Chemotransduction in the Carotid Body

描述（由申请人提供）：颈动脉体（CB）位于颈内动脉附近，是检测动脉血中O2过少（缺氧）或CO2过多（高碳酸血症）或氢离子的唯一结构，并向大脑发出信号以产生几种呼吸和心血管反射反应。本研究拟进一步探讨CB通过缺氧和高碳酸血症来增加CB的神经输出（CBNO）的机制。从一个普遍接受的结构的器官和事件的化学转导过程中的顺序，我们将解决三个问题：（一）CB乙酰胆碱（ACh）和CB多巴胺（DA）之间的关系是什么？(b)相关的受体在哪里？(c)这些药物对CB球细胞（GC）的影响是什么？实验测试的假设，从整体的工作假设：乙酰胆碱是一个（）的主要兴奋性神经剂的CBNO的反应，缺氧和高碳酸血症的猫。猫已经表现出许多CB产生的反射反应，以及作为标准的CB的神经生理反应的特点。据报道，一氧化氮（NO）、ATP和腺苷（ADO）对CBNO对缺氧和高碳酸血症的反应有影响，因此对ACh的作用有影响。具体目标：（1）采用HPLC-ECD检测缺氧/高碳酸诱导离体灌流CB释放Ach和儿茶酚胺（CA）沿着CBNO的变化，以及NO、ATP和ADO对缺氧/高碳酸刺激CB的影响;（2）在颈动脉窦神经CB中定位多巴胺能和嘌呤能受体，（3）应用膜片钳技术观察DA、ATP和ADO对乙酰胆碱（ACh）诱导的大鼠岩神经节（PG）细胞膜电压和电流的影响，应用显微荧光技术观察其对[Ca ~（2+）]i的影响。已知患有几乎致命的哮喘发作的患者具有低反应性CB，而临界高血压患者具有高反应性CB。睡眠期间阻塞性呼吸暂停的减少取决于CB。通过更好地了解CB的转导过程，可能通过基因操作或具有高度集中效应的药物，可以大大改善这些情况的医疗管理。

DESCRIPTION (provided by applicant): The carotid body (CB), located near the internal carotid artery, is the only structure which detects too little O2 (hypoxia) or too much CO2 (hypercapnia) or hydrogen ion in the arterial blood, and signals the brain to produce several respiratory and cardiovascular reflex responses. This application proposes to explore further the mechanisms of CB's transduction of hypoxia and hypercapnia into increased the CB's neural output (CBNO). From a commonly accepted structure of the organ and sequence of events in the chemotransductive process we shall address three issues: (a) What is the relationship between CB acetylcholine (ACh) and CB dopamine (DA)? (b) Where are the pertinent receptors? (c) What is the impact of these agents back on the CB glomus cell (GC)? Experiments test hypotheses deriving from the overall working hypothesis: ACh is a (the) primary excitatory neuroagent for the CBNO's response to hypoxia and hypercapnia in the cat. The cat has exhibited many CB-generated reflex responses as well as serving as the norm for the CB's neurophysiological response characteristics. Nitric oxide (NO), ATP, and adenosine (ADO) are reported to have an effect on the CBNO's response to hypoxia and hypercapnia, and therefore on the role of ACh. SPECIFIC AIMS: (1) to measure the hypoxia-/hypercapnia- induced release of Ach and catecholamines (CAs) along with CBNO from the superfused CB in vitro with HPLC-ECD, and to measure the influence of NO, ATP, and ADO on the hypoxia- and hypercapnia-challenged CB; (2) to locate dopaminegic and purinergic receptors in the CB, the carotid sinus nerve, and in cell bodies of the petrosal ganglion (PG) with RT-PCR and immunocytochemistry; (3) to determine the effect of DA, ATP, and ADO on ACh-induced membrane voltages and currents of GCs with patch clamp, and the impact of these agents on [Ca2+]i with microfluorometry. Patients who have suffered near fatal asthma attacks are known to have hyporesponsive CBs, whereas borderline hypertensives have hyperresponsive CBs. Reduction of obstructive apneas during sleep depends on the CB. Medical management of these situations could be greatly improved with a better understanding of the CB's transductive processes, possibly with genetic manipulation or drugs with highly focused effects.