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1.
目的观察体位改变对Beagle犬心脏自主神经控制的影响。方法利用大动物无创生理遥测技术,监测清醒活动状态下雌性Beagle犬在静态姿势(lying、standing、sitting、hanging)和运动(walking)姿势下的心电图(ECG),并用HRV功率谱分析其自主神经功能。结果在静态姿势下,Beagle犬RR间期(RRI)、RR间期的标准差SDNN(SDNN)、相邻RR间期差值平方和的均方根RMSSD(RMSSD)、相邻R-R间期差值〉50 ms的窦性个数占心搏总数的百分比pNNabs(50)(pNNabs(50))、TP总功率(TP)、VLF极低频功率(VLF)、标准化高频功率(HFnorm)均明显高于运动状态(P〈0.05,P〈0.01),而心率(HR)、标准化低频功率(LFnorm)和低频功率/高频功率(LF/HF)平衡指数则明显低于运动状态(P〈0.05,P〈0.01)。结论不同体位姿势在静息状态下以迷走神经活动兴奋为主,相反,在运动状态下以交感神经活动兴奋为主;体位姿势改变能引起心率的变化,必然影响心脏自主神经控制能力,其主要取决于迷走神经活动强弱有关,且导致LF/HF均衡性的破坏。  相似文献   

2.
蓝斑对迷走—心血管反射的影响   总被引:1,自引:0,他引:1  
实验用家兔36只,采用低频和高频电流刺激颈部迷走神经中枢端,建立迷走-减压和迷走-升压反射,两种频率电刺激均导致肾交感神经传出活动减少。以迷走-血压反射和迷走-交感反射为指标,连续电流刺激蓝斑或LC微量注射谷氨酸钠均抑制迷走-血压反射和迷走-交感反射。  相似文献   

3.
P物质在脊髓水平对心血管活动的影响   总被引:1,自引:1,他引:0  
为阐明起源于延髓,下行达脊髓侧角的P物质(SP)纤维在心血管活动中的作用,我们在乌拉坦麻醉的大鼠上进行了以下实验:(1)在完整大鼠脊髓蛛网膜下腔注射(ith)SP(15nmol/10μl),观察到内脏交感神经放电、心率及平均动脉血压均有明显升高。(2)在颈_1(C_1)横断脊髓的大鼠,ith 相同剂量相同体积的SP 却引起内脏交感神经放电及平均动脉血压轻度下降,心率稍有增加。(3)C_1 横断脊髓的大鼠静脉注射相同剂量的SP 则引起平均动脉血压急速降低及内脏交感神经放电增加,提示SP 在脊髓水平的直接作用系通过抑制交感传出放电而引起血压降低。(4)用ith PS 的1/10剂量、1/5体积给完整大鼠脑池注射(ici),观察到血压及内脏交感神经放电增加,但心率没有变化。 上述结果表明,(1)SP 作用于脑和脊髓,对心血管功能可能有不同的作用。(2)ith SP对完整大鼠心血管功能的作用是多途径的。  相似文献   

4.
不同年龄健康被试者心率变异性的谱分析研究   总被引:1,自引:0,他引:1  
对不同年龄健康男性被试者卧、立位条件下,心率变异性(heart rate variability,HRV)谱高、低频成分随年龄变化的规律进行研究。结果表明:虽然各年龄组间卧、立位时的静息平均心率并无显著差别,但HRV却随年龄的增长而明显降低,青年组HRV谱高、低频谱峰功率的显著高于中年组、中老年组及老年组(P〈0.05或P〈0.01);HRV谱低频谱功率、高频谱功率及总功率均随年龄增长呈指数衰减规  相似文献   

5.
给乌拉坦麻醉六鼠侧脑室注射P物质(SP)10μg,引起动脉血压、心率和内脏交感神经放电增加。同样剂量的SP静脉注射后却引起血压降低。阿托品预处理不影响SP的开心率作用。预先脑室注射0.25,4,64μg阿片受体拮抗剂纳洛酮,对SP的升压效应有剂量依赖式对抗作用。以上说明脑室注射SP 引起的血压升高是交感神经活动增强,导致心率加快及外周血管紧张性增加的结果,并提示SP的中枢升压效应可能与脑内释放内源性阿片样物质有关。  相似文献   

