Ionic currents in gastrointestinal smooth muscle

描述（由申请人提供）：本研究的长期目标是确定结肠炎症中离子通道活性的变化。溃疡性结肠炎是一种以反复发作的结肠炎症和组织变性为特征的炎症性肠病。要验证的主要假设是炎症诱导圆形平滑肌细胞内离子通道的特异性变化，导致细胞兴奋性和收缩性降低。初步数据显示，在实验性结肠炎右旋糖酐硫酸钠（DSS）模型小鼠结肠平滑肌肌细胞中，l型钙电流下调，atp敏感钾通道上调。特异性目的1是确定DSS处理小鼠结肠钙通道功能改变的细胞基础。在这个目的，我们将确定生物物理性质的变化，蛋白质和基因的表达和酪氨酸激酶的调节钙通道炎症。我们还将在钙通道的羧基端定义c-src激酶的最小结合域。在特定的目标中，我们将确定与atp敏感钾通道活性增强相关的机制。我们将确定构成该通道的亚型，并确定亚型表达水平随炎症的变化。具体目的3是确定整个组织段离子通道活性改变的功能影响。这一目标将整合炎症后单通道调节对整个组织功能的影响。初步数据表明，在单通道研究中观察到的对钾通道开放剂的敏感性增强与结肠平滑肌整个组织段的超极化增加有关。从这些研究中获得的信息将增加我们对炎症引起的离子通道活性潜在变化的理解，并有助于确定治疗结肠病理生理运动障碍的新药物。

DESCRIPTION (provided by applicant): The long-term goals of this study are to define the changes in ion channel activity in colonic inflammation. Ulcerative colitis is an inflammatory bowel disease characterized by recurrent episodes of colonic inflammation and tissue degeneration. The main hypothesis to be tested is that inflammation induces specific changes in ion channels within the circular smooth muscle cells resulting in decreased cell excitability and contraction. Preliminary data demonstrate down-regulation of L-type calcium currents and an up-regulation of the ATP-sensitive potassium channels in the murine colonic smooth muscle myocytes from the dextran sulphate -sodium (DSS) model of experimental colitis. Specific Aim 1 is to define the cellular basis of altered calcium channel function in the DSS -treated mice colon. In this aim, we will determine the changes in the biophysical properties, protein and gene expression and regulation by tyrosine kinase of the calcium channels with inflammation. We will also define the minimal binding domain for c-src kinase on the carboxy-terminus of the calcium channel. In specific aim, 2 we will determine the mechanisms associated with the enhanced activity of the ATP-sensitive potassium channel. We will identify the isoforms comprising this channel and define the changes in isoform expression levels with inflammation. Specific Aim 3 is to determine the functional effects of altered ion channel activity in whole tissue segments. This aim will integrate the findings of single channel modulation on whole tissue function following inflammation. Preliminary data indicate that enhanced sensitivity to the potassium channel openers observed in single channel studies correlate with increased hyperpolarization of whole tissue segments of colonic smooth muscle. The information obtained from these studies will increase our understanding of the potential changes in ion channel activity with inflammation and help identify novel therapeutic agents in the treatment of motility disturbances in the pathophysiology of the colon.