PHYSIOLOGY OF VOLTAGE DEPENDENT POTASSIUM CHANNELS IN COLONIC MUSCLES

结肠肌肉中电压依赖性钾通道的生理学

• 批准号: 6270681
• 负责人: ANDREAS CARL
• 金额: $ 16.52万
• 依托单位: UNIVERSITY OF NEVADA RENO
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-05-01 至 1999-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6270681
• 关键词: biological signal transduction; cell differentiation; colon; cyclic AMP; cyclic GMP; electrical measurement; electrophysiology; esophagogastric junction; gastrointestinal motility /pressure; isoproterenol; nitric oxide; organ culture; potassium channel; protein kinase C; smooth muscle; voltage /patch clamp

The goal of this Project is to clarify the mechanisms by which K+ channels control the electrical and mechanical activity of circular and longitudinal smooth muscle of the canine colon. In preliminary experiments we have found that what previously has been denoted as "delayed rectifier" K+ current is composed of at least three distinct channel types. In addition K/ATP channels and Ca2+-activated K+ channels (BK channels) are present in this tissue. (1) We will test the hypothesis that the diversity of electrical activity patterns in the gastrointestinal tract is due to regional differences in type and expression of these K+ channels. Accordingly, we will determine the pharmacological and kinetic properties of "delayed rectifier" components in voltage clamped colonic myocytes and their single channel properties in cell-attached and excised membrane patches. These data will be essential to link molecular biology studies of cloned and expressed K+ channels to observations in the intact tissue. Golenhofen has classified smooth muscle tissues according to their electrical activity patterns in phasic (spiking and non-spiking types) and tonic muscles. Our experiments will focus on tissues that present models of each of these three classes: We will utilize the protocols developed on circular layer colonic myocytes (phasic, non-spiking smooth muscle) to investigate the types and relative expression levels of K+ channels in longitudinal layer colonic myocytes (phasic, spiking smooth muscle) and the lower esophageal sphincter (tonic smooth muscle). (2) We will investigate the K+ conductances involved in nitric oxide and Beta-adrenergic mediated relaxation of the colonic musculature. For both of these inhibitory neurotransmitters evidence has been obtained on the tissue level that activation of K+ channels is essential for the membrane hyperpolarization and subsequent muscle relaxation. However the type of K+ channel involved in either of these actions is not known. We will investigate regulation of the K+ channel types identified in circular smooth muscle cells by cAMP and cGMP mediated pathways and protein kinase C. Single channel studies will clarify the mechanism of these regulatory pathways. These studies will advance our knowledge of the mechanisms of electrical and mechanical rhythmicity in the gastrointestinal tract.

本项目的目标是阐明K+ 通道控制循环的电和机械活动， 犬结肠的纵向平滑肌。 初步 实验中，我们发现，以前被称为 “延迟整流”钾离子电流由至少三个不同的 频道类型 此外，K/ATP通道和Ca 2+激活的K+通道 (BK通道）存在于该组织中。 (1)我们将检验脑电活动的多样性 胃肠道的模式是由于区域差异， 这些K+通道的类型和表达。 因此，我们将确定 “延迟整流”的药理学和动力学特性 电压钳位结肠肌细胞的成分及其单通道 在细胞附着和切除的膜补丁的属性。 这些数据 将是必不可少的链接克隆的分子生物学研究， 表达的K+通道与完整组织中的观察结果一致。 戈伦霍芬 根据平滑肌组织的电生理特性， 阶段性（尖峰和非尖峰类型）和紧张性的活动模式 肌肉. 我们的实验将集中在组织，目前的模型， 这三类中的每一类：我们将利用在 环形层结肠肌细胞（阶段性，非尖峰平滑肌）， 研究K+通道的类型和相对表达水平， 纵层结肠肌细胞（阶段性，尖峰平滑肌）和 下食管括约肌（紧张性平滑肌）。 (2)我们将研究一氧化氮中涉及的K+电导， β-肾上腺素能介导的结肠肌肉松弛。 为 这些抑制性神经递质的证据已经获得了对 组织水平，K+通道的激活对于膜是必不可少的 超极化和随后的肌肉松弛。 然而， K+通道参与这两种作用的任何一种都是未知的。 我们将 研究循环中确定的K+通道类型的调节 平滑肌细胞通过cAMP和cGMP介导的途径和蛋白激酶 C. 单通道研究将阐明这些调节的机制 途径。 这些研究将推进我们对电生理机制的认识。 和胃肠道的机械节律。