 8 苯茶碱 (8 phenyltheophylline,15 0 μg/kg ,0 2ml)和选择性腺苷A1受体拮抗剂 (8 cyclopentyl 1,3 dipropylxanthine,5 0 0 μg /kg ,0 2ml)后 ,腺苷的上述抑制效应可被完全阻断 ;(3)静脉注射ATP敏感性钾通道阻断剂格列苯脲 (5mg/kg ,0 2ml)后 ,腺苷的上述效应也被消除。以上结果提示 ,最后区微量注射腺苷对血压、心率和肾交感神经放电有抑制作用 ,此作用与A1受体介导的ATP敏感性钾通道开放有关。     

颈动脉注射腺苷对去缓冲神经大鼠延髓腹外侧头端区神经元放电的影响

在28只切断双侧缓冲神经的Sprague－Dawley大鼠,应用细胞外记录方法,观察了72个自发放电单位中颈动脉注射腺苷对延髓腹外侧头端（RVLM）区神经元自发放电活动的影响。所得结果如下：（1）颈动脉注射腺苷（25μg/kg）,31个单位的放电频率由23．5±3．0下降至（16．5±2．6）spikes／s（P＜0．001）,血压和心率无明显变化（P＞0．05）;（2）在24个单位中,应用非选择性腺苷受体拮抗剂8-苯茶碱（8-phenyltheophylline,15μg/kg）和选择性腺苷A1受体持抗剂8-环戊-1,3-二丙基黄嘌呤（8－cyclopentyl-1,3－dipropylxanthine,50μg/kg）均可完全阻断腺苷的抑制效应;（3）在应用ATP敏感性钾通道阻断剂格列苯脲（500μg/kg）的12个单位中,腺苷的上述效应亦被消除。以上结果提示,腺苷对RVLM区神经元自发放电有抑制作用,而此作用与A1受体介导的ATP敏感性钾通道开放有关。     

电刺激迷走神经对蟾蜍心率和心率变异的影响

目的:观察不同频率迷走神经刺激对蟾蜍离体心脏的心率及心率变异的影响。方法:将蟾蜍心脏和右侧迷走交感干离体后,以不同频率电刺激神经,记录心电图曲线并作心率变异性(HRV)分析。结果:交感神经阻断后,电刺激迷走交感干,心率(HR)显著下降(P0.01),全部正常心动周期的标准差(SDNN)和相邻正常心动周期差值的均方根(RMSSD)显著升高(P0.01),不同频率刺激组之间没有明显差异;与对照组相比,各指标变化较大;给药组0.2Hz时高频(HF)显著升高(P0.01),低频/高频比值(LF/HF)明显降低(P0.05),0.8Hz时HF和LF/HF接近刺激前水平。结论:一定范围内增加刺激频率,迷走神经降低心率的作用增强;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。     

The relationship of the slope of the heart rate graph regression with linear and nonlinear heart rate dynamics in stationary short-time series

The relationship of the slope of the heart rate graph regression curve (b ₁) with periodic (linear) and nonlinear heart rate dynamics has been studied in stationary short-time series (256 points). For estimating nonlinear dynamics, a parameter derived from correlation dimension has been used, which has made it possible to estimate chaotic processes in short-time series. According to the results of the study, the heart rate dynamics in short-time series may be represented as a sum of linear (periodic) and nonlinear (stochastic) processes. The relationships of b ₁ with both the linear and the nonlinear heart rate dynamics have been demonstrated. Equations for calculating the absolute and relative (to the periodic oscillation amplitude) noises in the heart rate dynamics in short-time series are proposed. Stochastic nonlinear dynamics in different physiological states of humans have been compared. It has been found that the increase in the relative noise intensity in the heart rate dynamics with an increase in respiration rate is determined not only by the decrease in the amplitude of respiratory waves, but also by an increase in the amplitude of the noise itself. The absolute noise intensity is decreased in the states of neurotic excitement, fatigue, and, especially, mental stress. In the state of rest, nonlinear (stochastic) processes dominate over linear (periodic) ones.     

