MOLECULAR AND FUNCTIONAL ANALYSIS OF COLONIC IONIC CONDUCTANCES

结肠运动的调节与结肠平滑肌和非肌肉细胞表达的离子电导的调节密切相关。该项目的长期目标是更全面地了解离子电导在调节结肠运动中的作用。对这些电导成分的分子鉴定将有助于分析它们的调节和受体介导的调节。此外，这些信息将为识别或开发可能作用于这些渠道的治疗方法提供基础。在表达系统中研究这些电导和开发阻断药物比在天然的GI肌肉细胞中容易得多。该项目将重点研究天然结肠细胞中的离子电流与其分子对应的离子电流之间的关系。我们将利用从确定这种关系中获得的信息来研究：(1)特定离子通道在结肠电活动中的作用，(2)这些通道是如何响应神经元和激素输入而调节的，(3)离子通道在结肠中的细胞和亚细胞分布。这些实验是基于在上一次资助期间在结肠离子通道的分子识别方面取得的几项重要进展。我们将在这项研究中提出几个假设。一个目的是研究克隆的Kv通道与自然结肠电活动之间的关系。我们还提出Trp基因家族的成员编码结肠非选择性阳离子电流，该电流是结肠兴奋性神经传递的中枢。我们将测试Kir3.1/3.2编码I/KACH在结肠中的假设，对兴奋性反应造成超极化影响。我们将确定结肠离子通道是否可以作为调节通路的靶点，以便对天然细胞和组织进行可测试的预测。最后，我们将确定几种K+通道在结肠肌肉和非肌肉细胞中的细胞和亚细胞分布。

Regulation of colonic motility is intimately coordinated with the modulation of ionic conductances expressed in colonic smooth muscle and non-muscle cells. The long-term goal of this project is to gain a more complete understanding of the role of ionic conductances in regulating colonic motility. The molecular identification of the components for these conductances will aid in the analysis of their modulation and receptor mediated regulation. In addition, this information will provide a foundation for the identification or development of therapeutics that might act on these channels. It is much easier to study these conductances and develop blocking drugs in expression systems than in native GI muscle cells. This project will focus on the relationship between ionic currents in native colon cells and their molecular counterparts. We will use the information gained from determining this relationship to study: (1) the role of specific ion channels in colonic electrical activity, (2) how these channels are regulated in response to neuronal and hormonal input, (3) the cellular and subcellular distribution of ion channels in the colon. The experiments are based upon several important advances in the molecular identification of colonic ion channels made during the previous funding period. We will address several hypotheses in this study. One aim focuses on the relationship between cloned Kv channels and native colonic electrical activity. We also propose that members of the trp gene family encode the colonic non-selective cation current, central to excitatory neurotransmission in the colon. We will test the hypotheses that Kir3.1/3.2 encodes I/KACh in the colon, contributing a hyperpolarizing influence on the excitatory response. We will determine whether colonic ion channels can be targets on regulatory pathways in order to make testable predictions for native cells and tissues. Finally, we will determine the cellular and subcellular distribution of several K+ channels in colon muscle and non-muscle cells.