CNS PROCESSING OF BRONCHOPULMONARY FIBER AFFERENT INPUT

肺和呼吸道中的支气管肺C纤维受体 感觉信息传递到中枢神经系统来调节呼吸模式。这个 受体受肺泡刺激素刺激，如缓激肽和 前列腺素；外源性化学物质，如苯二胍(一种血清素 结构类似物)和辣椒素；由臭氧等环境毒物 和香烟烟雾，以及在严重肺水肿期间。当受到刺激时 支气管肺C纤维受体产生快速浅呼吸 (在此之前可能有呼吸暂停)、心动过缓、低血压和 呼吸道阻力增加。这项研究的长期目标是 描述激活支气管肺C的中枢回路 纤维感受器反射地产生一种快速浅呼吸模式。我们 已确定近端突触(S)在反射通路中处于离散状态 孤束核区(NTS)(6)。我们还收集了 关于远端突触的初步数据表明，传入 来自支气管肺C纤维受体的信息最终调节 腹侧呼吸组(VRG)神经元的活动。我们假设 产生快速浅呼吸，支气管肺C纤维传入 输入汇聚到连合NTS离散区域的神经元上，并 然后发散以兴奋吻侧VRG中的神经元，这些神经元在早期放电 以递减模式呼气(早期E或EDEC细胞)。这些 早期(EDEC)细胞，进而抑制球脊髓吸气(I)细胞(TO 减少膈神经活动的幅度和持续时间)，以及 抑制尾侧VRG中呼气末(Late E)放电的E细胞 细胞)和支配脊髓内呼气运动神经元(TO 减少呼气时间)。 研究将在乌拉坦麻醉的大鼠身上进行，我们在其中记录 中枢神经系统的细胞外单位活动，膈神经活动， 潮气量和体动脉压。支气管肺C纤维 向右心房注射PDG将刺激受体。这个 目标是：1)使用细胞外记录来确定，如果神经元 NTS区(先前描述；6)从 2)测定大鼠肺C纤维受体的作用。 刺激支气管肺C纤维受体对大鼠肺组织放电模式的影响 吻侧VRG和Botzinger复合体内的早期E细胞(EDEC) 整个视网膜节和尾侧视网膜节中的晚期E细胞； 利用逆行激活，这些细胞的投射，即到 膈运动核、胸髓、迷走神经或上 喉神经(SLN)；3)用互相关分析确定，

Bronchopulmonary C fiber receptors in the lungs and airways transmit sensory information to the CNS to modulate respiratory pattern. The receptors are stimulated by lung autacoids such as bradykinin and prostaglandins; by exogenous chemicals such as phenyldiguanide (a serotonin structural analog) and capsaicin; by environmental toxicants such as ozone and cigarette smoke, and during severe pulmonary edema. When stimulated the bronchopulmonary C fiber receptors produce rapid shallow breathing (that may be preceded by an apnea), bradycardia, hypotension, and an increase in airway resistance. The long-term goal of this research is to characterize the central circuitry whereby activation of bronchopulmonary C fiber receptors reflexly produces a rapid shallow pattern of breathing. We have identified proximal synapse(s) in the reflex pathway in a discrete region in the nucleus tractus solitarius (NTS) (6). We have also collected preliminary data regarding distal synapses, which suggest that afferent input from the bronchopulmonary C fiber receptors ultimately modulates the activity of neurons in the ventral respiratory group (VRG). We hypothesize that to produce rapid shallow breathing, bronchopulmonary C fiber afferent input converges onto neurons in a discrete region in commissural NTS and then diverges to excite neurons in the rostral VRG that discharge in early expiration with a decrementing pattern (early E or EDEC cells). These early (EDEC) cells, in turn inhibit bulbospinal inspiratory (I) cells (to decrease the amplitude and burst duration of phrenic nerve activity), and inhibit E cells in the caudal VRG that discharge in late expiration (late E cells) and that innervate expiratory motoneurons in the spinal cord (to decrease expiratory time). Studies will be performed in urethane-anesthetized rats in which we record extracellular single unit activity in the CNS, phrenic nerve activity, tidal volume, and systematic arterial pressure. Bronchopulmonary C fiber receptors will be stimulated by injecting PDG into the right atrium. The aims are: 1) to determine, using extracellular recording, if neurons in the NTS region (previously characterized; 6) receive excitatory input from bronchopulmonary C fiber receptors; 2) to determine the effects of bronchopulmonary C fiber receptor stimulation on the discharge patterns of early E cells (EDEC) in the rostral VRG and Botzinger complex, I cells throughout the VRG, and late E cells in the caudal VRG; and to determine, using antidromic activation, the projections of those cells, i.e. to the phrenic motor nucleus, thoracic spinal cord, vagus nerve, or the superior laryngeal nerve (SLN); 3) to determine, using cross-correlation analysis,