A mathematical model of human heart including the effects of heart contractility varying with heart rate changes

Incorporating the intrinsic variability of heart contractility varying with heart rate into the mathematical model of human heart would be useful for addressing the dynamical behaviors of human cardiovascular system, but models with such features were rarely reported. This study focused on the development and evaluation of a mathematical model of the whole heart, including the effects of heart contractility varying with heart rate changes. This model was developed based on a paradigm and model presented by Ottesen and Densielsen, which was used to model ventricular contraction. A piece-wise function together with expressions for time-related parameters were constructed for modeling atrial contraction. Atrial and ventricular parts of the whole heart model were evaluated by comparing with models from literature, and then the whole heart model were assessed through coupling with a simple model of the systemic circulation system and the pulmonary circulation system. The results indicated that both atrial and ventricular parts of the whole heart model could reasonably reflect their contractility varying with heart rate changes, and the whole heart model could exhibit major features of human heart. Results of the parameters variation studies revealed the correlations between the parameters in the whole heart model and performances (including the maximum pressure and the stroke volume) of every chamber. These results would be useful for helping users to adjust parameters in special applications.     

Welfare implication of measuring heart rate and heart rate variability in dairy cattle: literature review and conclusions for future research

Heart rate (HR) measurements have been used to determine stress in livestock species since the beginning of the 1970s. However, according to the latest studies in veterinary and behaviour–physiological sciences, heart rate variability (HRV) proved to be more precise for studying the activity of the autonomic nervous system. In dairy cattle, HR and HRV indices have been used to detect stress caused by routine management practices, pain or milking. This review provides the significance of HR and HRV measurements in dairy cattle by summarising current knowledge and research results in this area. First, the biological background and the interrelation of the autonomic regulation of cardiovascular function, stress, HR and HRV are discussed. Equipment and methodological approaches developed to measure interbeat intervals and estimate HRV in dairy cattle are described. The methods of HRV analysis in time, frequency and non-linear domains are also explained in detail emphasising their physiological background. Finally, the most important scientific results and potential possibilities for future research are presented.     

The limitations of heart rate as a predictor of metabolic rate in fish

Although telemetered heart rate (f_H) has been used as a physiological correlate to predict the metabolic rate (as oxygen consumption, V?O₂) of fish in the field, it is our contention that the method has not been validated adequately for fish. If f_H in fish is to be used to estimate V?O₂, a single linear (or log-linear) relationship must be established for each species between the two variables which allows V?O₂ to be predicted accurately under all environmentally relevant conditions. Our analyses of existing data indicate that while a good linear (or log-linear) relationship can be established between f_H and V?O₂, the conditions under which the relationship applies may be quite restricted. Physiological states and environmental factors affect the relationship between f_H and V?O₂ significantly such that several curves can exist for a single species. In addition, there are situations in which f_H and V?O₂ do not covary in a significant manner. In some situations f_H can vary over much of its physiological range while V?O₂ remains constant; in others V?O₂ may vary while f_H is invariate. The theoretical basis for this variability is examined to explain why the use of telemetered f_H in predicting V?O₂ of fish may be limited to certain specified applications.     

A simple assay of solubilized adenosine receptors with nitrocellulose membrane filters

A rapid and simple assay of solubilized adenosine receptors with nitrocellulose membrane filters is described. This assay was sensitive and reproducible when applied to adenosine receptors solubilized from rat brainstem membranes with 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate. Appropriate values of dissociation constants for the solubilized adenosine receptors to their tritiated agonists were obtained by the membrane filter technique. This method should be applicable for the assay of a variety of solubilized receptors.     

Modulation of adenosine A1 and A2A receptors in C6 glioma cells during hypoxia: involvement of endogenous adenosine

During hypoxia, extracellular adenosine levels are increased to prevent cell damage, playing a neuroprotective role mainly through adenosine A₁ receptors. The aim of the present study was to analyze the effect of hypoxia in both adenosine A₁ and A_2A receptors endogenously expressed in C6 glioma cells. Two hours of hypoxia (5% O₂) caused a significant decrease in adenosine A₁ receptors. The same effect was observed at 6 h and 24 h of hypoxia. However, adenosine A_2A receptors were significantly increased at the same times. These effects were not due to hypoxia-induced alterations in cells number or viability. Changes in receptor density were not associated with variations in the rate of gene expression. Furthermore, hypoxia did not alter HIF-1α expression in C6 cells. However, HIF-3α, CREB and CREM were decreased. Adenosine A₁ and A_2A receptor density in normoxic C6 cells treated with adenosine for 2, 6 and 24 h was similar to that observed in cells after oxygen deprivation. When C6 cells were subjected to hypoxia in the presence of adenosine deaminase, the density of receptors was not significantly modulated. Moreover, DPCPX, an A₁ receptor antagonist, blocked the effects of hypoxia on these receptors, while ZM241385, an A_2A receptor antagonist, was unable to prevent these changes. These results suggest that moderate hypoxia modulates adenosine receptors and cAMP response elements in glial cells, through a mechanism in which endogenous adenosine and tonic A₁ receptor activation is involved.     