6.
Li L  Zhu JW  Cao YX  Li P 《生理学报》1998,50(5):519-524
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  相似文献   

7.
中枢5-羟色胺与心血管活动调节   总被引:1,自引:0,他引:1  
中枢神经系统中不同的5-HT通路,在心血管活动调节中可能具有不同的效应。兴奋脑干-下丘脑5-HT的上行通路可升高血压;兴奋脑干-脊髓的5-HT下行通路则降低血压,抑制交感神经活动。二条5-HT通路通过下丘脑和孤束核相互联系,在心血管反射通路的不同环节中起不同作用。  相似文献   

8.
实验在氯醛糖麻醉、去缓冲神经、用三碘季铵酚麻痹和人工呼吸的86只猫身上进行。应用自功率谱(autosperum)和相干分析法(coherence analysis)证实了大脑额-项叶电活动(EEG)和心下交感神经冲动(SND)之间明显相关(34/44例)。SND活动落后于EEG50±20ms,互相关值(cross-correlation value)为0.4±0.1,相干值为0.25±0.05,均有显著的统计学意义。去大脑(A_3平面)使SND(3-4.2Hz频带)的功率明显下降的同时BP下降(5.47±0.13kPa),但EEG的总功率却保持不变,只是它与SND之间不再存在相关关系。在1h内SND节律和BP逐渐恢复。如果事先损伤下丘脑外侧部或中央丘脑,则上述去大脑的现象大大减弱。实验结果表明:猫前脑通过间脑有关的结构下传冲动调节和设置了交感神经活动的水平,一旦这种联系被阻断,脑干有关的心血管中枢就会代偿性维持交感神经活动。  相似文献   

9.
本工作记录家兔的肾交感神经冲动、动脉血压和心率,观察到以低频率、低强度刺激腓深神经(强度3伏,频率12次/秒,波宽0.5毫秒,持续20分钟),可以显著抑制肾交感神经的放电活动,但对血压和心率无显著影响。刺激腓深神经后吸10%氧引起缺氧时的交感兴奋和升压反射以及夹闭一侧颈总动脉引起的升压反射均受到抑制。这些抑制现象可因静脉注射纳洛酮(0.4毫克/公斤)而被翻转。结果表明:低频低强度的腓深神经刺激可抑制交感缩血管中枢及升压反射,这种抑制效应和内源性鸦片样物质的释放有关。  相似文献   

10.
实验用家兔36只,采用低频(5-8Hz)和高频(50-100Hz)电流刺激颈部迷走神经中枢端(VAS),建立迷走-减压和迷走-升压反射,两种频率电刺激均导致肾交感神经传出活动(RSA)减少。以迷走-血压反射和迷走-交感反射为指标,连续电流刺激蓝斑(LC)或LC微量注射谷氨酸钠均抑制迷走-血压反射和迷走-交感反射。而连续电流刺激LC或LC微量注射谷氨酸钠本身均引起平均动脉血压升高和RSA增加。本文对新近提出的对LC整体功能认识的理论,结合本文的结果进行了讨论  相似文献   

11.
The decline in physical capacity in the elderly can be ameliorated by low-velocity, low-impact exercises. Wai tan kung (WTK), a traditional Taiwanese conditioning exercise, is suitable for older people. This study evaluated the effect of WTK on autonomic nervous modulation in the elderly. Twenty WTK practitioners and 20 normal controls were recruited in this study. The stationary state spectral heart rate variability (HRV) measures, hemodynamics, and spirometry between the WTK group and normal controls and sequential changes in HRV measures and hemodynamics after WTK were compared. We found that the standard deviation and coefficient of variation of RR intervals, total power, low frequency power (LFP), and normalized LFP (nLFP) in WTK practitioners before WTK were all significantly higher than those of normal controls. After WTK, the normalized high-frequency power increased (nHFP) significantly from 27.7±13.2 normalized units (nu) before WTK to 37.6±16.0 nu 30 min after WTK, and to 39.8±20.1 nu 60 min after WTK. In contrast, LFP/HFP decreased significantly from 1.3±1.0 before WTK to 1.0±0.9 30 min after WTK and to 0.8±0.6 60 min after WTK. We concluded that in the short term, WTK enhances vagal modulation and suppresses sympathetic modulation, whereas in the long term, WTK enhances sympathetic modulation without compromising vagal modulation of the elderly. Thus WTK is good health-promoting calisthenics that can be recommended to the elderly.  相似文献   

