ION CHANNELS IN MECHANOSENSITIVE NEURONS

我们正在研究电压门控离子通道在压力感受器神经元的胞体和终端的表达，其机械敏感终端位于大动脉壁的外膜。我们已经提出，这些通道是连接无髓纤维和有髓纤维的受体对动脉压力变化作出反应时明显不同的放电模式的基础。特别是，本提案侧重于识别，随后的功能评估，特定的电压门控钾通道。这些通道形成动作电位和放电模式，是神经调节剂的常用靶点。在第一个目标中，我们将通过使用RT-PCR，原位杂交和通道特异性抗体来确定钾通道家族的哪些成员，Kvl, Kv2， Kv3和Kv4存在于压力受体神经元的体细胞中。在目标二中，我们将转向外周末梢，即实际的压力感受器，来探究存在于体细胞中的通道是否也存在于外周末梢。我们将使用共聚焦显微镜使用免疫细胞化学技术来探索有髓和无髓纤维终端内离子通道的分布。在目标3中，我们将研究特定钾通道的功能作用。为了做到这一点，我们在已识别的压力感受器神经元中使用反义策略。一个不同的通道对静息膜电位、动作电位和去极化产生的放电的贡献将被检查。最后，在AIMS 4中，我们将在数学模型中结合AIMS 1-3中确定的通道的解剖定位的电生理特征，使我们能够对这些通道A和C压力感受器神经元的作用做出可测试的预测。

We are studying the expression of voltage-gated ion channels in the soma and terminals of baroreceptor neurons whose mechanosensitive terminals lie in the adventitia of walls of major arteries. We have proposed that these channels underlie the markedly different firing patterns of the receptors connected to unmyelinated versus myelinated fibers as they respond to changes in arterial pressure. In particular, this proposal focuses on the identification, followed by functional assessment, of the specific voltage-gated potassium channels. These channels shape the action potential and discharge patterns and they are frequent targets of neuromodulators. In the first aim we will determine which of the members of the potassium channel families, Kvl, Kv2, Kv3 and Kv4, are present in the soma of baroreceptor neurons through the use of RT-PCR, in situ hybridization and channel specific antibodies. In aim two we will move to the peripheral terminal, the actual baroreceptor, to ask whether the channels that are present in the soma are also present on the peripheral terminals. We will use immunocytochemical techniques to explore the distribution of the ion channels within the terminals of both myelinated and unmyelinated fibers using confocal microscopy. In Aim 3 we will examine the functional role of the specific potassium channels. To do this we are using anti-sense strategy in identified baroreceptor neurons. The contributions of a distinct channel to resting membrane potential, action potential and to the discharge produced by depolarization will be examined. Finally, in Aim 4 we will tie together the electrophysiological characterization with anatomical localization of the channels identified in AIMS 1-3 in mathematical models that allow us to make testable predictions for the role of each of these channels A and C baroreceptor neurons.