MEMBRANE EXCITABILITY AND IONIC CURRENTS OF BARORECPTOR NEURONS

压力感受器(BR)活动传递到中枢神经系统 不仅由机电转换通道决定，而且 也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 通过电压门控性钾离子通道和钠离子通道调节BR神经元。 前列环素/2和一氧化氮对膜电位、放电特性的影响 培养中分离的BR神经元的钾电流和钠电流 使用膜片钳技术进行演示。实验将定义 PGI/2的细胞内信号转导途径和机制 且不影响通道活动。假设2：PGI/2和NO作为 机械作用下内源性产生的自分泌因子 变形，从而调节兴奋性和机械敏感性 BR神经元的。从分离的神经元释放PGI2和NO将是 测量及其对兴奋性影响的药理学评价 抑制剂和拮抗剂。前列腺素H和一氧化氮表达的影响 单个BR神经元内的合成酶及其表达变化的影响 利用基因转移对机械敏感性进行研究。 假设3：细胞内产生的活性氧(ROS) 通过改变钾和钠显著调节BR神经元的兴奋性 洋流。ROS对兴奋性和K、Na的影响目前将 演示并定义了细胞内机制。长时间氧化 通过将BR神经元与氧化的低密度脂蛋白和 对膜兴奋性和钾、钠电流的影响进行了研究。 从分离的BR神经元获得的结果在体内的相关性 在可能的情况下，将在使用隔离的 颈动脉窦-BR准备。

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.