头端延髓腹外侧区血管加压素在刺激中脑dPAG区诱发防御性升压反应中的…

雄性Ｓｐｒａｇｕｅ－Ｄａｗｌｅｙ大鼠,用乌拉坦（７００ｍｇ／ｋｇ）和氯醛糖（３０ｍｇ／ｋｇ）腹腔麻醉。在双侧头端延髓腹外侧区（ｒＶＬＭ区）每侧微量注射血管加压素（ＡＶＰ）（１０ｐｍｏｌ／０．１μｌ）可引起平均动脉压（ＭＢＰ）升高,心率（ＨＲ）变化不明显,每侧微量注射ＡＶＰ的Ｖ１受体拮抗剂ｄ（ＣＨ２）５［Ｔｙｒ（Ｍｅ）＾２］ＡＶＰ（０．１ｎｍｏｌ／０．１μｌ）后ＭＢＰ和ＨＲ无明显变化。若预先在ｒＶＬ     

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     

L－NNA及NO供体对延髓腹外侧头端区神经元自发放电的影响

在麻醉大鼠观察了静注ＮＯ合成酶抑制剂Ｎ－硝基左旋精氨酸（Ｌ－ＮＮＡ）和ＮＯ供体──硝普钠（ＳＮＰ）和ＳＩＮ－Ｉ对血压、心率和延髓腹外侧头端区（ＲＶＬＭ）神经元自发放电活动的影响,旨在探讨Ｌ－ａｒｇ：ＮＯ通路对动脉血压调节的中枢作用部位。所得结果如下：（１）静注Ｌ－ＮＮＡ后,平均动脉压（ＭＡＰ）升高,心率（ＨＲ）加快,１１个ＲＶＬＭ神经元自发放电频率增加。这些变化发生于给药后５ｍｉｎ,持续时间达３０ｍｉｎ以上。（２）静注ＳＮＰ后,ＭＡＰ降低,ＨＲ加快,２３个ＲＶＬＭ神经元自发放电频率降低,且有剂量依赖性。ＳＮＰ作用发生快,持续时间短。为了排除脑缺血的影响,还特意向一侧颈动脉内注射相同剂量ＳＮＰ,结果引起ＭＡＰ轻度降低,而ＨＲ无明显改变,但ＲＶＬＭ神经元自发放电频率仍显著降低。（３）静注另一ＮＯ供体ＳＩＮ－Ｉ后,ＭＡＰ降低,１１个ＲＶＬＭ神经元自发放电频率降低．与ＳＮＰ的效应基本一致。以上结果提示,ＲＶＬＭ是Ｌ－ａｒｇ：ＮＯ通路实现动脉血压调节的一个中枢作用部位。     

延髓头端腹外侧区血管升压素能机制在应激性高血粘度中的作用

观察延髓头端腹外侧区（ｒＶＬＭ）微量注射血管升压素（ＡＶＰ）能否影响正常大鼠的血压和血粘度,并分析ｒＶＬＭ内ＡＶＰ能机制在清醒大鼠经悬吊加束缚引起应激性升压反应和高血粘度中的影响。结果如下：⑴正常大鼠双侧ｒＶＬＭ微量注射ＡＶＰ（每侧０．５μｇ／０．５μｌ）,可引起血压和血粘度升高;此作用可被事先在同一位置微量注射ＡＶＰ－Ｖ１受体拮抗剂ｄ（ＣＨ２）５「Ｔｙｒ（Ｍｅ）＾２」ＡＶＰ（每侧０．１μｇ／０．     

兔头端腹外侧延髓和蓝斑联系的电生理学研究

在１８只轻度麻醉、去小脑、肌松、人工通气的家兔身上,采用微电极记录技术观察蓝斑（ＬＣ）单位活动和头端腹外侧延髓（ＲＶＬＭ）向ＬＣ投射的一些电生理学特征。记录到１０８个ＬＣ单位,其中９３个单位表现低频、规则的放电活动,放电频率为５．１Ｈｚ,另１５个单位为钳夹皮肤诱发放电的静止单位;这１０８个单位中,６４（５９．２％）个单位对触毛刺激、９３（８６．１％）个单位对钳夹皮肤产生兴奋性反应;电刺激ＲＶＬＭ,     

