BACKGROUND POTASSIUM CHANNELS AS ANESTHETIC TARGETS

尽管人们在150多年前就知道这种挥发性 麻醉药在许多情况下引起中枢神经系统(CNS)抑制 物种，麻醉作用的基本机制还不是很清楚 明白了。我们假设挥发性麻醉剂诱导神经元 主要通过激活一类不连续的钾(K)来抑制 负责背景电流的通道(也称为基线或 泄漏电流)。我们已经证明，在软体动物海兔的神经元中 加州，挥发性麻醉剂增加开放的概率 向外整流背景K通道(S-K通道)，导致 神经元超极化与自发动作的沉默 潜力。最近发现的一类K通道，区别于 通过在内部排列两个假定的成孔序列 它们的主要氨基酸序列似乎是背景的中介 洋流。我们发现这个原型成员的功能 家族，一个酵母外向整流背景通道(TOK1)是 被挥发性麻醉剂强化了。TOK1增强服从等级 临床效价等级氟烷大于异氟醚大于 地氟醚)，与临床范围重叠，不会发生在非 麻醉药物，立体特异性[S()大于R(-)-异氟烷]。 我们也有初步证据证明挥发性物质的存在 麻醉刺激哺乳动物(大鼠)脑内基线K通道 小脑颗粒细胞)。我们现在建议继续实施这些措施 串联孔K新成员的克隆与表达研究 通道家族，用于研究他们对挥发性麻醉药的敏感性。 拟议的研究从三个角度来看是重要的：1)它们具有 阐明挥发性疾病分子机制的可能性 麻醉作用；2)它们将使人们更好地理解 背景通道在中枢神经系统活动中的作用；3)它们可能提供靶点 用于开发更具体的麻醉剂。

Although it has been known for more than 150 years that volatile anesthetics produce central nervous system (CNS) depression in numerous species, the basic mechanisms underlying anesthetic action are not yet understood. We hypothesize that volatile anesthetics induce neuronal inhibition primarily by activating a discrete class of potassium (K+) channels responsible for background currents (also known as baseline or leak currents). We have shown that in neurons of the mollusc Aplysia californica, volatile anesthetics increase the open probability of an outwardly rectifying background K+ channel (S-K channel), resulting in neuronal hyperpolarization and silencing of spontaneous action potentials. A recently discovered class of K+ channels, distinguished by having two putative pore-forming sequences tandemly arrayed within their primary amino acid sequence, appears to mediate background currents. We found that the function of the prototypic member of this family, a yeast outwardly rectifying background channel (TOK1) is potentiated by volatile anesthetics. TOK1 potentiation obeys the rank order of clinical potency halothane greater than isoflurane greater than desflurane), overlaps the clinical range, does not occur with non- anesthetics and is stereospecific [S(+) greater than R(-)-isoflurane]. We also have preliminary evidence for the presence of volatile anesthetic-stimulated baseline K+ channels in mammalian brain (rat cerebellar granule cells). We now propose the continuation of these studies by cloning and expressing new members of the tandem pore K+ channel family for studies of their sensitivity to volatile anesthetics. The proposed studies are important from three perspectives: 1) they have the potential for elucidating a molecular mechanism of volatile anesthetic action; 2) they will lead to a greater understanding of the role of background channels in CNS activity; 3) they may provide targets for the development of more specific anesthetic agents.