Signaling Mechanisms Underlying Myogenic Tone in Arterioles of Skeletal Muscle: R

骨骼肌小动脉肌源性张力的信号机制：R

• 批准号: 7894808
• 负责人: Michael A HILL
• 金额: $ 36.35万
• 依托单位: UNIVERSITY OF MISSOURI-COLUMBIA
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-07-17 至 2013-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7894808
• 关键词: Affect; Animals; Appearance; Arteries; Behavior; Biochemical; Blood Vessels; Blood flow; Caliber; Caveolae; Cells; Cerebrum; Characteristics; Complement; Complex; Coupling; Cyclic GMP; Cyclic GMP-Dependent Protein Kinases; Data; Diabetes Mellitus; Drug Delivery Systems; Elements; Endothelium; Endothelium-Dependent Relaxing Factors; Feedback; Genes; Goals; Heterogeneity; Homeostasis; Hyperglycemia; Hypertension; In Situ; In Vitro; Ion Channel; Knowledge; Laboratories; Location; Measures; Mediating; Mediator of activation protein; Membrane; Membrane Potentials; Messenger RNA; Metabolic; Microcirculation; Molecular; Peripheral Resistance; Phosphorylation; Physiological; Post-Translational Protein Processing; Potassium Channel; Preparation; Probability; Property; Protein Kinase; Proteins; RNA Splicing; Rattus; Regulation; Relative (related person); Reliance; Research Personnel; Resistance; Rest; Role; Second Messenger Systems; Signal Transduction; Site; Skeletal Muscle; Small Interfering RNA; Smooth Muscle; Smooth Muscle Myocytes; Stimulus; Testing; Therapeutic; Tissues; Variant; Vascular Diseases; Vascular Smooth Muscle; Vascular resistance; Vasodilation; Vasodilator Agents; Work; arteriole; base; caveolin 1; cerebral artery; constriction; cremaster muscle; density; design; hemodynamics; iberiotoxin; improved; inhibitor/antagonist; insight; mRNA Expression; pressure; prevent; public health relevance; regional difference; research study; vasoconstriction; voltage

DESCRIPTION (provided by applicant): Pressure-induced (myogenic) vasoconstriction is key to setting of peripheral resistance and autoregulation of blood flow. Myogenic constriction depends on smooth muscle (SM) membrane depolarization and voltage- dependent Ca2+-influx. Although myogenic responsiveness is an inherent property of arteriolar SM, it is modulated by hyperpolarizing and vasodilator influences. An important mediator of a number of vasodilator stimuli in SM is the Ca2+-sensitive large-conductance K+ ion channel (BKCa). Activation of BKCa by depolarization and increased intracellular [Ca2+] has been proposed to serve as a 'feedback' inhibitor, preventing excessive myogenic constriction of arterioles as intralumenal pressure increases. This hypothesis is largely based on studies performed in small cerebral arteries, however our work does not support an identical role for BKCa in regulating myogenic tone of skeletal muscle arterioles, which are a major contributor to peripheral resistance. Interestingly, our studies suggest a fundamental difference between skeletal muscle arterioles and small cerebral arteries in the relationship between SM membrane potential and pressure-induced constriction suggesting that in skeletal muscle vessels BKCa activation may be minimized to allow sustained vasoconstriction under resting conditions. The overall goals of the studies in this proposal are to define the physiological role and mechanisms of regulation for BKCa in arteriolar SM of skeletal muscle. Control of BKCa is complex with regulation occurring at the molecular and post-translational levels as well as by its cellular location with respect to other signaling-related molecules. This complexity of regulation provides extensive opportunity for tissue-specific heterogeneity where channel behavior is matched to local tissue requirements. Thus, our overall hypothesis is that BKCa is differentially regulated in vascular SM from cerebral and skeletal muscle. Further, such regional differences in regulation of BKCa allow for local control of hemodynamics to be appropriately matched to tissue function. Using a combination of molecular, cellular and electrophysiological approaches, in skeletal muscle and cerebral vascular preparations, the proposed studies aim to: 1. examine subunit composition and expression of BKCa; 2. test the role of BKCa subunits in modulating myogenic constriction using an siRNA knockdown approach; 3. define mechanisms of BKCa regulation in isolated SM cells with emphasis on Ca2+ and voltage sensitivity; modulation by cGMP/cGMP-dependent protein kinase; 4. test the role of BKCa in modulating myogenic tone of isolated vessels, focusing on both feedback-modulation of tone and the sensitivity of the BKCa channel to cGMP/cGMP- dependent protein kinase and vasodilator mechanisms activating this second messenger system. Understanding tissue-specific mechanisms by which BKCa function is regulated will impact on design and utilization of channel modulators developed as therapeutic measures for treatment of vascular diseases. PUBLIC HEALTH RELEVANCE: This study will improve our knowledge of how small arteries can vary their diameters and thus control local blood flow. Importantly, the data obtained will also contribute to identifying biochemical sites that may be altered in pathophysiological situations. Thus the potential exists for the identification of steps in cellular signaling that may ultimately be used for the targeting of pharmacological therapies.

