Ca2+ Sparks as Regulators of Airway Contractility

Ca2 Sparks 作为气道收缩性的调节剂

• 批准号: 7061288
• 负责人: Ronghua ZhuGe
• 金额: $ 31.05万
• 依托单位: UNIV OF MASSACHUSETTS MED SCH WORCESTER
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-06-10 至 2008-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7061288
• 关键词: biosensor device; calcium channel; calcium flux; chloride channels; confocal scanning microscopy; genetically modified animals; ion transport; laboratory mouse; lung; membrane activity; membrane channels; membrane potentials; mitochondria; muscle cells; muscle contraction; muscle relaxation; potassium channel; receptor coupling; respiratory function; sarcoplasmic reticulum; smooth muscle; voltage gated channel

DESCRIPTION (provided by applicant): This project seeks to understand the mechanisms by which the contractility of airway smooth muscle (ASM) is controlled and regulated. The present proposal focuses on the highly localized and short-lived Ca2+ events (Ca2+ sparks), resulting from the opening of ryanodine receptors (RyRs) in the sarcoplasmic reticulum membrane, and their interactions with nearby Ca2+-activated ion channels in the plasma membrane. As in vascular smooth muscle, Ca2+ sparks activate a small number of large-conductance K+ (BK) channels in the spark microdomain to generate spontaneous transient outward currents (STOCs) which hyperpolarize the membrane in ASM. Recently we have identified another important target of Ca2+ sparks in ASM, i.e. Ca2+-activated CI- (CIca) channels which cause spontaneous transient inward currents (STICs) and thus depolarize the membrane. Accordingly, the central hypothesis of this proposal is that Ca2+ sparks coordinate the activation of membrane channels to regulate airway contractility. An integrated approach using high-speed digital Ca2+ imaging with simultaneous patch-clamping, and also 2D and 3D protein localization, will be applied using normal and transgenic mouse models. Furthermore, a physiological airway preparation, i.e., lung slices, will be employed to investigate the role of Ca2+ sparks in regulating contractility of airways themselves. Our specific objectives are to uncover the biophysics of RyRs underlying Ca2+ sparks using our newly developed signal mass approach (Aim 1); to determine the functional and spatial relationships of RyRs to BK channels and CIca channels (Aims 2 and 3); and to determine the physiological role of Ca2+ sparks in airways (Aim 4). We expect that these studies will provide new knowledge which could lead to development of novel therapeutic approaches for asthma and other bronchospasitc disorders.

描述（由申请人提供）：该项目旨在了解控制和调节气道平滑肌（ASM）收缩力的机制。目前的提案重点关注高度局部和短暂的 Ca2+ 事件（Ca2+ 火花），该事件是由于肌浆网膜中兰尼碱受体 (RyRs) 的开放引起的，以及它们与质膜中附近 Ca2+ 激活的离子通道的相互作用。与血管平滑肌一样，Ca2+ 火花激活火花微区中的少量大电导 K+ (BK) 通道，产生自发瞬态外向电流 (STOC)，使 ASM 中的膜超极化。最近，我们发现了 ASM 中 Ca2+ 火花的另一个重要目标，即 Ca2+ 激活的 CI- (CIca) 通道，它会引起自发瞬态内向电流 (STIC)，从而使膜去极化。因此，该提议的中心假设是Ca2+火花协调膜通道的激活以调节气道收缩性。使用高速数字 Ca2+ 成像和同步膜片钳以及 2D 和 3D 蛋白质定位的综合方法将应用于正常和转基因小鼠模型。此外，还将采用生理气道准备，即肺切片，来研究 Ca2+ 火花在调节气道本身收缩性中的作用。我们的具体目标是使用我们新开发的信号质量方法揭示 Ca2+ 火花背后的 RyRs 生物物理学（目标 1）；确定 RyR 与 BK 通道和 CIca 通道的功能和空间关系（目标 2 和 3）；并确定 Ca2+ 火花在气道中的生理作用（目标 4）。我们期望这些研究将提供新知识，从而开发出治疗哮喘和其他支气管痉挛疾病的新方法。