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

• 批准号: 7501504
• 负责人: MARK STEPHEN TAYLOR
• 金额: $ 25.73万
• 依托单位: UNIVERSITY OF SOUTH ALABAMA
• 依托单位国家: 美国
• 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/7501504
• 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

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。然而，内皮依赖的信号，尤其是内皮控制冠状动脉张力的潜在生理机制还知之甚少。我们最近已经证明，小电导钙激活的钾通道SK3是外周动脉内皮功能的基本控制器，促进持续扩张与其表达水平成正比。我们在冠状动脉中的初步数据表明，在生理压力和流量下，结构性SK3通道活动与稳态张力相反。我们现在已经发现，冠脉内皮细胞产生的重复性自发钙瞬变可能为SK3通道的激活提供基本刺激。特别是，这些钙信号靠近内弹力板(IEL)上的孔以及SK3通道和沿着内皮-血管平滑肌(VSM)界面表达的特定缝隙连接蛋白，表明存在局部的肌内皮信号复合体。我们假设，在冠状动脉的生理条件下，膜SK3通道的钙依赖重复激活驱动紧张性内皮细胞超极化，这种超极化通过IEL孔通过缝隙连接迅速传递到相邻的平滑肌。此外，我们认为雌激素诱导的内皮细胞SK3通道表达上调会放大这种内皮衍生的超极化(EDH)。为了充分解决这一假设，我们制定了两个具体目标。目的1将直接评估在完整的冠状动脉内皮细胞中自发的钙事件与SK3依赖的膜电位超极化的功能偶联，以及这种作用是否被SK3的不同表达(即通过直接的基因操作或雌激素)和切应力所改变。目的2将评估局部钙依赖的SK3激活IEL孔是否允许通过缝隙连接直接超极化内膜下VSM，从而减少VSM钙离子，促进冠状动脉扩张。为了实现这些目标，我们将应用最先进和创新的方法，包括1)在完整的冠状动脉中同时进行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)，其中SK3的表达可以通过实验控制来明确地识别SK3通道的特定影响，以及3)新型多肽抑制剂靶向特定的缝隙连接连接蛋白。这项工作将提供冠状动脉中基本的内皮信号和生理血管调节的范例，并为未来的CAD治疗确定潜在的细胞靶点。