侧脑室及下丘脑视前区微量注射孤啡肽对大鼠血压、心率的影响

孤啡肽（OrphaninFQ,OFQ）是1995年底发现的内阿片肽,一级结构与强啡肽A很相似,但生物学作用与其它内阿片肽有所不同。本工作采用侧脑室及核团微量注射的方法,观察了中枢OFQ对大鼠心血管活动的影响。结果表明：侧脑室注射1、10μgONQ可明显降低大鼠平均动脉压（MAP）及心率（HR）;侧脑室预先注射4μg纳洛酮不影响1μgOWQ的降压及减慢心率的效应。下丘脑视前区（POA）微量注射1μgOFQ也可降低血压、减慢心率。结果表明,中枢OFQ与其它内阿片肽相似,可抑制心血管活动,且其抑制作用不是通过μ、δ、κ阿片受体介导。POA为中枢OFQ抑制心血管活动的靶区之一。     

正常人和无睡眠呼吸异常慢病患者睡眠期间的呼吸源性心率变异初步报告*

目的: 整体整合生理学医学新理论-呼吸循环代谢等系统一体化调控提出了呼吸为循环指标变异性起源的假说,我们对人睡眠期间的呼吸和心率变异分别分析,探索心率变异的起源。方法: 本研究回顾性分析了2014年以来行心肺运动试验（CPET）、多导睡眠图（PSG）鼻气流和心电图监测的8例无疾病诊断的正常人和10例无睡眠呼吸异常的慢性疾病患者,分析夜晚睡眠期间鼻气流的呼吸周期与心电图R-R间期心率变异周期的关系。一个完整的呼吸周期包括吸气过程和紧接着的呼气过程,分析计算呼吸周期数、平均呼吸周期时间等指标。心率由心电图的R-R间期计算获得,连续一次心率由最低点上升至最高点,再由最高点下降至最低点,为一个心率变异周期,计算心率变异周期数、平均心率变异时间、心率变异平均幅度等指标。比较同一人呼吸和心率变异指标之间的相互关系,以及两组人群之间的异同。结果: 正常人峰值摄氧量、无氧阈等CPET核心指标均显著优于无睡眠呼吸异常的慢性疾病患者（P<0.05）。正常人AHI（（1.7±1.3）次/小时）和无睡眠呼吸异常慢性疾病患者AHI（（2.9±1.2）次/小时）无差异（P>0.05）。正常人呼吸周期数与心率变异周期数（（6581.63±1411.90）次、（6638.38±1459.46）次）、平均呼吸周期时间与平均心率变异周期时间（（4.19±0.57）s、（4.16±0.62）s）均高度一致,无差异（P>0.05）。无睡眠呼吸异常的慢性疾病患者上述指标比较（（7354.50±1443.50）次与（7291.20±1399.31）次、（4.20±0.69）s与（4.23±0.68）s）也是高度一致,无统计学差异（P>0.05）。正常人呼吸周期数/心率变异周期数（0.993±0.027）与无睡眠呼吸异常的慢性疾病患者呼吸周期数/心率变异周期数（1.008±0.024）比值均接近1。正常人心率变化平均幅度（（5.74±3.21） bpm）略高于无睡眠呼吸异常的慢性疾病患者（（2.88±1.44） bpm,P<0.05）。结论: 正常人和无睡眠呼吸异常的慢性疾病患者无论功能状态如何,心率变异与呼吸存在极其相似的一致性,其心率变异的始发因素均为呼吸所致。     

Ultra-wideband electromagnetic pulses: Lack of effects on heart rate and blood pressure during two-minute exposures of rats

Exposure to fast-rise-time ultra-wideband (UWB) electromagnetic pulses has been postulated to result in effects on biological tissue (including the cardiovascular system). In the current study, 10 anesthetized Sprague-Dawley rats were exposed to pulses produced by a Sandia UWB pulse generator (average values of exposures over three different pulse repetition rates: rise time, 174–218 ps; peak E field, 87–104 kV/m; pulse duration, 0.97–0.99 ns). Exposures to 50, 500 and 1000 pulses/s resulted in no significant changes in heart rate or mean arterial blood pressure measured every 30 s during 2 min of exposure and for 2 min after the exposure. The results suggest that acute UWB whole-body exposure under these conditions does not have an immediate detrimental effect on these cardiovascular system variables in anesthetized rats. Bioelectromagnetics 19:330–333, 1998. Published 1998 Wiley-Liss, Inc.     