描述（由申请人提供）：压力诱导的（肌源性）血管收缩是设定外周耐药性和血流自动调节的关键。肌源性收缩取决于平滑肌（SM）膜去极化和依赖电压的Ca2+-influx。尽管肌源性反应性是小动脉SM的固有特性，但它受到超极化和血管舒张剂影响的调节。 SM中许多血管扩张刺激的重要介质是Ca2+敏感的大传导k+离子通道（BKCA）。已经提出，通过去极化和细胞内[Ca2+]增加的BKCA激活作为“反馈”抑制剂，随着赤道压力的增加，小动脉的肌源性过多。该假设很大程度上基于在小脑动脉中进行的研究，但是我们的工作不支持BKCA在调节骨骼肌小动脉的肌源性方面的相同作用，这是外周耐药性的主要因素。有趣的是，我们的研究表明，骨骼肌小动脉与小脑动脉之间的基本差异在SM膜电位与压力引起的收缩之间的关系中，这表明在骨骼肌血管中，BKCA激活可能可以最小化以允许在静止条件下进行持续的血管收缩。该提案中研究的总体目标是定义BKCA在骨骼肌中BKCA调节的生理作用和机制。 BKCA的控制是复杂的，调节在分子和翻译后水平以及与其他信号相关的分子相对于其细胞位置。这种调节的复杂性为组织特异性异质性提供了广泛的机会，其中通道行为与局部组织的需求相匹配。因此，我们的总体假设是BKCA在脑和骨骼肌的血管SM中受到差异调节。此外，这种区域在BKCA调节方面的差异允许对血液动力学的局部控制与组织功能适当匹配。使用分子，细胞和电生理方法，骨骼肌和脑血管制剂的组合，拟议的研究旨在：1。检查BKCA的亚基组成和表达； 2。测试BKCA亚基在使用siRNA敲低方法调节肌源性收缩中的作用； 3。定义分离的SM细胞中BKCA调节的机制，重点是Ca2+和电压敏感性； CGMP/CGMP依赖性蛋白激酶的调节； 4。测试BKCA在调节孤立血管的肌源音方面的作用，重点介绍了音调的反馈调节以及BKCA通道对CGMP/CGMP依赖性蛋白激酶激酶和血管音证机制的敏感性，都激活了这一第二Messenger系统。了解BKCA功能受调节的组织特异性机制将影响开发的通道调节剂的设计和利用，作为治疗血管疾病的治疗方法。公共卫生相关性：这项研究将提高我们对小动脉如何改变其直径的知识，从而控制局部血流。重要的是，获得的数据还将有助于确定在病理生理情况下可能改变的生化部位。因此，存在可能最终用于靶向药理疗法的细胞信号传导中的步骤的潜力。