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）：压力引起的（肌源性）血管收缩是外周阻力设定和血流自动调节的关键。肌源性收缩取决于平滑肌 (SM) 膜去极化和电压依赖性 Ca2+ 内流。尽管肌源反应性是小动脉 SM 的固有特性，但它受到超极化和血管舒张影响的调节。 SM 中许多血管舒张刺激的重要介质是 Ca2+ 敏感的大电导 K+ 离子通道 (BKCa)。通过去极化和增加细胞内 [Ca2+] 激活 BKCa 已被提议作为“反馈”抑制剂，防止随着腔内压力增加而导致小动脉过度生肌收缩。这一假设主要基于在小脑动脉中进行的研究，但是我们的工作并不支持 BKCa 在调节骨骼肌小动脉的生肌张力方面具有相同的作用，骨骼肌小动脉是外周阻力的主要贡献者。有趣的是，我们的研究表明，骨骼肌小动脉和小脑动脉之间的 SM 膜电位和压力引起的收缩之间的关系存在根本差异，这表明骨骼肌血管中 BKCa 的激活可能会最小化，以允许在静息条件下持续的血管收缩。本提案研究的总体目标是明确 BKCa 在骨骼肌小动脉 SM 中的生理作用和调节机制。 BKCa 的控制是复杂的，其调节发生在分子和翻译后水平以及其相对于其他信号相关分子的细胞位置。这种复杂的调节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需求相匹配。因此，我们的总体假设是 BKCa 在血管 SM 中受到大脑和骨骼肌的差异调节。此外，BKCa 调节的这种区域差异允许血流动力学的局部控制与组织功能适当匹配。结合分子、细胞和电生理学方法，在骨骼肌和脑血管制剂中，拟议的研究旨在： 1. 检查 BKCa 的亚基组成和表达； 2. 使用 siRNA 敲低方法测试 BKCa 亚基在调节肌源性收缩中的作用； 3. 定义离体 SM 细胞中 BKCa 调节机制，重点是 Ca2+ 和电压敏感性；通过 cGMP/cGMP 依赖性蛋白激酶进行调节； 4.测试BKCa在调节离体血管的肌原性张力中的作用，重点关注张力的反馈调节和BKCa通道对cGMP/cGMP依赖性蛋白激酶和激活该第二信使系统的血管舒张机制的敏感性。了解调节 BKCa 功能的组织特异性机制将影响通道调节剂的设计和利用，这些通道调节剂是作为治疗血管疾病的治疗措施而开发的。公共健康相关性：这项研究将提高我们对小动脉如何改变其直径从而控制局部血流的认识。重要的是，获得的数据还将有助于识别在病理生理情况下可能改变的生化位点。因此，存在鉴定细胞信号转导步骤的潜力，这些步骤最终可用于靶向药物治疗。