Successful TRPV1 antagonist treatment for cardiac hypertrophy and heart failure in mice

Heart failure is becoming a global epidemic. It exerts a staggering toll on quality of life, and substantial medical and economic impact. In a pre-clinical model of cardiac hypertrophy and heart failure, we were able to overcome loss of heart function by administering the TRPV1 antagonist BCTC (4-(3-Chloro-2-pyridinyl)-N-[4-(1,1-dimethylethyl)phenyl]-1-piperazinecarboxamide). The results presented here identify TRPV1 antagonists as new treatment options for cardiac hypertrophy and heart failure.     

大鼠缺血性脑损伤引起学习记忆障碍及心率变异性改变

本研究通过建立高脂缺血性脑损伤大鼠模型,进行水迷宫实验和心率变异性（heart rate variability,HRV）的功率谱分析,探讨脑损伤前后大鼠学习记忆的变化及缺血对自主神经的影响。23只成年雄性Wistar大鼠随机分为对照组（n=10）、高脂组（n=6）和高脂缺血组（n=7）。高脂组和高脂缺血组大鼠均饲以高脂饲料制成高血脂大鼠模型。各组大鼠进行水迷宫实验后,高脂缺血组用双侧颈总动脉结扎（2-VO）法制作缺血再灌注模型,同时记录心电图。7d后各组大鼠再次进行水迷宫实验和记录心电图,对HRV序列进行基于快速傅立叶转换（fast Fourier transformation,FFT）的功率谱分析。结果：（1）第一次水迷宫测试,3组大鼠空间探索实验和定位航行实验结果无统计学差异;第二次水迷宫实验,高脂缺血组与其它两组相比,空间探索实验中平台所在象限的记忆频度明显下降（P〈0．01）,定位航行实验中平台所在象限的记忆频度显著下降（P〈0．01）,10圆环记忆得分显著下降（P〈0．001）,但高脂组与对照组相比无明显差异。（2）高脂缺血组缺血后心率持续下降;缺血时HRV中频段功率（0．2加．6Hz）呈现明显下降的趋势,高频段功率（0．6-2．5Hz）缓慢下降,中频／高频功率比值明显下降（P〈0．05）。（3）缺血7d后高脂缺血组与高脂组相比,心率明显加快,HRV的中频段功率无显著变化,高频段功率明显下降,中频／高频功率比值显著增高（P〈0．05）。结果表明,缺血过程中高脂缺血组大鼠的自主神经活动降低,交感神经活动相对于迷走神经活动减弱。缺血7d后,由于海马区神经元对缺血敏感易受损,造成高脂缺血组大鼠学习记忆障碍,同时引发迷走神经活动下降,大鼠交感．迷走神经系统平衡失调。     

Long-term measurement of heart rate in chicken eggs

Taking advantage of acoustocardiogram (ACG), we measured the heart rate (HR) of chick embryos continuously from day 12 until hatching and then investigated the development of HR irregularities (HRI), HR variability (HRV), and the existence of a circadian rhythm in mean HR (MHR). HRI comprised transient bradycardia and tachycardia, which first developed on day 14 and 16 in most embryos, respectively. Transient bradycardia increased in frequency and magnitude with embryonic development and occurred over periods of up to 30 min in some embryos. MHR was maximal on around days 14-15 and thereafter decreased to about 250-260 bpm on days 16-18. Baseline HRV, which is an oscillation of the MHR baseline, occurred as HR decreased from days 15-16 and became predominant on days 17-18. The magnitude of the baseline oscillations reached up to 50 bpm in some embryos and the period ranged between about 40-90 min (ultradian rhythm). A circadian rhythm of MHR was not found in late chick embryos. On days 18-19, embryonic activities were augmented and then breathing movements began to occur, disturbing ACG signals and thus making it difficult to measure the HR. Instead, the development of breathing activities was recorded. Breathing frequency was irregular at first and then increased to a maximum of about 1.5 Hz prior to hatching.     

Assessment of cardiac output as a predictor of metabolic rate in rainbow trout

When water temperature was increased from 12 to 27°C at a rate of 2°C h⁻¹, oxygen consumption of rainbow trout Oncorhynchus mykiss was correlated strongly with both heart rate and blood oxygen extraction but the relationship with cardiac output was variable and weak. On the other hand, when water temperature was decreased from 21 to 12°C at a rate of 0·5°C h⁻¹, oxygen consumption was correlated with both heart rate and cardiac output but not with blood oxygen extraction. When fish were forced to swim increasingly faster, heart rate, cardiac output and blood oxygen extraction all correlated positively with oxygen consumption. For both cardiac output and heart rate, the slope of the regression line with oxygen consumption was elevated significantly more when the fish were forced to swim at increasingly higher swimming speeds than when water temperature was increased or decreased. The variation of the regression lines between cardiac output and oxygen consumption indicated that cardiac output presents few advantages over heart rate as a predictor of metabolic rate.     

