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）：内皮功能的丧失是冠状动脉疾病（CAD）发展的关键因素。尽管如此，对内皮依赖的信号传导，尤其是负责冠状动脉张力内皮控制的潜在生理机制。我们最近证明，小电导Ca2+激活的K+通道SK3是外周动脉中内皮功能的基本控制器，从而促进了与其表达水平成比例的持续扩张。我们在冠状动脉动脉中的初步数据表明，在生理压力和流动下，构成型SK3通道活性相反。现在，我们已经确定了在冠状动脉内皮细胞中产生的重复自发CA2+瞬变，这些瞬变可能为SK3通道激活提供了基本刺激。特别是，这些Ca2+信号与内部弹性层（IEL）以及沿着内皮血管 - 血管平滑肌（VSM）界面表达的特定间隙连接连接素的接近性以及特定的间隙连接连接素，这表明存在局部化的肌无内皮信号传导复合物。我们假设在冠状动脉的生理条件下，膜SK3通道的重复依赖Ca2+依赖性激活驱动滋补内皮性超极化，这通过IEL孔迅速传达给通过间隙连接的相邻平滑肌。此外，我们建议雌激素诱导的内皮SK3通道表达上调该内皮衍生的超极化（EDH）。为了充分解决这一假设，我们提出了两个具体目标。 AIM 1将直接评估完整冠状动脉内皮中自发性Ca2+事件与SK3依赖性膜电位超极化的功能耦合，以及是否通过差异SK3表达（即通过直接的遗传操纵或雌激素或雌激素）和剪切应力改变了这种作用。 AIM 2将评估IEL孔位点的局灶性Ca2+依赖性SK3激活是否可以通过间隙连接直接对下触觉VSM进行直接超极化，从而减少VSM Ca2+并促进冠状动脉扩张。为了追求这些目标，我们将采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振成像和细胞内电生理测量，2）独特的遗传小鼠模型（SK3T/T），在这种情况下，SK3表达可以在实验中具有针对性的特定对象，并具有针对性的特定对象。间隙连接连接素。这项工作将提供冠状动脉动脉中基本内皮信号传导和生理血管调节的范式，并确定对未来抗CAD疗法的潜在细胞靶标。