Anesthesia And Airways

描述(由申请人提供)：麻醉药对呼吸道平滑肌(ASM)的复杂影响既有好处(例如，缓解哮喘患者的支气管痉挛)，也有损害(例如，干扰匹配肺通风和灌注的正常机制)。这项研究计划的总体目标是继续探索麻醉药如何影响呼吸道。一些麻醉剂通过减少细胞内一定浓度的钙所产生的力(即降低钙敏感性)来部分地松弛ASM，这是一种新的麻醉作用机制。这项提案将通过追求两个特定的目标，将重点放在导致这种效应的机制上，这在临床相关的麻醉剂浓度上是重要的。我们已经发现，一些(但不是所有)麻醉药通过抑制GTP结合蛋白(G蛋白)的受体激活来降低刺激ASM时的钙敏感性。目的A将通过免疫沉淀等技术，首先确定调节猪呼吸道钙敏感性的受体-G蛋白通路，从而探讨这一作用的机制。然后将确定这些通路上的麻醉作用部位，初步数据表明这些作用是麻醉剂和通路所特有的，重点是G蛋白及其相关受体的作用。目的确定影响钙敏感性的麻醉药是否也影响纯化的G蛋白的功能，检测具有和不具有相关受体的异源三聚体G蛋白亚基的鸟核苷酸结合力、GTP酶活性和蛋白质结合的生物物理参数。这些结果将与在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影响都与组织中的作用相关。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共同的，对ASM中这些麻醉机制的研究可能有助于深入了解其他器官系统的麻醉作用。此外，控制钙敏感性的通路是治疗操作的潜在靶点，探索这些系统和麻醉效果可能会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.