POSTNATAL MATURATION OF CARDIOVASCULAR REGULATORY SYSTEM

描述：(改编自《调查者摘要》) 相干性(即神经信号中的相关周期)已知 以与年龄相关的方式出现，并被视为神经疾病的证据 振荡器。交感神经放电(SND)的一致性 发育中的猪将使用神经生理学和 神经解剖学技术。调查人员将确定其有效性 下列与发展连贯有关的假设 SND：具体地说：1)SND的连贯性将显示与年龄相关的头颅- 具有节前滞后的尾部倾斜，2)一致性是一种 脑干紧急网络的联系功能，3)压力感受器和 吸气网络输入参与了连贯的出现 周期性，以及4)脑干CV调节系统的主要部位 可通过使用横断神经轴定位，并野 以及单个神经元的记录。中的正确顺序的知识 SND周期的发展和一致性的开始可能是 如果没有发生这种协调活动，则具有临床意义 并防止新生儿在一个完整的 与年龄相关的模式。这些假设将在萨凡接受检验。 麻醉仔猪(1天以下-3个月龄)。排泄物 至少两条交感神经(内脏、颈交感、 腓、腰、肾)将与膈同时记录 活动(呼吸模式发生器的监视器)，并将包括 迷走神经和颈动脉窦神经的失神经及特殊横断 包括脊髓在内的神经轴。简历的标识 监管制度将涉及以下进展：a) 表达Fos to的脑干部位的确定 压力感受器/化学感受器操作，b)CV(心率，主动脉 压力、区域动脉血流量)和SND对化学物质的反应 刺激c-fos识别的位点，c)表型表达 在这些功能识别区域内的神经元。音乐中的节奏 SND(1-2赫兹[呼吸调节]，3-6赫兹(通常为心脏调节)) 以8~13赫兹(10赫兹节律)作为识别标志 包括交感脑干回路的神经元(通过相互关联 SND的群体记录和单个神经元活动，包括 功率谱和相干谱分割的数学方法 以识别连接模式)。与年龄相关的变化将是 通过对不同年龄的结果进行统计分析而确定的 组。这些研究的结果应该确定发展 交感神经周期的变化作为出生后成熟的标志 并支持关于以下方面的假设 SND的一致性开始作为出生后的一个主要标志的重要性 成熟。上述实验应该有助于在 交感节律性的各种解释和帮助 将儿童生命中最脆弱的时期理解为 并在小岛屿发展中国家的病因学中确定了可能的机制。

DESCRIPTION: (Adapted from the Investigator's Abstract) Expression of coherence (i.e. correlated periodicities in neural signals) is known to appear in an age-related manner, and is taken as evidence of a neural oscillator. Coherence of sympathetic nerve discharge (SND) in developing swine will be explored using neurophysiologic and neuroanatomic techniques. The investigators will determine the validity of the following Hypotheses concerned with development of coherence of SND: specifically: 1) coherence of SND will show an age-related cephalo- caudal gradient with a pre-postganglionic lag, 2) coherence is a function of linkages of brainstem emergent networks, 3) baroreceptor and inspiratory network inputs are involved in the appearance of coherent periodicities, and 4) major sites of the brainstem CV regulatory system can be located through the use of transection of the neuraxis, and field and single neuron recordings. Knowledge of the proper sequence in the development of SND periodicities and the onset of coherence may be of clinical importance if lack of such coordinated activity fails to occur and prevents the neonate from responding to stresses in an integrated age-related pattern. These hypotheses will be tested in Saffan anesthetized piglets (less than 1 day - 3 months of age). The discharge of at least two sympathetic nerves (splanchnic, cervical sympathetic, peroneal, lumbar, renal) will be recorded simultaneously with phrenic activity (monitor of the respiratory pattern generator) and will include denervation of vagi and carotid sinus nerves and specific transections of the neuraxis including the spinal cord. Identification of the CV regulatory system will involve the following progression: a) determination of brainstem sites expressing Fos to baroreceptor/chemoreceptor manipulations, b) CV (heart rate, aortic pressure, regional arterial blood flows) and SND responses to chemical stimulation of the c-fos identified sites, c) phenotypic expression of neurons within these functionally identified regions. The rhythms in SND (1-2 Hz [respiratory modulated], 3-6 Hz (usually cardiac modulated) and 8-13 Hz ("10 Hz rhythm") will be used as markers for identification of neurons comprising- sympathetic brainstem circuits (by correlating population recording and single neuron activity to SND including the mathematical technique of partialization of power and coherence spectra to identify patterns of connectivity). Age- related changes will be identified by statistical analyses of results from the different age groups. The results of these studies should establish developmental changes in sympathetic periodicities as markers of postnatal maturity of the regulatory system and support the hypotheses concerning the importance of onset of coherence in SND as a major sign of postnatal maturation. The aforementioned experiments should help chose among the various explanations of sympathetic rhythmicity and help in the understanding of the most vulnerable period in the life of the child as well as define a possible mechanism in the etiology of SIDS.