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.

一个半世纪前吸入麻醉剂的引入标志着 一项重大的医学和药理学成就。 神经元膜是 通过生物物理学，被认为是麻醉作用的可能部位 麻醉剂与膜脂的相互作用或通过诱导 膜蛋白的构象变化。 临床麻醉可能 突触水平信息传递受到干扰的结果 的大脑组织。 该提案的总体目标是测试 麻醉药干扰突触传递的假设 改变 Ca++-ATPase 泵的脂质调节。 有充分的证据 膜磷脂的酶促甲基化确实调节 跨细胞膜的生物信号转导。 来自我们的研究 实验室表明氟烷和异氟烷刺激磷脂 大鼠脑突触体中的甲基化 (PLM) 高达两倍。 更多的 最近的研究表明突触体中 Ca++-ATP 酶泵活性降低 质膜（SPM）取自大脑、小脑、中脑和 用氟烷麻醉的大鼠的髓质。 这种减少的变化范围为 25% 至 75%，其中髓质的抑制最大。 泵 恢复正常的大鼠的 SPM 活性恢复到控制水平 麻醉。 该提案的首要目标是定义 钙泵对氟烷的反应。 Ca++ 泵的剂量响应 将在氟烷中评估突触体质膜的活性 浓度范围为0.5%至2.0%。 我们最近观察到显着 在广泛的氟烷剂量范围内进行 PLM 刺激。 可能的 氟烷对 SPM 门控 Ca++ 通道和泵活性的影响 也将受到考验。 PLM 与钙泵响应的联系 氟烷将在可抑制 PLM 的实验中进行检查或 受到刺激。 我们将投入大量精力来测试钙调蛋白， 麻醉反应中脂质、Ca++-ATP酶相互作用。 我们建议 评估钙调蛋白耗尽和麻醉对 Ca++ 泵活性的影响 补充 SPM 并研究纯化和重构的麻醉效果 大鼠脑 Ca++-ATP 酶。 第二个目标是确定在何处以及如何 吸入麻醉药影响 PLM 通路。 选择性酶测定 动力学研究将用于识别假定的、不可逆转的变化 因麻醉剂暴露而产生的甲基化酶。 第三个目标是 评估钙泵和 PLM 响应的一般性 麻醉剂。