12.
We recorded ambulatory electrocardiograms of 6 long distance truck drivers during their work period in order to observe the affect of autonomic nervous function and symptoms while doing their work. We also recorded their work patterns every minute. The RR50 value and the LFP/HFP ratio were calculated every two minutes based on R-R interval data. RR50 was significantly higher during taking naps than during other periods of work shifts, while, the LFP/HFP ratio showed significantly lower during taking naps than during other periods of work shifts. RR50 in the morning was significantly higher than that in the afternoon. On the contrary, the LFP/HFP ratio showed opposite tendency. Only on the times of driving, RR50 was significantly higher in the morning than that in the afternoon. On the other hand, the LFP/HFP ratio showed an opposite tendency. These results show that the parasympathetic nervous activities were more dominant than sympathetic nervous activities in the morning during the subjects were doing long distance truck driving including midnight work. Driving while in high parasympathetic nervous activity levels may add to cardiovascular stress and lead to drowsiness. And this may result in disrupted attention. It is necessary to decrease work time and improve working conditions of truck drivers working long-hour shifts.  相似文献   

13.
The upper limit of incidence of muscle sympathetic neural bursts can lead to underestimation of sympathetic activity in patients with severe heart failure. This study aimed to evaluate the pulse-synchronous burst power of muscle sympathetic nerve activity (MSNA) as a more specific indicator that could discriminate sympathetic activity in patients with heart failure. In 54 patients with heart failure, the pulse-synchronous burst power at the mean heart rate was quantified by spectral analysis of MSNA. Thirteen patients received a central sympatholytic agent (guanfacine) for 5 days to validate the feasibility of this new index. Both burst incidence and plasma norepinephrine level showed no significant difference between patients in New York Heart Association functional class III (94 +/- 6 per 100 heartbeats and 477 +/- 219 pg/ml, respectively) and class II (79 +/- 14 per 100 heartbeats and 424 +/- 268 pg/ml, respectively). In contrast, the burst power was useful for discriminating patients in class III from those in class II (61 +/- 8% vs. 39 +/- 10%; P < 0.05). Inhibition of sympathetic nerve activity by guanfacine was more sensitively reflected by the change of burst power (-36 +/- 25%) than by that of burst incidence (-12 +/- 14%; P < 0.001). The sympathetic burst power reflects both burst frequency and amplitude independently of the absolute values and provides a sensitive new index for interindividual comparisons of sympathetic activity in patients with heart failure.  相似文献   

14.
In urethan-anesthetized cats, frequency domain analysis was used to explore the mechanisms of differential responses of inferior cardiac (CN), vertebral (VN), and renal (RN) sympathetic nerves to electrical stimulation of a discrete region of the medullary raphe (0-2 mm caudal to the obex). Raphe stimulation in baroreceptor-denervated cats at frequencies (7-12 Hz) that entrained the 10-Hz rhythm in nerve activity decreased CN and RN activities but increased VN activity. The reductions in CN and RN discharges were associated with decreased low-frequency (相似文献   

15.
Nakamura T  Horio H  Miyashita S  Chiba Y  Sato S 《Bio Systems》2005,79(1-3):117-124
Heartbeat intervals, which are determined basically by regular excitations of the sinoatrial node, show significant fluctuation referred to as the heart rate variability (HRV). The HRV is mostly due to nerve activities through the sympathetic and parasympathetic branches of the autonomic nervous system (ANS). In recent years, it has been recognized that the HRV shows a greater complexity than ever expected, suggesting that it includes much information about ANS activities. In this study, we investigated relationship between HRV and development in preterm infants. To this end, heartbeat intervals were continuously recorded from 11 preterm infants in NICU. The recording periods were ranging from several days to weeks depending on the individuals. The HRV at various ages was then characterized by several indices. They include power spectrum as well as the mean and standard deviation of the series. For the power spectrum, the low-frequency band power (LF), high-frequency band power (HF), LF/HF (the ratio between LF and HF), beta (scaling exponent of the spectrum) were estimated. The detrended fluctuation analysis (DFA) was also employed to obtain short- and long-range scaling exponents. Each of these indices showed a correlation with the age. We showed that the long-range scaling exponent, derived from the DFA, was most significantly correlated with the age, suggesting that it could be a robust index to characterize the development of preterm infants.  相似文献   

