Anesthesia And Airways

描述（由申请人提供）：麻醉药对气道平滑肌（ASM）的复杂作用可能既有益处（例如，缓解哮喘患者的支气管痉挛），也有危害（例如，干扰与肺通气和灌注相匹配的正常机制）。本研究计划的总体目标是继续探索麻醉药如何影响气道。一些麻醉药通过降低给定浓度的胞质钙所产生的力（即降低钙敏感性）来部分地放松ASM，这是一种新的麻醉作用机制。本提案将通过追求两个具体目标，重点关注这种作用的机制，这在临床相关的麻醉浓度下是显着的。我们发现，一些（但不是全部）麻醉剂通过抑制gtp结合蛋白（G蛋白）的受体激活，在刺激ASM时降低钙敏感性。AIM A将通过首先定义调节猪气道钙敏感性的特异性受体- g蛋白途径，利用匀浆平滑肌和渗透平滑肌制备膜的免疫沉淀等技术，探索这种作用的机制。初步数据表明，麻醉作用于这些通路的部位对麻醉剂和通路都是特定的，然后将确定，重点是G蛋白及其相关受体的作用。AIM B将确定影响钙敏感性的麻醉药是否也影响纯化G蛋白的功能，检查鸟嘌呤核苷酸结合、GTPase活性和异三聚体G蛋白亚基中有或没有相关受体的蛋白质结合的生物物理参数。这些结果将与AIM A中获得的结果进行比较，以确保在分离蛋白中观察到的任何效应都与组织中的作用有关。由于这些G蛋白偶联受体信号通路在许多类型的细胞中是常见的，因此对ASM中这些麻醉机制的研究可能有助于了解其他器官系统中的麻醉作用。此外，控制钙敏感性的通路是治疗操作的潜在靶点，对这些系统和麻醉效果的探索可能促进新型支气管扩张剂的开发。

DESCRIPTION (provided by applicant): The complex effects of anesthetics on airway smooth muscle (ASM) have the potential for both benefit (e g , relief of bronchospasm in patients with asthma) and harm (e.g., interference with normal mechanisms matching lung ventilation and perfusion). The overall goal of this research program is to continue exploration of how anesthetics affect the airways. Some anesthetics relax ASM in part by decreasing the force produced for a given concentration of cytosolic calcium (i.e., decreasing calcium sensitivity), a novel mechanism of anesthetic action. This proposal will focus on the mechanisms responsible for this effect, which is significant at clinically relevant anesthetic concentrations, by pursuing two specific aims. We have found that some (but not all) anesthetics reduce calcium sensitivity during stimulation of ASM by inhibiting receptor activation of GTP-binding proteins (G proteins). AIM A will explore mechanisms responsible for this action by first defining the specific receptor-G protein pathways that regulate calcium sensitivity in porcine airways, using techniques such as immunoprecipitation in membrane preparations from homogenized smooth muscle and permeabilized smooth muscle preparations. The sites of anesthetic action on these pathways, which preliminary data suggest is specific both to anesthetic agent and to pathway, will then be determined, with emphasis on the role of G proteins and their associated receptors. AIM B will determine if the anesthetics which affect calcium sensitivity also affect the function of purified G proteins, examining guanine nucleotide binding, GTPase activity, and biophysical parameters of protein association in heterotrimeric G protein subunits with and without associated receptors. These results will be compared with those obtained in AIM A to ensure that any effects observed in isolated proteins are relevant to actions in tissues. Because these G protein-coupled receptor signaling pathways are common to many types of cells, investigation of these anesthetic mechanisms in ASM may yield insight into anesthetic actions in other organ systems. Also, pathways that control calcium sensitivity are a potential target for therapeutic manipulation, and exploration of these systems and anesthetic effects may facilitate the development of novel bronchodilators.