STIMULUS SECRETION COUPLING IN CAROTID BODY GLOMUS CELLS

颈动脉体球细胞的刺激分泌耦合

• 批准号: 2029294
• 负责人: DAVID F. DONNELLY
• 金额: $ 16万
• 依托单位: YALE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-12-01 至 1998-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2029294
• 关键词: acidosis; afferent nerve; calcium channel; calcium flux; carotid body; catecholamines; chemoreceptors; enzyme activity; hypoxia; laboratory rat; microelectrodes; nucleotides; phosphorylases; potassium channel; secretion; sodium channel; synaptic vesicles; voltage /patch clamp

The primary sensor of the respiratory and cardiovascular systems for hypoxia are the carotid body chemoreceptors which increase their activity in response to a decrease in PaO2 or PHa. Sensitivity to these stimuli are weak at birth and increase over the first week or two of life. Hypoxia and acidity are likely transduced by glomus cells, secretory cells in apposition to the afferent nerve endings. Their role is essential to chemotransduction because chemosensitivity is lost following separation of the glomus cell from the nerve endings. Recent patch clamp recordings of isolated glomus cells revealed a K+ current which is inhibited by hypoxia. This inhibition is hypothesized to play an essential role in the transduction cascade of hypoxia, leading to depolarization, calcium influx and enhanced transmitter release. However, our preliminary question the validity of this mechanism because hypoxia often fails to alter membrane currents of glomus cells, in situ, and K+ blocking agents, although greatly effecting the cellular currents, may not block the nerve or secretory response of the organ. The proposed experiments address two basic questions regarding the transduction process. Firstly, what is the identity of glomus cell secretogues and which are liberated during hypoxia? This is addressed by examining: i) the importance of Na+, K+ and Ca+2 channels in initiating glomus cells secretion, ii) the relationship between Ca+2i and cell secretion and iii) the modulatory role of nucleotides and phosphorylases on secretory activity. Secondly, what change occurs in the level of or sensitivity to secretogues to account for the developmental increase in glomus cell stimulus/secretion coupling? The proposed experiments will employ a new and unique chemoreceptor model which allows for simultaneous single-fiber nerve recordings and either measurement of catecholamine release or patch-clamp recording of glomus cell. Patch-clamp data is used for assessment of vesicular fusion events by high-resolution monitoring of membrane capacitance. Catecholamine secretion is measured using carbon-fiber, Nafion coated microelectrodes combined with scanning or amperometric voltammetry. The anticipated results from this work will allow us to better understand the mechanisms of glomus cell hypoxia and acidity transduction and the basis for the maturational increase in sensitivity to these physiologic stimuli. This may lead to therapeutic strategies that can alter chemosensitivity and thereby improve treatment of apnea and hypoventilation in the neonate and older subject.

呼吸道和心血管系统的主要传感器 缺氧是增加活性的颈动脉体化学感受器 响应PAO2或PHA的减少。对这些刺激的敏感性是 出生时弱，在第一周或两周的生活中增加。缺氧和 酸度可能被Glomus细胞转导，分泌细胞 对传入神经结尾的申请。他们的角色对于 化学转导，因为分离后化学敏度失去了 神经末端的肾小球细胞。最近的补丁夹录音 分离的Glomus细胞揭示了缺氧抑制的K+电流。 假设这种抑制作用在 缺氧的转导级联，导致去极化，钙涌入钙 并增强发射器释放。但是，我们的初步问题 这种机制的有效性，因为缺氧通常无法改变膜 肾小球细胞的电流，原位和K+阻断剂，尽管 极大地影响细胞电流，可能不会阻止神经或 器官的分泌反应。 拟议的实验解决了有关 转导过程。首先，肾小球细胞的身份是什么 在缺氧期间解放的秘诀？这是由 检查：i）Na+，K+和Ca+2个频道在启动中的重要性 Glomus细胞分泌，ii）CA+2i与细胞之间的关系 分泌和iii）核苷酸和磷酸酶的调节作用 关于分泌活动。其次，在或在 对秘密的敏感性，以解释 Glomus细胞刺激/分泌耦合？ 提出的实验将采用新的独特的化学感受器模型 这允许同时进行单纤维神经记录，要么 glomus的儿茶酚胺释放或斑块钳记录的测量 细胞。贴片钳数据用于评估小囊泡融合事件 通过高分辨率监测膜电容。儿茶酚胺 分泌是使用碳纤维，Nafion涂层微电极测量的 结合扫描或安培伏安法。 这项工作的预期结果将使我们能够更好地理解 Glomus细胞缺氧和酸度转导的机制以及 对这些生理的敏感性成熟的基础 刺激。这可能会导致可以改变的治疗策略 化学敏感性，从而改善呼吸暂停的处理 新生儿和较旧受试者的不足。