MEMBRANE EXCITABILITY AND IONIC CURRENTS OF BARORECPTOR NEURONS

压力感受器神经元的膜兴奋性和离子电流

• 批准号: 6564797
• 负责人: MARK W CHAPLEAU
• 金额: $ 23.33万
• 依托单位: UNIVERSITY OF IOWA
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-01-01 至 2002-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6564797
• 关键词: autocrine; baroreceptors; carotid sinus; free radical oxygen; laboratory rabbit; laboratory rat; membrane potentials; neural transmission; neuropharmacology; neuroregulation; nitric oxide; oxidative stress; paracrine; potassium channel; prostacyclins; sodium channel; tissue /cell culture; voltage /patch clamp; voltage gated channel

The baroreceptor (BR) activity transmitted to the central nervous system is determined not only by the mechanoelectrical transducing channels but also by various voltage-gated channels that influence membrane excitability of BR neurons. Hypothesis #1: The important paracrine factors prostacyclin (PGI/2) and nitric oxide (NO) directly influence excitability of BR neurons through modulation of voltage-gated K+ and Na+ channels. Effects of PGI/2 and No on membrane potential, spike firing properties, and K+ and Na+ currents of isolated BR neurons in culture will be demonstrated using patch-clamp techniques. Experiments will define the intracellular signal transduction pathways and mechanisms by which PGI/2 and NO influence channel activity. Hypothesis #2: PGI/2 and NO function as autocrine factors produced endogenously in response to mechanical deformation and consequently modulate excitability and mechanosensitivity of the BR neurons. Release of PGI2 and NO from isolated neurons will be measured and their impact on excitability evaluated by pharmacological inhibitors and antagonists. The influence of expression of PGH and NO synthases within individual BR neurons and effects of changing expression using gene transfer on mechano-sensitivity will be investigated. Hypothesis #3: Intracellular generation of reactive oxygen species (ROS) significantly modulates excitability of BR neurons by altering K+ and Na+ currents. Effects of ROS on excitability and K+ and Na+ currently will be demonstrated and the intracellular mechanisms defined. Prolonged oxidative stress will be induced by incubation of BR neurons with oxidized LDL and the impact on membrane excitability and K+ and Na+ currents investigated. The in vivo relevance of the results obtained from isolated BR neurons will be confirmed, when possible, in experiments using the isolated carotid sinus-BR preparation.

压力感受器 (BR) 活性传递至中枢神经系统 不仅由机电转换通道决定，而且 还通过影响膜的各种电压门控通道 BR 神经元的兴奋性。假设#1：重要的旁分泌因素 前列环素 (PGI/2) 和一氧化氮 (NO) 直接影响兴奋性 通过电压门控 K+ 和 Na+ 通道调节 BR 神经元。 PGI/2 和 No 对膜电位、尖峰放电特性的影响， 培养物中分离的 BR 神经元的 K+ 和 Na+ 电流将是 使用膜片钳技术进行了演示。实验将定义 PGI/2 的细胞内信号转导途径和机制 NO 影响通道活动。假设#2：PGI/2 和 NO 的作用是 自分泌因子是对机械反应而内源产生的 变形并因此调节兴奋性和机械敏感性 BR 神经元。从分离的神经元中释放 PGI2 和 NO 测量并通过药理学评估它们对兴奋性的影响 抑制剂和拮抗剂。 PGH和NO表达的影响 单个 BR 神经元内的合成酶以及表达变化的影响 将研究使用基因转移对机械敏感性的影响。 假设#3：细胞内产生活性氧 (ROS) 通过改变 K+ 和 Na+ 显着调节 BR 神经元的兴奋性 电流。 ROS 对兴奋性以及 K+ 和 Na+ 的影响目前将是 证明并定义了细胞内机制。长时间氧化 通过将 BR 神经元与氧化的 LDL 一起孵育来诱导应激 研究了对膜兴奋性以及 K+ 和 Na+ 电流的影响。 从分离的 BR 神经元获得的结果的体内相关性 如果可能的话，将在使用分离的实验中得到证实 颈动脉窦-BR准备。