MECHANISMS OF CEREBRAL RESISTANCE ARTERY CONTRACTION

描述：(改编自申请)本提案的目的是 揭示去极化和收缩的一些机制 大脑动脉平滑肌对生理刺激的反应。中环 假设血管收缩刺激抑制K通道并激活 CL-通道，导致平滑肌去极化和收缩。 以下3个具体目标的目标是展示 脑动脉特异性钾离子通道和氯离子通道的参与 收缩反应，并定义细胞信号通路， 调节这些离子通道。 具体目标#1，将检验钙抑制的假设 钾通道激活是脑动脉收缩的机制之一。 钙可增强钙激活钾通道的活性。一 这种钙的来源是肌浆网，它通过 兰尼定敏感的通道将钙释放到心脏附近的局部区域 质膜。钙释放通道以及钙激活 钾通道本身是血管紧缩剂第二次产生的部位 信使能抑制钙激活的钾通道。这些 将使用激活剂和抑制剂来检查可能性 建立了信号转导通路。《特定目标2》将测试 假设电压依赖性钾通道的抑制是 激动剂引起血管收缩的另一种机制。药理作用 抑制电压依赖性钾通道可去极化和 收缩孤立的大脑动脉。电压依赖性钾通道 电流对血管平滑肌的静息膜电位有贡献。 在这一目标中，血管紧张剂的直接和间接作用 电压依赖性钾通道将被确定。具体目标#3 将检验氯离子通道有助于调节 脑动脉的膜电位。氯离子通道存在于 血管平滑肌。氯离子通道阻滞剂超极化和扩张 脑血管因激动剂或压力而收缩。在这个目标中， 的性质、调节机制和功能作用 将对脑血管平滑肌氯通道进行评估。这些 研究将使用最先进的技术来研究：1)本地化和 使用常规数字技术的细胞内钙离子的全球变化 荧光成像和共聚焦显微镜，2)离子通道活性使用 膜片钳技术及其与电和收缩的关系 加压脑阻力动脉的反应。一个更完整的 对血管收缩和松弛机制的认识 平滑肌对于制定新的治疗策略是必不可少的 涉及过度的病理生理状态的治疗 血管收缩(高血压、血管痉挛和缺血)。建议数 研究应提供与这些问题有关的重要新信息。

DESCRIPTION: (Adapted from the application) The aims of this proposal are to reveal some of the mechanisms of depolarization and constriction of cerebral artery smooth muscle to physiological stimuli. The central hypothesis is that vasoconstrictor stimuli inhibit K+ channels and activate Cl- channels, resulting in smooth muscle depolarization and contraction. The goals of the following 3 specific aims are to demonstrate the involvement of specific K+ and Cl- ion channels in cerebral artery constrictor responses and to define the cellular signaling pathways which regulate these ion channels. Specific Aim #1, will test the hypothesis that inhibition of calcium activated K+ channels is a mechanism of cerebral artery constriction. Calcium-activated potassium channel activity is increased by calcium. One source of this calcium is the sarcoplasmic reticulum which via ryanodine-sensitive channels releases calcium to localized regions near the plasmalemma. The calcium release channels as well as the calcium-activated potassium channel itself are sites where vasoconstrictor generated second messengers could inhibit calcium-activated potassium channels. These possibilities will be examined using activators and inhibitors of established signal transduction pathways. Specific Aim #2 will test the hypothesis that inhibition of voltage-dependent potassium channels is another mechanism of agonist-induced vasoconstriction. Pharmacological inhibition of voltage-dependent potassium channels depolarizes and constricts isolated cerebral arteries. Voltage-dependent potassium channel currents contribute to resting membrane potential in vascular smooth muscle. In this aim the direct and indirect effects of vasoconstrictors on voltage-dependent potassium channels will be determined. Specific Aim #3 will test the hypothesis that chloride channels contribute to regulation of membrane potential in cerebral arteries. Chloride channels are present in vascular smooth muscle. Chloride channel blockers hyperpolarized and dilate cerebral arteries contracted by agonists or pressure. In this aim, the properties and mechanisms of regulation and functional roles of cerebrovascular smooth muscle chloride channels will be evaluated. These studies will employ state-of-the-art techniques to study: 1) localized and global changes in intracellular calcium using conventional digital fluorescence imaging and confocal microscopy, 2) ion channel activity using the patch-clamp technique and 3) correlated electrical and contractile responses of pressurized cerebral resistance arteries. A more complete understanding of the mechanisms of contraction and relaxation of vascular smooth muscle is essential to the development of new strategies for treatment of pathophysiological states that involve excessive vasoconstrictor (hypertension, vasospasm and ischemia). The proposed studies should provide essential new information relevant to these issues.