16.
Aim was to elucidate autonomic responses to dynamic and static (isometric) exercise of the lower limbs eliciting the same moderate heart rate (HR) response. Method: 23 males performed two kinds of voluntary exercise in a supine position at similar heart rates: static exercise (SE) of the lower limbs (static leg press) and dynamic exercise (DE) of the lower limbs (cycling). Subjective effort, systolic (SBP) and diastolic blood pressure (DBP), mean arterial pressure (MAP), rate pressure product (RPP) and the time between consecutive heart beats (RR-intervals) were measured. Time-domain (SDNN, RMSSD), frequency-domain (power in the low and high frequency band (LFP, HFP)) and geometric measures (SD1, SD2) as well as non-linear measures of regularity (approximate entropy (ApEn), sample entropy (SampEn) and correlation dimension D2) were calculated. Results: Although HR was similar during both exercise conditions (88±10 bpm), subjective effort, SBP, DBP, MAP and RPP were significantly enhanced during SE. HRV indicators representing overall variability (SDNN, SD 2) and vagal modulated variability (RMSSD, HFP, SD 1) were increased. LFP, thought to be modulated by both autonomic branches, tended to be higher during SE. ApEn and SampEn were decreased whereas D2 was enhanced during SE. It can be concluded that autonomic control processes during SE and DE were qualitatively different despite similar heart rate levels. The differences were reflected by blood pressure and HRV indices. HRV-measures indicated a stronger vagal cardiac activity during SE, while blood pressure response indicated a stronger sympathetic efferent activity to the vessels. The elevated vagal cardiac activity during SE might be a response mechanism, compensating a possible co-activation of sympathetic cardiac efferents, as HR and LF/HF was similar and LFP tended to be higher. However, this conclusion must be drawn cautiously as there is no HRV-marker reflecting “pure” sympathetic cardiac activity.  相似文献   

17.
Although regional difference in sympathetic efferent nerve activity has been well investigated, whether this regional difference exists in the dynamic baroreflex regulation of sympathetic nerve activity remains uncertain. In anesthetized, vagotomized, and aortic-denervated rabbits, we isolated carotid sinuses and randomly perturbed intracarotid sinus pressure (CSP) while simultaneously recording cardiac (CSNA) and renal sympathetic nerve activities (RSNA). The neural arc transfer function from CSP to CSNA and that from CSP to RSNA revealed high-pass characteristics. The increasing slope of the transfer gain in the frequencies between 0.03 and 0.3 Hz was significantly greater for CSNA than for RSNA (2.96 +/- 0.72 vs. 1.64 +/- 0.73 dB/octave, P < 0.01, n = 9). The difference was hardly explained by the difference in static nonlinear characteristics of CSP-CSNA and CSP-RSNA relationships or by the difference in conduction velocities in the multifiber recording. These results indicate that the central processing in the brain stem differs between CSNA and RSNA. The neural arc of the baroreflex may exert differential effects on the heart and kidney in response to dynamic baroreflex activation.  相似文献   

