Coronary Artery Regulation by Small Conduction Ca2+-activated K+ Channels

小传导 Ca2 激活 K 通道对冠状动脉的调节

基本信息

批准号：
7315770
负责人：
MARK STEPHEN TAYLOR
金额：
$ 24.28万
依托单位：
UNIVERSITY OF SOUTH ALABAMA
依托单位国家：
美国
项目类别：
财政年份：
2007
资助国家：
美国
起止时间：
2007-09-30 至 2012-08-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7315770
关键词：
Accounting Address Arteries Arts Biology Blood Vessels Calcium-Activated Potassium Channel Cardiac Cardiovascular Diseases Cell membrane Communication Complex Condition Connexins Coronary Coronary Arteriosclerosis Coronary Circulation Coronary artery Coupling Data Depressed mood Development Endothelial Cells Endothelium Endothelium-Dependent Relaxing Factors Epoprostenol Estrogen Receptors Estrogens Event Female Functional disorder Future Gap Junctions Genetic Image Laboratories Localized Measurement Mediating Mediator of activation protein Membrane Membrane Potentials Nitric Oxide Peptides Peripheral Physiological Premenopause Prostaglandins I Protein Overexpression Regulation Research Personnel Role Signal Transduction Site Smooth Muscle Smooth Muscle Myocytes Speed Stimulus Up-Regulation Vascular Smooth Muscle Vasodilation Woman Work base cellular targeting density genetic manipulation in vivo inhibitor/antagonist innovation male mouse model novel pressure programs response shear stress voltage

项目摘要

DESCRIPTION (provided by applicant): Loss of endothelial function is a critical factor in the development of coronary artery disease (CAD). Still, endothelium dependent signaling and particularly the underlying physiological mechanism responsible for endothelial control of coronary artery tone are poorly understood. We have recently demonstrated that small conductance Ca2+-activated K+ channels, SK3, are fundamental controllers of endothelial function in peripheral arteries, promoting sustained dilation proportional to their level of expression. Our preliminary data in coronary arteries indicate that under physiological pressure and flow, constitutive SK3 channel activity opposes steady-state tone. We have now identified repetitive spontaneous Ca2+ transients generated in coronary endothelial cells that may provide the fundamental stimulus for SK3 channel activation. In particular, the proximity of these Ca2+ signals to holes in the internal elastic lamina (IEL) as well as to SK3 channels and specific gap junction connexins expressed along the endothelial-vascular smooth muscle (VSM) interface, suggest the existence of a localized myoendothelial signaling complex. We hypothesize that under physiological conditions in coronary arteries, repeated Ca2+-dependent activation of membrane SK3 channels drives tonic endothelial hyperpolarization, which is rapidly communicated through IEL holes to adjacent smooth muscle through gap junctions. Moreover, we propose that estrogen-induced upregulation of endothelial SK3 channel expression amplifies this endothelium-derived hyperpolarization (EDH). To fully address this hypothesis, we have formulated two specific aims. Aim 1 will directly assess the functional coupling of spontaneous Ca2+ events to SK3-dependent membrane potential hyperpolarization in the endothelium of intact coronary arteries and whether this effect is altered by differential SK3 expression (i.e. via direct genetic manipulation or estrogen) and shear stress. Aim 2 will assess whether focal Ca2+-dependent SK3 activation at sites of IEL holes allows for direct hyperpolarization of subintimal VSM via gap junctions, thereby reducing VSM Ca2+ and promoting coronary artery dilation. In pursuit of these aims, we will apply state-of-the-art and innovative approaches including 1) simultaneous high-speed confocal imaging and intracellular electrophysiological measurements in intact coronary arteries, 2) a unique genetic mouse model (SK3T/T) in which SK3 expression can be experimentally controlled to unequivocally discern the specific impact of SK3 channels, and 3) novel peptide inhibitors to target specific gap junction connexins. This work will provide a paradigm of fundamental endothelial signaling and physiological vasoregulation in coronary arteries, and identify potential cellular targets for future therapies against CAD.

描述（由申请人提供）：内皮功能丧失是冠状动脉疾病（CAD）发展的关键因素。尽管如此，人们对内皮依赖性信号传导，特别是负责内皮控制冠状动脉张力的潜在生理机制知之甚少。我们最近证明，小电导 Ca2+ 激活的 K+ 通道 SK3 是外周动脉内皮功能的基本控制器，促进与其表达水平成比例的持续扩张。我们在冠状动脉中的初步数据表明，在生理压力和流量下，组成型 SK3 通道活动与稳态张力相反。我们现在已经确定了冠状动脉内皮细胞中产生的重复自发 Ca2+ 瞬变，这可能为 SK3 通道激活提供基本刺激。特别是，这些 Ca2+ 信号与内弹性层 (IEL) 中的孔以及 SK3 通道和沿内皮-血管平滑肌 (VSM) 界面表达的特定间隙连接蛋白的接近，表明存在局部肌内皮细胞信号复合体。我们假设在冠状动脉的生理条件下，膜 SK3 通道的重复 Ca2+ 依赖性激活会驱动强直性内皮超极化，这种超极化通过 IEL 孔通过间隙连接快速传达到邻近的平滑肌。此外，我们认为雌激素诱导的内皮 SK3 通道表达上调会放大这种内皮源性超极化 (EDH)。为了充分解决这一假设，我们制定了两个具体目标。目标 1 将直接评估自发 Ca2+ 事件与完整冠状动脉内皮细胞中 SK3 依赖性膜电位超极化的功能耦合，以及这种效应是否因 SK3 差异表达（即通过直接基因操作或雌激素）和剪切应力而改变。目标 2 将评估 IEL 孔位点的局部 Ca2+ 依赖性 SK3 激活是否允许通过间隙连接直接超极化内膜下 VSM，从而减少 VSM Ca2+ 并促进冠状动脉扩张。为了实现这些目标，我们将应用最先进的创新方法，包括 1) 在完整冠状动脉中同步高速共聚焦成像和细胞内电生理测量，2) 独特的遗传小鼠模型 (SK3T/T)可以通过实验控制 SK3 表达，以明确辨别 SK3 通道的具体影响，以及 3）针对特定间隙连接蛋白的新型肽抑制剂。这项工作将为冠状动脉中的基本内皮信号传导和生理血管调节提供范例，并确定未来 CAD 治疗的潜在细胞靶点。