The effect of feedback-assisted reduction in heart rate reactivity on videogame performance

In 67 male volunteers, we examined the reduction of cardiovascular responsivity to a psychomotor challenge (videogame) achieved by use of heart rate (HR) feedback and effects of these procedures on concomitant behavioral performance. Each subject participated in a pretraining assessment of his cardiovascular responses to the videogame, a training condition, and a posttraining assessment identical to the initial evaluation. During training, subjects were assigned to one of four conditions: (a) a habituation control group receiving no instructions to alter HR (HC); (b) an instructions-only control group receiving instructions to maintain a low or unchanged HR during videogame presentations (IC); (c) a feedback group receiving instructions to reduce HR using ongoing HR feedback (FB–); or (d) a feedback group receiving instructions to lower HR and given HR feedback plus a score contingency in which total game score was jointly determined by subjects' game performance and success at HR control (FB+). Subjects receiving feedback (FB+, FB–) exhibited greater reductions in HR response to the videogame in the posttraining assessment than control (HC, IC) subjects; FB+ subjects showed greater HR reductions than subjects in any other group. FB+ and FB– subjects showed a lower SBP at posttraining relative to the two control groups, but no reduction in task-induced blood pressure reactivity. There were no group differences in videogame performance, either before or following training.The authors wish to thank Fred Claus, who served as a research assistant for this study.     

心梗后心肌重构过程中AT1A，AT2受体表达的变化

为探讨AT1,AT2受体在心肌重构演变过程中的作用,本实验应用免疫组化,电镜技术和图像分析方法,观察了大鼠心梗后心肌重构过程中非醒,AT1,AT2受体表达的动态变化,结果显示,心梗术后3d,电镜显示非梗塞区心肌细胞肌原纤维横纹消失,线粒体肿胀,成纤维细胞增多,免疫组化显示AT1A受体在非梗塞区心肌组织表达明显升高（P＜0．001）,AT2受体表达无明显变化（P＞0．05）,心梗术后14天,可见心肌细胞肌原纤维模纹,心肌细胞间胶原纤维明显增多。同时AT1A受本在心肌的表达比心梗术后3天时减弱,但仍高于对照组（P＜0．05）,AT2受体表达明显增加（P＜0．001）,结果提示：心梗后非梗塞区心肌AT1A,AT2受体表达先后上调,可能参与介导心肌重构过程。     

Circadian and short-term regulation of blood pressure and heart rate in transgenic mice with cardiac overexpression of the beta1-adrenoceptor

Congestive heart failure is associated with a loss of circadian and short-term variability in blood pressure and heart rate. In order to assess the contribution of elevated cardiac sympathetic activity to the disturbed cardiovascular regulation, we monitored blood pressure and heart rate in mice with cardiac overexpression of the β₁-adrenoceptor prior to the development of overt heart failure. Telemetry transmitters for continuous monitoring of blood pressure and heart rate were implanted in 8 to 9-week-old wildtype and transgenic mice, derived from crosses of heterozygous transgenic (line β₁TG4) and wildtype mice. Cardiovascular circadian patterns were analyzed under baseline conditions and during treatment with propranolol (500 mg/L in drinking water). Short-term variability was assessed by spectral analysis of beat-to-beat data sampled for 30 min at four circadian times. Transgenic β₁TG4 mice showed an increase in 24 h heart rate, while blood pressure was not different from wildtype controls. Circadian patterns in blood pressure and heart were preserved in β₁TG4 mice. Addition of propranolol to the animals' drinking water led to a reduction in heart rate and its 24 h variation in both strains of mice. Short-term variability in blood pressure was not different between wildtype and β₁TG4 mice, but heart rate variability in the transgenic animals showed a rightward shift of the high-frequency component in the nocturnal activity period, suggesting an increase in respiratory frequency. In conclusion, the present study shows that both the circadian and the short-term regulation of blood pressure and heart rate are largely preserved in young, nonfailing β₁-transgenic mice. This finding suggests that the loss of blood pressure and heart rate variability observed in human congestive heart failure cannot be attributed solely to sympathetic overactivity but reflects the loss of adrenergic responsiveness to changes in the activity of the autonomic nervous system.