18.
The close apposition between sympathetic and parasympathetic nerve terminals in the adventitia of cerebral arteries provides morphological evidence that sympathetic nerve activation causes parasympathetic nitrergic vasodilation via a sympathetic-parasympathetic interaction mechanism. The decreased parasympathetic nerve terminals in basilar arteries (BA) of spontaneously hypertensive rat (SHR) and renovascular hypertensive rats (RHR) compared with Wistar-Kyoto rats (WKY), therefore, would diminish this axo-axonal interaction-mediated neurogenic vasodilation in hypertension. Increased basilar arterial blood flow (BABF) via axo-axonal interaction during sympathetic activation was, therefore, examined in anesthetized rats by laser-Doppler flowmetry. Electrical stimulation (ES) of sympathetic nerves originating in superior cervical ganglion (SCG) and topical nicotine (10-30 μM) onto BA of WKY significantly increased BABF. Both increases were inhibited by tetrodotoxin, 7-nitroindazole (neuronal nitric oxide synthase inhibitor), and ICI-118,551 (β(2)-adrenoceptor antagonist), but not by atenolol (β(1)-adrenoceptor antagonist). Topical norepinephrine onto BA also increased BABF, which was abolished by atenolol combined with 7-nitroindazole or ICI-118,551. Similar results were found in prehypertensive SHR. However, in adult SHR and RHR, ES of sympathetic nerves or topical nicotine caused minimum or no increase of BABF. It is concluded that excitation of sympathetic nerves to BA in WKY causes parasympathetic nitrergic vasodilation with increased BABF. This finding indicates an endowed functional neurogenic mechanism for increasing the BABF or brain stem blood flow in coping with increased local sympathetic activities in acutely stressful situations such as the "fight-or-flight response." This increased blood flow in defensive mechanism diminishes in genetic and nongenetic hypertensive rats due most likely to decreased parasympathetic nitrergic nerve terminals.  相似文献   

19.
The ratio between low-frequency (LF) and high-frequency (HF) spectral power of heart rate has been used as an approximate index for determining the autonomic nervous system (ANS) balance. An accurate assessment of the ANS balance can only be achieved if clear separation of the dynamics of the sympathetic and parasympathetic nervous activities can be obtained, which is a daunting task because they are nonlinear and have overlapping dynamics. In this study, a promising nonlinear method, termed the principal dynamic mode (PDM) method, is used to separate dynamic components of the sympathetic and parasympathetic nervous activities on the basis of ECG signal, and the results are compared with the power spectral approach to assessing the ANS balance. The PDM analysis based on the 28 subjects consistently resulted in a clear separation of the two nervous systems, which have similar frequency characteristics for parasympathetic and sympathetic activities as those reported in the literature. With the application of atropine, in 13 of 15 supine subjects there was an increase in the sympathetic-to-parasympathetic ratio (SPR) due to a greater decrease of parasympathetic than sympathetic activity (P=0.003), and all 13 subjects in the upright position had a decrease in SPR due to a greater decrease of sympathetic than parasympathetic activity (P<0.001) with the application of propranolol. The LF-to-HF ratio calculated by the power spectral density is less accurate than the PDM because it is not able to separate the dynamics of the parasympathetic and sympathetic nervous systems. The culprit is equivalent decreases in both the sympathetic and parasympathetic activities irrespective of the pharmacological blockades. These findings suggest that the PDM shows promise as a noninvasive and quantitative marker of ANS imbalance, which has been shown to be a factor in many cardiac and stress-related diseases.  相似文献   

20.
The floor plate is a signaling center in the ventral neural tube of vertebrates with important functions during neural patterning and axon guidance. It is composed of a centrally located medial floor plate (MFP) and a bilaterally positioned lateral floor plate (LFP). While the role of the MFP as source of signaling molecules like, e.g., Sonic Hedgehog (Shh) is well understood, the exact organization and function of the LFP are currently unclear. Based on expression analyses, the one cell wide LFP in zebrafish has been postulated to be a homogenous structure. We instead show that the zebrafish trunk LFP is discontinuously arranged. Single LFP cells alternate with p3 neuronal precursor cells, which develop V3 interneurons along the anteroposterior (AP) axis. Our mutant analyses indicate that both, formation of LFP and p3 cells require Delta-Notch signaling. Importantly, however, the two cell types are differentially regulated by Hedgehog (HH) and Nkx2.2 activities. This implicates a novel mechanism of neural tube patterning, in which distinct cell populations within one domain of the ventral neural tube are differently specified along the AP axis. We conclude that different levels of HH and Nkx2.2 activities are responsible for the alternating appearance of LFP and p3 neuronal progenitor cells in the zebrafish ventral neural tube.  相似文献   

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