REGULATION OF VASCULAR SMOOTH MUSCLE Ca2+ SENSITIVITY

血管平滑肌 Ca2 敏感性的调节

• 批准号: 6537469
• 负责人: PAUL H RATZ
• 金额: $ 18.08万
• 依托单位: EASTERN VIRGINIA MEDICAL SCHOOL
• 依托单位国家: 美国
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-06-01 至 2003-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6537469
• 关键词: calcium indicator; calcium ion; fluorimetry; guanine nucleotide binding protein; laboratory rabbit; muscle contraction; muscle stimulant; muscle tone; neuromuscular transmission; protein kinase; vascular smooth muscle; vasomotion

Vascular smooth muscle (VSM) contractions are regulated at the subcellular level by two mechanisms, an elevation in [Ca2+], and an increase in the Ca2+ sensitivity of contractions. Ca2+ sensitivity may be increased by RhoA kinase (ROK)-induced inhibition of myosin light chain (MLC) phosphatase activity, and decreased by cell signals that activate MLC phosphatase activity. The importance of regulation of Ca2+ sensitivity is underscored by the recent finding that overactivity of Ca2+ sensitization is involved in the pathophysiology of hypertension. The long-term goal of my laboratory is to investigate subcellular mechanisms regulating VSM reactivity to contractile stimuli, focusing on regulation of Ca2+ sensitivity. I propose that one mechanism regulating Ca2+ sensitivity involves the recent history of contractile receptor stimulation. In short, prior strong receptor stimulation of VSM induces an adaptive response, termed memory, that temporarily reduces the ability of subsequent stimuli to elevate Ca2+ sensitivity. The proposed research project will use isolated rabbit arteries to 1) determine whether memory regulates myogenic tone in small arteries, and 2) elucidate how memory operates at the subcellular level. An increase in Ca2+ sensitivity plays a prominent role in regulation of myogenic tone, and aim 1 will test the hypothesis that memory reduces myogenic tone by reducing Ca2+ sensitivity. In the intact organism, such regulation would be expected to provide an overall increase in blood flow for some time after an episode of strong VSM contractile receptor stimulation that may occur during elevated sympathetic activity, or during blood vessel injury when vasoactive stimuli are released. These studies will be conducted using cannulated, pressurized small arteries. Aim 2 will test the hypothesis that memory reduces stimulus-induced Ca2+ sensitization by reducing ROK activation. An alternate hypothesis, that memory involves activation of a Ca2+ desensitization mechanism involving increased MLC phosphatase activity, will also be tested. Standard biomechanical and biochemical techniques will be employed, including simultaneous measurement of tissue isometric force and [Ca 2+]1 using front-surface fluorimetry and the Ca2+ indicator, fura-2. Collectively, these studies will provide new insights into the cellular mechanisms regulating Ca2+ sensitivity and VSM reactivity to contractile stimuli.

血管平滑肌（VSM）收缩通过两种机制在亚细胞水平调节，[Ca2+]的升高以及CA2+收缩敏感性的增加。 RhoA激酶（ROK）诱导的肌球蛋白轻链（MLC）磷酸酶活性的抑制作用可能会提高Ca2+敏感性，并通过激活MLC磷酸酶活性的细胞信号降低。最近的发现，CA2+敏化的过度活动与高血压的病理生理有关，因此强调了Ca2+敏感性调节的重要性。我实验室的长期目标是研究调节对收缩刺激的VSM反应性的亚细胞机制，重点是调节Ca2+灵敏度。我建议调节Ca2+灵敏度的一种机制涉及收缩受体刺激的近期历史。简而言之，先前的强受体刺激VSM诱导了一种自适应反应，称为记忆，从而暂时降低了随后刺激提高Ca2+灵敏度的能力。拟议的研究项目将使用孤立的兔动脉进行1）确定记忆是否调节小动脉中的肌源性张力，以及2）阐明记忆在亚细胞水平上的运作方式。 Ca2+敏感性的提高在调节肌吻合方面起着显着的作用，AIM 1将测试记忆通过降低Ca2+敏感性降低肌源音调的假设。在完整的生物体中，预计这种调节在升高交感神经活动期间可能发生的强烈VSM收缩受体刺激或血管损伤期间可能发生的强烈的VSM收缩受体刺激发作后，该调节会提供总体上升。这些研究将使用插管，加压的小动脉进行。 AIM 2将检验以下假设，即记忆通过减少ROK激活来减少刺激诱导的Ca2+敏化。一个替代假设，即记忆涉及激活涉及增加MLC磷酸酶活性的Ca2+脱敏机制。将采用标准的生物力学和生化技术，包括使用前表面荧光法和Ca2+指示器Fura-2同时测量组织等距力和[Ca 2+] 1。总的来说，这些研究将为调节CA2+敏感性和VSM对收缩刺激的反应性的细胞机制提供新的见解。