CENTRAL INTERACTION OF BARORECEPTOR & SOMATIC AFFERENTS

交感心血管机制被慢性疾病所改变 疾病，如充血性心力衰竭，以及急性 压力，如体力活动或锻炼。的总体目标 这项建议是为了了解 有助于动脉压力感受器的“可塑性” 反射弧线。假设1：收缩引起的激活 骨骼肌受体调节颈动脉压力感受器反射。 机械和代谢敏感的后肢的影响 颈动脉压力感受器反射的骨骼肌传入活动 功能将被调查。颈动脉压力感受器将是 以分离和灌流的颈动脉窦为特征的 麻醉犬体内的制备和骨骼肌受体 将被腹根刺激和被动肌肉激活 伸展一下。实验将定义以下操作特性 颈动脉压力感受器反射，以及识别频率依赖性 利用传递函数对反射特性进行分析。 假设2：孤束核(NTS)是 传入压力感受器和骨骼肌的神经基质 感受器纤维。骨骼肌传入纤维将被追踪 用凝集素标记的辣根过氧化物酶(HRP)标记NTS 应用于猫的胫神经。HRP-的共局化 NTS阳性神经元和Fos阳性神经元被激活 肌肉收缩将被用来确定 免疫组织化学染色技术。假设3： 来自骨骼肌受体的传入输入改变 压力敏感的NTS神经元的兴奋性。胞外单- 在受控期间，将记录NTS神经元的单位活动 激活压力感受性反射和骨骼肌反射 犬类和猫科动物的模型。这些活动的主要焦点是 研究是确定不同的尖峰放电的作用 NTS神经元的模式。拟议的实验将是 在系统和细胞层面上进行。结果 从这些实验中将提供关于 NTS神经元对内脏输入的突触处理。这 知识可能会帮助我们更好地理解中枢机制 改变动脉压力感受性反射对心血管功能的控制 无论是健康还是疾病。

Sympathetic cardiovascular mechanisms are modified by chronic diseases, such as congestive heart failure, as well as by acute stress such as physical activity or exercise. The overall aim of this proposal is to understand the central mechanisms that contribute to the "plasticity" of the arterial baroreceptor reflex arc. Hypothesis number 1: Contraction-induced activation of skeletal muscle receptors modulate the carotid baroreflex. Effect of mechanically and metabolically-sensitive hindlimb skeletal muscle afferent activity on carotid baroreceptor reflex function will be investigated. Carotid baroreceptors will be characterized using the isolated and perfused carotid sinus preparation in anesthetized dogs, and skeletal muscle receptors will be activated by ventral root stimulation and passive muscle stretch. Experiments will define the operational properties of the carotid baroreflex, as well as identify frequency-dependent characteristics of the reflex using transfer function analysis. Hypothesis number 2: Nucleus tractus solitarii (NTS) is the neural substrate for afferent baroreceptor and skeletal muscle receptor fibers. Skeletal muscle afferent fibers will be traced to the NTS using lectin-conjugated horseradish peroxidase (HRP) applied to the tibial nerve in cats. Colocalization of HRP- positive NTS neurons with Fos-positive neurons activated by muscle contraction will be determined utilizing immunohistochemical staining techniques. Hypothesis number 3: Afferent input from skeletal muscle receptors alters the excitability of barosensitive NTS neurons. Extracellular single- unit activity will be recorded from NTS neurons during controlled activation of the baroreflex and the skeletal muscle reflex using both canine and feline models. The primary focus of these studies is to determine the role for differential spike firing patterns in NTS neurons. The proposed experiments will be conducted at both the systems and the cellular levels. Results from these experiments will provide new information regarding the synaptic processing of visceral inputs by NTS neurons. This knowledge may help us to better understand the central mechanisms that alter arterial baroreflex control of cardiovascular function in both health and disease.