ACTIONS OF INHALATIONAL ANESTHETICS ON CELL MEMBRANES

吸入麻醉剂对细胞膜的作用

• 批准号: 3305830
• 负责人: JOHN J FRANKS
• 金额: $ 28.71万
• 依托单位: VANDERBILT UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-08-01 至 1995-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3305830
• 关键词: anesthetics; calcium channel; calcium flux; calcium transporting ATPase; calmodulin; conformation; dosage; drug adverse effect; dynein ATPase; halothane; inhalation anesthesia; isoflurane; laboratory rat; lipid bilayer membrane; methylation; methyltransferase; myosins; neural transmission; neutrophil; phospholipids; radiotracer; scintillation counter; synapses; synaptosomes; voltage gated channel

The introduction of inhalational anesthetics a century and a half ago marks a major medical and pharmacologic achievement. Neuronal membranes are favored as a likely site of anesthetic effect, either by biophysical interaction of anesthetics with membrane lipids or by induction of conformational changes in membrane proteins. Clinical anesthesia probably results from interference with information transfer at the synaptic level of brain organization. The overall objective of this proposal is to test the hypothesis that anesthetics interfere with synaptic transmission by altering lipid modulation of the Ca++-ATPase pump. There is good evidence that enzymatic methylation of membrane phospholipids does modulate transduction of biologic signals across cell membranes. Studies from our laboratory show that halothane and isoflurane stimulate phospholipid methylation (PLM) as much as two fold in rat brain synaptosomes. More recent work shows a reduction in Ca++-ATPase pump activity in synaptosomal plasma membrane (SPM) obtained from cerebra, cerebella, midbrains and medullae of rats anesthetized with halothane. This reduction varies from 25% to 75%, with the greatest inhibition seen in the medulla. Pump activity returns to control levels in SPM from rats allowed to recover from anesthesia. The first aim of this proposal is to define characteristics of the calcium pump response to halothane. Dose response of Ca++ pump activity in synaptosomal plasma membranes will be evaluated at halothane concentrations ranging from 0.5 to 2.0%. We recently observed significant PLM stimulation over a wide range of halothane dosage. Possible concomitant halothane effects on SPM gated Ca++ channels and pump activity will also be tested. Linkage of PLM to the calcium pump response to halothane will be examined in experiments in which PLM can be inhibited or stimulated. A large effort will be directed toward testing for calmodulin, lipid, Ca++-ATPase interaction in the anesthetic response. We propose to assess anesthetic effects on Ca++ pump activity in calmodulin depleted and repleted SPM and to study anesthetic effects on purified and reconstituted rat brain Ca++-ATPase. A second aim is to determine where and how inhalational anesthetics affect the PLM pathway. Selective enzyme assays and kinetic studies will be used to identify putative, irreversible changes in methylating enzymes resulting from anesthetic exposure. A third aim is to evaluate the generality of calcium pump and PLM responses to anesthetics.

一个半世纪前引入吸入麻醉药 主要的医学和药理成就。 神经元膜是 通过生物物理可以作为麻醉作用的可能位点 麻醉药与膜脂质的相互作用或通过诱导 膜蛋白的构象变化。 临床麻醉可能 干扰突触级别的信息传输的结果 大脑组织。 该建议的总体目的是测试 麻醉药干扰突触传播的假设 改变Ca ++ ATPase Pump的脂质调制。 有很好的证据 膜磷脂的酶促甲基化可调节 跨细胞膜的生物信号转导。 我们的研究 实验室表明氟烷和异氟烷会刺激磷脂 大鼠脑突触体中甲基化（PLM）多达两倍。 更多的 最近的工作表明，突触体中Ca ++ -ATPase Pump活性的降低 从小脑，小脑，中脑和 大鼠的髓质用硫烷麻醉。 这种减少因 25％至75％，在髓质中看到最大的抑制作用。 泵 活动从大鼠的SPM中返回控制水平，允许从 麻醉。 该提议的第一个目的是定义 钙泵对氟烷的响应。 Ca ++泵的剂量响应 突触体质膜中的活性将在硫烷中评估 浓度范围为0.5至2.0％。 我们最近观察到了重要的 PLM刺激在多种烟烷剂量上。 可能的 对SPM门控Ca ++通道和泵活动的氟烷伴随效果 也将进行测试。 PLM连接到钙泵的响应 将在可以抑制PLM或 刺激。 将大力努力用于测试钙调蛋白， 脂质，Ca ++ - 麻醉反应中的ATPase相互作用。 我们建议 评估对钙调蛋白耗尽的CA ++泵活性的麻醉作用，并且 填充SPM并研究对纯化和重构的麻醉作用 大鼠脑CA ++ ATPase。 第二个目的是确定何处以及如何 吸入麻醉剂会影响PLM途径。 选择性酶测定 动力学研究将用于识别推定的，不可逆的变化 在麻醉暴露引起的甲基化酶中。 第三个目标是 评估钙泵和PLM响应的一般性 麻醉药。