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， 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 BR神经元通过电压门控性K+和Na+通道的调节。 PGI/2和NO对细胞膜电位、峰电位发放特性 和K+和Na+电流的分离BR神经元在培养中将是 使用膜片钳技术证明。实验将定义 细胞内信号转导途径和机制，PGI/2 NO影响通道活性。假设#2：PGI/2和NO的功能是 自分泌因子是响应机械刺激而内源性产生的 变形，从而调节兴奋性和机械敏感性 的BR神经元。从分离的神经元释放的PGI 2和NO将是 通过药理学方法评价其对兴奋性的影响 抑制剂和拮抗剂。PGH和NO表达的影响 单个BR神经元内的过氧化物酶和改变表达的影响 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+显著调节BR神经元的兴奋性 水流活性氧对兴奋性和K+和Na+的影响，目前将 证明和细胞内机制的定义。延长氧化 应激将通过BR神经元与氧化的LDL孵育来诱导， 对膜兴奋性和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，将在实验中使用分离的 颈动脉窦-BR制备。

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.