延髓头端腹外侧区注入肾上腺素对血液流变学的影响

实验用ＳＤ雄性大鼠７８只,采用束缚方法引起应激性高血粘度和血压升高。结果：（１）清醒大鼠束缚２ｄ可引起应激性高血粘度和血压升高。（２）双侧延髓头端腹外侧区（ｒＶＬＭ）微量注射肾上腺素（Ｅ,每侧０．５μｇ／０．５μｌ）可引起血粘度明显增高,此作用可预先在双侧ｒＶＬＭ注入α肾上腺素能受体阻断剂酚妥拉明所阻断,不能被β－肾上腺能受体阻断剂心得安所阻断。用同样剂量Ｅ注入双侧延髓尾端腹外侧区（ｃＶＬＭ）或静     

乙酰胆碱对大鼠头端延髓腹外侧区前交感神经元放电的作用

实验采用细胞外记录和微电泳等电生理方法,研究乙酰胆碱（ＡＣｈ）对氨基甲酸乙酯麻醉的大鼠头端延髓腹外侧区（ＲＶＬＭ）前交感神经元放电频率的影响。在ＲＶＬＭ共记录到３５个前交感神经元,微电泳ＡＣｈ能增加其放电（Ｐ〈０．０５）,并且具有剂量依赖性。其中２２个神经元微电泳Ｍ型胆碱受体阻断剂阿托品（ＡＴＲ）后能明显降低前交感神经元的基础放电（Ｐ〈０．０５）和完全阻断ＡＣｈ引起的神经元兴奋作用;分别向其余７和     

延髓腹外侧区微量注射L－NNA和SNP对大鼠血压、心率和肾交感神经活动的影响

在麻醉大鼠观察了向延髓腹外侧区微量注射ＮＯ合成酶抑制剂Ｎ－硝基左旋精氨酸（ＬＮＮＡ）和硝普钢（ＳＮＰ）对血压、心率和肾交感神经活动的影响,旨在探讨中枢左旋精氨酸－ＮＯ通路在动脉血压调节中的作用及其机制。实验结果如下：（１）向延髓腹外侧头端区（ＲＶＬＭ）注射Ｌ－ＮＮＡ后,平均动脉压（ＭＡＰ）升高,肾交感神经活动（ＲＳＮＡ）增强;心率（ＨＲ）减慢,但无统计学意义。ＭＡＰ和ＲＳＮＡ的变化持续３０ｍｉｎ以上;此效应可被预先静注左旋精氨酸所逆转。（２）向ＲＶＬＭ微量注射ＳＮＰ,ＭＡＰ降低,ＲＳＮＡ减弱;但ＨＲ的变化无统计学意义。（３）向延髓腹外侧尾端区（ＣＶＬＭ）注射Ｌ－ＮＮＡ,ＭＡＰ降低,ＨＲ减慢,ＲＳＮＡ减弱。（４）向ＣＶＬＭ微量注射ＳＮＰ,ＭＡＰ升高,ＲＳＮＡ增强,而心率无明显变化。以上结果表明,中枢左旋精氨酸－ＮＯ通路对延髓腹外侧部的神经元活动有调变作用。     

不同年龄健康被试者心率变异性的谱分析研究

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     

延髓头端腹外侧区神经元电活动与心血管活动相干性的研究

本文分析了大鼠延头端腹外侧区（ＲＶＬＭ）神经元单位活动与心血管活动的相干性,观察了ＲＶＬＭ区神经元电 对电刺激中脑防御反应区的诱发反应,以及对压力感受性反射的反应,并用ＦＦＴ对ＲＶＬＭ区神经元自发单位放电和血压波进行频域的相干性分析,以判断是具有心节律。还分析了ＲＶＬＭ区单位放电变异性与心率变异性的相干性。结果显示：ＲＶＬＭ区大多数神经元对电刺激中脑防御反应区呈兴奋反应（６７％）,７０％神经元放电     

Influence of Cheyne-Stokes respiration on ventricular response to atrial fibrillation in heart failure.

In subjects with sinus rhythm, respiration has a profound effect on heart rate variability (HRV) at high frequencies (HF). Because this HF respiratory arrhythmia is lost in atrial fibrillation (AF), it has been assumed that respiration does not influence the ventricular response. However, previous investigations have not considered the possibility that respiration might influence HRV at lower frequencies. We hypothesized that Cheyne-Stokes respiration with central sleep apnea (CSR-CSA) would entrain HRV at very low frequency (VLF) in AF by modulating atrioventricular (AV) nodal refractory period and concealed conduction. Power spectral analysis of R-wave-to-R-wave (R-R) intervals and respiration during sleep were performed in 13 subjects with AF and CSR-CSA. As anticipated, no modulation of HRV was detected at HF during regular breathing. In contrast, VLF HRV was entrained by CSR-CSA [coherence between respiration and HRV of 0.69 (SD 0.22) at VLF during CSR-CSA vs. 0.20 (SD 0.19) at HF during regular breathing, P < 0.001]. Comparison of R-R intervals during CSR-CSA demonstrated a shorter AV node refractory period during hyperpnea than apnea [minimum R-R of 684 (SD 126) vs. 735 ms (SD 147), P < 0.001] and a lesser degree of concealed conduction [scatter of 178 (SD 56) vs. 246 ms (SD 72), P = 0.001]. We conclude that CSR-CSA entrains the ventricular response to AF, even in the absence of HF respiratory arrhythmia, by inducing rhythmic oscillations in AV node refractoriness and the degree of concealed conduction that may be a function of autonomic modulation of the AV node.     

