ROLE OF VENTROLATERAL MEDULLA IN THE BAROREFLEX

该申请提出调查去甲肾上腺素 猫尾侧延髓腹外侧区（VLM）的含神经元是 由于动脉血压急剧升高而兴奋， 在吻侧VLM中含有神经元的神经元被抑制， 动脉血压 进一步提出尾侧VLM神经元 影响VLM吻侧神经元的活动， 连接或通过间接途径。 因此， 尾侧和喙侧VLM神经元构成VLM中的神经元机制， 猫的交感神经活动的压力反射控制的一部分。 VLM神经元是压力感受器反射的一部分的概念将是 在麻醉猫中进行了研究， 分离的颈动脉窦（其他去神经的压力感受器区域）并制备 用于记录尾侧和吻侧VLM的单个单位活动 神经元 VLM神经元对压力感受器输入的行为将是 通过系统地压迫颈动脉窦并记录 神经元活动对这种压力感受器输入的反应。 完成后 在每次实验中，这些猫的脑干将被处理， 去甲肾上腺素和肾上腺素免疫细胞化学鉴定 含有神经元。 含有去甲肾上腺素的神经元将被鉴定为 那些只被多巴胺-β-羟化酶抗体染色的神经元 （兔）和肾上腺素含有神经元的那些染色与 苯乙醇胺-N-甲基转移酶抗体（兔）。 响应 单个神经元的特性将与它们的位置相关， 在含有去甲肾上腺素和肾上腺素的神经元群体中， 的VLM。 提出了额外的实验来研究可能的 尾侧VLM神经元可通过其影响活动的神经通路 VLM神经元。 第一，尾侧VLM神经元向 同侧吻侧VLM将通过使用逆行 记录场的微刺激和/或尖峰触发平均 潜力 第二，尾侧和吻侧之间的单突触联系 VLM神经元将通过记录以下神经元的同时活动来研究： 这些神经元对和交叉相关分析的应用。 第三，从尾侧VLM到 通过NTS中的神经元研究吻侧VLM神经元， 尾侧腹主动脉膜轴突投射的电生理测定 同侧NTS结合电生理 确定从NTS到同侧吻侧的轴突投射 VLM。 拟议的实验应有助于理解 VLM在压力反射控制循环中的作用。

The application proposes to investigate the hypothesis that noradrenaline containing neurons in the caudal ventrolateral medulla (VLM) of the cat are excited by acute increases in arterial blood pressure and that adrenaline containing neurons in the rostral VLM are inhibited by acute increases in arterial blood pressure. Further it is proposed that caudal VLM neurons influence the activity of rostral VLM neurons either through monosynaptic connections or through indirect pathways. Thus, interactions between caudal and rostral VLM neurons constitute neuronal mechanisms in the VLM of the cat that are part of baroreflex control of sympathetic nerve activity. The concept that VLM neurons are part of the baroreflex will be investigated in anesthetized cats prepared with a single innervated isolated carotid sinus (other baroreceptor regions denervated) and prepared for the recording of single unit activity of caudal and rostral VLM neurons. The behavior of VLM neurons to baroreceptor input will be examined by systematically forcing carotid sinus pressure and recording neuronal activity in response to this baroreceptor input. After completion of each experiment the brain stem of these cats will be processed for immunocytochemical identification of noradrenaline and adrenaline containing neurons. Noradrenaline containing neurons will be identified as those neurons that stain only with dopamine-beta-hydroxylase antibodies (rabbit) and adrenaline containing neurons as those that stain with phenylethanolamine-N-methyltransferase antibodies (rabbit). The response properties of individual neurons will be correlated to their location within populations of noradrenaline and adrenaline containing neurons in the VLM. Additional experiments are proposed to investigate the probable neural pathways through which caudal VLM neurons can influence the activity of rostral VLM neurons. First, the projection of caudal VLM neurons to the ipsilateral rostral VLM will be determined through the use of antidromic microstimulation and/or spike-triggered averaging of recorded field potentials. Second, monosynaptic connections between caudal and rostral VLM neurons will be investigated by recording simultaneous activity from pairs of these neurons and application of cross correlation analysis. Third, the possibility of an indirect pathway from the caudal VLM to rostral VLM neurons via neurons in the NTS will be investigated by electrophysiologic determination of axonal projections from the caudal VLM to the ipsilateral NTS in combination with the electrophysiologic determination of axonal projections from the NTS to the ipsilateral rostral VLM. The proposed experiments should contribute to the understanding of the role of VLM in baroreflex control of the circulation.