Ion Channels in Mechanosensitive Neurons

描述(申请人提供)：本项目的长期目标是了解机械感觉信息从压力感受器感觉终末到孤束核中央终末的产生和传输。这是一项更广泛的研究工作的一部分，目的是确定神经生理和神经解剖学基础，后者是动脉压和心率神经调节的基础。在这项资助中，我们正在研究一种新的离子通道家族--TRPC钙离子通透性阳离子通道家族的分布和功能。这些通道很重要，因为它们是钙内流的来源，有望通过影响膜电位、中央终末的递质释放和外周终末的感觉放电来调节神经元的活动模式。有四个具体目的：第一，研究TRPC通道在压力感受性传入纤维中的分布。用免疫组织化学方法，我们将确定TRPC通道在压力感受器传入通路中的三个区域：主动脉弓内有髓纤维和无髓纤维的外周感觉受体，结状神经节中的胞体和孤束核中的突触终末。在第二个目的中，我们将通过对细胞贴附斑块中的通道和穿孔斑片全细胞记录中的全细胞电流的电生理学特征来询问是什么配体激活了这些通道。在第三个目标中，我们通过检测激动剂对钙内流的影响来探讨激活机制，利用钙成像技术来评估TRPC通道相对于电压门控通道的贡献。最后，在第四个目标中，我们探讨了激活特定的TRPC通道在全细胞电压记录中的功能后果。这些研究将包括消除特定通道的RNA干扰。

DESCRIPTION (provided by applicant): The long-term objective of this project is to understand the generation and transmission of mechanosensory information from the baroreceptor sensory terminal to its central termination in the nucleus of the solitary tract. This is part of a broader research effort to determine the neurophysiological and neuroanatomical substrate that underlies neural regulation of arterial pressure and cardiac rhythm. In this grant we are examining the distribution and the function of a new family of ion channels, the TRPC family of calcium permeable cation channels. These channels are important because they serve as a source of calcium influx that is expected to modulate the pattern of neuronal activity through effects on membrane potential, transmitter release at the central terminals and sensory discharge at the peripheral terminals. There are four specific aims: the first examines the distribution of the TRPC channels in the baroreceptor afferent fibers. Using immunohistochemistry, we will define the location of TRPC channels in the baroreceptor afferent pathway in three regions: the peripheral sensory receptors of myelinated and unmyelinated fibers in the arch of the aorta, in their soma in the nodose ganglion and in their synaptic terminals in the nucleus of the solitary tract. In the second aim we will ask what ligands activate these channels using an electrophysiological characterization of the channels in cell-attached patches and whole cell current in perforated patch whole cell recording. In the third aim we pursue the mechanism of activation by examining the effect of agonist on calcium influx using calcium imaging techniques to evaluate the contribution of the TRPC channels relative to the voltage-gated channels. Finally, in aim four we explore the functional consequence of activation of specific TRPC channels in whole cell voltage recording. These studies will include RNA interference to eliminate specific channels.