Characterization by stimulation of medullary mechanisms underlying gasping neurogenesis

Our purpose was to evaluate the hypothesis that neurons in the lateral tegmental field of the medulla comprise a pattern generator for neurogenesis of gasping. Stimulations in this area produced changes characteristic of pattern generators in other systems. These included shifts in gasping rhythm and refractory periods for eliciting gasps; the latter varied inversely with spontaneous gasping frequency. These responses were recorded from activities of phrenic and hypoglossal nerves of decerebrate, cerebellectomized, vagotomized, paralyzed, and ventilated cats. Gasping followed freezing the brain stem between pons and medulla. In addition to lateral tegmental loci, gasps were elicited by stimulating areas extending lateral to the nucleus ambiguus and medial to the contralateral medulla. These areas are envisaged to contain axons to or from the pattern generator of lateral tegmental field. Finally, stimulations in sites approximating nucleus tractus solitarius and nucleus ambiguus delayed spontaneous gasps and terminated ongoing gasps. Current required to terminate gasps fell during neural inspiration. Our data are consistent with the lateral tegmental field of medulla comprising a central pattern generator for gasping and pacemaker elements being a component of this pattern generator.     

Medullary lateral tegmental field: control of respiratory rate and vagal lung inflation afferent influences on sympathetic nerve discharge

We used spectral analysis and event-triggered averaging to determine the effects of chemical inactivation of the medullary lateral tegmental field (LTF) on 1) the relationship of intratracheal pressure (ITP, an index of vagal lung inflation afferent activity) to sympathetic nerve discharge (SND) and phrenic nerve activity (PNA) and 2) central respiratory rate in paralyzed, artificially ventilated dial-urethane-anesthetized cats. ITP-SND coherence value at the frequency of artificial ventilation was significantly (P<0.05; n=18) reduced from 0.73+/-0.04 (mean+/-SE) to 0.24+/-0.04 after bilateral microinjection of muscimol into the LTF. Central respiratory rate was unexpectedly increased in 12 of these experiments (0.28+/-0.03 vs. 0.95+/-0.25 Hz). The ITP-PNA coherence value was variably affected by chemical inactivation of the LTF. It was unchanged when central respiratory rate was also not altered, decreased when respiratory rate was increased above the rate of artificial ventilation, and increased when respiratory rate was raised from a value below the rate of artificial ventilation to the same frequency as the ventilator. Chemical inactivation of the LTF increased central respiratory rate in four of six vagotomized cats but did not significantly affect the PNA-SND coherence value. These data demonstrate that the LTF 1) plays a critical role in mediating the effects of vagal lung inflation afferents on SND but not PNA, 2) helps maintain central respiratory rate in the physiological range, but 3) is not involved in the coupling of central respiratory and sympathetic circuits.     

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     

Control of echolocation pulses by neurons of the nucleus ambiguus in the rufous horseshoe bat,Rhinolophus rouxi

Horseradish peroxidase was applied by inotophoretic injections to physiologically identified regions of the laryngeal motor nucleus, the nucleus ambiguus in the CF/FM bat Rhinolophus rouxi. The connections of the nucleus ambiguus were analysed with regards to their possible functional significance in the vocal control system, in the respiration control system, and in mediating information from the central auditory system. The nucleus ambiguus is reciprocally interconnected with nuclei involved in the generation of the vocal motor pattern, i.e., the homonomous contralateral nucleus and the area of the lateral reticular formation. Similarly, reciprocal connections are found with the nuclei controlling the rhythm of respiration, i.e., medial parts of the medulla oblongata and the parabrachial nuclei. Afferents to the nucleus ambiguus derive from nuclei of the 'descending vocalization system' (periaqueductal gray and cuneiform nuclei) and from motor control centers (red nucleus and frontal cortex). Afferents to the nucleus ambiguus, possibly mediating auditory influence to the motor control of vocalization, come from the superior colliculus and from the pontine nuclei. The efferents from the pontine nuclei are restricted to rostral parts of the nucleus ambiguus, which hosts the motoneurons of the cricothyroid muscle controlling the call frequency.     

