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: 6238980
• 负责人: ANDREAS CARL
• 金额: $ 16.04万
• 依托单位: UNIVERSITY OF NEVADA RENO
• 依托单位国家: 美国
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-05-01 至 1998-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6238980
• 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.

该项目的目标是阐明 K+ 的机制 通道控制圆形和机械的电气和机械活动 犬结肠的纵向平滑肌。 在初步 实验我们发现之前被表示为 “延迟整流器”K+电流由至少三个不同的 渠道类型。 此外，K/ATP 通道和 Ca2+ 激活的 K+ 通道 （BK 通道）存在于该组织中。 (1) 我们将检验电活动多样性的假设 胃肠道的模式是由于区域差异 这些 K+ 通道的类型和表达。 据此，我们将确定 “延迟整流器”的药理和动力学特性 电压钳位结肠肌细胞的成分及其单通道 细胞附着和切除的膜片的特性。 这些数据 对于将克隆和克隆的分子生物学研究联系起来至关重要 在完整组织中表达 K+ 观察通道。 戈伦霍芬 根据平滑肌组织的电特性对平滑肌组织进行了分类 阶段性（尖峰型和非尖峰型）和强直型活动模式 肌肉。 我们的实验将集中于呈现模型的组织 这三类中的每一类：我们将利用开发的协议 循环层结肠肌细胞（阶段性、非尖峰平滑肌） 研究 K+ 通道的类型和相对表达水平 纵向层结肠肌细胞（阶段性、尖峰平滑肌）和 下食管括约肌（强直平滑肌）。 (2) 我们将研究一氧化氮涉及的 K+ 电导和 β-肾上腺素能介导结肠肌肉组织的松弛。 对于两者 这些抑制性神经递质的证据已经获得 组织水平表明 K+ 通道的激活对于膜至关重要 超极化和随后的肌肉松弛。 然而，类型 K+ 通道参与这些行动尚不清楚。 我们将 研究通函中确定的 K+ 通道类型的监管 平滑肌细胞通过 cAMP 和 cGMP 介导的途径和蛋白激酶 C. 单渠道研究将阐明这些监管机制 途径。 这些研究将增进我们对电机制的了解 和胃肠道的机械节律性。