Effects on respiratory pattern of focal cooling in the medulla of the dog

Studies in cats have shown that, in addition to respiratory neuron groups in the dorsomedial (DRG) and ventrolateral (VRG) medulla, neural structures in the most ventral medullary regions are important for the maintenance of respiratory rhythm. The purpose of this study was to determine whether a similar superficially located ventral region was present in the dog and to assess the role of each of the other regions in the canine medulla important in the control of breathing, in 20 anesthetized, vagotomized, and artificially ventilated dogs, a cryoprobe was used to cool selected regions of the medulla to 15-20 degrees C. Respiratory output was determined from phrenic nerve or diaphragm electrical activity. Cooling in or near the nucleus of the solitary tract altered timing and produced little change in the amplitude or rate of rise of inspiratory activity; lengthening of inspiratory time was the most common timing effect observed. Cooling in ventrolateral regions affected the amplitude and rate of rise of respiratory activity. Depression of neural tidal volume and apnea could be produced by unilateral cooling in two ventrolateral regions: 1) near the nucleus ambiguus and nucleus para-ambiguus and 2) just beneath the ventral medullary surface. These findings indicate that in the dog dorsomedial neural structures influence respiratory timing, whereas more ventral structures are important to respiratory drive.     

安定降低家兔血压和减少刺激下丘脑诱发室性期前收缩的机制分析

家兔62只,用乌拉坦(700mg/kg)和氯醛醣(35mg/kg)静脉麻醉,三碘季铵酚制动,在人工呼吸下进行实验。用电刺激下丘脑近中线区的方法诱发室性期前收缩(HVE)。静脉注射安定(0.5mg/kg)可降低基础血压(BP),减弱刺激下丘脑引起升压反应(指收缩压峰值SBP_(max))和减少HVE。在双侧延髓腹外侧头端区(rVLM)微量注射氟安定(200μg溶于0.5μl中),γ-氨基丁酸(GABA)(6μg溶于0.5μl中)均能降低BP、SBP_(max)和减少HVE,若微量注射印防己毒素(7.5μg溶于0.5μl中)则可使BP上升并增多HVE。而于双侧延髓腹外侧尾端区(cVLM)微量注射同样剂量氟安定、GABA则无上述反应。安定降低BP、SBP_(max)和减少HVE的作用可被双侧rVLM区微量注射GABA受体拮抗剂荷包牡丹碱(3μg溶于0.5μl中)或印防己毒素所消除,但在双侧rVLM区微量注射甘氨酸受体拮抗剂士的宁(1μg溶于0.5μl中)、阿片受体拮抗剂纳洛酮(0.5μg溶于0.5μl中)、胆碱能阻断药阿托品(0.25μg溶于0.5μl中)、东莨菪碱(1.5μg溶于0.5μl中)后仍然存在。 上述结果提示,在双侧rVLM应用GABA受体拮抗剂可消除安定降低BP、SBP_(max)和减少HVE的作用,安定降低BP、SBP_(max)和减少HVE的作用可能通过GABA这一中间环节,而胆碱能受体、阿片受体、甘氨酸受体可能不起重要作用。     

Effects of negative air ions on activity of neural substrates involved in autonomic regulation in rats

The neural mechanism by which negative air ions (NAI) mediate the regulation of autonomic nervous system activity is still unknown. We examined the effects of NAI on physiological responses, such as blood pressure (BP), heart rate (HR), and heart rate variability (HRV) as well as neuronal activity, in the paraventricular nucleus of the hypothalamus (PVN), locus coeruleus (LC), nucleus ambiguus (NA), and nucleus of the solitary tract (NTS) with c-Fos immunohistochemistry in anesthetized, spontaneously breathing rats. In addition, we performed cervical vagotomy to reveal the afferent pathway involved in mediating the effects of NAI on autonomic regulation. NAI significantly decreased BP and HR, and increased HF power of the HRV spectrum. Significant decreases in c-Fos positive nuclei in the PVN and LC, and enhancement of c-Fos expression in the NA and NTS were induced by NAI. After vagotomy, these physiological and neuronal responses to NAI were not observed. These findings suggest that NAI can modulate autonomic regulation through inhibition of neuronal activity in PVN and LC as well as activation of NA neurons, and that these effects of NAI might be mediated via the vagus nerves.     

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。